Valorisation of waste polyethylene sachets into low-cost reusable oil sorbents: Mechanical modification, process...

Crude oil spills remain a persistent global environmental challenge, while polyethylene (PE) waste continues to accumulate, particularly in low-resource settings. This study develops a circular-economy approach that directly addresses both issues through the valorisation of post-consumer PE water sachets into effective, low-cost sorbents for oil spill remediation. Waste PE was mechanically processed and modified via NaCl-assisted abrasion to produce shredded polyethylene (S-PE) and surface-roughened polyethylene (SR-PE). Characterisation by scanning electron microscopy (SEM) confirmed increased surface roughness and microcavity formation, while Fourier-transform infrared spectroscopy (FTIR) indicated minor surface oxidation following abrasion. Response surface methodology and I-optimal design were used to evaluate the effects of sorbent type, particle size, sorbent dose, and oil loading. Sorbent morphology was the dominant performance factor, with SR-PE achieving oil uptake capacities of approximately 8 g/g for synthetic crude oil and 5.9 g/g for natural crude oil under optimised conditions using a 5 min operational contact time. Natural crude oil adsorption showed reduced sensitivity to operating conditions, indicating robust performance across the investigated conditions. Regeneration studies showed an initial decline followed by stabilisation of adsorption capacity, demonstrating sustained multi-cycle performance. A techno-economic assessment based on stabilised reuse performance estimated lifecycle oil-removal costs of 0.042-0.130 USD/kg oil, lower than representative literature-based estimates for commercial polypropylene sorbents. Overall, the integration of simple material modification, statistical optimisation, regeneration, and economic assessment demonstrates the potential of recycled PE as a reusable, low-cost sorbent for oil spill remediation.