Anti-wetting behavior of negatively charged superhydrophobic PVDF membranes in direct contact membrane distillation of emulsified wastewaters
Anti-wetting behavior of negatively charged superhydrophobic PVDF membranes in direct contact membrane distillation of emulsified wastewaters
复制标题
带负电超疏水PVDF膜在直接接触膜蒸馏乳化废水中的抗润湿行为
DOI：
10.1016/j.memsci.2017.04.040
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发表时间：
2017-08-01
影响因子：
9.5
通讯作者：
He, Tao
中科院分区：
文献类型：
--
作者：
Chen, Ying;Tian, Miaomiao;He, Tao
膜润湿是导致膜蒸馏性能下降的关键因素。在这项工作中，超疏水膜的挑战，在直接接触膜蒸馏（DCMD）过程中使用阳离子/阴离子表面活性剂乳化的水包油乳液，以评估在一个高度苛刻的环境中的超疏水表面的抗润湿性能。测定了膜的接触角、Zeta电位和DCMD性能。结果表明，PVDF超疏水膜表面带强负电荷，对阴离子表面活性剂乳化废水具有较好的膜分离性能，但对阳离子表面活性剂乳化废水具有较强的润湿性。相比之下，原始的疏水PVDF膜经历了严重的润湿，无论是表面活性剂稳定的乳液。基于EDL、酸碱和疏水-疏水相互作用，利用扩展的DLVO理论解释了膜-污垢相互作用。进行超疏水膜的清洁，并且对于用于处理带负电荷的乳液的膜，实现了膜性能的恢复。本研究概述了实验证据和超疏水表面的负电荷对于稳定膜蒸馏性能的重要性，这可能有助于未来蒸馏膜的发展。
Membrane wetting is a key issue in causing deleterious performance in membrane distillation. In this work, superhydrophobic membranes were challenged in a direct contact membrane distillation (DCMD) process using cationic/anionic surfactant emulsified oil-in-water emulsions in order to assess the antiwetting properties of superhydrophobic surfaces in a highly demanding environment. Contact angle, Zeta potential and DCMD performance of the membrane were determined. It was found that superhydrophobic PVDF membranes exhibited strongly negative charges on the surface, as well as stable MD performance in concentrating the anionic surfactant emulsified waste water, but suffered from severe wetting when cationic surfactant was used. In contrast, the virgin hydrophobic PVDF membrane experienced severe wetting for either surfactant stabilized emulsions. Extended DLVO theory was utilized to explain the membrane-foulant interaction based on the EDL, acid-base and hydrophobic-hydrophobic interaction. Cleaning of superhydrophobic membranes was performed and restore of membrane performance was achieved for membranes that were used for treatment of negatively charged emulsions. This research outlined the experimental evidence and the importance of negative charges of a superhydrophobic surface for a stable membrane distillation performance, which may be helpful for future development of distillation membranes.