Clearing the air with nanoparticles

According to US researchers nanoparticles could be pumped into a burning building to clear poisonous smoke.

A team at Kansas State University is searching for the most effective nanoparticle to clear smoke from fires and to improve visibility on the battleground for the military. In tests one particular particle cleared military smoke 15 times faster than leaving it to dissipate naturally.

Prof Ronaldo Maghirang, project leader on smoke reduction research at Kansas State University, said the nanoparticles cling to the smoke particles, causing them to plummet to the ground.

‘It appears that a higher surface area, relatively large aggregate size and a reactivity with the smoke particles make them more effective than other smoke-clearance methods like charged water droplets,’ he said.

The team compared a range of commercially available particles, including sodium bicarbonate used in fire extinguishers and calcium hydroxide, which was effective but proved toxic.

The researchers said magnesium oxide particles have shown the best performance so far. Another group is working in parallel to determine whether the nanoparticles could pose a later health risk if dispersed into the environment. However, preliminary results showed that the magnesium oxide particles were not toxic, said Maghirang.

The team plans to expand testing in the next few months into combustion smoke clearance. ‘That is the biggest application we’re shooting for,’ said Maghirang. ‘The good thing about the nanoparticles is that they will remove the toxic components of the combustion smoke. Water droplets can do that too, but because nanoparticles have a larger surface area they react more with those dangerous components.’

Next year the team will also examine the potential of nanoparticles in fire suppression.

The researchers are examining the method of pumping nanoparticles into a space to increase performance.

‘If some of the particles can be charged electrostatically it should improve their interaction with the smoke particles,’ said Maghirang.

‘By using an appropriate nozzle we should be able to manipulate the charge.’