Visible LED active photocatalyst based on cerium doped titania for Rhodamine B degradation: Radical's contribution, stability and response surface methodology optimization

Abstract

In this study, cerium modified TiO2 catalyst was prepared and the performance on the photocatalytic degradation of Rhodamine B (RhB) in aqueous solution was evaluated. For the band gap engineering, three different percentages of Ce-doped TiO2 (3, 5 and 7 % mol) were synthesized using the simple, efficient, and low-cost sol-gel method. Structural, morphological, and optical analysis, performed by XRD-Rietveld, HRTEM, EDX, XPS and UV–Vis DRS techniques, indicate the formation of nanostructured Ce-doped TiO2 system with anatase phase and band gap in the visible range. Then, Ce-doping percentage, dose of photocatalyst and initial concentration of RhB effects on the removal efficiency were evaluated. The high removal efficiency of 70 % within 150 min was recorded under the condition of: 7 % Ce-doped TiO2 sample, 1.33 g L−1 of dose, and a concentration of RhB of 5 mg L−1. Additionally, a response surface methodology (RSM) was developed for stablish optimal degradation parameters when varying relevant factors for water treatment of real effluents: pH, NaCl, and Cu concentrations. The resulting model shows that the pH is the variable with the highest effect on the photodegradation. Finally, a scavenger study revealed that OH• radicals play a key role in the reaction; and, albeit TOC analysis reveals only 8.55 % of mineralization yield. Cycling study shows that the photocatalyst kept active after 3 cycles of reutilization. The present paper further examinates the parameters affecting Visible LED driven degradation of organic dye in water using Ce-doped TiO2 system and represents an advance in the comprehension of dye degradation with low use of energy.