Cyanide might not seem like the obvious solution to cleaning up water, but as Christina Chang discovered in her junior year at Princeton, the chemical could have significant impact on both pollution cleanup and water purification.

Chang was working in the lab of chemistry professor John Groves, whose team had invented a catalyst that would help produce chlorine dioxide, a powerful disinfectant for water. When Chang added cyanide to the process, the production rate of chlorine dioxide increased 200-fold, a breakthrough. Not only that, the cyanide itself disappeared within seconds, along with the chlorine dioxide. Her question was, why?

“It was a scientific puzzle,” said Chang, who graduated with a bachelor’s degree in chemistry in 2012. Her quest to find the solution was part of a summer-long Lewis research internship funded by the Andlinger Center for Energy and the Environment.

Chang eventually realized that the water disinfectant was disappearing because it was simply doing its job, reacting with cyanide to make cyanate, which is much less toxic than cyanide itself.

With this discovery, Chang and the rest of Groves’ team reasoned that their chemical combination could be added to water coming out of mines, which are contaminated with cyanide. The method could quickly clean up the cyanide. Groves added Chang’s innovation to a pending patent for the catalytic generation of chlorine dioxide.