Engineering of heterojunction TiO2/CaIn2S4@rGO novel nanocomposite for rapid photodegradation of toxic contaminants

(a) diagrammatic presentation of the photodegradation of MB and CR dyes (blue = MB, red = CR, and (b) electron-hole pairs separation on TiO 2 /CaIn 2 S 4 @rGO. • Novel TiO 2 /CaIn 2 S 4 @rGO composites (rGO-C1 to rGO-C3) were synthesised for rapid degradation of organic dye. • Among them, the rGO-C 2 exhibited significant photocatalytic degradation activity for MB & CR within 15–30 min. • The LC–MS technique has discovered the degradation pathway of both dyes. • It shows excellent degradation activity for real wastewater from the textile industry and landfill leachate. • Moreover, this catalyst may be reused and stable up to four cycles. The in-situ reduction of GO to rGO and simultaneous deposition of TiO 2 and varying concentrations CaIn 2 S 4 10 % (rGO-C1), 20 % (rGO-C2), and 40 % (rGO-C3) resulted in the formation of robust photocatalysts for the degradation of aqueous (azo and thiazine) dyes methylene blue (MB), congo red (CR) and real wastewater. Batch experiments were performed to analyse the effect of pH, catalyst dose, initial dye concentration and time. Compared to other synthesised composites, rGO-C2 demonstrated enhanced photodegradation activity, with a degradation efficiency of almost 100 % within 25–30 min. A possible mechanism for the photodegradation of dyes was also proposed, and post-degradation products were analysed using the LC–MS technique. The kinetic studies show that the degradation efficiency of rGO-C2 followed pseudo-first-order reaction kinetics ( k = 0.027 min −1 . The rGO-C2 photocatalysts demonstrated excellent photocatalytic degradation in real textile industry wastewater and landfill leachate wastewater. It displayed excellent recyclability and stability up to the four-cycle.