Cadmium selenide quantum dot-zinc oxide composite: Synthesis, characterization, dye removal ability with UV irradiation, and antibacterial activity as a safe and high-performance photocatalyst.

In this paper, cadmium selenide quantum dot (CdSe QD)-zinc oxide (ZnO) nanocomposite (CdSe QD-ZnO) was synthesized and characterized and its photocatalytic dye degradation ability was investigated. The XRD, FTIR, UV-Vis, AFM and SEM were used to characterize the synthesized nanomaterials. The correlation coefficient of pseudo-first-order kinetic reaction is 0.98. The rate constants from 20 to 30 mg/L of pollutant concentrations was reduced by the order of 0.9. The temporal change in dye concentration reduces as the photocatalyst dosage increase up to optimum value of 0.04 g/L, then beyond that value the increase in the dosage becomes detrimental. Antibacterial activity of the synthesized nanocomposite as a safe photocatalyst was studied in details. Antibacterial activity of as prepared samples was also examined against Escherichia coli (E. coli). For in vitro study, Human umbilical vein endothelial cells (HUVEC) was utilized for the modeling of toxicity of each as prepared samples as representative of human normal cell line. In vivo study was conducted using leeches (Hirudo orientalis). In the presence of ethanol as hydroxyl radical (OH) scavenger, the removal efficiency significantly depresses compared to the di methyl sulfoxide as electron scavengers suggesting OH possesses a major role in photocatalytic dye (Basic Red 18: BR18) decolorization. By coupling with CdSe QD, the zone of inhibition was greatly increased suggesting the size dependent inactivation of E. coli. The results presented that the composite had no significant effect on the proliferation of HUVEC normal cells. In addition, the treatment of cells with ZnO and the composite does not impact on the cell morphology.