Modification of forward osmosis membrane with naturally-available humic acid: Towards simultaneously improved filtration performance and antifouling properties. (October 2019)

• Record Type: Journal Article
• Authors: Guan, Yan-Fang; Huang, Bao-Cheng; Wang, Yun-Jie; Gong, Bo; Lu, Xinglin; Yu, Han-Qing
• Is Part Of: Environment international. Volume 131(2019)
• Publication Date: 2019-10
• Subjects: Thin-film composite membrane -- Humic acid -- Permeability -- Selectivity -- Anti-fouling; Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2019.105045
• Languages: English
• ISSNs: 0160-4120

Abstract

Abstract: In this work, a thin-film composite forward osmosis (FO) membrane was fabricated on polyethersulfone substrate by interfacial polymerization with naturally-available humic acid (HA) as a stable membrane additive in the support layer. Compared with the pristine polyethersulfone substrate, the incorporation of HA significantly altered the cross-section structure, increased average pore size and porosity of the substrate, leading to a thinner polyamide layer, further increasing the water flux (permeability). Specifically, the FO membrane showed a higher water flux (~20 L m − 2 h − 1 ) with the introduction of HA than the membrane synthesized without HA (~15 L m − 2 h − 1 ) in the FO mode with 2 M NaCl as draw solution. Moreover, the selectivity of the membrane was improved ~45% by dosing 0.8 wt% HA into the substrate, in comparation to the pristine membrane without HA doped. Besides, the average roughness of the polyamide layer was reduced by up to 68% when HA was present in the substrate, which mitigated the fouling potential. Thus, a slower flux decline ratio (~60%) was observed for the membrane modified with 0.8 wt% HA than the pristine membrane (~80%). Taken together, our findings shed light on using natural-available HA for effectively and efficiently modifying membrane substrate to simultaneously enhance the permeate-selectivity performance and the anti-fouling behavior in FO membrane process. The fundamental causes of these differences in membrane separation performance and fouling behavior are considered and related to the physical and chemical characteristics of support layer (i.e., porosity and pore size) and polyamide layer (i.e., active layer thickness and roughness) of membranes. Graphical abstract: Unlabelled Image Highlights: FO membrane with high water permeability was fabricated by doping HA. Porous structure of substrate was altered after doping HA. Hydrophilicity of polyamide layer was enhanced with dosing of HA. Anti-fouling performance of the FO membrane was improved.