In some scientific circles, the metal boron is viewed as an underachiever. Best known for its role in the household cleaning compound borax, boron is also touted by engineers as a potential energy source capable of generating more heat than gasoline or jet fuel. The challenge to date, however, has been to harness its latent power.
"Boron is the most energetic metal, with the highest energy per gram. It has the potential to be used as an additive in missile propellants, explosives and in compounds that release chemicals to destroy biological weapons. But it combusts slowly and takes a long time to ignite," notes Kerri-Lee Chintersingh-Dinnall, a Ph.D. student in chemical engineering who is exploring methods to make boron burn faster and more easily.
She recently received a vote of confidence. At a meeting held by the U.S. Defense Threat Reduction Agency to review ongoing research on materials capable of defeating or disabling weapons such as anthrax, Chintersingh-Dinnall won the poster competition for her work in the lab adding iron to boron by a method called ball-milling to accelerate its combustion. Later this year, she will try different techniques to incorporate other metals with boron and add pressure to the combustion chamber to see if that, too, speeds up the process.
"Our results are promising. We found that pre-treating boron with solvents such as acetonitrile improves ignition and adding iron speeds up boron burning in air and steam," she says, noting of boron's potential, "It's mined here in the U.S., it's cheap and it's a hard metal powder that can potentially deliver more energy in a smaller package than existing fuels. It's also environmentally safe to use."
Scientists who focus on energetic materials have an enduring interest in boron's capacity. When it reacts with oxygen, its chemical bonds break and reform to produce boron oxide, releasing a third more energy for the same weight as diesel fuel, for example.
"It's the best solid fuel which is not toxic," notes Edward Dreyzin, distinguished professor of chemical engineering and Chintersingh-Dinnall's adviser. "The trick is to make it burn fast enough that it becomes practical to use. This is a longstanding problem. Kerri's approach to dope boron with small amounts of metal additives is interesting because it does not diminish its energetic potential, but is already proven to accelerate its combustion."
Chintersingh-Dinnall says her research on boron is sparked by "the current challenges the energy community faces" and by her longstanding interest, dating back to her undergraduate years in Jamaica, in alternatives to fossil fuels, such as castor oil and wastewater algae. Boron intrigues her in particular because of its potential use in many applications, provided that its challenges are mitigated.
She will present her work on boron doping at the American Institute of Chemical Engineers Annual Meeting and Materials Research Symposium later this year.