Spectrophotometric and kinetic studies on electro-chemical decolorization of dyes in mixtures: combination of classical least squares and hard modelling approaches

In this study, kinetic electro-oxidations of four dyes were simultaneously evaluated on Ti/ ZnO-multi-walled carbon nanotubes anode. The mixture of dyes includes acid red ۳۳ (AR۳۳), reactive orange ۷ (RO۷), acid yellow ۳ (AY۳) and malachite green. The kinetic processes were monitored spectrophotometrically. A time-spectral data was analyzed in the time range ۰ to ۸۰ min and wavelength range of ۲۲۰-۷۰۰ nm which suffer signal overlapping of components problem. To obtain the kinetic degradation profiles of the components, the whole data was resolved by classical least squares method as a reliable method for analysis of the data in which there are no selective responses for the analytes.  Then, the kinetic rate constant of each dye decolorization together with its uncertainties were estimated by applying hard modelling approach. The obtained rate constants were ۰.۰۶۷۵ s-۱, ۰.۰۲۶۲ s-۱, ۰.۰۱۶۸ s-۱ and ۰.۰۱۵۸ s-۱ for MG, AR۳۳, AY۳ and RO, respectively, revealing that MG is the most degradable dye.

Keywords:

Signal overlapping , Multivariate analysis , Electro-oxidation process , Azo dyes , Kinetic processes