Heavy metals remediation using MOF5@GO composite incorporated mixed matrix ultrafiltration membrane

Abstract

A polysulfone-based mixed matrix membrane (MMM) was prepared by incorporation of MOF5@GO composite in the polymer matrix. The prepared membrane was characterized by permeability, scanning electron microscopy, Fourier transform infrared spectroscopy, zeta potential, X-ray photoelectron spectroscopy, atomic force microscope, molecular weight cut-off and average pore radius. MMM exhibits enhanced permeability, pore size, surface roughness and molecular weight cut-off compared to polysulfone membrane. Pure water permeability of M−0.5 enhanced from 37.9 to 59.5 L/m2h.bar, which corroborated an increase in molecular weight cut-off from 46.9 to 74.1 kDa and pore radius from 66.9 to 75.4 Å as MOF5@GO composite was incorporated in polysulfone polymer matrix. At neutral pH, the optimized MMM (M−0.5) shows –22.7 mV zeta potential facilitating the adsorption of heavy metals. The M−0.5 membrane exhibits 95–99 % rejection of Pb, Cu, Zn and Cd at 2 bar pressure with enhanced permeate flux (∼116 L/m2h) compared to the polysulfone membrane. M−0.5 membrane shows better antifouling properties than the polysulfone membrane. Among the heavy metals studied, lead and copper showed the maximum rejection. The MMM shows 99 % rejection of lead and copper and breakthrough time of 12 and 9 h, respectively for a small membrane area (0.0012 m2). Thus, the prepared low-pressure driven mixed matrix ultrafiltration membrane was suitable and competent for heavy metal rejection. A modified convection-adsorption model based on the first principle was used to predict the long-term filtration performance of the membrane. The same model was used to generate the performance curve for scaling up the process.