Biodegradation and catalytic-chemical degradation strategies to mitigate microplastic pollution

Plastics are essential raw materials widely used in various fields in our modern society due to their excellent durability, moldability and lightweight. Nevertheless, the massive amount of non-biodegradable plastic waste has caused widespread pollutions of the environment. Especially, the microplastics (MPs) with diameters less than 5 mm have recently been recognized as an emerging kind of pollutant on the planet. MPs are carriers of heavy metals and persistent organic pollutants (POPs) and can be transmitted along the food chains simply by ingestion of organisms. A continuously increasing number of researches about MPs have been reported during the last decade, indicating the importance of this field. The majority of the known reports (~93%) focus on understanding the key fundamental questions from the perspective of environmental science, such as the geographical distribution, migration path, origins of their formation and ecological absorption effects, etc. To solve the MPs issue, it is highly essential to look for degradation strategies from the perspective of material science and chemistry, more specifically to effectively mitigate the generation and to reduce the potential harms of these pollutants. In this review, very recent progresses of degrading MPs by either biodegradation or catalytic-chemical degradation are summarized. The degradation mechanism, degradation end-products and the pros and cons of each method are systematically discussed. The challenges and the application potentials of both methods will also be discussed to shed light on evoking effective degradation strategies to solve the problem of MPs.