Synthesis and characterization of Nd-TiO2 and Nd-ZnO nanostructures for photocatalytic degradation of textile wastewater

This study was executed on textile wastewater degradation using laboratory-prepared Nd-TiO2 and Nd-ZnO nanostructures by sol-gel and hydrothermal ultrasonication methods, respectively. The synthesized nano-photocatalysts were fully characterized using XRD, FE-SEM/EDX, FT-IR, and UV-DRS. The XRD analysis shows that TiO2 crystalline size with Nd doping is 6.14 nm with only the anatase phase, whereas ZnO is 29.59 nm. DRS spectra show that the energy band gap of the doped TiO2 nanostructure was 3.16 eV, whereas, in the case of the Nd-ZnO nanostructure, it was 3.19 eV, which further indicates more photocatalytic activity. Photocatalytic application for textile wastewater degradation was tested regarding biological oxygen demand and chemical oxygen demand. The maximum degradation of textile wastewater at dilution 1:9 was observed to be 96% and 91% for Nd-TiO2 and 89% and 87% for Nd-ZnO under UV and solar irradiations, respectively, with the optimized catalyst dose of 0.2 g/L (Nd-TiO2) and 0.3 g/L (Nd-ZnO) at a pH of 7.52. The recyclability shows a slight decrease in efficiency throughout five cycles. The photocatalytic activity of Nd-TiO2 was higher due to the favorable band gap and smaller crystallite size. The findings indicate that solar light may be a long-term, cost-effective renewable source for large-scale wastewater treatment.