[Adsorption Characteristics of Tetracycline by CuFeO₂-modified Biochar]

CuFeO₂-modified biochars were prepared through co-precipitation and hydrothermal methods, and the composites had high efficiency removal for tetracycline (TC) from water. The CuFeO₂-modified biochar with a 2:1 mass ratio of CuFeO₂ to BC450 (CuFeO₂/BC450=2:1) demonstrated the best adsorption performance. The kinetic process of TC adsorption by CuFeO₂/BC450=2:1 was well fitted with the intraparticle diffusion model, suggesting that the adsorption process was controlled by film and pore diffusion. Under the condition of neutral pH and 298 K, the maximum adsorption capacity of the Langmuir model of CuFeO₂/BC450=2:1 was 82.8 mg·g^-1, which was much greater than that of BC450 (13.7 mg·g^-1) and CuFeO₂(14.8 mg·g^-1). The thermodynamic data suggested that TC sorption onto CuFeO₂/BC450=2:1 was a spontaneous and endothermic process. The removal of TC by CuFeO₂/BC450=2:1 increased first and then decreased with increasing pH, and the maximum adsorption occurred under the neutral condition. The strong adsorption of TC by CuFeO₂/BC450=2:1 could be attributed to better porosity, larger specific surface area, and more active sites (e.g., functional groups and charged surfaces). This work provided an efficient magnetic adsorbent for removing antibiotics.