Susan Hennessey, EG 2001M, of Avondale, Pa., is using biotechnology to make cleaning products that are safer for the environment.

A chemical engineer with the DuPont Co., Hennessey is working on a process that utilizes biocatalysts and encapsulation to make biodegradable solvents useful for cleaning metals and computer circuit boards.

A catalyst increases the rate of a chemical reaction without itself undergoing any change. Encapsulation is the process in which biological substances--in this case bacterial cells--are enclosed in gel beads so they can serve as catalysts and then be recycled to be used again and again.

"Encapsulation has been widely written about and applied in academia, but it's rarely been used in manufacturing," Hennessey says. "In situations where a biocatalyst is superior to a chemical catalyst, encapsulation can make it cost effective."

Biocatalysts are more specific, creating less waste than chemical catalysts, she says, and the enzymes react in water at lower temperatures, making the reactions more stable and less toxic.

Currently, Hennessey is working on a more environmentally friendly cleaning product for metals. It is a biodegradable, clear colorless liquid with a mild odor, good chemical stability and low toxicity. It also has better solvency properties that make it a more efficient product, she says.

The bacterial cells encapsulated in a gel cause a reaction that converts MGN, a co-product from the manufacture of nylon, into a unique product that DuPont has named Xolvene.

Before she joined the biological science and engineering group working on enzymatic reactions in 2000, Hennessey worked in crop protection and central research and development at DuPont. That group used encapsulation to make two new herbicides. The new encapsulation techniques reduced the amount of catalyst waste by a thousandfold, simply by changing from a heavy metal catalyst to the biocatalyst, she says.

With an undergraduate degree from Widener University, Hennessey has worked at DuPont for 16 years. She started taking chemical engineering classes at UD in the fall of 1994. At that time, she was working full-time at DuPont and was the mother of two. She had her third child in 1996, when she was almost halfway through completing her degree.

With her busy schedule, she took one class during the fall and spring semesters. She also opted to pursue a nonthesis master's degree.

Hennessey says that without help from Engineering Outreach director Kathy Werrell, she probably would have not been able to complete her degree.

"The department was extremely helpful in allowing me to work and attend class at the same time," she says.

She says her degree gave her a deeper understanding of the principles and theories of chemical engineering, which have made her a better engineer because she can more easily tackle projects.

--Tracy Ortiz, AS 2003