Enhancing Pb(II) Removal Efficiency Using Polyethersulfone/core–shell-Fe₃O₄/ZnO Nanofiltration (NF) Membranes

The modification of nanofiltration membranes plays a significant role in the performance of membranes for synthetic and environmental water samples. Specifically, varying the addition of monomers during the interfacial polymerization process enhances the permselectivity of heavy metal removal from water samples. Lead is one of the naturally occurring heavy metals utilized by many industries; however, its presence in water has harmful effects for the environment and human health. Therefore, the removal of Pb(II) from water is a critical societal concern. In this study, the addition of trimesoyl chloride (TMC) with different concentration loadings (0.1, 0.2, and 0.3 w/v%) was varied to enhance the morphological architecture, surface roughness, hydrophilicity, and permselectivity of the membranes. The enhanced morphological structure illustrated from the Scanning Electron Microscopy images elucidates the role of TMC addition. The Fourier Transform Infrared spectra confirmed the successful formation of nanofiltration membranes through the presence of amine and acyl chloride groups. Performance studies illustrated that NF3 (0.1 w/v% of TMC) achieved an optimal removal of salt rejections, with a removal efficiency of 50.91% for Na₂SO₄ and 12.67 % for MgCl₂ attributed to charge density and pore structure. Furthermore, NF3 showed the enhanced adsorption rate of Pb(II) removal attributed to the synergistic Donna exclusion effect and tailored surface chemistry. The maximum Langmuir adsorption capacity of NF3 was 8.8573 mg/L. Therefore, the tailored adsorptive PES/core–shell-Fe₃O₄/ZnO nanofiltration membranes showed an 87.09% Pb(II) removal efficiency, showing significant potential for removing other competing ions from environmental wastewater.