Biochar as adsorbents for environmental microplastics and nanoplastics removal

Amid escalating global concerns regarding plastic pollution, a multitude of strategies for the removal of microplastics and nanoplastics (MPs/NPs) have been rigorously explored. Biochar, distinguished by its elevated specific surface area, complex porosity, and robust stability, has emerged as a promising candidate for the adsorption of MPs/NPs from the environment. This review introduces biochar modification techniques to augment the adsorption capabilities of biochar-based adsorbents, encompassing acid/base modification, metal modification, ball milling modification, and surfactant modification. The mechanisms of MPs/NPs adsorption by biochar are discussed in detail. Besides, the influence of environmental factors on the adsorption behavior of biochar adsorbents is also analyzed. Lastly, future research directions and innovative strategies are proposed aiming to provide comprehensive assistance in exploring the potential applications of biochar. In addition to pursuing enhanced removal efficiency of MPs/NPs through biochar, the challenges of biochar regeneration and substance leaching are also discussed by introducing constructive strategies, such as constructing catalytic degradation systems and enhancing adsorbent stability through calcination, to bolster the sustainability of biochar-based environmental remediation approaches. Conclusively, biochar presents a significant avenue for the environmental amelioration of MPs/NPs, with its deployment in environmental stewardship warranting deeper exploration.