DE102021001635A1 - Trapping and destroying viruses and other microorganisms on surfaces, in room air, in the exhaust air from vacuum cleaners and in room air filters. - Google Patents

Abstract

A system is presented with which viruses and other microorganisms are captured from the air and irreversibly deactivated by a hygroscopic salt solution with high osmotic pressure and/or with a chaotropic, i.e. "structure-breaking" effect, and the viruses and other microorganisms are crushed by crystallization, i.e. efflorescence against which there is no development of resistance.The viruses are trapped by a permanently moist, hygroscopic liquid film on filters or mouth-nose protective masks or via nebulised liquid droplets.The trapped microorganisms are denatured by the denaturing effect of concentrated salt solutions and during the crystallization of selected salts mechanically crushed.

Description

A: The purpose of this patent is to capture and destroy viruses using saline solutions

See Fig. 1 Virus spread and mask interception

A system is presented with which viruses and other microorganisms are captured from the air and irreversibly deactivated by a salt solution with high osmotic pressure and/or with a chaotropic, i.e. "structure-breaking" effect, and the viruses and other microorganisms are crushed by crystallization, i.e. efflorescence , against which there can be no development of resistance.

This means a great advantage over existing simple masks in which microorganisms are only intercepted but not deactivated and many microorganisms can multiply in the warm, humid climate of the breathing mask and thus pose a health risk to the mask wearer if he does not dry out the mask again and again leaves or washes.

See Fig. 2 Virus attack on human cell and virus destruction

B: Prior art of killing viruses by saline solutions

B.1: Existing patents for virus destruction on surfaces

• Neben harter UV-Strahlung und noch höher energetischer Strahlung kommen Schwermetallsalze wie Silber- und Kupfersalze zur Anwendung.

Some of the previously known methods and substances for deactivating viruses are extremely harmful to health:

• In addition to hard UV radiation and even higher energy radiation, heavy metal salts such as silver and copper salts are used.

• Beispielsweise die Behandlung mit ß-Propiolacton, Formaldehyd oder Ethylenimin. Die Handhabung derartiger Reagenzien ist jedoch potentiell gefährlich, und eine sichere Methode wäre wünschenswert.

Previous methods of protecting against and disabling viruses can be found in the following patents:

• For example, treatment with ß-propiolactone, formaldehyde or ethyleneimine. However, handling such reagents is potentially hazardous and a safe method would be desirable.

The patent DE 10 2016 002 826 A1 14.09.2017 relates to a respiratory protection mask for protection against droplet infections, having a filter surface covering at least the mouth area of a person, disinfection of pathogens in the contact area of the filter surface to the ambient air taking place by electrolysis of a sodium chloride solution (NaCl) and having an electrolysis cell.

With heavy metal salts, viruses become patent WO97/25415 disabled.

There, a method for deactivating HIV and other viruses is described, which have a high chemical affinity for polyvalent heavy metals. The virus proteins are cationized there and made virucidal. The chemically bound heavy metal is converted into a poorly soluble compound through a chemical reaction, preferably into a "chelate complex"

By phenyl ketone are in the patent DE 28 42 091 A1 1979 enveloped viruses disabled.

Certain betaines are patent DE 10 2016 002 826 A1 2017.09.14 Viruses disabled.

According to EP 000000357693 B1 viruses are separated by zeolites.

Using diisopropylfluorophosphatase for decontamination and waterproofing of clothing Patent DE 198 08 192 A1 .

In the patent DE000019808192A1 Viruses are destroyed by an enzyme.

In DE 38 86332 T2 viruses are deactivated with ascorbic acid and/or a salt thereof in the presence of oxygen and heavy metal ions.

In EP 000000357693 B1 Viruses are separated by large-pored molecular sieves.

In DE 3528209 C2 relates to aldehyde-free disinfectants, in particular agents for disinfecting areas, surfaces, instruments and/or laundry, consisting of biguanides and/or guanidine derivatives and optionally quaternary ammonium compounds and/or nonionic and/or cationic surfactants and other customary auxiliaries.

In DE 198 08192 A1 uses diisopropylfluorophosphatase for, in particular, the decontamination of contaminated habitats, the manufacture of drugs for the treatment or detoxification of humans and animals, the impregnation of clothing and use in analytics

The principle of mechanical virus destruction through crystallization or through high salt concentrations has already been used several times. Ammonium salts were used for this because of their extremely good water solubility. Viruses are treated with alkaline ammonium salts EP 1 053 754 A1 disabled.

DE 199 23 027 C2 from 2002 describes the use of an ammonium salt for the inactivation and/or elimination of enveloped and/or non-enveloped viruses from a plasma protein solution with a fractionated ammonium salt precipitation in alkaline solution.

1 Trapping the viruses with liquids, salt and surfactant solutions

According to the latest findings, the COVID-19 virus is mainly transmitted through the air. Naked viruses, i.e. viruses without a water droplet shell, can remain freely floating in the air for days.

In order to render these viruses harmless in the inhaled air, the viruses must be filtered out of the air. Viruses cannot fly straight through dry tissue, e.g. from a simple mouth and nose protection mask. Nevertheless, after several wall contacts, some viruses can get through the tissue cave system, which is large for the virus, and ultimately infect humans.

• In diese Tröpfchen oder diese Flüssigkeitsfilme tauchen die Viren unelastisch ein und bleiben darin fixiert. Verdunsten die Tröpfchen, bevor sie den Fußboden erreicht haben, werden die Viren allerdings wieder frei. Ebenso können Viren aus dem Wasserfilm der Maske - wenn dieser eintrocknet - wieder frei werden. Deshalb ist es wichtig - neben dem Einfangen und dem Herausfiltern der Viren aus der Luft - noch einen zweiten die Viren zerstörenden Mechanismus einzuführen. Siehe dazu Kapitel 2!

On the other hand, the viruses are caught on and in damp filter masks as soon as they come into contact with the wall. Viruses can also be caught and rained out by spraying liquid droplets from the air:

• The viruses immerse themselves in these droplets or these liquid films in an inelastic manner and remain fixed therein. However, if the droplets evaporate before they reach the floor, the viruses are released again. Likewise, viruses can be released again from the water film of the mask - if it dries up. It is therefore important - in addition to capturing and filtering out the viruses from the air - to introduce a second virus-destroying mechanism. See Chapter 2!

1.1 Aqueous solutions

Aqueous solutions catch viruses, but small water droplets or thin water films evaporate quickly, which limits the time for which the viruses can be fixed. However, in the case of breathing masks, for example, there is constant humidification by the breathing air. Cotton masks in particular absorb water and carry a constant film of liquid. Therefore, these cotton masks are safer than the dirt masks made of non-polar materials such as polypropylene (PP) and polyethylene (PE), which hardly carry a film of liquid. This means that wet masks are also good virus collectors. These in turn pose a danger to the wearer of the protective mask. It is therefore recommended that wet masks should only be touched by the rubber bands and that they should be changed as often as possible. ¹ These changes are not necessary if the viruses in the mask are constantly deactivated or destroyed. See Chapter 2.

1.2 High-boiling hygroscopic liquids

As long as the filter is damp or the liquid droplets in the air have not evaporated, the viruses remain fixed in it. It is therefore advantageous - in addition to the rapidly evaporating water - to use high-boiling, hygroscopic water-miscible liquids such as glycerol and/or 1,2-propanediol and/or triethylene glycol and/or PEG 200 and/or PEG 400 and/or Tween 20 or mixtures thereof. These permanently moist filters or masks have a far better filtering and retention effect for viruses than dry filters.

2 Viruses and other microorganisms denaturing action of concentrated salt solutions and viruses and other microorganisms destroying forces in the crystallization of salts:

According to Fu-Shi Quan et. al. ² - as follows in two stages: First, the water droplets with the viruses from the breathing air dissolve the salt crystals. The high salt concentration removes the water from the viruses and deforms their proteins, which means that the viruses can no longer dock to human cells. When the water evaporates, salt crystals form, which crush the viruses. ³ , ⁴ , ⁵

These powerful forces are also behind the weathering of rock, which causes structural damage ⁶ , ⁷ , ⁸ . The alternating dissolution of salt in the condensed water from the air and the crystallization of this salt in the rock pores when it is dry is what drives this destruction ⁹ : during crystallization, when entire companies of ions are attracted by the oppositely charged ions, forces arise for which the hardest Material cannot withstand in the long run. “The crystallization of salts in hairline cracks in the rock creates a crystallization pressure (1000 to 4000 kg/cm ² ≈ 100 N/mm ² ) which, like frost cracking, destroys the rock structure ¹⁰ , ¹¹ ; ¹² , ¹³ . Hydrated crystals of, for example, CaSO ₄ , Na ₂ SO ₄ , MgSO ₄ , Na ₂ CO ₃ have a volume that is up to 300% larger than their unhydrated salts ¹⁴ : The molar volume of crystalline MgSO ₄ * 7 H ₂ O = 149 cm ³ /mol over 3 times larger than that of crystalline MgSO ₄ = 44 cm ³ /mol.

When a virus crystallizes out of a salt, it experiences a pressure of 1000 atmospheres and, if it were enlarged to 1 mm, it would be crushed with a weight of 1-4 kg.

The aim of this work is to use these forces for the mechanical destruction of viruses.

See Fig. 2 Virus attack on human cell and virus destruction

Fu-Shi Quan, Ilaria Rubino, Su-Hwa Lee, Brendan Koch & Hyo-Jick Choi proved in 2017 ¹⁵ that salt actually also destroys viruses mechanically. They impregnated the inner filter layer of protective masks with a saturated saline solution and added a surfactant to the saline solution to improve adhesion to the non-polar polypropylene fabric. Using animal experiments and electron microscopic investigations, they showed that the viruses in water droplets lost their activity within 5 minutes when they came into contact with the sodium chloride crystals that formed.

The aim of this work is to provide various methods and salt mixtures with which viruses can be intercepted and destroyed mechanically in a wide temperature and humidity range.

Salt mixtures that mimic cyclical destruction of matter, such as mineral weathering, are beneficial.

See Fig. 3 Interaction between water and salt and its effect on viruses and rock

This mechanical destruction of viruses also takes place, for example, on human skin due to the salt that is sweated out.

2.1 Hygroscopic Salts

Cyclic destruction can be achieved with hygroscopic salts that gradually incorporate water of crystallization into their crystal. This crystal expands significantly and mechanically destroys viruses, for example. The forces occurring during the conversion into higher hydrates of Ca(NO ₃ ) ₂ and Na ₂ SO ₄ ¹⁶ , ¹⁷ were measured.

2.2 Deliquescent salts

Deliquescent salts, which liquefy when the relative humidity increases and crystallize again when the relative humidity decreases, have a mechanical effect on viruses.

Much of the study of the deliquescence (liquefaction of salts in their own crystal water at elevated humidity) and efflorescence (crystallization of salts from a saturated solution) of salts has been undertaken by researchers in the fields of atmospheric chemistry and climate carried out because salt crystals are important as nuclei for water condensation and thus rain formation even at low humidity ¹⁸ , ¹⁹ , ²⁰ In addition, deliquescent salts are used in the food industry as moisture retainers and for thermochemical heat storage ²¹ , for the effect of filters ²² and for prolonging the scent impression of perfumes ²³ interesting.

1. 1. Von der relativen Luftfeuchtigkeit.
2. 2. Von der Teilchengröße (Kristallgröße).
3. 3. Von der Anwesenheit von Fremdsalzen, die die Kristallisation beschleunigen oder behindern und bestimmte Kristallformen bedingen.
4. 4. Von der Wirkung von Fremdsalzen auf die Salzlösung, in dem die Fremdsalze den Dampfdruck gemäß dem Raoultschen Gesetz senken. So blühen Salze unter dem Einfluss von Fremdsalzen schon bei einer geringeren relativen Luftfeuchtigkeit aus.
5. 5. Die Deliqueszenzfeuchte (DRH) und Effloreszenzfeuchte (ERH) von Salzmischungen gehorcht näherungsweise dem Gesetz von Duhmen, das heißt: Die DHR und EHR eines Elektrolyten werden durch die Zugabe eines weiteren Elektrolyten gesenkt. Die Kristallisationsfeuchte (ERH) einer Salzmischung errechnet sich aus dem Produkt der Kristallisationsfeuchten (ERH_i) der in Kontakt stehenden Komponenten (i):
   • ERH_0,mix /100 = ERH_0,1/100 * ERH_0,2/100 .....*ERH_0,i/100
6. 6. Die Deliqueszenz (Verflüssigung) und Effloreszenz (Auskristallisieren) finden zumeist bei unterschiedlichen Luftfeuchtigkeiten statt. Es gilt aber grundsätzlich DRH > ERH.
   1. a. Oft ist die Verflüssigung der Kristalle gehemmt und findet erst bei genügend kondensierter Feuchtigkeit und damit erhöhter relativer Luftfeuchtigkeit statt.
   2. b. Die Deliqueszenz - das Auskristallisieren - findet oft erst ab einer gewissen Übersättigung der Salzlösung, das heißt bei einer niedrigeren relativen Luftfeuchtigkeit statt.
   3. c. Bestimmte Zusätze wie Glycerin lassen Verflüssigung und Auskristallisieren parallel stattfinden.
7. 7. Die Deliqueszenzfeuchte und Effloreszenzfeuchte hängen von dem Anteil an organischer Flüssigkeit ab.

The efflorescence moisture (ERH = efflorescence moisture with decreasing relative humidity (RH)) depends on many parameters:

1. 1. From the relative humidity.
2. 2. From the particle size (crystal size).
3. 3. From the presence of foreign salts that accelerate or hinder crystallization and cause certain crystal forms.
4. 4. From the effect of extraneous salts on the salt solution, in which the extraneous salts lower the vapor pressure according to Raoult's law. Salts bloom under the influence of foreign salts even at a lower relative humidity.
5. 5. The deliquescence moisture content (DRH) and efflorescence moisture content (ERH) of salt mixtures approximately obeys Duhmen's law, ie: The DHR and EHR of an electrolyte are lowered by the addition of another electrolyte. The moisture content of crystallization (ERH) of a salt mixture is calculated from the product of the moisture content of crystallization (ERH _i ) of the components (i) in contact:
   • ERH _0,mix /100 = ERH _0,1 /100 * ERH _0,2 /100 .....*ERH _0,i /100
6. 6. The deliquescence (liquefaction) and efflorescence (crystallization) usually take place at different humidity levels. In principle, however, DRH > ERH applies.
   1. a. The liquefaction of the crystals is often inhibited and only takes place when there is sufficient condensed moisture and thus increased relative humidity.
   2. b. The deliquescence - the crystallization - often only occurs when the salt solution is oversaturated to a certain extent, i.e. at a lower relative humidity.
   3. c. Certain additives such as glycerin allow liquefaction and crystallization to take place in parallel.
7. 7. The deliquescence moisture and efflorescence moisture depend on the proportion of organic liquid.

3 Denaturation of viruses and other microorganisms through dehydration at high osmotic pressure of the salts:

Salts remove water from the virus, which reduces its activity: (osmotic dehydration). The osmotic pressure is calculated from the solubility of the salt and the number of ions formed per mole. Correctly, the ion activity should be used instead of the ion concentration determined from this.

4 Protein denaturation by ions:

4.1 Ions with a high ionic charge:

Due to their ionic charge, salts have a deforming effect on the proteins. The effect is much greater with multivalent ions. However, a thicker water shell - which is present with these multiply charged ions - can weaken this strong effect. →protein denaturation.

4.2 Dehydration by ions:

The deactivation of the viruses by the osmotic pressure at high salt concentrations, whereby the proteins of the viruses are refolded ²⁴ , ²⁵ and lose their function, for example when docking to the human cell, and thus their virulence. Concentrated salt solutions have a dehydrating effect on the proteins. This also changes their structure. →protein denaturation

4.3 Disruption of Hydrogen Bonds

Salts that form hydrogen bonds themselves can thus destroy the hydrogen bonds in the proteins. →protein denaturation. These include urea, ammonium salts, formates, sorbates, ascorbates, propionates, lactates, carbonates, as well as acidic and basic salts

4.4 Reducing Salts

Reducing salts, because they break the sulfur-sulfur bond in proteins, have the ability to denature them: sodium thiosulfate, thioglycolates.

4.5 Heavy metal salts

Heavy metal ions bind to and block thionyl groups. When reducing salts interact with heavy metal salts, the -S-S- group, reduced to two thionyl groups, will irreversibly bind the heavy metals, which tends to denature this protein.

4.6 Chaperones

Certain salts deform the proteins as chaperones. These include sodium salicylate, urea and the solvent propylene glycol

4.7 Process of deactivation and destruction of viruses during crystallization

See Fig. 2 Virus attack on human cell and virus destruction

• 1.1.1. Die Ionen aus Salzlösungen lagern sich an Proteine und denaturieren diese. Gleichzeitig benutzen die Ionen der Salzlösung das Protein als Keim für die Salzkristallbildung.
• 1.1.2. Das Kristallwachstum geht somit von Virusprotein aus und umschließt schließlich den gesamten Virus.
• 1.1.3. Bei der Kristallisation treten durch starken elektrostatischen Kräfte zwischen den entgegen gesetzt geladenen vielen Ionen auf, die den Virus schließlich zerquetschen.
• 1.1.4. Auch von Salzkristallen, die hygroskopischen Wasser aufnehmen und sich dabei erhebliche ausdehnen, können Viren einklemmen und zerstören werden. Dieses Umkristallisieren unter Wasseraufnahme kann bei manchen Salzkristallen über mehrere Hydratformen in Abhängigkeit von der jeweiligen relativen Luftfeuchtigkeiten geschehen. Beispiele für solche Salze sind Calciumchlorid und Magnesiumsulfat.

In this patent, salts and salt mixtures are presented which deactivate viruses due to the high osmotic pressure of their saturated solution. In addition, salts with a low equilibrium moisture content (deliquescence) are important for use in dry room air.

• 1.1.1. The ions from salt solutions attach themselves to proteins and denature them. At the same time, the ions in the salt solution use the protein as a nucleus for salt crystal formation.
• 1.1.2. Crystal growth thus starts from viral protein and eventually encloses the entire virus.
• 1.1.3. During crystallization, strong electrostatic forces occur between the oppositely charged many ions, which eventually crush the virus.
• 1.1.4. Viruses can also be trapped and destroyed by salt crystals, which absorb hygroscopic water and expand considerably in the process. In the case of some salt crystals, this recrystallization with the absorption of water can take place via several hydrate forms, depending on the respective relative humidity. Examples of such salts are calcium chloride and magnesium sulfate.

5 surfactants

In this interplay of substances that intercept and deactivate viruses, surfactants with their emulsifying effect, which fixes viruses and salt crystals and destroys the virus envelope, must not be missing.

5.1 Surfactant and solid surface:

5.1.1 Surfactants as an adhesive

Surfactants act as glue for the saline solution, salt crystals and viruses on non-polar surfaces.

Surfactants establish contact with non-polar surfaces

Surfactants facilitate the impregnation of surfaces of fabric by lowering the surface tension, which is much greater for a concentrated salt solution than for pure water.

5.1.2 Effect of surfactants on viruses

5.1.2.1 Surfactants attack the lipid membranes of the virus

Surfactants sit between the lipids and thus weaken the lipid membrane. This can eventually cause the virus to burst open and be destroyed.

5.1.2.2 Surfactant micelles transport salts through the virus envelope

A saline solution can be transported into the virus via surfactant micelles, thereby denaturing the virus

5.1.2.3 Quaternary Surfactants ²⁶

Surfactants (especially those with quaternary ammonium groups) denature proteins. In this respect, fabric softeners, amphoteric amines such as lecithin, betaine are particularly effective in deactivating viruses. Therefore, these surfactants are not harmful to our skin.

5.1.2.4 Neutral surfactants, amphoteric surfactants and surfactant mixtures

One function of the surfactants in the impregnation solution is to promote adhesion between the salt and a water-repellent, non-polar surface. Both non-hygroscopic and hygroscopic surfactants with a hydrophilic-lipophilic balance value (HLB value) between 8 and 18 are suitable for this. Neutral surfactants or amphoteric surfactants are suitable.

Hygroscopic surfactants are advantageous because they promote the liquefaction of salts. These include the non-ionic surfactants ^{27, 28, 29} such as the alkyl glycosides Tween 20 (E 432), Tween 40 (E 434) Tween 60 and various monoglycerides (E 471 - E 472).

Ionic surfactants are disruptive because they are precipitated by salts.

Tween 60, 65 are less emulsifiable in water and therefore not ideal, and depending on the type of fabric to be impregnated, other surfactants such as the slightly hygroscopic lecithin in an alcoholic solution or a mixture of different neutral surfactants can also be used. These surfactants must emulsify well in water, must not be precipitated at high salt concentrations and must be approved for medical purposes and the food industry.

Suitable examples are: polyalkylene glycol ether, polyoxyethylene sorbitan monolaurate), alkyl polyglycoside, polysaccharides (less suitable as they are too polar) and lecithin.

Some polysaccharides are less suitable because they have a slightly corrosive effect. Surfactants that cause allergies and are otherwise harmful to health, such as tallowamine, polysorbate 80 ³⁰ and octylphenol ethoxylate and nonylphenol ethoxylate, are not suitable due to their strong hormone effects.

Mixtures of several surfactants are not advantageous unless the cheaper surfactant is mixed with an expensive, e.g. hygroscopic, surfactant.

6 selection criteria for the substances in the impregnation

Basically, the impregnation solution must be safe!

1. 1. gefahrlos,
2. 2. nicht umweltgefährdend,
3. 3. ohne Probleme zu entsorgen und ohne Schadwirkungen (im Gegensatz zu im Patent WO97/25415 verwendeten Schwermetallsalzen),
4. 4. leicht auswaschbar,
5. 5. langzeitwirksam, da die Salze bei der Desaktivierung und Zerstörung der Viren nicht verändert werden,
6. 6. leicht verfügbar,
7. 7. zumeist nicht brennbar (Dies gilt vor allem für die anorganischen Salze.),
8. 8. zumeist wirken feuerhemmend durch Verringerung der Oberfläche des Gewebes,
9. 9. leicht erneuerbar,
10. 10. mit geringen Kosten verbunden.
11. 11. Die Salz-Tensid-Lösungsmittel-Mischung behält ihre Wirksamkeit, solange sie nicht ausgewaschen wird.
12. 12. Die Substanzen können nicht zur Bildung multiresistenter Mikroorganismen führen, da diese in der konzentrierten Salzlösung in den inaktiven Zustand übergehen.
13. 13. Sie verursachen keine Reizung oder Schädigung der Augen, Haut und Atemwege.
14. 14. Sie sind als Lebensmittelzusatzstoffe und zum Teil als Bestandteilen von Arzneimitteln zugelassen.
15. 15. Sie bilden möglichst keinen Nährboden für Mikroorganismen.
16. 16. Sie verursachen keine Umweltschäden, z.B. für Wasserorganismen.
17. 17. Sie sind biologisch abbaubar, außer den Salzen.
18. 18. Sie sind abwaschbar.
19. 19. Sie verursachen keine Veränderung von Farbe.

The substances to be used for the impregnation are - in contrast to other antivirally active substances such as heavy metal salts - according to the prior art

1. 1. safe,
2. 2. non-hazardous to the environment,
3. 3. Dispose of without problems and without harmful effects (unlike in the patent WO97/25415 used heavy metal salts),
4. 4. easily washable,
5. 5. long-term effective, since the salts are not changed during the deactivation and destruction of the viruses,
6. 6. readily available,
7. 7. mostly non-combustible (this applies above all to the inorganic salts.),
8. 8. mostly have a fire retardant effect by reducing the surface area of the fabric,
9. 9. easily renewable,
10. 10. low cost.
11. 11. The salt-surfactant-solvent mixture will remain effective as long as it is not washed out.
12. 12. The substances cannot lead to the formation of multi-resistant microorganisms, since they become inactive in the concentrated salt solution.
13. 13. They do not cause irritation or damage to the eyes, skin and respiratory tract.
14. 14. They are approved as food additives and in some cases as components of medicinal products.
15. 15. If possible, they form no breeding ground for microorganisms.
16. 16. They do not cause any harm to the environment, eg to aquatic organisms.
17. 17. They are biodegradable, except for the salts.
18. 18. They are washable.
19. 19. They cause no change in color.

6.1 Impregnation solution

6.1.1 Liquids to catch the viruses from the air

The most important component of the impregnation solution is a readily soluble salt and the associated solvent, as well as a surfactant for non-polar, i.e. water-repellent surfaces. This surfactant is usually superfluous on polar surfaces.

"Naked" viruses, i.e. viruses that become free after the evaporation of the water droplets in the breathing air, move quickly in the air - thanks to the collisions caused by the air molecules (Brownian motion). Depending on the size of the virus, they have an average speed of 7 cm/s with a virus diameter of 0.160 µm to 30 cm/s with a virus diameter of 0.06 µm.

The spread of the naked viruses is therefore also given when there is no wind.

These naked viruses are easily washed out of the air by liquid droplets.

The liquid acts as an inelastic shock absorber for free-flying viruses. Once immersed, the virus remains stuck in the liquid because strong, flexible forces develop immediately from the liquid to the virus: The solvent molecules can easily orient themselves towards the virus, which is not possible with the molecules of a solid substance (e.g. the protective mask or dry filter). is.

High-boiling liquids that are compatible with water, as well as hygroscopic liquids and surfactants and deliquescent salts guarantee a permanent liquid film for catching the viruses.

1. 1. Wassertröpfchen verdunsten je nach ihrer Größe innerhalb von Bruchteilen einer Sekunde und ab 0,1 mm Tröpfchendurchmesser innerhalb von mehreren Sekunden. Innerhalb dieser Zeiten müssen die Viren „aus dem Verkehr“ gezogen werden. Deshalb wird für das „Ausregnen“ von Viren Wassertröpfchen ab einen Durchmesser größer 0,5 mm vorgeschlagen, die rasch genug zum Boden sinken, wo der Virus verbleibt. Nachteilig ist, dass der Boden dabei feucht wird.
2. 2. Besser ist, wenn dem Wasser eine hochsiedende Flüssigkeit beigefügt wird. Dann verbleiben auch kleinere Tröpfchen über Minuten in der Luft und können sich in dieser Zeit zusammen mit den eingefangenen Viren auf dem Boden absetzen. Dort fixiert das hochsiedende Lösungsmittel die Viren. Gut sichtbar ist dies bei den E-Zigaretten, wo zuerst einen weißer kompakter Nebel entsteht, der viel Wasser - auch aus der Luft - enthält. Dieser kompakte Nebel verschwindet rasch, wobei ein feiner transparenter Nebel aus den hochsiedenden Flüssigkeitströpfchen längere Zeit in der Luft verbleibt und sich absetzt.
3. 3. Als Nebelfluide³ für E-Zigaretten und Nebelmaschinen finden folgende Flüssigkeiten neben Wasser ihre Anwendung und Zulassung:

This capture is favored by the polar surface of the virus and the polar liquid used.

1. 1. Depending on their size, water droplets evaporate within fractions of a second and within several seconds from a droplet diameter of 0.1 mm. The viruses must be "taken out of circulation" within these times. For this reason, water droplets with a diameter greater than 0.5 mm are suggested for “raining out” viruses, which sink quickly enough to the ground where the virus remains. The disadvantage is that the soil gets wet.
2. 2. It is better if a high-boiling liquid is added to the water. Then even smaller droplets remain in the air for minutes and can settle on the ground together with the captured viruses during this time. There, the high-boiling solvent fixes the viruses. This is clearly visible in the case of e-cigarettes, where a white, compact mist is first produced that contains a lot of water - also from the air. This compact mist disappears quickly, leaving a fine transparent mist of the high-boiling liquid droplets in the air for a long time and settling.
3. 3. In addition to water, the following liquids are used and approved as smoke fluids ³ for e-cigarettes and smoke machines:

glycerin

The advantage of adding up to 50% glycerine is that you get long-lasting fog, which settles after some time and in the meantime safely catches most of the viruses and other microorganisms from the air.

With continued use of the glycerin, the surfaces become sticky and these surfaces continue to trap viruses. This covering is easily washable with water.

Propanediol 1,2

1,2-Propanediol with a boiling point of 188 °C is not as high-boiling as glycerol (290 °C). It has the advantage that it deactivates the proteins of the viruses through its chaotropic effect.

PEG, macrogol

Depending on the composition, polyethylene glycol PEG 400 boils at over 200 °C and can be used with glycerin or alone. Triethylene glycol with a boiling point of 280 °C is best. This boiling point can be greatly reduced by adding water. Glycol and diethylene glycol should be rejected for health reasons.

tween 20

Tween 20 can be used as an evaporable surfactant (boiling temperature above 100 °C.). As a surfactant, it envelops the virus and damages its membrane. A disadvantage of Tween 20 is its inherent odor, which is why its concentration in the impregnation solution should remain below 1%.

fog fluids

The following are used as fog fluids: glycerin (E 422), 1,2-propanediol = 1,2-propylene glycol (E 1520), dipropylene glycol, 1,2-butylene glycol, 1,3-butylene glycol and mixtures of polyethylene glycol.

The polyethylene glycols are usually present as a mixture of ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol etc. and are referred to as PEG 200, 400, 600... depending on the average molar mass

6.1.2 Salt

6.1.2.1 The salt must be easily soluble

The salt must be easily soluble in water or in the solvent used so that a sufficiently high osmotic pressure is achieved.

• Dazu gehören die Chloride und Sulfate von Ammonium, Natrium, Kalium, und Magnesium, sowie die Acetate von Ammonium, Natrium, Kalium, Calcium und Magnesium und die Formiate von Natrium, Kalium, und Magnesium, Citrate und Hydrogenphosphat und Harnstoff.

Tabelle 1 Salz geordnet nach fallendem osmotischem Druck. Geeignet nur für Luftfilter! Salz geordnet nach fallendem osmotischem Druck. Geeignet nur für Luftfilter Löslichkeit g/L bei 20°C Formel osmotischer Druck in Bar no bedeutet keine Gefahrensymbole Zinkchlorid 4300 g/L ZnCl₂ 2306 Bar H 302 - 314 - 410 Kaliumformiat 2500 g/L CHKO₂ 1450 Bar no Natriumhydrogensulfat 2435 g/L Na⁺ HSO₄ ^2- 1289 Bar H 318 Kaliumacetat E261 2560 g/L C₂H₃KO₂ 1273 Bar no Cäsiumfluorid 3670 g/L CsF 1176 Bar H301 -311 - 314 - 33 1 Ammoniumnitrat 2089 g/L NH₄NO₃ 1144 Bar explosiv! Ammoniumfluorid 820 g/L NH₄F 1080 Bar H 301+311+331 Ammoniumthiocyanat 1600 g/L NH₄SCN 1026 Bar H 302+312+332 - 318 - 412 Lithiumchlorid 832 g/L LiCl 956 Bar H 302 - 315 - 31 Ammoniumacetat 1480 g/L C₂H₇NO₂ 935 Bar no Kaliumhydrogenphosphat 1600 g/L K₂HPO₄ 896 Bar no Magnesiumchlorid E 511 2350 g/L MgCl₂*6 H₂O 846 Bar no Calciumnitrat E 341 2710 g/L Ca(NO₃)₂*4 H₂O 839 Bar H 272-302-318 Ammoniumsulfamat 1950 g/L NH₄(SO₃NH₂) 833 Bar H 302 Lithiumbromid 1450 g/L LiBr 812 Bar H 302 -315 - 319 - 317 Kaliumpropionat 1780 g/L C₃H₅KO₂ 773 Bar no Natriumdihydrogenphosphat 850 g/L NaH₂PO₄ 690 Bar no Weinsäure 1394 g/L C₄H₆O₆ 679 Bar H 318 Auge Natriumlactat 1500 g/L C₃H₅KaO₃ 652 Bar no Magnesiumacetat 1200 g/L Mg(CH₃COO)₂ 618 Bar no Ammoniumiodid 1770 g/L NH₄I 595 Bar H 315-319 Kaliumcarbonat 1120 g/L K₂CO₃ 593 Bar H 315-319-335 Eisen(III)chlorid 920 g/L FeCl₃ 553 Bar H 290 - 302 - 315 - 318 Cäsiumchlorid 1860 g/L CsCl 539 Bar H 361 Ammoniumhydrogenphosphat 700 g/L (NH₄)₂HPO₃ 517 Bar no Natriumnitrat 874 g/L NaNO₃ 507 Bar H 272-319 Natriumpropionat 995 g/L C₃H₅NaO₂ 504 Bar H 319 Augen Calciumchlorid 740 g/L CaCl₂ 492 Bar H 319 Auge Ammoniumformiat (Futterzusatz) 631 g/L CH₅NO₂ 488 Bar H 315 - 319 - 335 Kaliumsorbat 1400 g/L C₆H₇KO₂ 455 Bar H 315-319 Hautreizungen. Harnstoff E 927b 1100 g/L CH₄N₂O 447 Bar no Manganchlorid 723 g/L MnCl₂ 423 Bar H 302 - 318 - 373 - 411 Kupfernitrat 1378 g/L Cu(NO₃)₂*4 H₂O 418 Bar H 272-302-319 Eisennitrat 1500 g/L Fe(NO₃)₃*6 H₂O 418 Bar H272, H302, H319 Maqnesiumchlorid 542 g/L MgCl₂ 417 Bar no Natriumhypophosphinat 744 g/L NaH₂PO₂ 417 Bar no Ammoniumsulfat 745 g/L NH₄*₂ SO₄ ^2- 412 Bar no Triammoniumcitrat E380 1000 g/L C₆H₁₇N₃O₇ 401 Bar no Ammoniumphosphat 580 g/L (NH₄)₃PO₄ 379 Bar H 315 -319 -335 Ammoniumbromid 742 g/L NH₄Br 369 Bar H 319 Maqnesiumnitrat 712 g/L Mg(NO₃)₂ 352 Bar H 272 Natriumformiat (Futterzusatz) 490 g/L CHNaO₂ 351 Bar no Kaliummalat 1000 g/L C₄H₄K₂O₅ 348 Bar no Ammoniumchlorid 372 g/L NH₄Cl 339 Bar H 302-319 Kupfer(II)chlorid 620 g/L CuCl₂ 338 Bar H 302+312 - 315 - 318 - 410 Aluminiumchlorid 450 g/L AlCl₃ 329 Bar H 314 Natriumchlorid 358 g/L Na⁺ Cl^- 298 Bar no Ammoniumcarbonat 320 g/L (NH₄)₂CO₃ 244 Bar H 302 Kaliumphosphat E 340 508 g/L K₃PO₄ 233 Bar H 318-335 Kaliumchlorid 347 g/L K⁺ Cl^- 227 Bar no Natriumacetat* 3 H2O 613 g/L C₂H₃NaO₂*3H₂O 220 Bar no Kaliumnatriumtartrat E 337 630 g/L C4H₄KNaO₆ 219 Bar no Natriumacetat E 262a 365 g/L C₂H₃NaO₂ 217 Bar no Natriumcarbonat 330 g/L Na₂CO₃·H₂O 194 Bar H 319 Calciumacetat 400 g/L Ca²⁺ OAc^- ₂ 185 Bar no Calciumacetat Dihydrat 440 g/L Ca²⁺ OAc'₂ * 2 H₂O 166 Bar no Zinksulfat-Heptahydrat 965 g/L ZnCl₂*H₂O 164 Bar H 302 - 318 - 410 Kaliumdihydrogenphosphat 222 g/L KH₂PO₄ 159 Bar no Natriumascorbat 620 g/L C₆H₇NaO₆ 153 Bar no Kaliumnitrat 316 g/L KNO₃ 152 Bar H 272-319 Kaliumlactat 400 g/L C₃H₅KO₃ 152 Bar no Ammoniumhydroqencarbonat 220 g/L NH₄HCO₃ 136 Bar H 302 (Verschlucken) Aluminiumsulfat 360 g/L Al₂(SO₄)₃ 128 Bar H 318 Auge Dinatriumtartrat 330 g/L C₄H₄Na₂O₆ 124 Bar no Magnesiumsulfat 300 g/L Mg²⁺ SO₄ ^2- 122 Bar no Kaliumtartrat 300 g/L C₄H₄K₂O₆ 117 Bar no Calciumpropionat 260 g/L C₆H₁₀CaO₄ 102 Bar no Kaliumcitrat 640 g/L C₆H₅K₃O₇ · H₂O 102 Bar no Zinksulfat 350 g/L ZnSO₄ 95 Bar H 302 - 318 - 410 Calciumformiat (früher E238) 160 g/L C₂H₂CaO₄ 90 Bar H 318 Auge Natriumsulfat 170 g/L Na⁺ ₂ SO₄ ^2- 87 Bar no Natriumphosphat-Dekahydrat 285 g/L Na₃PO₄*10 H₂O 73 Bar H 315 - 319 - 335 Dinatriumhydrogenphosphat 77 g/L Na₂HPO₄ 53 Bar no Kaliumsulfat 111 g/L K⁺ ₂ SO₄ ^2- 47 Bar no Ammoniumdihydrogenphosphate 36 g/L (NH₄)H₂PO₃ 31 Bar H 319 Auge Ammoniumoxalat 45 q/L (NH₄)₂C₂O₄ 27 Bar H 302 +312 Calciumlaktat 50 g/L C_eH₁₀CaO₆ 17 Bar no Calciumlaktat*5 H2O 66 g/L C_eH₁₀CaO₆ 5 H₂O 16 Bar no Calciumdihydrogenphosphat 18 g/L Ca(HPO₄)₂ 6 Bar H 318 Auge Maqnesiumcarbonat 0 g/L MgCO₃ 0 Bar no Calciumcarbonat 0 g/L CaCO₃ 0 Bar H 302 - 315 - 319 Calciumoxalat 0 g/L CaC₂O₄ 0 Bar 302-312 Calciumphosphat 0 g/L Ca₃(PO₄)₂ 0 Bar no The following saturated salt solutions have a high osmotic pressure, i.e. a particularly high ion concentration and therefore strongly deactivate viruses:

• These include the chlorides and sulfates of ammonium, sodium, potassium, and magnesium, as well as the acetates of ammonium, sodium, potassium, calcium, and magnesium, and the formates of sodium, potassium, and magnesium, citrates, and hydrogen phosphate and urea.

Table 1 Salt ordered by decreasing osmotic pressure. Suitable only for air filters! Salt ordered by decreasing osmotic pressure. Suitable only for air filters Solubility g/L at 20°C formula osmotic pressure in bar no means no hazard symbols zinc chloride 4300g/L ZnCl ₂ 2306 bars H 302 - 314 - 410 potassium formate 2500g/L CHKO ₂ 1450 bars no sodium hydrogen sulfate 2435g/L Na ⁺ HSO ₄ ^2- 1289 bars H318 Potassium Acetate E261 2560g/L _{C2H3KO2 _ _} 1273 bars no cesium fluoride 3670g/L CsF 1176 bars H301-311-314-33 1 ammonium nitrate 2089g/L _{NH4NO3 _} 1144 bars explosive! ammonium fluoride 820g/L _NH4F 1080 bars H301+311+331 ammonium thiocyanate 1600g/L _NH4SCN 1026 bars H 302+312+332 - 318 - 412 lithium chloride 832g/L LiCl 956 bars H 302 - 315 - 31 ammonium acetate 1480g/L _{C2H7NO2 _ _} 935 bars no potassium hydrogen phosphate 1600g/L _{K2HPO4 _} 896 bars no Magnesium chloride E 511 2350g/L MgCl ₂ *6H ₂ O 846 bars no Calcium nitrate E 341 2710g/L Ca(NO ₃ ) ₂ *4H ₂ O 839 bars H272-302-318 ammonium sulfamate 1950g/L NH4 _{( SO3NH2 )} 833 bars H302 lithium bromide 1450g/L LiBr 812 bars H302-315-319-317 potassium propionate 1780g/L _{C3H5KO2 _ _} 773 bars no sodium dihydrogen phosphate 850g/L _{NaH2PO4 _} 690 bars no tartaric acid 1394 g/L _{C4H6O6 _ _} 679 bars H318 eye sodium lactate 1500g/L _{C3H5KaO3 _ _} 652 bars no magnesium acetate 1200g/L Mg(CH3COO _{) 2} 618 bars no ammonium iodide 1770g/L NH ₄ I 595 bars H315-319 potassium carbonate 1120g/L _{K2CO3 _} 593 bars H315-319-335 ferric chloride 920g/L FeCl ₃ 553 bars H 290 - 302 - 315 - 318 cesium chloride 1860g/L CsCl 539 bars H361 ammonium hydrogen phosphate 700g/L ( _{NH4 ) 2HPO3} 517 bars no sodium nitrate 874g/L NaNO ₃ 507 bars H272-319 sodium propionate 995g/L _{C3H5NaO2 _ _} 504 bars H 319 eyes calcium chloride 740g/L CaCl ₂ 492 bars H319 eye ammonium formate (feed additive) 631g/L _{CH5NO2 _} 488 bars H 315 - 319 - 335 potassium sorbate 1400g/L _{C6H7KO2 _ _} 455 bars H 315-319 Skin irritation. Urea E 927b 1100g/L _{CH4N2O _} 447 bars no manganese chloride 723g/L MnCl ₂ 423 bars H 302 - 318 - 373 - 411 copper nitrate 1378g/L Cu(NO ₃ ) ₂ *4H ₂ O 418 bars H272-302-319 iron nitrate 1500g/L Fe(NO ₃ ) ₃ *6H ₂ O 418 bars H272, H302, H319 magnesium chloride 542g/L MgCl ₂ 417 bars no sodium hypophosphinate 744g/L _{NaH2PO2 _} 417 bars no ammonium sulfate 745g/L _NH4 ^* _{2SO42- _} 412 bars no Triammonium citrate E380 1000g/L _{C6H17N3O7 _ _ _} 401 bars no ammonium phosphate 580g/L ( _{NH4 ) 3PO4} 379 bars H315-319-335 ammonium bromide 742g/L NH ₄ Br 369 bars H319 magnesium nitrate 712g/L Mg(NO3 _{) 2} 352 bars H272 Sodium formate (feed additive) 490g/L CHNaO ₂ 351 bars no potassium malate 1000g/L _{C4H4K2O5 _ _ _} 348 bars no ammonium chloride 372g/L _NH4Cl 339 bars H302-319 copper(II) chloride 620g/L CuCl ₂ 338 bars H 302+312 - 315 - 318 - 410 aluminum chloride 450g/L AlCl ₃ 329 bars H314 sodium chloride 358g/L Na ⁺ Cl ^- 298 bars no ammonium carbonate 320g/L ( _{NH4 ) 2CO3} 244 bars H302 Potassium phosphate E 340 508g/L _{K3PO4 _} 233 bars H318-335 potassium chloride 347g/L K ⁺ Cl ^- 227 bars no Sodium Acetate* 3 H2O 613g/L _{C2H3NaO2 * 3H2O _} 220 bars no Potassium sodium tartrate E 337 630g/L _{C4H4KNaO6 _} 219 bars no Sodium acetate E 262a 365g/L _{C2H3NaO2 _ _} 217 bars no sodium 330g/L _{Na2CO3.H2O _ _} 194 bars H319 calcium acetate 400g/L Ca ²⁺ OAc ^- ₂ 185 bars no Calcium Acetate Dihydrate 440g/L Ca ²⁺ OAc' ₂ * 2H ₂ O 166 bars no zinc sulfate heptahydrate 965g/L ZnCl ₂ *H ₂ O 164 bars H 302 - 318 - 410 potassium dihydrogen phosphate 222g/L KH ₂ PO ₄ 159 bars no sodium ascorbate 620g/L _{C6H7NaO6 _ _} 153 bars no potassium nitrate 316g/L KNO ₃ 152 bars H272-319 potassium lactate 400g/L _{C3H5KO 3 _} 152 bars no ammonium bicarbonate 220g/L _{NH4HCO3 _} 136 bars H 302 (Ingestion) aluminum sulfate 360g/L _Al2 (SO4 _{) 3} 128 bars H318 eye disodium tartrate 330g/L _{C4H4Na2O6 _ _ _} 124 bars no magnesium sulfate 300g/L Mg ²⁺ SO ₄ ^2- 122 bars no potassium tartrate 300g/L _{C4H4K2O6 _ _ _} 117 bars no calcium propionate 260g/L _{C6H10CaO4 _ _} 102 bars no potassium citrate 640g/L _{C6H5K3O7H2O _ _ _ _} 102 bars no zinc sulfate 350g/L ZnSO ₄ 95 bars H 302 - 318 - 410 Calcium formate (formerly E238) 160g/L _{C2H2CaO4 _ _} 90 bars H318 eye sodium sulfate 170g/L Na ⁺ ₂ SO ₄ ^2- 87 bar no Sodium phosphate decahydrate 285g/L _{Na3PO4 * 10H2O} 73 bars H 315 - 319 - 335 disodium hydrogen phosphate 77g/L Na ₂ HPO ₄ 53 bars no potassium sulfate 111g/L ^{K +} _{2SO42- _} 47 bars no ammonium dihydrogen phosphates 36g/L ( _{NH4 ) H2PO3} 31 bars H319 eye ammonium oxalate 45 q/L _{( NH4 ) 2C2O4} 27 bars H302 +312 calcium lactate 50g/L _{CeH10CaO6 _ _} 17 bar no Calcium lactate*5 H2O 66g/L _{CeH10CaO65H2O _ _ _} 16 bars no calcium dihydrogen phosphate 18g/L Ca(HPO ₄ ) ₂ 6 bar H318 eye magnesium carbonate 0g/L MgCO ₃ 0 bar no calcium carbonate 0g/L CaCO ₃ 0 bar H 302 - 315 - 319 calcium oxalate 0g/L _{CaC2O4 _} 0 bar 302-312 calcium phosphate 0g/L _Ca3 (PO4 _{) 2} 0 bar no

6.1.2.2 The following salts are harmless to health and are therefore suitable for treating room air

Table 2: Salts that are harmless to health and therefore suitable for the treatment of room air and sorted according to falling osmotic pressure Salt suitable for room air purification and mask Solubility g/L at 20°C formula osmotic pressure in bar hy = hygroscopic potassium formate 2500 CHKO ₂ 1450 bars hey Potassium Acetate E261 2560 _{C2H3KO2 _ _} 1273 bars hey ammonium acetate 1480 _{C2H7NO2 _ _} 935 bars hey potassium hydrogen phosphate 1600 _{K2HPO4 _} 896 bars Magnesium chloride E 511 2350 MgCl ₂ *6H ₂ O 846 bars hey potassium propionate 1780 _{C3H5KO2 _ _} 773 bars hey sodium dihydrogen phosphate 850 _{NaH2PO4 _} 690 bars sodium lactate 1500 _{C3H5KaO3 _ _} 652 bars magnesium acetate 1200 Mg(CH3COO _{) 2} 618 bars ammonium hydrogen phosphate 700 ( _{NH4 ) 2HPO3} 517 bars Urea E 927b 1100 _{CH4N2O _} 447 bars hey magnesium chloride 542 MgCl ₂ 417 bars hey sodium hypophosphinate 744 _{NaH2PO2 _} 417 bars ammonium sulfate 745 NH ₄ ⁺ ₂ SO ₄ ^2- 412 bars hey Triammonium citrate E380 1000 _{C6H17N3O7 _ _ _} 401 bars hey sodium formate 490 CHNaO ₂ 351 bars hey potassium malate 1000 _{C4H4K2O5 _ _ _} 348 bars sodium chloride 358 Na ⁺ Cl ^- 298 bars hey potassium chloride 347 K ⁺ Cl ^- 227 bars hey sodium acetate 613 _{C2H3NaO2 * 3H2O _} 220 bars Potassium sodium tartrate E 337 630 _{C4H4KNaO6 _ _} 219 bars hey Sodium acetate E 262a 365 _{C2H3NaO2 _ _} 217 bars hey calcium acetate 400 Ca ²⁺ OAC ^- ₂ 185 bars hey Calcium Acetate Dihydrate 440 Ca ²⁺ OAc ^- ₂ * 2H ₂ O 166 bars potassium dihydrogen phosphate 222 KH ₂ PO ₄ 159 bars sodium ascorbate 620 _{C6H7NaO6 _ _} 153 bars potassium lactate 400 _{C3H5KO 3 _} 152 bars hey disodium tartrate 330 _{C4H4Na2O6 _ _ _} 124 bars magnesium sulfate 300 Mg ²⁺ SO ₄ ^2- 122 bars hey potassium tartrate 300 _{C4H4K2O6 _ _ _} 117 bars calcium propionate 260 _{C6H10CaO4 _ _} 102 bars potassium citrate 640 _{C6H5K3O7H2O _ _ _ _} 102 bars sodium sulfate 170 Na ⁺ ₂ SO ₄ ^2- 87 bar hey disodium hydrogen phosphate 77 Na ₂ HPO ₄ 53 bars potassium sulfate 111 ^{K +} _{2SO42- _} 47 bars hey calcium lactate 50 _{C6H10CaO6 _ _} 17 bar hey Calcium lactate*5 H2O 66 _{C6H10CaO65H2O _ _ _} 16 bars

6.1.2.3 The salt must be easily soluble in water + hygroscopic

Hygroscopic salts get the water from the air and are subject to constant transformation processes: They crystallize and dissolve in their own salt water even with small changes in the room air conditions. It is precisely these processes that destroy viruses.

Deliquescent salts

Deliquescent salts and their mixtures have the following advantage: the salts dissolve in moist air, only to crystallize again in somewhat drier air. Any crystallization can mechanically destroy viruses. If mixtures of salt with different equilibrium moisture levels are used, this virus-destroying crystallization process can take place at any relative humidity.

must be observed. That deliquescent salts influence each other in their equilibrium moisture content according to Raoult's law. As a result, the equilibrium moisture content of one salt is lowered by adding another.

The situation is also complicated by the fact that salts exchange their ions and also form mixed crystals ³²³³ .

1. 1. Zuerst wird die Oberfläche des Salzkristalls monomolekular mit einer Wasserschicht belebt.
2. 2. Dann kann eventuell durch Wasseraufnahme im Kristall eine Hydratisierung und Umkristallisation des Kristalls unter starker Volumenvergrößerung stattfinden.
3. 3. Dann kann der Kristall bei weiter steigender Luftfeuchtigkeit unter Wasseraufnahme zerfließen (deliqueszieren).

The interaction of the salts with the humidity runs through several stages:

1. 1. First, the surface of the salt crystal is revitalized monomolecularly with a layer of water.
2. 2. Hydration and recrystallization of the crystal with a strong increase in volume can then possibly take place due to water absorption in the crystal.
3. 3. The crystal can then melt (deliquesce) as the air humidity continues to rise while absorbing water.

• Regeln der Luftfeuchtigkeit durch diese Salze, Abfangen von Staub, Feuchthalten von Lebensmitteln, Latenzwärmespeicherung.

Tabelle 3: Salze sortiert nach Deliqueszenzfeuchte Salz sortiert nach Deliqueszenz Löslichkeit g/L bei 20°C Formel osmotischer Druck in Bar Gefahren Gleichgewichtsfeuchte Kaliumsulfat 111 g/L K⁺ ₂ SO₄ ^2- 47 Bar no 96,40 % Natriumsulfat 170 g/L Na⁺ ₂ SO₄ ^2- 87 Bar no 95,60 % Kaliumnitrat 316 g/L KNO₃ 152 Bar H 272-319 93,70 % Calciumdihydrogenphosphat 18 g/L Ca(HPO₄)₂ 6 Bar H 318 Auge 93,60 % Ammoniumdihydrogenphosphate 36 g/L (NH₄)H₂PO₃ 31 Bar H 319 Auge 91,60 % Magnesiumsulfat 300 q/L Mq²⁺ SO₄ ^{2 -} 122 Bar no 91,30 % Calciumformiat (früher E238) 160 g/L C₂H₂CaO₄ 90 Bar H 318 Auge 89,90 % Kaliumchlorid 347 g/L K⁺ Cl^- 227 Bar no 84,00 % Ammoniumhydrogenphosphat 700 g/L (NH₄)₂HPO₃ 517 Bar no 82,50 % Ammoniumchlorid 372 g/L NH₄Cl 339 Bar H 302-319 77,20 % Natriumchlorid 358 g/L Na⁺ Cl^- 298 Bar no 75,40 % Harnstoff E 927b 1100 g/L CH₄N₂O 447 Bar no 72,50 % Natriumnitrat 874 g/L NaNO₃ 507 Bar H 272-319 72,40 % Natriumcarbonat 330 g/L Na₂CO₃·H₂O 194 Bar H 319 71,00 % Natriumformiat (Futterzusatz) 490 g/L CHNaO₂ 351 Bar no 67,30 % Ammoniumnitrat 2089 g/L NH₄NO₃ 1144 Bar explosiv! 59,40 % Ammoniumformiat (Futterzusatz) 631 g/L CH₅NO₂ 488 Bar H 315-319-335 59,10 % Calciumnitrat E 341 2710 g/L Ca(NO₃)₂*4 H₂O 839 Bar H 272-302-318 53,06 % Natriumhydrogensulfat 2435 g/L Na⁺ HSO₄ ^2- 1289 Bar H 318 52,00 % Kaliumformiat 2500 g/L CHKO₂ 1450 Bar no 51,50 % Ammoniumsulfat 745 g/L NH₄ ⁺ ₂ SO₄ ^2- 412 Bar no 40,00 % Magnesiumchlorid 542 g/L MgCl₂ 417 Bar no 33,10 % Magnesiumchlorid E 511 2350 g/L MgCl₂*6 H₂O 846 Bar no 33,10 % Calciumchlorid 740 g/L CaCl₂ 492 Bar H 319 Auge 33,10 % Ammoniumacetat 1480 q/L C₂H₇NO₂ 935 Bar no 30,00 % Magnesiumcitrat Mg₃(C₆H₅O₇)₂ H 315-319-335 27,00 % Ammoniumiodid 1770 g/L NH₄I 595 Bar H 315-319 25,00 % Natriumacetat E 262a 365 g/L C₂H₃NaO₂ 217 Bar no 20,00 % Calciumoxalat 0 g/L CaC₂O₄ 0 Bar 302-312 20,00 % Ammoniumbromid 742 g/L NH₄Br 369 Bar H 319 17,00 % Maqnesiumcarbonat 0 g/L MgCO₃ 0 Bar no 12,00 % Lithiumchlorid 832 g/L LiCl 956 Bar H 302-315-319 11,30 % Lithiumbromid 1450 g/L LiBr 812 Bar H 302-315-319-317 6,61 % Ammoniumcarbonat 320 g/L (NH₄)₂CO₃ 244 Bar H 302 5,00 % Cäsiumfluorid 3670 g/L CsF 1176 Bar H 301-311-314-331 3,00 % Eisen(III)chlorid 920 g/L FeCl₃ 553 Bar H 290-302-315-318 2,00 % Magnesiumacetat³⁴ 1200 g/L Mg(CH₃COO)₂ 618 Bar no 2,00 % Calciumacetat 400 g/L Ca²⁺ OAc^- ₂ 185 Bar no 70,00 % Magnesiumnitrat 712 g/L Mg(NO₃)₂ 352 Bar H 272 2,00 % Calciumphosphat 0 g/L Ca₃(PO₄)₂ 0 Bar no 2,00 % Triammoniumcitrat E380 1000 g/L C₆H₁₇N₃O₇ 401 Bar no 2,00 % Ammoniumoxalat 45 g/L (NH₄)₂C₂O₄ 27 Bar H 302 +312 2,00 % Tabelle 4: deliqueszente und effloreszente Salz ohne Gefahrstoffkennzeichnung, geeignet für Raumluft- und Maskenbehandlung Salz ohne Gefahrstoffkennzeichen, geeignet für Raumluft- und Maskenbehandlung Löslichkeit g/L bei 20°C Formel osmotischer Druck in Bar Gefahren Gleichgewichtsfeuchte Kaliumsulfat 111 g/L K⁺ ₂ SO₄ ^2- 47 Bar no 96,40 % Natriumsulfat 170 g/L Na⁺ ₂ SO₄ ^2- 87 Bar no 95,60 % Magnesiumsulfat 300 g/L Mg²⁺ SO₄ ^2- 122 Bar no 91,30 % Kaliumchlorid 347 g/L K⁺ Cl^- 227 Bar no 84,00 % Ammoniumhydrogenphosphat 700 g/L (NH₄)₂HPO₃ 517 Bar no 82,50 % Natriumchlorid 358 g/L Na⁺ Cr 298 Bar no 75,40 % Harnstoff 1100 g/L CH₄N₂O 447 Bar no 72,50 % Natriumformiat 490 g/L CHNaO₂ 351 Bar no 67,30 % Kaliumformiat 2500 g/L CHKO₂ 1450 Bar no 51,50 % Ammoniumsulfat 745 g/L NH₄ ⁺ ₂ SO₄ ^2- 412 Bar no 40,00 % Magnesiumchlorid 542 g/L MgCl₂ 417 Bar no 33,10 % Magnesiumchlorid 2350 g/L MgCl₂*6 H₂O 846 Bar no 33,10 % Ammoniumacetat 1480 g/L C₂H₇NO₂ 935 Bar no 30,00 % Natriumacetat 365 g/L C₂H₃NaO₂ 217 Bar no 20,00 % Magnesiumcarbonat 0 g/L MgCO₃ 0 Bar no 12,00 % Magnesiumacetat 1200 g/L Mg(CH₃COO)₂ 618 Bar no 70,00 % Calciumacetat³⁵ 400 g/L Ca²⁺ OAc'₂ 185 Bar no 70,00 % Calciumphosphat 0 g/L Ca₃(PO₄)₂ 0 Bar no 2,00 % Triammoniumcitrat E380 1000 g/L C₆H₁₇N₃O₇ 401 Bar no 2,00 % Tabelle 5: Deliqueszente Salze geeignet für Luftreinigung durch Wassernebel und Schutzmaske und für die Imprägnierung von Raumluftfilter in Räumen mit passender Luftfeuchtigkeit. Deliqueszente Salze geeignet für Luftreinigung durch Wassernebel und Schutzmaske Löslichkeit g/L bei 20°C Formel osmotischer Druck in Bar Gleichgewichtsfeuchte Kaliumsulfat 111 g/L K⁺ ₂ S₄ ^2- 47 Bar 96,40 % Natriumsulfat 170 g/L Na⁺ ₂ SO₄ ^2- 87 Bar 95,60 % Magnesiumsulfat 300 g/L Mg²⁺ SO₄ ^2- 122 Bar 91,30 % Kaliumchlorid 347 g/L K⁺ Cl^- 227 Bar 84,00 % Ammoniumhydrogenphosphat 700 g/L (NH₄)₂HPO₃ 517 Bar 82,50 % Natriumchlorid 358 g/L Na⁺ Cl^- 298 Bar 75,40 % Harnstoff E 927b 1100 g/L CH₄N₂O 447 Bar 72,50 % Natriumformiat (Futterzusatz) 490 g/L CHNaO₂ 351 Bar 67,30 % Kaliumformiat 2500 g/L CHKO₂ 1450 Bar 51,50 % Ammoniumsulfat 745 g/L NH₄ ⁺ ₂ SO₄ ^2- 412 Bar 40,00 % Magnesiumchlorid 542 g/L MgCl₂ 417 Bar 33,10 % Magnesiumchlorid E 511 2350 g/L MgCl₂*6 H₂O 846 Bar 33,10 % Ammoniumacetat 1480 g/L C₂H₇NO₂ 935 Bar 30,00 % Natriumacetat E 262a 365 g/L C₂H₃NaO₂ 217 Bar 20,00 % Tabelle 6: Sich verflüssigende Kaliumsalze Kaliumsalze ohne Gefahrstoffkennzeichen, geeignet für Raumluft- und Maskenbehandlunq Löslichkeit g/L bei 20°C Formel osmotischer Druck in Bar Gefahren Gleichgewichtsfeuchte Kaliumsulfat 111 g/L K⁺ ₂ SO₄ ^2- 47 Bar no 96,40 % Kaliumchlorid 347 g/L K⁺ Cl^- 227 Bar no 84,00 % Harnstoff 1100 g/L CH₄N₂O 447 Bar no 72,50 % Kaliumformiat 2500 g/L CHKO₂ 1450 Bar no 51,50 % Mischung aus obigen Salzen 30,20 % Harnstoff + Kaliumformiat 37,30 % K₂SO₄, KCl, K-Formiat 41,70 % Kaliumformiat + K₂SO₄ 49,60 % These processes have found the following technical applications:

• These salts regulate the humidity in the air, trapping dust, keeping food moist, latent heat storage.

Table 3: Salts sorted by deliquescent moisture Salt sorted by deliquescence Solubility g/L at 20°C formula osmotic pressure in bar Driven equilibrium moisture potassium sulfate 111g/L ^{K +} _{2SO42- _} 47 bars no 96.40% sodium sulfate 170g/L Na ⁺ ₂ SO ₄ ^2- 87 bar no 95.60% potassium nitrate 316g/L KNO ₃ 152 bars H272-319 93.70% calcium dihydrogen phosphate 18g/L Ca(HPO ₄ ) ₂ 6 bar H318 eye 93.60% ammonium dihydrogen phosphates 36g/L ( _{NH4 ) H2PO3} 31 bars H319 eye 91.60% magnesium sulfate 300q/L Mq ²⁺ SO ₄ ^{2 -} 122 bars no 91.30% Calcium formate (formerly E238) 160g/L _{C2H2CaO4 _ _} 90 bars H318 eye 89.90% potassium chloride 347g/L K ⁺ Cl ^- 227 bars no 84.00% ammonium hydrogen phosphate 700g/L ( _{NH4 ) 2HPO3} 517 bars no 82.50% ammonium chloride 372g/L _NH4Cl 339 bars H302-319 77.20% sodium chloride 358g/L Na ⁺ Cl ^- 298 bars no 75.40% Urea E 927b 1100g/L _{CH4N2O _} 447 bars no 72.50% sodium nitrate 874g/L NaNO ₃ 507 bars H272-319 72.40% sodium 330g/L _{Na2CO3.H2O _ _} 194 bars H319 71.00% Sodium formate (feed additive) 490g/L CHNaO ₂ 351 bars no 67.30% ammonium nitrate 2089g/L _{NH4NO3 _} 1144 bars explosive! 59.40% ammonium formate (feed additive) 631g/L _{CH5NO2 _} 488 bars H315-319-335 59.10% Calcium nitrate E 341 2710g/L Ca(NO ₃ ) ₂ *4H ₂ O 839 bars H272-302-318 53.06% sodium hydrogen sulfate 2435g/L Na ⁺ HSO ₄ ^2- 1289 bars H318 52.00% potassium formate 2500g/L CHKO ₂ 1450 bars no 51.50% ammonium sulfate 745g/L NH ₄ ⁺ ₂ SO ₄ ^2- 412 bars no 40.00% magnesium chloride 542g/L MgCl ₂ 417 bars no 33.10% Magnesium chloride E 511 2350g/L MgCl ₂ *6H ₂ O 846 bars no 33.10% calcium chloride 740g/L CaCl ₂ 492 bars H319 eye 33.10% ammonium acetate 1480 q/L _{C2H7NO2 _ _} 935 bars no 30.00% magnesium citrate _{Mg3 ( C6H5O7 ) 2} H315-319-335 27.00% ammonium iodide 1770g/L NH ₄ I 595 bars H315-319 25.00% Sodium acetate E 262a 365g/L _{C2H3NaO2 _ _} 217 bars no 20.00% calcium oxalate 0g/L _{CaC2O4 _} 0 bar 302-312 20.00% ammonium bromide 742g/L NH ₄ Br 369 bars H319 17.00% magnesium carbonate 0g/L MgCO ₃ 0 bar no 12.00% lithium chloride 832g/L LiCl 956 bars H302-315-319 11.30% lithium bromide 1450g/L LiBr 812 bars H302-315-319-317 6.61% ammonium carbonate 320g/L ( _{NH4 ) 2CO3} 244 bars H302 5.00% cesium fluoride 3670g/L CsF 1176 bars H301-311-314-331 3.00% ferric chloride 920g/L FeCl ₃ 553 bars H290-302-315-318 2.00% Magnesium acetate ³⁴ 1200g/L Mg(CH3COO _{) 2} 618 bars no 2.00% calcium acetate 400g/L Ca ²⁺ OAc ^- ₂ 185 bars no 70.00% magnesium nitrate 712g/L Mg(NO3 _{) 2} 352 bars H272 2.00% calcium phosphate 0g/L _Ca3 (PO4 _{) 2} 0 bar no 2.00% Triammonium citrate E380 1000g/L _{C6H17N3O7 _ _ _} 401 bars no 2.00% ammonium oxalate 45g/L _{( NH4 ) 2C2O4} 27 bars H302 +312 2.00% Table 4: deliquescent and efflorescent salts without hazardous substance labeling, suitable for room air and mask treatment Salt without a hazardous substance label, suitable for room air and mask treatment Solubility g/L at 20°C formula osmotic pressure in bar Driven equilibrium moisture potassium sulfate 111g/L ^{K +} _{2SO42- _} 47 bars no 96.40% sodium sulfate 170g/L Na ⁺ ₂ SO ₄ ^2- 87 bar no 95.60% magnesium sulfate 300g/L Mg ²⁺ SO ₄ ^2- 122 bars no 91.30% potassium chloride 347g/L K ⁺ Cl ^- 227 bars no 84.00% ammonium hydrogen phosphate 700g/L ( _{NH4 ) 2HPO3} 517 bars no 82.50% sodium chloride 358g/L Na ⁺ Cr 298 bars no 75.40% urea 1100g/L _{CH4N2O _} 447 bars no 72.50% sodium formate 490g/L CHNaO ₂ 351 bars no 67.30% potassium formate 2500g/L CHKO ₂ 1450 bars no 51.50% ammonium sulfate 745g/L NH ₄ ⁺ ₂ SO ₄ ^2- 412 bars no 40.00% magnesium chloride 542g/L MgCl ₂ 417 bars no 33.10% magnesium chloride 2350g/L MgCl ₂ *6H ₂ O 846 bars no 33.10% ammonium acetate 1480g/L _{C2H7NO2 _ _} 935 bars no 30.00% sodium acetate 365g/L _{C2H3NaO2 _ _} 217 bars no 20.00% magnesium carbonate 0g/L MgCO ₃ 0 bar no 12.00% magnesium acetate 1200g/L Mg(CH3COO _{) 2} 618 bars no 70.00% Calcium Acetate ³⁵ 400g/L Ca ²⁺ OAc' ₂ 185 bars no 70.00% calcium phosphate 0g/L _Ca3 (PO4 _{) 2} 0 bar no 2.00% Triammonium citrate E380 1000g/L _{C6H17N3O7 _ _ _} 401 bars no 2.00% Table 5: Deliquescent salts suitable for air purification using water mist and protective masks and for impregnating room air filters in rooms with suitable humidity. Deliquescent salts suitable for air purification with water mist and protective mask Solubility g/L at 20°C formula osmotic pressure in bar equilibrium moisture potassium sulfate 111g/L K ⁺ ₂ S ₄ ^2- 47 bars 96.40% sodium sulfate 170g/L Na ⁺ ₂ SO ₄ ^2- 87 bar 95.60% magnesium sulfate 300g/L Mg ²⁺ SO ₄ ^2- 122 bars 91.30% potassium chloride 347g/L K ⁺ Cl ^- 227 bars 84.00% ammonium hydrogen phosphate 700g/L ( _{NH4 ) 2HPO3} 517 bars 82.50% sodium chloride 358g/L Na ⁺ Cl ^- 298 bars 75.40% Urea E 927b 1100g/L _{CH4N2O _} 447 bars 72.50% Sodium formate (feed additive) 490g/L CHNaO ₂ 351 bars 67.30% potassium formate 2500g/L CHKO ₂ 1450 bars 51.50% ammonium sulfate 745g/L NH ₄ ⁺ ₂ SO ₄ ^2- 412 bars 40.00% magnesium chloride 542g/L MgCl ₂ 417 bars 33.10% Magnesium chloride E 511 2350g/L MgCl ₂ *6H ₂ O 846 bars 33.10% ammonium acetate 1480g/L _{C2H7NO2 _ _} 935 bars 30.00% Sodium acetate E 262a 365g/L _{C2H3NaO2 _ _} 217 bars 20.00% Table 6: Liquefying potassium salts Potassium salts without a hazardous substance label, suitable for room air and mask treatment Solubility g/L at 20°C formula osmotic pressure in bar Driven equilibrium moisture potassium sulfate 111g/L ^{K +} _{2SO42- _} 47 bars no 96.40% potassium chloride 347g/L K ⁺ Cl ^- 227 bars no 84.00% urea 1100g/L _{CH4N2O _} 447 bars no 72.50% potassium formate 2500g/L CHKO ₂ 1450 bars no 51.50% Mixture of above salts 30.20% urea + potassium formate 37.30% K ₂ SO ₄ , KCl, K formate 41.70% Potassium formate + K ₂ SO ₄ 49.60%

In this way, a solution of salts can be produced from which magnesium sulphate crystallizes, starting at a humidity of approx. 90%, then sodium sulphate and sodium chloride at 80% and calcium chloride rid at 30%. However, the mixing ratio of the components can only be determined experimentally and cannot be easily calculated. ³⁶ , ³⁷ Table 7: Liquefying ammonium salts Ammonium salts without a hazardous substance label, suitable for room air and mask treatment Solubility g/L at 20°C formula osmotic pressure in bar Driven Relative humidity when the liquefaction of the salt occurs ammonium hydrogen phosphate 700g/L ( _{NH4 ) 2HPO3} 517 bars no 82.50% Urea E 927b 1100g/L _{CH4N2O _} 447 bars no 72.50% ammonium sulfate 745g/L NH ₄ ⁺ ₂ SO ₄ ^2- 412 bars no 40.00% ammonium acetate 1480g/L _{C2H7NO2 _ _} 935 bars no 30.00% _{NH4 ) 2HPO3} , _{CH4N2O , ( NH4 ) 2SO4 , C2H7NO2} 6.70% _{NH4 ) 2HPO3} , _{CH4N2O ,} ( _{NH4 ) 2SO4} 22.40% Table 8: Liquefying chlorides Chlorides without a hazardous substance label, suitable for room air and mask treatment Solubility g/L at 20°C formula osmotic pressure in bar Driven equilibrium moisture potassium chloride 347 q/L K ⁺ Cl ^- 227 bars no 84.00% sodium chloride 358g/L Na ⁺ Cl ^- 298 bars no 75.40% Urea E 927b 1100g/L _{CH4N2O _} 447 bars no 72.50% magnesium chloride 542g/L MgCl ₂ 417 bars no 33.10% Magnesium chloride E 511 2350g/L MgCl ₂ *6H ₂ O 846 bars no 33.10% _KCl , NaCl, _CH4N2O , _MgCl2 15.20% KCl, NaCl, MgCl ₂ 21.00% KCl, MgCl ₂ 27.80% KCl, NaCl Literature value: 72% 63.30% NaCl, MgCl ₂ ³⁸ Table 9: Liquefying sulfates Sulfates without a hazardous substance label, suitable for room air and mask treatment Solubility g/L at 20°C formula osmotic pressure in bar Driven equilibrium moisture potassium sulfate 111g/L ^{K +} _{2SO42- _} 47 bars no 96.40% sodium sulfate ³⁹ 170g/L Na ⁺ ₂ SO ₄ ^2- 87 bar no 95.60% magnesium sulfate 300g/L Mg ²⁺ SO ₄ ^2- 122 bars no 91.30% Urea E 927b 1100g/L _{CH4N2O _} 447 bars no 72.50% ammonium sulfate 745g/L NH ₄ ⁺ ₂ SO ₄ ^2- 412 bars no 35.50% Mixture of Na ₂ SO ₄ + (NH ₄ ) ₂ SO ₄ 35.90% Na ₂ SO ₄ +MgSO ₄ + (NH ₄ ) ₂ SO ₄ 24.50% Na ₂ SO ₄ + (NH ₄ ) ₂ SO ₄ + urea 26.00% Mixture of all of the above salts 22.90%

The seawater air, ie the sea spray, is very well simulated by mixtures of NaCl and MgCl ₂ . This mixture is the second most common aerosol in the atmosphere after ammonium sulfate-water aerosols. The sodium chloride crystallizes first in the center of the droplet and - above a certain size - forms the optimal nucleus for the crystallization of the magnesium chloride 6-hydrate (MgCl ₂ *6H ₂ O). This crystallization occurs when the humidity drops above a certain relative humidity (ERH _Start ). The mixing ratio of NaCl to MgCl ₂ determines this ERH _start value. For example, a common salt/magnesium chloride mixture crystallizes at 40 to 35% relative humidity. The pure MgCl ₂ *4 H ₂ O only crystallizes at a relative humidity of 10 to 3%. Pure table salt crystallizes from its solution at a humidity of 46%. This deliquescence point can be greatly reduced by adding magnesium chloride. ⁴⁰

6.1.2.4 Salts with different crystal water content

Some salts exist with different waters of crystallization and recrystallize with increasing relative humidity with a change in volume in the more hydrated stage. Here, too, the virus is crushed, although not to the extreme extent of recrystallization. These salts include magnesium sulphate with a crystal water content of 1 to 11 ⁴¹ and calcium nitrate (crystal water content 0, 2, 3, 4) ⁴² , which melts at 25 °C as tetrahydrate and a relative humidity of over 50% in its own crystal water ⁴³ .

"The phase transformations from calcium nitrate tetrahydrate to the other two hydrate stages and to anhydrous calcium nitrate only take place at relative humidity levels of 22%, 13% and 9%, respectively." ⁴⁴

The various phases of calcium chloride ⁴⁵ are hygroscopic salts with comparatively low deliquescence moisture levels. At room temperature, the present calcium chloride hexahydrate has a deliquescence moisture content of about 30%. The deliquescence behavior is temperature-dependent insofar as the deliquescence moisture levels are lower at higher temperatures. At a temperature of 20 °C and a relative humidity of 18 %, the calcium chloride hexahydrate is dehydrated and converted into calcium chloride tetrahydrate. At 9% RH or 6% RH, the di- or monohydrate is formed.

6.1.3 Possible combinations of components

All combinations of salt, surfactant and solvent can be useful, with the most important component always being the salt.

A surfactant can be added to the salt so that it adheres better to a water-repellent surface (e.g. polypropylene).

Since the salt only shows its strongest antiviral effect in connection with the formation of crystals, it should be saturated in a solvent. Alternatively, water could be added to the salt again and again, which then evaporates again and causes the salt to crystallize.

6.1.3.1 hygroscopic salt and water

The advantage is that once the water has evaporated, the salt can easily be completely removed by suction.

6. 1.3.2 Salt solution and high-boiling liquid

The use of a high-boiling liquid to which viruses “stick” is advantageous.

In addition, salt also adheres better to the surface due to the high-boiling liquid. Since high-boiling liquids only evaporate very slowly or hardly at all, their effect as virus scavengers is long-lasting.

6.1.3.3 Salt solution and hygroscopic liquid

Hygroscopic liquids often have the effect that they promote the dissolution of the salt when the air humidity rises or, to some extent, prevent the formation of supersaturated salt solutions and thus enable continuous crystallization over a wide range of relative air humidity. An example of this is glycerin, which has the effect that ammonium sulfate promotes efflorescence or deliquescence over almost the entire relative humidity range.

6.1.3.4 Salt and Water and Surfactant

A mixture of salt and water and surfactant (Tween 20) has proven its worth for masks made of cotton and especially polypropylene when impregnating and wearing them.

It is favorable if either the salt and/or the surfactant and/or the liquid are hygroscopic and thus allow the salt to dissolve and crystallize out over a wide relative humidity range.

6.1.3.5 hygroscopic salts

Table salt (sodium chloride) with the anti-caking agent potassium ferrocyanide (potassium hexacyanoferrate (II)) is suitable because it is easily available even in the food trade and the potassium hexacyanoferrate has no disruptive effect on crystallization. Table salt with other anti-caking agents is less favorable, as these lead to cloudy solutions with poorly soluble substances that could clog the nozzle of the atomizer when atomized.

• Kaliumchlorid, Kaliumsulfat, Kaliumtartrat, Kaliumsorbat, Calciumacetat, Ammoniumnitrat (nur bedingt, da leicht flüchtig und nicht geeignet für Masken), Natriumascorbat, Natriumlactat und Dinatriumtartrat.

Sodium chloride can be replaced with:

• Potassium chloride, potassium sulfate, potassium tartrate, potassium sorbate, calcium acetate, ammonium nitrate (only to a limited extent, as it is highly volatile and not suitable for masks), sodium ascorbate, sodium lactate and disodium tartrate.

Suitable hygroscopic salts are: sodium sulphate, sodium propiate, potassium propiate, calcium lactate and potassium lactate, ammonium sulphate.

Sodium chloride solutions with glycerin added, as well as ammonium sulfate and glycerin (dissolved in a 1:1 mass ratio in water (effective in the relative humidity range from 0 to 80%)), saturated, aqueous salt solutions of disodium tartrate, sodium malonate (for the relative humidity range from 0 -90%), sodium tartrate, ammonium tartrate, sodium acetate (suitable for humidity above 40%) and magnesium chloride (over the entire humidity range 0 - 100%).

6.1.3.5.1 Preservatives in the impregnation solution

The addition of preservative to the impregnation solution is unnecessary due to the use of a concentrated salt solution, since the saturated salt solution prevents the growth of microorganisms.

6.1.3.6 Solvents in the impregnation solution

6.1.3.6.1 Water

Water as a solvent can in principle be used as a solvent for the salts used. Water is also suitable for diluting the other proposed solvents.

Distilled water or tap water can be used if it is not too hard. Sterilization is achieved by heating the saturated salt-surfactant mixture.

6.1.3.6.2 Glycerin

Glycerin (E 422) as a solvent has the advantage that it is hygroscopic and hardly evaporates due to its high boiling point of 290 °C. Impregnation with a salt-glycerine mixture remains moist for weeks, with the glycerine evaporating only imperceptibly and ensuring constant crystal formation in a saturated salt solution.

Glycerin is permitted in both medical products and food.

6.1.3.6.3 Polyethylene Glycol (PEG, Macrogol)

Polyethylene glycol (E 1521) as a solvent has a very high boiling point and is hygroscopic and toxicologically harmless.

Polyglycols, polyethylene glycol, PEG for short, also called polyethylene glycol with an average molecular weight between 200 g/mol and 400 g/mol are non-volatile, hygroscopic liquids ⁴⁶ . Solid PEG with a molecular weight above 600 is water soluble and thus suitable. Another advantage is that the PEGs are biodegradable up to a molar mass of 1500. ⁴⁷ Of these liquids, ethylene glycol and diethylene glycol should be rejected for health reasons.

6.1.3.6.4 1,2-Propanediol ⁴⁸ :

1,2 Propanediol (E 1520) as a solvent is also used alongside glycerine in e-cigarettes. The boiling temperature is relatively high at 188 °C. Furthermore, 1,2 propanediol is non-toxic, hygroscopic and therefore forms condensation nuclei for water droplets in the air.

1.2 Propanediol is approved for addition to food and pharmaceuticals.

The occasional occurrence of allergic reactions is probably due to contamination with 1,3-propanediol.

Propanediol has the advantage that it deactivates the proteins of the viruses through its chaotropic effect.

6.1.3.6.5 Effect of humidity on a salt-glycerol-water mixture

With the ternary mixture of sodium chloride with glycerol and water, it must be noted that the solubility of sodium chloride drops sharply with increasing glycerol content from 35 g NaCl 1100 mL water to 6 g / 100 mL glycerol.

However, glycerin has the advantage that it is hygroscopic over the entire humidity range and reacts quickly to changing humidity levels.

This also applies in particular to an ammonium sulphate-glycerine mixture, which effloresces over the entire range of relative humidity.

This interaction exists for a large number of salt solutions

6.1.3.7 Staining the impregnation solution to visualize the protective effect.

The coloring of the impregnation solution serves to better recognize the complete impregnation of fabrics, face masks or gloves. The staining serves to distinguish between an impregnated and a non-impregnated surface and thus to identify the protection against infection.

6.1.3.7.1 Criteria for suitable dyes in the impregnation solution:

Dyes are used that do not pose a health risk. This means that many of the colorants permitted under food law can be used.

All azoes, all aminos and all triphenylmethanes are not used due to allergy-triggering or carcinogenic effects.

• Günstig sind naturnahe oder natürlicher von kontrastreiche, intensive Farbe

In addition, the dyes must be lightfast and compatible with the ingredients of the impregnation solution:

• Favorable are near-natural or more natural of high-contrast, intense color

6.1.3.7.2 Water-soluble e

Riboflavin 5'-phosphate (E 101, E 101a)
Chlorophyllin (E140, E141) (This is interesting because it binds carcinogenic heterocyclic amines) ⁴⁹
Indigotine (E 132)
Anthocyanins (E 163)
Betanine (E162)

For personal use, coloring with hibiscus tea and other plant colors is also possible.

6.1.3.7.3 Fat-soluble dyes that form an emulsion with the surfactant.

Lycopene (E 160 d)
Carotene (E 160 af)

6.1.4 Preparation of the impregnation solution

1. 1. Wasser dient zum Auflösen, Verdünnen und gleichmäßigen Auftragen der Komponenten: So ist das Auftragen einer gesättigten Salzlösung auf die Maske nicht sinnvoll, wenn dadurch die Maske zu steif und luftundurchlässig wird. In diesem Fall muss die Salzlösung mit Wasser verdünnt werden oder weniger aufgesprüht werden
2. 2. Salz als gegen Viren wirksame Komponente. Die Salze sollen möglichst gut wasserlöslich eventuell hygroskopisch und ihre Löslichkeit eventuell stark temperaturabhängig sein. Die Auswahl der Salze richtet sich nach dem Einsatzort und der dort herrschenden, relativen Luftfeuchtigkeit.
   1. a. In Mund-Nasenschutz- Masken kommen wegen der dort herrschenden, hohen relativen Luftfeuchtigkeit der Atemluft Salze mit einer hohen Deliqueszenzfeuchte in Frage: Also z.B. Kochsalz.
   2. b. In Raumluftfiltern mit wechselnder relativer Luftfeuchtigkeit müssen Salzlösungen verwendet werden, bei denen über einen möglichst großen Bereich der Luftfeuchtigkeit die Kristallisations- und die Auflösungsvorgänge auftreten.
3. 3. Das Tensid z.B. Tween 20 muss vor allem bei der Imprägnierung von unpolaren Materialen eingesetzt werden, um eine Benetzung der Oberfläche zu sichern. Für diese Benetzung ist nur eine geringe Menge des Tensids notwendig. Auf polaren Masken oder Oberflächen ist Tween 20 entbehrlich, stört aber nicht. Der Eigengeruch von Tween 20 nach Braten stört etwas, weshalb es möglichst zu maximal 1% eingesetzt werden soll.
4. 4. Eine hochsiedende, möglichst hygroskopische Flüssigkeit: Dazu gehören vor allem Glycerin aber auch Propandiol, PEG. Diese Flüssigkeiten verdunsten kaum und garantieren die dauerhafte Haftung der Salzkristalle auf der Maske oder Filter. Auch fangen diese Flüssigkeiten frei fliegende Viren unelastisch ab. Die hygroskopischen Flüssigkeiten garantiert auch die schnelle Aufnahme von Wasser über einen großen Bereich der relativen Luftfeuchtigkeit. Allerdings darf der Flüssigkeitsfilm nur hauchdünn sein, damit die Salze und die Viren zusammen kommen können.
5. 5. Das Rezept für die Imprägnierung richtet sich nach dem verwendeten saugfähigen Material. Feinfasriges Material hat eine größere Aufnahmekapazität für Flüssigkeiten als aus unpolare Material bestehende Stoffe. So ist es wichtig die Salzlast an diese Oberfläche anzupassen. Vereinfacht kann von einer 4 fachen inneren Oberfläche ausgegangen werden.

When impregnating, four components that are harmless to health and the surface to be impregnated must be considered:

1. 1. Water is used to dissolve, dilute and evenly apply the components: For example, applying a saturated saline solution to the mask is not useful if it will make the mask too stiff and impermeable to air. In this case, the saline solution must be diluted with water or sprayed less
2. 2. Salt as antiviral component. The salts should be as soluble in water as possible, possibly hygroscopic, and their solubility should be strongly temperature-dependent. The selection of the salts depends on the place of use and the relative humidity prevailing there.
   1. a. Because of the high relative humidity of the breathing air that prevails there, salts with a high deliquescence moisture content can be used in mouth and nose protection masks: e.g. common salt.
   2. b. In room air filters with changing relative humidity, salt solutions must be used in which the crystallization and dissolution processes occur over the widest possible range of humidity.
3. 3. The tenside, eg Tween 20, must be used primarily for the impregnation of non-polar materials in order to ensure that the surface is wetted. Only a small amount of surfactant is required for this wetting. Tween 20 is unnecessary on polar masks or surfaces, but does not interfere. The inherent roasting smell of Tween 20 is somewhat disturbing, which is why it should be used at a maximum of 1%.
4. 4. A high-boiling liquid that is as hygroscopic as possible: This primarily includes glycerol, but also propanediol and PEG. These liquids hardly evaporate and guarantee the permanent adhesion of the salt crystals to the mask or filter. Also, these liquids catch unelas free-flying viruses table off. The hygroscopic liquids also guarantee the rapid absorption of water over a wide range of relative humidity. However, the liquid film must only be extremely thin so that the salts and the viruses can come together.
5. 5. The recipe for impregnation depends on the absorbent material used. Finely fibrous material has a greater absorption capacity for liquids than materials made of non-polar material. So it is important to adapt the salt load to this surface. In simplified terms, a 4-fold inner surface can be assumed.

6.1.4.1 Saline

• 1. In 1 L dist. Water, 300 g table salt and 20 g glycerin and, if necessary, a maximum of 10 g Tween 20 for non-polar masks are weighed out.
• 2. Be careful before adding the Tween 20, the glycerin must be completely dissolved, otherwise the Tween 20 will form a slow-dissolving gel with the glycerin. The solution is thoroughly shaken until all components are dissolved.
• 3. If necessary, filter a cloudy solution with a coffee filter to avoid clogging the sprayer nozzle.

6.1.4.2 Permanent impregnation solutions effective over a large range of humidity, e.g. for protective gloves and air filters:

6.1.4.3 Ammonium sulfate solution

1 part ammonium sulfate is dissolved in 3 parts water and 1 part glycerin is added. The water evaporates from this solution in the air, with the ammonium sulfate crystallizing out, up to a water content of 8%.

Ammonium sulphate is a main component of particulate matter in the air. This fine dust is formed from ammonia from agriculture and sulfuric acid. The latter is formed from sulfur dioxide when wood and coal are burned and oxidized to form sulfur trioxide and sulfuric acid.

This ammonium sulphate is one of the most important components in the formation of condensation nuclei during rain formation. Organic substances in the air envelop the ammonium sulphate crystal with the condensed water and ensure its stability against drying out.

6.1.5 Impregnation equipment

The spray bottles used in households in the bathroom, kitchen and for windows have proven to be particularly effective as a spray bottle for impregnation, as the nozzles in the spray heads clog so easily.

Fill the spray bottle with lukewarm water and use it to rinse the nozzle head

6.1.6 Impregnation

6.1.6.1 Salt layer

Approximately the same amount of impregnation solution is required per kg of fabric to completely soak the fabric. If a saturated salt solution is used, then there would be around 300 g of salt per 1 kg of fabric! This forms an invisible, wafer-thin layer of approx. 10-40 µm of salt crystals.

These salt crystals and the tissue are covered by around 1000 layers of the surfactant Tween 20 - with a total thickness of 2 µm.

6.1.6.1.1 Spraying

If you want to limit the amount of salt on the surface, use a diluted salt solution instead of a saturated one. This is especially true for respirators.

This method has the advantage that the impregnation can be well limited and not too large amounts of salt get on the surface, so that clogging of a mask, for example, is avoided.

To get a defined salt load on the mask, you can also proceed as follows: Weigh the mask and/or the spray bottle before and after spraying with water. In this way, the amount of liquid necessary for thorough moistening is obtained. After the mask has dried, spray it with approximately the same amount of diluted waterproofing solution.

6.1.6.1.2 Dipping and wringing

By immersing the fabric in the impregnation solution, a faster and more thorough impregnation is achieved compared to spraying. Then wring out the fabric to minimize the salt impregnation. It is therefore advisable to use a diluted salt solution of 30 g salt / 100 g water from the outset when dipping and wringing out fabrics! However, the salt coating cannot be controlled as well with this method as with spraying.

6. 1.6.2 Drying of the impregnated fabrics

Air drying takes time, but no energy expenditure.

Drying with a hot air device, e.g. a hair dryer, is quicker - but more energy-consuming.

When drying in a microwave, it should be noted that no metal, such as the sewn-in metal band on the mask, may be placed in the microwave, otherwise sparks and fire may occur.

Depending on the material, drying takes place in the oven at a temperature of up to 80 °C.

6.1.6.3 Prevention of skin irritation from salts

All salts can cause skin irritation in concentrated form. It is therefore beneficial to place a non-polar material, e.g. from a filter mask made of polypropene (PP) or polyethene (PE), between the material impregnated with the salt solution (usually cotton) and the skin, which due to its non-polarity prevents the salt from migrating in the direction of the skin and thus prevents direct contact of the salt with the skin.

6.1.6.4 Re-wetting

If, for example, impregnated gloves are dry, they can simply be moistened by spraying with as little water as possible and thus reactivated against viruses. If hygroscopic or high-boiling liquids or hygroscopic salts were used for impregnation, then there is no need for re-wetting. To be on the safe side, however, the moisture content should be checked with test paper. However, high-boiling liquids also evaporate constantly, so that the salt dissolved in them must inevitably crystallize out. In the case of glycerine, however, this evaporation takes weeks, whereas it occurs much faster when using propanediol-1,2.

6.1.7 Places of Application

6.9.7.1 Surfaces

6.1.7.1.1 Water absorbing (hydrophilic) surfaces:

The tenside (e.g. Tween 20) can be omitted for cotton or other water-loving surfaces. However, the adhesion of the salt crystals is then less, but this is improved again by adding glycerin.

6.1.7.1.2 Laboratory furniture

If you want to remove viruses from the surfaces of laboratory furniture, it makes sense to only spray them with a saturated salt solution.

If a saturated aqueous salt solution is sprayed on, it deactivates the viruses on the surface. After drying, the salt can simply be vacuumed off or wiped off.

6.1.7.1.3 Floor treatment

Test spray a small area first to see if discolouration occurs, which is not expected. Then spray the surface with an impregnation solution, the salt mixture of which is adapted to the relative humidity. If the salt solution dries out, it can be reactivated at any time by spraying with a little water.

See Fig. 4 surface treatment with a salt solution

Carpet and other floors only need to be sprayed with a saturated aqueous saline solution. After drying, the salt can be vacuumed off along with the dead viruses.

6.1.7.1.4 Impregnation with hygroscopic substances.

If you want to achieve long-term impregnation of surfaces, you cannot do without hygroscopic and/or high-boiling liquids in a dry environment. Basically, the antiviral effect comes from the dissolved salt and its transition to the solid state. The moisture for the saline solution can either be present in the mask or carried in with the viruses via the respiratory droplets. If the salt is constantly present in a concentrated solution due to hygroscopic or high-boiling components, this has an antiviral effect simply by denaturing the proteins.

6.1.7.1.4.1 Mask: Saline impregnation + Tween 20

Impregnating solution: 30 g NaCl + only for plastic masks less than 1 mL Tween 20 + 2 mL glycerin in 100 mL dist. dissolve water. Spray on the mask or dip and wring it out: The cotton mask absorbs up to two volumes of liquid. It initially contains about 0.5g of salt per 1g of mask. After about 3 weeks the salt content is constant at 0.35 g NaCl per g fabric or approx. 35% salt/mask. The surfactant Tween 20 is only necessary for masks made of non-polar plastic (PP and PE) and should be omitted for cotton masks. The glycerin makes the mask more supple and skin-friendly and ensures better adhesion of the salt crystals. In principle, glycerin and Tween 20 can be varied within a wide range of amounts and even omitted entirely. Other salts can also be used instead of sodium chloride. The following salts are suitable for the treatment of masks and room air - without health restrictions. These salts show blooming = crystallization and deliquescence over a wide range of relative humidity (relative humidity range is in parentheses): sodium acetate (20-100%),
sodium malonate (0-90%),
Sodium Tartrate, Ammonium Tartrate, (0-100%),
Ammonium sulphate + glycerin 1:1 (0 -77%).
Magnesium chloride (33-100%) forms multiple solvates ⁵⁰ .

Magnesium and calcium nitrate (0-100%), disodium maleate, disodium succinate are not suitable for protective masks for health reasons, but are suitable for room air filters.

Layer thickness of table salt on the fabric mask

• 10g Natriumchlorid (in Lösung) wurde auf 20 g der doppellagigen Maske mit einer beidseitigen Oberfläche von 720 cm² (18 cm * 10 cm *2 Lagen* 2 Vorder- und Rückseite) aufgetragen.
• 10g Salz sind auf 720 cm² Stoffoberfläche. Daraus errechnet sich eine Dicke der Salzschicht von 50 µm
• Nach drei Wochen Maskenbenutzung sind es immer noch 35 µm Salzschicht, diese ist von einer 1 µm dicken Tween 20-Schicht umhüllt.

Example of an impregnation:

• 10 g of sodium chloride (in solution) was applied to 20 g of the double-layer mask with a surface area of 720 cm ² on both sides (18 cm * 10 cm * 2 layers * 2 front and back).
• 10g salt is on 720 cm ² fabric surface. From this, a thickness of the salt layer of 50 µm is calculated
• After three weeks of mask use, there is still a 35 µm salt layer, which is covered by a 1 µm thick Tween 20 layer.

6.1.7.1.4.2 Gloves: impregnation with saline solution + Tween 20 + glycerin

Cotton gloves impregnated with glycerin feel cool and permanently damp, but not uncomfortable.

A liter of glycerin only dissolves 105 g of table salt. In comparison, 1 liter of water dissolves more than three times the amount. Therefore, when preparing the gloves, it makes sense to dissolve the salt in the water and then add the glycerin and, in the case of gloves made of polypropylene (PP) (instead of cotton), it is essential to add < 1% Tween 20.

Recipe: 20 g sodium chloride + 1 mL Tween 20 in 100 mL dist. Dissolve water and stir in 20 mL glycerin. Spray or dip gloves in this and wring. Dry the damp gloves.

Multi-layer protective gloves are advantageous, the outer surfaces of which consist of a water-absorbing layer and can therefore be easily impregnated with saline solution.

Three-layer protective gloves are ideal, the inner layer absorbs sweat and the middle layer is the barrier layer against chemicals and microorganisms, and the outer layer, which is also absorbent, can be treated with an antiviral salt solution. See also 5 Impregnable protective gloves

6.1.7.1.4.3 Lab coat: Slightly hygroscopic impregnation with saline solution + surfactant + glycerin

Impregnation can be carried out in the same way as gloves. However, the amount of salt and glycerin could be reduced.

6.1.7.2 Room air

6.1.8 Virus filtration (vacuum cleaner, air conditioner, humidifier, indoor air purification and supply)

See Fig. 6 room air treatment against viruses

6.1.8.1 Dry filter (e.g. vacuum cleaner)

With dry filters, it is only possible to intercept the viruses with pores just below the virus size. These tiny pores cause a large drop in pressure and thus a high energy requirement. Also, they are easily clogged by larger particles such as airborne dust. This can be avoided by using multi-stage filters from coarse to fine.

Nevertheless, the filter effect of wet filters is far more effective.

6.1.8.2 Wet filter

The wet filter consists of a polar material on the inside that is coated on the outside with a non-polar material. See 6 Indoor air treatment against viruses

Surfactants must not be used, otherwise the salt impregnation of the internal filter will migrate to the non-polar part and then completely.

The impregnation of the filter with a high-boiling polar liquid guarantees that viruses and other microorganisms stick to the filter. Therefore, it is not necessary that the pore size of this filter is smaller than that of the virus or bacteria, since any unavoidable contact of the microorganism with the wet filter wall will inevitably fix the virus.

A function of the filtering - to mechanically destroy the virus through alternating crystallization and dissolution processes - can be checked, if necessary, by measuring the conductivity in the wet filter.

If the relative humidity is permanently high - where crystallization of the salt may no longer take place - a heater can, if necessary, force a crystallization process in the filter.

6.1.8.2.1.1 Filter with intermittent water addition

With this type of filter, the filter undergoes salt dissolution with subsequent salt crystallization by alternating the addition of water and subsequent drying. During this crystallization, the viruses are crushed.

See Figure 7 Controlled humidification of an impregnated filter

To prevent the viruses from being released again during drying or slipping through the dry filter, it is preferable to additionally impregnate the filter with a high-boiling polar liquid.

The suitable liquids are water, glycerin, polyethylene glycol (PEG, macrogol), 1,2-propanediol.

Salts with the highest possible osmotic pressure in a saturated solution can be used.

These include the salts listed in Table 1 on page 10.

The salts in Table 2 on page 12 pose no danger to humans if the filter breaks through.

The deliquescence of salts can also be used in the same way: the salts in table 3 on page 14 and better the salts in table 4 on page 15.

With this type of filter, the residual moisture, the crystallization processes and the addition of water must be monitored and controlled, e.g. by continuously measuring the conductivity of the salt-liquid mixture in the filter.

6.1.8.2.1.2 Filter impregnated with a high-boiling liquid and deliquescent salt.

It is easier to use a salt mixture in which salt dissolution and/or virus-destroying crystallization takes place over the widest possible range of relative humidity, if this changes slightly. These include the salts mentioned under point 6.1.3.5.

The possible salts are also listed in Table 3 on page 14.

Table 4 on page 15 lists deliquescent salts without restrictions on hazardous substances.

Selection of deliquescent salts suitable for air purification through for air filters, for water mist and for protective masks that interact less with each other

Sulphates group: Table 9 on page 17: Potassium sulphate, sodium sulphate, magnesium sulphate, urea, potassium formate, ammonium sulphate: Effective range depending on the mixture relative humidity 96.4% to well below 40%)

Chloride group: Table 8 on page 17: Sodium chloride, potassium chloride, urea, potassium formate, magnesium chloride hexahydrate: Effective range in the relative humidity from 84% to below 33%

Potassium salts group: Table 6 on page 16

Group of ammonium salts: Table 7 on page 16

Magnesium sulfate (M _{gSO 4} *H ₂ O to MgSO ₄ *11H ₂ O).

Some salts have several hydrate contents and recrystallize to a more hydrated level with increasing relative humidity with an increase in volume. Virus crushing also occurs here, although not to the extreme extent of recrystallization. These salts include magnesium sulphate with a crystal water content of 1 to 11 ^%

6.1.8.2.2 Air conditioning

The filter of an air conditioner must never be allowed to dry out, otherwise its antiviral impregnation is ineffective. In order to prevent this drying out, the filter should be impregnated with either a high-boiling liquid or a hygroscopic component of salt and/or surfactant and/or solvent.

A second way is to control the humidity of the filter with a targeted addition of water when it dries up.

The easiest way is a constant low supply of moisture, which must be based on the humidity, however, so that the filter does not get too wet or too dry. See also 7 Controlled humidification of an impregnated filter

6.1.8.2.3 Room humidifier

These devices have the advantage that they constantly release water. In this case it is only necessary to impregnate the filter with a salt solution and surfactant.

6.1.8.2.4 Fan

A workaround is to hang a cloth impregnated with salt and a high-boiling liquid in front of the fan. When the salt layer dries up, spraying with water is sufficient. The high-boiling liquid acts as a virus scavenger and the salt destroys the viruses when it crystallizes out.

6.1.8.2.5 vacuum cleaner

Dry vacuum cleaners are virus spinners.

Vacuum cleaners do not protect against viruses. On the contrary, they still distribute them in the room because the tiny viruses can penetrate unhindered through the relatively large pores of the filters. Vacuum cleaners with water are better. These greatly reduce the virus load.

If you want to reduce the virus load with a normal vacuum cleaner, it is worth spraying the carpet or floor with a concentrated saline solution (300 g of saline per 1 liter), allowing it to dry and then vacuuming up the salt together with the deactivated viruses. See point: 9.1.3.

6.1.8.2.5.1 Dry vacuum cleaner

With these vacuum cleaners, you can help yourself by impregnating the outside of the vacuum cleaner bag with a high-boiling and/or hygroscopic salt solution.

See 5 Surface treatment with a saline solution.

Impregnating the outside of the vacuum cleaner bag with a solution of Tween 20, table salt and water is more pleasant but more complex. This moistening of the vacuum cleaner bag must always be repeated.

6.1.8.2.5.2 Bag vacuum cleaner

Impregnation of a vacuum cleaner bag: see 5 Surface treatment with a saline solution

Subsequent impregnation of the inside of the vacuum cleaner bag with an aqueous solution of salt and surfactant is less optimal, since the virus is primarily destroyed by recrystallization of the common salt. With an existing vacuum cleaner, you could help yourself by sucking in some water from time to time during the suction process. However, this is not recommended, since the motor is water-protected against this mishandling, but metering the amount of liquid is difficult and the entire contents of the dust bag would first be soaked until the water for impregnation comes. It is better to use hygroscopic substances in the impregnation solution. At least one component of the impregnation solution must be hygroscopic or high-boiling: Use a hygroscopic and non-hygroscopic salt together with a surfactant that is as hygroscopic as possible and a mixture of a liquid made of high-boiling, hygroscopic liquid and some water to impregnate the vacuum cleaner bag from the outside. Even if crystallization does not necessarily take place, a saturated salt solution has a denaturing effect on the proteins of the viruses. It is optimal if, in addition, a virus crushing takes place with only slight temperature changes due to constant crystallization and dissolution processes of the salts.

A controlled, intermittent water supply for moisturizing would be ideal.

6.1.8.2.5.3 For all vacuum cleaners with a ducted air outlet

6.1.8.2.5.4 Water vacuum cleaner

Water vacuum cleaners have the advantage that the exhaust air filter can be impregnated with a hygroscopic salt solution without major conversion work. As a temporary solution, it is enough to put salt in the water tank of the water vacuum cleaner.

Vacuum cleaner with water filter

Vacuum cleaners with a water filter should catch viruses relatively well. However, it is also worth equipping them with an antiviral impregnation. Only the filter at the air outlet can be used for this antiviral impregnation. The advantage here is that the air is saturated with water.

This means that the water condenses here and also evaporates again and the virus is destroyed by dissolving and recrystallizing the salt. The saturated salt solution has a denaturing effect on the proteins of the viruses.

The constant supply of water-saturated air prevents this wet coating from drying out completely.

However, if this moistening is not sufficient, then a weakly hygroscopic salt and/or a hygroscopic surfactant and/or a water-miscible solvent with the highest possible boiling point should be used. As a result, the virus would be destroyed by the high osmotic pressure and the tenside would have a bactericidal effect. Polyethylene glycols have proven to be favorable.

These polyethylene glycols hardly evaporate and are also hygroscopic.

Vacuum cleaner without water filter

Vacuum cleaners without a water filter could be equipped with an antiviral filter at their outlet.

Since the air heated by the vacuum cleaner motor does not carry any condensed water with it, you have to manage as follows: See 8th Schematic drawing of a converted dry vacuum cleaner that can no longer act as a virus slingshot.

6.1.8.3 Methods of generating liquid droplets

6.1.8.3.1 thermal atomization (nebulizer) e.g. by fog machines

With fog machines, large rooms can be washed out of viruses very effectively and clearly visible with liquid droplets.

The advantage is that the liquid is sterilized during thermal atomization under pressure and heat.

Added high-boiling liquids extend the service life of the mist.

Salts cannot be used with thermal atomization because they would clog the fog machine by crystallizing out. Thus, no mechanical destruction of the virus by crystallization of the salts is possible.

This disadvantage can be compensated for by adding non-ionic, vaporizable surfactants such as 1% Tween 20 (Polysorb 20), which deactivate viruses. However, their smell of roasting is not particularly attractive.

6.1.8.3.2 mechanical atomization

The mechanical atomization of liquid droplets takes place using a pump (nozzle) or ultrasound or a rotating disc, i.e. without heat. It is therefore necessary to sterilize the nebulized liquid. The sterilization takes place via an extremely high salt concentration and the addition of surfactants.

The washing liquids mentioned above are used.

6.1.8.3.2.1 Salts with high osmotic pressure

The salts listed in Table 1 with a high osmotic pressure of the saturated solution could be suitable as salts. Taking into account the Ordinance on Hazardous Substances, this list is reduced to the salts in Table 2 on page 12.

6.1.8.3.2.2 Hygroscopic and/or deliquescent salts

• Diese Salze sind in Tabelle 3 aufgeführt. Auch hier wieder muss die Gefahrstoffverordnung berücksichtigt werden, so dass sich die geeigneten Salze in Tabelle 4 wiederfinden.
• Diese Salze wirken auch, nachdem sie auf der Arbeitsoberfläche oder dem Boden gelandet und bei gegebener Luftfeuchtigkeit auskristallisiert sind, bei sich ändernder Luftfeuchtigkeit oder Temperatur durch Schmelzen im eigenen Kristallwasser und wieder Auskristallisieren antiviral. Dabei deckt die Mischung der Salze einen weiten Bereich der Luftfeuchtigkeit ab. Die Sulfatsalze decken je nach Mischungsverhältnis der Einzelkomponenten einen Bereich der relativen Luftfeuchtigkeit von 96,4% bis weit unter 40 % ab.
• Die Chloridsalze decken je nach Mischungsverhältnis der Einzelkomponenten einen Bereich der relativen Luftfeuchtigkeit von 84% bis weit unter 33 % ab.
• Dabei ist zu beachten, dass die Salzmischungen zumeist niedrigere Gleichgewichtsfeuchten⁵² als die Reinkomponenten haben.
• Die Berechnung der Gleichgewichtsfeuchte für das Schmelzen der Salze in ihrem Kristallwasser (relative humidity of deliquescence) für Salze und Salzmischungen kann gemäß
• S. Metzger and J. Lelieveld ⁵³ durchgeführt werden.

If the atomized salt water droplets are to remain in the air for longer, then hygroscopic additives are ideal:

• Table 3 lists these salts. Here again, the Ordinance on Hazardous Substances must be taken into account, so that the suitable salts can be found in Table 4.
• These salts also have an antiviral effect after they have landed on the work surface or the floor and have crystallized at the given humidity level, by melting in their own crystal water and crystallizing out again when the humidity level or temperature changes. The mixture of salts covers a wide range of humidity. Depending on the mixing ratio of the individual components, the sulphate salts cover a range of relative humidity from 96.4% to well below 40%.
• Depending on the mixing ratio of the individual components, the chloride salts cover a range of relative humidity from 84% to well below 33%.
• It should be noted that the salt mixtures usually have lower equilibrium moisture levels ⁵² than the pure components.
• The calculation of the equilibrium moisture for the melting of the salts in their crystal water (relative humidity of deliquescence) for salts and salt mixtures can be done according to
• S. Metzger and J. Lelieveld ⁵³ .

6.1.8.3.2.3 with liquid + salt + surfactant

A surfactant increases effectiveness and better fixes both viruses and salt to surfaces. Only neutral surfactants such as Tween 20 are suitable as surfactants.

reference list

• 1 Viruses in water droplets in the air we breathe are released after they have evaporated. They then move quickly at around 10 cm/s and can easily penetrate dry cloth masks. That is why respiratory masks are better virus scavengers.
• 2a Successful virus attack on human cell

  1

  virus

  2

  Protein of the virus as an anchor to the human cell

  3

  human cell

  4

  Glycolipid on the surface of the human cell as a docking site for the surface proteins of the virus

  5

  Successful docking of the virus and infusion of the virus RNA into the human cell

• 2 B : Virus destruction with salt and water

  6

  Virus in water droplet (aerosol)

  7

  the water droplet with virus hits salt and dissolves it.

  8th

  The dissolved salt leads to refolding of the virus protein.

  9

  The protein denatured on the surface of the virus can no longer dock onto the human cell

  10

  As the water evaporates, the crystallizing salt traps and crushes the viruses.

  11

  Decay of crushed and/or denatured virus.

• 3 : Impregnable protective glove

  12

  Two-layer glove

  13

  Three layer glove

  14

  Absorbent layer of fabric suitable for impregnation

  15

  A layer impervious to chemicals and/or microorganisms.

  16

  Inside a sweat-absorbent layer made of cotton, for example.

• 4 . Surface treatment with a salt solution (deliquescent and/or hygroscopic salt with water and/or high-boiling liquid such as glycerin)

  17

  Impregnation of floors and other surfaces with a saline solution that is reactivated by spraying with water.

  18

  Impregnating the outer bag of a vacuum cleaner to bind and deactivate viruses

  19

  Impregnating the inner bag of a vacuum cleaner to bind and deactivate viruses

  20

  Impregnation of a cloth, which is hung in front of the circulating air device or the fan, with a permanently moist salt solution - eg with glycerin

• 5 Indoor air treatment against viruses

  21

  Modified sprinkler or water spray system with nozzle made of a non-polar material, which is less likely to clog with salt crystallization, for spraying salt water solution (ERH > RH). The saline droplets wash out and inactivate viruses

  22

  Atomizer of the finest salt powder that is invisibly suspended in the air to deactivate viruses in respiratory droplets by mechanically crushing the salt when it crystallizes out. Has low efficacy on dry viruses unless a hygroscopic salt is used at relative humidity (DR) (deliquescent relative humidity DRH<RH).

  23

  Fog machine suitable for vaporizing and spraying high-boiling polar liquids. This liquid causes the viruses to be washed out and fixed on the floor and other surfaces. Possibly combined with salt spray (e.g. sodium chloride with magnesium chloride = sea spray).

  24

  Mechanical atomizer (by suction or by pressure or by rotating disc) for dispensing spray solution of high-boiling liquid such as glycerol and ammonium sulphate or water and various salts such as magnesium chloride, disodium malonate, etc.

  25

  Three-layer wet filter for capturing viruses from circulating air

  26

  The outer layers are made of non-polar filter material that fits tightly to the inner layer.

  27

  The internal filter made of polar material is impregnated with a virus-deactivating impregnation solution made from a high-boiling solution such as glycerol and ammonium sulfate in a mass ratio of 1:1. The intimate contact with the two non-polar outer filters prevents the salt solutions from migrating and blooming.

  28

  Filter holder that ensures intimate contact between polar and non-polar filters.

• 6 Schematic drawing of a converted dry vacuum cleaner that can no longer act as a virus slingshot.

  29

  vacuum cleaner pipe

  30

  anthers

  31

  engine with fan

  32

  Pulsed humidification unit controlled by the moisture meter

  33

  water

  34

  Sponge impregnated with salt and surfactant on the air outlet

  35

  Moisture meter on the front and back of the sponge to control the moistening

• 7 Controlled humidification of an impregnated filter

  36

  supply air

  37

  humidifier fluid

  38

  eg valve controlled by an electromagnet

  39

  Controller for humidification

  40

  Moisture meter eg via the conductivity

  41

  Filter made of polar material impregnated with salt and coated with non-polar filter material.

  42

  Virus-free air

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102016002826 A1 [0005, 0009]
• WO 97/25415 [0006]
• DE 2842091 A1 [0008]
• EP 000000357693 B1 [0010, 0014]
• DE 19808192 A1 [0011, 0016]
• DE 000019808192 A1 [0012]
• DE 3886332 T2 [0013]
• DE 3528209 C2 [0015]
• EP 1053754 A1 [0017]
• DE 19923027 C2 [0018]
• WO 9725415 [0059]

Claims (8)

The impregnation of surfaces with an antiviral solution is characterized by the fact that the surfaces of the air filters of air conditioning systems, circulating air devices and room air humidifiers, the exhaust air filters of vacuum cleaners, the floors, in short all surfaces in hospitals, laboratories, factories, public buildings and sprayed or coated in the home with an invisible, wafer-thin layer of a saturated salt solution consisting of water, salts, a high-boiling liquid such as glycerine and a surfactant such as Tween 20. The separation and rendering harmless of viruses and other microorganisms from the room air is done effectively with in claim 1 mentioned, saturated salt solution by mechanical and not with thermal nebulizers. This impregnation according to claims 1 and 2 works over longer periods of time thanks to the high-boiling and hygroscopic components. The salts and salt mixtures in the impregnation solution according to the Claims 1 until 3 Microorganisms have a draining effect via their osmotic pressure and virus proteins have a denaturing effect and/or denaturing via the chaotropic, i.e. "structure-breaking" effect, but also mechanically destroy the viruses with the smallest changes in room air temperature and humidity by crystallizing and dissolving them again (efflorescence and deliquescence processes). Are favorable according to the Claims 1 until 4 hygroscopic salts and salt mixtures, which have a deliquescent and efflorescent effect at different humidity levels and thus cover a wide range of indoor air conditions. The virus and other microorganism-destroying effect in the crystallization of salts on surfaces according to the claims 1 until 5 can be reactivated as often as you like by adding a little water after the salt solution has dried. Depending on the dryness, this water is added either manually or intermittently electronically. A desired control of the complete impregnation of surfaces such as masks and gloves according to the claims 1 until 6 is done by adding a color to the impregnation solution, which makes the impregnated surface with deactivated viruses clearly recognizable from the unimpregnated surface by changing the colour. In order for the skin to be protected by the salts of the surfactant-free impregnation solution in accordance with the claims 1 until 7 in the breathing masks and protective gloves may not be irritated, breathing masks or protective gloves can be made in two layers, with a non-polar mask material made of e.g. polypropylene or polyethene towards the skin on the inside and an absorbent material (e.g. made of cotton) on the outside for impregnation.

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