Department of Chemical Engineering, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran.
Department of Chemical Engineering, Membrane Science and Technology Research Center (MSTRC), Gachsaran Branch, Islamic Azad University, Gachsaran, Iran E-mail:
Water Sci Technol. 2021 Jun;83(12):3092-3109. doi: 10.2166/wst.2021.201.
Wetting and fouling have significantly affected the application of membrane distillation (MD). In this work, a dip-coating method was used for improving surface hydrophobicity of the polyetherimide (PEI) hollow fiber membrane. An air gap membrane distillation (AGMD) process was applied for treatment of the methylene blue (MB) solution. The porous PEI membrane was fabricated by a dry-wet spinning process and the hydrophobic 2-(Perfluoroalkyl) ethanol (Zonyl BA) was used as the coating material. From FESEM, the modified PEI-Zonyl membrane showed an open structure with large finger-like cavities. The modified membrane displayed a narrow pore size distribution with mean pore size of 0.028 μm. The outer surface contact angle of the PEI-Zonyl membrane increased from 81.3° to 100.4° due to the formation of an ultra-thin coated layer. The pure water flux of the PEI-Zonyl membrane was slightly reduced compared to the pristine PEI membrane. A permeate flux of 6.5 kg/m h and MB rejection of 98% were found for the PEI-Zonyl membrane during 76 h of the AGMD operation. Adsorption of MB on the membrane surface was confirmed based on the Langmuir isotherm evaluation, AFM and FESEM analysis. The modified PEI-Zonyl membrane can be a favorable alternative for AGMD of dyeing wastewaters.
润湿和结垢极大地影响了膜蒸馏（MD）的应用。在这项工作中，采用浸涂法提高聚醚酰亚胺（PEI）中空纤维膜的表面疏水性。采用气隙膜蒸馏（AGMD）工艺处理亚甲基蓝（MB）溶液。多孔 PEI 膜通过干湿纺丝工艺制备，疏水性 2-（全氟烷基）乙醇（Zonyl BA）用作涂层材料。从 FESEM 可以看出，改性后的 PEI-Zonyl 膜具有开放的结构，具有较大的指状腔。改性膜显示出较窄的孔径分布，平均孔径为 0.028μm。由于形成了超薄的涂层，PEI-Zonyl 膜的外表面接触角从 81.3°增加到 100.4°。与原始的 PEI 膜相比，PEI-Zonyl 膜的纯水通量略有降低。在 AGMD 运行 76 小时期间，PEI-Zonyl 膜的渗透通量为 6.5kg/m h，MB 截留率为 98%。基于 Langmuir 等温线评价、AFM 和 FESEM 分析，证实了 MB 在膜表面的吸附。改性的 PEI-Zonyl 膜可为染色废水的 AGMD 提供有利的选择。
