Repurposing disposed surgical face masks into activated carbon for efficient sorption of bio recalcitrant malathion pesticide

Abstract Pesticides are essential for enhancing agricultural produce, but their excessive use poses risks to ecosystems due to persistence and toxicity. This study explores repurposing disposed surgical face masks (DSFMs), rich in polypropylene (PP), as a precursor for activated carbon (AC) synthesis, addressing plastic pollution. DSFM pieces was subjected to hydrothermal treatment with sulfuric acid and KOH activation, optimized via response surface methodology (RSM). Optimal AC preparation conditions were achieved at 800°C, PP/KOH ratio 3 g/g, and 50 min resulting in AC (3AC800-50) with BET surface area 892.16 m²/g and pore volume 0.6353 cm³/g. The resulting carbon material demonstrated excellent adsorption affinity towards malathion pesticide (MP) with a capacity of 536.68 mg/g. Adsorption isotherm experiments indicated favorable processes, validated by the Langmuir isotherm parameter RL values below 1. The Freundlich adsorption model accurately fit the data with high R2 of 0.9898. Kinetic analysis revealed the pseudo-second-order (PSO) model as the best fit, with negative ∆G° indicating the spontaneous nature of MP adsorption. These findings highlight the potential of utilizing ACs derived from DSFMs for sustainable plastic waste management and pesticide removal from water.