Degradation of methyl orange by Au/TiO₂, Ag/TiO₂ photocatalytic nanoparticles prepared using microwave heating

• Tsuji Masaharu

  Research and Education Center of Green Technology, Kyushu University, Kasuga

• Arimura Yuna

  School of Humanity-oriented Science and Technology, Kindai University

• Tanaka Mayu

  School of Humanity-oriented Science and Technology, Kindai University

• Matsuda Kanako

  School of Humanity-oriented Science and Technology, Kindai University

• Kawazumi Hirofumi

  School of Humanity-oriented Science and Technology, Kindai University

• Uto Keiko

  Research and Education Center of Green Technology, Kyushu University, Kasuga

• Hayashi Jun-Ichiro

  Research and Education Center of Green Technology, Kyushu University, Kasuga

• Ago Hiroki

  Global Innovation Center (GIC), Kyushu University

• Tsuji Takeshi

  Interdisciplinary Factory of Science and Engineering, Shimane University

Bibliographic Information

Other Title

• マイクロ波加熱で合成した Au/TiO₂, Ag/TiO₂光触媒ナノ粒子によるメチルオレンジの分解

Abstract

A comparative study was carried out on degradation of methyl orange (MO) by TiO₂, Au/TiO₂, and Ag/TiO₂ photocatalysts in neutral and acidic solutions. Au/TiO₂, and Ag/TiO₂ photocatalysts were prepared by microwave-polyol method in the presence of P25 TiO₂ . The Au/Ti and Ag/Ti atomic ratio in Au/TiO₂ and Ag/TiO₂ catalysts was 1.5%. Initial degradation rates of MO by TiO₂,Au/TiO₂, and Ag/TiO₂ at pH=7 were 0.13, 0.22, and 0.12 min^-1, whereas those at pH=2 were 0.96, 3.1, 2.9 min^-1, respectively.These results indicate that the degradation rates are enhanced for TiO₂, Au/TiO₂, and Ag/TiO₂ by factors of 7.4, 14, and 24 in acidic conditions, respectively. On the basis of effects of additions of isopropyl alcohol, oxalic acid, and p-benzoquinone as scavengers of ･OH, h⁺, and ･O₂^-, major active species for the degradation of MO using TiO₂, Au/TiO₂, and Ag/TiO₂ were determined. Results show that all three active species take part in the degradation of MO in neutral conditions and their contribution was ･OH < h⁺ < ･O₂^- . On the other hand, major active species in acidic solution was ･O₂^-. Combining these results with mass spectroscopic studies on the degradation products led us to conclude that the great enhancement of degradation rates using Au/TiO₂ and Ag/TiO₂ photocatalysts in acidic conditions arises from a great increase in the ･O₂^- concentration due to electron trapping effects of Au and Ag nanoparticles loaded on TiO₂ under UV irradiation. Mass spectroscopic data suggested that major product channels are ring opening and carboxylation in the reactions of ･O₂^- with MO in acidic conditions.

Journal

• Journal of the Japan Society of Electromagnetic Wave Energy Applications

  Journal of the Japan Society of Electromagnetic Wave Energy Applications 3 (0), 14-23, 2019

  Japan Society of Electromagnetic Wave Energy Applications

Details

• CRID: 1390283659828458752
• NII Article ID: 130007762489
• DOI: 10.32304/jemeajournal.3.0_14
• ISSN: 24353450
• Text Lang: ja
• Data Source:
  • JaLC
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed