Discuss briefly the demineralization of water by ion exchange resin.

(N/A) Demineralization of water is achieved by passing water through cation and anion exchange resins.
$1$. Cation exchange resin: These resins contain large organic molecules with $-SO_{3}H$ groups. In the $H^{+}$ form,they exchange $H^{+}$ ions for cations like $Na^{+}, Ca^{2+},$ and $Mg^{2+}$ present in water.
$2 RH_{(s)} + M^{2+}_{(aq)} \rightleftharpoons MR_{2(s)} + 2H^{+}_{(aq)}$
This process makes the water acidic due to the release of $H^{+}$ ions.
$2$. Anion exchange resin: These resins contain basic groups like $-NH_{2}$ or $-OH$ groups. They exchange $OH^{-}$ ions for anions like $Cl^{-}, HCO_{3}^{-},$ and $SO_{4}^{2-}$ present in water.
$RNH_{2(s)} + H_{2}O_{(l)} \rightleftharpoons RNH_{3}^{+}OH^{-}_{(s)}$
$RNH_{3}^{+}OH^{-}_{(s)} + X^{-}_{(aq)} \rightleftharpoons RNH_{3}^{+}X^{-}_{(s)} + OH^{-}_{(aq)}$
$3$. Neutralization: The $OH^{-}$ ions released from the anion exchange resin neutralize the $H^{+}$ ions released from the cation exchange resin to form pure water.
$H^{+}_{(aq)} + OH^{-}_{(aq)} \longrightarrow H_{2}O_{(l)}$
The exhausted resins are regenerated using dilute acid and alkali solutions.