Photocatalytic Activity of Titanium Dioxide Nanotubes Following Long-Term Aging.

Stephen Abela,Paul Refalo,Maurice Grech,Alex Rizzo,Clayton Farrugia,Edwin Zammit,Ryan Xuereb,Frederick Lia

doi:10.3390/nano11112823

Abstract

Anodic titanium dioxide (TiO2) nanotubes were found to be active photocatalysts. These photocatalysts possess a high surface area, even when supported, rendering them potential candidates for water treatment. In this work, photocatalytic surfaces were produced by anodizing commercially pure Ti plates using two different electrolyte compositions and correspondingly diverse process parameters. Changes in the physical and chemical stability as well as photocatalytic activity were studied over a fifty-two-week aging process. During this period, the nanotubular surfaces were exposed to flowing synthetic greywater, solar irradiation, and the natural environment. The physical and phase stability of the materials anodized using the organic electrolyte were found to be outstanding and no degradation or change in crystalline structure was observed. On the other hand, materials anodized in the aqueous electrolyte proved to suffer from light-induced phase transition from anatase to rutile. Surfaces synthesized in the organic electrolyte were more resistant to fouling and showed a better tendency to recover photocatalytic activity upon cleaning. In conclusion, the nanotubes produced in the organic electrolyte proved to be stable, rendering them potentially suitable for real-life applications.

Highlights

Water scarcity affects at least 11% of the European population and 17% of EU territory.This has cost an estimated €100 billion over the past 30 years [1]
The results obtained from tests conducted on the aged samples are described and discussed
Freestanding nanotubes were formed in all cases except in the case of the

Summary

Introduction

Water scarcity affects at least 11% of the European population and 17% of EU territory.This has cost an estimated €100 billion over the past 30 years [1]. Water Scarcity and Drought and identified seven policy options for tackling the issue of water scarcity Some of these policies involve the following: the removal or restriction of subsidies on water tariffs, ensuring a more efficient water use, consideration of additional water supply infrastructures, and the development of water efficient technologies and practices. To date, in Europe an estimated 30% of town water supply is used for toilet flushing [2]. Treatment of greywater could be carried out in situ using photocatalytic degradation of the pollutants in the effluent from the same residence. This technology allows for the effective treatment of greywater without the addition of chemicals. Such technology has already been shown to be effective [3,4]

Methods

Results

Conclusion