ChemMatters, DECEMBER 1999 9

Chemistry, the source of manyof the products we enjoy andtake for granted, earns well-

deserved credit for the high standardof living we enjoy today. We canthank the efforts of chemists for thegasoline that powers our cars, thepain relievers we take for ourheadaches, Styrofoam cups thatkeep our hot drinks hot and our colddrinks cold, and even the paper thismagazine is printed on. But it is alsotrue that the production of these andother materials can have undesirableenvironmental effects. Over the pastfew decades, news reports havedescribed numerous examples ofindustrial processes that cause harmby polluting our land, water, and air.Damage to the environment and tohuman health as a result of chemicalmanufacturing remains a majorglobal concern.

An effort to ensure a safer,cleaner environment for the 21stcentury, the green chemistry move-ment has been gaining momentum inrecent years. Basically, green chem-istry is an effort toward eliminatingpollution by making chemical prod-ucts that do not harm either ourhealth or the environment, and byusing production processes that

reduce or eliminate hazardous chem-icals. Green chemistry prevents pol-lution at its source rather thancleaning up the mess later.

Think about it this way. Weknow it is better to maintain ourgood health in the first place than totake medicines after we get sick.Chemists are thinking about chemi-cal processes in the same way. Theyare using their knowledge of chem-istry to analyze the current ways ofmaking things. By doing so, they aredesigning safer and cleanerapproaches to manufacturing theproducts we need.

To promote these efforts and torecognize the most successful ones,President Clinton announced theestablishment of the PresidentialGreen Chemistry Challenge Awardsin 1995. On behalf of the President,the Environmental Protection Agency(EPA) has presented awards eachyear since 1996. As Dr. Paul Anastasof the EPA Office of Pollution Preven-tion and Toxics explains, “The GreenChemistry Challenge Awards Pro-gram provides national recognitionfor chemistry that incorporates theprinciples of green chemistry intochemical design, manufacture, anduse.” Today, these awards are the

only Presidential-level recognition ofaccomplishments in the chemicalsciences.

The PyrocoolAward: Puttingout fires thegreen way

At one time, water virtually wasthe only chemical that firefightershad to put out fires. However, somefires cannot be easily extinguishedby using water. When materials likeoil ignite, the use of water can actu-ally cause the fire to spread. Conse-quently, in the 1960s, the U.S. Navydeveloped fire-blanketing chemicalfoams to combat fires from oil spills.Other types of foams were designedto put out fires resulting from woodor paper. Halon compounds—chemi-cals such as bromotrifluoromethane(CF3Br)—are useful on fires inrooms with electronic equipment,like computer centers, because theyleave no residues upon evaporation.All of these new substances haveimproved fire fighting, but they havealso exacted a price on the environ-ment.

By Mary Ann Ryan

Green Chemistry

Benign by DesignBenign by Design

PH

OT

O C

OU

RT

ES

Y O

F C

AN

OLA

CO

UN

CIL

OF

CA

NA

DA

continues on next page

CM pages December99 8/6/01 11:14 AM Page 9

10 ChemMatters, DECEMBER 1999

The millions of tons of chemical fire-fighting agents used worldwide have dis-charged into the environment toxic substanceslike hydrofluoric acid (HF) and other danger-ous fluorine-containing compounds. Some-times, these chemical foams contaminatewater supplies, causing wastewater treatmentsystems to fail by preventing bacteria frombreaking down waste in the water. Some fire-fighting chemicals lead to depletion of the pro-tective layer of ozone in the Earth’s strato-sphere—a layer that helps to block out harm-ful ultraviolet radiation that can cause skincancer and cataracts.

In response to this serious problem,Pyrocool Technologies, Inc., a small companyin Lynchburg, VA, invented a foam called Pyro-cool F.E.F. (Fire Extinguishing Foam) thatincludes none of the harmful substances foundin other fire-fighting materials. The com-pounds that make up Pyrocool F.E.F. arerapidly biodegradable or easily digested bybacteria in the environment to simpler sub-stances. In addition, they are nontoxic andwork faster to put out fires than other extin-guishing compounds. And the foam works at alower concentration than is needed for othersubstances, so that less is required to do aneffective job. For developing this valuable newproduct for putting out fires without damage tothe environment, Pyrocool received a 1998Presidential Green Chemistry Challenge Award.

The ideal startingmaterial or “feedstock”for large-scale chemicalmanufacturing of prod-ucts would be some-thing that is renewable,whose use, therefore,would not deplete valu-able natural resources.Yet the vast majority ofchemical products madein the United Statestoday are not from suchsources, but rather areultimately derived frompetroleum reserves thathave taken millions of years to build up in theearth. Realistically, we cannot consider oilreserves to be renewable. Furthermore, somepetroleum-based feedstocks are hazardous.Benzene (C6H6), for example, is a carcinogen.Consequently, efforts have been under way toidentify renewable feedstocks such as thosefrom biological sources. Cellulose, starch, andsugars are examples of plant-based materialsthat can serve as renewable resources.

The Biofine Company of Waltham, MA,recognized the impor-tance of using renew-able feedstocks that areneedlessly going towaste at present.Biofine received a 1999Presidential GreenChemistry Award fordeveloping a processthat converts wasteproducts containing cel-lulose into a chemicalcalled levulinic acid(C5H8O3). A promisingchemical building blockthat serves as the start-ing material for a widevariety of commercialchemicals, levulinic acidhas already been usedto develop a biodegrad-able herbicide, an eco-

nomical fuel additive that makesgasoline burn more efficiently,and new biodegradable poly-mers. The Biofine process pro-duces levulinic acid for afraction of the cost of alternativemethods for making it.

According to the BiofineCompany, municipal solid wasteconsists of 60–70% cellulose inthe form of cardboard, paper,and wood, much of which is notrecyclable. Such waste is gener-ally dumped in landfills, inciner-ated, or composted—allmethods of disposal that add lit-tle value, can be costly, and forthe most part, aren’t very popu-lar. Who wants a smelly inciner-ator or a landfill in theirneighborhood? Biofine’s process

converts this waste into valuable products.Conversion of paper mill sludge—cellulose-containing waste that results from the produc-tion of paper—into levulinic acid could helppaper mills to reduce their waste discharge tonearly zero.

The Dow award: Polystyrene foamgoes green

Polystyrene foam, made by the DowChemical Company as Styrofoam, is the mate-rial that is often used for carry-out coffeecups, meat, and poultry trays, and the moldedpackaging that surrounds electronic equip-ment. The foam has good thermal insulationproperties, is moisture resistant, and can berecycled.

Before being converted into the foampackaging we know, polystyrene is a hard,brittle, plastic material. The manufacturingprocess used to transform it requires a blow-ing agent—a substance that is forced throughmolten polystyrene and then expands to formbubbles or gas pockets in the polystyrene. It isthe high percentage of trapped gas in the final,cooled product—about 95% gas and 5% poly-styrene—that results in the lightweight foamused to make food trays or containers.

The blowing agents historically used formaking polystyrene foam were chlorofluoro-carbons (CFCs), in particular, one called

The Biofine Award: Turningpulpy waste products intosomething green

Pyrocool Fire Extinguishing Foam puts out fires without releasing harmfulgases into the atmosphere that can deplete the planet’s protective ozonelayer.

COURTESY OF PYROCOOL TECHNOLOGIES, INC.

COURTESY OF PYROCOOL TECHNOLOGIES, INC.

CM pages December99 8/6/01 11:14 AM Page 10

ChemMatters, DECEMBER 1999 11

CFC-12, which has the chemical formulaCCl2F2. These compounds had a number ofpractical advantages; for example, they werecost-effective, nonflammable, and safe to han-dle. However, CFCs were found to harm theenvironment in a manner similar to some ofthe first fire-fighting foams noted earlier—by

causing ozone depletion in the earth’supper atmosphere. Consequently, theproduction of CFC-12 in the UnitedStates was banned in 1995. Severalreplacement compounds, such asHCFCs (hydrochlorofluorocarbons) orpentane (C5H12), were found to reducethe environmental risk to some extent,but still were not problem-free.

To eliminate the use of environ-mentally damaging chemicals, Dowdeveloped a new process for which thecompany received a Presidential GreenChemistry Award in 1996. This innova-

tive process uses 100% carbon dioxide (CO2)as a blowing agent. CO2 is a safe, readilyavailable substance that does not deplete theozone layer and is cost-effective. Althoughoverproduction of CO2 can lead to globalwarming, Dow’s process avoids this potentialproblem by using only CO2 that is already

available—either from natural gas wells orbyproducts from plants that produce ammo-nia. No additional CO2 is generated to makethe polystyrene foam. Dow estimates that theuse of CO2 as a blowing agent has reducedthe use of CFCs and other harmful chemicalagents by 3.5 million pounds per year.

Toward a greenercentury

The above examples give only a hint ofthe many ways in which green chemistry candeliver results that are scientifically sound,cost effective, and safe. Not only is greenchemistry the environmentally responsiblething to do, it is also becoming the most prac-tical thing for businesses to do. The costs ofcleaning up hazardous wastes have grownsubstantially as companies grapple with thehost of federal, state, and local environmentallaws enacted since 1970. If companies canidentify cleaner processes that are also cost-effective, they can become more profitable byreducing costs of environmental cleanup. Inother words, “green” can be practical, prof-itable, and protective of the planet.

Editor’s Note This article is the first of a seriesof articles on green chemistry that will appearin futures issues of ChemMatters. Watch formore stories about chemists who havedesigned ways to produce the things we needwithout polluting the planet. Know some goodexamples in your community? Write to us atchemmatters@acs.org.

Mary Ann Ryan is a science writer and former chem-istry teacher. She serves as coordinator for a projectjointly sponsored by the American Chemical Societyand EPA to develop educational materials on greenchemistry.

REFERENCESDagani, R. Green Winners. Chem. & Eng.

News 1999, 77 (27), pp 30–32.Morse, P. M. Taking a Measure of

Sustainability. Chem. & Eng. News 1999,77 (30), pp 19–22.

RELATED ARTICLESDowney, C. Biodegradable Bags. ChemMatters

1991, 9 (3), pp 4–6.When Good Ideas Gel. ChemMatters 1992, 10

(4), pp 14–15.

Inexpensiveindustrialsolvent

Nontoxicweed killerfor lawnsAlternative

fuelcomponent

Fuelextender

oxygenate

Diphenolicacid forplastics

manufacture

Inexpensivenatural

herbicide forgrain crops

Succinicacid

solvents/plastics

NREL3-step

synthesisPNNL

hydrogenationprocess

LevulinicAcid

Bioline 2-stagehigh temperature

dilute acidhydrolysis process

Methyltetrahydrofuran

Delta-aminolevulinic acid

Phenol reactionOxidation

Paper mill sludgeor other biomass

The Biofine Company found a way to turnthe sludge from paper manufactuing into arenewable feedstock for a variety of cleanproducts.

You probably haven’t noticed, but Styrofoam has gotten alot greener. Dow chemists have replaced environmentallyharmful CFCs with CO2 to make the foam.

COUR

TESY

OF

BIOF

INE

AND

NATI

ONAL

REN

EWAB

LE E

NERG

Y LA

BORA

TORY

(NRE

L)

CM pages December99 8/6/01 11:14 AM Page 11