Antifungal Polymeric Membranes with Chitosan Functionalized Quaternary Ammonium Salt for Drinking Water Treatment

Abstract

Chitosan was functionalized to synthesize quaternized N-trimethyl chitosan (TMC) and incorporation in polyethersulfone (PES) to fabricate membranes for enhanced antifungal activity and water treatment. The TMC was synthesized from chitosan via reductive alkylation and methylation. The synthesized TMC was characterized mainly through FTIR. Three different concentrations 5, 10 and 15% (w/w) of both chitosan and TMC were taken in casting solution of PES and membranes were fabricated through phase inversion method. The effects of concentration of chitosan and TMC on the properties of functionalized PES membranes were investigated including morphology, water retention, water surface wettability, permeation flux and most importantly antifungal characteristics. The membrane with the lowest concentration of TMC 5% (w/w) resulted in the larger average pore size than the PES membrane with no chitosan or TMC. The contact angle was reduced from 89.67º to 56.78º by increasing concentration of TMC to 15% (w/w). The resultant membranes exhibited improved water hydrophilicity, permeability and inhibition against fungal species. The functionalized membranes had shown noticeable antifungal activity against Aspergillus niger in the case of 15% TMC with 72% antifungal activity and 15% chitosan with 62.5% antifungal activity against Fusarium solani.