【摘要】 采用双极膜电去离子技术(EDI-BP)处理低浓度模拟含镍废水,研究了Ni(OH)2沉淀产生的原因及消除措施。结果表明:沿膜器高度的电流密度分布不均匀;浓水室靠近产水出水端阴膜面产生的Ni(OH)2沉淀由于局部Ni2+、OH-离子浓度过高造成。第一脱盐室进水端阳膜面产生的Ni(OH)2沉淀由水解离造成。采用降低原水pH、浓水pH等措施能够有效地避免沉淀的产生;在原水Ni2+浓度30 mg/L、流速0.317 cm/s、pH值2.77,浓水pH 1.18和电流密度9.5 mA/cm2的条件下进行浓缩试验,试验稳定运行285 h,得到的产水电导率约为1.5μS/cm,产水中未检测出Ni2+离子,浓水中Ni2+浓度可达2.7 g/L,浓缩倍数达90倍。更多还原

【Abstract】 The generation and avoidance of Ni(OH)2 precipitation during the treatment of the simulated dilute Ni2+-containing wastewater were investigated by electrodeionization with bipolar membrane. The results show that, the current density distribution along the height of EDI-BP stack is uneven. The reason of Ni(OH)2 precipitates on the surface of anion membrane near the outlet of feed in concentrate compartment is high local concentration of Ni2+ and OH-. Ni(OH)2 precipitating on the surface of the cation membrane near the inlet of first dilute compartment due to the splitting of water. By lowering the pH value of concentrate and feed, the generation of Ni(OH)2 precipitate can be avoided. Under the condition of Ni2+ concentration, flowrate, pH value of feed, pH value of concentration and the current density are 30 mg/L, 0.317 cm/s, 2.77, 1.18 and 9.5 mA/cm2, respectively, the concentration experiment carries stably for 285 h. The diluate is Ni2+-free at the conductivity of 1.5 μS/cm, and the concentration of Ni2+ in concentrate reaches 2.7 g/L which is 90 times of that in feed.更多还原