Synthesis and characterization of chitosan-supported Fe2O3 nanohybrids for rapid sonophotocatalytic degradation of 2,4,6-trichlorophenol

The present study reports the design of heterogeneous photocatalytic system using Fe₂O₃ with chitosan (CS) as a matrix for the sonophotocatalytic degradation of 2,4,6-trichlorophenol (2,4,6-TCP). CS was chosen as a polymer matrix as it is abundant in nature, eco-friendly, and can be easily processed into microparticles, nanofibers, as well as nanoparticles and shows the tendency of adhesion towards a vast range of solid substrates besides serving as a chelating agent toward metallic oxides. The nanohybrids were characterized via Fourier transformation infrared spectrum (FT-IR), X-ray diffraction (XRD), scanning electron microscopy coupled with electron dispersive spectrum (SEM-EDS), thermogravimetric analysis (TGA), and UV-visible diffuse reflectance (UV-Vis-DRS) analyses. Infrared spectroscopy (IR) studies confirmed synergistic interaction between Fe₂O₃ and CS. The XRD measurements confirmed the crystalline morphology while SEM revealed formation of rod-like structures. The TGA studies confirmed higher thermal stability of CS/Fe₂O₃ as compared to pure CS. The optical band gap for CS and CS/Fe₂O₃ was calculated to be 3 eV and 2.25 eV, respectively, from diffuse reflectance spectral (DRS) studies. Rapid photocatalytic degradation of 2,4,6-TCP was observed under UV light irradiation in presence of CS and CS/Fe₂O₃ nanohybrids which revealed 83.19% and 95.20% degradation within a short span of 60 min. The degraded fragments were identified using liquid chromatography-mass spectrometry (LC-MS). The present study on the development of ecofriendly nanohybrid photocatalyst is expected to provide experimental basis for the future development of CS-based photocatalysts which can be easily processed into membranes/filters for the industrial scale degradation of toxic organic pollutants.