Electrochemical detection and removal of brilliant blue dye via photocatalytic degradation and adsorption using phyto-synthesized nanoparticles

Herein, we report a sensitive electrochemical platform prepared by modifying the electrode surface with copper-doped zinc oxide nanoparticles; these nanoparticles were prepared via a green synthetic approach using the extract of Cassia fistula leaves and multiwalled carbon nanotubes (MWCNTs). For the best response of the electrode modifier, a number of experimental conditions were optimized to obtain the most intense signal of the target analyte Coomassie brilliant blue using a rapid analysis technique square wave voltammetry. The designed sensor displayed remarkable sensitivity for Coomassie brilliant blue with a detection limit of 0.1 nM under the optimized conditions. Moreover, the repeatability, specificity and reproducibility of the designed sensor demonstrated its potential for practical applications. The sensing platform was also used for monitoring the degradation kinetics of the Coomassie brilliant blue dye. Catalytic degradation of the dye was performed using the synergistic effect of Cu-ZnO NPs together with Fenton reagent. The dye degraded by 96% in 60 minutes under neutral conditions, which is one of the main achievements of this work that has never been reported. The photocatalytic breakdown of Coomassie brilliant blue was also monitored using UV-visible spectroscopy. The degradation kinetics results of both techniques agreed well. The adsorption of Coomassie brilliant blue using ZnO NPs was monitored spectrophotometrically. The adsorption data were fitted in a pseudo-second order kinetic model by following the Langmuir isotherm at lower concentration and Freundlich isotherm at higher concentration.