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Each mole of CO 2 (44 g) reacts with one mole of calcium hydroxide (74 g) and produces one mole of water (18 g). The reaction can be considered as a strong-base-catalysed, water-facilitated reaction. [5] The reaction mechanism of carbon dioxide with soda lime can be decomposed in three elementary steps:
As lime in the form of limewater is added to raw water, the pH is raised and the equilibrium of carbonate species in the water is shifted. Dissolved carbon dioxide (CO 2) is changed into bicarbonate (HCO − 3) and then carbonate (CO 2-3). This action causes calcium carbonate to precipitate due to exceeding the solubility product.
This is accomplished by heating the material to above 825 °C (1,517 °F), [6] [7] a process called calcination or lime-burning, to liberate a molecule of carbon dioxide (CO 2), leaving quicklime behind. This is also one of the few chemical reactions known in prehistoric times. [8] CaCO 3 (s) → CaO(s) + CO 2 (g)
The equilibrium of CO 2 moves to the right, toward gaseous CO 2, when water temperature rises or pressure falls. When water that contains dissolved calcium carbonate is warmed, CO 2 leaves the water as gas, this reduces the amount involved in the reaction causing the equilibrium of bicarbonate and carbonate to re-balance to the right ...
Carbonatation is a slow process that occurs in concrete where lime (CaO, or Ca(OH) 2 ) in the cement reacts with carbon dioxide (CO 2) from the air and forms calcium carbonate. The water in the pores of Portland cement concrete is normally alkaline with a pH in the range of 12.5 to 13.5.
Brine draw: Water is directed through a jet pump, which pulls salt water from the brine tank, before the water and brine pass through the resin bed in the normal direction, if co-current, or in the reverse direction, if counter-current. [12] The output of this typically thirty-minute process is discarded through the drain hose.
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This reaction can take place at anywhere above 840 °C (1,540 °F), but is generally considered to occur at 900 °C (1,650 °F) (at which temperature the partial pressure of CO 2 is 1 atmosphere), but a temperature around 1,000 °C (1,830 °F) (at which temperature the partial pressure of CO 2 is 3.8 atmospheres [1]) is usually used to make the ...