Keeping Desalination Plants Clean

19th January 2007

As much as a third of the cost of water desalination is made up of maintenance costs. So a fair amount of thought has to be put into making surfaces that come in contact with air & water clean. I have mentioned in a previous post called The Pipeline that there is a product called Sharkote-– a US navy funded coating announced in 2005 that immitates the skin of a shark. Sharkote might be used inside the pipes that carry water. (barnicles & algae don’t grow on shark skin like they do on whale skin so Sharkote would also serve well to reduce maintenance in algae farms)

Recently, a number of other possible kinds of surface applications have come out of the labs. This first application looks like its more suitable for places inside desalination plants– surfaces that are damp but not directly connected to fresh water production.

Spiky surface ‘kills infections’

The coating inactivated the influenza virus

Adding a special “spiky” coating to surfaces can kill bacteria and viruses, research suggests. US scientists found painting on spike-like structures kept the surfaces infection-free.

The spikes, they believe, rupture bacteria and virus particles on contact, inactivating them.

The team, writing in the Proceedings of the National Academy of Sciences, suggest their findings could help to fight the spread of diseases.

Given the simplicity of the coating procedure, it should be applicable to various common materials

Massachusetts Institute of Technology

The researchers painted glass with long chains of molecules, called polymers, which anchored to the surface to form tentacle-like spikes.

When the team then applied the surfaces with E. coli and Staphylococcus aureus (both common disease-causing forms of bacteria) and the influenza virus, they found the coating killed them with 100% efficiency within minutes.

Click here for the rest of the article.

This next product might be used for outside surfaces of desalination plants that face the sun– or green houses used for biodiesel and desalination production.)

Eco glass cleans itself with Sun

By Jo Twist
BBC News Online science and technology staff

Normal glass (left) and Activ (right) makes for clear views

A revolutionary kind of glass that needs little cleaning could mean soap and chamois are banned for good. The Pilkington Activ glass has a special nano-scale – extremely thin – coating of microcrystalline titanium oxide which reacts to daylight.

This reaction breaks down filth on the glass, with no need for detergent. When water hits it, a hydrophilic effect is created, so water and dirt slide off.

It is one of four finalists for the eminent MacRobert engineering award.

The prize is given out by the UK’s Royal Academy of Engineering for technological and engineering innovation.

‘Nano’ cleaning

“Pilkington Activ is based on titanium dioxide, which is used in foodstuffs, toothpastes, and sun cream,” explained Dr Kevin Sanderson, one of the team members who developed Activ at Pilkington’s technical research centre.

“But usually it is a white powder which is not ideal for glass because you can’t see though it.

Each time harsh chemicals are used, they are washed off into ground, which produces contamination. What we say here is that you can just spray water on top

Dr Kevin Sanderson, Pilkington

“So we used it in a thin film form – 15 nanometres thick – so that it appears as close to normal glass as it can.”

Although not strictly nanotechnology, the special coating and the chemical reactions happen at the nano-scale (one thousand millionth of a metre).

The titanium dioxide coating on the glass had two properties that made it special, said Dr Sanderson.

Click here to see how the glass works

Click here to read the rest of the article.

This last coating is like the coating that is activated by the sun. However, it works in wavelengths that would be suitable for light bulbs. So it would prevent the growth of fungus and the build up of dirt on the damp inner surfaces of a desalination plant.

Self-cleaning bathroom on the way

By Marina Murphy

Few of us enjoy the weekly blitz on the bathroom

Nanotechnology may yet rescue us from the drudgery of the weekly ritual of blitzing the bathroom.

Scientists in Australia have developed an environmentally friendly coating containing special nanoparticles that could do the job of cleaning and disinfecting for us.

“If you have self-cleaning materials, you can do the job properly without having to use disinfectants and other chemicals,” says researcher Rose Amal at the Particles and Catalysts Research Group, University of New South Wales, where the coating is being developed.

Previously self-cleaning materials were limited to outdoor applications because ultraviolet light was required to activate the molecules in the coatings.

Less time cleaning the bathroom is rather appealing

Mary Taylor, Friends of the Earth

These surfaces contain tiny particles of titanium dioxide, which become excited when they absorb ultraviolet light with a wavelength of less than 380 nanometres.

Light activated

This gives the particles an oxidizing ability stronger than chlorine bleach. The excited particles can break down organic compounds and kill bacteria.

The new coating contains modified particles of titanium dioxide, which are doped with other cations like iron or vanadium and anions like oxygen, nitrogen or carbon.

This coating can absorb light at the higher wavelengths in visible light, such as the bathroom light.

The coating can kill bacteria such as E. coli

Lab experiments revealed the surface of coated glass could kill the bacteria E. coli (Escherichia coli) and degrade volatile organic compounds in visible light.

The oxidising properties also mean fungus cannot grow on the surface. And because the coating is hydrophobic – it does not like water – the water simply slides away carrying any dirt with it, rather than gathering as droplets.

Using the coating in baths and sinks would not pose any problems with skin irritation, according to Amal.

“When the bath is filled, the water would attenuate the light so I don’t think the surface would activate. It will only be active if the light can reach the surface,” she says.

For the rest of the article click here.