Photosensitization of TiO 2 by Polyaniline for Salicylic acid Degradation Under Visible Light

The research in this work is part of broadening the photocatalytic performance of titanium dioxide (TiO 2 ) in the visible region by associating TiO 2 with polyaniline to degrade organic pollutants. The polyaniline/TiO 2 composites were synthesized by oxidative polymerization with different percentages of TiO 2 at room temperature and investigated by use of various characterization techniques such as FTIR, XRD and DRS. Infrared spectroscopy in ATR mode revealed the shift of different chemical bands to high wavenumbers, which are attributed to strong polyaniline and TiO 2 interactions. The diffraction pattern of the synthesized composites exhibited crystalline behavior with a crystallite size of about 29 nm. Absorbance measurements have shown an important decrease in gap energy values of the synthesized nanocomposites of approximately 2.5 eV instead of 3.2 eV for TiO 2 alone, revealing that the incorporation of polyaniline has played a crucial role in expanding the light absorption to the visible range for more photocatalytic applications. The photocatalytic activity of the synthesized nanocomposites was tested by degrading salicylic acid in the presence of simulated sunlight. As expected, the photocatalytic activity in the visible region of the synthesized nanocomposites was larger than that of TiO 2 regarding the degradation of salicylic acid. The photocatalytic efficiency increases with the molar ratio TiO 2 /Aniline and with the used amount of photocatalyst. This performance of the photocatalytic activity in the visible range would avoid the use of radiation in the UV range, thus reducing the energy costs of the treatment.