Argon vs Nitrogen for Glove Boxes
Argon and nitrogen are both unreactive gases that you can use to create an inert environment within your glove box. Both gases will efficiently displace air within a confined space, are easy to store, and will not react with most materials. Therefore, both N2 and Ar can create a glove box environment with very low moisture and oxygen levels. However, there are some distinguishing qualities that might make a nitrogen or argon source the right choice for your inert environment.
- Inert Atmosphere
- Low Ingression Materials
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A major factor to consider when choosing between a nitrogen or an argon supply for your glove box gas is cost. Creating and sustaining a glove box takes a substantial amount of gas, and therefore even small difference in price per L (or m3) can make a big difference in the running costs for your glove box.
The graph above shows the relative prices of argon and nitrogen compared to the same volume of compressed air. Here, we can see that regardless of volume supplied, it costs roughly the same for a cylinder of compressed air as it does for a cylinder of N2. However, compressed argon is nearly three times the price of both air and nitrogen. Argon only takes up 0.9% of the atmosphere, while nitrogen makes up ~78%, making it the most abundant gas on earth. The low abundance of argon makes it much more difficult to extract from the air than nitrogen, which therefore increases its expense significantly. It will cost you three times as much to run your glove box on argon as it will on nitrogen. However, for most experiments, nitrogen will achieve the same inertness levels as argon.
The nitrogen atom is not inert, as it only has five electrons in its outer orbital. Instead, in its diatomic form, N2, it is an unreactive gas. This means that many materials do not react with it, but there are a few that do. Generally, nitrogen reactions are more likely to occur at high temperatures. An example of this is the reaction between nitrogen and lithium, which leads to the production of nitrides such as lithium nitrides.
Argon, however, is completely inert, and it is exceedingly rare that it will react with anything under atmospheric conditions. As a result, if you are using materials that will react with nitrogen in your glove box, it would be a better choice to use argon as your filler gas. An example of this would be if you were working in lithium battery research.
Argon is a denser material than both nitrogen and air. Because of it's increased density, argon is more effective at displacing air within a confined space. Arguably, this means that you may need to purge your glove box for less time to achieve an inert environment.
Essentially, argon is likely to “blanket” or act as a protective barrier over the reaction in your glove box. This helps to protect it from any contaminants, and it means that oxygen and water vapour will be less likely to mix with argon than with nitrogen. In theory, air is less likely to creep into an argon-filled system, while argon is less likely to escape a glove box than nitrogen. However, as most manufacturers aim to make glove boxes as leak-proof as possible, this shouldn’t make a massive difference.
On the other hand, if you do need extremely low levels of moisture and oxygen for your glove box environment, then argon may be the right choice for you.
Argon or Nitrogen?
Generally, you can create a very inert environment by using either argon or nitrogen. However, using nitrogen is likely to be a third of the cost of argon. Therefore, for most cases, we recommend that you keep costs down and use nitrogen to maintain your inert glove box environment.
Having said this, your choice of material will be entirely dependent on your samples and your experiment. Examine your reactions and read the papers associated with your field to help you decide. This will give you an insight into whether it is necessary to use an argon-based environment for your glove box.
- Bench Top
- Automated Purging
- Inert Environment
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