Porogen- and fluorine-free superhydrophobic monoliths derived from waste plastics for oil spill and microplastic remediation

Oil spill accidents and the increasing accumulation of waste plastics and microplastics have posed significant environmental challenges globally. In this study, an inexpensive and facile chemical recycling thermally induced phase separation (TIPS) technique was employed to fabricate monoliths from waste plastics. The porogen- and surface modification (fluorine)-free porous superhydrophobic (SHP) monoliths were prepared from waste plastics. The substantial hydrophobic functional groups present on the polymer surfaces combined with the irregular stacking of polymer flakes that generates hierarchical surface roughness. The as-developed monoliths were demonstrated water contact angles (WCA) more than 152° with rolling angles (RA) less than 5° and oil contact angles (OCA) nearly 0°. To assess the effectiveness of SHP monoliths, a thorough investigation was conducted on their ability to remove microplastics, absorb oil pollutants, and separate water-in-oil emulsions. The SHP monoliths were showed exceptional absorption capacities toward various organic solvents, while maintaining their effectiveness more than 15 absorption cycles. In addition, the prepared monoliths were demonstrated separation efficiencies over 99% for oil-water mixtures and retained their effectiveness after 10 cycles. They also efficiently separated surfactant-stabilized water-in-oil emulsions, oil content from harsh environment and effectively removed microplastics from aquatic environments. Moreover, they sustain their superhydrophobicity even after 15 abrasion cycles and 48 h immersion in different pH solution. This approach for recycling waste plastics into SHP monoliths offers strong potential for scalable environmental remediation applications.