Antibiotic removal by activated biochar: performance, isotherm, and kinetic studies

Biomass waste (Chinese traditional medicine residues) is one of the most promising sources of biochar. Here, the present study illustrated the activated biochar (BC_A) was prepared using the herb residue (Astragalus membranaceus) via sodium carbonate (Na₂CO₃) activation for the removal of Cefradine (CF) in wastewater. The adsorbents were characterized by scanning electron microscopy, N₂ adsorption-desorption analysis, Fourier transform infrared spectrum, X-ray diffraction, X-ray photoelectron spectroscopy and zeta potential analysis. The effects of initial pH value, BC_A dosage, initial CF concentration and coexisting ion for CF removal were investigated. BC_A showed much higher absorption capacity for CF (q_m=64.76 mg/g) than the pristine biochar (BC). The uptake capacity of BC_A and BC for CF was found to be pH-dependent. The analysis of the kinetic and isotherm studies indicated that strong chemical-sorption interactions occurred on the surface of BC_A. The removal mechanisms of CF onto BC_A would include π-π EDA interaction, hydrogen bonding, ion exchange and electrostatic adsorption. In addition, the fixed bed experiments demonstrated that BC_A could be a promising and highly effective adsorbent to treat large volume of CF-contaminated wastewater.