Process Research In Removal Of Pollutants Of Electroless Nickel Plating Wastewater

Electroless nickel plating wastewatercomposed by a large amount of waste wash water During nickel plating and aging solution.complexing agents and other additives are usually added in the bath to ensure the quality of nickel plating and lifetime of the bath,for instanceammonium citrate.These additives with nickel ions to form stable complexes,using conventional neutralization and sedimentation, coagulation and other treatment methods have limitations on the removal of nickel complex, it’sdifficult to ensure that heavy metal ions below the emission limits. Simultaneously these additives also improve the wastewater COD, ammonia nitrogen content, increasing the difficulty of wastewater treatment.This paper proposed using Fenton- chlorine oxidation and iron-carbon micro-electrolysis-Fenton- chlorine oxidation treated electroless nickel plating wastewater which complexed with ammonium citrate,It’s was based on Fenton method can generate strong oxidizing ? OH can effectively remove organics and iron-carbon micro-electrolysis method can treatmeng wastewater by redox, primary batteries, flocculation and sedimentation,and chlorine oxidation can effectively remove ammonia.On the process operating parameters were optimized and explore the mechanism of removal of the nickel complex,in order to find a low-cost, high-efficiency treatment process for electroless nickel plating wastewater treatment and provide technical parameters and theoretical basis for engineering applications.Experimental results showed that, Fenton- chlorine oxidation process of electroless nickel plating wastewater optimum operating parameters are as follows:a H2O2 dosage of 300mg/L,Fe SO4/H2O2=4:1,Fenton reaction p H was 4.0,75 min of Fenton reaction time and under the aeration conditions,a Na Cl O dosage/ammonia of 10:1,25 min of reaction time,a p H of 8.0.Under these the conditions Fenton- chlorine oxidation process wastewater effluent quality as follows:a nickel content of 0.06mg/L,a ammoniacontent of 6.6mg/L,total nitrogencontent of 10.7mg/L,total phosphoruscontent of 0.3mg/L,COD content of 43mg/L,p H were 8.4~8.8.Iron-carbon micro-electrolysis-Fenton- chlorine oxidation process of electroless nickel plating wastewater optimum operating parameters are as follows:a iron dosage of 40g/L,a Fe/C ratio of 2:1,a p H of 3.0,reaction time of 20 min,a H2O2/Fe2+ ratio of 1.2,60 min of Fenton reaction time,and under the aeration conditions,a Na Cl O dosage/ammonia of 10:1,25 min of reaction time,a p H of 8.0.Under these the conditions Iron-carbon micro-electrolysis-Fenton- chlorine oxidation process wastewater effluent quality as follows:a nickel content of 0.06mg/L,a ammoniacontent of 5.1mg/L,total nitrogen content of 8.7mg/L,total phosphorus content of 0.3mg/L,COD content of 46mg/L,p H were 8.3~8.6.An equimolar concentration graded method of spectrophotometry was used to measured the complex stability constants.The results showed that stability constants of nickel and ammonium citrate complexed was 5.41 and stability constants of ferric iron and ammonium citrate complexed was 14.31.It’s illustrated that the complexed of ferric iron and ammonium citrate was more stable than the complexed of nickel and ammonium citrate,nickel ions can be replaced out of complexedand be removed with nikel hydroxide precipitate.