Facile bio-synthesis of cerium oxide nanoparticles, characterization and their photocatalytic potential in the degradation of real tannery wastewater

Abstract The sustainable metal oxide photocatalysts using plant extract presents a viable alternative to conventional chemical synthesis techniques. In this study, spherical shaped cerium oxide nanoparticles were synthesized using ammonium ceric nitrate and Peepal Leaves (PL) extracted and used as a photocatalyst to remove hexavalent chromium and chemical oxygen demand from actual tannery wastewater. The characterization of cerium oxide nanoparticles was carried out using UV-Visible spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, Brunauer-Emmett-Teller surface area analysis, Field Emission-Scanning Electron Microscopy with energy-dispersive X-ray spectroscopy, Raman analysis, High Resolution-Transmission Electron Microscopy and Zeta potential analysis. The band gap energy of 3.25 eV was observed through TAUC plot and the BET surface area, pore volume and pore diameter were measured as 33.545 m²/g, 0.094 cm³/g, and 1.433 nm respectively, indicates the characteristics of mesoporous photocatalyst. 77.2 % of chemical oxygen demand and 84.5 % of chromium (VI) removal was observed at an optimal condition of pH 7, H2O2 concentration 0.0195 mL and cerium oxide dosage of 0.04 g/250ml. The experimental results were well fitted with the pseudo-first order kinetics with the rate constant values of 0.0597 min-1 with the R2 value of 0.9906. Also, the repeatability studies demonstrate that the cerium oxide nanoparticles are found to be unaffected. These studies confirmed that the nanoparticles produced through bio-synthesis method are potential photocatalyst for treating real tannery wastewater. Keywords: Cerium oxide; Bio – synthesis; Photo catalysts; Nanoceria particles; Peepal leaves.