| In recent years,the electronic industry has developed quickly with the rapid development of China’s economy,and China has become the world’s largest PCB manufacturing country,whose PCB output value has accounted for more than half of the world’s total output value.However,a large amount of electroplating wastewater is produced every year,which contains a large amount of copper ions.If the wastewater was not properly treated,it will not only cause serious impact on the environment,but also cause serious waste of resources.Therefore,in this paper,for electroplating copper containing wastewater,ion exchange resin method for copper ion enrichment experiment;chemical precipitation method,electrolysis method,nanofiltration +cooling crystallization method for copper ion recovery experiment,put forward an efficient and economic ion exchange method + nanofiltration + cooling crystallization process,used in the actual treatment of PCB wastewater,to achieve wastewater discharge and copper ion recovery efficiency Fruit.The conclusions of this paper are shown as following:(1)Four kinds of ion exchange resins(001×7 resin,D001 resin,Dusheng ch-90 resin and Zhengguang d851 resin)were selected for static adsorption experiment.Experiments showed that: 001 × 7 resin and D001 resin had similar performance,and the adsorption rate of copper ion was significantly higher than that of Dusheng ch-90 resin and Zhengguang d851 resin.At 25 ℃,pH value 4 and initial concentration of 100mg/L,the adsorption rate of 001 × 7 resin and D001 resin reached more than 99%.Considering the low price of 001 × 7 resin,it was selected used in wastewater treatment and reconstruction project;(2)The recovery of copper ions was studied by chemical precipitation,electrolysis and nanofiltration cooling crystallization experiments.The recovery of copper ions by sodium sulfide precipitation and sodium hydroxide precipitation was studied.The product of sodium sulfide precipitation method was copper sulfate,the highest recovery rate was 99.3%;the product of sodium hydroxide precipitation method was copper hydroxide,the highest recovery rate was 99.0%.The effects of electrolysis time,pH,distance between plates,voltage,initial concentration and electrode materials on the experimental results were studied.The optimum conditions for copper recovery by electrolysis were obtained as followings: titanium electrode was used as anode,pH value was 3,spacing between electrode plates was 4cm,voltage was 4V,and initial concentration was 12g/L.Nanofiltration cooling crystallization method was used to concentrate copper ions by nanofiltration,so that the copper ion concentration reached40g/L,and the pH value was adjusted to about 2.The crystallization of five water copper sulphate was obtained,and the purity was over 99%.(3)The technologies of ion exchange,nanofiltration and cooling crystallization were applied to the process transformation of electroplating wastewater from a PCB Factory in Guangdong Province.After adopting the new process,the parameters of the total effluent had been significantly reduced,among which the concentration of copper ion,ammonia nitrogen and total nitrogen were reduced by more than 50%,COD and total phosphorus were also reduced by more than 25%,the recovery rate of copper ions was increased by 11.26%,and the economic cost of recovering copper per ton was reduced by 2003.9 yuan,which had achieved good wastewater treatment effect and economic effect. |
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