Study On The Advanced Treatment Of Nickel Citrate By Three-Dimensional Electrocatalytic Oxidation

Citric acid has many functions such as acid,buffer and complexing,It is widely used in chemical nickel plating as buffering agent,complexing agent.The Composition of electroless nickel plating wastewater containing complex,nickel ion,hypophosphite and phosphite and refractory organic compounds,which have carcinogenic,teratogenic and mutagenic and low biodegradability,become a difficulty in the field of water treatment.Electrocatalytic oxidation method is the use of electrodes and produce reactive oxides directly or indirectly degradation of pollutants,because of its high efficiency,wide range of applications,easy to control and no secondary pollution and other characteristics,has been widespread concern.This paper was based on the three-dimensional electrocatalytic oxidation technology,the degradation process of citric acid and Ni(II)–citrate complexes under three-dimensional electrocatalytic oxidation was studied,and the application in the electroless nickel plating wastewater which contains Citric acid complexing agent was also conducted.The main results are as follows:The three-dimensional electrocatalytic oxidation system was formed by using the graphite plate as the anode and the anode and the ceramic particles as the particle electrode.The degradation process of citric acid simulated wastewater and citric acid complex nickel wastewater was studied.The effect of process parameters on the efficiency of three-dimensional electrocatalytic oxidation was studied.The degradation mechanism was analyzed and the kinetics of the degradation process was simulated.The results showed that the three-dimensional electrocatalytic oxidation could destroy the citric acid complex structure,citric acid and nickel.The removal process is in accordance with the first order kinetics.The electroless nickel plating wastewater was treated by electrocatalytic oxidation-chemical precipitation process.The optimum conditions for the electrocatalytic oxidation were 17.5V,the initial pH was 7,the dosage of NaCl was 17 g / L,the reaction time was 90 min.The single factor experiments showed that the optimum conditions of chemical precipitation reactions were as follows: without pH adjustment,using CaO as precipitant,the optimum CaO dosage was3g/L,and the reaction time was 30 min.Under the above operation conditions,the removal rates of COD,nickel and total phosphorus could reach 94.48%,99.71%,99.96%,and the effluent COD,nickel and total phosphorus could be less than 43mg/L,0.08mg/Land0.24mg/L,respectively.It can meet the requirements of the comprehensive emission standard for electroplating pollutants(GB 21900-2008)in Table 3...