亚硫酸钠从含银废液中还原银的研究

Study on Reduction of Silver with Sodium Sulfite from Silver-containing Liquid Waste

利用配位化学理论,研究了溶液中游离亚硫酸根离子浓度、pH值、亚硫酸钠浓度对亚硫酸钠还原银的影响。结果表明:亚硫酸银的溶解度[Ag]T与游离亚硫酸根离子浓度[SO32-]呈非线性函数关系;在2(pH(8时,亚硫酸银的溶解度随着pH的减小而减小,在pH(2时,亚硫酸银的溶解度随着pH的减小而增大,得出亚硫酸银最佳析出的pH=2;在最佳析出条件下,亚硫酸银的溶解度随着亚硫酸钠浓度的减小而减小。同时从热力学角度验证了在pH=2时,亚硫酸银能够被还原成银,并且还原程度较高。从而得出pH=2是亚硫酸钠从溶液中还原银的最佳条件。最后结合工业生产,验证了理论分析的正确性。

In this paper, the influences of the pH value, the concentrations of free sulfite ions and of sodium sulfite on reduction of silver by sodium sulfite were studied based on the complex chemistry theory. The results show that the solubility of silver sulfite [Ag ] T presents a non - linear functional relation with concentration of free sulfite ions [ SO3^2- ]. The solubility of silver sulfite decreases with the pH value in the range of 2 and 8 and increases with the decrease of pH value at pH 〈 2. The optimal pH value for the deposition of silver sulfite is 2. In the best deposition condition, the solubility of silver sulfite decreases with the concentration of sodium sulfite. At the same time, it is approved by thermodynamics analysis and calculation that silver sulfite can be reduced to silver with quite high degree. Accordingly, pH = 2 is the optimal condition for the reduction of silver from solution. Finally, the correctness of the theoretic analysis is verificated by the industrial production.