Preparation, characterization and humic acid removal capacity of chitosan coated iron-oxide- polyacrylonitrile mixed matrix membrane

Abstract

Flat sheet mixed-matrix membranes (MMM) were cast using amine stabilized iron oxide nanoparticles (Fe₃O₄) and polyacrylonitrile (PAN) coated with chitosan. The effects of iron oxide impregnation (Fe₃O₄) and chitosan coating on removal of humic acid were investigated. The cast membranes were characterized by scanning electron microscopy (SEM), permeability, molecular weight cut off (MWCO), pore size, hydrophilicity, mechanical strength, Fourier transform infrared spectroscopy (FTIR), zeta potential, surface area and surface roughness. Mechanical strength and zeta potential of MMM increased (more positively charged) with Fe₃O₄ concentration. SEM images confirmed that MMM became denser with Fe₃O₄ impregnation. Adsorption of humic acid on MMM was quantified and Langmuir isotherm was fitted. The adsorption of HA by MMM was also confirmed by FTIR. The long term stability of MMM was investigated in a cross flow filtration unit. Effects of various operating conditions like transmembrane pressure, cross flow rate and feed concentration on membrane performance were also investigated. Atomic force microscopy (AFM) showed that, surface roughness of membrane was reduced with nanoparticles impregnation. Flux recovery ratio (FRR) also confirmed the antifouling nature of MMM.