Photocatalytic and photoelectrocatalytic degradation of congo red dye using Cu and S co-doped TiO2/SiO2 nanoparticles under the purple LED light irradiation: optimization of operational conditions

Abstract

The aim of this study was to synthesize Cu and S co-doped TiO2/SiO2 nanoparticles as novel photo-catalysts under the visible light via sol-gel method. The structural properties of the nanoparticles characterized by XRD, DRS-UV/Vis, FE-SEM, TEM and EDX analyses. The results obtained from XRD showed that both the pure and the modified TiO2 nanoparticles comprised only the Anatase phase. The photocatalytic effect of synthesized nanoparticles in the degradation of congo red (as a model of dye polluted wastewaters), was studied. The operational parameters include the irradiation time, pH, the photocatalyst dosage and the pollutant concentration optimized by the response surface methodology (RSM) using the central composite design (CCD). The findings suggested that the optimized conditions for the irradiation time, pH, photocatalyst dosage and the pollutant concentration were 115.98 min, 4.52, 0.08 g and 13.51 ppm, respectively. The photocatalyst degradation under the optimized conditions reached to the 99.8%. Furthermore, the results confirmed that adding thiourea as the sulphur source and copper nitride as the copper source increased the photocatalytic activity in the visible light range. In addition, the UV-Vis spectrophotometry results showed that the synthesized nanoparticles were efficient under the purple irradiation. Finally, coupling the electricity with the photocatalytic process proved that the electrical current was considerably efficient in decreasing the degradation time of removing the congo red dye from aqueous solutions at the high concentrations.

Keywords

• "dye degradation"
• " photocatalyst"
• "congored"
• "codoped tio2"
• "photoelectrocatalyst"