Effect of g-C3N4 loading on TiO2/Bentonite nanocomposites for efficient heterogeneous photocatalytic degradation of industrial dye under visible light

Abstract

TiO2/clay nanocomposites tend to have high photocatalytic efficiency than commercial TiO2 (Degussa P25) due to their high porosity, surface area, the presence of active sites and optical transparency. However, its inactivity in the visible region of the solar spectrum makes it unsuitable for practical use. Hence, the nanocomposite of TiO2 with bentonite clay has been coupled with visible light active graphitic carbon nitride (g-C3N4) by wet impregnation process at room temperature. The as-prepared nanocomposite was then used to photocatalytically degrade (90%) reactive brilliant red dye (RBR- X3BS) in 100 min of time under visible light irradiation. The high activity was attributed due to the suppression of electron-hole recombination as the electron was transferred from g-C3N4 to TiO2 and there was a strong electrostatic interaction between g-C3N4 and bentonite clay. To investigate the reactive species responsible for the photodegradation of dye, different radical scavengers were employed and it was observed that the % degradation was highly affected by the addition of DMSO and ascorbic acid which indicated that electrons (e−) and superoxide radicals (O2-) have played an important role in dye degradation. The reusability efficiency of the as-prepared nanocomposite was examined for 5 consecutive cycles. Complete photo-mineralization of the dye was confirmed by the evolution of CO2 gas (37 ppm) which was monitored by gas chromatography (GC). From the comparative study of literature, it can be proposed that our as-synthesized g-C3N4/TiO2/bentonite nanocomposites could be employed as an efficient photocatalyst for the degradation of RBX-3B dye.