JP2592712B2 - Method for producing sterilizing purifying agent - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a purifying agent for sterilization, and more particularly, to a method for producing a purifying agent for sterilization which is useful as a material for drinking water by coating the surface of coral sand with silver. It is about the method.

(Prior Art) It is already well known that a substance obtained by attaching silver to the surface of a base material such as activated carbon, pumice stone, coral sand or the like is used as a disinfectant for water treatment.

However, in this production method, silver nitrate is dissolved in aqueous ammonia to form a silver-ammonia complex, a base material is immersed in the solution, a reducing solution such as formalin or glucose is added to the solution, and the silver is converted into a base material by this reaction. It is widely used to make a precipitate by so-called silver mirror reaction.

(Problems to be Solved by the Invention) However, in the case of this silver mirror reaction method, the operation is complicated and various reagents are required, and in this case, it is necessary to consider the treatment of organic wastewater. Disadvantage.

For this reason, the present inventor added a silver nitrate solution to the coral sand earlier to make the surface covered with silver carbonate, and then added hydrogen peroxide to this to reduce it to silver carbonate, A method for obtaining coral sand having silver adhered to the surface was proposed (see Japanese Patent Publication No. 34228/1988). According to this method, it was confirmed that the intended purifying agent for sterilization could be obtained very easily. This requires the addition of aqueous hydrogen peroxide, which has the disadvantage of being industrially expensive.

(Means for Solving the Problems) The present invention relates to a method for producing a sterilizing purifying agent which solves such disadvantages, which comprises adding a silver nitrate powder or an aqueous solution to coral sand, mixing the resulting mixture, and placing the mixture at 210 to 250 ° C. The silver carbonate is generated by the reaction between the molten silver nitrate and the calcium carbonate of the coral sand, and then heated to 250 to 350 ° C. to accelerate the thermal decomposition of the silver carbonate. Characterized in that they are deposited on

That is, the present inventor conducted various studies on a method for producing a sterilizing purifying agent at low cost using naturally produced coral sand as a base material, and found that the coral sand was mainly composed of calcium carbonate. Therefore, if silver nitrate is applied to this, the surface will be covered with silver carbonate,
In order to reduce this silver carbonate to silver, it is easily thermally decomposed, so if it is heated to 250-350 ° C, it is thermally decomposed and silver is easily deposited on the coral sand surface Therefore, the present inventors have found that the intended purifying agent for sterilization can be obtained very easily, and in this case, it has been confirmed that an industrial advantage that no reaction residue remains at all is provided. Was completed.

 This will be described in more detail below.

(Action) In the method of the present invention, first, coral stone is reacted with silver nitrate. This is performed by collecting coral sand in a container, adding a silver nitrate powder or an aqueous solution thereto, mixing the mixture, and then heating the mixture to 200 to 250 ° C. It may be heated to. When the mixture of coral sand and silver nitrate is heated, silver nitrate is easily melted because the melting point is 210 ° C. However, since the coral sand is mainly composed of calcium carbonate, this silver nitrate is It reacts by the formula AgNO ₃ + CaCO ₃ → Ag ₂ CO ₃ + Ca (NO ₃ ) ₂ to form silver carbonate and adhere to coral sand. The silver nitrate added here may be in the form of powder, but depending on the particle size and the mixing ratio, the attachment of silver may be non-uniform, and the recovery rate may be reduced. Is impregnated into coral sand as an aqueous solution, silver attachment becomes uniform, the recovery rate is improved, and it is possible to cope with fluctuations in conditions such as particle size and mixing ratio.
The amount of silver added was as follows. Coral sand as a sterilizing agent was coated with silver, but the optimal amount of silver was 0.15 to 1 with respect to coral sand.
%, The amount of silver carbonate corresponding to the amount of silver may be determined. Therefore, the amount may be in the range of 0.23 to 1.6 parts by weight of silver nitrate per 100 parts by weight of coral sand.

The silver carbonate-coated coral sand thus obtained is then deposited on the coral sand as silver by the thermal decomposition of silver carbonate. When the coral sand covered with the silver carbonate is heated to 250 to 350 ° C., the silver carbonate is thermally decomposed and the generated silver is deposited on the surface of the coral sand.

This reaction reduces silver carbonate to obtain silver-coated coral sand, which can be obtained as containing no impurities by washing with water and removing the calcium nitrate present in the system with water. So then dehydrate it
Drying at 100 to 300 ° C, especially at 150 to 200 ° C for 1 to 2 hours can easily obtain the intended purifying agent for sterilization. In this case, silver nitrate becomes silver carbonate by reaction with calcium carbonate. However, this thermal decomposition turns into silver, and the recovery rate of silver becomes 90% or more. Therefore, this impregnation rate is improved as compared with the conventional method, and the amount of impregnation to coral sand is also accurately determined by the amount of silver nitrate added first. The industrial advantage of being adjustable is provided.

In short, in the method of the present invention, silver nitrate powder or an aqueous solution is added to coral sand containing calcium carbonate as a main component, mixed and then heated to melt silver nitrate, which is reacted with silver calcium carbonate and coated with silver carbonate. With coral sand
Then, the silver carbonate is thermally decomposed to deposit silver on the coral sand. According to this, the reaction is CaCO ₃ + AgNO ₃ → Ag ₂ CO ₃ + Ca (NO ₃ ) ₂ , Ag ₂ CO ₃ → Ag + CO ₂ Calcium nitrate as a reaction residue that proceeds in a clean reaction of {+ O ₂ } can be easily removed by subsequent washing with water, and no post-reaction treatment is required. The intended purifying agent for sterilization can be obtained at low cost, and according to this, it is possible to improve the silver impregnation rate as described above and to provide the advantage that the silver impregnation rate can be accurately adjusted. Can be

(Example) Next, an example of the method of the present invention will be described.

Example 1 1 kg of coral sand (coral sand) was collected, and 100 g of the coral sand was thinly spread on the bottom of the calcined boat to prevent silver nitrate having melted from flowing to the bottom of the boat and escaping. 17 g of silver nitrate powder was mixed, 300 g of coral sand was added and mixed, and the remaining
After adding 500 g of coral sand, they were mixed well by mixing well, and this was filled into a firing boat at an average thickness.

Then, when this was heated to 210 to 250 ° C. for 30 minutes, silver nitrate melted and reacted with calcium carbonate to form silver carbonate,
The surface of the coral sand was coated with this silver carbonate.

Next, the temperature in the furnace was raised to 250 to 350 ° C. and calcined at this temperature for 1 hour. The silver carbonate was thermally decomposed, and the generated silver was deposited on the surface of the coral sand. After washing and removing calcium nitrate mixed in,
After dehydration and drying at 150 to 200 ° C. for 1 hour, a sterilizing purifying agent having silver deposited on the coral sand surface was obtained. When this experiment was repeated five times, the amount of silver impregnated was as follows.
As shown in the table, the recovery rate of silver was
90% or more.

Example 2 1k of coral sand (coral sand) in a deep stainless steel container
g was collected, and a solution prepared by dissolving 17 g of silver nitrate in 100 ml of water was poured to uniformly infiltrate the mixture.Then, the mixture was heated to 210 to 250 ° C. for about 1 hour. became.

Then, the temperature was raised to 250 to 350 ° C., and the mixture was calcined at this temperature for about 1 hour. As a result, silver generated by thermal decomposition of silver carbonate was uniformly deposited on the surface of coral sand. After washing this with water, 15
After heating and drying at 0 to 200 ° C. for about 1 hour, the desired sterilizing agent for sterilization was obtained.

The amount of silver impregnated is as shown in Table 2, and this one was particularly excellent in silver recovery and silver adhesion uniformity.

The sterilizing agent thus obtained was placed in a beaker, water was added, and the mixture was stirred, but the water was transparent and no silver was peeled off. In a 300 ml beaker, add 50 g of this sterilizing purifying agent (test product) and 100 ml of water containing aquatic bacteria containing 61,000 aquatic bacteria / ml, mix well, and stir. When the number of bacteria was measured by watering, the results as shown in Table 3 were obtained.

Although the intended sterilizing agent can be obtained by either of the methods of Examples 1 and 2, the purpose of Example 1 is to simplify the process rather than the recovery rate of silver and the uniformity of adhesion. The method of Example 2 focuses on high recovery and product uniformity through a stable process. In each case, the amount of silver eluted was 50 ppb or less, and as shown in Table 3, not only sufficient sterilizing action was exhibited, but also
There is no concern about the stability limit of Ag ions due to the below 50 ppb, that is, the safety to the human body.

(Effect of the Invention) The present invention relates to a method for producing a purifying agent for sterilization. As described above, silver nitrate powder or an aqueous solution is added to coral sand, mixed, and then heated to 210 to 250 ° C. to melt. The resulting silver nitrate is reacted with calcium carbonate to form silver carbonate, which is then heated to 250 to 350 ° C. to thermally decompose the silver carbonate and deposit the generated silver on the coral sand surface. The desired sterilizing agent can be obtained simply by adding silver nitrate to coral sand and heating, so that the intended sterilizing agent can be obtained very easily and economically more advantageously than the conventional method. The industrial benefit of being able to do so is provided.

Claims (2)

(57) [Claims] After adding silver nitrate powder or an aqueous solution to coral sand and mixing the mixture, the mixture is heated to 210 to 250 ° C. to react the molten silver nitrate with the calcium carbonate of the coral sand to form silver carbonate. A method for producing a sterilizing agent, comprising heating to 350 ° C. to accelerate the thermal decomposition of silver carbonate and depositing the generated silver on the surface of coral sand. 2. The coral sand on which silver has been deposited is washed with water and dehydrated.
The method for producing a sterilizing agent according to claim 1, wherein the agent is dried.