Sustainability at the ACS Green Chemistry & Engineering Conference

1. Prevent waste: Design chemical syntheses to prevent waste, leaving no waste to treat or clean up.
2. Design safer chemicals and products: Design chemical products to be fully effective, yet have little or no toxicity.
3. Design less hazardous chemical syntheses: Design syntheses to use and generate substances with little or no toxicity to humans and the environment.
4. Use renewable feedstock: Use raw materials and feedstock that are renewable rather than depleting. Renewable feedstock are often made from agricultural products or are the waste of other processes; depleting feedstock are made from fossil fuels (petroleum, natural gas, or coal) or are mined.
5. Use catalysts, not stoichiometric reagents: Minimize waste by using catalytic reactions. Catalysts are used in small amounts and can carry out a single reaction many times. They are preferable to stoichiometric reagents, which are used in excess and work only once.
6. Avoid chemical derivatives: Avoid using blocking or protecting groups or any temporary modifications if possible. Derivatives use additional reagents and generate waste.
7. Maximize atom economy: Design syntheses so that the final product contains the maximum proportion of the starting materials. There should be few, if any, wasted atoms.
8. Use safer solvents and reaction conditions: Avoid using solvents, separation agents, or other auxiliary chemicals. If these chemicals are necessary, use innocuous chemicals. If a solvent is necessary, water is a good medium as well as certain eco-friendly solvents that do not contribute to smog formation or destroy the ozone.
9. Increase energy efficiency: Run chemical reactions at ambient temperature and pressure whenever possible.
10. Design chemicals and products to degrade after use: Design chemical products to break down to innocuous substances after use so that they do not accumulate in the environment.
11. Analyze in real time to prevent pollution: Include in-process real-time monitoring and control during syntheses to minimize or eliminate the formation of byproducts.
12. Minimize the potential for accidents: Design chemicals and their forms (solid, liquid, or gas) to minimize the potential for chemical accidents including explosions, fires, and releases to the environment.

Nearly 500 attendees came to College Park, Maryland on June 23-25 to the 2009 ACS Green Chemistry and Engineering Conference to hear speakers on 7 different tracks as well as to peruse poster sessions and notable keynote speakers Len Sauers (Procter & Gamble) and Jean-Michel Cousteau (The Cousteau Society). Here are a few of the highlights:

"Chlorantraniliprole: Design of Green Chemistry for Insect Control," George P. Lahm, DuPont Crop Protection Dr. Lahm presented a profile of the chemical chlorantraniliprole that is used as a pesticide. Lahm showed that this product worked well with the surrounding environment—including beneficial like bees and spiders—while still retaining a potent dose of poison to certain insects (in this case—caterpillars). Dow claims that the chemical is in fact "one of the least toxic and most active chemical insecticides ever discovered."

"Performance of Carbon-Neutral Rice Hull Ash as a Supplementary Cementitious Material in Portland Cement Mortars," Prasad Rangaraju, Clemson University One solution to the gray world of standard Portland cement was presented by R.K. Vempati and his colleague Prasad Rangaraju from Clemson University. The researchers propose using rice hull ash (RHA) to dramatically whiten cement. RHA is made from the controlled combustion of rice hulls—the hard outsides of rice that must be removed before we can cook and consume rice. Drs. Vempati and Rangaraju had managed to substitute 20% by mass of cement with RHA. They saw significant compressive strength as well as a substantially whiter end product (thanks to biogenic silica from the rice hull). The end product is described as carbon neutral, which is of course, of great importance to today's modern building infrastructure. The researchers point out that the production of one ton of regular cement produces one ton of CO₂ and that there is 1 yard³ per person of cement produced every year—making concrete the second most widely used material on earth (water is the first). So by taking a second look at how we use and produce building materials, there's much more to gain than just the beautification of our cities and highways.

"Dissolvine GL: A New, Biodegradable Chelating Agent with an Excellent Safety Profile," Edwin Bisinger Jr., SHERA Americas
Chelates are chemical agents that interact with metal ions, often allowing for increased solubility of the metal ion. Current chelate substances are based on aminocarboxylic acids (e.g. EDTA) and also on phosphates (tripolyphosphates) and are used in many types of cleaners such as those used in automatic dishwashers.  Unfortunately, because EDTA is not readily biodegradable and because phosphates are known to cause eutrophication in natural waters, the current chelating substances are viewed as environmentally unfriendly. In response to these concerns, Dr. Bisinger and his team at AzkoNobel have developed a readily biodegradable chelating agent that is manufactured principally from a renewable feedstock. It's hoped that this new chelate, tetrasodium L-glutamic acid, N,N-diacetic acid (GLDA), will emerge on the marketplace to replace phosphates in detergents as a safer and greener alternative.

According to Bisinger, the major advantage of GLDA relates to its demonstrated safety profile. A comprehensive set of toxicity tests reveal that GLDA has excellent safety properties with regard to human health and ecological effects. GLDA is manufactured monosodium glutamate (MSG)—which is itself made from the fermentation of readily available corn sugars—and is a renewable and biodegradable material. The carbon content of other chelating agents, like EDTA, is fossil based, while the carbon source of GLDA is primarily biobased. In addition, GLDA has an excellent safety profile with respect to both human health and ecological effects.