Effects of polypropylene microplastics on multiple sulfonamide removals by the Fenton process

Abstract

We investigated the effects of polypropylene microplastics (MPPs) on removing four sulfonamide antibiotics (SAs) through the Fenton process. The interference of MPPs on SAs removal highly depended on the attached ions and polar groups. While the original MPPs showed a negligible effect, MPPs pre-treated with Na2S2O3, NaClO, NaOH, NaHCO3, FeSO4, Fe(NO3)3, methanol, tert-butanol, humic acids, O3, and UV inhibited the removal ratio by 11% to 70% due to the consumption of hydroxyl radicals by the aged MPPs. H2SO4-treated MPPs promoted 9% SAs removals due to increased adsorption removal. The Fenton process destroyed MPPs, releasing small molecules and increasing the dissolved organic carbon by 20%. The fragmented MPPs adsorbed Fe3+, SAs, and intermediates of SAs. Fragmentation and polar groups significantly increased, resulting in new hazards after the Fenton process treatment. MPPs increased the difficulty of SAs removal, making the treated solution and MPPs potentially hazardous.