Cadmium ions in the wastewater discharged from cyanide-free potassium chloride cadmium electroplating process was treated by sodium dimethyldithiocarbamate, a heavy metal scavenger, based on the precipitation of cadmium dimethyldithiocarbamate. The residual concentration of cadmium ions in a wastewater containing 180 mg/L cadmium ions initially is compliant with the Table 2 stipulated by the Emission Standard of Pollutants for Electroplating(GB 21900-2008) after treatment at pH 2.47-9.34,and even meets the requirement of the Table 3 in GB 21900-2008 standard within the pH range of 4.43-7.68. The effluent is hard to be compliant with the emission standard if the initial concentration of nitrilotriacetic acid and other complexing agents is too high, even though the dosage of sodium dimethyldithiocarbamate is increased.%以重金属捕捉剂二甲基二硫代氨基甲酸钠处理氯化钾无氰镀镉废水中的镉离子,可生成二甲基二硫代氨基甲酸镉沉淀物.对于含180 mg/L镉离子的废水,在pH为2.47 ~ 9.34的范围内处理后,残留的镉离子浓度能满足GB 21900-2008《电镀污染物排放标准》中"表2"的要求,pH为4.43 ~ 7.68时甚至满足"表3"的要求.废水中氨三乙酸等配位剂的初始浓度不能太高,否则即使增大二甲基二硫代氨基甲酸钠的用量,也很难达标排放.
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