Water Pollution and Nanotechnology

How can nanotechnology be used to reduce water pollution?

Nanotechnology is being used to develop solutions to three very different problems in water quality.

One challenge is the removal of industrial water pollution, such as a cleaning solvent called TCE, from ground water. Nanoparticles can be used to convert the contaminating chemical through a chemical reaction to make it harmless. Studies have shown that this method can be used successfully to reach contaminates dispersed in underground ponds and at much lower cost than methods which require pumping the water out of the ground for treatment.

Another challenge is the removal of salt or metals from water. A deionization method using electrodes composed of nano-sized fibers shows promise for reducing the cost and energy requirements of turning salt water into drinking water.

The third problem concerns the fact that standard filters do not work on virus cells. A filter only a few nanometers in diameter is currently being developed that should be capable of removing virus cells from water.

See the following section for more about the potential of nanotechnology in removing contaminates from water.

Water Pollution: Nanotechnology Applications under Development

Using nanoscavengers, in which a layer of reactive nanoparticles coat a synthetic core which is designed to be easily magnetized. The nanoparticles, for example silver nanoparticles if bacteria is a problem, attach to or kill the pollutants. Then when a magnetic field is applied the nanoscavengers are removed from the water.

Using pellets containing nanostructured palladium and gold as a catalyst to breakdown chlorinated compounds contaminating groundwater. Since palladium is very expensive the researchers formed the pellets of nanoparticles that allow almost every atom of palladium to react with the chlorinated compounds, reducing the cost of the treatment.

Using enzyme-functionalized micromotors to remove carbon dioxide from water.

Researchers at the University of Cincinnati have demonstrated a method of removing antibiotics contaminating waterways. The method uses vesicle nanoparticles that absorb antibiotics.

Using graphene oxide to remove radioactive material from water. Researchers found that flakes of graphene oxide absorbs radioactive ions in water. The graphene oxide then forms clumps that can be removed from the water for disposal.

Using graphene as a membrane for low cost water desalination. Researchers have determined that graphene with holes the size of a nanometer or less can be used to remove ions from water. They believe this can be used to desalinate sea water at a lower cost than the reverse osmosis techniques currently in use.

Using carbon nanotubes as the pores in reverse osmosis membranes. This can decrease the power needed to run reverse osmosis desalination plants because water molecules pass through carbon nanotubes more easily than through other types of pores. Other researchers are using carbon nanotubes to develope small, inexpensive water purification devices needed in developing countries.

Also carbon nanotubes are being developed to clean up oil spills. Researchers have found that adding boron atoms during the growth of carbon nanotubes causes the nanotubes to grow in a sponge like material that can absorb many times it's weight in oil.

Using hair like nanoparticles (nano-hair) to trap and measure the level of mercury pollution in water.

Combining a nanomembrane with solar power to reduce the cost of desalinating seawater

Using iron nanoparticles to clean up carbon tetrachloride pollution in ground water

Adding graphene oxide to sand filters to enhance their ability to remove pollutants from water.

Using silver chloride nanowires as a photocatalysis to decompose organic molecules in polluted water.

Using an electrified filter composed of silver nanowires, carbon nanotubes and cotton to kill bacteria in water.

Nanoparticles that can absorb radioactive particles polluting ground-water

Coating iron nanoparticles allow them to neutralize dense, hydrophobic solvents polluting ground-water

Using nanowire mats to absorb oil spills

Using iron oxide nanoparticles to clean arsenic from water wells.

Using gold tipped carbon nanotubes to trap oil drops polluting water.

Using antimicrobial nanofibers and activated carbon in a disposable filter as an inexpensive way to clean contaminated water.

Researchers at Pacific Northwestern Laboratory have developed a material to remove mercury from groundwater. The material is called SAMMS, which is short for Self-Assembled Monolayers on Mesoporous Supports. This translates taking a ceramic particle whose surface has many nano-size pores and lining the nanopores with molecules that have sulfur atoms on one end, leaving a hole in the center that is lined with sulfur atoms as shown in figure-SAMMS. They line the nanopores with molecules containing sulfur because it bonds to mercury, so mercury atoms bond to the sulfur and are trapped in the nanopores.

Water Pollution: Nanotechnology Company Directory

Company Product
SiREM Iron nanoparticles to treat groundwater pollutants
Campbell Applied Physics Also working on Capacitive Deionization using carbon aerogel
NanoH2O Nanotechnology enhanced membranes for water desalination
More nanotechnology companies working on water pollution

Other Environmental Related Pages

Compiled by Earl Boysen of Hawk's Perch Technical Writing, LLC and UnderstandingNano.com. You can find him on Google+.

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