June 2009, Vol. 21, No.6

Research Notes

Buckyballs Aid in Preventing Biofouling

Duke University (Durham, N.C.) engineers have found that spherical carbon molecules known as “buckyballs” hinder the ability of bacteria and other microorganisms to accumulate on the membranes used to filter water in treatment plants, according to a university news release.

“Just as plaque can build up inside arteries and reduce the flow of blood, bacteria and other microorganisms can over time attach and accumulate on water treatment membranes and along water pipes,” said So–Ryong Chae, post-doctoral fellow in Duke’s Civil and Environmental Engineering Department. “As the bacteria build up on these surfaces, they attract other organic matter, creating a biofilm that slowly builds up over time.”

The university’s laboratory research, which investigated Escherichia coli K12 buildup on water membranes, indicates that coating pipes and membranes with buckyballs could prevent this biofouling, Chae said.

A buckyball consists of 60 carbon atoms and is part of the carbon family known as fullerenes. These nanoparticles are named after Richard Buckminster Fuller, the inventor of the geodesic dome, which is a shape the buckyball resembles, the news release says.

The research shows that after 3 days, the membranes treated with buckyballs had an average of 20 bacterial colonies forming, while the untreated membranes had bacterial colonies “too numerous to count,” Chae said. Buckyballs impeded the ability of the bacteria to use oxygen to fuel its activities, the news release says.

Claudia Gunsch, assistant professor of civil engineering at Duke’s Pratt School of Engineering and senior member of the research team, explained that the “mechanisms involved are not well understood.” The researchers want to determine if buckyballs have any detrimental effects on the environment or to humans, which is one of many issues being studied at Duke’s Center for Environmental Implications of Nanotechnology, the release says.

“We need to figure out how resistant these coatings will be to long-term use,” Gunsch said. “If they can indeed prevent fouling, they will last longer. If they slough off over time, we need to know what the effects will be.”

The researchers also want to expand their research to test buckyballs’ effect on other bacteria. “The next stage of our research will be to see if these nanoparticles will have the same effects on bacteria commonly found in the environment or those in mixed microbial communities,” Chae said. “We also plan to build a small-scale version of a treatment plant in the lab to conduct these tests.”

The research was supported by the U.S. Office of Naval Research, the U.S. National Science Foundation, and the Korea Research Foundation (Seoul). 

Two-Step Process Creates Biofuel

University of Wisconsin—Madison researchers have developed a new two-step method that converts the cellulose in raw, untreated biomass into biofuel.

During the first step, cellulose is converted into the chemical 5-hydroxymethylfurfural (HMF), which then can be used to make various commodity chemicals, according to a university news release.

According to Ronald Raines, a professor in the university’s departments of biochemistry and chemistry, while other groups have determined some of the steps involved in converting biomass to HMF, their research shows “how to do the whole process in one step, starting with biomass itself.”

Raines worked with Joseph Binder, a doctoral candidate in the chemistry department, to develop a solvent system for the process. The patent-pending solvent and additives mixture dissolves cellulose to make the conversion to biofuel possible, the news release says. Raines and Binder use chemicals small enough to slip between lignin molecules that hold the cellulose together, where they work to dissolve the cellulose into its component pieces.

“This solvent system can dissolve cotton balls, which are pure cellulose,” Raines said. “And it’s a simple system — not corrosive, dangerous, expensive, or stinky.”

In the second step, the HMF is converted into the biofuel 2.5-dimethylfuran (DMF). Overall, 9% of the cellulose from the researchers’ corn stover samples was converted into biofuel, the news release says. (Corn stover consists of the corn-plant material that remains in the field following harvest.)

“The yield of DMF isn’t fabulous yet, but that second step hasn’t been optimized,” Raines said. DMF, already being used as a gasoline additive, has the same energy content as gasoline, doesn’t mix with water, and is compatible with the existing liquid transportation fuel infrastructure, the release says.

Raines and Binder also have tested this method using pine sawdust and are looking for other samples to try, the release says. “Our process is so general, I think we can make DMF or HMF out of any type of biomass,” Raines said.

The research was supported by the U.S. Department of Energy’s Great Lakes Bioenergy Research Center and a U.S. National Science Foundation Graduate Research Fellowship awarded to Binder.