Ternary system of TiO2 confined chitosan–polyaniline​ heterostructure photocatalyst for the degradation of anionic and cationic dyes

Abstract

Herein, report the preparation of TiO 2 tethered chitosan–polyaniline​ composite (TiO 2 @CS–PANI) by heterogeneous chemical polymerisation​ technique. The crystallographic, morphological and optical properties of the fabricated TiO 2 @CS–PANI composite was described with the aid of powder X-ray diffraction (PXRD), Fourier transform infra red (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), photoluminescence (PL) and thermogravimetry-differential scanning calorimetric (TGA-DSC) analysis. The diffuse reflectance spectra (DRS) evaluation confirmed that the TiO 2 @CS–PANI band gap was reduced compared to that of TiO 2 from 3.2 eV to 2.98 eV. The prepared photocatalyst was utilised for the degradation of toxic Methylene Blue (MB) and Methyl Orange (MO) dye molecules from water in visible light photocatalysis, and is studied in detail. The initial dye concentration of 30 mg/L and photocatalyst dosage of 100 mg were used to investigate the degradation capacity of the composite. The TiO 2 @CS–PANI composite shows extreme degradation efficiency of 92.3% and 89.5% towards MB and MO dyes, respectively. The photocatalyst offers an improved reusability up to five successive cycles. The results established that the TiO 2 @CS–PANI composite could be used as an effective photocatalyst to mineralise toxic dye molecules containing water/wastewater. • A heterogeneous chemical polymerisation method was adopted for the preparation of TiO 2 @CS-PANI photocatalyst. • The band gap of the composite was found to be 2.98 eV. • The composite exhibited high efficiency for the degradation of MB and MO dyes. • The hydroxyl radical was engaged as the primary reactive species. • The stability and reusability performance of the composite was established.