Insight into photocatalysis technology as a promising approach to tackle microplastics pollution through degradation and upcycling

Abstract

Due to improper plastic waste handling, microplastics (MPs) have become a serious global problem. MPs threaten animals, plants, and humans as they are passed from one species to another through the food chain. To date, photocatalysis technology has drawn interest as a promising and energy-efficient process to mitigate MPs pollution. Driven by light energy, the photocatalytic process can mitigate MPs pollution in two ways. First, by degrading and mineralizing MPs into CO2 and H2O (referred to as photocatalytic degradation). Second, MPs are treated as low-cost sources to be degraded and converted into valuable products (referred to as photocatalytic upcycling). In this process, the reactive oxygen species (ROSs) are essential in initiating the polymer chain's C[sbnd]C and C[sbnd]H bonds cleavage. The photocatalyst properties and process conditions played a significant role in further optimizing the degradation efficiency and conversion rate. In addition, this review summarized and discussed the recent studies on the photocatalytic degradation and upcycling of MPs and highlighted its mechanism. Lastly, future outlooks were presented to identify the limitations and challenges associated with this process. Overall, this photocatalytic strategy can contribute to the circular economy for plastic waste.