Making materials the environmental way.

With hazardous waste becoming increasingly expensive to treat, chemical companies are looking for new ways to synthesize their products without generating toxic by-products. Researchers at AlliedSignal, Inc., in Des Plaines, Ill., say they've found a method for synthesizing conductive polyaniline - a tough material used in conductive films, coatings, and batteries - that produces only water as a side-product.

The new technique, which uses a biological catalyst, could help reduce the production of ammonium sulfate, by tonnage the chemical industry's number-one waste product, says AlliedSignal's Haya Zemel.

The standard process for making conductive polyaniline creates large amounts of ammonium sulfate and leaves strong acid residues. "A biological method that produces no waste would be very attractive," says Zemel. Using hydrogen peroxide and horseradish peroxidase enzyme at a very acidic pH of 3, her group catalyzed a completely clean conversion of aniline to conductive polyaniline. They are now working to improve the 60- to 90-percent yield, boost the product's conductivity, and find a cheaper form of the peroxidase enzyme.