Isotope effects of iron in Fe (II) -Fe (III) electron exchange system were studied using anion exchange chromatography. It was found that the heavier isotope is enriched at the rear part of the iron adsorption band. The results indicate that the heavier isotope is preferentially fractionated in Fe (III) chloride complex ions in the anion exchange resin phase. The single stage separation coefficient, ε, observed for ⁵⁷Fe/⁵⁶Fe isotopic pair was 2.06×10^-4 at 333 K. The height equivalent to theoretical plate was calculated to be 0.68mm.

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Intercalation of (3-aminopropyl) triethoxysilane, AMPS, into cerium (IV) hydrogenphosphate (CeP) was investigated by X-ray diffractometry, chemical and thermal analysis, ²⁹Si MAS NMR, and FTIR. AMPS intercalated up to 1.2 mol per phosphate accompanied by hydrolysis of the ethoxy groups and the interlayer spacing of the CeP enlarged from 1.1nm to 1.7nm. The ²⁹Si MAS NMR spectra revealed that the AMPS undergoes polymerization and AMPS octamer, [NH₂ (CH₂) ₃SiO_1.5-O (OH) Si (CH₂) ₃NH₂] ₄, is formed in the interlayer space of CeP. Infrared spectra showed that the aminopropyl group exists as an ammonium form. On the basis of the relation between the uptake of metal ions and the leached amount of AMPS, the intercalated AMPS octamers was found to be exchanged with divalent metal cations stoichiometrically. Selectivity for the divalent metal ions increases with the following order; Ca²⁺>Sr₂₊>Ba²⁺>Cu₂₊>Co²⁺>Ni²⁺. This order agrees with that of the octylamine-intercalated CeP.

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wide varieties of Ion Exchange Resins are commercially produced at present. Their fundamental polymer structures are classified into gel type and macro-porous type from the point of physical structure. In this paper, I will brief on the preparation methods for macro-porous structure and their features of each preparation approach.
I will also touch on recent commercial resins having unique macro-porous structure.

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Development of novel ion-exchange resins is continuing to improve their performance of ionexchange rate, capacity, and durability. For example, porous ion-exchange resins of a hollowfiber membrane form were prepared by radiation-induced grafting of polymer brushes and subsequent chemical modifications. The ion-exchange resins exhibited a higher rate and capacity for protein capturing than conventional ion-exchange beads because of convective transport of the protein through the pores and multilayer binding of the protein to the ion-exchange polymer brushes.

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