KAGAKU KOGAKU RONBUNSHU, Vol.30, No.5, 592-597, 2004
Particulation of copper Sulfides produced by sulfurization of Cu-plating wastewater and its effect on filtration characteristics
In order to recover metal from plating wastewater, an attempt was made to precipitate copper in the form of sulfides, which tend to form fine particulates. Model plating wastewater containing 20, 100 or 250 mg-Cu/dm(3), and real plating wastewater containing Cu, Zn and Ni at concentrations of 100 mg/dm(3) were employed. Na2S, Na2S2 and Na2S4 were used as sulfurization agents at a constant pH. Particulate size and filtration characteristics of precipitated copper sulfides were investigated. Results showed that copper sulfide particulates formed with Na2S were the smallest in size and slowest in growth rate compared to those formed with Na2S2 and Na2S4. At a constant pH of 1.4-1.5, no particulates of copper sulfides were observed when the amount of Na2S added to Cu solution was controlled below 1.5 mol/mol-Cu. On the other hand, particulates of copper sulfides were formed when the amount of Na2S exceeded 1.0 mol/mol-Cu at pH 2.4-2.5. The filtration characteristics such as the mean specific filtration resistance and compressibility coefficient of copper sulfide cakes formed with sulfides of sodium reduced in size in the order Na2S