MIL-125-NH2/BNQDs persistent photocatalyst enhanced peroxymonosulfate activation for efficient PET plastics removal

Abstract

Polyethylene terephthalate plastic is widely used and poses challenges in degradation, highlighting the importance of finding efficient degradation methods. In this study, MIL-125-NH₂/BNQDs composites were synthesized to degrade polyethylene terephthalate plastic in the peroxymonosulfate-activated persistent photocatalysis system. The results showed that MIL-125-NH₂/2BNQDs exhibited the best degradation effect on polyethylene terephthalate plastic activated by peroxymonosulfate under light conditions, with a degradation efficiency of 95.71 % achieved by adding 3 mM peroxymonosulfate, which was 3.01 times that of MIL-125-NH₂ alone. Furthermore, all composite samples retained persistent catalytic activity under dark conditions after light irradiation. After visible light irradiation, the polyethylene terephthalate degradation efficiency achieved 90.23 % when MIL-125-NH₂/2BNQDs activated by peroxymonosulfate were used under dark conditions. The mechanism of action of reactive radicals in the polyethylene terephthalate degradation process was revealed by scavenger experiments. In-situ X-ray photoelectron spectroscopy analysis demonstrated that MIL-125-NH₂/2BNQDs induce Ti⁴⁺ to Ti³⁺ transition through electron transfer, resulting in higher efficiency of peroxymonosulfate activation. The composites achieve improved electron storage capacity and enhanced peroxymonosulfate activation efficiency. Furthermore, the alteration of valence in transition metals (from Ti⁴⁺ to Ti³⁺) triggers photochromism, which amplifies the ability to absorb light. This study provides new insights for the development of novel photocatalysts for environmentally friendly degradation of polyethylene terephthalate plastics, contributing to the removal of plastic waste and the promotion of resource sustainability