SU1031901A1 - Method for preparing silica gel - Google Patents

Description

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The invention relates to the synthesis of inorganic sorbents and can be used in folklore to produce catalyst supports, adsorbents for chromatography, for optical glassmaking, etc.

A known method of producing silica gel by precipitation of a hydrogel of silicic acid with its further washing is first acidified and then ammonia water under vacuum f 1 J.

The drawbacks of the method are the large penetration fluid discharges, in addition, special filtering equipment and instruments are used in the process of the process.

The closest in technical essence and the achieved result to the proposed method is a method of obtaining silica gel, which precipitates the hydrogel, aging, drying at 450 ° C and spilling industrial water for 5 hours 2 J.

However flushing; A xeroglu only with water cannot provide a high degree of purity of the product on sodium ions (less than 0.1 weight,%), and drying a hydrogel / containing many alkaline cations, at high temperature leads to sintering of the pores which complicates washing and affects the porous structure of silica gel. .

The purpose of the invention is to increase the purity of the product with a single-flow rate of the washing liquid, as well as to obtain silica gel in hydrogen form or modified with metal ions.

This goal is achieved by the method of obtaining silica gel, including precipitation of a hydrogel, aging, drying to the state of xerogl at a temperature not higher than ISp C, ion exchange with a solution of an acid or a metal salt to a constant concentration of the exchanging ion in the output solution and washing with water.

Moreover, as a chemical reagent, an acid solution or a salt solution of the corresponding metal is used.

The essence of the proposed cnoco6ai is as follows.

The silicic acid hydrogel obtained by precipitation from alkaline silica solids with mineral or organic acids is dried together with the mother liquor by any known method.

The resulting xerogel containing. 5 salt, crushed, loaded into an ion exchange column and then subjected to treatment with a chemical reagent. The xerogel treatment with a chemical reagent allows an increase in the purity of the product while simultaneously reducing the flow rate of the npoi iB liquid. The acid treatment is carried out if it is necessary to obtain the hydrogen form, and the salt of the corresponding synthetic methadia is treated for

obtain metal ion modified silica gel.

After this treatment, the product is washed with distilled water.

The drying temperature should not be exceeded, since with increasing temperature, it is possible to sinter the pores of the silica gel and deteriorate its structure and decrease purity.

The total amount of washing liquid, calculated per kilogram of dry silica gel, depends on the conditions for obtaining the hydrogel and does not exceed 30 liters, while the content of alkali metal ions in the final

0 product does not exceed 2-10, wt.%, Which is at least. Order of magnitude higher than in the prototype.

The amount of exchangeable sodium ions on the surface of the xerogel is controlled by the conditions of the deposition of the hydroreate, as well as by washing the xerogel with water before treatment with the metal salt.

Example 1. 11.2 g of an alkaline silica solution containing 8.9% SiOj are neutralized with a solution of nitric acid to pH of the medium 3. After-. radiated hydrogel after aging / for 4 hours while dried at 150 ° C to constant weight. A dried crushed xerogel in the amount of 1.6 kg was loaded into an ion-exchange column and treated with 5% nitric acid until the concentration of sodium ions in the

0 output solution of IlO g / l, and then rinse with distilled water.

The consumption of the washing liquid and the results of lipoMfciBKH are given in table 1. Table 1

Example 2. 7.5 liters of alkaline. A silica solution containing 13.5% Si02 is neutralized with a solution of tartaric acid to pH 5.5. The resulting hydrogel after aging. for 4 hours at SOe, dried at llO to constant weight. A dried crushed xerogel in the amount of 1.6 kg was loaded into an ion exchange column and treated with nitric acid until the end of sodium ions in the output solution was reduced to 1 –io g / l, and then washed with distilled water.

P and measures 3. 9.5 l of menoHHo-silicon-e1 “clear solution containing 13.5% of SiOlj, nvayt {sludge with a solution of sulfosalidyl acid to a pH of 10.5. “get loaded into the ibn exchange column, treated with 5% sulfuric acid solution

acid, and then washing with distilled water.

The flow rate of the washing liquid and the results of the washing are given in Table 1.

EXAMPLE 4 Xerogel, prepared in Example 1, was loaded onto a column of exchange, washed with water and 0.5 m of solution, the sun of co-dT yICN of its metal until a constant concentration of metal salt was reached in the solution, and then washed with distilled water,

 Example 5. The xerogel, of the half-length & OfsiMepy 2t is loaded into the ion column COLONKUU then act aeajqorK4 “about example 4.

Example 6. The xerogel obtained prior to example 3 is loaded into the ionization system in a column | g followed by actions: years and & 4.

Fluid consumption and modification results are given in Table. 2

, Table 2

The number of ions per regulated is 1; 1 after the drying.

Before the 11th session, the production of a lecagel as compared to the well-known tehnologies of the production of a cynicagel due to the possibility of filtration and the application of a hydrogel that require specimen

successful, noBtxiiaeT degree of pure. product with one of the costs of water, in addition, learn about the value of the modalist ion by the rap metal ions. tallov.

Claims (2)

2. Copyright certificate of the USSR ”201349, cl. С 01В 33/16, 1967. 1 1. METHOD FOR PRODUCING SILICAGEL, including precipitation of hydrogel, aging, drying to a xerogel state and rinsing with water, so as to “increase” the purity of the product while reducing the flow rate of the washing liquid, drying is carried out at a temperature not exceeding 150 ° C, and the dried xerogel is subjected to ion exchange with a solution of a chemical reagent before rinsing water to a constant concentration of the exchange agent. ion in the output solution. 2. The method of iro n. 1, due to the fact that, for the sake of "obtaining the hydrogen form of the silicate · an acid solution is used as a chemical reagent." 3. The method according to π. 1, which is related to the fact that, in order to obtain silica gel modified by metal ions, a salt solution of the corresponding metal is used as a chemical reagent. .