For the purpose of efficient separation of metal ions dissolved in aqueous solutions, various separation materials have been synthesized and investigated their selectivity. For solvent extraction, negatively charged multidentate ligands were synthesized and their separation behavior was researched. In order to improve the selectivity of metal ions in aqueous solution, solvent extraction system was added octadecyl surface-modified silica gel (ODS-Silica). And also investigated the separation and the extraction behavior of ODS-Silica loaded with the solvent extraction reagent. In the system using negative divalent hexadentate reagent (H2Clbbpen) as the solvent extraction reagent, the extractability and selectivity were improved in both systems. TTA and Dithizone were selected as solvent extraction reagents to research the adsorption and separation of transition metal ions and noble metals, respectively. As an inexpensive separation material, banana fiber was focused and examined the selectivity of natural or chelated fiber. Banana fiber was chemically bonded with several Schiff base derivatives was found to be able to adsorption transition metal ions, but the selectivity and adsorption capacity were low. Banana fiber showed the ability to collect cesium and strontium, but its low heat resistance made it difficult to use. In this paper, the results of investigations on the adsorption capacity and selectivity of each separation material were described.
We have developed a new type monolithic ion exchange resin which has a co-continuous porous structure, and we have been applying it for water treatment and for synthetic catalyst use. The pore structure was obtained by a two-step polymerization process. In the first step, an open-celled porous styrene-divinylbenzene copolymer was synthesized by preparation of water-in-oil (W/O) emulsion followed by polymerization. In the second step, the obtained copolymer was soaked and polymerized in a solution containing styrene, divinylbenzene, and a polymeric initiator. In order to obtain the monolithic ion exchange resin, functional groups, such as sulfonic acid and trimethylammonium, were introduced into the copolymer. The ion exchange capacity of both monolithic cation exchange resin (CEMR) and anion exchange resin (AEMR) were over 4 meq/g. The ion exchange band length of the monolithic ion exchange resins were approximately 10 times shorter than that of conventional ion exchange resin columns. Pd-supported AEMR (Pd/AEMR) was able to decompose hydrogen peroxide generated in the ultrapure water production line efficiently, and the treatment flow rate could be raised to approximately 10 times that of the Pd-supported cation exchange resin (Pd/CEMR). Pd/AEMR showed catalytic activity in hydrogenation reactions and coupling reactions, and in the continuous flow hydrogenation reaction using Pd/AEMR, higher yield was obtained in a shorter time than in batch reaction.
A novel core-shell ion-exchange resin (St-80) having a 20:80 weight ratio of the monomer for the core and the shell was prepared for use in high-performance liquid chromatography (HPLC), and the effect of the degree of cross-linking (10–55%) of the porous shell on the separation of carbohydrates was examined. A mixed aqueous sample of inositol, glucose, fructose, and sucrose was reasonably separated under strong alkaline conditions (0.10 and 0.15 mol/L NaOH eluent) at flow rates of 0.3–0.7 mL/min. As the degree of cross-linking in the shell portion increased, the retention time of sucrose, which had the longest elution time, decreased. Meanwhile, the theoretical plate number nearly doubled. The retention times obtained for the high degrees of cross-linking (40% and 55%) in the porous shell were shorter than that of the fully porous resin. The theoretical plate number observed for these resins provided excellent resolution, similar to that of the fully porous resin.