基于PTFE中空纤维膜的多元重金属溶液膜蒸馏探索研究

Treatment of Multivariate Heavy Metal Solution by Membrane Distillation Based on PTFE Hollow Fiber Membrane

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。

The separation membrane,polytetrafluoroethylene（PTFE） hollow fiber hydrophobic membrane,was applied in direct contact membrane distillation（DCMD） and vacuum membrane distillation（VMD） processes for the concentration treatment of multivariate heavy metal solution.The variation of the membrane distillation（MD） flux,the conductivity of product water and membrane fouling were investigated,separately.The influence of heavy metal ions on the MD performance was also studied.The differences between the tube-side and shell-side feed solution of VMD were studied and the mechanism was analyzed by scanning electron microscope（SEM）.The results showed that the copper,nickel and zinc ions had no significant effect on the stability of MD flux and the quality of producing water.The tube-side feed solution of VMD caused the crystal sediment and the leakage of metal ions much easier,while the shellside feed solution of VMD performed well.The sediment was copper sulfate analyzed by energy dispersive spectroscopy（EDS）.The SEM images showed that the differences of inner and outer microstructure surface of membrane were the main reason for the different performance of two types of VMD.This study showed that it was feasible to use MD process to deal with multivariate heavy metal solution with appropriate operation.