Selective adsorption and photocatalytic degradation of chlortetracycline hydrochloride using a La2Ti2O7/acid-modified coal-bearing strata kaolinite composite

Abstract

A La2Ti2O7/acid-modified coal-bearing strata kaolinite (La2Ti2O7/AK) composite was successfully prepared using a simple hydrothermal method. The composite prepared was used in the selective adsorption and photocatalytic degradation system of chlortetracycline hydrochloride (CTC·HCl). This system demonstrated the successful preparation of La2Ti2O7/AK, a large amount of active space, and excellent photoelectric properties, which contributed to the adsorption and photocatalytic degradation of CTC·HCl by La2Ti2O7/AK. The results demonstrates that the prepared composite has excellent selective adsorption performance for CTC·HCl in a single solution at pH = 4 but poor selective adsorption performance for CTC·HCl in binary solutions (CTC·HCl/TCH and CTC·HCl/OTC). Furthermore, the effects of the solution pH, material types, and inorganic ions on CTC·HCl adsorption are attributed to the synergistic effect of various adsorption mechanisms. Moreover, the free radical capture and electron paramagnetic resonance (EPR) experiments confirmed that the main free radicals for photocatalytic degradation are ·O2−, OH, and h+. Finally, the adsorption and photocatalytic degradation efficiency of La2Ti2O7/AK in case of CTC·HCl in wastewater remained at > 70 %. Therefore, its excellent adsorption, unique selectivity, excellent photocatalytic degradation, wide applicability, and outstanding stability in wastewater make it an ideal catalyst for the selective adsorption and photocatalytic degradation of CTC·HCl from complex wastewater.