Phosphoric acid-activated biochar derived from sunflower seed husk: Selective antibiotic adsorption behavior and mechanism

In recent years, the unnecessary overuse of antibiotics has increased globally, resulting in antibiotic contamination of water, which has become a significant environmental concern. This study aims to examine the adsorption behavior of antibiotics (Tetracycline TC, Ciprofloxacin CIP, Ibuprofen IBP, and Sulfamethoxazole SMX) onto H3PO4-activated sunflower seed husk biochar (PSF). The results demonstrated that H3PO4 could enhance the specific surface area (378.8 m2/g) and create a mesoporous structure of biochar. The adsorption mechanism was investigated using kinetic models, isotherms, and thermodynamics. The maximum adsorption capacities (qmax) of TC, CIP, SMX, and IBP are 429.3, 361.6, 251.3, and 251.1 mg g-1, respectively. The adsorption mechanism of antibiotics on PSF was governed by complex mechanisms, including chemisorption, external diffusion, and intraparticle diffusion. This research provides an environmentally friendly method for utilizing one of the agricultural wastes for the removal of a variety of antibiotics from the aquatic environment.