(Ratios: 5, 10, 50, 100, and 200) Polyaniline–TiO2 composites under visible- or UV-light irradiation for decomposition of organic vapors

Polyaniline (PANI)/TiO2 composites with different ratios of TiO2 to PANI were prepared using a hydrothermal–chemisorption process, and their photocatalytic activities for the decomposition of four organic vapors (benzene, toluene, ethyl benzene, and xylene (BTEX)) under both visible- and UV-light irradiation were investigated. Thermal-gravimetric analysis indicated that PANI and TiO2 could be successfully combined to form PANI/TiO2 composites. Both X-ray diffraction and Fourier transform infrared results confirmed that the PANI/TiO2 composites included anatase phase, but not rutile phase TiO2. The UV–visible spectra demonstrated that the light absorption region extended well into the visible-light range for all prepared PANI/TiO2 composites. Under visible-light irradiation, the average photocatalytic decomposition efficiencies of PANI/TiO2 composite increased over a 3-h period from 16 to 61, 28–92, 40–95, and 53–96% for BTEX, respectively, as their ratios of TiO2 to PANI increased from 5 to 200. The average photocatalytic decomposition efficiencies of PANI/TiO2 composite over a 3-h period under visible-light irradiation decreased from 58 to 16, 92–45, 94–62, and 94–69% for BTEX, respectively, as the air flow rate increased from 1 to 4 L min−1. Moreover, the PANI/TiO2 composites showed higher decomposition efficiency than as-prepared TiO2 and P25 TiO2 powders under both UV- and visible-light irradiation, demonstrating improved photocatalytic performance of the PANI/TiO2 composites.