Electrochemical Detection and Photocatalytic Degradation of Brilliant Blue Dye Using Phytosynthesized Cu-Doped ZnO Nanoparticles

Abstract

The escalating industriali zation over the past cenlllry has embellished human life with luxuries but at the same lime it also led to environmental pollution. The untreated discharge of contaminated industrial effluents has badly affected the ecosystem. Among a variety of environmental contaminants. dyes are a major source of pollution that jeopardize aquatic and terrestrial biota. Therefore. researchers are seriollsly engaged in devising effective, affordable and environmentally friendly methods for the detection and elimination of hazardous dyes. The present work reports the synthesis of ZnO and Cu doped nanopartic1es (NPs) via a green synthetic approach lIsing extract of Cassia fistula leaves. The synthesized nanomaterials were characteri zed by voltammetric and spectroscopic techniques. Tauc plot revealed the reduction of the band gap of lnO by copper doping from 3. 1 eV to 2.9 eY. CLI-2nO NPs along with multiwalled carbon nanotubes were used for the fabricati on of the glassy carbon electrode surface to enllance its sensitivity for the detection of brilliant blue dye. Electrochemical impedance spectroscopy revealed the designed sensing scaffold as a pl'Ornising candidate for efficient charge transport of the redox probe between the transducer and the 8nalyte. For the best response of the electrode modifier. a number of experimental conditions were optimized using square wave voltammetry. The designed sensor displayed remarkable sensitivity for the sensing of brilliant blue with a limit of detection value of 0. 1 n1Vf under optimized condition.s. Moreover, the repeatability, specificity and reproducibility of the designed sensor demonstrated irs potential for practical applications. The sensing platform was also used for monitoring the degradation kinetics of the brill iant blue dye. The catalytic degradation of the dye was pe rformed using the synergistic- effect of Cu-ZnO NPs together with Fenton reagent. A 96% degradation of the dye was observed in 60 minutes. Photocatalytic breakdo""ll of brilliant blue was also monitored using UV-visible spectroscopy. The degradation kinetics results of both teclUliques were found in good agreement. Adsorption of brilliant blue was investigated from the decrease in the concentration of dye in solution in the presence of lnO NPs as adsorbent. The adsorption data fitted in pseudo-second order kinetic model by following Langmuir isotherm at lower concentration and Freundlich isotherm at higher concentration.