DE2305951A1 - METHOD OF MANUFACTURING A BACTERICIDE FOR WATER TREATMENT - Google Patents

Description

The present invention relates to a process for the preparation of bactericides for water treatment, which can be used in devices such as water purifiers, water coolers or rice cookers. Also concerns the invention discloses a method for treating water with the bactericides produced by this process.

Since the supply of high quality water has recently become problematic, there is a large one Need for household water purifiers. Has filtered water However, after using activated carbon using a commercially available water purifier of chlorine and Bleach powder was exempt, no bactericidal effect. In those parts of the water purifier in which the filtered This means that bacterial growth can occur. The main purpose of household water purifiers is there namely in removing contaminants and the smell of bleach powder from tap water. That from Impurities and tap water that has been freed from the bleach powder odor, however, has a reduced bactericidal effect.

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kung. On the other hand you have to prevent the water taste by renewing the previously degraded bactericidal Effect of service water suffers, or that chemical pollution caused by the addition of a bactericide occurs.

The present invention provides very reliably effective bactericides suitable for water treatment in the form of silver salts, in particular silver chloride (AgCL), silver iodide (Agj) or silver bromide (AgBr), in which the bactericidal effect of the silver ion is exploited.

There are several silver salts useful as bactericides; according to the invention, however, they are used with caution on the solubility of silver chloride, silver bromide and silver iodide. The following explanation refers to an example on silver chloride.

When using commercially available silver chloride powders as a bactericide, there are the following problems

“1), There are excess chlorine ions behind;

Z) silver chloride of uniform particle size cannot be produced;

3) the silver ions cannot always be obtained in a constant amount; and

k) Chemical contamination occurs as a result of the discharge of silver chloride powders.

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The commercially available silver chloride is produced by adding sodium chloride or hydrochloric acid to an aqueous silver nitrate solution. The excess chlorine ions thereby bring silver chloride to precipitate, i) ie water solubility of AgCl is about 10 ^-5 mol / liter; Silver chloride therefore hardly dissolves in water. However, in order to increase the efficiency of silver chloride, it is generally produced with excess chlorine ions. A considerably high proportion of chlorine ions is thus adsorbed in the silver chloride crystals and remains there.

It is also difficult, as mentioned, even with extremely strict control of the reaction conditions, im The course of the reaction to produce a silver chloride with a uniform particle size. They also need high manufacturing costs be accepted. Commercially available AgCl of special quality contains only less than 5 Gew .- ^ finely powdered fractions with a particle size below 0.1 ^ 9 mm (<T 100 mesh). When grinding the powder with a larger particle size than 0.149 now these tend to be more likely to form aggregates, so that coarse powders are obtained. In order to obtain uniformly fine particles, the Particle size can be controlled in the course of the reaction.

When immersing silver chloride powder as a bactericide in water, the following amount of silver was dissolved:

Fig. 1 shows the relationship between the solubility of the silver ions or the chlorine ions (after AgCl of a special quality with a particle size of less than 0.149 mm was immersed in water for 2k hours at 30 ° C) and the AgCl immersed in the water. Weight amount. From Fig. 1 it can be seen that the silver!

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in contrast, it becomes higher »starting from the solubility product of the AgGl, this means that there is excess in AgCl powders Remaining chlorine ions.

Unless, as stated above, there is no correlation between the amount of silver chloride added and can produce the dissolved silver tone content, this means a very serious disadvantage, if a water treatment with the help of a predetermined amount of bactericide is to be carried out. Also from the point of view in terms of chemical contamination, this deficiency is undesirable. In the V. St. A. the standard silver ion concentration is in terms of water quality less than 0.000005% ( <50 ppb) o From a defined weight or surface unit of silver chloride A certain and constant amount of silver ions must be released. As commercial silver chloride, however contains excess chlorine ions and since the adsorbed chlorine ion content is not constant even if the Unit weight or surface area of silver chloride Prescribed it is difficult to always maintain a certain fixed silver ion concentration. Thus, if there are too many silver ions, chemical contamination occurs, while if there is, too low amount of silver ions no killing of bacteria takes place. ·

The difficulties involved in achieving this when using commercially available silver chloride powders were explained A constant solubility of the silver ions hinder, in the following the by the outflow of the silver chloride powder the disadvantages caused. When using fine silver chloride powders for water treatment

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These come due to changes in the water pressure, as a result of the divergence of the meshes of the filter fabric, because of the limited useful life of this fabric, among other things. into the filtered water. This creates the danger evoked a chemical contamination. Since even with the commercially available water purifiers often particles If activated carbon gets into the filtered water, it is dangerous to add powdered silver chloride or allow the powders to adhere to the surface of the activated carbon by coating or adsorption.

According to the invention, a bactericide for water treatment is produced by removing the excess that Halogen in a silver salt exceeding the stoichiometric amount from the group consisting of silver chloride, silver bromide and silver iodide.

Furthermore, according to the present invention, a bactericide for water treatment is produced by extracting a silver salt the group of silver chloride, silver bromide and silver iodide heated to the amount exceeding the stoichiometric amount remove excess halogen.

Furthermore, according to the present invention, a bactericide for water treatment is produced by extracting a silver salt of the group of silver chloride, silver bromide and silver iodide to a temperature higher than the melting point of the relevant, The silver salt is heated or the salt melts in order to remove the excess halogen present in the silver salt.

In addition, according to the present invention, a bactericide for water treatment is produced by adding a powdery silver salt from the group of silver chloride, silver bromide and

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Silver iodide to a temperature higher than the melting point of the silver salt in question is heated or the salt melts, in order to split off and remove the excess halogen adsorbed on the salt, and then the silver salt treated in this way is shaped or pressed. -

Furthermore, according to the invention, a bactericide for water treatment is produced by pressing a powdery silver salt from the group consisting of silver chloride, silver bromide and silver iodide into a thin plate with a specific shape and thermally treating the silver salt ₉ to remove the excess halogen adsorbed on the salt. ,.

Furthermore, a bactericide for the Water treatment is made by making a silver salt of the group of silver chloride, silver bromide and silver iodide, which is sparingly soluble in water "melts" part of a cooled rotor or a cooled rotating drum in immersing the surface area of the molten silver salt, around a thin film of the silver salt on the rotor surface to produce, this thin film peeled off or scraped off the rotor and then the thin film with With the help of a roller it continuously rolls into a thin sheet of silver salt with a given thickness.

In addition, a bactericide for the Water treatment is created by adding a silver salt from the group consisting of silver chloride, silver bromide and silver iodide, which is sparingly soluble in water, deposited by vacuum evaporation on a substrate or carrier, which (r) is non-reactive towards the silver salt.

Finally, the invention relates to the treatment of

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Water with the bactericide prepared as described above.

Fig. 1 is a characteristic graph showing the relationship between the amount of in water immersed silver chloride powder and the dissolved Shows silver ion or chlorine ion content. Fig. 2 is a characteristic graph showing the relationship between the surface of silver chloride produced according to the invention and that dissolved out in the water Illustrates amount of silver ions. 3 shows an embodiment for carrying out the bactericide production method according to the invention .

According to the present invention, bactericides for water treatment can be used with very reliable effect in can be produced in a simple manner, which have a constant silver ion solubility with a constant surface area or constant Maintain amount of silver salt and which do not cause chemical pollution.

According to the invention, bactericides for the Water treatment produced by using a silver salt from the group of silver chloride, silver bromide and silver iodide heated to the excess, the stoichiometric portion remove excess halogen.

The invention is explained in more detail below with reference to silver chloride.

First, the silver chloride powder is heated to a temperature higher than the melting point (455 ° C.) in order to produce the powder

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to melt. This removes the adsorbed excess Chlorine split off and removed. The commercially available silver chloride powder a remarkably strong chlorine odor emanates in this melting stage; one recognizes by the Odor development and optically that chlorine escapes.

In the next stage, the aforementioned molten silver chloride is processed into bodies with the desired shape and size. In the case of a high production rate, the molten silver chloride is first formed into plates and the formed plate obtained is rolled at a temperature of 150 to 380 C. A piece of silver chloride with a predetermined shape is punched out of the rolled plate with the aid of a press. ' _N

Another embodiment of the production method according to the invention will now be explained with reference to FIG. 3. In FIG. 3 there is a molten silver salt bath 2 in a bath cell 1 which contains a melt of a silver salt from the group consisting of silver chloride, silver bromide and silver iodide (silver salts which are sparingly soluble in water). Part of a rotor 3 cooled with cold water or a cooling medium h is immersed in the molten bath 2. With the aid of the peeling device 5, the silver salt adhering to the circumference of the rotor or the rotating drum 3 is scraped off. The rotor 3 is solidified silver salt 6 ₀ The by means of the peeling device 5 scraped thick plate 7 made of silver salt is rolled with auxiliary © of the rollers 8 to a thin plate 9, from which punched out by means of · a press silver chloride pieces.

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According to a further embodiment of the invention Commercial silver chloride powders are first molded to an appropriate size. At this stage, excess, chlorine adsorbed on the surface of the silver chloride cannot be removed. The formed silver chloride is therefore used to remove the excess chlorine and final shaping with the aid of hot rollers a temperature below the melting point of silver chloride (455 ° C), for example at 400 C, hot-rolled. The excess chlorine is used in this heat treatment. stage split off and removed. A rolled, silver chloride plate freed from excess chlorine. At this stage one perceives a smell of chlorine, which indicates its escape. The silver chloride plate is punched into a predetermined shape using a press, with a thinly rolled-out piece of silver chloride is obtained.

The piece of silver chloride obtained by the methods described above does not contain excess chlorine. An excellent correlation between the surface of this piece and the amount of leached silver ions is therefore achieved. Fig. 2 shows the relationship between the surface area of this piece of silver chloride (the surface of the thickness dimension was not taken into account) and the leached silver ion content when the piece was immersed in water at 30 ° C. for Zh hours. It can be seen from FIG. 2 that the proportion of silver ions dissolved out increases proportionally with the surface area of the piece of silver chloride. When using such a piece of silver chloride, the desired solubility can thus be achieved by specifying the surface area or the weight of the piece. This is of great advantage in setting a solubility as minimal as about 50 / µg / liter (θ, 000005 #; 50 ppb).

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Because you get the silver chloride in the form of a thin piece can use, there is also not even then the risk of powder passing through a powder Filter cloth if it is introduced into the water inlet of a water purifier. This application form is therefore preferred to prevent chemical contamination. Such a use of silver chloride in the form of a thin piece is also in quality control which as part of the monitoring of the water purifier loading is made, more advantageous than the use in powder form «

The following are the results of testing the silver chloride prepared according to the present invention with respect to its bactericidal effect shown »

example 1

Pressed silver chloride is rolled into a plate with a thickness of 0.5 mm and cut into panels with a surface area of 20, kO or 100 cm .. The panels are tested for their bactericidal effect. 1 liter of H_0, which has a content of

' 8th

Escherichia CoIi K-12-A of about 8 10 / ml. Each of the silver chloride pieces mentioned is immersed in the test water at 30 ° C. The bacteria count is below Use of DHL agar culture medium obtained. The results can be seen from Table I.

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Table I.

Surface of the
Silver chloride
piece, cm Beginning 0 20th 40 100 number
the
Bacteria
rien / ml after
20 min 8 χ 10® 8 χ 10® 8 χ 10® 8 χ 10® after
6o min 5 x 10® 7 χ Ip ⁷ 0 0 2 χ 10® 0 0 0

The test water is pure water (Cl ~ = θ).

The results presented in Table I show that

2 a piece of silver chloride with a surface of about 20 cm

to kill about 8 χ 10 / ml Escherichia CoIi K-12-A in a water purifier with a capacity of 1 liter was sufficient. In this example, silver chloride is used. One can however, use silver iodide analogously, its melting point however 552 ° C and its water solubility 10 ~ mol / liter. Silver bromide can also be found in the same Use wise.

Example 2

Commercially available silver chloride powder is first formed into a plate, which is then hot-rolled at 400.degree. A sheet (5 × 5 cm; about 2 g) is punched out of the hot-rolled plate and used as a bactericide. The test water used is 1 liter of water with an Escherichia CoIi K-12-A content of 3 × 10 ⁹ / ml. In this test water, 0.003 # (30 ppm) chlorine ions are added.

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against be. One dips the aforementioned silver chloride table into the test water, the results shown in Table II being obtained.

Table II

Immersion time, hours 2 6th 8th 10 15th ^20th Proportion of the living
Bacteria, $ 95 90 80 50 10 0

The results given in Table II show that that a piece of silver chloride with a surface

2 9 /

25 cm is sufficient, about 3 * 1.0 / ml Escherichia CoIi K-12-A in a water purifier with a content of 1 liter, which is for tap water with a chlorine content of about $ 0.003 (about 30 ppm) chlorine is intended to kill. If the thickness of the silver chloride piece is further reduced, the amount by weight to be used can be determined reduce in silver chloride ..

Example 3

The bactericidal effect of a silver chloride plate according to the present invention against "conventional" bacteria is shown with reference to the relation between the surface of the plate and the number of bacteria tested for different treatment durations. "Conventional" bacteria are those bacteria

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Table III

Size of in a)
b) 8th
8th 1 *) 8th
8th 2 10 «
10 « co oo 3 10 «
10 ⁸ 8th
8th 1 4th 0 «
0 « 8th
8th 5 10 «
10 « 00 00 1 6th oo oo 1 7th • oo co 8th 10 «
10 « AgCl (Ge cra ^ / liter) a) 5 O I. 3 20th 10 « 1 40 10 ⁷ 7th 00 o ⁶ 4th 500 10 ⁵ _k 000 5 500 7th 2000 10 ² velvet top Beginning b) 8th 7th 10 « 7th 10 ⁵ 8th o ⁶ 1 10 ⁶ 8th 4th ₁₀ 3 area after X
X X
X X
X 20 min a) 2 X
X 10 «
10 « 8th X
X 10 ⁵ 2 X
X 10 ⁵ 3 X 1
1 <> * ■ 5 X
X 10 ³ 1 X 10 «
10 « 8th X 10 «
10 « X
X b) 8th X 10 « 6th X 10 « 8th X 10 ⁶ 7th X 1 o ⁶ 3 X 10 ⁵ 4th X 10 * 6th X 10 ³ 3 X 10 after X 10 « X X 1 X 10 * 10 ³ X 1 H. a) k 1 10 ³ 2 10 ² 6th X 0 * 3 10 ² 1 X X Number b) 6th X 10 ⁵ k X 10 ⁷ 3 X 10 ⁶ 2 X 1 O ³ 9 X 10 ² 5 X 10 ³ 3 X 10 0 tr
H after X 10 « X X 1 X 10 ³ 10 ² X O. 5 hours a) X X 0 φ b) 5 X 10 ² k X 10 ⁶ 1 X 10 * 6th X 1 o ² 1 X 10 X 10 X 0 bd
• r ¹ after a) X 10 « X X 1 X 10 10 0 el 8 hours b) 1 8th 10 ² 7th 10 ² 0 0 0 Φ
H after a) O 0 0 X 0 0 0 0 ien, 16 hours b) 1 X 10 « 3 X 10 X 0 1 X 0 0 0 ■ «
H after O 0 0 0 0 0
0 0 0 24 hours X 10 ⁷ X X 0 0 0 0 0 O 0 0 0 0 0 0 0 X 10 ⁷ X 0 0 0

*) Blank test water (a) s no Cl "(pure water)

Test water (b): Cl "" = 0.003% (30 ppm) (tap water from which the bleaching powder removed).

VJ I

ro

CD cn co cn

The above examples show that a silver salt

2 'plate with a total surface area of 20 to 2000 cm / liter

has an excellent bactericidal effect «

It can be silver chloride, bromide or iodide ₉ further enforce other substances as extenders "

Although Ag ions can be leached out in a constant amount per surface unity, if in stoichiometric terms Ag ^ halogen, difficulties arise when the halogen is present in excess »

TJm a silver salt bactericide with Ag> · halogen to produce • you can therefore use a powdery silver salt heat a temperature close to its melting point, getting the same effect as by. Heating the silver salt to a temperature higher than its melting point. Another method is to bring a silver salt into a certain shape and heat the formed product a temperature close to its melting point <> One can also apply a silver salt by vacuum evaporation on a support or deposit on a carrier in order to achieve that Ag> ■ Cl is. This vacuum evaporation method also includes a melting step in the evaporation of the silver salt ο

According to the above examples, Süberchio = rid is used. But it is also silver (melting point = 434 ° C) and silver iodide (melting point 552 ⁰ C) analog use.

The solubility of silver chloride in tap drums generally depends on the chlorine ion concentration in question

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centering off. When treating tap water one high chlorine ion concentration can therefore only achieve the silver solubility required for sterilization when increasing the surface area of the piece of silver chloride. However, if you have groundwater or water with a Chlorine ion concentration less than $ 0.0005 (^ 5 ppm) wants to treat, the silver ion concentration exceeds even when using a silver chloride tablet with a Surface area of 1 cm has a value of 0.000005 # (50 ppb) (water quality standard in the V. St. A.) if you take the immersed the mentioned board or the piece in the water for more than 3 days. In such a case, therefore, there is a piece of silver chloride not suitable. You can then use silver bromide or iodide, whose solubility is lower is (10 or 10 ~ mol / liter), sterilize water free of chlorine ions.

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Claims (8)

Claims ■ 1. Process for the preparation of a fiactericide for the water treatment, which means that it is not possible to that the excess, the stoichiometric Exceeding proportion of halogen from a silver salt from which Group silver chloride, silver bromide and silver iodide removed. ' 2, method according to claim 1, characterized in, that you can use the silver salt to remove the excess Halogen heats and melts. 3- The method according to claim 1, characterized in, that one powder from the silver salt for cleavage and removal of the excess adsorbed halogen is heated and the melt forms or presses * 4. The method according to claim 1, characterized in that that one powder from the silver salt into a thin plate processed with predetermined shape and the molded product thermally treated to remove the excess halogen adsorbed on the silver salt. 5. The method according to claim 1, characterized in that that one melts the silver salt, part of a cooled rotor to produce a thin film of the silver salt immersed in the molten silver salt on the rotor surface, peeled off the thin film from the rotor and through continuous Rolling of the film with the help of a rolling device 1Ϊ4 8 device continuously, a thin plate with the given Creates strength. 6. The method according to claim. 1, characterized in that the silver salt by vacuum evaporation on a Underlay is deposited, which does not react with the silver salt. 7. Process for treating water with the aid of the bactericide prepared according to the process of claims 1 to 6. 8. The method according to claim 7 »characterized in that the bactericide used has a total surface area of 20 to 2000 cm ² / liter. 9 use of a silver salt from the group silver chloride, Silver brpmide and silver iodide, of which the excess halogen exceeding the stoichiometric proportion has been removed and which has a total surface area of 20 to 2000 cm / liter, for water treatment. 3098 33/1148 Blank.page