Hideki Omichi

A New Type of Amidoxime-Group-Containing Adsorbent for the Recovery of Uranium from Seawater

Abstract A new type of adsorbent containing amidoxime groups for the recovery of uranium from seawater was synthesized by the radiation-induced graft polymerization of acrylonitrile onto polymeric fiber followed by amidoximation with hydroxylamine. When amidoxime groups were introduced superficially on the fiber, the amount of uranium adsorbed by the amidoxime groups was higher than that with the amidoxime groups introduced homogeneously in the fiber. The introduction of the poly(acrylic acid) chain and the increase in temperature and flow rate in the adsorption process were effective in increasing the amount of adsorbed uranium. Although alkali metals and alkaline earth metals were found in the adsorbent, the concentration factors for these metals were less than 1/103 of that for uranium. The present adsorbent had a high stability to various treatments such as contact with alkali and seawater.

A New Type of Amidoxime-Group-Containing Adsorbent for the Recovery of Uranium from Seawater. III. Recycle Use of Adsorbent

Abstract An amidoxime-group-containing adsorbent for recovering uranium from seawater was made by radiation-induced graft polymerization of acrylonitrile onto polymeric fiber, followed by amidoximation. Uranium adsorption of the adsorbent contacted with seawater in a column increased with the increase in flow rate, then leveled off. The relationship between uranium adsorption in a batch process and the ratio of the amount of seawater to that of adsorbent was found to be effective in evaluating adsorbent contacted with any amount of seawater. The conditioning of the adsorbent with an alkaline solution at higher temperature (80°C) after the acid desorption recovered the adsorption ability to the original level. This made it possible to apply the adsorbent to recycle use. On the other hand, the adsorbent conditioned at room temperature or that without conditioning lost adsorption ability during recycle use. The increase in water uptake was observed as one of the physical changes produced during recycle use o...

A New Type of Amidoxime-Group-Containing Adsorbent for the Recovery of Uranium from Seawater. II. Effect of Grafting of Hydrophilic Monomers

Abstract A fibrous adsorbent containing amidoxime groups (AOF) for recovering uranium from seawater was synthesized by the radiation-induced grafting of acrylonitrile (AN) to a fiber followed by the amidoximation of cyano groups of poly(AN) graft chains. When such hydrophilic monomers as N, N-dimethyl-acrylamide (DMAAm) and acrylic acid (AAc) were preliminarily grafted, both the water uptake and the mobility of the sorbed water in AOF were improved in the order: AOF-containing poly-(DMAAm) graft chains (AOF-DMAAm) > AOF-containing poly(AAc) graft chains (AOF-AAc) > AOF without hydrophilic graft chains. The uranium uptake with these adsorbents was, on the other hand, in the order: AOF-AAc > AOF-DMAAm > AOF. The adsorption of alkaline earths was related to the distribution pattern of poly(AAc) graft chains inside the fiber. The adsorbed alkaline earths were eliminated from the adsorbent fiber by introducing a solution of heavy metal ions such as Cu2+.

Thermal control of drug release by a responsive ion track membrane observed by radio tracer flow dialysis

The combination of a responsive hydrogel with a rigid porous supporting structure yield a membrane with high mechanical strength and high on-off-permeability ratio. A membrane consisting of an ion track filter with a thermally responsive lining was prepared by penetrating a 19 micron thick foil of poly(ethylene terephthalate) (PET) with swift heavy ions at a fluence of 5 x 10(5) ions/cm2, followed by etching of the ion tracks to generate an ion track filter with 2.9 micron pore diameter, onto which a thin layer of poly(N-isopropylacrylamide) (NIPAAm) hydrogel was grafted. It was revealed that the mass flow of various molecules (water, chloride-, choline+, insulin, and albumin) through the membrane could be thermally controlled. The on-off-permeability ratio ranged between 3 and 10 increasing with molecular weight. Over a storage time of 5 months the permeabilities varied up to a factor of 2.6, while the on-off-permeability ratio and temperature sensitivity remained practically constant.

Preparation of polyvinylcarbazole thin film with vapor deposition polymerization

N-vinylcarbazole (NVCz) was evaporated toward a substrate of a glass slide coated with silver 100 nm thick with the existence of a redheated filament. The processes of vapor deposition polymerization (VDP) and annealing were observed with in-situ infrared reflection absorption spectroscopy. The filament temperature of 2300 K and the substrate temperature of 266 K were effective to retard the re-evaporation of deposited NVCz. After NVCz was deposited on the above conditions and then annealed at 285 K, the resulting VDP film had a number average molecular weight of 1.1 × 104 and a polymer yield of 88%.

Effect of Shape and Size of Amidoxime-Group-Containing Adsorbent on the Recovery of Uranium from Seawater

Abstract An amidoxime-group-containing adsorbent for the recovery of uranium from seawater was synthesized by radiation-induced graft polymerization of acrylonitrile onto polypropylene fiber of round and cross-shaped sections. The tensile strength and elongation of the synthesized adsorbent, both of which were one-half those of the raw material, were not affected by the shape of the fiber. The deterioration of the adsorption ability induced by immersing the adsorbent in HC1 was negligible because of the short immersion time required for the desorption with HC1. The concentration factors for uranium and transition metals in 28 days were in the order of 105, while those for alkali metals and alkaline earth metals were in the order 10−1-101. The recovery of uranium with the cross-shaped adsorbent was superior to that of the round-shaped one. XMA line profiles show that the distribution of uranium is much restricted to the surface layer when compared with that of alkaline earth metals. Diminishing the diamete...

Reversible on-off switch function of ion-track pores for thermo-responsive films based on copolymers consisting of diethyleneglycol-bis-allylcarbonate and acryloyl-L-proline methyl ester

Abstract Intelligent chemical valves responding to a slight change of temperature were created by the combination of ion beam-chemical etching technique and a novel material consisting of an ion track detector material diethyleneglycol-bis-allylcarbonate (CR-39) and a thermo-responsive gel acryloyl-L-proline methyl ester (A-ProOMe). The changes in size of ion-track pores in etched films were measured microscopically by repetition between 0 and 30°C at 24-h intervals for a 50 μm thick copoly(CR-39/A-ProOMe, 60 40 mol % ) film which was obtained by etching in aqueous 6M NaOH solution at 60°C after an 11.6 MeV/n 208Pb ion irradiation and, as a result, it was found that the pore size in the film obtained by etching for 10 min is reversibly changed from a perfectly closed pore at 0°C to a fully opened pore with a diameter of 0.30 μm at 30°C.

Biodegradable poly(dl-lactic acid) formulations in a calcitonin delivery system

A synthetic analogue of eel calcitonin, [Asu1, 7]-ECT, was incorporated into biodegradable poly(DL-lactic acids) with number-average molecular weights (Mn) of 1400-4400 by the melt-pressing technique. The in vitro release of drug from a parabolically degradable poly(DL-lactic acid) with Mn = 1400 showed an initial burst release and completed the release in 3 d from the start of the test. The drug release from a Mn = 4400 polymer with an S-type degradation pattern was kept at 14 +/- 5 units/d for an experimental period of 24 d.

Light-scattering study of temperature-responsive poly(acryloyl-l-proline methyl ester)

Abstract Poly(acryloyl- l -proline methyl ester) (A-ProOMe) obtained by radiation-induced polymerization exhibited a lower critical solution temperature (LCST) at ca 14°C. Physical properties such as molecular weight ( M W ), particle radius of gyration ( 〈S 2 〉 1 2 ), and particle size distribution were investigated by static and dynamic light-scattering measurements as a function of temperature. The M W of poly (A-ProOMe), obtained by irradiating up to 30 kGy at 25°C, increased from 1,270,000 at 10°C to 56,100,000 at 20°C in water; on the other hand, the 〈S 2 〉 1 2 value decreased with rise in temperature, e.g. from 40.5 to 20.1 nm between 10 and 20°C. From the results of particle size distribution, it was concluded that polymers, dissolved in water below the LCST, aggregate to make globules above LCST.

Application of ion beams to synthesis of environmentally responsive track membranes

Abstract Heavy ion beams with energy in the order of 10 MeV/n were irradiated onto polyethylene terephthalate (PET) and polydiethyleneglycol-bis-allylcarbonate commercially known as CR-39 for producing organic porous membranes. The condition to obtain cylindrical pores was accounted for the relation of restricted energy loss, REL, from ion beams to the polymer films with relative etching rate, Q, in the region along ions trajectory versus non-irradiated region. Then the porous membranes were chemically modified by grafting such monomers as N-isopropylacrylamide and acryloyl-L-proline methyl ester onto the surface of pores to impart the characteristic of the hydrogel obtained from these polymers to the membrane. The pore size of the membrane changed from an open state to a completely closed state when environmental conditions such as temperature were changed. The permeation of water, choline, insulin and albumin through the membrane was controlled by temperature. An abrupt change of permeability was observed at the phase transition temperature of the hydrogel.