Carbonation

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Carbonation is the chemical reaction of carbon dioxide to give carbonates, bicarbonates, and carbonic acid. [1] In chemistry, the term is sometimes used in place of carboxylation, which refers to the formation of carboxylic acids.

Contents

In inorganic chemistry and geology, carbonation is common. Metal hydroxides (MOH) and metal oxides (M'O) react with CO2 to give bicarbonates and carbonates:

MOH + CO2 → M(HCO3)
M'O + CO2 → M'CO3

Selected carbonations

Carbonic anhydrase

In mamalian physiology, transport of carbon dioxide to the lungs involves a carbonation reaction catalyzed by the enzyme carbonic anhydrase. In the absence of such catalysts, carbon dioxide cannot be expelled sufficient rate to support metabolic needs. The enzyme harbors a zinc aquo complex, which captures carbon dioxide to give a zinc bicarbonate: [2]

[(imidazole)3ZnOH]+ + CO2[(imidazole)3ZnOCO2H]+

Behavior of concrete

In reinforced concrete, the chemical reaction between carbon dioxide In the air and calcium hydroxide and hydrated calcium silicate in the concrete is known as neutralisation. The similar reaction in which calcium hydroxide from cement reacts with carbon dioxide and forms insoluble calcium carbonate is carbonatation.

Urea production

Carbonation of ammonia is one step in the industrial production of urea:In 2020, worldwide production capacity was approximately 180 million tonnes. [3] As a fertilizer, it is a source of nitrogen for plants. Urea production plants are almost always located adjacent to the site where the ammonia is manufactured. [4]

2 NH3 + CO2[NH4]+[NH2COO]

In the subsequent urea conversion: the ammonium carbamate is decomposed into urea, releasing water:

[NH4]+[NH2COO] ⇌ CO(NH2)2 + H2O

Solubility

Henry's law states that PCO2=KBxCO2 where PCO2 is the partial pressure of CO2 gas above the solution. KB is Henry's law constant. KB increases as temperature increases. xCO2 is the mole fraction of CO2 gas in the solution. According to Henry's law carbonation increases in a solution as temperature decreases. [5]

Since carbonation is the process of giving compounds like carbonic acid (liq) from CO2 (gas) {i.e. making liquid from gasses} thus the partial pressure of CO2 has to decrease or the mole fraction of CO2 in solution has to increase {PCO2/xCO2 = KB} and both these two conditions support increase in carbonation.

Related Research Articles

<span class="mw-page-title-main">Bicarbonate</span> Polyatomic anion

In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula HCO
3
.

<span class="mw-page-title-main">Carbonate</span> Salt of carbonic acid

A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula CO2−3. The word carbonate may also refer to a carbonate ester, an organic compound containing the carbonate groupO=C(−O−)2.

Urea, also called carbamide, is an organic compound with chemical formula CO(NH2)2. This amide has two amino groups joined by a carbonyl functional group. It is thus the simplest amide of carbamic acid.

<span class="mw-page-title-main">Calcium carbonate</span> Chemical compound

Calcium carbonate is a chemical compound with the chemical formula CaCO3. It is a common substance found in rocks as the minerals calcite and aragonite, most notably in chalk and limestone, eggshells, gastropod shells, shellfish skeletons and pearls. Materials containing much calcium carbonate or resembling it are described as calcareous. Calcium carbonate is the active ingredient in agricultural lime and is produced when calcium ions in hard water react with carbonate ions to form limescale. It has medical use as a calcium supplement or as an antacid, but excessive consumption can be hazardous and cause hypercalcemia and digestive issues.

Carbonic acid is a chemical compound with the chemical formula H2CO3. The molecule rapidly converts to water and carbon dioxide in the presence of water. However, in the absence of water, it is quite stable at room temperature. The interconversion of carbon dioxide and carbonic acid is related to the breathing cycle of animals and the acidification of natural waters.

<span class="mw-page-title-main">Sodium bicarbonate</span> Chemical compound

Sodium bicarbonate (IUPAC name: sodium hydrogencarbonate), commonly known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO3. It is a salt composed of a sodium cation (Na+) and a bicarbonate anion (HCO3). Sodium bicarbonate is a white solid that is crystalline, but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda (sodium carbonate). The natural mineral form is nahcolite. It is a component of the mineral natron and is found dissolved in many mineral springs.

<span class="mw-page-title-main">Sodium carbonate</span> Chemical compound

Sodium carbonate is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield alkaline solutions in water. Historically, it was extracted from the ashes of plants grown in sodium-rich soils, and because the ashes of these sodium-rich plants were noticeably different from ashes of wood, sodium carbonate became known as "soda ash". It is produced in large quantities from sodium chloride and limestone by the Solvay process, as well as by carbonating sodium hydroxide which is made using the Chlor-alkali process.

<span class="mw-page-title-main">Ammonium bicarbonate</span> Chemical compound

Ammonium bicarbonate is an inorganic compound with formula (NH4)HCO3. The compound has many names, reflecting its long history. Chemically speaking, it is the bicarbonate salt of the ammonium ion. It is a colourless solid that degrades readily to carbon dioxide, water and ammonia.

<span class="mw-page-title-main">Neutralization (chemistry)</span> Chemical reaction in which an acid and a base react quantitatively

In chemistry, neutralization or neutralisation is a chemical reaction in which acid and a base react with an equivalent quantity of each other. In a reaction in water, neutralization results in there being no excess of hydrogen or hydroxide ions present in the solution. The pH of the neutralized solution depends on the acid strength of the reactants.

The Solvay process or ammonia-soda process is the major industrial process for the production of sodium carbonate (soda ash, Na2CO3). The ammonia-soda process was developed into its modern form by the Belgian chemist Ernest Solvay during the 1860s. The ingredients for this are readily available and inexpensive: salt brine (from inland sources or from the sea) and limestone (from quarries). The worldwide production of soda ash in 2005 was estimated at 42 million tonnes, which is more than six kilograms (13 lb) per year for each person on Earth. Solvay-based chemical plants now produce roughly three-quarters of this supply, with the remaining being mined from natural deposits. This method superseded the Leblanc process.

<span class="mw-page-title-main">Carbamate</span> Chemical group (>N–C(=O)–O–)

In organic chemistry, a carbamate is a category of organic compounds with the general formula R2NC(O)OR and structure >N−C(=O)−O−, which are formally derived from carbamic acid. The term includes organic compounds, formally obtained by replacing one or more of the hydrogen atoms by other organic functional groups; as well as salts with the carbamate anion H2NCOO.

<span class="mw-page-title-main">Ammonium carbonate</span> Chemical used as leavening agent and smelling salt

Ammonium carbonate is a salt with the chemical formula (NH4)2CO3. Since it readily degrades to gaseous ammonia and carbon dioxide upon heating, it is used as a leavening agent and also as smelling salt. It is also known as baker's ammonia and is a predecessor to the more modern leavening agents baking soda and baking powder. It is a component of what was formerly known as sal volatile and salt of hartshorn, and produces a pungent smell when baked. It comes in the form of a white powder or block, with a molar mass of 96.09 g/mol and a density of 1.50 g/cm3. It is a strong electrolyte.

Carbonatation is a chemical reaction in which calcium hydroxide reacts with carbon dioxide and forms insoluble calcium carbonate:

Calcium bicarbonate, also called calcium hydrogencarbonate, has the chemical formula Ca(HCO3)2. The term does not refer to a known solid compound; it exists only in aqueous solution containing calcium (Ca2+), bicarbonate (HCO
3
), and carbonate (CO2−
3
) ions, together with dissolved carbon dioxide (CO2). The relative concentrations of these carbon-containing species depend on the pH; bicarbonate predominates within the range 6.36–10.25 in fresh water.

In acid base physiology, the Davenport diagram is a graphical tool, developed by Horace W. Davenport, that allows a clinician or investigator to describe blood bicarbonate concentrations and blood pH following a respiratory and/or metabolic acid-base disturbance. The diagram depicts a three-dimensional surface describing all possible states of chemical equilibria between gaseous carbon dioxide, aqueous bicarbonate and aqueous protons at the physiologically complex interface of the alveoli of the lungs and the alveolar capillaries. Although the surface represented in the diagram is experimentally determined, the Davenport diagram is rarely used in the clinical setting, but allows the investigator to envision the effects of physiological changes on blood acid-base chemistry. For clinical use there are two recent innovations: an Acid-Base Diagram which provides Text Descriptions for the abnormalities and a High Altitude Version that provides text descriptions appropriate for the altitude.

<span class="mw-page-title-main">Alkali soil</span> Soil type with pH > 8.5

Alkali, or Alkaline, soils are clay soils with high pH, a poor soil structure and a low infiltration capacity. Often they have a hard calcareous layer at 0.5 to 1 metre depth. Alkali soils owe their unfavorable physico-chemical properties mainly to the dominating presence of sodium carbonate, which causes the soil to swell and difficult to clarify/settle. They derive their name from the alkali metal group of elements, to which sodium belongs, and which can induce basicity. Sometimes these soils are also referred to as alkaline sodic soils.
Alkaline soils are basic, but not all basic soils are alkaline.

<span class="mw-page-title-main">Concrete degradation</span> Damage to concrete affecting its mechanical strength and its durability

Concrete degradation may have many different causes. Concrete is mostly damaged by the corrosion of reinforcement bars due to the carbonatation of hardened cement paste or chloride attack under wet conditions. Chemical damages are caused by the formation of expansive products produced by various chemical reactions, by aggressive chemical species present in groundwater and seawater, or by microorganisms. Other damaging processes can also involve calcium leaching by water infiltration and different physical phenomena initiating cracks formation and propagation. All these detrimental processes and damaging agents adversely affects the concrete mechanical strength and its durability.

<span class="mw-page-title-main">Ammonium carbamate</span> Chemical compound

Ammonium carbamate is a chemical compound with the formula [NH4][H2NCO2] consisting of ammonium cation NH+4 and carbamate anion NH2COO. It is a white solid that is extremely soluble in water, less so in alcohol. Ammonium carbamate can be formed by the reaction of ammonia NH3 with carbon dioxide CO2, and will slowly decompose to those gases at ordinary temperatures and pressures. It is an intermediate in the industrial synthesis of urea (NH2)2CO, an important fertilizer.

<span class="mw-page-title-main">Carbonic anhydrase</span> Class of enzymes

The carbonic anhydrases form a family of enzymes that catalyze the interconversion between carbon dioxide and water and the dissociated ions of carbonic acid. The active site of most carbonic anhydrases contains a zinc ion. They are therefore classified as metalloenzymes. The enzyme maintains acid-base balance and helps transport carbon dioxide.

<span class="mw-page-title-main">Transition metal carbonate and bicarbonate complexes</span>

Transition metal carbonate and bicarbonate complexes are coordination compounds containing carbonate (CO32-) and bicarbonate (HCO3-) as ligands. The inventory of complexes is large, enhanced by the fact that the carbonate ligand can bind metal ions in a variety of bonding modes.

References

  1. "Impregnation or treatment with carbon dioxide; conversion into a carbonate." Oxford English Dictionary. Oxford University Press. 2018.
  2. Sattler, Wesley; Parkin, Gerard (2012). "Structural Characterization of Zinc Bicarbonate Compounds Relevant to the Mechanism of Action of Carbonic Anhydrase". Chemical Science. 3 (6): 2015. doi:10.1039/c2sc20167d.
  3. "Urea production statistics". www.ifastat.org. International Fertilizer Association. Retrieved 19 April 2023.
  4. Meessen, Jozef H. (2012). "Urea". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a27_333.pub2.
  5. "Henry's Law". ChemEngineering. Tangient LLC. Archived from the original on 2 June 2017. Retrieved 7 November 2017.