Improved Photocatalytic Degradation of Rhodamine B dye using Bi0.5Na0.5TiO3 Ferroelectric Nanoparticles: Optimization of pH and poling

Abstract

We report the optimization of the photocatalytic parameters (pH and corona-poling) for Rhodamine B (RhB) dye degradation over Bi0.5Na0.5TiO3 (BNT) nanoparticles under UV-vis light. The BNT nanoparticles were synthesized by the sol-gel method and the XRD analysis confirmed the monoclinic phase structure with Cc space group. No structural distortions were induced by corona-poling, which was confirmed by Raman Spectroscopy. The average size of the nanoparticles was 152 nm with irregular morphology as observed by SEM. The optical bandgap of the sample was 3.23 eV, as derived from the absorbance spectra of the sample. The optimized conditions achieved for photocatalytic degradation were at a catalyst dosage of 50 mg BNT /50 mL of 10 ppm RhB dye solution and pH value 2. The degradation efficiency of the poled BNT sample for RhB dye at pH value 2 was found to be 96.19 % in just 60 minutes. Complete decolorization was attained after 90 minutes of irradiation. In this process, degradation followed the pseudo-first order kinetics, with a kinetic rate constant of approximately 0.08804 min-1, which is around 27 times higher than the rate constant of BNT nanoparticles with dye. A detailed mechanism for the degradation of dye molecules based on pH and poling effect has also been proposed. Based on these results, BNT photocatalyst can be a promising candidate for the treatment of organic dyes.