Radiation-induced graft polymerization is a powerful method for modifying existing polymers of various shapes and qualities. We have thus far applied this method to the functionalization of polyethylene porous hollow-fiber membrane and sheet. A polymer chain with ion-exchange groups was grafted onto porous polymers uniformly across the entire volume. The confinement of the graft chain to a porous structure enabled us to characterize the graft chain. The graft chain can be classified into polymer root invading the polymer matrix and polymer brush extending from the pore surface toward the pore. The polymer root swelled the entire volume of the porous material, resulting in abbreviation of the pore volume reduction, whereas the polymer brush captured proteins in multilayers via multipoint binding. The introduction of the functional group into the epoxy group of poly-glycidyl methacrylate graft chain in a shrunken conformation provided a size-exclusive layer for the upper domain of the graft chain. Also, an adequate selection of solvents for the introduction of the ion-exchange group led to the determination of the ratio of the polymer brush to the polymer root.

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Arsenate species and nitrate are hazardous anions, which cause cancer and serious diseases. Phosphate species and nitrate are non-environment-friendly anions because they trigger eutrophication in lakes and rivers. Therefore, it is important to search for and develop kinetically excellent organic adsorbents selective to these anions. In this work, we found that crosskinked polyallylamine beads (PAA) selectively took up phosphate and arsenate species in the presence of chloride and sulfate. It was also clarified that a PAA packed column could take up phosphate species under fast feed flow rates of 300～2400 h⁻¹ in space velocity (SV). Referring to these findings, weak-base anion exchange fibers (FVA) containing polyvinylamine chains were prepared by means of alkaline hydrolysis of formamide moieties on polyvinylformamide grafted fibers, which were prepared by means of electron irradiation induced graft polymerization of vinylformamide onto polyolefin fibers (PPPE). The resulting FVA selectively took up arsenate species in the presence of chloride and sulfate, and an FVA packed column also took up arsenate species under fast feed flow rates of 100～1050 h⁻¹ in SV. Furthermore, kinetically excellent nitrate selective anion exchange fibers, FTAA and FTHA, were prepared by quaternization of polychloromethylstyrene grafted polyolefin fiber (PPPE-g-CMS) with triamylamine and trihexylamine, respectively; here, the precursor, PPPE-g-CMS, was prepared by means of electron irradiation induced graft polymerization of chloromethylstyrene onto PPPE. The resulting FTAA and FTHA were able to rapidly take up nitrate in column-mode even at the high feed flow rate of 500～3000 h⁻¹ in SV. Chloride, bicarbonate and sulfate up to 5 times the nitrate molarity did not interfere with the uptake of nitrate. Three kinds of anion exchangers described here were able to be used repeatedly through adsorption-elution-regeneration operations.

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In the process of the Kraft Chemical Recovery Cycle, Chloride and Potassium that enter the process in raw-material wood chips gradually accumulat and are concentrated during continuous operation. The issue of carryover particles and dust blocking the Recovery Boiler is caused by the decreasing melting temperature of dust along with the increasing concentration of Chloride and Potassium in the Black Liquor. At the same time, fouling and corrosion of the super heater in the Recovery Boiler is checked. This manuscript provides actual results from the Chloride & Potassium Removal System, which was developed and installed at the Niigata Mill, Hokuetsu Paper Mills, Ltd, together with the theory for a removal system using ion exchange resin all of which are characteristics of this system and advantages from the aspect of saving energy.

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The material for removing, recovering and fixing of the cesium etc. which were emitted by the accident of the Fukushima Daiichi nuclear power plant into environment is needed. Authors' research group has developed a new cesium adsorption and fixation material based on an autoclaved lightweight concrete (ALC) that consists of tobermorite. High cesium removal performance is revealed by hydrothermal treatment of a tobermorite with sodium hydroxide. In this paper, cesium and strontium removal performance of the powder and the bulk of this NaOH treated ALC sample and the removal performance of cesium and strontium from the sea water by these samples are explained.

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A method for disposing of high-level radioactive waste (HLW) derived from spent nuclear fuel from a fast breed reactor (FBR) is required. The separation and recovery of long-lasting minor actinides (MAs), such as Am and Cm, from HLW is important in order to reduce the environmental burden and prevent the dumping of radioactive wastes. In recent years, extraction chromatography has been studied for the purpose of separation and recovery, including the separation of long-lasting MAs and specific fission products (FPs). However, HLW, including MA, generates radiolytic gas and sludge in the column during chromatographic separation, and both have a detrimental effect on separation capacity. We investigated expanded-bed chromatography and obtained valuable data on elution behaviors. From these experiments, it was found that expanded-bed chromatography reduces the influence of radiolytic gas and sludge on separation capacity.

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