A cotton tee-shirt impregnated with titanium dioxide nanoparticles acts as a useful filter for degrading the stubborn dyestuff methyl orange when exposed to direct sunlight. The carbonized fabric of the tee-shirt provides a large surface area architecture on which the photochemical catalytic degradation can take place, according to recent research published in Applied Materials Today [Yang et al., Appl. Mater Today (2016), DOI: 10.1016/j.apmt.2016.03.004].

Organic pollutants from industry, including environmentally persistent dyestuffs such as methyl orange, represent a significant problem for ecosystems across the globe and for human health given their entry into water supplies and the food chain. It is possible to use titanium dioxide as a photocatalyst to break down many such compounds, but finding a technology amenable to a rapid and efficient processing of wastewater, for instance, has proved difficult. Now, an international team from China and the USA have come up with a novel composite that might just fit.

Jun Lou of the Department of Materials Science and NanoEngineering at Rice University, Houston, Texas and colleagues there and at the St John's University, New York and Peking and Shandong Universities, have used a low-cost hydrothermal method to produce titanium dioxide nanoparticles on a carbonized cotton tee-shirt fabric. They then demonstrated that this composite could degrade almost 99% of the methyl orange in aqueous solution on exposure to direct sunlight within about half an hour. The material is still highly functional after ten cycles and still capable of degrading 93% of a methyl orange solution. Previous explorations of titanium dioxide as a photocatalyst have usually relied on high-voltage ultraviolet radiation sources, which are costly and expensive to operate.

The researchers suggest that not only is this inexpensive composite material easy to generate but demonstrates how a unique architecture, woven natural fibers, can represent a novel architecture that has synergistic effects on the photocatalytic reaction due to the carbon doping effect and enhanced charge migration not observed in other types of support for nanoparticulate catalysts. Moreover, the team reports, the nature of the composite facilitates the dispersal and recycling of those particles during the process, which partly underlies its efficacy.

Methyl orange was chosen as a common problematic pollutant, but the same technique should be applicable to other dyes and colored organic pollutants. "The marriage of TiO2 and carbonized cotton T-shirt is promising in practical applications of degrading organic contaminates in water," the team concludes.

"We have plans to explore a scale-up effort to an inexpensive treatment system in the future," Lou told Materials Today.

David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".