A review of microplastic surface interactions in water and potential capturing methods

Microplastics are emerging micropollutants in water threatening aquatic and land organisms. The microplastic–water system is complicated due to the multiple constituents in the water system and the minuscule size of the plastic waste. Although typical plastic-based materials are inert, the behavior of fragmented plastics is arbitrary and indefinite. When exposed to erratic water environments with the presence of organic and synthetic impurities, pH, temperature, and salt, microplastic surfaces may be potentially active and generate charges in water. These phenomena determine microplastics in water as a colloidal system. The classical Derjaguin Landau Verwey and Overbeek (DLVO) theory can be used to identify the microplastic surface behavior in water. The modification of microplastic surfaces eventually determines the overall interactions between microplastics and other constituents in water. Moreover, the geometry of microplastics and additives present in microcontaminants play a crucial role in their net interactions. Hence, multiple microplastic removal techniques, such as coagulation, filtration, and air flotation, can be developed to address the issue. In many cases, a combination of these methods may be needed to achieve the overall procedure in water treatment plants or generic water systems. Selection of an appropriate microplastic removal technique is crucial and should be based on the water environment and the intended use of the water to ensure its safety.