Preparation and characterization of composite NF membrane from a graft copolymer of trimethylallyl ammonium chloride onto chitosan by toluene diisocyanate cross-linking

A novel positively charged composite NF membrane was prepared using a copolymer graft of trimethylallylammonium chloride onto chitosan (GCTACC) as the top selective layer, a poly(acrylonitrile (PAN) ultrafiltrationmembrane as the support layer and toluene diisocyanate (TDI) as the cross-linking reagent. The effects of membranepreparation conditions on membrane performance were investigated such as TDI concentration, GCTACCconcentration, etc. The observation from scanning electron microscopy suggested the composite structure of theresultant NF membrane. At 20 and 30 L.h−1 of cycling flow, the permeability of pure water was 14.1 kg.h−1.m−2.MPa−1. The order of rejection to different salt solutions was MgCl2> MgSO4> NaCl > Na2SO4, revealing thecharacteristic of positively charged NF membranes.