Enhanced removal of antibiotics by a cerium ion-doped layered double hydroxide photocatalyst

There is an urgent need to develop advanced materials that can effectively remove emerging contaminants such as tetracycline (TC), norfloxacin (NOR), and ciprofloxacin (CIP) antibiotics from water. In this article, a facile and environmentally friendly hydrothermal/co-precipitation approach was used to fabricate Ce-doped layered double hydroxide (MgAl1-xCex-LDH) photocatalysts. The photocatalyst MgAl0.92Ce0.08-LDH possessed highly efficient photocatalytic activity, such as rich mesoporosity, uniform sheet micro-morphology, and the largest specific surface area (131 m2·g-1). These properties promoted the adsorption of antibiotics (TC: 52.89 mg·g⁻¹; NOR: 17.41 mg·g⁻¹; CIP: 11.26 mg·g⁻¹), and the equilibrium data fit well with the Freundlich isothermal and PFO kinetic model. Meanwhile, they enhanced the photocatalytic degradation of antibiotics under visible light. The high photocatalyzed removal efficiencies of TC (90%), NOR (77.23%), and CIP (73.58%) within 90 min surpassed those of many other advanced catalysts. The excellent photocatalytic performance of MgAl0.92Ce0.08-LDH (TC: 0.031 min-1; NOR: 0.018 min-1; and CIP: 0.018 min-1) was attributed to the reduced band gap and efficient migration-separation of photogenerated carriers. The main active substances were confirmed to be photogenerated holes (h+) and superoxide radicals (.O2-) by introducing scavengers (IPA, P-BQ, and EDTA) into the reaction system. After five cycles of experiments, the material still exhibited good stability and outstanding reusability. This study highlights the promising potential of Ce-doped layered double hydroxide in various applications, such as wastewater treatment and environmental remediation, for removal of emerging contaminants.