New ionic liquid in thermometers beats mercury on range, performance and safety

Mar 26, 2008

Poisonous mercury in thermometers has been replaced by harmless and better performing ionic liquids in research by scientists from Europe and the US, published in the Royal Society of Chemistry journal Green Chemistry.

Ionic liquids (ILs) are salts in liquid form and already have a wide range of applications, from use in drug delivery to fuel cells and batteries. Robin Rogers of Queen's University of Belfast, UK, and his colleagues have now found another role for them. “We have known the basic properties of ILs and have thought for some time that they should make a great thermometer fluid,” says Rogers. “We simply had to prove it!”

ILs offer several advantages for thermometers: they have a faster temperature response time compared with mercury and operate over a wider range of temperatures compared with many molecular liquids, including ethanol.

Non-toxic ILs can be used and their low volatility reduces their ability to escape into the environment, giving an additional environmental advantage over mercury, which needs to be carefully disposed of if a thermometer is broken.

To make its thermometers the US team used normally colourless ionic liquids coloured red with an IL-dye. This made the liquid level easily visible without affecting the linear relationship between liquid volume and temperature. The thermometers could be adapted for a particular temperature range by changing the make-up of the liquid.

Rogers and colleagues chose an ammonium-based liquid for general applications, as it is economical and non-toxic. They also used an alkylphosphonium-based liquid for a more specialised thermometer with a wider temperature range.

Rogers suggests that the thermometers could have uses both in industry and research and development. “Specialty thermometers with a suitable liquid range could be interesting for operation under extreme environment conditions,” he says, “for example, Antarctica and deep sea vents.”

Gary Baker, who also works with ILs, at Oak Ridge National Laboratory, US, says that “using an IL as a filling fluid toward a new class of liquid-in-glass thermometer nicely illustrates the broad potential of ILs as potentially green replacements for conventional solvents.” He adds that “the work opens up yet another avenue in engineering science, as ILs continue to find relevance in increasingly diverse areas.”

Original article: Héctor Rodríguez, Green Chem., 2008, DOI: 10.1039/b800366a

Source: Royal Society of Chemistry

Explore further: Dead feeder cells support stem cell growth

Related Stories

Apple wins patent appeal in China

52 minutes ago

Apple has won an appeal in China over patent rights to voice recognition software such as the iPhone's "Siri", with a court overruling an earlier decision that had gone against the US technology giant.

Google search mobile switch a revolution for some

1 hour ago

Google's latest Internet revolution this week saw the web giant modify its search algorithm to favour mobile-friendly sites, in a bid to upstage Apple that US media branded a "mobilegeddon".

Apple Watch goes on sale—quietly—in Asia

1 hour ago

The Apple Watch debuted in some Asian markets Friday, but with sales limited to those who had pre-ordered online it was a low-key start with none of the fanfare and fuss usually seen for a launch by the tech ...

Recommended for you

Dead feeder cells support stem cell growth

Apr 24, 2015

Stem cells naturally cling to feeder cells as they grow in petri dishes. Scientists have thought for years that this attachment occurs because feeder cells serve as a support system, providing stems cells ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.