Chitosan-based thin active layer membrane for forward osmosis desalination.

A novel hydrophilic chitosan-based thin active layer membrane was elaborately fabricated through a facile method and its performance was studied in forward osmosis (FO) desalination process. Chitosan (CS) was interfacially polymerized with trimesoyl chloride (TMC) monomer on the surface of sulfonated polyethersulfone-polyethersulfone (SPES-PES) support layer. Two different procedures were employed to incorporate CS into the membrane thin active layer structure. The solutions containing different CS concentrations (from 0.5 to 2.0wt.%) were firstly loaded on the support layer surface, treated in the presence and absence of NaOH solution. The novel CS based membranes were then prepared via addition of TMC solution with appropriate concentration. Compared to commercial thin film composite (TFC) membrane, the modified membrane with an optimal CS concentration demonstrated remarkably higher hydrophilicity and water permeation. The results indicated that the NaOH treatment and higher CS concentration led to form a dense thin active layer, improving membrane performance in salt rejection.