Metal-Modified Biochar: A Sustainable Approach for Microplastics Removal from Drainage Water

Environmental pollution from heavy metals, dyes, and emerging contaminants such as microplastics has prompted the exploration of low-cost, sustainable adsorbents. Biochar, derived from biomass pyrolysis, has emerged as a promising candidate due to its porous structure, surface functionality, and potential for chemical modification. This paper aims to review the current strategies employed in the synthesis and modification of biochar-based composites and assess their efficiency in environmental remediation applications. A comprehensive literature review was conducted, emphasizing recent developments in biochar modification techniques including metal impregnation, clay integration, hydrothermal processing, and mechanochemical treatments. Modified biochars showed substantial improvement in adsorption performance compared to their pristine forms. For heavy metals, Fe-impregnated biochar achieved Pb(II) removal efficiencies exceeding ۹۵% with adsorption capacities up to ۱۲۳.۴ mg/g. MgO-doped biochar exhibited a methylene blue dye removal capacity of ۲۱۶.۷ mg/g. In microplastic remediation, Fe–Mn-modified biochar demonstrated an adsorption capacity of ۳۴.۲۹ mg/g and removal efficiency of ۸۸% for polystyrene microplastics under optimized conditions (pH ۷, ۲۵°C). Ball-milled biochar composites achieved up to ۳-fold increases in surface area and enhanced metal–carbon interactions, leading to higher adsorption via hydrophobic, electrostatic, and π–π interactions. Metal oxide-loaded biochars consistently outperformed pristine biochars, particularly in systems with electrostatic or ion-exchange dominant sorption mechanisms. Biochar-based composites present a versatile and effective platform for environmental remediation. Their performance depends strongly on synthesis parameters and functional modifications. Integration of metals, oxides, and structural tailoring can significantly enhance sorption capabilities, making them viable alternatives to conventional adsorbents.

کلیدواژه ها:

Environmental remediation ، Sustainable treatment ، Microplastics ، Adsorption ، Hydrophobic