Study on adsorption of tetracycline by red mud-based ceramsite

To understand disposal of antibiotic in wastewater by red mud-based ceramsite (RMBC), a low-cost adsorption material prepared from waste solid red mud, bagasse, powdered glass, and molasses alcohol wastewater, the adsorption of tetracycline from water by RMBC has been studied. Characterization of RMBC was achieved by scanning electron microscope and X-ray diffraction, and the main index parameters of RMBC were tested. Effects of adsorption time, RMBC dosage, initial concentration of tetracycline, temperature, and pH on the adsorption of tetracycline were explored. The adsorption equilibrium isotherms were fitted by Langmuir, Freundlich, and Temkin models. It was found that the Langmuir model described the adsorption process better than the other two isotherm models. Application of Dubinin–Radushkevich adsorption model determined the type of adsorption, which found that the tetracycline adsorption by ceramsite was a physical adsorption. Adsorption kinetics including the pseudo-first order and pseudo-second order kinetic models were investigated and the data fitted better with the pseudo-second order kinetic model than pseudo-first-order kinetic model. The method of regeneration used for RMBC was explored. The results showed that RMBC was an effective and regenerable material used for adsorption treatment of tetracycline.