UV-light assisted activation of persulfate by rGO-Cu3BiS3 for the degradation of diclofenac

Abstract

Reduced graphene oxide (rGO)-Cu3BiS3 composites were synthesized via a solvothermal process. The Cu3BiS3 nanoparticles were successfully distributed on rGO at different weight percentages of 5, 10, 15 and 20%, and were characterized for their physicochemical, morphological, structural and optical properties. Fourier transformed infra-red spectroscopy confirmed the incorporation of Cu3BiS3 on rGO, and also confirmed the reduction of GO during the solvothermal process. X-ray diffraction study confirmed the destruction of the layered structure of GO as a result of the compositing process. Photoluminescence studies of the composites, showed that the quenching ability of rGO on Cu3BiS3 was optimal with the composite containing 15% nanoparticles. The photocatalytic activity of the composite was explored in a UV-assisted persulfate (PS) activation process for the degradation of diclofenac, and the effect of process parameters such as pH, catalyst dosage, and PS dosage were explored. The degradation efficiency of the process reached 85% after 60 min using 30 mg of catalyst, PS concentration of 5 mM and solution pH of 7. Radical scavenging experiments showed that the degradation process proceeded significantly through a non-radiative process and the re-usability study confirmed the stability of the composite after three process cycles. The wide applicability of the process was further studied for the degradation of other organic pollutants such as tetracycline, bisphenol, methyl orange and methylene blue. The UV-light assisted rGO-Cu3BiS3 persulfate activation process could therefore be an important, cost effective and highly efficient process for the degradation of a wide range of water contaminants.

Keywords

• Reduced GO
• Copper bismuth sulphide
• Diclofenac
• Dyes
• Photocatalysis
• Persulfate activation