Criterion of ion separation by reverse osmosis

摘要

AbstractThe order of ion separation by the NS‐100 membrane differed slightly from that of the cellulose acetate membrane. The separation of an ion by the NS‐100 membrane increased with increase in the valence of the ion, but decreased with the increase in the ionic radius. The sole criterion determining this separation order for the NS‐100 membrane was the enthalpy of hydration. An ion having a higher enthalpy of hydration is bulkier in the hydrated form and is, therefore, separated more effectively by the NS‐100 membrane, according to the diffusional model of solute separation. The permeability of an ion through the membrane material can be related to its enthalpy of hydration. By using this relationship, the separation of individual ions in aqueous solution with a given NS‐100 membrane can be predicted from a test with a sodium chloride