Efficient degradation of polystyrene microplastics in aquatic systems via plasma activated water: Mechanistic insights, life cycle assessment, and environmental safety evaluation

Microplastics in aquatic systems demand treatments that are efficient, environmentally compatible, and scalable. An 81.8 % removal efficiency for PS-MPs was obtained in 2 h using PAW at an initial concentration of 1 g/L. In-situ EPR/chemical probes and OES establish an interfacial radical environment, while hybrid DFT—anchored to these measurements—identifies benzylic hydrogen abstraction by •OH, followed by peroxidation and β-scission, as the kinetically favored backbone-cleavage sequence. Finite-element field simulations resolve high-field hotspots at the needle apex and rationalize interfacial radical flux. Multiscale characterization (SEM, FTIR/UV–Vis, TOC, Mw) shows a staged evolution from surface roughening to oxidative chain scission and release of low-molecular-weight products confirmed by GC–MS. Time-resolved ecotoxicity indicates that extended treatment reduces acute responses and yields effluents with low toxicity to Chlorella vulgaris and Vigna radiata; some products are microbially utilizable. Life-cycle assessment shows a lower carbon footprint than photocatalysis and activated-carbon adsorption for an equivalent functional unit; techno-economic analysis indicates favorable cost trajectories with continuous-flow operation and renewable electricity. Together, these results establish an integrated reactor–molecule–system framework for plasma remediation and provide actionable levers (electrode geometry, gap/flow, energy supply) for translating PS-MP degradation to environmentally relevant conditions.