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

•TiO2/PANi compound electrosynthesis can be applied to the remediation of dyes in aqueous effluents.•The adsorption activity of composite material allows combining electrocatalytic and photocatalytic effects.•A three-dimensional matrix of polyaniline (PANi), incorporating TiO2 nanoparticles, can be performed in a single step.•From the decolorization-kinetics fitting session it was found the reaction limiting step to be the dye adsorption on the surface. Electrochemistry was used in the present work as a “clean” technology for the one-step synthesis of titanium-dioxide/Polyaniline (TiO2/PANI) nanocomposite-films (2:1, 4:1 and 6:1 M ratio). Aniline electropolimerization on fluorine-doped tin-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.