Adsorption of pharmaceuticals onto isolated polyamide active layer of NF/RO membranes. (June 2018)

• Record Type: Journal Article
• Authors: Liu, Yan-ling; Wang, Xiao-mao; Yang, Hong-wei; Xie, Yuefeng F.
• Is Part Of: Chemosphere. Volume 200(2018)
• Page Start: 36
• Page End: 47
• Publication Date: 2018-06
• Subjects: Adsorption -- Polyamide layer -- Trace organic compounds (TrOCs) -- Interactions -- Nanofiltration -- Reverse osmosis. ; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2018.02.088
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Adsorption of trace organic compounds (TrOCs) onto the membrane materials has a great impact on their rejection by nanofiltration (NF) and reverse osmosis (RO) membranes. This study aimed to investigate the difference in adsorption of various pharmaceuticals (PhACs) onto different NF/RO membranes and to demonstrate the necessity of isolating the polyamide (PA) active layer from the polysulfone (PS) support layer for adsorption characterization and quantification. Both the isolated PA layers and the PA+PS layers of NF90 and ESPA1 membranes were used to conduct static adsorption tests. Results showed that apparent differences existed between the PA layer and the PA+PS layer in the adsorption capacity of PhACs as well as the time necessary to reach the adsorption equilibrium. PhACs with different physicochemical properties could be adsorbed to different extents by the isolated PA layer, which was mainly attributed to electrostatic attraction/repulsion and hydrophobic interactions. The PA layer of ESPA1 exhibited apparently higher adsorption capacities for the positively charged PhACs and similar adsorption capacities for the neutral PhACs although it had significantly less total interfacial area (per unit membrane surface area) for adsorption compared to the PA layer of NF90. The higher affinity of the PA layer of ESPA1 for the PhACs could be due to its higher capacity of forming hydrogen bonds with PhACs resulted from the modified chemistry with more –OH groups. This study provides a novel approach to determining the TrOC adsorption onto the active layer of membranes for the ease of investigating adsorption mechanisms. Graphical abstract: Highlights: Polyamide (PA) layers of NF/RO membranes were separated from polysulfone (PS) layers. Adsorption of PhACs onto isolated PA layers was different from that onto PA+PS layers. Positively charged and more hydrophobic PhACs exhibited larger adsorption amounts. The PA layer of ESPA1 had higher affinity for PhACs than the PA layer of NF90.