Visible light assisted photocatalytic reduction of chromium (VI) using PANI/TiO2nanocomposite from aqueous solutions

Abstract

Polyaniline (PANI)/TiO2 composite was prepared by in-situ chemical polymerisation of aniline monomer in the presence of ammonium persulfate (APS) and Degussa P25. The setbacks of TiO2 semiconductor catalysts like low visible light exploitation and aggregation of TiO2 nanoparticles can be avoided by incorporating PANI. The electron acceptability, electrically tuneable properties, optical and photoelectrical properties, chemical and thermal stability makes the conducting PANI a key for property enhancement of catalysts. The characterisation of nanocomposite was done using Attenuated total reflectance - Fourier transform infrared spectroscopy (ATR-FTIR), Brunauer-Emmett-Teller (BET), Transmission electron spectroscopy (TEM) and Thermal gravimetric (TGA) analysis. This synergic effect of PANI-TiO2 was exploited for the removal of Cr(VI) from the wastewater in this work. PANI is rich in positively charged amino groups that can potentially adsorb Cr(VI) anions and convert to less toxic Cr(III) on the catalyst's surface. Suspended PANI/TiO2 reveals the excellent conversion (99.90%) of Cr(VI) in acidic pH under visible light irradiation. The emeraldine salt form of PANI is more reactive to Cr(VI) and the conversion to emeraldine base form is the endpoint of the reduction reaction. © 2023 Author(s).