Washington, Jan 29 (ANI): A researcher is studying materials
that use light or darkness to purify air filled with toxins
that are harmful to human health and the environment.

The research, conducted by Manindu Weerasinghe from Kansas State
University, Sri Lanka, could one day lead to filters,
humidifiers and other devices that can detoxify air in
windowless rooms, manufacturing facilities and other indoor
areas.

"Indoor pollutants can come from things like asbestos, markers
and new carpet, and are very harmful in just small amounts,"
Newswise quoted Weerasinghe as saying.

"A room like an office or a laboratory that may have few or no
windows will have higher levels of indoor air pollutants than a room that
has lots of windows. Also, if the room does not have good
ventilation those levels would increase," she said.

For her research, Weerasinghe is testing and analysing
photocatalysts and dark catalysts,
materials made by chemically bonding a metal to oxygen.
Photocatalysts react to light while dark catalysts react to
darkness.

The photocatalysts being tested are made from chromium or
vanadium with titanium. Cobalt is used for the dark catalysts.
Finding which metal is most effective at combating pollutants
is key.

Weerasinghe is also adding varying amounts of pure silica to
each catalyst mixture. Silica is the substance used to make
glass and ceramics and serves as an insulator in chemical
reactions. Based on test results, adding silica improves a
catalyst's ability to remove air pollutants.

"Right now it's not really clear why and how pure silica works
so well, so that's something I hope to also answer with more
experiments," she said.

"Glass is not toxic and silica is very abundant and
inexpensive, so it could be a very good material to use if this
work moves from laboratory-scale production to an
industrial-scale production," Weerasinghe said.

Once made, each photocatalyst and dark catalyst is tested in a
chamber filled with air pollutants. Oxygen is added and the
catalyst is exposed to light or darkness, triggering a chemical
reaction that converts air pollutants in the chamber into
smaller, less harmful levels of carbon dioxide over
time.

Although carbon dioxide is not the ideal byproduct, it is
produced at such small levels that it presents fewer problems
to health and the environment than the air pollutants,
Weerasinghe said.

Of the photocatalysts, chromium photocatalysts reduce the most
air pollutants. Although the work is still in its early stages,
Weerasinghe is finding that the results are more complex. Tests
using the cobalt dark catalysts show significant gains over the
photocatalysts.

"In fact, the cobalt system is 10 times more active than the
chromium system at degrading pollutants," Weerasinghe said.

"It's also a rapid response system, meaning that about 10
minutes into the experiment the cobalt starts to react. This is
something that wasn't expected because these experiments are
about using light. But the best results are coming from a
system that doesn't use light to react," she added.

In one instance, Weerasinghe tried to find the point at which
the dark catalyst stopped reacting. After three days into the
experiment no drop-off point could be found. She plans further
studies to investigate this unexpected phenomenon. (ANI)

See more here:
Chemistry research may help free environment of toxins