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Poisonous mercury in thermometers has been replaced by harmless and better performing ionic liquids in research by scientists from Europe and the US, published in the Royal Society of Chemistry journal Green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: Team pioneers strategy for creating new materials

add to favorites email to friend print save as pdf

Related Stories

Animals first flex their muscles

1 hour ago

An unusual new fossil discovery of one of the earliest animals on earth may also provide the oldest evidence of muscle tissue – the bundles of cells that make movement in animals possible.

Introducing the multi-tasking nanoparticle

4 hours ago

Kit Lam and colleagues from UC Davis and other institutions have created dynamic nanoparticles (NPs) that could provide an arsenal of applications to diagnose and treat cancer. Built on an easy-to-make polymer, these particles ...

Eta Carinae: Our Neighboring Superstars

4 hours ago

(Phys.org) —The Eta Carinae star system does not lack for superlatives. Not only does it contain one of the biggest and brightest stars in our galaxy, weighing at least 90 times the mass of the Sun, it ...

Recommended for you

Team pioneers strategy for creating new materials

Aug 29, 2014

Making something new is never easy. Scientists constantly theorize about new materials, but when the material is manufactured it doesn't always work as expected. To create a new strategy for designing materials, ...

Plug n' Play protein crystals

Aug 29, 2014

Almost a hundred years ago in 1929 Linus Pauling presented the famous Pauling's Rules to describe the principles governing the structure of complex ionic crystals. These rules essentially describe how the ...

Protein glue shows potential for use with biomaterials

Aug 28, 2014

Researchers at the University of Milan in Italy have shown that a synthetic protein called AGMA1 has the potential to promote the adhesion of brain cells in a laboratory setting. This could prove helpful ...

User comments : 0