Talk:Supercritical fluid

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This section is rubbish. It confuses two very different natural phenomena - volcanoes and hydrothermal circulation, which can be closely related but are not the same thing at all. I'm going to attempt to completely re-write this.

139.166.247.131 (talk) 15:24, 6 February 2014 (UTC)[reply]

What's with the graph? Cleanup this articles, requires. Wobblies 21:40, 14 June 2007 (UTC)[reply]

The articles on this subject are a bit haphazard, with some duplicate articles (critical point drying and supercritical drying are synonomous, yet each has an article), and much duplicated information in different articles. For example, there is supercritical fluid, supercritical carbon dioxide, critical temperature and critical point, all of which essentially begin by describing the same thing. I am considering major editing on these topics to create a more logical structure, linking to eachother in a more logical way. I would start with this article, and use it as a "hub" to get to the others. This would involve cleaning up and editing to clarify the descriptions of the graphs, adding some more sub headings, particularly under "applications", with a brief discription. I would link these brief descriptions to existing articles in most cases, where there is one, and create a new one where there was not, to be added later. Some articles could be replaced with a link to this article (e.g. supercritical carbon dioxide, critical point, critical temperature) and a new link created for critical pressure. (The critical point article is particularly unclear, as it contains different meanings of critical point in the same article, requiring disambiguation?) I am fairly new to this, and don't want to step on toes, is this the right way to go about it? Stainless316 12:01, 16 November 2007 (UTC)[reply]

I have changed the article in line with my previous comment. I have tried to keep the information as it was previously, and included all the applications, added a new article under "supercritical fluid extraction". Work is ongoing, any comments welcome.Stainless316 (talk) 11:02, 7 January 2008 (UTC)[reply]

I have added tag suggesting merging supercritical CO2 into this article. In fact i have already added most of the content from there into this article, so all it needs is re-directing. —Preceding unsigned comment added by Stainless316 (talk • contribs) 20:10, 11 December 2008 (UTC)[reply]

• Is there any supercritical fluid at pressure?--MathFacts (talk) 15:01, 23 July 2009 (UTC)[reply]
• The "therefore" in the part which describes the property of ${\displaystyle N_{2}}$ in the high-pressured tank does not make sense. The logic ought to be like :a) nitrogen (or compressed air) in a gas cylinder above this pressure is actually a supercritical fluid and b)nitrogen in a gas cylinder behave like a kind of ordinary gas --> they are called "permanent gases".

Am I confused or is the diagram mislabeled? In both the "supercritical fluid" and "supercritical carbon dioxide" articles, the diagram has a vertical axis in P(bars), and shows the critical point of CO2 at about 7 bars. The text in both places gives the critical pressure as 7.38 MPa, aka 73.8 bars. I'm not confident enough in this area to go altering the diagram (which in any case would require me to learn how to edit SVG), but it certainly looks to me like the diagram is wrong. I'd love an explanation one way or the other. Paleolith (talk) 17:31, 12 March 2012 (UTC)[reply]

I think you're confusing the triple point and the critical point. The critical point in the diagram is indeed at about 73 bar.Kermitchemist (talk) 13:09, 30 August 2020 (UTC)[reply]

The section titled Carbon capture and storage and enhanced oil recovery contains the following sentence:

'....The CO2 is separated from other flue gases either pre- or post-combustion.....'

Separating CO2 from other flue gases pre- combustion does not make sense, for two reasons. First, flue gas describes the gas created by combustion, so there is no pre- combustion flue gas. Second, CO2 is present only in minute quantities prior to combustion, so it isn't really available to be separated pre- combustion. — Preceding unsigned comment added by 24.250.167.105 (talk) 17:42, 23 September 2012 (UTC)[reply]

I feel something strange in the style of the text while reading the second paragraph of this section. And there is a duplicate reference in it as well. Maybe someone else smells the fish? 82.31.160.48 (talk) 00:51, 8 August 2014 (UTC) Let me stress it again - I feel that Mr. Bolmatov might be trying to use Wikipedia to promote himself a bit.131.227.125.163 (talk) 13:12, 16 January 2015 (UTC)[reply]

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This section describes temperatures being far above the critical point but then goes on to describe a smooth transition to liquid. There should be no liquid above the critical temperature. 2600:387:2:805:0:0:0:86 (talk) 03:07, 28 November 2016 (UTC) BGriffin[reply]

This usage does not match my understanding of the meaning of "effuse". Should it be "expand into empty space like a gas", or "diffuse through solids"(sounds wrong - depends on the solid, and is not at all a unique property of gases), or something else? Latrissium (talk) 21:23, 17 November 2017 (UTC)[reply]

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The French version now has an improved p-T phase diagram in which the dotted lines between supercritical and liquid phases, and between supercritical and gas phases, have been replaced by a gradual color change as shown here. This is a better representation of the physical reality, since there is no abrupt physical transition when heating liquid to supercritical or when compressing gas to supercritical. The new diagram was drawn by Sémhur (see the French talk page), and I think it should be used on this page too. But first we need an English version in which the words on the diagram are translated in the svg file. Does someone know how to edit the svg file? Dirac66 (talk) 22:14, 12 November 2018 (UTC)[reply]

Take a look at File:Carbon_dioxide_pressure-temperature_phase_diagram-en.svg? --Rifleman 82 (talk) 00:59, 13 November 2018 (UTC)[reply]

Not necessarily. See for example https://pubs.acs.org/doi/abs/10.1021/ed049p249 I am not sure how to correct this mistake, what should be edited in place of it. [Edit 27 July 2019 by 181.177.33.91]

The complete sentence near the end of the Properties section is "All supercritical fluids are completely miscible with each other so for a mixture a single phase can be guaranteed if the critical point of the mixture is exceeded."

Perhaps it could be "Most supercritical fluids are completely miscible with each other, so for a mixture a single phase is obtained if the critical point of the mixture is exceeded. However exceptions do exist such as ..." (citing your reference).Dirac66 (talk) 23:25, 29 July 2019 (UTC)[reply]

OK, I have now read this reference and inserted a paragraph about immiscible supercritical systems into the article. Thanks for pointing out the reference. Dirac66 (talk) 02:08, 2 August 2019 (UTC)[reply]

Some myths have crept into this article. I've deleted the following two myths:

• “The fluid will also be called supercritical even if its temperature is below critical point value. In that case, it will be a highly compressed liquid. But pressure is mandatory to be above the critical value.” (This isn't true. A fluid at a temperature below the critical temperature is called "subcritical", not "supercritical".)

• The statement that Cagniard de la Tour used a cannon barrel. (That's a myth caused by a mis-translation of the original French. In his report, he said he used "un bout de canon de fusillade très epais." That translates to "the end of a thick-walled gun barrel". The French word "canon" means "gun", not necessarily the English word "cannon". Considering that he later picked up the gun and shook it beside his ear, it's very unlikely that it was a cannon. More likely a musket or some other small gun.)Kermitchemist (talk) 13:09, 30 August 2020 (UTC)[reply]

In the reactions section, I added some more content about industrial reactions in SCFs and deleted the following sentence "An electrochemical carboxylation of a para-isobutylbenzyl chloride to Ibuprofen is promoted under supercritical carbon dioxide." That sentence mentioned a very specific reaction that is far from being the most important example of a reaction in a supercritical fluid. This section on reactions deserves more content, which I may add in the future, but the example reactions should, in my opinion, be more scientifically significant than that single example and should be given context such as their importance to scientific discovery or in relation to specific advantageous properties of SCFs, rather than merely being a listing of random examples.Kermitchemist (talk) 17:55, 31 August 2020 (UTC)[reply]