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Membrane Water Treatment   Volume 10, Number 4, July 2019, pages 287-298
DOI: https://doi.org/10.12989/mwt.2019.10.4.287
 
Preparation of highly hydrophobic PVDF hollow fiber composite membrane with lotus leaf-like surface and its desalination properties
Hongbin Li, Xingchen Zi, Wenying Shi, Longwei Qin, Haixia Zhang and Xiaohong Qin

 
Abstract     [Buy Article]
    Lotus leaf has a special dual micro and nano surface structure which gives its highly hydrophobic surface characteristics and so-called self cleaning effect. In order to endow PVDF hollow fiber membrane with this special structure and improve the hydrophobicity of membrane surface, PVDF hollow fiber composite membranes was obtained through the immersion coating of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) dilute solution on the outside surface of PVDF support membrane. The prepared PVDF composite membranes were used in the vacuum membrane distillation (VMD) for the desalination. The effects of PVDF-HFP dilute solution concentration in the dope solution and coating time on VMD separation performance was studied. Membranes were characterized by SEM, WCA measurement, porosity, and liquid entry pressure of water. VMD test was carried out using 35 g.L-1 NaCl aqueous solution as the feed solution at feed temperature of 30 degree(C) and the permeate pressure of 31.3 kPa. The vapour flux reached a maximum when PVDF-HFP concentration in the dilute solution was 5 wt% and the coating time was kept in the range of 10-60 s. This was attributed to the well configuration of micro-nano rods which was similar with the dual micro-nano structure on the lotus leaf. Compared with the original PVDF membrane, the salt rejection can be well maintained which was greater than 99.99 % meanwhile permeation water conductivity was kept at a low value of 7-9 uS.cm-1 during the continuous testing for 360 h.
 
Key Words
    hydrophobicity; PVDF; hollow fiber membrane; vacuum membrane distillation; desalination
 
Address
Hongbin Li, Xingchen Zi, Wenying Shi, Longwei Qin, Haixia Zhang and Xiaohong Qin: School of Textiles Engineering, Henan University of Engineering, 1 Xianghe Road, Zhengzhou 450007, P. R. China
Hongbin Li, Wenying Shi: Collaborative Innovation Center of Textile and Garment Industry of Henan Province, 41 Zhongyuan Road, Zhengzhou 450007, P. R. China
Xiaohong Qin: School of Textiles Science, Donghua University, 2999 North Renmin Road, Shanghai 201620, P. R. China
 

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