复配Na2S-DDTC处理高浓度含Ni电镀废水

为降低实际工程中二硫代氨基甲酸盐（DTC）类螯合剂用药成本，以某电镀厂高浓度含络合Ni电镀漂洗废水作为处理对象，研究了一种有机巯基类螯合剂（简称DDTC）复配Na2S去除Ni离子的效果与机理，并重点对反应pH、DDTC与Na2S单独、复配投加量、含Ni初始浓度等几个因素的影响进行探究。实验结果表明：反应pH值对Ni的去除有较大影响，pH=9.0时Na2S-DDTC对Ni的去除效果最好；Na2S-DDTC对电镀络合Ni具有很好的捕集功能，优于Na2S、DDTC单独使用，其中当pH=9.0，nNa2S/nNi=1.5，ρ（DDTC）=200 mg·L-1时，Ni的剩余浓度为0.062 mg·L-1，达到《电镀污染物排放标准》（GB 21900-2008）中关于Ni污染物特别排放限值要求（-1）；Na2S-DDTC处理不同初始浓度的含Ni废水具有较宽的应用范围，其中Na2S对Ni的用量存在nNa2S/nNi=1.5的化学计量关系，DDTC存在不同的最佳投药量；Na2S与DDTC复配使用具有一定的协同作用。

Na2S-DDTC composite agents for treatment of electroplating wastewater with high Ni concentrations

In the effort to reduce the cost of the dithiocarbamate (DTC) class chelating agent in actual projects, we studied the effectiveness and the mechanisms to remove the Ni ion from a type of organic sulfhydryl chelating agent (DDTC), compounding with Na2S. We employed the wastewater from an electroplating factory, containing high-density electroplating complexation Ni, as the treatment object. The research focused on various factors, such as the reaction pH, separate and compound dosages of Na2S and DDTC, and the initial concentration of the Ni content. The experimental results showed that the reaction pH strongly influenced the removal of Ni, and at pH 9.0, the Na2S-DDTC compound was superior for removing Ni. The Na2S-DDTC compound has an efficient trapping function for electroplating complexation Ni, which was superior to using Na2S and DDTC separately. The residual Ni concentrations were 0.062 mg·L-1 when pH=9.0, nNa2S/nNi=1.5, ρ(DDTC)=200 mg·L-1, which could conform to the Ni special discharge standard for electroplating (GB 21900-2008)(-1). The Na2S-DDTC compound has a wider application range for treating wastewater that contains different initial concentrations of Ni. A stoichiometric relation was shown between Na2S and the dosage of Ni, namely, nNa2S/nNi=1.5, and the optimal coagulant dose for DDTC was different. Compounding Na2S with DDTC had a certain synergistic effect.