Efficient removal of lead ions from aqueous solution by graphene oxide modified polyethersulfone adsorptive mixed matrix membrane.

In this study, we report the combined effect of graphene oxide (GO) and polyvinylpyrrolidone (PVP) for the heavy metal removal efficiency of polyethersulfone (PES) membranes. PVP with four different amounts of GO was infused in the membrane matrix by the physical blending method. Characterizations such as porosity, contact angle, water flux and Fourier transform infrared spectroscopy were conducted for all prepared membranes. Viscid behavior of polymer dope solution was examined to understand the phase separation phenomena better. PVP enhanced the GO distribution within the membrane surface to some extent via hydrogen bond. The addition of nanoparticles enhanced the membrane physicochemical properties with water permeation, Pb2+ rejection and adsorption capacity. Permeate flux of modified membrane (m4) was found to be 150.21 L/m2h and it is 8.03 times higher than unmodified membrane (m0). Besides, all fabricated membranes were evaluated for Pb2+ rejection from synthetic wastewater and rejection % of m4 (80.6%) had increased twofold than m0 (38.9%). Membrane cleaning was performed using different methods and the best results were achieved with a concentration of 0.05 wt% sodium hypochlorite under pH 7 and further reused for the filtration test. Moreover, adsorption isotherm was tested using Freundlich and Langmuir models and the Langmuir model offered the best fitting.

Exfoliated hydrotalcite-modified polyethersulfone-based nanofiltration membranes for removal of lead from aqueous solutions.

In recent years, the volume of wastewater produced worldwide has led to an increase in the study and use of different membranes and their properties. The progress of membrane technology in hand with nanotechnology has brought to the establishment of advanced membrane materials that are effective in the field of wastewater treatment and water reclamation. This study focuses on the effectiveness of exfoliated hydrotalcite (EHT) nanosheets in the membrane structure which has been evaluated by water flux and heavy metal rejection studies from aqueous solutions. Moreover, the shedding of HT in an organic polar solvent provides a new type of 2-D nanosheet with higher positive charge density. Hydrophilicity, porosity, surface and cross-section morphology, functional groups, and mechanical strength are determined to characterize the prepared membranes. The effect of adding a pore-forming agent to the dope solution is also investigated. Increased hydrophilicity of the modified membranes is confirmed by water contact angle measurement. Furthermore, EHT is found to be an efficient inorganic additive to get better membrane performance and can be employed as a promising candidate for the removal of Pb2+. The rejection % enhanced substantially (50.2% as compared with 29.5% for PES membrane) with increased loading of EHT up to 0.5 g.