Adsorption and Photocatalytic Performance of Ternary TiO2/ZnS/GO Composite for the Removal of Dyes

Allysha Riziana, Reduan (2024) Adsorption and Photocatalytic Performance of Ternary TiO2/ZnS/GO Composite for the Removal of Dyes. Masters thesis, Faculty of Resource Science and Technology.

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Abstract

The escalating environmental concerns associated with the widespread use of synthetic dyes in industrial processes necessitate innovative and efficient approaches for their removal from aqueous environments. Ternary composites, with titanium dioxide (TiO₂) as a key component, are recognized for exceptional photocatalytic performance in water treatment. Zinc sulphide (ZnS) and graphene oxide (GO) were added to TiO₂ to enhance its photocatalytic and adsorption properties by promoting charge carrier separation that increases the likelihood of electron transfer reactions, thereby boosting its efficiency in degrading pollutants. This study aimed to assess the efficacy of TiO₂/ZnS/GO composites (1:1:1, 1:2:1, and 2:1:1) in removing single and mixed dye pollutants, including Methylene blue (MB), Methyl orange (MO), and Rhodamine B (Rho B). Various spectroscopic and microscopic techniques comprehensively confirmed the successful creation of TiO₂/ZnS/GO composites. Due to its superior performance, 1.0 g of the TiO₂/ZnS/GO (1:1:1) achieved the highest MB removal rate (98.4%) at an initial concentration of 20 ppm over 150 minutes under UVA irradiation, surpassing other composites. In mixed dyes, the TiO₂/ZnS/GO composite removed 99.1%, 44.3%, and 62.1% of MB, MO, and Rho B, respectively. The presence of different radical scavengers in MB removal showed that the active species in the photocatalytic degradation were •OH and •O2− radicals. TiO₂/ZnS/GO-CaAlg beads achieved 64.2% for MB and 12.2% for Rho B, while MO showed no removal in mixed medium. The recyclability study revealed superior stability of TiO₂/ZnS/GO-CaAlg beads compared to the TiO₂/ZnS/GO powder. These findings provide valuable insights into its efficiency in addressing multiple pollutants.

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