五硫代碳酸钠处理含Cr(Ⅵ)水溶液的实验研究

Experimental study on treatment of aqueous Cr(Ⅵ) solution by sodium polythiocarbonate

采用一种新型还原剂五硫代碳酸钠（Na2CS5）处理含Cr（Ⅵ）水溶液。考察了含Cr（Ⅵ）水溶液的pH值、五硫代碳酸钠的用量、反应时间、沉淀时间和Cr（Ⅵ）的浓度等对Cr（Ⅵ）去除率的影响。结果表明,含Cr（Ⅵ）水溶液初始pH值和沉淀阶段溶液的pH值分别控制为1.5和8~8.5,n（Cr2O72-）∶n（CS52-）=1∶3,反应和沉淀时间均为60 min时,Cr（Ⅵ）去除率高达99.9%,残留Cr（Ⅵ）的浓度〈0.041 mg/L,小于污水综合排放标准（GB8978-1996）。沉淀物经处理可制得重要的化工原料Cr2O3。

A new reductant,sodium polythiocarbonate,was used in the purification of aqueous Cr（Ⅵ） solution.Factors including pH value,reductant dosage,reaction time,precipitation time and different Cr（Ⅵ） concentrations on Cr（Ⅵ）removal rate,were investigated.Results indicated that Cr（Ⅵ） removal efficiency was over 99.9% and Cr（Ⅵ） concentration was lower than 0.041 mg/L in the effluent,which could meet with the requirements of the national discharge standard at pH 1.5 and 8～8.5 in the original solution and precipitation stage,respectively,with the molar ratio of the amount of substance of dichromate ion to sodium polythiocarbonate 1∶3,for reaction and precipitation time 60 min.The chemical raw material Cr2O3 was prepared.