Construction of CeO2-decorated carboxyl functionalized graphene oxide as a durable and efficient photocatalyst for the ciprofloxacin elimination in wastewater

Background Antibiotic resistances (ARs) in water are a major concern in the aquatic environment, as they are present at very low concentration ranging from ng/L to µg/L. It is necessary to design a photocatalyst with highly efficient ARs degradation utilizing solar energy. Method nanocomposite photocatalyst of CeO2 with carboxylated graphene oxide (cGO) were constructed via carboxylation and hydrothermal processes. The ciprofloxacin (CPX) photodegradation of the CeO2@cGO photocatalysts compared with pure CeO2 was performed under UV and visible light. cGO was employed as support for CeO2 with carboxyl anchoring sites as well as electron sink to prevent rapid charge recombination during photocatalytic reaction. Significant findings FTIR and XRD results show the interaction between cGO's carboxyl groups and CeO2, forming anchoring sites. XPS reveals an increased Ce3+/Ce4+ ratio (0.14) with cGO, creating oxygen vacancies that enhance photocatalytic activity. The CeO2@cGO nanocomposite exhibits a narrower band gap energy (from 3.17 eV to 2.76 eV), improving visible light absorption. In adsorption alone, CeO2@cGO achieves the highest capacity (12.1 mg/g). CPX degradation with 50% CeO2@cGO under UV light reaches 99.23%, compared to 74.67% for pure CeO2. Enhanced charge transfer, electron-hole pair separation, and electrostatic interaction contribute to this improvement. CeO2@cGO demonstrates excellent regeneration capacity and stability, maintaining 93% performance after five cycles. These findings pave the way for advanced photocatalysts for efficient pollutant removal from wastewater.