A Comparative Kinetic Study on Electro-chemical Decolorization of some Dyes in Mixtures: Multivariate Hard Modelling Technique

In this study, kinetic electro-oxidations of four dyes were simultaneously evaluated on Ti/ ZnOmulti-walled carbon nanotubes anode [1]. The mixture of dyes includes acid red 33 (AR33), reactive orange 7 (RO7), acid yellow 3 (AY3) and malachite green (MG) and the kinetic processes were monitored spectrophotometrically. A time-spectral data was recorded in the time range 0 to 80 min and wavelength range of 220-700nm. The spectra of the analytes were severely overlapped in this wavelength range, a fact which prevents achieving the rate constants of the analytes using common univariate analysis. To overcome this problem, the time-spectral data was resolved by classical least squares method under known pure spectral profiles of the dyes, in turn, the kinetic profiles of the components were analyzed by hard modelling approach [2, 3]. The estimated rate constants of the dyes and their uncertainties were 0.0675((±0.0034), 0.0262 (±0.002), 0.0168 (±8.94×10−4) and 0.0158 (±4.95×10−4) for MG, AR33, AY3 and RO7, respectively. Indeed, the results revealed that MG is strongly degradable and the trend of the rate constants is as follows in descending order: MG AR33 AY3 RO7.