BiTi-oxides semiconductor: Advanced UV and solar photocatalysts for the aqueous oxidation of organic pollutants rhodamine B and crystal violet

This study aims to develop and evaluate the efficiency of a novel bismuth and titanium-based lamellar double hydroxide photocatalyst (BiTi-HT), prepared by co-precipitation method at constant pH and thermally treated at 400 °C to obtain BiTi-400. The photocatalytic performance of BiTi-400 was assessed under solar and UV irradiation for degrading toxic dyes Rhodamine B (RhB) and Crystal Violet (CV). Photocatalysts characterizations were conducted before and after dyes degradation using XRD, FTIR, TGA/DSC, SEM/EDS, BET, and UV–Vis. It revealed a lamellar structure for BiTi-HT and mixed metal oxide for BiTi-400, with a surface area of approximatively 9 m2/g and a band gap of 2.58 eV, indicating its suitability for visible light photocatalysis. The structure of BiTi-400 remained stable after dye degradation test under solar light, with band gap energies of 2.35 eV for RhB and 2.51 eV for CV. Adsorption in dark reached equilibrium in 5 min, with maximal adsorption capacities of 4.27 and 3.22 mg/g for RhB and CV respectively. Under solar irradiation, BiTi-400 exhibited enhanced degradation capabilities achieving complete degradation of RhB and CV within 60 and 120 min respectively. The degradation kinetics closely adhered to non-linear pseudo-first-order and Langmuir-Hinshelwood models, with a rapid degradation RhB compared to CV. Reusability tests of BiTi-400 photocatalyst confirmed its durable photocatalytic activity and structural stability across 8 cycles. Additionally, the involvement of superoxide radicals (O2•-) are supposed the main pollutants oxidation mechanism. These results demonstrate BiTi-400's potential as an effective photocatalyst for organic pollutants degradation, contributing valuable advancements to environmental remediation technologies. [Display omitted] •BiTi-hydrotalcite exhibit exceptional photocatalytic activity under UV and solar.•Characterization shows unique lamellar structure enhances photocatalytic efficiency.•Significant degradation of Rhodamine B and Crystal Violet dyes in aqueous solutions.•Superoxide radicals play key role in effective oxidation of organic pollutants.•BiTi photocatalysts are reusable and stable, ideal for sustainable water purification.