Preparation of AgCl/TNTs nanocomposites for organic dyes and inorganic heavy metal removal
2019
Tsai, Cheng-Yen | Liu, Chen-Wuing | Hsi, Hsing-Cheng | Lin, Kuen-Song | Lin, Yi-Wen | Lai, Li-Chi | Weng, Tsung-Nan
In this study, TiO₂ nanotubes (TNTs) and AgCl-modified TNTs nanocomposites with multiple crystal phases were synthesized through a hydrothermal method without calcination. The resultant samples had a large Brunauer-Emmett-Teller surface area. Additionally, the Ag modification process reduced the recombination rate of electron-hole pairs in the synthesized sample and possessed more oxygen vacancy sites. The surface area of the AgCl-modified TNTs was smaller than that of non-modified TNTs sample; however, the nanocomposites exhibited outstanding photocatalytic performance and adsorption properties. AgCl compounds present on the TNTs surface effectively interacted with Hg⁰, improving the dye photodegradation efficiency. The Hg⁰ removal efficiencies of the TNTs and AgCl-modified TNTs samples were about 63% and 86%, respectively. The crystal violet (CV) and malachite green (MG) removal efficiencies of the AgCl-modified TNTs sample were around 57% and 72%, respectively. Both dyes photodecomposition efficiencies for AgCl-modified TNTs sample are higher than those of TNTs sample. The oxygen vacancy on the AgCl-modified TNTs surface was determined to be advantageous for OH⁻ and arsenate adsorption through ligand exchange. The maximum adsorption quantity of As⁵⁺ calculated by Langmuir equation was 15.38 mg g⁻¹ (TNTs) and 21.10 mg g⁻¹ (AgCl-modified TNTs).
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