Hybrid PVC/EDTA-Bentonite ultrafiltration membranes for efficient Pb (II) removal from wastewater

Hybrid ultrafiltration membranes were prepared by incorporating ethylenediaminetetraacetic acid (EDTA)-modified bentonite nanoparticles into a poly (vinyl chloride) (PVC) matrix via a non-solvent induced phase separation (NIPS) process. The EDTA-bentonite filler was designed not only as a hydrophilic clay additive but also as an active chelating phase for dissolved Pb²⁺ ions. The structure and properties of the resulting mixed-matrix membranes were examined using FTIR, XRD, Raman spectroscopy, FESEM, AFM, contact angle measurements, and mechanical testing. An intermediate filler loading produced a more hydrophilic and porous morphology with improved tensile strength, demonstrating that the modified clay can simultaneously tune both transport and mechanical behavior. Filtration experiments with Pb²⁺ solutions showed that the optimized membrane achieved high lead rejection (99%) and significant adsorption capacity, with equilibrium data well described by the Langmuir isotherm, consistent with monolayer chemisorption on EDTA sites. The mechanistic analysis indicates that Pb²⁺ removal is dominated by chelation and ion exchange on the EDTA-functionalized bentonite dispersed throughout the PVC matrix, rather than by size-exclusion alone. Because the membrane is fabricated from commodity PVC, naturally abundant bentonite, and a simple EDTA modification step, the proposed system offers a stable, scalable, and low-cost platform for heavy-metal removal from contaminated waters.