Carbonation is the chemical reaction of carbon dioxide to give , , and carbonic acid.["Impregnation or treatment with carbon dioxide; conversion into a carbonate."] In chemistry, the term is sometimes used in place of carboxylation, which refers to the formation of .
In inorganic chemistry and geology, carbonation is common. (MOH) and (M'O) react with CO2 to give and :
- MOH + CO2 → M(HCO3)
- M'O + CO2 → M'CO3
Selected carbonations
Carbonic anhydrase
In mammalian 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:
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.
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.
In the subsequent urea conversion: the ammonium carbamate is decomposed into urea, releasing water:
Solubility
Henry's law states that P
=K
Bx
where P
is the partial pressure of gas above the solution. K
B is Henry's law constant. K
B increases as temperature increases. x
is the
mole fraction of gas in the solution. According to Henry's law carbonation increases in a solution as temperature decreases.
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 {P/x = KB} and both these two conditions support increase in carbonation.
