高铁酸钾氧化自絮凝处理实际化学镀镍废槽液

Treatment of actual electroless nickel plating bath waste by potassium ferrate oxidation and self-flocculation

化学镀镍工艺广泛应用于工业生产领域,并产生大量废水。此类废水一般由预处理工艺废水、镀件清洗水、废镀液及其他废水组成,成分复杂,具有微生物毒性,如直接排放会对自然环境造成严重污染。采用高铁酸钾(K_(2)FeO_(4))对含高浓度Ni和COD的化学镀镍废槽液进行处理,探讨K_(2)FeO_(4)浓度、废水初始pH对废水处理效果的影响。结果表明,K_(2)FeO_(4)最适浓度为5 mmol/L,最佳废水初始pH为3,对络合态Ni的破络效率最高可达99%,COD去除率最高达80%。超高效液相色谱-质谱(UPLC-MS)表征结果显示,废水中的Ni主要以苹果酸-Ni形态存在。K_(2)FeO_(4)处理化学镀镍废槽液的机理可能为:K_(2)FeO_(4)先与废水中的还原物质反应得到还原产物Fe(Ⅲ),再与Ni-有机络合物发生置换使Ni游离,同时,Fe(Ⅲ)的絮凝作用可降低废水的COD。

Electroless nickel plating process is widely used in industrial fields and generates a large amount of wastewater.This type of wastewater generally consists of pretreatment process wastewater,cleaning water,waste plating solution and other wastewater with complex composition and microbial toxicity,which will cause serious pollution to the natural environment if discharged directly.Potassium ferrate(K_(2)FeO_(4))was used to treat bath waste of electroless nickel plating containing high concentrations of Ni and COD.The effects of K_(2)FeO_(4) concentration and initial pH of wastewater on treatment were investigated.The results showed that the optimum concentration of K_(2)FeO_(4) was 5 mmol/L and the optimal initial pH of the wastewater was 3.The complex-breaking efficiency of K_(2)FeO_(4)was up to 99%for complexed Ni and the removal rate of COD was up to 80%.UPLC-MS characterization showed that Ni in the wastewater mainly existed in the form of malic acid-Ni.The reaction mechanism of K_(2)FeO_(4) for bath waste of electroless nickel plating may be as follows:K_(2)FeO_(4) reacts with the reducing substances in the wastewater to form reduction product Fe(Ⅲ),and then replaces with Ni-organic complex.Meanwhile,the flocculation effect of Fe(Ⅲ)can reduce COD of the wastewater.