Separation and Purification Technology ( IF 8.1 ) Pub Date : 2020-09-25 , DOI: 10.1016/j.seppur.2020.117762 Renwei Zhang , Wenyong Tang , Haifu Gao , Chunrui Wu , Stephen Gray , Xiaolong Lu
In-situ construction of superhydrophobic polyvinylidene fluoride (PVDF) membrane was prepared through nonsolvent induced phase inversion process for direct contact membrane distillation (DCMD). Saturated sodium chloride aqueous solution (NaCl-H2O) was added to the casting solution as a green phase inversion inducing agent. The variation of polymer crystal and the formation mechanism of micro-nano structure on membrane surface were studied. The results showed that NaCl crystals could act as nucleus for the pre-gelation and crystallization of PVDF chains. The “harsh” nonsolvent, water, accelerated the gelation process. When the optimum amount of NaCl-H2O was added, superhydrophobic membrane with lotus leaf like micro-nano spherical structure and interconnected channels was obtained. The pure water contact angle reached 155.3° with DCMD flux of 54.5 L/m2∙h, which was about 1.6 times for the membrane without NaCl-H2O addition. The stability was also improved owing to the superhydrophobic structure.
中文翻译:
通过NaCl-H 2 O诱导聚合物初始凝胶原位构建超疏水PVDF膜用于膜蒸馏
超疏水聚偏二氟乙烯(PVDF)膜的原位构建是通过非溶剂诱导相转化过程制备的,用于直接接触膜蒸馏(DCMD)。将饱和氯化钠水溶液(NaCl-H 2 O)添加到浇铸溶液中作为生相转化诱导剂。研究了聚合物晶体的变化和膜表面微纳米结构的形成机制。结果表明,NaCl晶体可以作为PVDF链预凝胶化和结晶的核。“苛刻”的非溶剂水加速了凝胶化过程。当 NaCl-H 2的最佳用量为添加O,获得了荷叶状微纳米球形结构和相互连接的通道的超疏水膜。纯水接触角达到155.3°,DCMD通量为54.5 L/m 2 ∙h,约为未添加NaCl-H 2 O的膜的1.6倍。由于超疏水结构,稳定性也得到了提高。