Abstract
HCl-doped polyaniline (PANI) and composites of polyaniline and titanium dioxide (PANI/ TiO2) with different PANI:TiO2 ratios were chemically prepared. The mechanism of preparation of the composite suggested that the aniline was adsorbed on the TiO2 surface before polymerization process took places. PANI and PANI/ TiO2 are characterized using FTIR, SEM, EDX and XRD. The results showed that, the prepared PANI was emelardine salt and has an amorphous structure. The thermal stability of prepared samples was characterized using thermo gravimetric (TG) analysis. PANI is stable up to 200 °C and the relative weights percent of PANI in the PANI/TiO2 composite were 20, 25, 40 and 45 percent for the prepared samples. Photocatalytic activity of PANI/TiO2 composite via Tatrazine (TZ) azo dye was investigated under UV light irradiations and compared with unmodified PANI and TiO2 particles. Results indicated the superiority of the prepared composite photo-catalyst over pure PANI and TiO2. However, the excessive PANI percent tends to form a relatively thick layer and even aggregate on the surface of TiO2. This hinders the migration of excited electrons from the outer PANI layer to the inner TiO2 particles, which consequently leads to decrease the degradation efficiency. A possible mechanism for the photocatalytic oxidative degradation was also mentioned.