Optical and dielectric properties for the determination of gap states of the polymer semiconductor: Application to photodegradation of organic pollutants

The conductor polymer emeraldine polyaniline (PANI) prepared by chemical route at −7 °C, is thermally stable up to 300 °C. The optical and electrical properties were studied by the diffuse reflectance spectra R(λ) in the range (300-2500 nm) to calculate the refractive index n (λ), optical conductivity (σopt), extinction coefficient (k), dissipation factor (tan δ) and relaxation time (τ). The forbidden band (Eg = 1.8 eV), was evaluated and confirmed by different methods. As application, the results show that the adsorption kinetic follows a pseudo first order for Orange II and the second order for Quinoline Yellow. The PANI thus prepared and studied has been used in the field of the environment. A systematic study of adsorption and photodegradation of Orange II and Quinoline yellow was carried out giving a depollution rate >90% in a time of 90 min.