Solar Driven Dye Removal Composite

Scientists at Swansea University have developed an exciting novel composite material which shows promise as a catalyst for the degradation of environmentally-harmful synthetic dye pollutants, which are released at a rate of nearly 300,000 tonnes a year into the world’s water.

This non-hazardous photocatalytic material effectively removes dye pollutants from water, adsorbing more than 90 % of the dye and enhancing the rate of dye breakdown by almost ten times using visible light.

By heating the reaction mixture at high pressures inside a sealed container, the composite is synthesized by growing ultra-thin “nanowires” of tungsten oxide on the surface of tiny particles of tantalum nitride, resulting in a material with a huge surface area for dye capture.

The material then proceeds to break the dye down into smaller, harmless molecules using the energy provided by sunlight, in a process known as “photocatalytic degradation”. Having removed the harmful dyes, the catalyst may simply be filtered from the cleaned water and reused.

Both of the materials used in the study*, led by Dr. Charles W. Dunnill and Dr. Daniel Jones have attracted significant interest in recent years. However, the true potential of the two materials was only realised once they were combined into a single composite. Due to the exchange of electrons between the two materials, the test dye used within the study was broken down by the composite at around double the rate achieved by tantalum nitride on its own, while tungsten oxide alone was shown to be incapable of dye degradation. In contrast to other leading photocatalytic materials, many of which are toxic to both humans and aquatic life, both parts of the composite are classed as non-hazardous materials.

“Now that we’ve demonstrated the capabilities of our composite, we aim to not just improve on the material further, but to also begin work on scaling up the synthesis for real-world application.” said Dr. Jones. “We’re also exploring its viability in other areas, such as the photocatalysed splitting of water to generate hydrogen.”

*In the Nature open access journal Scientific Reports.