Simplified synthesis of polyaniline–TiO2 composite nanotubes for removal of azo dyes in aqueous solution

Abstract

In this work, polyaniline (PANI) nanotubes (150–200 nm diameter) containing titanium dioxide (TiO2) nanoparticles (about 23 nm diameter) were synthesized through a self-assembly process by the simplified template-free method. It was found that both PANI–TiO2 and PANI nanotubes exhibited significant adsorptivity and photocatalytic activity towards azo dyes; with 1 h adsorption and subsequent 2 h photochemical treatment under Ultra-Violet (UV) illumination, total removal ratios of 98.1 and 98.6 % were achieved for methyl orange and orange II, respectively. The morphology of the product was characterized by scanning electron microscope (SEM). The specific surface area of PANI–TiO2 nanotubes was found to be 16.5 m2/g, compared with 0.27 m2/g for normal polyaniline. Infrared spectrum (IR) and X-ray diffraction (XRD) characterization were employed to analyze the chemical structure of the as-prepared materials. In addition, the one-dimensional material retained a relatively high removal ability after four repeated utilizations. This may provide a new approach for effective separation of organic contamination from aqueous solution by using organic–inorganic semiconductor composites with one-dimensional nanostructure.