Fouling resistant PVDF/Carboxymethyl chitosan composite nanofiltration membranes for humic acid removal.

In this work, carboxymethyl chitosan without a crosslinking agent was blended with polyvinylidene fluoride using non solvent induced phase inversion process. Carboxymethyl chitosan was synthesized using monochloroacetic acid and isopropanol and its structural elucidation was done. Synthesized carboxymethyl chitosan was incorporated with PVDF and investigated for its casting dope viscosity, x-ray photoelectron spectroscopy, thermal gravimetric analysis, mechanical properties, contact angle, scanning electron microscopy, atomic force microscopy and filtration studies. The designed precipitation kinetics was reflected on these composite membranes by having reduced pore sizes and increased thickness. MWCO was in the range between 600 and 2000 for the composite membranes. Low surface roughness and contact angle favoured the antifouling nature. Irreversible fouling minified as the carboxymethyl chitosan composition increased on the membrane and exhibited excellent mechanical and thermal stability and flux recovery ratio. The membranes were durable after two repeating cycles.