ScienceAsia 30 (2004): 149-156 |doi: 10.2306/scienceasia1513-1874.2004.30.149

Bleaching of Methylene Blue
by Hydrated Titanium Dioxide

Chamnan Randorn,^a Sumpun Wongnawa^b,* and Phadoong Boonsin^b

 ABSTRACT: Hydrated titanium dioxide, h-TiO₂, was prepared by hydrolysis of TiCl₄ with concentrated NH₃ solution. Due to its considerably high surface area h-TiO₂ can adsorb a large amount of methylene blue on its surface, about nine times as much of Degussa P25. It can photocatalyze the decomposition of methylene blue, albeit slightly inferior to Degussa P25 if adsorption is excluded. In the presence of dilute H₂O₂ and with UV light, h-TiO₂ can bleach methylene blue as well as Degussa P25. However, under similar conditions, but without UV light, h-TiO₂ can bleach methylene blue much better than Degussa P25.

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a Department of Chemistry, Faculty of Science, Chiangmai University, Chiangmai, 50200 Thailand.
b Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkla 90112. Thailand.

* Corresponding author, E-mail: wsumpun@ratree.psu.ac.th

Received 27 Oct 2003, Accepted 11 Feb 2004