Ecosmart: Could being green be easier than we thought?
By James R. Dukart
On a stifling hot summer day in New England, Dan Coughlin probably likes nothing better than the shade of a nearby nanotech fabrication laboratory.
It may look like Coughlin is heading for the shade of a tree, but to Coughlin - co-chairman of the nanotechnology initiative for the American Forest & Paper Association - the green, leafy structure he is parked beneath is nothing less than a complex, living nanotech lab. It may very well, in fact, hold keys to “green” manufacturing and supply chains through the use of nanotechnology.
“If you look at the processes within a tree, you can think of it as being your manufacturing process,” Coughlin said. At a cellular level, he explains, trees both host and manufacture a “cornucopia” of naturally-occurring nanomaterials - including the building blocks for a host of sugars, alpha and beta-celluloses and lignin, a complex polymer that binds to cellulose fibers and strengthens the cell walls of plants.
Coughlin argues that current manufacturing processes take the product of that tree - wood, mostly - and either turn it into finished products, such as paper and lumber, or burn it, spending its molecular energy as fuel to catalyze other processes. Nanotechnology promises to offer a different approach: the study and use of nanomaterials already in the tree - as production elements themselves or as examples of processes that can reduce the use of raw materials. Using fewer raw materials means cutting pollution and energy costs, and in turn protecting the environment.
The American Forest & Paper Association believes so strongly in nanotechnology that it has created a roadmap for nanotech in the forests and committed $40 to $60 million per year to research and development marrying trees and nanotech. Early successes include the separation of lignin in lumber production for use as a replacement for petroleum in plastics manufacturing.
Another green chemistry and nanotechnology proponent, Jim Hutchison, director of the Materials Science Institute at the University of Oregon and leader of the Safer Nanomaterials and Nanomanufacturing Initiative at the Oregon Nanoscience and Microtechnologies Institute, targets semiconductor manufacturing for greening. Citing a calculation from researchers at the United Nations and National Science Foundation, Hutchison notes that traditional manufacturing methods require some 1.7 kilograms of energy and raw material to produce a typical 2-gram DRAM chip. “The process might take 10 or 11 steps, and nearly everything you see is thrown away,” Hutchison says. “The photoresist, cleaning solutions, solvents, even most of the metal is discarded.”
Contrast that to biomolecular nanolithography, something the Hutchison lab is actively working on. The lab uses self-assembly of nanoparticles on biopolymeric (DNA) scaffolds to form lines and more complex patterns. The resulting molecularly integrated nanocircuits, Hutchison notes, contain all raw materials used in production - with zero waste.
Another way to use nanotechnology to green up manufacturing processes is to alter the agents, solvents or reagents used in processes. Hutchison’s lab has patented a method for producing gold nanoparticles stabilized with triphenylphosphine, using water as a solvent rather than benzene. The result of this change in reagents is a faster, cleaner and far less expensive manufacturing process - the lab can now produce the particles for $500 per gram, dramatically less than what it had cost to have them made using traditional methods.
“The place to start is to green up the existing process,” Hutchison said. “What agents are you using? Can you use a catalytic process at room temperature? Can you use microwave heating instead of thermal heating? Are you incorporating all the atoms of the material or are many being wasted in the process?”
Barbara Karn, a visiting scientist at the Woodrow Wilson International Center for Scholars Project on Emerging Nanotechnologies, sees big things ahead in the way catalysts are used to bring nanotechnology to manufacturing. “In the 20th Century, catalysts were being made more efficient,” Karn said. “With nanotechnology, they can be made more specific.”
John Warner, director of the Center for Green Chemistry at the University of Massachusetts Lowell, sees another benefit to the use of more targeted catalysts and benign reagents and solvents: the ability to manufacture at much lower temperatures, saving both the energy needed to heat chemical reactions and the waste heat generated by the processes.
“Look at the mineralization of bones and seashells, and they don’t need extreme heat,” Warner said. “Using bioinspiration we should be able to figure out how to do things at room temperature that are now being done at heats of 500 degrees Celsius and higher.”
One of Warner’s key research areas is noncovalent derivatization, essentially the use of natural forces to construct materials rather than using heat or light to break things apart. “We have to focus on the non-obliterative technologies,” Warner said. “Instead of the typical (processes), where you shine a laser on something and blow something else away, we want to look at the molecular level and create from the bottom up.”
Another alluring combination of nanostech research and green manufacturing is the promise of true life-cycle product planning. Hutchison refers to Sea-Nine, a marine antifoulant used on the hulls of ships that has been specifically designed to degrade into environmentally benign substances as it flakes off into seawater.
While Sea-Nine is more a product of molecular engineering than nanotech, Hutchison sees excellent life-cycle management possibilities using nano. “Hopefully we can make nanomaterials that serve some purpose out in the environment but are designed so they rapidly degrade into harmless materials when the end of their life occurs,” he said.
Karn says true life-cycle management follows a product from manufacture through use and disposal. Nanoscale products, she notes, have an inherent advantage in terms of waste reduction. “Pollution is waste,” she said. “Say you take a dendrimer and put a drug inside it and decorate it with something that is specific to the target cells. Making the drug that specific is an aid to the environment.” It’s one among an increasing number of examples where economic and environmental concerns are in synch.
American Forest & Paper Association
Center for Green Chemistry, University of Massachusetts Lowell
Wilson Center Project on Emerging Nanotechnologies
Safer Nanomaterials and Nanomanufacturing Initiative