Efficient microplastic removal in aquatic environments using iron–nitrogen co-doped layered biocarbon materials

Microplastics (MPs), as an emerging pollutant, are widely distributed in water environments and pose considerable environmental and health threats due to their chemical inertness and the toxicity of attached substances. The development of high-efficient and facile adsorbents for MPs removal is of significance. Hence, this study proposed an innovative iron–nitrogen co-doped layered adsorbent derived from glucose via molten salt-assisted pyrolysis. The presence of molten salt promoted the formation of layered structures, providing micron-scale channels for the entrapment of MPs from water. Loading iron alone enhanced electrostatic adsorption between MPs and carbon materials; however, excessive dosage clogged the channel structure. This can be solved by co-doping nitrogen, which facilitated uniform iron dispersion. The co-doped layered adsorbent with iron loading at 1.43 % achieved a removal efficiency of 96.5 % and capacity of 148.39 mg·g −1 for polystyrene (PS) MPs amid low plastic concentration and adsorbent dosage. It also exhibited efficient removal for a wide pH range and high salinity solution, maintaining over 90 % efficiency after multiple cycles. Kinetic analysis revealed a combined physical and chemical adsorption mechanism. The molten salt-assisted synthesis combined with iron–nitrogen co-doping offers a promising, scalable solution for MPs pollution control, paving the way for the development of highly efficient and reusable adsorbents with enhanced performance in environmental remediation.