report
6.4.5 Applications and perspectives

As mentioned in the chapter before, the lack of knowledge on the efficiency and effectiveness of photocatalytical reactions limit the application currently to disinfection. Systems for water disinfection are already on the market (e.g. tubes coated with nano-TiO2) and should have a significant market potential in developing countries. This application is not yet common, but the use is expected to increase significantly in the next years. Applications for photocatalytic systems are also seen in the treatment of contaminated water for which no effective or only very expensive systems exist today..

The same can be stated for water treatment with metals, metal oxides, BDD and other materials. At the time, there is no need to replace current systems in most cases and therefor the application of nanotechnological materials will be restricted to niche markets or applications where no conventional treatment exists so far.

With nanofiltration the situation is different. Nanofiltration has further fields of application such as removal of hardness and desalination which makes it to be a promising technology especially in combination with other techniques. In addition, there is no risk associated with nanofiltration as no particulate material is involved and because filtration is a physical process (not based on chemical reactions where potentially unknown sideproducts could be produced).

Even though there is extensive research on nanofiltration and great hope is placed on new discoveries (e.g. http://www.technologyreview.com/nanotech/16977/), nanofiltration is not yet ready for largescale application among others due to problems with membrane fouling. But it can be expected that in around 10 years, the applications will be commercially available. On www.freepatentsonline.com already a few applications of nanofiltration membranes are found e.g. for drinking water treatment (http://www.freepatentsonline.com/EP1359124.html) or for water softening (http://www.freepatentsonline.com/5152901.html)

A google-websearch revealed only a few products advertised as nano-enhanced drinking water purification systems. At the University of South Austrailie (UniSA) scientists have developped a purification system which uses silica particles coated with an active nano-material. Its “active” nanomaterial is though not further specified (www.unisa.edu.au/news/2008/110808.asp).

In Siberia nanosorbents are used to remove arsenic from drinking water: http://ricstc.com/en/products/full_text/id.11

At Rice University, a method is being developed which removes arsenic from water with iron oxide nanoparticles. The nanoparticle production should be possible by using only fatty acids (e.g. oil) and rust. The simple production process should allow the application of this method in developing countries and countries in transition (e.g. India and Bangladesh).