RU2247073C2 - Method for production of ammonium tetrachlorocuprate(ii) dihydrate - Google Patents

Abstract

FIELD: chemical technology.

SUBSTANCE: ammonium tetrachlorocuprate(ii) dihydrate is obtained by crystallization from aqueous solution with pH 0.0-5.0, produced by addition of 15-30 mass % ammonia solution or 15-40 mass % hydrochloric acid solution to spent solution from printing plate etching, containing copper(II) chloride, ammonium salt, and hydrochloric acid or ammonia.

EFFECT: method of reduced cost; utilization of toxic waste from radio and electronic industry.

4 cl, 4 ex

Description

The invention relates to the field of chemical technology, in particular to a method for producing ammonium tetrachlorocuprate (II) dihydrate (NHO ₄ ) ₂ CuCl ₄ · 2H ₂ O, which can be used for antibacterial treatment of water, as a fungicide and copper microfertilizer in agriculture, for preparing a solution for etching printed circuit boards to obtain anhydrous ammonium tetrachlorocuprate (II), copper (I) and copper (II) chlorides, copper (II) hydroxochloride and other copper compounds.

It is known that from aqueous solutions containing copper (II) chloride and ammonium chloride, ammonium tetrachlorocuprate (II) dihydrate of the composition (NH ₄ ) ₂ CuCl ₄ · 2H ₂ O crystallizes [1-3].

A known method of producing dihydrate of tetrachlorocuprate (II) ammonium by crystallization by slow evaporation of an aqueous solution containing copper (II) chloride and ammonium chloride in a molar ratio of 1: 2 [4]. The disadvantage of this method is the length of the process and the need for additional costs for the reagent - copper (II) chloride.

Closest to the alleged invention is a method for producing ammonium tetrachlorocuprate (II) dihydrate, comprising preparing a reaction solution containing copper (II), chloride and ammonium, crystallizing the product at room temperature, separating the crystals from the solution and drying them [5]. The reaction solution is prepared by adding an aqueous solution of ammonium chloride to an aqueous solution of copper (II) chloride by heating, followed by concentration of the solution by heating it in a water bath. The method allows to obtain pure dihydrate of tetrachlorocuprate (II) ammonium in high yield. The disadvantage of this method is the need for additional costs for heating the reaction solution and for the reagent copper chloride (II).

When creating the invention, the task was to reduce the material costs of obtaining tetrachlorocuprate (II) ammonium dihydrate and to utilize toxic waste products in order to protect the environment.

This is achieved by the fact that the method of producing ammonium tetrachlorocuprate dihydrate (II) involves preparing a reaction solution containing copper (II), chloride and ammonium, crystallizing the product, separating the crystals from the solution, and drying them. New in this method is that the reaction solution is prepared by adding the reagent to the spent etching solution of the printed circuit boards to a pH of from 0.0 to 5.0, with hydrochloric acid with a mass fraction of hydrogen chloride from 15 to 40% being used as the reagent. PCB etching solution contains copper (II) chloride, ammonia, ammonium chloride or copper (II) chloride, ammonia, ammonium chloride, ammonium carbonates or aqueous ammonia with a mass fraction of ammonia from 15 to 30% is used as a reagent, and the spent solution etching seal s cards comprises copper chloride (II), hydrochloric acid or copper chloride (II), hydrochloric acid, ammonium chloride. As a reagent, it is desirable to use hydrochloric acid with a mass fraction of hydrogen chloride from 20 to 40% or an ammonia solution with a mass fraction of ammonia from 20 to 30%. Crystallization of the product is preferably carried out at a temperature of from -5 to 30 ° C.

A method of producing ammonium tetrachlorocuprate (II) dihydrate is to prepare a reaction solution by adding hydrochloric acid to the spent alkaline copper-ammonia solution to etch printed circuit boards or by adding ammonia to the acid-coated copper-chloride solution to etch the printed circuit boards, and isolating the dihydrate ammonium tetrachlorocuprate (II) in the form of a crystalline precipitate at a certain temperature, separation of the precipitate from the solution by known methods, washed and (if necessary) precipitate with a solvent, drying the precipitate in air.

The spent solutions for the etching of printed circuit boards (copper-alkaline based on copper (II) chloride, ammonium carbonates, ammonium chloride, ammonia; acidic solutions based on copper (II) chloride, ammonium chloride, hydrochloric acid) are toxic waste from electronic production and must be rendered harmless , which requires the costs of their neutralization [6,7]. Hydrochloric acid GOST 3118-77 and ammonia solution GOST 3760-79 are produced by the chemical industry and have a low cost. When these reagents are added to the spent etching solutions of the printed circuit boards, the following chemical reactions proceed:

As a result, crystalline ammonium tetrachlorocuprate (II) dihydrate is isolated from the solution. The proposed method allows to obtain ammonium tetrachlorocuprate (II) dihydrate using available and inexpensive reagents - hydrochloric acid or ammonia solution and at the same time to utilize the waste of electronic production - the spent solution of etching printed circuit boards.

To obtain ammonium tetrachlorocuprate (II) dihydrate, spent PCB etching solutions containing copper (II), ammonia, ammonium chloride, ammonium carbonate, and hydrochloric acid must be used. Used printed circuit board etching solutions containing peroxodisulfates, sulfates or sulfuric acid cannot be used, since ammonium tetrachlorocuprate (II) dihydrate is not released when treating such solutions with hydrochloric acid or ammonia. Also, do not use spent etching solutions for printed circuit boards based on iron (III) chloride or chromic anhydride, since ammonium tetrachlorocuprate (II) dihydrate released during the processing of such solutions is contaminated with an admixture of iron or chromium compounds.

Ammonium tetrachlorocuprate (II) dihydrate is a crystalline substance of a bright blue color, readily soluble in water, slightly soluble in ethyl alcohol, acetone, poorly soluble in acetic acid, carbon tetrachloride, benzene.

Ammonium tetrachlorocuprate (II) dihydrate crystallizes well from aqueous solutions, the precipitate easily settles without forming colloidal particles, therefore, many known methods can be used to separate it from the solution, for example, centrifugation, filtration under ordinary or reduced pressure.

During filtration, the precipitate is easily separated from the mother liquor. If necessary, more complete removal of substances present in the mother liquor, the precipitate is washed on the filter with a suitable solvent, for example methanol, ethanol, acetone.

Since ammonium tetrachlorocuprate (II) dihydrate is readily soluble in water [8], to obtain it in high yield, excessive dilution of the spent etching solution of the printed circuit boards should be avoided. Therefore, it is necessary to use ammonia and hydrochloric acid solutions with concentrations of at least 15% as reagents. The upper limits of concentrations of 30 and 40% are limited by the solubility of these substances in water.

The solubility of ammonium tetrachlorocuprate (II) dihydrate in water is little dependent on the pH of the solution. However, when crystallizing the product from strongly acidic solutions, additional washing of the filter cake is required, which reduces the yield of the product. If the pH of the solution is above 5.0, the product may be contaminated with water-insoluble copper (II) hydroxochlorides or copper (II) hydroxide. Therefore, to obtain pure ammonium tetrachlorocuprate (II) dihydrate, it is necessary to prepare a reaction solution with a pH of from 0.0 to 5.0.

The solubility of ammonium tetrachlorocuprate (II) dihydrate in water increases significantly with increasing solution temperature [8]; therefore, to increase the yield of the product, it is desirable to crystallize at a temperature of from -5 to 30 ° С.

Example 1

4.5 ml of concentrated hydrochloric acid are added to 10 ml of the spent solution for etching printed circuit boards with a copper (II) concentration of 1.09 mol / L, ammonium chloride 0.30 mol / L, ammonia 4.4 mol / L, with stirring. After 2 days, the precipitate is squeezed out on a paper filter and dried in air at room temperature to constant weight. Yield 21%.

Found,%: Cu - 22.9; N - 10.0; Cl - 50.9.

Calculated for (NH ₄ ) ₂ CuCl ₄ · 2H ₂ O,%: Сu - 22.90; N, 10.10; Cl - 51.11.

Example 2

To 10.0 ml of spent etching solution for printed circuit boards with a copper (II) concentration of 1.53 mol / L, ammonium chloride 0.12 mol / L, ammonium carbonate 3.67 mol / L, ammonia 3.05 mol / L with stirring concentrated portions of hydrochloric acid are added in portions until a pH of 0.5 is reached. The solution was allowed to crystallize for 1 day at a temperature of 0 ° C. The precipitate was filtered off on a POR 100 glass filter under reduced pressure, washed with ethanol and dried in air at room temperature to constant weight. Yield 79%.

Found,%: Cu - 22.7; N, 10.1; Cl, 51.4.

Example 3

To 10 ml of the spent solution for etching printed circuit boards with a copper (II) concentration of 1.70 mol / L, ammonium chloride 2.0 mol / L, and 0.3 mol / L hydrogen chloride, 2.0 ml of concentrated hydrochloric acid is added first, then dropwise with stirring, a 25% ammonia solution until a pH of 2.5 is reached. The solution is left to crystallize for 2 days at a temperature of 5 ° C. The precipitate is squeezed out on a paper filter and dried in air at room temperature to constant weight. Yield 38%.

Found,%: Cu - 22.7; N - 9.9; Cl - 51.3.

Example 4

To 10.0 ml of the spent etching solution for printed circuit boards with a copper (II) concentration of 2.35 mol / L, 5.5 mol / L hydrogen chloride, a 25% ammonia solution is added dropwise with stirring until a pH of 3.1 is reached. The solution is allowed to crystallize for 2 days at a temperature of -1 ° C. The precipitate is filtered off on a POR 100 glass filter under reduced pressure, washed with acetone and dried in air at room temperature to constant weight. Yield 42%.

Found,%: Cu - 22.8; N - 10.0; Cl - 50.8.

As can be seen from the above examples, the claimed method allows to obtain with a high yield of ammonium tetrachlorocuprate (II) dihydrate, exactly corresponding to the chemical formula (NH ₄ ) ₂ CuCl ₄ · 2H ₂ O. The material cost reduction for obtaining the product is achieved due to the fact that as instead of copper (II) chloride, one of the reagents uses copper-containing spent solutions for etching printed circuit boards of various compositions. Simultaneously with obtaining a useful product, it is possible to utilize the toxic waste of electronic production, to reduce environmental costs.

Used sources

1. Rivett A.C.D., Clendinnen F.W. J. // Joumal of Chemical Society, 1923, V.123, P.1634.

2. Hendricks S. B., Dickinson R. G. // Journal of the American Chemical Society, 1927, V. 49, P. 2149.

3. Skripkin M.Yu., Chernykh L.V. // Journal of Inorganic Chemistry, 1994, T. 39, No. 10, S. 1747.

Kristallographie, 1934, Bd. 88, S. 35.4. Chrobak L. // Zeitschrift

Kristallographie, 1934, Bd. 88, S. 35.

5. Lesnova EV Workshop on inorganic chemistry. Ed. 2nd. -M .: Higher school, 1977, S. 138.

6. Flerov V.N. Chemical technology in the production of electronic components. -M .: Radio and communications, 1988, S. 47.

7. Fedulova A.A., Ustinov Yu.A., Kotov E.P., Shustov V.P., Yavich E.R. Technology of multilayer printed circuit boards. -M .: Radio and communications, 1990, p.186.

8. Handbook of solubility. T. 1. Book 1. - M.-L .: Iz-in AN SSSR, 1961, S. 188.

Claims (4)

1. A method of producing ammonium tetrachlorocuprate (II) dihydrate, which includes preparing a reaction solution containing copper (II), chloride and ammonium, crystallizing the product, separating crystals from the solution and drying them, characterized in that the reaction solution is prepared by adding the reagent to the spent solution etching of printed circuit boards to a pH of from 0.0 to 5.0, moreover, hydrochloric acid with a mass fraction of hydrogen chloride from 15 to 40% is used as a reagent, and the spent solution of etching of printed circuit boards contains copper (II) chloride, ammonia, chl ammonium or copper (II) chloride, ammonia, ammonium chloride, ammonium carbonates or an aqueous ammonia solution with a mass fraction of ammonia from 15 to 30% is used as a reagent, and the spent solution for etching the circuit boards contains copper (II) chloride, hydrochloric acid or copper (II) chloride, hydrochloric acid, ammonium chloride. 2. The method according to claim 1, characterized in that the hydrochloric acid with a mass fraction of hydrogen chloride from 20 to 40% is used as a reagent. 3. The method according to claim 1, characterized in that the reagent is an ammonia solution with a mass fraction of ammonia from 20 to 30%. 4. The method according to claim 1, characterized in that the crystallization of the product is carried out at a temperature of from -5 to 30 ° C.