Study on Spectrophotometric Determination of Trace Copper after Flotation Separation using Sodium Chloride-Ammonium Thiocyanate-Dodecyl Dimethyl Benzyl Ammonium Chloride System

摘要

The paper presents a novel method for the spectrophotometric determination of trace Cu~(2+) after flotation separation using sodium chloride-ammonium thiocyanate-dodecyl dimethyl benzyl ammonium chloride system. The effects of the dosages of NH_4SCN and dodecyl dimethyl benzyl ammonium chloride (DDBAC), various salts and acidity etc. on the flotation yield of Cu~(2+) have been investigated. The possible flotation separation mechanism of Cu~(2+) was discussed. The results showed that by controlling pH4.0, in NaCl-NH_4SCN-DDBAC system, the water-insoluble ternary association complex of (DDBAC)_2[Cu(SCN)_4] which produced by Cu~(2+) and SCN~-, DDBAC cation (DDBAC~+) floated above water phase and liquid-solid phases were formed with clear interface, while Mn~(2+), Ni~(2+), Fe~(2+) and Al~(3+) could not be floated, so Cu~(2+) was floated quantitatively. Thereby, the quantitative separation of Cu~(2+) from the above metal ions could be achieved. A new spectrophotometric method of determination of trace copper by flotation separation was established. The proposed method has been successfully applied to the determination of Cu~(2+) in various environmental water samples with satisfactory results.