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Transport of trace organic compounds through novel forward osmosis membranes: Role of membrane properties and the draw solution
Water Research ( IF 12.8 ) Pub Date : 2018-05-05
Marc Sauchelli, Giuseppe Pellegrino, Arnout D'Haese, Ignasi Rodríguez-Roda, Wolfgang Gernjak

Forward osmosis (FO) offers to be a very promising technology for the removal of trace organic compounds (TrOCs) from contaminated wastewater, and with the recent developments in FO membranes, the effect of both a higher water flux and reverse salt flux on the rejection of TrOCs needs to be explored. In this study two novel thin-film composite (TFC) membranes with greater water permeability and selectivity than the benchmark cellulose tri-acetate (CTA) membrane were compared at bench-scale in terms of TrOCs permeability. By probing the solute-membrane interactions that dictate the transport of TrOCs through the two membranes in the absence and presence of a draw solution, several conclusions were drawn. Firstly, steric hindrance is the main TrOCs transport -limiting mechanism through TFC membranes unless the negative membrane surface charge is significant, in which case, electrostatic interactions can dominate over steric hindrance. Secondly, the increase in ionic strength induced by the draw solution in the vicinity of and perhaps inside the membrane seems to favour the rejection of TrOCs by “shrinking” the membrane pores or by “shielding” the negative surface charge. Lastly, during FO operation, solute concentration polarisation becomes detrimental when working at high water fluxes, whereas the reverse solute flux has no direct impact on the transport of TrOCs through the membrane.



中文翻译:

微量有机化合物通过新型正向渗透膜的运输:膜性能和汲取溶液的作用

正向渗透(FO)对于从受污染的废水中去除痕量有机化合物(TrOCs)而言是一项非常有前途的技术,并且随着FO膜的最新发展,较高的水通量和反向盐通量对废品率的影响TrOC的数量需要探索。在这项研究中,两种新型的薄膜复合(TFC)膜的透水性和选择性均高于基准三醋酸纤维素(CTA)膜,并在试验规模上对TrOCs的渗透性进行了比较。通过探测在不存在和存在牵引溶液的情况下决定TrOCs通过两层膜运输的溶质-膜相互作用,得出了一些结论。首先,空间障碍是通过TFC膜的主要TrOCs输运限制机制,除非负膜表面电荷显着,在这种情况下,静电相互作用可占主导地位。其次,通过在膜附近甚至在膜内部的汲取溶液引起的离子强度的增加似乎通过“收缩”膜孔或“屏蔽”负表面电荷而促进了TrOCs的排斥。最后,在FO操作过程中,当在高水通量下工作时,溶质浓度极化变得有害,而反向溶质通量对TrOCs通过膜的传输没有直接影响。通过在膜附近甚至在膜内部的汲取溶液引起的离子强度的增加似乎通过“收缩”膜孔或“屏蔽”负表面电荷而促进了TrOCs的排斥。最后,在FO操作过程中,当在高水通量下工作时,溶质浓度极化变得有害,而反向溶质通量对TrOCs通过膜的传输没有直接影响。通过在膜附近甚至在膜内部的汲取溶液引起的离子强度的增加似乎通过“收缩”膜孔或“屏蔽”负表面电荷而促进了TrOCs的排斥。最后,在FO操作过程中,当在高水通量下工作时,溶质浓度极化变得有害,而反向溶质通量对TrOCs通过膜的传输没有直接影响。

更新日期:2018-05-05
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