It has long been known that ultraviolet light can naturally clean contaminated water, preventing a host of bacterial and viral diseases. The technique, often referred to as SODIS, or Solar Water Disinfection, works with ultraviolet rays alone -- especially if those UV rays are generated in sufficient concentrations.
The issue of clean water has been approached by a number of innovative scientists with ideas ranging from using common chemicals to clean water to developing technological solutions such as hand-cranked pre-filter and UV treatment bottles that could be distributed widely in problem areas.
Young scientist Deepika Kurup's idea appears to offer a novel twist on the technology: she investigated the ability of photocatalysts to accelerate the UV-decontamination power of simple sunlight. She tested two photocatalysts, titanium dioxide (TiO2) and zinc oxide (ZnO), coated on rods that fit in the middle of the ubiquitous two quart (two-liter) plastic water bottles.
Deepika designed a simple but elegant experiment. She created three UV-treatment vessels with catalytic rods: two using each photocatalyst on its own and a third with a combined TiO2-ZnO coating. A fourth plastic bottle without any photocatalyst served as a control. Deepika then sampled water from the bottles every three hours, using an incubator she developed herself to grow colonies in order to test the water contamination levels.
Deepika was able to prove that the combined TiO2-ZnO rods significantly accelerated the treatment time necessary to achieve clean water using the sun for treatment.
The materials Deepika chose for her project are cheap and relatively available, offering a good fit for meeting the widespread demand for cleaner water. Additionally, the photocatalysts can be re-used repeatedly, unlike chemicals treatments (e.g. chlorine or iodine).
Moreover, Deepika's enthusiastic presentation demonstrates her excellent communication skills, a talent that will serve her well as she pursues her scientific interests. Unfortunately, the videos at the Discovery Education 3M Young Scientist Challenge website are not enabled for embedding, but it is worth linking over there for a look.