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以聚四氟乙烯(PTFE)中空纤维疏水膜作为分离膜,分别采用直接接触膜蒸馏(DCMD)和真空膜蒸馏(VMD)对多元重金属溶液进行浓缩处理,通过考察膜蒸馏通量、产水电导率的变化及膜污染情况,探讨重金属离子对膜蒸馏性能的影响,考察VMD内进外抽和外进内抽两种操作方式的差异,并借助扫描电镜(SEM)分析产生差异的机制。结果表明,铜锌镍3种金属元素并未对膜蒸馏通量稳定性及产水水质产生显著影响;研究还发现采用VMD内进外抽操作方式更容易导致膜表面晶体沉积和重金属离子渗漏,经能谱仪检测分析管内表面沉积物为硫酸铜晶体,外进内抽方式则性能良好;电镜分析表明,膜丝内外表面微观结构的差别是造成内进外抽和外进内抽膜蒸馏性能差异的主要原因。本研究结果表明,采用合适的操作方式,膜蒸馏处理多元重金属溶液是可行的。
Using polytetrafluoroethylene (PTFE) hollow fiber hydrophobic membrane as separation membrane, direct contact membrane distillation (DCMD) and vacuum membrane distillation (VMD) were respectively used to concentrate the heavy metal solution. The effects of membrane distillation flux, Rate changes and membrane fouling conditions were investigated. The effects of heavy metal ions on the membrane distillation performance were investigated. The differences between the two modes of operation in and out of the pump were investigated, and the mechanism of the differences was analyzed by scanning electron microscopy (SEM). The results showed that the three metal elements of Cu, Zn and Ni had no significant effect on the stability of membrane distillation flux and water quality of production. The study also found that the use of VMD in and out pumping easier to cause crystal deposition and heavy metal ion leakage The results of EDS showed that the deposits on the inner surface of the tube were copper sulfate crystals, and the external pumping method was good. Electron microscopy analysis showed that the difference between the microstructures of the inner and outer surfaces of the membrane was caused by internal and external pumping The main reason for the difference in performance. The results of this study show that it is feasible to use membrane distillation to treat multiple heavy metal solutions with proper operation.