Harnessing plastic waste for sustainable membrane filtration with trimodal structure through acid-catalyzed oxidation

Polyolefin waste is among the most generated yet least recycled. Despite its potential as a feedstock of superhydrophobic membranes for organic solvent filtration, it remains a challenge to achieve high selectivity and permeability for viscous oils. In this study, we valorized polyolefin waste into trimodal water filtration membranes through acid-catalyzed oxidation and a void inducer. This approach enabled the creation of membranes with exceptional wettability and strength, characterized by a combination of micropores, macrovoids (30-70 mu m), and cavities (150-200 mu m). The acid-catalyzed oxidation introduced oxygen moieties into the membrane structure, resulting in a reduced water contact angle, improved hydrophilicity, and increased permeability. The micropores facilitated capillary action, macrovoids enabled efficient water passage, and cavities acted as oil reservoirs, for optimal oil-water separation. Various membranes were synthesized using low-density and highdensity polyethylene (PE), polypropylene (PP), and their blend. The obtained results were compared with commercial membranes, revealing a flow rate of 43 ml/min, a retention capacity of 261 mg, and an oil removal efficiency ranging from 84-94 %. Furthermore, the membranes exhibited recyclability, demonstrating stability over at least 10 cycles. This hybrid process transforms plastic waste into trimodal water filtration membranes, achieving a balance between superoleophilicity and hydrophilicity.