Zwitterionic trialkoxysilane compounds were synthesized and used for the modification of PA-TFC reverse osmosis (RO) desalination membranes in order to enhance their performance. The essential of modification is simply based on sol-gel condensation reactions of zwitterionic trialkoxysilanes which were synthesized by the reaction of tert-amine functional trialkoxysilanes and sultones. The membranes were modified by two different methods. In the first one, commercial composite RO membranes (Hydranautics SWC5 40) were coated by zwitterionic silane coupling agents in water at three different concentrations: 1.0, 1.5, and 2.0% (w/v). In the second one, zwitterionic silane compounds were used in the preparation of polyamide active layer of TFC membranes via interfacial polymerization (IP). The silane monomer (SPPT) was added to aqueous m-phenylenediamine (MPD) solution at different concentrations (5%, 10%, 25%, 50%, 75% and 100% of MPD) in order to create interpenetrating polysiloxane-polyamide network during interfacial polymerization on polysulfone support layer (Figure 1). Surface characterization and composition analyses of modified membranes were performed by SEM, XPS, water contact angle (WCA) and zeta potantial measurements. Membrane performances were evaluated by permeability, salt rejection and organic fouling tests. Significant improvements on performances were observed. Figure 2 shows the flux and salt rejection changes of modified membranes by interfacial polymerization. Compared to the control membrane, water flux increased from 25.3 to 33.4 L.m-2.h-1 without loss of salt rejection.

High performance polyamide thin film composite (PA-TFC) desalination membranes modified by zwitterionic silanes

254th National Meeting (2017)

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