Photocatalytic degradation of Rhodamine B dye using low-cost pyrofabricated titanium dioxide quantum dots-kaolinite nanocomposite

Abstract

In this study, we report a simple technique for the pyrofabrication of a novel photocatalyst of titanium dioxide quantum dots-kaolinite nanocomposite (TiO2-QDs-Kao) used for rhodamine B (RhB) dye degradation. The photocatalyst was characterized by using different analytical techniques, including XRD, XRF, XPS, FTIR, DTA/TGA, SEM–EDX, TEM, BET, BJH, ZP and UV–Vis DRS. The photocatalytic degradation of RhB was performed in aqueous solutions using the sustainable sunlight energy under atmospheric conditions and fixed neutral medium (pH = 7). The produced photocatalyst exhibited optical band gap energy of 2.85 eV, an improved large specific surface area of 107.724 m2/g with pore radius of 1.45 nm and total pore volume of 0.123 cm3/g. The study indicated a maximum 91% degradation efficiency of RhB after 120 min using the optimum dose 1,400 mg/l of the TiO2-QDs-Kao photocatalyst. The degradation of RhB dye fitted the Langmuir first-order kinetics with rate constant 0.0151 min−1. The radical trapping experiments based on scavengers confirmed that the mechanism of photocatalytic degradation activity was potentially based on electron (e−) and hole (h+) conduction band. The potential energy of the valence and conduction bands EVB and ECB were calculated 2.73 and −0.12 eV, respectively. A triple reusability study confirmed a high stability of TiO2-QDs-Kao photocatalyst with detected degradation efficiencies of 91.0, 89.9, 88.8 and 87.5%, respectively.