Pyrolysis of marine algae for biochar production for adsorption of Ciprofloxacin from aqueous solutions

[Display omitted] •Pyrolysis of marine algaes with ZnCl2 activator was used to prepared biochar.•ZnCl2-activated method provided mesoporous biochar with enhanced adsorption.•Brown algae-derived biochar showed superior ciprofloxacin removal efficiency.•Valuable aromatics were available in renewable hydrocarbon fuel during pyrolysis. Biochars derived from three species of algae was synthesized by impregnating the green algae Ulva Ohnoi, red algae Agardhiella subulata, and brown algae Sargassum hemiphyllum with ZnCl2 chemical activator and employed as a long-term adsorbent for ciprofloxacin (CIP) removal from water. The results revealed that combination of brown algae and ZnCl2 chemical activator (ZBAB) successfully produced mesoporous biochar with excellent physicochemical characteristics and gave the best CIP adsorption capacity. The ZBAB yielded a high CIP adsorption capacity (190–300 mg g−1) under various parameter effects (initial pH, temperature and major ions). Throughought the surface characterization techniques, the proposed adsorption mechanisms were electrostatic interaction, π-π EDA interaction, pore filling and hydrogen bonding. Moreover, not only algal biochars exhibited innovative and potential adsorbent for rapid and effective remediate pollution from water, but combination of algal biomass and ZnCl2 activator also created renewable source of energy from biomass pyrolysis.