TiO2 quantum dots: Energy consumption cost,germination, and phytotoxicity studies, recycling photo and solar catalytic processes of reactive yellow 145 dye and natural industrial wastewater

[Display omitted] •Tomato seeds germination process in presence of TiO2QDs samples was evaluated.•Phytotoxicity processes with TiO2QDs samples and P25 TiO2 was studied.•Recycling and Photodegradation processes of Reactive yellow 145 dye were studied.•TiO2QDs prepared from TiCl4 at low calcination temperatures via sol–gel process.•High purity single phase of TiO2QDs prepared samples proved by XRD and HRTEM. The germination of Lycopersicon esculentum tomato seeds that had been planted with water containing TiO2QDs1(2.9 nm), TiO2QDs2 (3.2 nm), and TiO2 (Degussa) without no phytotoxicity effect on the germination process. TiO2QDs1 (2.9 nm) and TiO2QDs2 (3.2) were successfully synthesized at low calcination temperatures: 280 and 310 0C for 180 min, respectively, using the sol–gel process. The synthesized TiO2QDs1(2.9 nm) and TiO2QDs2 (3.2 nm) were characterized by: XRD, FE-SEM, HRTEM, and EDX to analyze the structure, shape, and size of the generated TiO2QDs samples. The photocatalytic activities of the TiO2QDs in the photodegradation of Reactive yellow 145 dye as a commercial dye and actual industrial wastewater samples using both a Xenon lamp light irradiation source and direct sunlight were assessed. They showed highly photocatalytic performances recorded at 85 to 90 percent, and the photodegradation rate was still distinguishable till ten repetition times for the photodegradation process of the reactive yellow 145 dye and till six repetition times for the natural industrial wastewater samples used in this study. Also, an analysis of the photodegradation efficiency of the Reactive yellow 145 dye has been done in terms of the positive effect on the energy consumption ratio (EE/O) as pricing estimations.