Biosynthesis of Selenium (Se) Nanoparticles and their use as Co-Catalyst for Zinc Sulfide (ZnS) Photocatalysed Degradation of Dye

Abstract

The work presented in this thesis outlines the importance of biosynthesized selenium nanoparticles (SeNPs) as co-catalysts for the enhancement of as-synthesized ZnS based photocatalysis. ZnS nanoparticles (ZnSNPs) were synthesized following reflux-condensation approach and examined for its potential to degrade a synthetic dye compound, methyl orange. To enhance the efficacy of ZnS, Se nanoparticles that were synthesized using biogenic approach were calcined with ZnS to generate Se-ZnS nanocomposites (Se-ZnSNCs). The as-synthesized SeNPs, ZnSNPs and the Se-ZnSNCs were characterized by UV-Vis spectroscopy, DLS, XRD and SEM-EDX. Amongst the nanomaterials tested, the Se-ZnSNCs showed higher degradation potential to the extent of 95% when compared to ZnSNPs (55%) and SeNPs (8.5%). Further, the influence of concentration of Se was significant with supplementation of Se by 1wt% which enhanced the photodegrading ability of nanocomposites by 95% when compared to 0.25, 0.5 and 2.0 wt% supplementation of Se during Se-ZnSNCs synthesis. The reaction followed pseudo first-order kinetics with an apparent rate constant k of 8.42 ×10-3 min-1.