Fluorometric detection of bisphenol A using ß-cyclodextrin-functionalized ZnO QDs.

The estrogenic property of bisphenol A (BPA) leads to potential adverse health and ecological effects. A simple, selective, and cost-effective sensor capable of detecting BPA would have a noteworthy relevance for the environmental system. The present work illustrates the synthesis and characterization of ß-cyclodextrin (ß-CD) functionalized zinc oxide (ZnO) quantum dots (QDs) for the selective detection of BPA. BPA has a fluorescence quenching effect on functionalized ZnO QDs, and the decrease in fluorescence intensity is associated with the BPA concentration between 2 and 10 µM. Under the optimum reaction condition, a good linear correlation was obtained between relative fluorescence-quenching intensity of ß-cyclodextrin-functionalized ZnO QDs and BPA concentration (R2 = 0.9891). The lower detection limit of functionalized QDs for BPA was estimated to be 0.19 µM, which is lower than the toxic limits in aquatic biota. The fluorescence-based detection of BPA may be ascribed to the electron transfer mechanism, which is elucidated with scientific details from the literature.

Photocatalytic degradation of p-nitrophenol using biologically synthesized ZnO nanoparticles.

The present work deals with the photocatalytic degradation of p-nitrophenol as it is a United States Environmental Protection Agency-listed priority pollutant and has adverse environmental and health effects. To eradicate the detrimental environmental impact of p-nitrophenol, the biologically synthesized ZnO nanoparticles were used as a photocatalyst. The degradation of p-nitrophenol was confirmed by decreasing the absorbance value at a characteristic wavelength of 317 nm using the UV-vis spectrophotometer. Reaction parameters such as ZnO photocatalyst concentration of 0.1 g/L at pH 11 in the presence of H2O2 (5 mM) were found to be optimum conditions for p-nitrophenol degradation. The photocatalytic degradation was slowly enhanced in the presence of H2O2 as an electron acceptor. The kinetics of nitrophenol degradation was studied, which follows the pseudo-first-order reaction. The photocatalytic degradation of p-nitrophenol was characterized by using total organic carbon, chemical oxygen demand, and high-performance liquid chromatography analyses. This method is found to be effective as it is environmentally friendly, free of toxic chemicals.