Mechanochemical synthesis of La-Sr-Co perovskite composites for catalytic degradation of doxycycline in the dark: Role of oxygen vacancies

Abstract

Direct heterogeneous catalysis is conducted to decontaminate antibiotic polluted water for the first time. Perovskite-structured composites LaxSr(1-x)CoO3-δ (LSC) are synthesized by a green mechanical milling method (as it involves no organic solvent, generates no wastewater, and is viable for industrial-scale use) and applied for the efficient catalytic degradation of doxycycline (DC) via singlet oxygen without the addition of chemical reagents or illumination. The oxygen vacancy produced during ball milling stores numerous electrons. These electrons and singlet oxygen exert a synergistic effect on the catalytic reaction, thereby improving the catalytic degradation of DC. LSC can effectively catalyze the degradation of DC in the dark. The total organic carbon removal efficiency reaches 89.64%, indicating that most DC is eventually mineralized to CO2 and H2O. The catalytic degradation of DC follows two principal degradation pathways involving 13 intermediates. Toxicity prediction indicates that the toxicity of the products initially increases and then decreases with the degradation process and that the final products are not toxic. This study not only allows a facile synthesis route for catalyst preparation but also promotes the development of a green method for wastewater treatment.