Patent ID: 10518219

Abstract:
A process for ion-exchanging an exchangeable-ion containing solid material, characterized in that said process include a bipolar membrane electrodialysis step, which comprises subjecting an aqueous ion-containing solution to a bipolar membrane electrodialysis to produce an acid liquid; an ion-exchange step, which comprises contacting the exchangeable-ion containing solid material with the acid liquid and conducting the ion-exchange to produce a slurry containing the ion-exchanged solid material; a solid-liquid separation step, which comprises subjecting the slurry containing the ion-exchanged solid material to a solid-liquid separation to produce a solid phase and a liquid phase, adjusting the liquid phase to a pH of 4-6.5, and subjecting the pH-adjusted liquid phase to a solid-liquid separation to produce a treatment liquid. Oxalic acid is used in at least one of the bipolar membrane electrodialysis step, the ion-exchange step, and the solid-liquid separation step.