Synergistic Effects of UV Radiation and H2O2 on Chloramphenicol Degradation by REE-Based Catalysts

The persistent occurrence of antibiotics like chloramphenicol (CAP) in aquatic systems poses serious environmental and public health risks. This study investigates the photocatalytic degradation of CAP using cerium oxide (CeO2), lanthanum oxide (La2O3), and lanthanum-doped cerium oxide (CexLayO2−δ), synthesized via co-precipitation. The catalysts were tested under a solar simulator, UV-A, and UV-C radiation, both with and without hydrogen peroxide (H2O2). Structural characterization confirmed successful synthesis of nanometric catalysts, with La doping causing lattice expansion in CeO2 and a reduction in crystallite size (from 27 nm in CeO2 to ~20 nm in doped samples). Photolysis alone achieved limited CAP removal (~34–35%), while photocatalysis with La2O3 under UV-A and UV-C improved removal up to 58% and 55%, respectively. Complete degradation was obtained with La2O3 under UV-C in the presence of H2O2 within 15 min. Pareto analysis highlighted the dominant effect of the interaction between radiation and H2O2 (43%), while the catalyst type contributed minimally (0.23%). These findings confirm the potential of REE oxides, especially La2O3, in advanced oxidation processes and underscore the importance of light source and radical generation over catalyst selection alone.