Nanotechnology for purification: nanowater
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Nanofiltration of oil into diesel
Silicium nanofilter
Lifesaver bottle
Functionalised nanopores
Nanoporous iron particles |
Water-treatment plants have been using nanofiltration and ultrafiltration membranes to separate good water from bad for many years now, but the technology and the use of nanomaterials is still increasing. Nanotechnology water treatment devices Given the importance of clean water to people in developed and developing countries, numerous organizations are considering the potential application of nanoscience to solve technical challenges associated with the removal of water contaminants. Technology developers and others claim that these technologies offer more effective, efficient, durable, and affordable approaches to removing specific types of pollutants from water. A range of water treatment devices that incorporate nanotechnology are already on the market and others are in advanced stages of development. These nanotechnology applications include:
Lifesaver bottle The lifesaver bottle (UK) contains a membrane sytem with 15 nm pores preventing bacteria and viruses to pass. In combination with a standard dirt filter, active carbon and a hand-operated pump it can be used to transform any (sweet) water into drinking water. See attached video. Nanofiltration and desalination Nanofiltration membrane technology is already widely applied for removal of dissolved salts from salty water, removal of micro pollutants, water softening, and wastewater treatment. Nanofiltration membranes selectively reject substances, which enables the removal of harmful pollutants and retention of nutrients present in water that are required for the normal functioning of the body. It is expected that nanotechnology will contribute to improvements in membrane technology that will drive down the costs of desalination, which is currently a significant impediment to wider adoption of desalination technology. Source materials for nanofilters include naturally occurring zeolites and attapulgite clays, which can now be manipulated on the nanoscale to allow for greater control over pore size of filter membranes. Researchers are also developing new classes of nanoporous polymeric materials that are more effective than conventional polymer filters. Nanocatalysts and magnetic manoparticles Researchers expect that nanocatalysts and magnetic nanoparticles will enable the use of heavily polluted water for drinking, sanitation, and irrigation. Using catalytic particles could chemically degrade pollutants instead of simply moving them somewhere else, including pollutants for which existing technologies are inefficient or cost prohibitive. Magnetic nanoparticles, when coated with different compounds that have a selective affinity for diverse contaminating substances, could be used to remove pollutants, including arsenic, from water. Companies are commercializing these technologies and researchers are frequently publishing new discoveries in this area. Nanotube filters An exciting development is the membrane filter made from 100% CNT (carbon nanotubes): here the carbon nanotube itself is used to filter the water. Because of the small internal diameter, only water is transported through the tube and other components such as bacteria, viruses, heavy metals, human acids, endotoxins and middle and large sized molecules are excluded. Surprisingly, the pressure drop is very little and the water flux very high. The advantages are:
Capacitive deionisation with carbon aerogels Carbon aerogel is a unique material with a very high specific surface area, upto 4000 m2/gram, that lend itself to some extremely useful applications for capacitors (see nano battery) but also for water purification. For instance, when a voltage is applied across two adjacent sheets of carbon aerogel submerged in water:
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