Preparation, characterization and the effect of PANI coated TiO2 nanocomposites on the performance of polysulfone ultrafiltration membranes

Abstract

Polysulfone ultrafiltration (UF) membranes with PANI–TiO₂ (polyaniline–titania) nanocomposites and PEG 1000 (Polyethylene Glycol 1000) as additives were prepared by the phase inversion method. PANI–TiO₂ nanocomposites were synthesized by coating TiO₂ nanotubes with PANI via chemical oxidative polymerization. The synthesized PANI–TiO₂ nanocomposite was characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscope (TEM) analysis. PANI–TiO₂ nanocomposites with varying concentrations (0–1.5 wt%) were dispersed in the polysulfone membrane matrix with N-methyl-2-pyrrolidone (NMP) as solvent along with PEG 1000 as the pore former. The effect of addition of PANI–TiO₂ nanocomposites with different concentrations (0–1.5 wt%) on the membrane structure, performance, hydrophilicity and the antifouling nature of the membranes was analyzed. PANI–TiO₂ nanocomposite membranes showed better hydrophilicity, improved permeability, enhanced porosity, water uptake and good antifouling ability when compared with neat polysulfone membranes. The performance of the membranes improved with the increase in the addition of the PANI–TiO₂ nanocomposite. However, the membrane performance decreased slightly at 1.5 wt% addition of PANI–TiO₂ due to the agglomeration of PANI–TiO₂ at higher concentration. The well performed membranes were also subjected to heavy metal ion rejection. The membranes showed a rejection of 83.75% and 73.41% during the polymer enhanced ultrafiltration (PEUF) process and a rejection of 68% and 53.78% during the UF process for Pb²⁺ and Cd²⁺ respectively.