Engineering Mesoporous Algal-Based Biochars for Efficient Remediation of Norfloxacin Pollution in Marine Environment

Gelidium amansii-derived biochars (GAB) were synthesized through one-step H3PO4 chemical activation at impregnation ratios of 1.5–5 and applied for norfloxacin (NOR) removal in the marine environment. The effects of contact time and initial concentration, especially the salinity and humic acid on NOR adsorption were emphasized. The results showed that the increased H3PO4 impregnation ratio prompted the development of mesoporous and the elimination of oxygen-containing functional groups. Thus, GAB with an appropriate impregnation ratio of 3 (GAB3) exhibited the largest NOR adsorption capability (166.48 mg/g) compare to the others (105.71–159.49 mg/g). NOR adsorption capacity slightly decreased with the increase of salinity, while the adsorption was almost unaffected with the increase of humic acid concentration. The adsorption mechanisms of NOR on GAB in seawater were dominantly through pore-filling, electrostatic attraction, π-π electron donor-acceptor interaction, cation bridging, and negative charge-assisted H-bond. This study provides strategies for efficient remediation of antibiotic-contaminated seawater using algal-based biochars.