Electrochemically-assisted fabrication of titanium-dioxide/polyaniline nanocomposite films for the electroremediation of congo red in aqueous effluents

Electrochemistry was used in the present work as a clean technology for the one-step synthesis of titaniumdioxide/Polyaniline (TiO2/PANI) nanocomposite-films (2:1, 4:1 and 6:1 M ratio). Aniline electropolimerization on fluorine-doped fin-oxide electrodes (FTO) was performed by cyclic voltammetry or chronoamperometry within a TiO2 suspension. The fabricated nanocomposites were then tested for the electrocatalytic decomposition of the congo-red-dye chromophore-group in water. Composite 2:1 TiO2/PANI attained an approximate 60 % solution-decolorization after the 90 min processing time (higher than that obtained with the other composites and pure PANI). The nanocomposites did a more efficient dye-removal job by electrocatalysis than by photocatalysis or adsorption. The electrocatalytic kinetics-data were successfully fitted to a pseudo-second-order adsorption-model confirming that, at the applied electric potential, the limiting reaction step is the dye adsorption on the composite film. Infrarred and Raman spectra of the samples detected no significant chemical interaction between TiO2 and the PANI matrix. Thus the main benefit of integrating TiO2 (in low amounts) to the PANI film seems to be an increase in the catalytic surface area.