Removal of ciprofloxacin lactate by phosphoric acid activated biochar: Urgent consideration of new antibiotics for human health

The long-term accumulation and residue of the emerging pollutant ciprofloxacin lactate (CIP) in the aquatic environment have caused great harm to the ecological environment. In this experiment, CIP was adsorbed on H3PO4-activated cow dung biochar (PBC) prepared with different impregnation ratios. It was found that the secondary pyrolysis of activated original biochar leads to more thorough carbonization, increased aromaticity, hydrophobicity, increased porosity, and increased hydroxyl, carboxyl, carbonyl and a large number of functional groups. When pH value was 5.0, 30P-BC had the highest adsorption capacity. The fitting correlation of PSO models for BC, 10P-BC, 30P-BC, and 50P-BC is higher, with the correlation coefficients of 0.9930, 0.9917, 0.9874, and 0.9886, respectively. The maximum adsorption capacity of materials were 15.27 mg/g (BC), 39.97 mg/g (10P-BC), 53.89 mg/g (30P-BC) and 22.04 mg/g (50P-BC), respectively. The four adsorbents are dominated by single molecule layer chemical adsorption, and there is also a physical adsorption process. The primary mechanism of CIP is the interaction between pore filling and π-π electron donor acceptor, which also includes electrostatic and hydrogen bonding. The removal efficiency applied to actual wastewater and the health assessment of human health risks are worth considering. The removal rate of CIP by 30P-BC in the simulated wastewater experiment reached 97.77 %. Moreover, through the model fitting of the polluted water quality contribution rate to human health exposure, the removal of CIP by 30P-BC can greatly reduce the related risks to human health.