| VOL. 23, NO. 17||MARCH 6, 1998 |
Scientists Adapt Detergents for Medical, Everyday Use
BY BOB NELSON
|Among the scientists working to find new uses for novel detergents are, from left: Carl Gryte; Ponisseril Somasundaran; Paul Duby; Nicholas Turro, and Alan West. Record Photo by Eileen Barroso.|
hemists and engineers at Columbia are finding dozens of new uses for a class of more effective, less polluting detergents, using industrial materials based on sugar.
The materials, called surfactants, have been developed by chemists at European and American chemical companies, but are being adapted at Columbia for novel uses in households, medicine and industry, from getting clothes cleaner to lubricating titanium implants.
The research comes at a crucial time for consumer products companies, which are seeking replacements for synthetic detergents that are not easily degraded and require additives to soften hard water.
Work at Columbia is focusing on molecular analysis of the materials to understand their novel properties, testing them for new uses and attaching molecules of them together in new ways to create super-cleaning agents.
A key industry advance has been the creation of surface-acting polyglucosides, short chains of two glucose molecules with attached hydrocarbon side groups, that are extremely effective at dissolving grease and can, for example, clean soils contaminated by gasoline. The sugar-based polymers are milder than soaps, can be used in personal care products, are easily digested by microbes, are tolerant of hard water and leave no trace in the environment.
There is no reason to restrict these new materials to industrial use, said Ponisseril Somasundaran, LaVon D. Krumb Professor of Mineral Engineering in the Henry Krumb School of Mines at Columbia. We believe they have better cleansing properties than todays household products, and are equal or better in biodegradability.
The National Science Foundation notified Columbia in late February that it would fund the Universitys $500,000 proposal over five years for its Industry/University Center for Surfactants, to be based in the Fu Foundation School of Engineering and Applied Science.
To complete the $2.3 million, five-year budget for the center, Columbia will also receive a total of $350,000 annually from 15 corporate partners it has so far recruited, including Akzo Nobel Corp., ARCO Exploration & Production Technology, CIBA Specialty Chemicals, Colgate-Palmolive Co., Halliburton Energy Services, Henkel Corp., International Specialty Products, LeaRonal Inc., Rhone Poulenc Inc., Rohm & Haas Co. and Unilever Research U.S.
In addition to Somasundaran, who is also director of the Langmuir Center for Colloids and Interfaces at Columbia and principal investigator of the NSF grant, researchers affiliated with the center are Paul Duby, professor of mineral engineering; Carl Gryte, professor of chemical engineering and applied chemistry; Brian Pethica, adjunct senior research scientist; Nicholas Turro, William P. Schweitzer Professor of Chemistry, and Alan West, associate professor of chemical engineering and applied chemistry.
Surfactantssurface-active compounds such as soaps and detergentshave at least one hydrophobic and one hydrophilic region; the former binds to insoluble grease or dirt, while the latter provides a region that can interact with water.
Surfactants coat the surface of grease or dirt particles, breaking them up to be flushed away, or can bind to artificial polymers and hold them in suspension for use as paints, advanced lubricants and anticorrosive coatings.
Other uses are in pharmaceuticals, cosmetics, food processing, advanced ceramics, micro-electronics, liquid crystals, fuels, photographic films and biotechnology.
Researchers at Columbia are trying to understand the properties of the new surfactants by conducting molecular-level studies using advanced chemical techniques such as fluorescence spectroscopy and electron spin resonance spectroscopy.
They are also developing new molecular structures by adding novel surfactants to polymers. The polymers can then be folded to bring the surfactants hydrophobic regions together, forming a micelle, or artificially ordered region, that would suck up grease like a sponge, Somasundaran said.
Columbia will collaborate with Unilever Research to develop polyglucoside-based antimicrobial agents that would dissolve the protective sheath around bacteria.
Such agents have been shown to adsorb well to titanium surfaces and would provide an ideal sterile lubricant for implanted prostheses.
ARCO and Henkel Corp. will also help develop the sugar-based materials.
In addition to the polyglucosides, researchers at the center will develop pyrrolidones, a class of five-membered ring hydrocarbons that are soluble in both organic and inorganic compounds and thus are superior detergents.
When a small amount of pyrrolidone is added to oil that has particles suspended in it, for example, the particles clump together, allowing purified oil to be removed from the mixture.
A little bit of it performs magic with effluents containing undesirable particles, Somasundaran said.
Columbia has filed a patent application covering novel applications of N-alkyl-2-pyrrolidones.
Soaps are long-chain fatty acids that have been modified by strong bases, which add hydroxyl ions that attract water.
Early cultures discovered soaps when fats dripped onto wood ashes that contain bases. During World War II, German chemists formulated branched-chain synthetic soaps such as alkyl benzene sulfonates, which, like soap, functioned well in hard water by precipitating the calcium ions that make water hard.
Branched-chain synthetics, which microbes cant digest, caused foaming in river water and in contaminated well water.
So industry began producing straight-chain alkyl benzene sulfonates, single chains of hydrocarbons attached to a benzene ring and a sulfonate group, which are still the laundry workhorse.
But straight-chain synthetics dont efficiently precipitate calcium ions, so chemists had to add phosphate softeners, which also caused the eutrification of lakes and rivers.
American companies now add water softeners such as sodium carbonate, or washing soda, to laundry products.