New Sensor Technology For Making Water Safe

New technology developed by Sandia National Laboratories will allow water utilities to test drinking water for disinfection byproducts cheaply and quickly. The new tool combines a surface acoustic wave sensor (SAW) with a special form of carbon (nanoporous), and it could potentially be used to detect many contaminants in the water and air.

Until recently, water utilities had few options for testing drinking water. The chlorine that is added to water to eliminate dangerous bacteria must itself be kept to a low enough level to avoid contaminating water with dangerous disinfection byproducts such as trihalomethanes. The test of water supplies is often done at labs qualified by the Environmental Protection Agency (EPA), but this process requires several weeks. The only alternatives are expensive: hire a highly-trained chemist to perform the tests to EPA standards or invest in a mass spectrometer system.

Analyzing Water

However, a new and affordable option has emerged: Sandia National Laboratories, working with Parker Hannifin, has developed a table-top tool that quickly and cheaply detects common disinfection byproducts in water. Parker Hannifin has released an online version of the analyzer that can monitor trihalomethane levels every hour.

The device began its life in 2002 as analytical chemist Curtis Mowry’s idea for a sensor to detect industrial waste in water. Collaborating with an engineer from Parker Hannifin in 2006, Mowry finally saw his brainchild appear in 2011 as the Trihalomethane Water Analyzer. Today, Parker Hannifin leads all other companies in the number of trihalomethane analyzers used in North America.

With initial and follow-up work funded by Sandia’s laboratory-directed research and development program, a team of scientists created this device by marrying microsensor technology with cutting-edge research on a special form of carbon called nanoporous carbon. Mowry explained how the sensor works: a surface acoustic wave sensor (SAW) vibrates a wave along a sheet of quartz. Changes in the wave indicate how many chemicals have adhered to the quartz.

Nanoporous Carbon Technology

The downside to such sensors is that quartz is not a sensitive enough substance to collect enough chemicals for accurate readings. Researchers found a way around this problem by coating the quartz with nanoporous carbon. This form of carbon consists of nanofragments of graphene sheets, which trap greater amounts of chemicals. Sandia materials scientist Mike Siegal commented that this carbon coating “turned out to be a thousand times better than any organic coating that Sandia, or anyone else, had ever studied to adsorb volatile chemicals.”

In addition to using this innovative coating on the quartz, the developing team used an older and larger version of SAW technology, which made it easier to apply the carbon coating and produced more sensitive quartz, greatly increasing the efficiency of the device.

On top of testing water to improve public health, the analyzer has other exciting potential uses, including testing for contaminants in the air – even chemical weapons. However, perhaps even more promising are the possible applications of nanoporous carbon technology. Siegel and other Sandia scientists have been exploring how to apply this carbon to battery anodes to produce higher density batteries. These batteries could extend the life of cellphones, power electric cars more efficiently, and have many future technological ramifications.