At the 247th National Meeting and Exposition of the American Chemical society (ACS), researcher Anne Morrisey from Dublin City University reported her team's new technology, which hopes to provide a simple water purifying system that makes use of sunlight.
Morrisey's team began by using a compound called titanium dioxide (TiO2). TiO2 can act as a catalyst; something that speeds up a reaction without being used up itself, but is usually dependent on UV light. In order for this compound to be useful, it would need to be active in visible light. Therefore, the group started investigating the best shape of TiO2 which would allow this property. Although they found the ideal conformation, it was later discovered that TiO2 was inadequate when used alone. This is where graphene came in. Graphene sheets are made of carbon, and are only one atom thick. The cocktail of these two ingredients together proved effective in the system. The graphene was sticky, catching the pollutants as they flowed through, thus enhancing their proximity to the TiO2 catalyst.
This system was not designed as a first-line water purification system; rather it would serve to remove stubborn harmful molecules from water after it has already been treated by conventional methods. It's hoped that it could help to remove pollution, pesticides and pharmaceuticals to make water safe to drink. Modifying current purification systems to get rid of these residual compounds is not a viable alternative due to the high costs involved. Ideally, the system would be developed to fit into water pipes in areas where large-scale water treatments are not yet feasible. The fact that it is powered by sunlight makes it an ideal and simple candidate solution to a severe problem.
But it isn't quite yet ready to go on the market; the team first need to make sure that the system does not produce harmful by-products when substances are broken down. Tests on the anti-inflammatory drug diclofenac proved successful. This common veterinary drug notoriously caused the death of large numbers of vultures in India and Pakistan.