Fabrication of the polysulfone-based composite ultrafiltration membranes for the adsorptive removal of heavy metal ions from their contaminated aqueous solutions

Abstract

The polysulfone-based ultrafiltration membranes were synthesized by the phase inversion method with the varying ratios of composites for the efficient removal of heavy metal ions from their contaminated solutions. The membranes were characterized in terms of porosity, permeability, average pore size, contact angle, zeta potential, flux regeneration, and mechanical strength. The surface morphology of the membranes were analyzed by the field emission scanning electron microscope. The fluxes of the membranes were tested at the different transmembrane pressures of 1.5–3.5 kg cm−2. The lead ion (Pb2+) removal efficiencies of the membranes were investigated for the solutions of initial concentration 50 mg L-1 at a fixed pH value of 5.42. The effect of the feed concentrations on the overall adsorption capacity was investigated by varying the initial feed concentrations from 50 to 200 mg L−1. The highest adsorption capacity was obtained as 279.63 mg g−1 for the feed concentration of 200 mg L−1, and the permeate flux of 1.65 mL min−1. However, the lower feed concentration and the lower flux were advantageous for the long time functioning of the membrane with its higher efficiency without regeneration. The breakthrough curves for the Pb2+ adsorption processes were generated, and the experimental results were compared with the Thomas model. A mixture of heavy metal ions contaminated solutions was passed through the most appropriate membrane (in terms of adsorption capacity) to investigate the effect of co-existing metal ions on the adsorption capacities of lead ions. The removal efficiencies of the membrane for the different metal ions followed the trend like Pb2+ > Cu2+ > Cd2+ > ≈ Fe2+.