Fabrication of Ca-doped TiO2 for enhanced methylene blue degradation under UV-Vis irradiation

Research continues to improve the dye degradation performance of TiO2 nanoparticles (NPs) through doping, tailoring, or modifying the lattice structure. A series of Ca–TiO2 (Ca ions 0.5–2.0 wt%) photocatalysts prepared by wet impregnation method were studied for methylene blue (MB) degradation under UV-Vis irradiation, using different factors, including contact time, pH, initial dye concentration, and dosages. The photocatalyst samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). Characterization results revealed the successful doping of Ca ion on the TiO2 surface, and Ti, O, and Ca were identified by EDX analysis as being present in the Ca-doped TiO2 sample. Calcium improved titania's charge separation capability, favoring the formation of more hydroxyl radicals during irradiation. Another important effect of Ca is the lowered bandgap energy of TiO2, which enhances the light absorption capacity into the visible regions. The photocatalytic performance varied with calcium ions content in the prepared catalysts, and a moderate amount showed the best activity. 1 wt% Ca–TiO2 exhibited a maximum MB degradation of 79.65 % with TOC removal of 52.36 % and followed the pseudo-first-order reactions kinetics with a rate constant of 0.0087 min−1. Notably, both the degradation performance and rate constant of 1 wt% Ca-TiO2 catalysts were much superior to pure TiO2 under the same reaction conditions. This finding suggests that Ca-TiO2 NPs could be a highly effective photocatalyst for the ecologically benign degradation of color compounds in textile wastewater. [Display omitted] •Ca-doped TiO2 photocatalysts were synthesized by wet impregnation method.•Characterization confirmed the incorporation of Ca ions into TiO2 matrix.•Ca ions dopant successfully decreased the bandgap energy.•Maximum 79.65 % MB degradation was obtained for 1.0 wt% Ca ions under UV-Vis irradiation within 3 h.•Ca-doped TiO2 showed much higher dye degradation activity than pure TiO2.