Stability and Synergistic Effect of Polyaniline/TiO(2) Photocatalysts in Degradation of Azo Dye in Wastewater

The polyaniline/TiO(2) (PANI/TiO(2)) composite photocatalysts were prepared by the in situ chemical oxidation of aniline (An) in the presence of TiO(2) particles. For this purpose, photocatalysts with different amounts of PANI polymer were prepared and analysed. Fourier-transform infrared (FT-IR) spectroscopy and thermogravimetric (TG) analysis indicated successful synthesis of the PANI polymer and its conductivity was also determined. The micrographs of field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were used to explain the impact of the aniline amount on the aggregation process during the synthesis of the composites. The smallest size of aggregates was obtained for the photocatalysts with 15% of PANI (15PANI/TiO(2)) due to the formation of homogenous PANI. The photocatalytic activity of studied PANI/TiO(2) photocatalysts was validated by monitoring the discoloration and mineralization of Reactive Red azo dye (RR45) in wastewater. The 15PANI/TiO(2) sample presented the highest photocatalytic efficiency under ultraviolet A (UVA) irradiation, in comparison to pure TiO(2). This was explained by the formation of uniformly dispersed PANI on the TiO(2) particles, which was responsible for the synergistic PANI-TiO(2) effect.