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Liquid carbon dioxideis the liquid state ofcarbon dioxide(CO
2), which cannot occur under atmospheric pressure. It can only exist at a pressure above 5.1 atm (5.2 bar; 75 psi), under 31.1 °C (88.0 °F) (temperature ofcritical point) and above −56.6 °C (−69.9 °F) (temperature oftriple point).[1]Low-temperature carbon dioxide is commercially used in its solid form, commonly known as "dry ice".SolidCO
2sublimesat 194.65 K (−78.5 °C; −109.3 °F) at Earthatmospheric pressure— that is, it transitions directly from solid to gas without an intermediate liquid stage. The uses and applications of liquid carbon dioxide include decaffeinating coffee,[2]extracting virgin olive oil from olive paste, in fire extinguishers, and as a coolant.
Properties
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Liquid carbon dioxide is a type of liquid which is formed from highly compressed and cooled gaseous carbon dioxide. It does not form under atmospheric conditions. It only exists when the pressure is above 5.1 atm and the temperature is under 31.1 °C (88.0 °F) (temperature ofcritical point) and above −56.6 °C (−69.9 °F) (temperature oftriple point). The chemical symbol remains the same as gaseous carbon dioxide (CO
2).[3]It is transparent and odorless and the density of it is 1101 kg/m3when the liquid is at full saturation at −37 °C (−35 °F).[4]
Thesolubilityof water in liquid carbon dioxide is measured in a range of temperatures, ranging from −29 °C (−20 °F) to 22.6 °C (72.7 °F). At this temperature, the pressure is measured in a range from 15 to 60 atmospheres. The solubility turned out to be very low: from 0.02 to 0.10 %.[5]
Uses
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Uses of liquid carbon dioxide include the preservation of food, in fire extinguishers, and in commercial food processes. Forfood preservation,liquid carbon dioxide is used to refrigerate, preserve, store and soften. In a fire extinguisher, theCO
2is stored under pressure as a liquid to act as an anti-flammable.[3]The liquid carbon dioxide not only reduces combustion by displacingoxygen,but also cools the burning surface to avoid further damage.Solvent extractionusing compressed liquidCO
2can be used in industrial processes such as removingcaffeinefromcoffee[3]or improving the yield ofolive oilproduction.[6]
Liquid carbon dioxide is being considered as a means of CO2transportation for underground or subsea storage purposes. Due to its high density as a liquid, it is much more feasible to ship than as a gas.[citation needed]
CO
2is also used in large-scale air-to-water heat pumps for district heating, replacing less environmentally friendly refrigerants. TheCO
2changes phases between liquid and gaseous in the process.[7]
See also
editOther chemical compounds and elements are commonly used for commercial and research purposes in their liquid state:
References
edit- ^"How to Make Liquid CO2".Sciencing.Retrieved2019-06-11.
- ^Zabot, Giovani L. (January 2020)."Chapter 11 - Decaffeination using supercritical carbon dioxide".Green Sustainable Process for Chemical and Environmental Engineering and Science.Elsevier. pp.255–278.doi:10.1016/B978-0-12-817388-6.00011-8.ISBN9780128173886.S2CID209725830.Retrieved2022-01-01.
{{cite book}}:|website=ignored (help) - ^abc"What is Liquid CO2 and What Can It Be Useful For? | Co2 Gas Blog".Co2 Gas Company.2017-10-08. Archived fromthe originalon 2019-04-09.Retrieved2019-04-30.
- ^"Carbon Dioxide - Thermophysical Properties".engineeringtoolbox.2017.
- ^Stone, Hosmer W. (December 1943). "Solubility of Water in Liquid Carbon Dioxide".Industrial & Engineering Chemistry.35(12):1284–1286.doi:10.1021/ie50408a015.ISSN0019-7866.
- ^Romano, Raffaele; Manzo, Nadia; Montefusco, Immacolata; Romano, Annalisa; Santini, Antonello (2014-03-12)."Liquid Carbon Dioxide Use in the Extraction of Extra Virgin Olive Oil From Olive Paste".Journal of Food Research.3(4): 119.doi:10.5539/jfr.v3n4p119.ISSN1927-0895.
- ^"MAN Energy Solutions to Supply World's Largest Air-to-Water Heat Pump for Helsinki's District Heating".28 August 2024.Retrieved28 August2024.