Abstract
Pure TiO 2 and erbium ion-doped TiO 2 (Er 3+-TiO 2) catalysts prepared by the sol–gel method were characterized by means of XRD and diffusive reflectance spectra (DRS). The XRD results showed that erbium ion doping could enhance the thermal stability of TiO 2 and inhibit the increase of the crystallite size, and the DRS results showed that the optical absorption edge slightly shifted to red direction owing to erbium ion doping and the Er 3+-TiO 2 catalysts had three typical absorption peaks located at 490, 523 and 654 nm owing to the transition of 4f electron from 4I 15/2 to 4F 7/2, 2H 11/2 and 4F 9/2. With a purpose of azo dyes degradation, orange I was used as a model chemical. And the adsorption isotherm, degradation and mineralization of orange I were investigated in aqueous suspension of pure TiO 2 or Er 3+-TiO 2 catalysts. The results showed that Er 3+-TiO 2 catalysts had higher adsorption equilibrium constants and better adsorption capacity than pure TiO 2. The adsorption equilibrium constants ( K a) of Er 3+-TiO 2 catalysts were about twice of that of pure TiO 2. The maximum adsorption capacity ( Q max) of 2.0% Er 3+-TiO 2 catalyst was 13.08 × 10 −5 mol/g, which was much higher than that of pure TiO 2 with 9.03 × 10 −5 mol/g. Among Er 3+-TiO 2 catalysts, 2.0% Er 3+-TiO 2 catalyst achieved the highest Q max and K a values. The kinetics of the orange I degradation using different Er 3+-TiO 2 catalysts were also studied. The results demonstrated that the degradation and mineralization of orange I under both UV radiation and visible light were more efficient with Er 3+-TiO 2 catalyst than with pure TiO 2, and an optimal dosage of erbium ion at 1.5% achieved the highest degradation rate. The higher photoactivity under visible light might be attributable to the transitions of 4f electrons of Er 3+ and red shifts of the optical absorption edge of TiO 2 by erbium ion doping.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.