Na_2S-DDTC深度处理络合Ni高浓度电镀废水

对比选用有机巯基类高分子螯合剂(DDTC)、无机硫(Na_2S)和氢氧化钠(Na OH)作为电镀Ni的捕集剂,对模拟电镀废水中的络合Ni进行深度处理,重点考察了反应p H值、药剂投加量、反应时间以及絮凝剂种类等因素对Ni的去除效果的影响,并对去除机理进行了探究.结果表明:对于高浓度络合Ni模拟废水ρ(Ni)=300mg/L,在p H9.0,Na_2S与DDTC投加比为ρ(Na_2S)/ρ(DDTC)=10,其中ρ(Na_2S)=600mg/L,ρ(DDTC)=60mg/L,反应时间t=6.0min,PAM投加量1.0mg/L时,Ni_2+的残余浓度为0.064mg/L,低于0.1mg/L达到废水排放标准;此外对Na_2S-DDTC与Ni反应生成的沉淀的溶出试验表明,在自然状态下该沉渣具有较高的稳定性,不会形成二次污染;通过粒径分布统计分析以及SEM表面形态观察分析可知Na_2S-DDTC复配药剂对Ni的捕集作用主要为有絮凝-共沉淀的协同作用.通过本研究,可以为Na_2S-DDTC处理高浓度含络合Ni电镀废水工艺设计提供理论支持.

Application of high-level complex Ni removal from electroplating wastewater by the Na2S-DDTC

In this study, the organic mercapto polymer chelating agent (DDTC), Na₂S and NaOH were selected as the capturing agent and used to remove complex Ni deeply from the electroplating plant wastewater. It paid the key focus on the study of reaction pH, pharmaceutical dosage, reaction time and other factors that could influence the removal of Ni. Besides, the mechanisms of Ni²⁺ removing by Na₂S-DDTC was also discussed. The results showed that Na₂S-DDTC had a high efficiency under the following conditions: ρ(Ni)=300mg/L of initial nickel concentration, pH 9.0, Na₂S and DDTC dosing ratio was ρ(Na₂S)/ρ(DDTC)=10, where ρ(Na₂S)=600mg/L, ρ(DDTC)=60mg/L, the reaction time t=6.0min, the dosage of PAM was 1.0mg/L, leading to 0.064mg/L of residual Ni²⁺ concentration, which meeting the nickel special emission limit of the emission standard of pollutants for electroplating (<0.1mg/L). Furthermore, precipitation dissolution test about Na₂S-DDTC mixed with Ni showed that, the hybrid sediment had a high sability under the state of nature, and did not cause secondary pollution. The particle size distribution was studied and a SEM method was used to observe the precipitation surface, the results indicated Na₂S-DDTC had a certain synergy of flocculation and coprecipitation. Through this study, it could provide theoretical support for process design to deal with wastewater containing high complex Ni concentration using Na₂S-DDTC.