Roles of microplastic-derived dissolved organic matter on the photodegradation of organic micropollutants

Microplastic-derived dissolved organic matter (MP-DOM) is ubiquitous in water environment and exhibits photosensitivity. However, little is known about the effects of MP-DOM on the photodegradation of organic micropollutants in natural water. In this study, we investigated the effect of MP-DOM derived from two typical plastics, i.e., polystyrene (PS), and polyethylene (PE), on the photodegradation of a typical organic micro -pollutants sulfamethoxazole (SMX) in a simulative natural water system. MP-DOM exerted a significant inhi-bition on the SMX photodegradation, mainly attributed to the direct photolysis inhibition of SMX caused by the inner filter effect and the complexation effect. Despite the enhanced reactive oxygen species (ROS) generation with the increase of their steady-state concentration by 41.1 -160.7 %, PS-DOM exhibited high oxidation resistance, causing an inhibition on the photodegradation of SMX probably through transferring electrons to the SMX intermediates. This study helps to deepen the understanding of microplastic photochemical behavior in natural water.

Automated summary

In this study, the researchers investigated the impact of microplastic-derived dissolved organic matter (MP-DOM) on the photodegradation of organic micropollutants in natural water. It was found that MP-DOM significantly inhibited the photodegradation process, primarily due to the inner filter effect and complexation effect. Furthermore, the researchers observed that polystyrene-derived dissolved organic matter (PS-DOM) exhibited high oxidation resistance, leading to the inhibition of photodegradation by transferring electrons to the intermediates.