A new ion exchange membranes were developed using the graft polymerization method, and their mass production technology was established. The developed ion exchange membrane has excellent concentration performance, ion selective permeability, and film-like supple properties compared to the conventional ion exchange membranes based on woven PVC fibers.

Electrodeionization (EDI) enables continuous ion-exchange resin regeneration without chemical reagents and is now applied to advanced ultrapure water production. A major issue is CO₂ leakage from the concentrate compartment, where concentrated CO₂ diffuses into the dilute compartment and degrades product-water purity. We developed a redesigned module structure that suppresses CO₂ diffusion and eliminates its current-dependent leakage behavior, achieving an extremely low CO₂ level in the product water. This technology has been implemented in the high-purity XP model of the EDISTA^TM series and is being installed in advanced ultrapure water facilities.

In this study, an adsorbent was synthesized using 4’,4’(5’’)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6), dodecanol and SiO₂-P. The (DtBuCH18C6+dodecanol)/SiO₂-P adsorbent is known to have high adsorption properties for strontium, and experiments were conducted on the adsorption properties under gamma irradiation.

Experimental results showed that the adsorbent adsorbed strontium even under gamma irradiation. Regarding the stability of adsorbents under irradiation, it was found that the carbon retention of the adsorbent decreased linearly with increasing absorbed dose, assuming that all eluted carbon was derived from the impregnated extractants and modifiers. The results obtained for the adsorption performance of the irradiated adsorbent showed that the adsorption performance of the target adsorbent tended to decrease with increasing absorbed dose. The metal and carbon retentions of the adsorbents decreased linearly with increasing absorbed dose, but the decrease in carbon retention relative to the adsorbent dose was suppressed for the adsorbed metal.