Understanding the Adsorption Behavior of Heavy Metals onto the MPs and Their Impact

Microplastics (MPs) contamination of soils and streams is a growing global environmental problem. Environmental heavy metals (HMs) are transported by "minor but effective" vectors and carriers, known as MPs, and are widely distributed in freshwater and marine systems. To determine the transportation, fate, and environmental impact of HMs, it is essential to comprehend their adsorption behaviors onto MPs. Physical and chemical characteristics including surface (chemistry and area) and the presence of functional groups on MPs surfaces essentially control the HMs’ adsorption onto them. Electrostatic interactions, exchange of ions, surface complexation, and coordination bonding are a few examples of adsorption mechanisms. The adsorption process is influenced by the type and concentration of HMs together with aqueous solution factors (such as temperature, pH, salinity, DOM, and particular matter). Beyond their transit in aquatic systems, HM adsorption onto MPs has a significant influence. The fate and behavior of MPs may change as a result of the adsorbed HMs, which may have an impact on their bioavailability and ecological effects. Furthermore, as MPs can be consumed by a variety of organisms and move up the food chain, the presence of HMs on them might result in secondary contamination. This book chapter also examines the difficulties in characterizing MP surfaces, the intricate interactions between various contaminants, and the requirement for standardized procedures for analyzing the adsorption of HMs onto MPs. Additionally, the possible environmental dangers and ecological effects brought on by MPs loaded with HMs are emphasized, highlighting the significance of additional research in this area.