Photocatalyst May Clean Phenol And Cellulose From Water
By Sara Jerome
What do you get when you combine water tainted with phenol and cellulose derivates with a new kind of photocatalytic powder? Possibly, clean water, if this concoction just sits out in the sun for a bit.
That's according to researchers at the Institute of Physical Chemistry of the Polish Academy of Sciences, who say they have discovered a new recipe for cleaning up water. The findings would be particularly useful to the paper and wood industries because wastewater from those sectors includes cellulose and phenol derivatives, the academy said in description of the research on Phys.org.
A photocatalyst is "a substance that, after being illuminated by light, can enhance a chemical reaction although the substance itself will not undergo," according to photocatalyst supplier Jita Enterprise. In this particular research, the key part of the new photocatalyst is titanium dioxide mixed with iron or chromium atoms, according to the academy.
"All the materials are commonly available and cheap," the academy said. "The photocatalysts are deposited on appropriate supports – silica grains or zeolites – using common laboratory equipment: a rotary evaporator and an ultrasonic bath."
So, how do photocatalysts clean water? Cheaply and easily, according to the researchers.
"In laboratory conditions the process takes only 15 to 20 minutes and consists of pouring powder with photocatalysts in water. Then, short exposure to solar radiation is sufficient to make water-polluting cellulose or phenol derivatives disappear," the academy said.
"Essential advantages of our photocatalysts include simplicity of production, low manufacturing costs and convenience of performing chemical reactions under natural conditions," said Juan Caros Colmenares, one of the researchers.
The EPA provides human health water quality criteria for phenol. It is 10,000 µg/l for "water + organisms." It is 860,000 µg/l for "water only."
According to the Centers for Disease Control, "ingestion of liquid products containing concentrated phenol can cause serious gastrointestinal damage and even death." It can persist in water for a week before breaking down. Phenol is used to make plastics.
Photocatalysis is used as a cleanup process for other materials, as well.
Photocatalytic reactions are sometimes used to break down "oil grime and hydrocarbons from car exhaust and industrial smog, volatile organic compounds found in various building materials and furniture, organic growth such as fungus and mildew," Jita said.
"The principle of photocatalytic reaction was to accelerate the nature’s cleaning and purifying process using light as energy. Discovered in 1960’s, [a Japanese scientist] found titanium metal, after irradiated by light, could break a water molecule into oxygen and hydrogen gas," the firm said.
Image credit: "morning sun," © 2006 Amehare used under an Attribution-NonCommercial-NoDerivs 2.0 Generic license: http://creativecommons.org/licenses/by-nc-nd/2.0/deed.en