Materials Science Forum Vol. 1197

Abstract: This work explores an alternative approach to address the pollution issue of dye residues in water bodies. This study intends to improve sunset yellow (SY) dye degradation efficiency by using microcrystalline cellulose supported-nanoTiO₂ composite photocatalysts assisted by UVC illumination. The photocatalysts were constructed using a facile chemical mixing procedure with various ratios of MCC to TiO₂ (0.3:1, 0.5:1, and 0.7:1). The characterization was carried out using FTIR to establish their functional groups. The synthesis procedure was constructed to enhance charge carriers’ separation and expand light absorption for high photoactivity. Under natural conditions, SY photodegradation was at its peak with almost complete degradation by using 0.5:1 ratio, with major active species were found to be h_vb⁺ and •OH radicals. The rate constant reached 2.33 × 10^-2 min^-1 corresponding to pseudo first-order model, exceeding the performance of pure TiO₂.

Abstract: This research studied the synthesis of nanozero-valent iron supported on granular activated carbon (nZVI/GAC) catalyst for degradation of paraquat. The catalyst was synthesized with the ratio between the weight of ferrous sulfate heptahydrate and granular activated carbon (2:1). The prepared catalyst reacted with sodium borohydride to synthesize nanozero-valent iron. The characteristics of the chemical functional groups on the surface of the catalyst were studied by FTIR, and a peak corresponding to Fe–O was observed at 624 cm⁻¹. The iron loading of the nanozero-valent iron supported on granular activated carbon (nZVI/GAC) by using XRF was determined to be 19.21 %wt. The morphology of the catalyst was analyzed by SEM, which confirmed the presence of nanozero-valent iron on the surface of the granular activated carbon. The factors influencing the degradation of paraquat were investigated, including the initial pH, the dosage of H₂O₂, and the initial concentration of paraquat. It was found that the optimum conditions for paraquat degradation were obtained when 1 g of nZVI/GAC was used at an initial pH of 4 with 5 mmol of H₂O₂ for an initial paraquat concentration of 30 mg/L. Under these conditions, the degradation efficiency reached 78% within 1 hour.

Abstract: The GO/TiO₂ composites containing 3–11 wt% GO were successfully synthesised via a simple mixing method to investigate their optical properties. SEM analysis revealed spherical TiO₂ nanoparticles with an average size of ~28 nm and a uniform dispersion of GO within the composite structure. UV–Vis diffuse reflectance spectroscopy results indicated that GO incorporation shifted the absorption edge toward the visible-light region. The optical band gap decreased from 3.37 eV for pristine TiO₂ to 2.79 eV for the GO/TiO₂ composite containing 11 wt% GO. These findings demonstrate that GO effectively modifies the electronic structure of TiO₂, enhances visible-light absorption, and improves its potential for solar energy applications.