University of Bath

Metal Oxides for Tandem Photocatalysis Water Treatment

This project aims to produce semi-conductors via the electrochemical process, anodization, to act as a photocatalyst for use in water treatment.

The aim of this research is to develop a nanostructured wire catalyst to degrade pollutants via a flow through reactor. In order to achieve this aim, the following objectives were identified:

  • Design and commission an anodization rig, suitable for producing oxide nanostructures on a metal wire (zinc or titanium)
  • Optimise the anodization process for Zn and Ti wire
  • Identify the effect of anodization time and surface morphology, and whether this translates to different photocatalytic behaviour
  • Determine key experimental parameters, such as flow rate, addition of electricity, atmospheric conditions, pH

Project outline

The project aims to produce semi-conductors via the electrochemical process, anodization, to act as a photocatalyst for use in water treatment. Upon absorption of UV light, a semiconductor will produce reactive hydroxyl radicals which can react with persistent contaminants to degrade them into products that are more readily biodegradable. The process of anodization was optimised for producing zinc oxide and titanium dioxide, and key experimental parameters were highlighted such as flow rate and atmospheric conditions. The addition of electricity to the photocatalysis was also investigated to determine if this could improve pollutant degradation. The photocatalytic efficiency of the system was monitored using the model pollutant, phenol. Other pollutants monitored included carbamazepine, which is a very persistent, photo-resistant pharmaceutical.

Science

This research has produced a novel tubular photocatalytic reactor, which allows for increased efficiency as well as optimised ZnO anodization conditions and a novel sustainable TiO2 anodization process, which removes the use of hazardous fluoride based electrolytes. This research has been presented at the 15th IWA Leading Edge Conference on Water and Wastewater Technologies in Nanjing, China. Two manuscripts are currently under preparation.

Impact

The aim of this research is to increase the sustainability of photocatalysis, this was done by optimising anodization conditions, such as finding alternatives to hazardous fluoride electrolytes, but also the project produces immobilized photocatalysts with a simple synthesis, which does not require an expensive, multiple step process. It also highlights the efficiency of using a tubular photocatalytic reactor.

This is the PhD project of Caitlin Taylor from the Department of Chemical Engineering. Email address: C.Taylor2@bath.ac.uk