Investigation of Physicochemical Parameters That Influence Photocatalytic Degradation of Methyl Orange over TiO₂ Nanotubes

Abstract

The photocatalytic degradation of a model textile dye, methyl orange (MO), using anodized titanium dioxide (TiO 2 ) nanotubes has been investigated. The effects of light intensity, dye concentration, external bias, pH, and nanotube dimensions (length, diameter, and wall thickness) on MO photodegradation have been examined. The application of a minimal bias of +0.0 versus saturated calomel electrode (SCE) can enhance the dye degradation at least 10 times compared to unbiased conditions for dye concentrations between 20 and 100 µM. The overall initial dye degradation rate demonstrates three types of dependence on dye concentration over a range from 2.5-100 µM. For lower dye concentrations (2.5-40 µM) and natural pH (∼6.0) conditions, Langmuir-Hinshelwood (LH) kinetics was observed. The nanotubes diameter, calcination condition, and the anatase-to-rutile ratio in the crystalline TiO 2 nanotubes together influence the photocatalytic and photoelectrochemical properties of the TiO 2 nanotubes.

One-Dimensional Titanium Dioxide Nanomaterials: Nanotubes

“…This is in line with several other investigations by various researchers 505,[681][682][683][684] . However, there are a number of investigations that either report a maximum in the photocatalytic activity for tube layer thicknesses around 3-7 μm, 151,681,684 or the absence of an influence of the tube length 685 .…”

Photodegradation of bromophenol blue with fluorinated TiO2 composite

“…All of the patterns and planes can be exclusively assigned to anatase, a polymorph of TiO 2 , which is reported to be photocatalytically superior to the other forms of TiO 2 (Smith et al 2009). By applying the Scherrer equation for (101) reflection, the average size of TiO 2 was calculated to be 20 nm.…”

“…Wastewaters containing organic pollutants, such as dyes from textile industries are of concern because of their hazardous effects on the environment (Smith et al 2009). Their presence in water, even at low concentrations has been the driving force for improved water treatment techniques.…”

Anodized titania nanotube array microfluidic device for photocatalytic application: Experiment and simulation

“…The higher dye adsorption on the P25 film compared to the TNA film is possibly due to a larger surface area of the P25 film over the 12 m TNA film. However, it should be noted that the ability of a dye molecule to adsorb onto a titania surface is predisposed to the surface charge of that catalyst (i.e., isoelectric point) and of the dye molecule [38]. In nanomaterials, this can vary depending upon the synthesis method adopted, polymorph, crystallographic planes, as well as crystallite size [12].…”