Removal of cefalexin from aqueous solutions using modified corn stalk-based biochar

With the widespread use of antibiotics, the emergence and spread of drug-resistant bacteria have become a serious challenge in the global public health field. In addition, the incineration of agricultural waste straw can cause air pollution and trigger forest fires. It is urgent to build solutions to address these issues. Three types of biochar were prepared by treating corn stover with phosphoric acid, sodium hydroxide, and zinc chloride, respectively. The adsorption capacity of cefalexin, a first-generation oral antibiotic, was compared across the three types of biochar. The results indicated that biochar activated with zinc chloride exhibits higher mesoporous content and enhanced adsorption activity. Its specific surface area has reached 1494.9 m2/g. This study explored the effects of initial cefalexin concentration and reaction time on adsorption kinetics and equilibrium isotherms. The experimental isotherm data for cefalexin adsorption on biochar were analyzed using Langmuir and Freundlich isotherms. The adsorption isotherm conforms to the Langmuir model, and the maximum adsorption capacity of 230.88 mg/g. The adsorption process was very consistent with the pseudo-second-order dynamic model. This research result indicate that biochar prepared from corn straw cores has a high specific surface area and strong adsorption performance, making it a promising technology for removing antibiotics from aqueous solutions.