Closed-Loop Process Design for Destruction and Resource Recovery of Polyethylene Microplastics via Plasma-Assisted Oxidative Gasification

Polyethylene (PE) microplastic remediation requires approaches that address polymer destruction alongside the management of associated contaminants and conversion products. This study proposes an integrated process for PE-equivalent feed conversion and resource recovery, combining plasma-assisted surface activation, oxygen-assisted oxidative gasification, two-stage water-gas shift (WGS), pressure-swing adsorption (PSA), calcium hydroxide-based CO₂ capture, and heavy-metal precipitation, with optional graphene oxide nanofiltration. The connected equilibrium gas phase prediction under vapor only constraint, WGS, and separation stages were modeled in DWSIM, while the plasma, carbonation, and precipitation stages were evaluated through stoichiometric and literature-based calculations. At an equivalence ratio of 0.30 and 773.15 K, the equilibrium gasification model predicted a product gas containing 40.55 mol% CH₄, 29.43 mol% CO₂, 20.57 mol% CO, and 7.38 mol% H2. The idealized PSA-equivalent separation produced a hydrogen rich stream containing 50.36 mol% H₂. Downstream calculations yielded 2.611 kg/s of CaCO₃ and approximately 0.596 g/s of Zn, Cu, and Pb hydroxide precipitates on the selected feed and contamination basis. The summed stage duty was negative under both evaluated plasma-energy scenarios, indicating modeled net thermal release rather than demonstrated electrical power export. The results establish a simulation-based process design framework; experimental validation and further reactor-level and scale-up assessment remain necessary.