INSTALLING water fountains in hot, arid countries may seem like an extravagant waste of a precious resource. Yet adding a simple chemical to the water can turn the fountain into an efficient water purifier.
Chemists have known for decades that titanium dioxide can catalyse the breakdown of organic molecules in the presence of ultraviolet light. This has been exploited in air-conditioning systems and industrial water cleaners to strip out organic molecules, and to make self-cleaning windows. When spread onto a pane of glass, the chemical chews up grease and helps dirt to slide away. Now a researcher in Britain has built a prototype water-cleaning system that injects the chemical into a fountain. Gianluca Li Puma at the University of Nottingham designed the fountain to produce an umbrella-shaped film of water to maximise the surface area for sunlight to act upon.
Li Puma says the fountain is as cheap and effective as the lumps of carbon currently used to soak up organic pollutants. And because his process degrades the pollutants into harmless compounds rather than simply absorbing them, it leaves no toxic residues. 鈥淚t will look pretty too,鈥� he laughs.
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He envisions installing hundreds of the fountains in ponds or lagoons in sunny countries where they would kill bacteria and strip out pesticide and drug residues. He will present his latest findings at a photocatalysis conference in Toronto, Canada, later this month.