Enhanced photocatalytic degradation of Reactive Green 19 dye using earthworms like T-ZnO-CuO nano-composite material as a S-scheme heterojunction photocatalyst

Abstract

Due to increasing organic dye pollution in the water environment, green and efficient photocatalyst are urgently needed to solve this problem. This study hypothesizes that green-synthesized nanocomposites, using plant leaf extracts, will significantly enhance the efficiency of organic dye degradation without the environmental drawbacks associated with traditional methods. Herein, enhanced degradation of Reactive Green 19 (RG 19) dye using earthworm like T-ZnO-CuO (TZC) nano-composite was reported. T-ZnO (TZ) and TZC nano-composite were synthesized using leaves extract of Thevetia peruviana plant. In the synthesis process, Thevetia peruviana leaves extract acts as a capping, stabilising and reducing agent, and additionally create a unique surface morphology of TZC nano-composite. The establishment of TZ and TZC nano-composite samples were investigated using FT-IR, XRD, FE-SEM with EDX, HR-TEM and UV–VIS DRS spectroscopy. Furthermore, band gap energy of TZ and TZC nano-composites were calculated using Tauc’s plot. The band gap energy of TZC2 nano-composite was determined to be 2.80 eV. The nano-composite photocatalyst (TZC) was utilised in the degradation of RG 19 dye with 96.89 % efficiency in 150 min at 20 mg/L dye concentration, pH=7.5, and 0.6 g/L catalyst dose. In order to investigate the tentative photocatalytic mechanism, scavenging study, recyclability experiment, and stability were also investigated. The findings show that O2− and OH radical species have higher degree of involvement in the degradation process. The kinetics of the degradation of RG 19 dye follows pseudo-first-order kinetics.