Synthesis, characterization of polyelectrolyte and performance evaluation of polyelectrolyte incorporated polysulfone ultrafiltration membrane for metal ion removal

Abstract

Poly 6-methyl 2-vinyl pyridinium sulphate (PMVPS) cationic polyelectrolyte was successfully synthesized from 2,6-lutidine. The structure of the compound was elucidated by IR, NMR and mass spectral analysis. The polyelectrolyte incorporated polysulfone ultrafiltration membrane (PSf/PMVPS) was prepared by the phase inversion in a wet process. The membranes were characterized by attenuated total reflectance Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy. Also, contact angle, pure water flux, water content, membrane hydraulic resistance, porosity and molecular weight cut-off were investigated for the influence of PMVPS. The SEM analysis revealed that the PSf/PMVPS membrane has typical asymmetric structure. The X-ray photoelectron spectroscopic (XPS) analysis has shown enrichment of PMVPS on the membrane surface. The membranes showed a decrease in mean surface-pore size, and increase in overall porosity and the hydrophilicity with the increase in PMVPS content. The removal of heavy metal ions such as copper, nickel, lead and cadmium using modified PSf membranes from aqueous solutions has been systematically investigated. Attempts have been made to correlate the performance of the membranes with their morphology. The modified membranes exhibit excellent separation properties with high permeabilities at low trans-membrane pressures. The removal of dissolved metal ions is more by polyelectrolyte enhanced structure than PSf membrane.