Positively charged composite nanofiltration membrane from quaternized chitosan by toluene diisocyanate cross-linking

2-Hydroxypropyltrimethyl ammonium chloride chitosan/polyacrylonitrile (HACC/PAN) positively charged composite nanofiltration (NF) membrane was prepared using HACC as active layer, PAN ultrafiltration (UF) membrane as support layer, and toluene diisocyanate (TDI) as cross-linking reagent. FTIR-ATR spectrum was employed to characterize the cross-linking on the resultant membrane surface. Besides, some characteristics such as the permeability of pure water and the rejection performance to different salt solutions were evaluated. At 20 °C and 30 L h−1 of cycling flow, the permeability of pure water through this membrane was 8.96 kg m−2 h−1 MPa−1. The rejection to different salt solutions increased in the order of Na2SO4, MgSO4, NaCl and MgCl2.