Improved Adsorption of Tetracycline in Water by a Modified Caulis spatholobi Residue Biochar

/g) together with a developed pore structure. pH displayed a slight influence on tetracycline adsorption, which signified the slight influence of the existence of tetracycline and the charge potential of biochar. Besides, pore filling, hydrogen bonding and π-π EDA stacking interactions possibly resulted in tetracycline adsorption on biochar. Tetracycline adsorption was fast in the original period, followed by a slower rate of adsorption until equilibrium was reached. Adsorption kinetics of tetracycline could be described using secondary and Elovich kinetic models. Adsorption isotherms for tetracycline were well fitted to the Langmuir isotherm model, and the maximum adsorption capacity of KBC was 830.78 mg/g at 318 K. According to a study of the thermodynamics, the adsorption of tetracycline on KBC was an endothermic reaction process. Corresponding results in the present study demonstrated that high-temperature potassium hydroxide activation enabled biochar to effectively eliminate tetracycline from water and wastewater.