Adsorption and photocatalytic degradation of methylene blue by titanium dioxide nanotubes at different pH conditions

Pham Van Viet and Hai Nguyen Tran

Abstract

Titanium dioxide nanotubes (TNTs) are synthesised by hydrothermal method. Characterisations of TNTs are surveyed by transmission electron microscopy (TEM) images, x-ray photoelectron spectroscopy (XPS), and the Brunauer–Emmett–Teller (BET). The adsorption capacity and photocatalytic degradation of TNTs toward methyl blue (MB) are investigated under different pH values from 1 to 12. The results demonstrated that medium pH affected the charged state of hydrothermally synthesised TNTs surface, the adsorption capacity and photodegradation activity of TNTs. The study indicated that the adsorption capacity of hydrothermally synthesised TNTs is strongest at pH 6 and weakest at pH 1. In addition, the MB photocatalytic degradation of TNTs exhibited the highest efficiency of 86.87% at pH 5 and the lowest one of 42.24% at pH 1 after 300 min under UV irradiation.