High flux zwitterionic hybrid cellulose acetate desalination membranes: Formation of permeability-effective macropores by self-organizing zwitterionic silanes br

Zwitterionic hybrid cellulose acetate membranes with improved flux and antifouling performance were produced by a modified non-solvent induced phase separation (NIPS) process in which a zwitterionic trimethoxysilane compound, (3-sulfopropylbetaine-propyl)-trimethoxysilane (SPPT), was added to the casting solutions at 1.0, 2.0, and 3.0 wt%. The successful incorporation of SPPT into cellulose acetate (CA) membranes was proved by X- ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and thermal gravimetric analysis (TGA). Permeate fluxes of the hybrid membranes increased significantly compared to the control cellulose ac-etate membrane prepared without the addition of SPPT (15 bar pressure; 2000 ppm NaCl or MgSO4 aqueous solution filtration). The hybrid membranes exhibited an increase in permeate flux up to 87 % while their salt rejections slightly decreased in NaCl solution filtration. In MgSO4 solution filtration, the flux was increased by 61 % without sacrificing salt rejection. The reason for the enhancement in the flux was the formation of macropores in the membrane bulk structures by self-organizing zwitterionic silane groups. The highest resistance to bovine serum albumin (BSA) or xanthan gum as a foulant was observed in the hybrid membranes produced with 1.0 wt % of SPPT