Abstract In this paper, the low-temperature thermally induced phase separation (L-TIPS) method was adopted to prepare a high-performance polyvinylidene fluoride (PVDF) hydrophobic membrane for membrane distillation (MD) with non-solvent polyethylene glycol-400 (PEG400) and solvent triethyl phosphate as a fully water-soluble mixed diluent. In the process of L-TIPS membrane formation, the unidirectional regulatory role of coagulation bath temperature on cross-section radius of the PVDF hollow-fiber membrane was analyzed. The results show that the tensile strength of the membrane increases with the increase of the external coagulation bath water temperature, which is the opposite of the general rule. PEG400 is employed to regulate the membrane structure, and more specifically to increase the cellular structure (a positive impact on tensile strength) and reduce the sphere-packed aggregation structure (a negative impact on tensile strength). When the coagulation bath temperature is 60 °C, the tensile strength of the membrane reaches 6.21 MPa (more than 2–4 times higher than the hydrophobic membranes reported). Meanwhile, the PVDF hollow-fiber hydrophobic membrane also has a high flux, the vacuum membrane distillation flux reaches 30.6 kg m −2 h −1 , which is 14.6 times higher than that at the coagulation bath temperature of 15 °C.

中文翻译：

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凝固浴温度对PVDF中空纤维膜横截面半径的单向调节作用

摘要 本文采用低温热致相分离 (L-TIPS) 方法制备了高性能聚偏二氟乙烯 (PVDF) 疏水膜，用于膜蒸馏 (MD) 与无溶剂聚乙二醇-400 (PEG400 ) 和溶剂磷酸三乙酯作为完全水溶性的混合稀释剂。在L-TIPS成膜过程中，分析了凝固浴温度对PVDF中空纤维膜横截面半径的单向调节作用。结果表明，膜的拉伸强度随着外凝浴水温的升高而增加，与一般规律相反。PEG400 用于调节膜结构，更具体地说，增加蜂窝结构（对拉伸强度有积极影响）并减少球状聚集结构（对拉伸强度有负面影响）。当凝固浴温度为 60 °C 时，膜的拉伸强度达到 6.21 MPa（比报道的疏水膜高 2-4 倍以上）。同时，PVDF中空纤维疏水膜还具有高通量，真空膜蒸馏通量达到30.6 kg m -2 h -1 ，是凝固浴温度15℃时的14.6倍。