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

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 m(2)/g, compared with 0.27 m(2)/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.