Sustainable preparation of waste expanded polypropylene composites with green-synthesized Ag and graphite-derived carbon: characterization and UV/H₂O₂-assisted dye removal

Abstract

Waste plastics derived from petroleum sources pose a serious global challenge, and their recycling represents an effective strategy from both environmental and economic perspectives. Expanded polypropylene (EPP), widely used in various industrial sectors, is generated in considerable quantities as waste. Waste EPP was functionalized with green-synthesized Ag and thermally processed graphite-derived carbon to prepare flat-sheet composites via thermally induced phase separation (TIPS). The composites were characterized by XRD, SEM, FTIR, and TG-DSC analyses, and their adsorption and UV/H₂O₂-assisted dye removal performances were evaluated using methyl orange (MO) as a model pollutant. Adsorption efficiencies remained limited, reaching 10.5% for Ag-GO-EP and 9.6% for GO-EP. Under the final UV/H₂O₂ conditions, MO removal reached 32.2% for Ag-GO-EP and 30.8% for Ag-EP, with corresponding TOC mineralization values of 24.3% and 22.5%, respectively. Disk diffusion tests showed only limited antimicrobial response against E. coli O157:H7 and S. aureus. Ag-GO-EP maintained its dye removal performance over four consecutive cycles, with a decrease of < 1% between cycles. These findings demonstrate that waste EPP can be converted into stable and reusable functional composites through a simple modification route, providing a potential approach for the functional valorization of polymer waste.