Nanotechnology approaches to water purification
Researchers – Alpana Mahapatra, Farida Valli and Karishma Tijoriwala from the D.J. Sanghvi College of Engineering, in Mumbai, India, explain that there are several nanotechnology approaches to water purification currently being investigated and some already in use.
In most of the nanotechnology approaches to water purification the materials used are carbon nanotubes and alumina fibers for nanofiltration, nanoscopic pores in zeolite filtration membranes, nanocatalysts and magnetic nanoparticles. Nanosensors, such as those based on titanium oxide nanowires or palladium nanoparticles are used for analytical detection of contaminants in water samples.
The research team claims that nanotechnology can purify water of sediments, chemical effluents, charged particles, bacteria and other pathogens. These researchers say that nanotechnology can also purify water of toxic trace elements such as arsenic, and viscous liquid impurities such as oil.
According to the researchers the main advantages of using nanofilters, as opposed to conventional systems, are that less pressure is required to pass water across the filter, they are more efficient, and they have incredibly large surface areas and can be more easily cleaned by back-flushing compared with conventional methods. For instance, carbon nanotube membranes can remove almost all kinds of water contaminants including turbidity, oil, bacteria, viruses and organic contaminants. Although their pores are significantly smaller, carbon nanotubes have shown to have an equal or a faster flow rate as compared to larger pores, possibly because of the smooth interior of the nanotubes. Nanofibrous alumina filters and other nanofiber materials also remove negatively charged contaminants such as viruses, bacteria, and organic and inorganic colloids at a faster rate than conventional filters.
A caution
But the researchers caution that even though water purification based on nanotechnology has not yet led to any human health or environmental problems, further research into the biological interactions of nanoparticles should be carried out. This is because in nanomaterials such as carbon nanotubes the much greater surface area to volume ratio of nanoparticles can make them more reactive and lead to so far unrecognized and untested interactions with biological surfaces.
Source: http://www.inderscience.com/search/index.php?action=record&rec_id=33766&prevQuery=&ps=10&m=or
July 28, 2010