Plastic waste-based Cu-BDC and COOH-MWCNT@Cu-BDC MOF for enhancing PPSU membrane for efficient heavy metal removal from industrial wastewater

The rapid expansion of the battery industry, driven by technological advancements and increasing demand for energy storage, presents a significant environmental threat due to the release of heavy metals. This study reports on fabricating a newfangled composite membrane for lead removal as a model contaminant. The new membrane is composed of polyphenylsulfone (PPSU) incorporated with copper-based metal-organic frameworks (Cu-BDC MOFs) and carboxyl-functionalized multi-walled carbon nanotubes (COOH-MWCNT@Cu-BDC). The MOFs were synthesized via upcycling PET plastic waste applying hydrothermal methods. Two types of membranes were developed with varying filler concentrations of 0.05–0.2 wt%, with optimal result at 0.1 wt%. Modified membranes showed improved hydrophilicity, porosity, and mechanical strength. The optimum membrane (PPSU/COOH-MWCNT@Cu-BDC) exhibited superior pure water flux (61 L/m²·h) and Pb²⁺ rejection (99.7 %) compared to pristine membrane (16.25 L/m²·h, 89.3 %). The optimum membrane had high flux recovery ratio (93.5 %), attributed to improved surface morphology and hydration layer formation. With such characteristics, the membrane maintained stable performance (31.25 L/m²·h, 94.15 % Pb²⁺ rejection) in real battery wastewater over 72 h. The study highlights the synergistic effects of Cu-BDC and COOH-MWCNTs in enhancing membrane performance, offering a sustainable and efficient solution for heavy metal removal from wastewater. • Copper terephthalate MOF was successfully synthesised from waste PET. • New filler made of carboxyl-functionalized MWCNT and MOF was prepared. • Prepared filler improved PPSU membrane rejection of Pb. • High flux and Pb rejection were maintained with real industrial wastewater. • Carboxyl group interaction and Cu exchangeability had a vital role in Pb rejection.