Treatment Of Micro-Etching Waste Solution By Special Nanofiltration Membrane

With the mass production and general use of printed circuit board, the waste etching solution which was engendered during the production of printed circuit board is increasing year by year. The waste etching solution contains copper and acid, with high practical value. The waste etching solution that contains high level of copper has been researched abundantly both at home and abroad, and also has compared mature treatment process. However, the waste micro-etching solution that contains low level of copper is still having no effective treatment technology.The main content of this paper was research for the removal of oxidant in the waste solution from H2O2/H2SO4and Na2S2O8/H2SO4systems, and the treatment of micro-etching waste solution by special nanofiltration membrane. After this process, the concentrate containing relatively high concentrations of copper was conducive for the subsequent processing and permeate containing acid could be reused in the micro-etching process. The research had found a new and effective way for the treatment of micro-etching waste solution.In the experiments of oxidant removal, the reduction method, absorption method and electrolysis method were compared using the single factor analysis method to optimize the operating conditions.According to results of experiments, the highest removal efficiency for H2O2/H2SO4system was97.1%under the condition of normal temperature, acidity [H+] at2.64mol·L-1, feed ratio of n(Cu):n(H2O2) at1.0, reaction time15～20min, stirred rate at300r·min-1and the highest removal efficiency Na2S2O8/H2SO4system was93.2%under the condition of normal temperature, acidity [H+] at1.3mol·L-1, feed ratio of n(Cu):n(Na2S2O8) at1.0, reaction time70min,stirred rate at300r·min-1.In nanofiltration membrane processing experiments, the influences of operational factors, such as operating pressure, feed flow and concentration factor on membrane performances were investigated by using single factor method. Through comprehensive comparisons, APE type of nanofiltration membrane from Harrison Western Group was chosen for the separation of waste solution. According to the results of experiments, the average retention rates of Cu2+, Na+and H+were93%,70%and30%respectively. The micro-etching waste solution that contented copper5.9g·L-1could be concentrated to21.5g·L-1and the volume was decreased by80%. The experiment realized the resource utilization of micro-etching wastewater by membrane separation.Finally, the membrane equipment and the electrolytic equipment were combined in order to maintain the efficiency of the electrolytic process. The results showed that the process could maintain the copper ion concentration in the electrolytic cell and improve the electrolysis efficiency, at the same time, the permeate could be reused in the micro-etching process.