Simultaneous electrochemical decolorization of Acid Red 33, Reactive Orange 7, Acid Yellow 3 and Malachite Green dyes by electrophoretically prepared Ti/nanoZnO-MWCNTs anode: Experimental design

[Display omitted] •Facile EPD technique to prepare novel Ti/nanoZnO-MWCNTs electrode.•Efficient improvement in electrochemical properties of Ti/nanoZnO-MWCNTs electrode.•Usage of dyes mixture including AR33, RO7, AY3 and MG as sample pollutant.•Applying electrochemical oxidation process to simultaneous removal of dyes in mixture.•Using combination of multivariate calibration PLS and experimental design CCD methods. Water pollution by pollutants released from various industries is one of the environmental concerns, however, electrochemical oxidation (EO) is a promising option for wastewaters treatment. Anode material is the main parameter in this process, as well as usually, real wastewaters are mixtures of various pollutants. Thus the overall goal of this work is to modification of the titanium substrate by ZnO-MWCNTs nanocomposite through electrophoretic deposition technique for the first time and evaluate its performance in simultaneous decolorization of mixture of dyes including Acid Red 33 (AR33), Reactive Orange 7 (RO7), Acid Yellow 3 (AY3) and Malachite Green (MG). The obtained results of electrode characterizing analyses revealed that the presence of coated ZnO-MWCNTs nanocomposite layer on the titanium surface promoted the electrode properties such as conductivity, stability and electro-catalytic activity which are important in EO processes. To investigate the color removal efficiencies of dyes mixture, the response surface methodology and partial least square as a multivariate calibration method were employed to optimize the EO process and determination of dyes concentration, respectively. Maximum color removal efficiencies were 43.11%, 25.98%, 27.21% and 100% for AR33, RO7, AY3, and MG respectively at optimum conditions. According to the results, the Ti/nanoZnO-MWCNTs electrode has great potential for the decolorization and degradation of various dyes.