Overview of Nanotechnology
Quak Foo Lee
M.A.Sc., B.A.Sc. (Chem. Eng.)
Ph.D. Candidate
Department of Chemical and Biological Engineering

 

What is Nanotechnology? 

What is nanotechnology? Nanotechnology is manufacturing at the molecular level - building things from molecular or nano-scale components. A nanometer is one billionth of a meter (3 - 4 atoms wide). Nanotechnology proposes the construction of novel nanoscale devices possessing extraordinary properties. Through the development of such instruments and techniques it is becoming possible to study and manipulate individual atoms. 

What's agreed about nanotechnology? That it is a technology in its infancy, and that it holds the potential to change everything. What's disagreed is nearly everything else: what it will make possible, when those possibilities will be realized and even whether to pursue nanotech at all. People also disagree about what nanotechnology is: Are polymers nanotechnology? What about gene splicing? And many companies tack "nano" to their name with little science to back them up.

Here every guide to nanotechnology pauses to explain the word's exotic prefix. Derived from the Greek word for midget, "nano" means 10^-9, a billionth part. A nanometer (abbreviated nm), for example, is one billionth of a meter. An atom measures about one-third of a nanometer. The diameter of a human hair—a measurement notable, perhaps, as nanotechnology's greatest cliché—is about 200,000 nm.

Having explained the prefix, it wouldn't do to overlook the workaday root. Nanotechnology is not just the study of the very small, it is technology: the practical application of that knowledge. Since Democritus, scientists have pondered atoms, but only in the last few decades have they begun to pick them up and put them where they want.

Nanoparticles Prove Irresistible for Cleanup of Industrial Waste
By Kyle James
Small Times Correspndent
July 23, 2003

It was the industrial age that brought increased exposure to dangerous heavy metals like lead, mercury or arsenic as factories dumped contaminated wastewater into rivers and oceans. It is the nanotechnology age that could mark the end of this particular toxic chapter.

A team of scientists and manufacturers from Germany, Ireland and the United Kingdom has developed a process that uses nanoparticles to draw heavy metals out of industrial wasterwater with a little help from simple magnetism.

The principle is that the iron oxide nanoparticles have set in a glass matrix to create superparamagnetic composite particles (SPMC) -- micron and submicron-size particles with magnetic properties that heavy metals simply find irresistible.

The SPMC are introduced into wastewater and attract the heavy metals present there. Then the water is passed through a magnetic field and the fully laden SPMC are drawn out of the flow. 

After removal from the water, the heavy metals can be detached from the SMPC through a chemical process. The result is a highly concentrated sludge.

The advantages of the particles treatment method, as opposed to traditional processes like chemical or precipitation treatments, is that it is possible to achieve very high levels of purity at the end. That is expecially important when the metals in question are highly toxic ones such as mercury or lead.

Researchers are devising molecular structures that identify, attract, and react with toxic waste far more efficiently than conventional treatments—and leave behind only harmless byproducts.

The U.S. Environmental Protection Agency is providing $7 million in R&D funding for nanoscale solutions to big pollution problems, from groundwater toxins to air pollution to soil contamination. That’s a small amount of money when compared with, say, the $2 billion in federal funds earmarked for the Clean Coal initiative, which is aimed at using less exotic methods to reduce pollution caused by the mining and burning of coal. But even with relatively modest level of federal support, the progress in green nanotechnology at the 16 universities and 11 companies conducting the research has been rapid.

One of the first of these technologies to prove itself in field trials was developed by Wei-xian Zhang, a professor of civil and environmental engineering at Lehigh University. Zhang has developed a nanoscale material that, when applied to water contaminated with carcinogenic solvents used in industrial processes, converts the contaminants into harmless byproducts. Treatment of these toxic materials now typically involves pumping contaminated water into deep trenches, then seeding the water with millimeter-sized iron filings; as the iron corrodes, it react with the waste and converts it to safe hydrocarbons and chlorides. But that process is expensive and inefficient—and can take years.

“In the conventional method the reaction often will go halfway and stop, because there isn’t enough energy to complete the reaction,” says Zhang. “So you’re left with tons of iron filings in the water, which creates another hazard. With the nanoparticles the reactions tend to be very complete. The material all gets used up.”

Zhang’s method has also been found effective for removing cyanide, and may be adaptable for use in soil treatment and for nuclear waste treatment. One obstacle remains: it takes two weeks to grow enough material in Zhang’s lab even for a limited field trial. “The key to commercializing this process will be to make the material in a large enough quantity to get economies of scale,” says Zhang, who is in discussions with chemical companies and expects to have industrial partners signed on to do just that by the end of the year. Other nanotechnology research projects being funded by the EPA might lead to particles that treat automobile exhaust gas at the source, even before it disperses into the atmosphere, or the development of highly sensitive sensors that can detect minute amounts of toxic material. As with Zhang’s research, these projects seek to exploit the greater reactivity that smaller-sized molecules will provide, as well as the ability to design these molecules in a manner that is uniquely suited to attacking a particular pollution problem.

Ultimately, the real promise of nanotechnology may come not only through treating pollution, but by avoiding its creation in the first place, replacing existing manufacturing processes with cleaner, nano-based alternatives. Intematix, for example, a small company based in Moraga, CA, is developing a method for adding carbon nanotubes to plastics that will give these plastics the properties of a metal. This will allow plastic parts of the automobile to be painted without requiring toxic solvents to bind the paint to the plastic. If the company succeeds in making the process economical for automobile manufacturers to adopt, it will reduce the amount of polluting material used for each car coming down the assembly line.

“Toxic cleanup is useful, but is not really where I set my sights for this technology,” says Tina Masciangioli, a technology policy fellow with National Center for Environmental Research, the group in the EPA that monitors the progress of fund recipients. “I like to look further ahead, where we learn to make things that don’t pollute to begin with. That’s where the potential benefits are just tremendous.”

 

Protein Traps Nanoparticle
Technology Research News  June, 10, 2003

Proteins come in many handy shapes and sizes, which makes them major players in biological systems. Researchers from the University of Tokyo in Japan have adapted a tubular bacterial protein for technological applications by coaxing it to combine with individual luminescent semiconductor nanoparticles.

In bacteria, this chaperonin protein takes in and re-folds denatured proteins in order to return them to their original useful shapes.

Cadmium sulfite nanoparticles emit light as long as they are isolated from each other; encasing the nanoparticles in the protein keeps the tiny particles apart. The biological fuel molecule ATP releases the nanoparticles from the protein tubes, freeing the particles to clump together, which quenches the light.

The protein-nanoparticle combination could be used to detect ATP, according to the researchers. The researchers are working on using the combination to detect specific ATP concentrations. They are also working on coaxing the protein to capture and release organic molecules. This ability would make the proteins good candidates for drug carriers, according to the researchers.

The protein-nanoparticle combination could be used in practical applications in three to five years, according to the researchers. The work is scheduled to appear in the June 5, 2003 issue of Nature.

 

Material Eases Hydrogen Storage
Technology Research News  May 20, 2003

One of the biggest challenges to using hydrogen as a fuel is finding a way to store it. The lighter-than-air gas makes the perfect fuel—it contains three times the energy of liquid hydrocarbons and when it reacts with oxygen to produce energy the only byproduct is water—but it isn't easy to contain.

Today's hydrogen storage materials hold 2 to 4 percent of their weight in hydrogen, considerably short of the 6.5 percent Department of Energy goal for using hydrogen as an automobile fuel.

Researchers from the University of Michigan, the University of California at Santa Barbara, the University of South Florida and Arizona State University have discovered a new class of materials, dubbed metal-organic frameworks, that are simple and inexpensive to manufacture and have the potential to reach the 6.5 percent mark.

The materials also take up and give up hydrogen more easily than current hydrogen storage systems, which chemically bind powdered metal hydrides to hydrogen at high temperatures.

The discovery could remove the principal stumbling block to hydrogen-powered cars.

The method could be ready for production use within five years, according to the researchers. The work appeared in the May 16, 2003 issue of Science.