Comparison of Photocatalytic Activities of Two Different Dyes Using Pt-Modified TiO2 Nanoparticles under Visible Light

Abstract

The photocatalytic degradation of Acid Red 91 (AR91) and Acid Yellow 23 (AY23) with different molecular structures and different substitute groups using Pt modified TiO2 (PtTiO2 ) nanoparticles was investigated in the presence of visible light irradiation. Pt-TiO2 nanoparticles were prepared with photodiposition method (PD) and characterized by X-ray diffraction (XRD), scanning electron micrographs (SEM), energy dispersive X-ray micro analysis (EDX), transmission electron microscope (TEM), and UV-vis diffuse reflection spectra (DRS) techniques. The DRS results indicated that the deposition of platinum on TiO2 promoted the optical absorption in the visible region and made it possible to be excited by visible light. Pt-modification of the surface of TiO2 increased photocatalytic activity under visible light irradiation, depending on dye structure (functional group and reactivity of dyes). By comparing the removal efficiency of AR91 and AY23 at the similar conditions, it was observed that the photodegradation rate of AR91 was faster than that of AY23. In conclusion, photocatalytic mineralization of the dyes was monitored by total organic carbon (TOC) decrease. Above 82 and 94% mineralization of AY23 and AR91 was observed using 2 h irradiation.