Degradation of azo dye in aqueous solution using Ti anode coated with MWCNTs–TiO2

Abstract

In this research, the electrophoretic deposition method was used to prepare a titanium electrode coated with multiwall carbon nanotubes–titanium dioxide composite (MWCNTs–TiO2/Ti). The electrode was characterized by transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction and cyclic voltammetry. The photoelectrocatalysis (PEC) activity of MWCNTs–TiO2 composite electrode was investigated through the degradation of Acid Red 33 (AR33) as a model pollutant. A comparison was performed among electrochemical oxidation (EO), direct photolysis (DP), photocatalysis (PC) and PEC processes for decolorization of AR33 solution. Results indicated that color removal (CR) efficiency follows the decreasing order: PEC > PC > DP > EO. In addition, the effect of initial pH of dye solution and current density on decolorization of AR33 was studied. A total 98 % CR and 41.66 % mineralization of AR33 dye were achieved after 60 min of photoelectrocatalytic treatment using the MWCNTs–TiO2/Ti composite electrode operated at a current density of 7.5 mA cm−2 and pH = 5.2.