Why do you have cation exchange first and anion exchange later in ion exchange and not the other way around?

Question

Accepted Answer

Cation exchange is done first in ion exchange because cations are more easily exchanged than anions.

Cations have a higher affinity for the exchange resin than anions.
Cations are generally smaller in size and have a higher charge density, making them more easily exchanged.
Anions are larger and have a lower charge density, making them less easily exchanged.
Cation exchange is often used to remove heavy metal cations from water, while anion exchange is used to remove anions like nitrates or sulfates.
The order of cation exchange followed by anion exchange ensures efficient removal of both cations and anions.

Accepted Answer

Keeping anion exchange will form hydroxides of Mg and Ca ions and cough up the exchange column.

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