Carbonation is thechemical reaction ofcarbon dioxide to givecarbonates,bicarbonates, andcarbonic acid.^[1] Inchemistry, the term is sometimes used in place ofcarboxylation, which refers to the formation ofcarboxylic acids.

Ininorganic chemistry andgeology, carbonation is common.Metal hydroxides (MOH) andmetal oxides (M'O) react with CO₂ to givebicarbonates andcarbonates:

MOH + CO₂ → M(HCO₃)

M'O + CO₂ → M'CO₃

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

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

Inreinforced concrete, the chemical reaction betweencarbon dioxide in the air andcalcium hydroxide and hydratedcalcium silicate in the concrete is known asneutralisation. The similar reaction in which calcium hydroxide from cement reacts with carbon dioxide and forms insoluble calcium carbonate iscarbonatation.

Carbonation of ammonia is one step in the industrial production ofurea. 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

Henry's law states that P_CO2=K_Bx_CO2 where P_CO2 is the partial pressure of CO₂ gas above the solution. K_B is Henry's law constant. K_B increases as temperature increases. x_CO2 is themole 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 {P_CO2/x_CO2 = K_B} and both these two conditions support increase in carbonation.

• Inorganic chemistry
• Transition metals
• Coordination complexes

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