纳滤
膜
海水淡化
离子
化学工程
化学
表面电荷
过滤(数学)
唐南势
微咸水
材料科学
分析化学(期刊)
色谱法
电解质
盐度
电极
统计
工程类
生物
生物化学
物理化学
有机化学
数学
生态学
作者
Haiguang Zhang,Xie Quan,Xinfei Fan,Gang Yi,Shuo Chen,Hongtao Yu,Yongsheng Chen
标识
DOI:10.1021/acs.est.8b04268
摘要
Nanofiltration (NF) is considered a promising candidate for brackish and seawater desalination. NF exhibits high multivalent ion rejection, but the rejection rate for monovalent ions is relatively low. Besides, great challenges remain for conventional NF membranes to achieve high ion rejection without sacrificing water flux. This work presents an effective strategy for improving the ion rejection of conductive NF membrane without decreasing the permeability through electrically assisted enhancement of surface charge density. When external voltage is increased from 0 to 2.5 V, the surface charge density of the membrane increases from 11.9 to 73.0 mC m–2, which is 6.1× higher than that without external voltage. Correspondingly, the rejection rate for Na2SO4 increases from 81.6 to 93.0% and that for NaCl improves from 53.9 to 82.4%; meanwhile, the membrane retains high permeabilities of 14.0 L m–2 h–1 bar–1 for Na2SO4 filtration and 14.5 L m–2 h–1 bar–1 for NaCl filtration. The Donnan steric pore model analysis suggests that the Donnan potential difference between the membrane and bulk solution is increased under electrical assistance, leading to increased ion transfer resistance for improved ion rejection. This work provides new insight into the development of advanced NF technologies for desalination and water treatment.
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