Activated carbon—sounds complex, right?
But it’s all around us—for example, as little black specks in those handy filtered water pitchers soon after we insert a new filter.
In fact, many communities use granular and powdered activated carbon in their drinking-water treatment systems.
It’s the key ingredient in many cigarette filters, too—both for factory made cigarettes and in after-market filters for “roll your own” cigarettes.
Activated carbon is also used sometimes as antidote for extreme poisoning.
The removal of water contaminants by activated carbon in drinking- and household tap-water purification is the major market, which constitutes 79 percent of total activated carbon demand in the United States.
That’s the equivalent of about 277 million pounds activated carbon annually. The U.S. activated carbon (for water purification) market had a revenue of $980 million in 2009, with an anticipated compound annual growth rate of 6 percent and a total market revenue of $1.6 billion this year.
Now, Feng “Frank” Xiao, an environmental engineer in the University of North Dakota Department of Civil Engineering, is developing a much more sustainable method to produce this vital material in a world that needs ever increasing amounts of clean water.
“Our team is working on activated carbon sorbents produced from biomass materials—we’re converting what’s usually considered waste into clean activated carbon products for water purification, odor and gas removal,” says Xiao, who is collaborating on this project with Julia Zhao, professor of chemistry at UND.
“Conventionally, there are two ways to make activated carbon—both of which need energy hogging high temperatures (above 700 degrees Celsius or about 1300 degrees Fahrenheit),” says Xiao.
The first is with carbon dioxide or steam, or physical activation.
The second way is by treating the feedstock—the raw material—with chemicals.
“We’re using a novel approach to make activated carbon, the quality of which compares favorably with commercially available activated carbon—the main difference is that our method is greener and more sustainable (from agricultural biomass materials) and takes less energy and less time,” Xiao says. “And we know that our process is scalable.”
Xiao envisions global demand for a cheaper and more sustainable alternative to the current systems of carbon.
“We see practical purposes for this technology: basic use in water treatment; plus it’s effective as a means to purify water by removing pharmaceuticals, pesticides and organic materials,” said Xiao, who holds a Ph.D. degree in Civil Engineering and Environmental Health Sciences from the University of Minnesota and worked three years as a post-doc on agricultural and environmental chemistry at the Connecticut Agricultural Experiment Station.
While store-bought water filters are mostly activated carbon, Xiao notes, similar technology is used on an industrial scale in places such as municipal water treatment facilities.
Most water treatment plants do a great job with current technologies, including commercially available activated carbon. But, Xiao notes, issues remain in the often aged piped distribution systems, so home water filtration—most of which uses activated carbon, too—continues to be important.
“Water is extremely important as fundamental requirement for human life,” Xiao said. “Industrial countries produce many contaminants that can end up in water supplies, so we need better ways to update and operate our drinking water treatment technology to protect public health; ultimate goal is to improve drinking water quality.”
“I estimate that at least one-half of one percent—0.5%—of the activated carbon in the water purification market alone can be upgraded or replaced by our novel activated carbon products, representing an annual gross revenue of $3.5 million. So we’re very excited about this research,” Xiao said.
Funding for this research was provided by Research ND and by the Office of the Vice President for Research and Economic Development. Xiao is the PI and Zhao is the Co-PI.