RU2810602C2 - Disinfecting paste and method for disinfecting substrate made from solid material using specified paste - Google Patents

Abstract

FIELD: disinfection.

SUBSTANCE: group of inventions relates to a paste for disinfecting substrates made from contaminated solid materials and a method for disinfecting contaminated substrates. A disinfecting paste is proposed containing: from 20 to 70 wt.%, based on the total weight of the paste, of at least one inorganic thickener selected from clays, wherein said inorganic thickener is in the form of particles of micron and/or nanoscale size; at least one compound in the form of fibres and a solvent - the rest. A method for disinfecting a substrate made of solid material is also proposed, including: applying the specified paste to the surface of the substrate; keeping the paste on the surface for a certain time; and removal of dry and solid residue containing contaminating particles.

EFFECT: invention allows disinfection of all types of materials, and also provides better internal cohesion of the paste without changing its advantageous properties of disinfection and drying, in particular, the paste can be held on a vertical wall without sagging, and after drying, solid, non-powdery waste is always formed.

23 cl, 3 dwg, 1 tbl, 4 ex

Description

TECHNICAL FIELD

The subject of the present invention is a disinfectant paste for disinfecting substrates of contaminated solid materials.

The present invention is also directed to a disinfection method using this disinfection paste.

Disinfection or cleaning of the substrate refers to the removal of polluting and contaminating substances from the substrate.

Contaminating substances generally refer to substances that are not a normal constituent of the substrate material and whose presence is undesirable.

Infecting substances can be on the surface of the substrate, directly below the surface of the substrate (in the subsurface layer) or deep in the substrate.

The method and paste according to the invention allow the disinfection of all types of materials, such as metal, plastic, mineral materials, such as glass materials.

The method and paste corresponding to the invention are equally applicable for the disinfection of both substrates made of dense material and substrates made of porous material, such as mineral binder material, for example, cement mortar, concrete; bricks; plaster; and natural stone.

The method and paste according to the invention also allow the removal of all types of contaminants, especially chemical, biological or radioactive contaminants.

Therefore, the method and paste corresponding to the invention can be, in particular, called a method and paste for NRBC (Nuclear, Radiological, Biological, Chemical) disinfection.

Thus, the field of technology to which the invention relates can generally be defined as the disinfection of contaminated substrates with the aim of removing contaminants, contaminating substances, contaminating particles that are located on their surface, directly below the surface (in the subsurface layer) or in the depth of the substrate.

BACKGROUND OF THE ART

Decontamination or cleaning of solid materials is a problem encountered in many areas, especially in the nuclear industry, for example for sanitization or maintenance of facilities, in some industries where toxic chemical products are used, but also, for example, in the context of decontamination operations which may be required following an NRBC type incident.

Various types of contamination of solid material can be mentioned:

- unstable contamination, in particular in the form of dust that does not adhere to the surface subject to contamination.

- so-called “surface contamination”: there are contaminating substances adhering to the surface of a substrate made of solid material (for example, in a lubricant layer).

- so-called “subsurface contamination”: contaminating substances are included in a layer several microns thick at the very surface of a solid substrate (for example, in a layer of metal oxide).

- deep contamination, characteristic of substrates made of porous materials. The infectious substances diffused into the pore network and were incorporated into the material at a depth of several millimeters or even centimeters.

As part of the decontamination operations, the method used usually takes into account the type of contamination present and the outlets for the final waste generated.

Thus, unstable infestation can be removed by methods involving simple absorption of the infestation. Non-persistent contamination can also be removed by applying a peelable gel to the surface to be disinfected, which acts as an adhesive tape and removes the unstable contamination from the substrate [1].

Peel-off gels are organic and are only effective against non-persistent infestations. As a result, they form organic waste. In addition, their application in a layer that is too thick (for example, more than 2 mm) can lead to runoff, which impairs the mechanical properties of the resulting peeling film.

There are various ways to influence surface and subsurface contamination:

- mechanical methods based on cutting, physical abrasion, sandblasting, scraping, leveling. Although these methods are inexpensive and relatively easy to implement, they are labor intensive for operators, damage the structure of the material, and produce large amounts of waste.

- chemical methods using acidic, basic or oxidizing solutions. Such methods are based on the corrosion of a material to a few microns in order to extract contaminating substances from it. Consequently, the material is slightly destroyed, and its disinfection is carried out only to a small depth. In addition, liquid waste is generated, which then needs to be treated or disposed of. Acidic, basic or oxidizing solutions can also be introduced into disinfection gels [2] or foams [3] to increase their effectiveness and reduce the volume of secondary waste generated.

In methods involving the use of foam, liquid effluent is generated in small quantities.

In methods involving the use of gel, solid waste is generated which can be sucked out provided that its application by spraying is precisely controlled. Indeed, in these methods it is important to regulate the thickness of the deposited gel in order to prevent the formation of waste that is too thin and too well adhered to the substrate (in the case of applying a too thin gel layer) or sagging on non-horizontal surfaces (in the case of applying a too thick gel layer).

Gels do not allow processing of porous materials and generally do not adequately isolate contaminating particles.

Finally, chemical methods are effective mainly for surface and subsurface disinfection and are not effective enough to remove contaminating substances deeply penetrated into the substrate.

- methods based on laser ablation [4]. This type of method consists of eroding successive layers of contaminated material using a laser beam in combination with a suction system to remove the resulting waste. However, such “laser” methods are quite expensive and have limitations in application.

Deep disinfection of porous materials is much more difficult than removal of transient, surface or subsurface contamination, since contaminants can penetrate deeply into the pore network.

Be that as it may, the methods of surface and subsurface disinfection described above can still be used for deep disinfection, but, on the one hand, their effectiveness is limited and, on the other hand, they generate a very large amount of secondary waste, which can present difficulties in handling, especially in the case of radioactive disinfection.

However, there are special methods for deep disinfection of porous materials.

First of all, these are electrokinetic methods [5], which are based on the electromigration of ion contamination in a porous material, in particular in reinforced concrete, when applying electrodes and applying current. These methods are characterized by high technological costs and require significant resources for their implementation. In addition, the application of high current may cause destruction of the infrastructure during processing.

In addition, the document [6] describes a method for disinfecting porous materials deeply contaminated with radionuclides. The described method is aimed at ion radioactive contamination, and there is no indication of the possibility of modification for use in areas other than the nuclear industry. This document outlines a two-step method. In the first stage, the porous material is impregnated with an ionic solution that can dissolve radionuclides present in the pores. At the first stage, influxes and liquid effluents may form, which present difficulties in terms of drainage and treatment. In addition, in the case of areas with complex geometries or large surface areas, such as walls, the porous material may be impregnated inhomogeneously, which reduces the effectiveness of the method. After the impregnation step, an organic hydrogel containing radionuclide chelating agents is brought into contact with the impregnated porous material to extract dissolved contaminants.

Document [6] only mentions organic gelling agents, which may be sensitive to radiation, especially in the specific case of radioactive disinfection, and emit radiolysis gases (in particular, H ₂ ).

This problem may not be acceptable when packaging final waste.

The claims of this document are directed to the dry composition before mixing with an aqueous solution, but information about the composition of the hydrogel and, in particular, the influence of the amount of aqueous solution to be added, is missing. In addition, there is no explicit indication of the method of application and use of the hydrogel. In particular, the document does not describe the influence of the thickness of the applied hydrogel layer, the means of applying the hydrogel, or the amount of hydrogel required to treat a given surface.

Reference [7] describes a dry compress, pad composition used for cleaning or desalting porous materials, more specifically for the treatment of contaminated stones in the context of monument restoration.

This dry composition includes a binder, filler and mineral fibers. Due to the very limited intended use, namely desalting and cleaning of historical monuments, it must meet highly specialized requirements (mainly safety criteria), giving rise to rather complex dry compress compositions of at least 3 components.

This document also relates to a cleansing or desalting compress, ready for use, which includes a dry composition, from 50% to 80% by weight. solvent and possibly a solubilizing agent.

The compress is applied to the surface to be treated.

The compress is then allowed to dry and the salts dissolved in the solvent that has penetrated the material to be treated are extracted by migrating into the compress. After drying, the remaining compress is removed during final rinsing, obtaining liquid effluent, and simultaneous suction.

The efficiency of cleaning and/or desalting achieved using the document compress [7] has not been confirmed, in particular, by examples of practical implementation and is probably low. Generally speaking, the use of compress is still strictly limited to desalting stones in the context of monument restoration.

In addition, it should be noted that processing vertical walls poses special problems. For example, to treat a vertical wall over a large area with a gel or compress, a significant layer thickness is sometimes required, allowing for high disinfection efficiency with non-powder waste (for example, in the case of disinfection of dense substrates with gels) or allowing the disinfection of a vertical porous surface through extraction mechanisms based on such physical phenomena such as fluid transport or advection. However, the composition of gels and compresses, described, respectively, in documents [2] and [7], does not allow these gels and compresses to “stick” to a vertical wall, to adhere to the wall without sagging, dripping, when they are applied to a vertical wall in a layer of significant thickness, in particular centimeter thickness.

The maximum thickness of a layer of gels and compresses that can be applied without sagging is several millimeters.

In view of the above, there is a need for a disinfecting composition, product and method of disinfection that would be devoid of the disadvantages, defects, limitations and inconveniences of methods, compositions and products for disinfection of the prior art, in particular, represented by the compositions and methods described in the documents [ 1] - [7].

In particular, there is a need for a disinfectant composition, product and method of disinfection that provides the following improvements, particularly with respect to disinfection suction gels and methods of using such gels:

- improving the properties of final waste. Indeed, suction-removable gels typically do not adequately isolate contaminating particles, which only adsorb to the surface of the final waste and are mechanically captured by the dry gel flakes.

- improvement of final waste size. Indeed, suction gels used for surface or subsurface disinfection produce millimeter-sized, non-powdery waste. Therefore, it would be desirable to increase the size of the waste to prevent resuspension in air.

- improving the flexibility, reliability and reproducibility of the method. Indeed, the effectiveness of application methods for suction-removable gels largely depends on spray application, which must be well controlled. In some cases, improper application of the gel, particularly if the applied gel layer is too thin, leads to poor disinfection and the generation of solid waste that is too fine and adheres too much to the substrate. Waste that is too small and sticky is known to be difficult to remove. Therefore, it would be desirable to have a method that is easier to use, reliable, reproducible, accurate and more robust than known methods, and less sensitive to the risks that may arise during its use.

- in addition to methods of deep abrasive processing, currently there is no disinfecting composition or method for effective deep disinfection of the material. Therefore, it would be desirable to have a composition and method that would provide deep disinfection while generating a small volume of final waste.

Thus, at present there is no disinfectant composition or method that simultaneously provides disinfection of unstable, superficial, subsurface and deep contamination of solid materials. Therefore, there is a need for such a composition and such a method, which, in addition, would be inexpensive, reliable and easy to use, not associated with the formation of liquid waste, on the contrary, only solid waste of large size, namely, generally more than one centimeter.

In particular, there is a need for an effective composition and an effective method for deep disinfection of porous materials. These materials can have a large surface area.

DESCRIPTION OF THE INVENTION

This and some other goals in accordance with the invention are achieved by means of a disinfecting paste containing, preferably, consisting of:

- at least one inorganic thickener selected from clays, wherein said inorganic thickener is from 20% to 70% by weight, preferably from 35% to 70% by weight, more preferably from 40% to 65% by weight ., and preferably from 45% to 55% wt. the total weight of the paste, while the specified organic thickener is in the form of particles of micron and/or nano-scale size;

- at least one connection in the form of fibers;

optionally, in addition, one or more components selected from the following:

- at least one surfactant (surfactant);

- at least one active disinfecting agent;

- at least one particle-extracting agent;

- at least one chelating agent for infectious particles;

- at least one coloring agent;

the rest is solvent.

Advantageously, said component(s) are present in the following quantitative ratio:

- from 0.1 to 8 or 10% by weight, preferably from 0.1 to 5% by weight, more preferably from 0.5 to 5% by weight, better, from 1 to 5% by weight, even better , from 1 to 3% wt. relative to the weight of the paste of at least one fiber-shaped compound;

- optional, from 0.1 to 2% wt. relative to the weight of the paste of at least one surfactant;

- optionally from 0.1 to 10 mol/l paste, preferably from 0.5 to 10 mol/l paste, more preferably from 1 to 10 mol/l paste, better from 3 to 6 mol/l paste, at least one active disinfectant agent;

- optional, from 0.1% to 5% wt. relative to the weight of the paste of at least one particle-extracting agent;

- optional, from 0.1% to 5% wt. relative to the weight of the paste of at least one chelating agent;

- optionally from 0.01% to 10% by weight, preferably from 0.1% to 5% by weight. relative to the weight of the paste of at least one coloring agent;

- the rest is solvent.

The sum of the weight percentages of all components that make up the paste is naturally equal to 100% weight.

By the expression "the rest is solvent" it is meant that solvent is always present in the paste, and that the amount of solvent is such that when added to the amount of components of the paste other than solvent (whether the essential or optional components mentioned above, or other optional components mentioned above) or not mentioned), the total amount of all paste components is 100% by weight.

By micron size particles it is meant that the average particle size, generally defined by its largest dimension, is from greater than 0.1 μm to 100 μm, preferably from 1 to 100 μm, for example from greater than 0.1 µm, up to 4.5 or 10 µm.

Said inorganic thickener is preferably present only in the form of particles in the micron size range.

By nano-sized particles it is meant that the average particle size, usually defined by its largest dimension, is between 1 and 100 nm.

The paste according to the invention includes a certain amount of a certain clayey inorganic thickener giving the paste a viscosity adequate for its use, at least one fiber-shaped compound and a solution containing a solvent, and, optionally, one or more optional components, which are usually selected in according to the specific application of the paste.

The term "paste" is well known to those skilled in the art, who understand that it is different in nature from the gel formed by a colloidal solution.

The paste according to the invention generally has a viscosity greater than or equal to 100 Pa.s at 20° C. for a shear rate of less than 1 s ^-1 .

Depending on the component(s) it contains, the solution may react with or etch the substrate, dissolve or wash away contaminating particles, or fix contaminating particles during the decontamination stage (see below).

The disinfectant paste according to the invention has never been described or proposed in the prior art.

The disinfecting paste according to the invention differs fundamentally from the disinfecting compositions corresponding to the prior art, especially from the suction-removable gels of the prior art, in that the paste contains a special inorganic thickener selected from clays, and not from oxides of silicon and aluminum, and in that that the amount of inorganic thickener in the paste is greater than the amount of inorganic thickener in the suction-removable gels. Indeed, the amount of inorganic thickener in the paste is from 20% to 70% by weight, preferably from 40% to 65% by weight, even better from 45% to 55% by weight. The disinfectant paste according to the invention also differs fundamentally from prior art disinfectant compositions, particularly from prior art suction-removable gels, in that the paste contains at least one compound in the form of fibers.

In addition, the inorganic thickener is preferably present only in the form of particles in the micron size range.

The micron range of particle sizes contributes to the production of large-sized solid waste.

The paste corresponding to the invention meets all the above requirements, allows you to achieve all your goals and solve all the problems inherent in disinfecting compositions of the prior art.

Thus, the paste according to the invention unexpectedly makes it possible to simultaneously remove unstable contamination, superficial contamination, subsurface contamination and deep contamination (for example, contamination embedded in the pore network of a substrate made of a porous material).

Thanks to a special inorganic thickener selected from clays, a special large amount of inorganic thickener and, preferably, due to the presence of an inorganic thickener in a special form of particles in the micron size range, the paste according to the invention can, surprisingly, be held without running down or sagging on vertical walls, even if it is applied to the walls in a much thicker layer than the layer used to apply suction-removable gels. This thickness in particular ranges from 2 to 5 mm.

Since the paste according to the invention also contains a compound in the form of fibers, this thickness can be even greater than 5 mm.

Thanks to the large, significantly increased application thickness (compared to suction-removable gels) achieved with the paste according to the invention, the disinfection effect, in particular the corrosive effect, is enhanced, and deeper and subsurface disinfection becomes possible.

Despite the large, specific amount of inorganic thickener in the paste according to the invention, it nevertheless retains an easy-to-handle consistency, allowing it to be easily applied to any surface. In addition, the number of cracks that occur during drying of the paste according to the invention is significantly reduced compared to drying suction gels, while solid waste is formed, consisting of pieces, non-powdery particles and having a larger size than the waste obtained after drying suction gels .

The waste resulting from drying of the gel according to the invention generally has a size (the size being determined by the largest dimension) greater than or equal to one centimeter, or even greater than or equal to 10 cm. Often the final dry waste is small (for example, one , two) cracks or no cracks, therefore, the same size as the originally applied “wet” gel (see examples).

The use of clays eliminates the appearance of cracks, since they are better organized when dried.

In larger wastes, contaminating particles may be chemically adsorbed.

The presence in the paste according to the invention of a compound in the form of fibers, even in the above-mentioned small amount, provides better internal cohesion of the paste without changing its advantageous disinfecting and drying properties. Thus, the presence of the compound in the form of fibers ensures that even with a greater thickness of the paste layer, for example greater than or equal to 5 mm, preferably greater than or equal to 6, 7, 8 or 9 mm, more preferably at least 10 mm and up to 50 mm, the paste can be held on a vertical wall without sagging, and after drying it always produces solid, non-powdery waste. This is shown in example 4.

It should be noted that the paste does not need to contain one or more of the optional ingredients listed above.

Indeed, in the case of removing certain types of contaminating particles, a paste containing only a solvent, a thickener and a compound in the form of fibers can be successfully applied by the method according to the invention, providing capture and entrapment of contaminating particles and achieving the effects and advantages listed above. In this case, for these types of infectious clay particles, they act both as a thickener and as a “trap” and “fixer”.

However, other types of contaminants that are not captured by clay require optional components to capture them. Optional components may be particle-contaminating agents extracting agents and/or particle-contaminating chelating agents.

The presence of a surfactant in the paste according to the invention has a beneficial and significant effect on the rheological properties of the paste. In particular, the surfactant helps restore the viscosity of the paste after application and eliminates the risk of spreading or sagging when applying the paste to vertical surfaces and ceilings.

The presence of at least one active disinfecting agent in the paste makes it possible to remove, exclude, destroy, decontaminate, destroy, extract contaminating particles, be they particles of unstable, superficial, subsurface or deep contamination below the surface, below the surface of a solid substrate.

The presence in the paste of at least one extracting, retrieving and fixing agent, such as an inorganic adsorbent, facilitates the capture, removal and fixation of contaminating particles, and also prevents the release of contaminating particles in the event of possible leaching, in particular, unwanted leaching of final dry or solid waste. The treatment of waste generated during disinfection using the paste according to the invention is greatly facilitated.

As stated above, clays, in some cases, can act as both a thickener and a “trap” and “fixer.”

The presence of at least one particle chelating agent in the paste also facilitates the capture, fixation and removal of contamination particles.

In particular, the presence of contaminant-extracting and/or chelating agents in the paste, or more specifically in the solution forming part of the paste, accelerates the extraction of chemically bound contaminants from the pores of a material, such as a mineral binder.

The presence of at least one coloring agent in the paste improves the visualization and identification of the final dry solid residues at the end of the operation, regardless of the type of surface to which it is applied, thereby facilitating removal of the residues.

Due to the use of a generally exclusive inorganic mineral thickener and the absence of any organic thickener, the content of organic material in the paste according to the invention is generally less than 4% by weight, preferably less than 2% by weight, which is an advantage of the paste according to the invention .

Solid mineral inorganic clay particles act as a thickener to achieve the desired paste consistency.

Advantageously, the inorganic thickener may be selected from smectites, kaolinites, perlites, vermiculites and mixtures thereof.

Surprisingly, it turned out that the nature of the inorganic mineral thickener affects the drying of the paste according to the invention and the grain size of the resulting waste.

The disinfectant paste according to the invention contains the compound in the form of fibers.

Advantageously, the fibers may be selected from organic fibers such as cellulose fibers and mineral fibers such as mineral wool and glass wool.

The fibers can have a diameter from 2 µm to 10 µm.

The fibers can have a length from 50 µm to 10 mm.

The paste according to the invention may contain an active disinfectant agent.

The active disinfectant agent can be any active disinfectant agent that makes it possible to remove contaminating particles, whatever the nature of these contaminating particles: be it chemical, biological or even radioactive contaminating particles, in other words, the disinfecting agent can be any NRBC ((Nuclear , Radiological, Biological, Chemical) disinfecting agent, whether organic or mineral, liquid or solid, infecting compounds.

Thus, the paste according to the invention may contain a biological or chemical or radioactive, radiological disinfectant agent.

The active disinfectant agent may also be a degreasing agent or an etching agent designed to remove possible contaminating particles located on the surface and possibly below the surface and depth of the substrate.

Some disinfecting agents can perform several disinfecting functions simultaneously.

By biological disinfectant, which may also be described as a biological agent or a disinfectant, is meant any agent that, when brought into contact with biological particles, in particular toxic biological particles, is capable of inactivating or destroying them.

Biological particles refer to any type of microorganism such as bacteria, fungi, yeast, viruses, toxins, spores, in particular Bacillus anthracis spores, prions and protozoa.

The biological particles that are removed, eliminated, destroyed, inactivated by the paste according to the invention are essentially biotoxic particles, such as pathogenic spores, for example Bacillus anthracis spores, toxins, for example botulinum toxin or ricin, bacteria, for example Yersinia bacteria pestis , and viruses such as vaccinia virus or hemorrhagic fever virus such as Ebola.

By chemical disinfectant is meant any agent which, when brought into contact with chemical particles, in particular toxic chemical particles, is capable of destroying or inactivating them.

The chemical particles that are removed or eliminated by the paste according to the invention are in particular toxic chemical particles such as toxic gases, in particular neurotoxic gases or blister gases.

Toxic gases include, but are not limited to, organophosphorus compounds including, Sarin or Agent GB, VX, Tabun or Agent GA, Soman, Cyclosarin, Diisopropylfluorophosphonate (DFP), Amitone or Agent VG, Parathion. Other toxic gases are mustard gas or Agent H or Agent HD, Lewisite or Agent L, Agent T.

The radioactive particles that can be removed by the paste according to the invention can be selected, for example, from metal oxides and hydroxides, in particular in the form of a solid precipitate.

It should be noted that in the case of radioactive particles we are not talking about destruction or inactivation, but only about removal, eliminating contamination by dissolving radiating deposits or corrosion products of contaminated materials. Thus, there is a real transfer of radioactive contamination into solid waste obtained after the paste has dried.

The active disinfectant, for example, an active biological or chemical disinfectant, can be selected from bases such as sodium hydroxide, potassium hydroxide and mixtures thereof; acids such as nitric acid, phosphoric acid, hydrochloric acid, sulfuric acid; hydroxalates, such as sodium hydroxalate, and mixtures thereof; oxidizing agents such as peroxides, permanganates, persulfates, ozone; hypochlorites such as sodium hypochlorite; cerium IV salts and mixtures thereof; quaternary ammonium salts such as hexadecylpyridine (cetylpyridine) salts, for example hexadecylpyridine (cetylpyridine) chloride; reducing agents; and their mixtures.

For example, the disinfectant active agent may be a disinfectant such as bleach (“javel water”), which imparts disinfectant, biological and/or chemical control properties to the paste.

Some active disinfectant agents may fall into several categories as defined above.

So, nitric acid is an acid, but it is also an oxidizing agent.

The active disinfectant agent, such as a biocidal agent, is typically used at a concentration of 0.1 to 10 mol/L paste, preferably 0.5 to 10 mol/L paste, more preferably 1 to 10 mol/L paste , preferably from 3 to 6 mol/l of paste, to guarantee a disinfecting effect, for example, an inhibitory effect on biological particles, in particular biotoxic particles, compatible with the drying time of the paste, and to ensure, for example, drying of the paste at a temperature of 20°C up to 50°C at relative humidity from 20% to 60%, on average, for a period of 30 minutes to 5 hours.

To achieve maximum efficiency, including the most unfavorable conditions of temperature and humidity relative to drying time, the paste composition allows for different concentrations of the active agent. Indeed, it can be seen that increasing the concentration of the disinfectant, in particular an acidic or basic disinfectant, leads to a very significant increase in the drying time of the paste and, consequently, in the efficiency of the method.

The active disinfectant may be an acid or a mixture of acids. The acids are typically selected from mineral acids such as hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid.

A particularly preferred disinfectant, in particular a biological disinfectant, is nitric acid.

Indeed, it was unexpectedly discovered that nitric acid destroys and inactivates biological, in particular biotoxic, particles.

In particular, nitric acid has been surprisingly confirmed to destroy and inactivate spores, such as those of Bacillus thuringiensis , which are known to be particularly resistant.

The acid(s) are preferably present at a concentration of 0.5 to 10 mol/L, more preferably 1 to 10 mol/L, better 3 to 6 mol/L, which ensures that the paste dries generally , at temperatures from 20°C to 50°C and relative humidity from 20% to 60%, on average, for a period of 30 minutes to 5 hours.

Another preferred disinfectant is a mixture of nitric acid and phosphoric acid. Thus, the paste according to the invention may consist of a clay, such as kaolinite, and an acidic aqueous solution of nitric acid, for example 1M, and phosphoric acid, for example 1M, the clay making up, for example, from 40% to 60% by weight . relative to the weight of the paste, and the acidic aqueous solution is, for example, from 60% to 40% by weight. relative to the weight of the paste.

Alternatively, the active disinfectant, for example an active biological disinfectant, may be a base, preferably a mineral base, preferably selected from soda, potash and mixtures thereof.

In the case of such a basic composition, the paste according to the invention, in addition to its disinfecting effect, has a degreasing effect, due to which it is also possible to remove and eliminate contaminating particles that may be present on the surface of the substrate.

As mentioned above, to achieve overall effectiveness, including effectiveness in the most unfavorable weather conditions for drying the paste, the paste according to the invention can be characterized by a wide range of concentrations of the main disinfectant(s).

Indeed, increasing the concentration of the main disinfectant agent, such as NaOH or KOH, which generally acts as a biocidal agent, can greatly increase the rate of inhibition of biological particles, as has been demonstrated for Bacillus thuringiensis spores.

Advantageously, the base is present in a concentration of less than 10 mol/L, preferably 0.5 to 7 mol/L, more preferably 1 to 5 mol/L, better 3 to 6 mol/L, to ensure drying of the paste at temperature from 20°C to 50°C and relative humidity from 20% to 60%, on average, for a period of 30 minutes to 5 hours.

The disinfectant, particularly when it is a biological disinfectant, is sodium hydroxide or potassium hydroxide.

For example, with regard to spore inhibition kinetics and paste drying time as a function of temperature, the active disinfectant agent, in particular when it is a biocidal agent, is preferably sodium hydroxide at a concentration of 1 to 5 mol/l.

The paste according to the invention may optionally also contain a surfactant or mixture of surfactants, preferably selected from the family of non-ionic surfactants such as block copolymers, for example ethylene oxide and propylene oxide block copolymers, ethoxylated fatty acids and mixtures thereof.

For this type of paste, the surfactants are preferably block copolymers marketed by BASF under the name PLURONIC®.

PLURONIC® are block copolymers of ethylene oxide and propylene oxide.

These surfactants affect the rheological properties of the paste, in particular the thixotropic nature of the product, and their recovery time, and eliminate the formation of sagging.

Advantageously, the particle-contaminating agent is selected from inorganic adsorbents such as zeolites, clays, phosphates such as apatites, titanates such as sodium titanate, and ferrocyanides and ferricyanides.

An optional extracting agent such as zeolite or clay may be used in the case where the contaminating particles are radionuclides, however, an optional extracting agent may also be used in the case of contaminating particles other than radionuclides, for example metals, such as toxic metals or heavy metals .

Advantageously, the particle chelating agent is selected from n-octylphenyl-n, n-diisobutylcarbamoylmethylphosphine oxide (CMPO), tributyl phosphate (TBP), 1-hydroxyethane-1,1-diphosphonic acid (HEDPA), di-2-ethylhexylphosphoric acid (DHEPA), trioctylphosphine oxide (TOPO), diethylenetriamine pentaacetate (DTPA), primary, secondary and tertiary organic amines, cobalt dicarbolite, calixarenes, niobates, ammonium molybdophosphate (AMP), (trimethylphenyl)phosphinic acid (TPPA) and mixtures thereof.

An extracting agent can sometimes act as a chelating agent, and vice versa.

Advantageously, the coloring agent is selected from dyes, preferably organic dyes, and pigments, preferably mineral ones.

Advantageously, the pigment is a mineral pigment. In this regard, reference may be made to document WO-A1-2014/154817 [7].

There are no restrictions on the mineral pigment included in the paste according to the invention.

In general, the mineral pigment is selected from mineral pigments that are stable in paste.

By stable pigment, in general, we mean that the pigment does not change color over time when the paste is stored for at least 6 months.

There is also no limitation as to the color of the pigment, which is generally the color the paste will have. The pigment can be black, red, blue, green, yellow, orange, purple, brown, and even white.

In general, the color of the paste is identical to the color of the pigment it contains. However, it is possible that the color of the paste differs from the color of the pigment it contains, but this is not intentional.

The pigment, especially the white one, is generally different from the inorganic thickener.

Advantageously, the mineral pigment is selected so that it gives the paste, when dry, a color different from the color of the surface to which the paste is applied.

Advantageously, the mineral pigment is a fine pigment, and the average particle size of the mineral pigment may be from 0.05 to 5 μm, preferably from 0.1 to 1 μm.

Advantageously, the mineral pigment is selected from metal and/or metalloid oxides, metal and/or metalloid hydroxides, metal and/or metalloid oxide hydroxides, metal ferrocyanides and ferricyanides, metal aluminates and mixtures thereof.

Preferably, the mineral pigment is selected from oxides, preferably finely divided, and mixtures thereof.

Indeed, iron oxides can have different colors, for example they can be yellow, red, purple, orange, brown or black.

Indeed, iron oxide pigments are known to have good hiding power and high resistance to acids and bases.

From the point of view of introduction into the disinfecting paste, iron oxides are characterized by the best parameters in terms of stability and hiding power. For example, an iron oxide content of 0.1% or even 0.01% is sufficient to strongly color the paste without changing its properties.

Fine iron oxides are marketed by Rockwood® under the trade name Ferroxide®.

Mention may be made of Ferroxide® 212M, which is a fine red iron oxide with an average particle size of 0.1 microns, and Ferroxide® 228M, which is a fine red iron oxide with an average particle size of 0.5 microns.

In addition to and/or instead of iron oxides, other colored oxides or hydroxides of metals or metalloids can be added to the paste according to the invention, depending on the pH of the paste, in particular, orange-colored vanadium oxide (V ₂ O ₅ ), manganese oxide ( MnO ₂ ) is black, cobalt oxide is blue or green and oxides of rare earth elements. However, iron oxides are preferred for the reasons stated above.

Among the oxyhydroxides, we can mention goethite, that is, iron oxyhydroxide FeOOH, which has a very bright color.

With regard to metal ferrocyanides, mention may be made of Prussian blue, i.e., ferrous iron ferrocyanide, and as an example of an aluminate, mention can be made of cobalt blue, i.e., cobalt aluminate.

The solvent for the paste according to the invention is usually selected from water, organic solvents and mixtures thereof.

The preferred solvent is water, therefore, in this case the solvent consists of water, includes 100% water.

The paste corresponding to the invention, in some cases, can be defined as a so-called “resorbing” paste, and then the composition of the paste provides for supersaturation with a solution, a solvent. Such a “resorbent”, “supersaturated” paste, in particular, makes it possible to disinfect deeply contaminated porous materials. When such a paste is applied to a porous surface, part of the solvent from the paste is spontaneously absorbed into the pores of the material and dissolves the infecting particles.

It should be noted that there is no theoretical paste supersaturation coefficient. Supersaturation of a paste corresponds to its ability to lose some of the solvent (such as water) while remaining saturated. That is, the paste will shrink to compensate for the "loss" of some of the solvent (eg water), which is responsible for the supersaturation of the solvent, such as water.

Therefore, supersaturation essentially depends on the composition of the paste, that is, on the type of materials included in the paste and their concentrations.

The solution may be specifically formulated to react with the porous material to promote dissolution of the contaminating particles, substances, for example, by chemical action, chelation of the contaminating substances, etc.

First, the paste is brought into contact with the surface of a solid porous substrate to be disinfected. When an equilibrium is reached between saturation of the paste with the solution and absorption into the porous material, the paste begins to dry out as the solvent evaporates at the paste-air interface. The solution absorbed into the material is then resorbed into the paste by the action of capillary re-equilibration, while at the same time removing dissolved contaminating particles by advection and thus ensuring disinfection of the porous material.

The invention also relates to a method for disinfecting a substrate made of solid material, wherein said substrate is contaminated with at least infectious particles related to unstable contamination and/or at least infectious particles related to surface contamination located on one of its surfaces, and/or at least infecting particles related to subsurface infection located directly under the specified surface, and/or at least infecting particles located under the specified surface deep in the substrate, while at least one cycle, including the following sequential stages, in which:

a) apply the paste corresponding to the invention described above to the specified surface,

b) leave the paste on the surface for at least a time sufficient for the paste to destroy and/or inactivate and/or absorb and/or dissolve contaminating particles.

The disinfection method uses a paste according to the invention as described above, therefore the method has all the advantages inherent in the paste, which are already described above, in particular with regard to the thickness of the applied layer and the size of the resulting dry solid residues.

In particular, as already mentioned above in the context of the description of the paste, the presence in the paste according to the invention of a compound in the form of fibers, even in the small quantities indicated above, provides better internal cohesion of the paste without changing its advantageous disinfecting and drying properties. Thus, the connection in the form of fibers ensures that even with a greater thickness of the paste layer, for example greater than or equal to 5 mm, preferably greater than or equal to 6, 7, 8 or 9 mm, more preferably at least 10 mm and up to 50mm, the paste can be held on a vertical wall without sagging, and always produces solid, non-powdery waste after drying. This is shown in example 4.

The mechanism of disinfection with paste during the implementation of the method according to the invention differs depending on the type of infection.

In cases of transient, superficial or subsurface contamination, the paste is applied to the contaminated surface and the thickener ensures prolonged contact between the disinfecting solution (solvent in the paste) and the contaminated substrate.

Depending on the active disinfectant optionally included in the composition, the paste can dissolve unstable and superficial contamination, as well as corrode the substrate by several microns to dissolve subsurface contamination.

Finally, the paste dries to form a dry, solid residue at least a centimeter in size containing contaminating particles.

This mechanism is similar to that known for suction-removable gels. However, the paste according to the invention used in the method according to the invention contains a particular inorganic thickener selected from clays and a fiber-shaped compound and can be applied in a layer of much greater thickness than gels. The truly synergistic combination of these characteristics, namely, an inorganic thickener selected from clays, a fiber compound and a large thickness of the applied layer, unexpectedly makes it possible to obtain a dry solid residue having, in contrast to suction-removable gels, few or no cracks, therefore , consisting of one or more pieces much larger than the flakes of the suction-removable gel.

Indeed, the use of clays eliminates the appearance of cracks, since they are better organized during drying.

In general, in the method according to the invention, the goal is to avoid cracks, as opposed to methods that use suction-removable gels, where the goal is to create cracks.

The method according to the invention provides the possibility of fixing and immobilizing infectious particles in a solid state inside the paste, dry solid residue, thus eliminating possible release in the event of washing out the dry and solid residue.

The method according to the invention is a reliable and reproducible method, which can be described as robust to failure, and the effectiveness of the method depends little on how the paste is applied. Thus, unlike suction gels, which require precise control of their application by spraying, and due to their ability to adhere well to the wall, the pastes according to the invention can be applied to the contaminated surface manually, for example using a trowel or, preferably, using a sprinkler like mortar or coating.

The substrate, made from a solid material, may be a porous substrate, preferably a porous mineral substrate.

However, the effectiveness of the paste and the method according to the invention is also high in the case of a dense, non-porous and/or non-mineral surface.

Advantageously, the substrate is made of at least a solid material selected from metals, metal alloys such as stainless steel, painted steels, aluminum and lead; polymers such as plastic materials or rubbers, such as polyvinyl chloride(s) or PVC, polypropylenes or PP, polyethylenes or PE, in particular high density polyethylenes or HDPE, polymethyl methacrylates or PMMA, polyvinylidene fluorides or PVDF, polycarbonates or PC; glass; cements or binders; cement mortars and concretes; plasters; bricks; natural and artificial stone; ceramics.

Advantageously, the contaminating particles are selected from the chemical, biological, radioactive or radiological contaminating particles already listed above, in particular from the toxic biological particles already listed above.

Advantageously, the paste is applied to the surface to be disinfected in an amount of from 2000 g to 50,000 g of paste per m ² of surface, preferably from 5,000 g to 10,000 g of paste per m ² of surface, which corresponds approximately to a paste layer thickness of from 2 to 50 mm per m ² surface, preferably from 5 to 10 mm per m ² surface.

Advantageously, as already shown above, the paste can be applied to the surface manually, for example with a trowel, or using a spray machine.

Advantageously (in step b), drying is carried out at a temperature of 1°C to 50°C, preferably 15°C to 25°C, and a relative humidity of 20% to 80%, preferably 20% to 70%.

Advantageously, the paste is left on the surface for a period of 2 to 72 hours, preferably 2 to 48 hours.

Advantageously, the dry and solid residue is in the form of one or more pieces, each of which has a size (as determined by its largest dimension) greater than or equal to 1 cm, preferably greater than or equal to 2 cm, more preferably greater than or equal to 5 cm.

Preferably, the dry and solid residue is removed from the hard surface mechanically, for example, by brushing.

Advantageously, the above cycle can be repeated, for example, 1 to 10 times, using the same paste in all cycles or different pastes in one or more cycles.

Advantageously, in step b), the paste is moistened before complete drying with a solution, for example, a solution of a disinfecting agent, preferably a solution of the active disinfecting agent of the paste applied in step a), in the solvent of this paste, due to which, in general, repetition of application of the paste to the surface is eliminated, The reagent is saved and the amount of waste is limited. The additional humidification operation can be repeated, for example, from 1 to 10 times.

Advantageously, the paste applied in step a) may be a solvent supersaturated paste (see above), in particular when the substrate is made of a porous solid material.

The method according to the invention may be called a "regenerative" method, since it uses a paste that is converted into dry and solid waste, a residue which can advantageously be regenerated to produce a new paste according to the invention, which, if desired, can be again used in the method according to the invention.

The dry and solid waste residue, for the purpose of its regeneration, can be brought into contact with a solution containing a solvent and, optionally, one or more of the optional components mentioned above, thereby obtaining a paste according to the invention as described above, for example , dry and solid waste, the residue, can be brought into contact with a solution of a disinfectant agent.

In the method according to the invention for disinfecting a substrate made of a solid material, in particular when the substrate is made of a porous material, no pre-impregnation of the substrate is required, in particular due to the effective control of supersaturation (see above) of the paste according to the invention.

We summarize that the method and paste corresponding to the invention, among other things, have the following favorable properties in addition to those already described above:

- ease of application of the paste,

- adhesion to walls and ceilings,

- obtaining maximum disinfection efficiency at the end of the drying phase of the paste, including the case of penetrating infection, in particular the case of porous surfaces.

In general, it is guaranteed that the drying time is greater than or equal to the time period required for inactivation. In case of deep inactivation, you can resort to additional moisture.

- processing of a very wide range of materials,

- absence of mechanical or physical damage to materials upon completion of processing,

- application of the method in different weather conditions,

- reduction of waste volume,

- ease of disposal of dry waste.

In conclusion, we note that the options for using the paste and the method for surface, subsurface and deep disinfection, in particular of porous materials in accordance with the invention, are numerous and varied. One specific target application relates to the radioactive decontamination of cementitious materials to minimize the amount of waste generated during end-of-life remediation and dismantling of nuclear facilities.

However, the problem of decontamination of porous materials also arises in other areas of activity, such as industries that use toxic chemicals, decontamination after NRBC incidents, architectural conservation of historical monuments, and even in the context of dismantling public buildings contaminated with e.g. molecules, heavy metals, microorganisms, asbestos, soot particles after a fire, etc.

Other features and advantages of the invention will become apparent upon reading the following detailed description, which is intended to be explanatory and non-limiting in nature, in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In fig. 1 shows a photograph of paste 1 prepared in Example 1 in a container.

In fig. Figure 2 shows a photograph of paste 2, prepared in example 1, in a container.

In fig. 3A, 3B and 3C are photographs of the applied paste layer 3 (FIG. 3A), the applied paste layer 1 (FIG. 3B), and the applied paste layer 4 (FIG. 3C) on the surface of a vertical cement wall. The thickness of the applied layers of paste is 10 mm.

DETAILED DESCRIPTION OF SPECIFIC OPTIONS FOR IMPLEMENTING THE INVENTION

The paste according to the invention can be easily prepared at room temperature.

For example, the paste according to the invention can be prepared by adding, preferably gradually, (sequentially in any order and/or simultaneously) inorganic thickener(s) and a fiber compound to a solvent such as water, preferably deionized water, or a mixture of a solvent and one or more components selected from those already listed above, namely: a surfactant, an active disinfectant, a particle-extracting agent, a particle-chelating agent and a coloring agent.

Mixing can be accomplished by mechanical stirring, for example using a mechanical stirrer equipped with a three-bladed impeller. The rotation speed is, for example, 200 rpm, the mixing time is, for example, 3 to 5 minutes.

Addition of the inorganic thickener(s) and the fiber compound to the solvent or mixture of the solvent and the above-mentioned component(s) can be accomplished simply by pouring the thickener(s) and the fiber compound into the said mixture, sequentially in any order or simultaneously. Upon addition of the inorganic thickener(s) and/or fiber compound, a mixture containing the solvent, the inorganic thickener(s) and/or fiber compound, and optionally the specified the above component(s) are typically subjected to mechanical agitation.

Mixing can be carried out, for example, using a mechanical stirrer equipped with a three-blade impeller.

The rotation speed is typically gradually increased as the viscosity of the solution increases, eventually reaching a rotation speed of, for example, 400-600 rpm when the inorganic thickener(s) and compound in the form of fibers, without splashing.

Once the addition of the inorganic thickener(s) and the fiber compound has been completed, mixing is continued for eg 2 to 5 minutes to obtain a completely homogeneous paste.

The paste thus obtained is left for at least an hour before use.

It is obvious that other protocols for the preparation of pastes according to the invention can be applied, providing for the addition of the paste components in a different order than the one indicated above, and/or the simultaneous addition of several components.

It should be noted that the optional surfactant in the paste according to the invention has a beneficial and significant effect on the rheological properties of the paste according to the invention. In particular, the surfactant eliminates the risk of spreading or sagging when treating vertical surfaces or ceilings.

The paste according to the invention thus prepared is then applied to a hard surface of a substrate made of solid material to be disinfected, in other words, to a surface that has become contaminated, for example biologically contaminated. The infection has already been described above. In particular, a biological contamination may consist of one or more of the types of biological particles defined above.

As stated above, the disinfectant active agent, eg the biological active disinfectant agent, is selected depending on the contaminating particles, eg biological particles, to be removed, eliminated, destroyed or inactivated.

With the possible exception of light metal alloys such as aluminum in the case of a basic or acidic paste, there are no restrictions on the material from which the substrate to be disinfected is formed. Indeed, with the paste according to the invention, all types of materials, even fragile ones, can be processed without any harm to them.

The paste corresponding to the invention does not cause any chemical, mechanical or physical damage, does not cause erosion or corrosion of the treated substrate.

However, in the case of subsurface decontamination operations, corrosion of the substrate is limited to a few microns, as is the case with suction-removable gels.

Consequently, the paste according to the invention is harmless to the integrity of the processed substrates and does not even preclude their reuse. Thus, sensitive materials, such as military equipment, remain intact and can be used again after disinfection, while monuments treated with the paste according to the invention are not damaged at all and retain their visible and structural integrity.

Therefore, the substrate material can be selected, for example, from metals and alloys such as stainless steel, aluminum and lead; polymers such as plastic materials or rubbers, of which mention may be made of PVC, PP, PE, in particular HDPE, PMMA, PVDF and PC; glass; cements and binding materials; cement mortars and concretes; plasters; bricks; natural or artificial stone; ceramics.

In all cases, whatever the material, the effectiveness of disinfection with the paste according to the invention is significant.

The surface to be treated can be painted or unpainted.

The effectiveness of treatment with the paste according to the invention is generally significant, including substrates contaminated to a depth of several millimeters.

There are no restrictions on the shape, geometry and size of the substrate and surface to be disinfected; The paste according to the invention and the method of its use make it possible to process large surfaces with complex geometries, for example, with cavities, corners and recesses.

The paste according to the invention provides effective treatment not only of substrates with a horizontal surface, such as floors, but also of substrates with a vertical surface, such as walls, or an inclined or overhanging surface, such as ceilings.

Compared to decontamination methods, for example biological decontamination methods, which use liquids such as solutions, the decontamination method of the invention using a paste is particularly well suited for treating large surface areas, non-transportable materials and outdoor treatments. Indeed, the method according to the invention, thanks to the use of a paste, allows for on-site disinfection, while eliminating the spread of chemical solutions in the environment and the dispersion of infectious particles.

The paste according to the invention can be applied and distributed over the surface to be treated by any application method known to those skilled in the art.

Common methods are hand application, such as with a trowel, or application using a sprinkler such as grout or coating.

The fairly short recovery time of the viscosity of the paste according to the invention allows the applied paste to adhere to a surface, for example, a wall.

The amount of paste applied to the surface to be treated is generally from 2000 to 50,000 g/ ^m2 , preferably from 5000 to 10,000 g/ ^m2 . The amount of paste applied per unit surface and, accordingly, the thickness of the applied layer of paste affects the drying speed.

Thus, when a layer of paste 2 to 10 mm thick is applied or sprayed onto the surface of the substrate to be treated, the effective contact time of the paste and materials is equivalent to the drying time, the period of time during which the active component present in the paste interacts with the contamination.

In addition, it has surprisingly been shown that the amount of paste applied - wherein the paste additionally contains a certain thickener selected from clays - when greater than or equal to 2000 g/ ^m2 , in particular, is from 5000 to 10000 g/ ^m2 , which corresponds to the minimum thickness of the applied layer of paste, for example, greater than or equal to 2000 μm (2 mm) for an applied amount of paste greater than or equal to 2000 g/m ² , allows, after drying of the paste, to obtain a dry and solid residue in the form of one or several large pieces (with herein, the size is determined by the largest dimension of the piece or pieces), with the size of each piece being greater than or equal to 1 cm, preferably greater than or equal to 2 cm, more preferably greater than or equal to 5 cm.

The amount of paste applied and therefore the thickness of the applied paste layer, preferably greater than or equal to 2000 g/m ² , that is, 2000 µm, in combination with the special nature of the thickener used in the paste according to the invention (see above), is fundamental a parameter that influences the size of the dry residue formed after the paste has dried, and which ensures that a dry and solid residue is formed in the form of one or more large pieces, with the size of each piece being greater than or equal to 1 cm, and there are no dry residues of millimeter size size or powdery residues. The resulting dry and solid residue in the form of one or several large pieces is easily removed mechanically.

However, it should also be noted that if the paste contains a surfactant in low concentration, usually from 0.1% to 2% of the total weight of the paste, the drying time of the paste is improved, which leads to easier separation of the solids from the base.

The paste is then left on the surface to be treated for as long as necessary to dry. In the drying step, which can be considered as the active step of the method according to the invention, the solvent contained in the paste, which is generally the water present in the paste, evaporates to form a dry and solid residue.

Drying time depends on the composition of the paste within the concentration ranges of its components given above, and also, as already indicated, on the amount of paste applied per unit area, that is, on the thickness of the applied layer of paste.

Drying time also depends on weather conditions, that is, the temperature and relative humidity of the atmosphere in which the surface of the substrate made of solid material is located.

The method according to the invention can be carried out in a very wide range of weather conditions, namely at temperatures T from 1°C to 50°C and relative humidity RH from 20% to 80%.

Thus, the drying time of the paste according to the invention is generally from 1 hour to 48 hours at a temperature T of 1°C to 50°C and a relative humidity RH of 20% to 80%.

It should be noted that the paste composition according to the invention, in particular when it contains surfactants such as Pluronics®, generally provides a drying time substantially equivalent to the contact time (between the disinfecting agent, such as a biological agent, and the infectious particles, for example, biological, in particular biotoxic particles to be removed, eliminated), which is required to inactivate and/or absorb contaminating particles contaminating the substrate material and/or to undergo sufficient erosion reactions on the surface of the material.

In other words, the paste composition provides a drying time that is nothing other than the inactivation time of the infecting particles, for example, biological particles, which is comparable to the kinetics of inhibition of infection, for example, biological contamination.

Or the paste composition provides a drying time, which is nothing more than the time necessary for the erosion reactions underlying the removal of the contaminated surface layer of the material to occur.

In the case of radioactive contaminating particles, the contamination is removed by dissolving the radiating deposits or by corroding the contaminating materials. Thus, there is a real transfer of radioactive contamination into the dry solid residue.

The surface area of the commonly used mineral filler, which is generally from 50 m ² /g to 300 m ² /g, preferably 100 m ² /g, and the absorption capacity of the paste according to the invention, allow the capture of unstable (surface) and non-volatile contamination material constituting the surface to be treated.

If necessary, contaminating particles, for example biological contaminating particles, are inactivated in the paste phase. After the paste has dried, the contamination, such as inactivated biological contamination, is removed by separating the dry residue of the paste as described above.

Once the paste has dried, the dry paste forms a dry residue that crumbles slightly or does not crumble, unlike the dry residue of gels that are removed by suction. This dry residue includes one or more large pieces. The dry residue may contain inactivated infectious particles.

The dry residue obtained after the paste has dried is characterized by low adhesion to the surface of the disinfected material. Consequently, the dry residue obtained after the paste has dried can be easily separated by a simple mechanical method, for example, by brushing. However, the dry residue can also be removed with a gas jet, for example a compressed gas jet.

Thus, in general, there is no need for washing with water, and in the method according to the invention, no secondary liquid effluents are generated.

However, it is possible, although not preferred, if desired, to remove the dry residue with a jet of liquid.

Thus, the method according to the invention provides, firstly, significant savings in chemical reagents compared to the disinfection method by washing with a solution. Secondly, since the waste is generated in the form of a dry residue, which can be easily removed mechanically, the washing operation with water or liquid, usually necessary to remove traces of chemical reagents, is generally eliminated. This obviously leads to a reduction in the amount of waste generated, as well as to a significant simplification in terms of waste treatment and disposal.

Due to the predominantly mineral composition of the paste according to the invention and the small amount of waste generated, dry waste can be stored or directed to an outlet channel ("outlet") without pre-treatment.

At the end of the method according to the invention, the solid waste is discharged in the form of one or more large pieces of dry paste, which can be packaged as such, directly, therefore, as stated above, the amount of waste generated is significantly reduced, and also a significant simplification in the channel part is achieved waste treatment and release.

In addition, in the nuclear field, the fact that the solid solids do not need to be processed before packaging the waste is a significant advantage and allows the use of highly effective active agents that until now could not be used in disinfection liquids due to technological limitations in liquid waste treatment plants (liquid effluent treatment plant, LETP).

Therefore, the paste may contain strong oxidizing agents such as cerium IV, which can be easily regenerated by electrolysis of cerium III.

For example, in the general case, when 2000 g of paste is applied per square meter of the treated surface, the weight of the resulting dry waste is less than 1400 g/ ^m2 .

EXAMPLES

Example 1

This example describes the preparation of two pastes for surface, subsurface and deep disinfection, called “paste 1” and “paste 2”, corresponding to the invention.

Paste 1 is a paste with the following composition:

- 0.8% wt. (relative to the total weight of the paste) Cellulose BC 1000 (fibers approximately 700 µm) marketed by Arbocel®;

- 49.6% wt. (relative to the total weight of the paste) koalinite marketed by Sigma-Aldrich®;

- 49.6% wt. (relative to the total weight of the paste) deionized water.

Paste 2 is a paste with the following composition:

- 8% wt. (relative to the total weight of the paste) Cellulose BC 1000 (fibers approximately 700 µm) marketed by Arbocel®;

- 20% wt. (relative to the total weight of the paste) koalinite marketed by Sigma-Aldrich®;

- 72% wt. (relative to the total weight of the paste) deionized water.

The synthesis protocol is the same for both pastes:

- first weigh the deionized water in a suitable container,

- then kaolinite and cellulose were gradually added to the water, stirring using a three-blade mechanical stirrer until a homogeneous mixture without lumps was obtained.

Finally, the pastes thus obtained were continued to be stirred for a few more minutes.

In fig. 1 shows a photograph of the resulting paste 1.

In fig. 2 shows a photograph of the resulting paste 2.

Each of these pastes had a plastic structure that made it possible to apply it to a surface, such as the wall of an object, either manually or using a spraying machine such as cement mortar or coating.

Example 2

This example demonstrates the effectiveness of the paste according to the invention, namely paste 1 prepared in example 1, for surface, subsurface and deep disinfection of porous material.

More specifically, in this example, the disinfection of a porous material consisting of a group of glass beads deeply contaminated with ¹³³ Cs with a disinfection paste according to the invention was studied.

The disinfectant paste according to the invention used in this example was paste 1 prepared in example 1.

The porous material used was glass beads ranging in size from 45 µm to 90 µm, which was prepared in a round crystallizer with a diameter of 9.1 cm.

The group of glass beads thus created, the height of which was 2 cm, was impregnated and saturated with 43.42 ml of an aqueous solution of CsNO ₃ with a CsNO ₃ concentration of 0.016 M. The glass bead group contained 93 mg of ¹³³ Cs.

Then 2 cm of paste 1 was placed on a group of glass beads saturated with the solution. The whole thing was then allowed to dry under ambient conditions. After a week of drying, the remaining solid waste after paste 1 had dried was separated from the group of glass beads. The glass beads were removed and washed with 0.1 M NaOH solution. The wash solution was then analyzed by atomic absorption spectroscopy to determine the amount of Cs remaining in the group of glass beads and thus study the effectiveness of the method. Analysis of the wash solution showed the presence of 63.2 mg Cs. Thus, the disinfection step resulted in the removal of 68% of the contaminating substances, that is, ¹³³ Cs, present in the group of glass beads.

Paste 1 dried and adsorbed the aqueous solution through capillary action. The contaminating substances, that is, ¹³³ Cs, were absorbed from the porous material into the paste 1 by advection.

This example clearly demonstrates that the "reabsorbent" pastes according to the invention have the ability to disinfect porous materials contaminated simultaneously at the surface, in the subsurface layer and at great depths.

Example 3

In this example, the fixation of contamination in the final solid waste obtained after disinfection with a paste according to the invention was studied. Clay has been demonstrated to play a significant role as a thickening agent as well as a contamination inhibitor. More specifically, this example demonstrates the ability of the pastes according to the invention to fix contamination in a dry paste obtained after a disinfection operation.

For this purpose, 1 g of kaolinite marketed by Sigma-Aldrich® was soaked in 4 ml of Cs solution. Various samples were prepared with different concentrations of Cs, namely: 10 ^-1 M, 10 ^-2 M, 10 ^-3 M and 10 ^-5 M. The samples were allowed to dry until completely evaporated, then suspended in 100 ml with stirring for 24 hours. After these 24 hours, the solution was filtered and the Cs content was analyzed by atomic absorption spectroscopy, after which it was compared with the amount of Cs introduced per gram of kaolinite. The Cs content remaining in the clay was then calculated, expressed in %. The results are summarized in Table 1 below.

Table 1: Fixation of Cs with clay (kaolinite)

Concentration of Cs in the impregnation solution m _Cs in H ₂ O after suspension %Cs remaining in clay 10 ^-1 M 4.4⋅10 ^-2 g 13% 10 ^-2 M 3.97⋅10 ^-3 g 22% 10 ^-3 M 2.84⋅10 ^-4 g 47% 10 ^-5 M Below device detection level ≈ 100%

The percentage of Cs remaining in the clay depends on the initial amount of Cs added, which can be explained by the saturation of fixing sites.

The test carried out with a concentration of Cs 10 ^-5 can be considered as the most representative of radioactive contamination due to the small amount of contaminating substance present. In this case, it was observed that almost all of the contaminant (ie, Cs) could be fixed in the clay.

In conclusion, it should be noted that in the case of the paste used for the Cs disinfection operation, clay turned out to be indispensable, acting as both a thickener and a contamination fixer.

Example 4

This example demonstrates that the pastes according to the invention can be held on a vertical wall even when applied in a layer of significant thickness due to the presence of a fiber-shaped compound.

We prepared two new pastes (following the same protocol as in example 1):

- paste 3, not corresponding to the invention, of the following composition: 50% wt. kaolinite, brought to market by Sigma-Aldrich®, and 50% wt. deionized water,

- paste 4, corresponding to the invention, of the following composition: 2.4% wt. Cellulose BC 1000, manufactured by Arbocel®; 48.8% wt. kaolinite, brought to market by Sigma-Aldrich®; 48.8% wt. deionized water.

In fig. 3A, 3B and 3C are photographs of the applied paste layer 3 (FIG. 3A), the applied paste layer 1 (FIG. 3B), and the applied paste layer 4 (FIG. 3C) on the surface of a vertical cement wall. The thickness of the applied layers of paste was 10 mm.

In fig. 3A, 3B and 3C it can be seen that in the absence of cellulose fibers, the paste (in this case, paste 3, not in accordance with the invention) does not adhere to a vertical surface in a layer of great thickness. The addition of cellulose fibers in small quantities (paste 1 and paste 4 according to the invention) helps to keep the paste on the vertical wall even with a large thickness of the paste layer, in particular at least 10 mm.

In addition, upon completion of drying of the paste 1 and paste 4 according to the invention, non-powdery solid waste is obtained in a size similar to that which was when applied; No cracks were observed in the solid waste.

In other words, the non-powdery solid waste was the same centimeter size as the wet paste layer, confirming that the presence of fibers does not have a negative effect on the size of the final waste.

CONTRASTING MATERIALS

[1] US-A1-2012/0121459

[2] WO-A2-2007/039598

[3] WO-A2-2004/008463

[4] EP-A2-0642846

[5] WO-A1-2010/037809

[6] US-B2-7,737,320

[7] FR-A1-2 967 422

particle-contaminating agents extracting agents and/or particle-contaminating chelating agents.

sagging gels removed by suction

restoration - restoration time

effluent - drain

Claims (41)

1. Disinfecting paste containing: - at least one inorganic thickener selected from clays, wherein said inorganic thickener constitutes from 20 to 70% by weight. the total weight of the paste, wherein said inorganic thickener is in the form of particles of micron and/or nanoscale size; - at least one connection in the form of fibers; the rest is solvent. 2. Disinfecting paste according to claim 1, additionally containing one or more components selected from the following: - at least one surfactant; - at least one active disinfecting agent; - at least one particle-extracting agent; - at least one chelating agent for infectious particles; And - at least one coloring agent. 3. Disinfecting paste according to claim 1 or 2, in which the specified component(s) are present in the following quantitative ratio: - from 0.1 to 8 or 10% by weight, preferably from 0.1 to 5% by weight, more preferably from 0.5 to 5% by weight, preferably from 1 to 5% by weight, even better from 1 to 3% wt. relative to the weight of the paste of at least one fiber-shaped compound; - optional, from 0.1 to 2% wt. relative to the weight of the paste of at least one surfactant; - optional, from 0.1 to 10 mol/l paste, preferably from 0.5 to 10 mol/l paste, more preferably from 1 to 10 mol/l paste, preferably from 3 to 6 mol/l paste, at least , one active disinfectant agent; - optional, from 0.1 to 5% wt. relative to the weight of the paste of at least one particle-extracting agent; - optional, from 0.1 to 5% wt. relative to the weight of the paste of at least one chelating agent; - optional, from 0.01 to 10% wt., preferably from 0.1 to 5% wt. relative to the weight of the paste of at least one coloring agent; - the rest is solvent. 4. The disinfectant paste according to any one of the preceding claims, wherein the fibers are selected from organic compound fibers such as cellulose fibers and mineral compound fibers such as mineral wool and glass wool. 5. The paste according to any one of the preceding claims, wherein the active disinfectant is selected from bases such as sodium hydroxide, potassium hydroxide, and mixtures thereof; acids such as nitric acid, phosphoric acid, hydrochloric acid, sulfuric acid; hydroxalates, such as sodium hydroxalate, and mixtures thereof; oxidizing agents such as peroxides, permanganates, persulfates, ozone; hypochlorites such as sodium hypochlorite; cerium IV salts and mixtures thereof; quaternary ammonium salts, such as hexadecylpyridine (cetylpyridine) salts, for example hexadecylpyridine (cetylpyridine) chloride; reducing agents; and their mixtures. 6. Paste according to any one of the preceding claims, wherein the surfactant is selected from the family of non-ionic surfactants, such as block copolymers, for example block copolymers of ethylene oxide and propylene oxide, ethoxylated fatty acids and mixtures thereof. 7. The paste according to any one of the preceding claims, wherein the particle-contaminating agent is selected from inorganic adsorbents such as zeolites, clays, phosphates such as apatites, titanates such as sodium titanate, and ferrocyanides and ferricyanides. 8. The paste according to any one of the preceding claims, wherein the particle chelating agent is selected from n-octylphenyl-n, n-diisobutylcarbamoylmethylphosphine oxide (CMPO), tributyl phosphate (TBP), 1-hydroxyethane-1,1-diphosphonic acid (HEDPA), di-2-ethylhexylphosphoric acid (DHEPA), trioctylphosphine oxide (TOPO), diethylenetriamine pentaacetate (DTPA), primary, secondary and tertiary organic amines, cobalt dicarbolite, calixarenes, niobates, ammonium molybdophosphate (AMP), (trimethylphenyl)phosphinic acid (TPPA) and mixtures of them. 9. Paste according to any one of the preceding claims, in which the coloring agent is selected from organic dyes and mineral pigments, preferably finely dispersed, such as metal and/or metalloid oxides, metal and/or metalloid hydroxides, metal and/or metalloid oxide hydroxides, ferrocyanides and metal ferricyanides, metal aluminates, and mixtures thereof. 10. Paste according to any one of the preceding claims, in which the solvent is selected from water, organic solvents and mixtures thereof. 11. Paste according to any one of the previous paragraphs, supersaturated with solvent. 12. A method for disinfecting a substrate made of solid material, wherein said substrate is contaminated with at least infectious particles related to unstable contamination and/or at least infectious particles related to surface contamination located on one of its surfaces, and/or at least contaminating particles related to subsurface contamination located directly under the specified surface, and/or at least contaminating particles located under the specified surface deep in the substrate, while at least , one cycle, including the following sequential stages, in which: a) apply the paste according to any one of paragraphs to the specified surface. 1-11; b) leave the paste on the surface for at least a time sufficient for the paste to destroy and/or inactivate and/or absorb and/or dissolve the contaminating particles and for the paste to dry and form a dry and solid residue containing said contaminants particles; c) remove dry and solid residue containing said infectious particles. 13. The method according to claim 12, wherein the substrate is a porous substrate, preferably a porous mineral substrate. 14. The method according to claim 12 or 13, in which the solid material is selected from metals and metal alloys such as stainless steel, painted steels, aluminum and lead; polymers such as plastic materials or rubbers, such as polyvinyl chloride(s) or PVC, polypropylenes or PP, polyethylenes or PE, in particular high density polyethylenes or HDPE, polymethyl methacrylates or PMMA, polyvinylidene fluorides or PVDF, polycarbonates or PC; glass; cements or binders; cement mortars and concretes; plasters; bricks; natural and artificial stone; ceramics. 15. Method according to any one of paragraphs. 12-14, wherein the contaminating particles are selected from chemical, biological, radioactive or radiological contaminating particles. 16. The method of claim 15, wherein the infecting particles are biological particles selected from, for example, bacteria, fungi, yeast, viruses, toxins, spores, prions and protozoa. 17. Method according to any one of paragraphs. 12-16, in which the paste is applied to the surface in an amount of from 2000 to 50,000 g of paste per m ² of surface, preferably from 5,000 to 10,000 g of paste per m ² of surface, which corresponds approximately to a paste layer thickness of from 2 to 50 mm per m ² surfaces, preferably 5 to 10 mm per m ² surface. 18. Method according to any one of paragraphs. 12-17, in which in step b) drying is carried out at a temperature of from 1 to 50°C, preferably from 15 to 25°C and a relative humidity of from 20 to 80%, preferably from 20 to 70%. 19. Method according to any one of paragraphs. 12-18, in which the paste is left on the surface for a period of 2 to 72 hours, preferably from 2 to 48 hours. 20. Method according to any one of paragraphs. 12-19, wherein the dry and solid residue is in the form of one or more pieces, each of which has a size greater than or equal to 1 cm, preferably greater than or equal to 2 cm, more preferably greater than or equal to 5 cm. 21. Method according to any one of paragraphs. 12-20, in which the dry and solid residue is removed from the hard surface by mechanical means, for example by brushing. 22. Method according to any one of paragraphs. 12-21, in which the described cycle is repeated from 1 to 10 times using the same paste in all cycles or different pastes in one or more cycles. 23. Method according to any one of paragraphs. 12-22, in which the paste applied in step a) is a paste supersaturated with solvent.