Biochar: a potential and green adsorbent for antibiotics removal from aqueous solution

Antibiotics like tetracyclines, quinolones, sulfonamides, and beta-lactams are commonly used in human and animal health. They have been widely detected in aquatic environments, with concentrations reaching several mg/L. Due to their persistence and resistance to natural degradation, this can lead to severe environmental issues (e.g., resistance genes, resistant bacteria). Consequently, there is an urgent need to remove them from water. Biochar, a porous carbon-based material derived from waste biomass, has been proven effective in removing a wide range of water pollutants (e.g., heavy metals, dyes, persistent organic compounds) due to its favorable physical and chemical properties. Therefore, it has emerged as a promising adsorbent for antibiotics. However, the variability in biochar feedstock (e.g., wood-based biomass, animal manure, aquatic biomass, and municipal solid waste) and the lack of mature modification strategies (e.g., acid/base treatment, oxidation, metal or non-metal doping, and physical methods) pose challenges to its large-scale application. To date, the adsorption efficiency of biochar for antibiotics remains unstable, with removal rates ranging from 40 to 90%. Thus, a timely review of current research progress is crucial. This review summarized the recent advances in biochar modification and its adsorption studies for commonly used antibiotics. The influencing factors, adsorption characteristics and specific adsorption mechanism were comprehensively discussed, and the directions for future research were also proposed.