Distinguishable Recycling and Photodegradation Processes of Real Industrial Effluents and Blue Dianix Dye in the Presence of Different TQDs Size

Three titanium dioxide quantum dots (TQDs) samples were successfully synthesized at low calcination temperatures via a modified precipitation method at T1 = 330, T2 = 360, and T3 = 400 °C. The synthesized TQDs samples were characterized by: XRD, FE-SEM, HRTEM, and EDX to analyze the crystallinity, purity, and existence of asymmetric circle forms for the TQDs catalysts. Also, the surface area, band gap energy, and crystallite size at different calcination temperatures are 322.32 m 2 /g, 3.20 eV, and 4.9 nm at 300 °C, 292.39 m 2 /g, 3.14 eV, and 5.4 nm at 360 °C, and 254.66 m 2 /g, 3.07 eV, and 6.2 nm at 400 °C, respectively. A xenon photoreactor (70 W/cm 2 ) was used to evaluate the photodegradation process of Blue Dianix dye and sunlight for real industrial effluent treatment. The photocatalytic activity decreases as the crystallite size increases in the TQD samples. Photocatalytic activity of TQDs due to their distinguishable crystalline domain size of less than 10 nm and their high surface area. The photodegradation rate of real industrial effluents was evaluated according to the COD limits permitted by Egyptian environmental law. Also, TOC and COD analyses evaluated 12 recycled samples of TQDs.