基于膜吸收法处理实际高浓度蚀刻废液的研究

In order to realize the efficient treatment of high-concentration etching waste solution in printed circuit board production field, the process of membrane absorption+Na₂S breaking+PAC coagulation and precipitation was established to investigate the ammonia nitrogen and copper removal efficiency of the actual high-ammonia-nitrogen etching waste solution, and the process conditions were optimized. Single factor experiments were designed to explore the influences of pH and flow rate of feed liquid, concentration and flow rate of absorption solution, stages of membrane modules and temperature on NH₄⁺-N removal rate, mass transfer coefficient and membrane flux, and the optimal operating parameters were determined as follow:feed liquid pH=10.5, flow rate of feed liquid was 3.6 cm/s, absorption liquid concentration was 2.0 mol/L, flow rate of absorption liquid was 1.1 cm/s, film stages was 18, temperature was 40 ℃. Under the above conditions, NH₄⁺-N could be reduced from 82 000 mg/L to about 100 mg/L, the removal rate of NH₄⁺-N remained more than 99.8%, the mass transfer coefficient was 3.38×10^-6 m/s, and the transmembrane flux was 40.7 mg/ (m²·s). At the same time, the process conditions of Na₂S breaking and coagulation and precipitation were optimized. Na₂S was added to the copper ammonia complex at the condition of n(S^2-)/n(Cu²⁺)= 1.4, and 150 mg/L PAC was added to the breaking solution for coagulation and precipitation, the copper concentration in effluent could be controlled below 0.5 mg/L. The results of repeated experiments showed that the membrane absorption method had stable performance in long-term operation, and had good applicability to the treatment of high ammonia nitrogen production wastewater of printed circuit board. It was one of the effective technical approaches to solve the pollution problem of high concentration etching waste solution.