瀬古 典明*; 保科 宏行*; 笠井 昇*; 柴田 卓弥; 佐伯 誠一*; 植木 悠二*
Radiation Physics and Chemistry, 143, p.33 - 37, 2018/02
Six years after the Fukushima-nuclear accident, the dissolved radioactive cesium (Cs) is now hardly detected inenvironmental natural waters. These natural waters are directly used as source of drinking and domestic waters in disaster-stricken areas in Fukushima. However, the possibility that some radioactive Cs adsorbed on soil or leaves will contaminate these natural waters during heavy rains or typhoon is always present. In order for the returning residents to live with peace of mind, it is important to demonstrate the safety of the domestic waters that they will use for their daily life. For this purpose, we have synthesized a material for selective removal of radioactive Cs by introducing ammonium 12-molybdophosphate (AMP) onto polyethylene nonwoven fabric through radiation-induced emulsion graft polymerization technique. Water purifiers filled with the grafted Csadsorbent were installed in selected houses in Fukushima. The capability of the grafted adsorbent to remove Cs from domestic waters was evaluated for a whole year. The results showed that the tap water filtered through the developed water purifier contained no radioactive Cs, signifying the very effective adsorption performance of thedeveloped grafted adsorbent. From several demonstrations, we have commercialized the water purifier named "KranCsair".
柴田 卓弥; 瀬古 典明; 天田 春代; 笠井 昇; 佐伯 誠一; 保科 宏行; 植木 悠二
Radiation Physics and Chemistry, 119, p.247 - 252, 2016/02
A fibrous adsorbent for radioactive cesium (Cs) removal has been developed by radiation induced graft polymerization. To apply the developed adsorbent to drinking water, the stability of adsorbent having high affinity for Cs ligand, ammonium 12-molybdophosphate (AMP), was evaluated. As a result, since a crosslinking structure was introduced onto the grafted AMP, it could be successfully satisfied the regulation of Food Sanitation Act. Finally, the Cs adsorbent was commercialized as water purifier named by "KranCsairtextregistered".
瀬古 典明; 柴田 卓弥; 笠井 昇; 植木 悠二; 佐伯 誠一; 保科 宏行
放射線と産業, (138), p.9 - 12, 2015/06
柴田 卓弥; 瀬古 典明; 笠井 昇; 保科 宏行; 植木 悠二
International Journal of Organic Chemistry, 5(2), p.100 - 107, 2015/06
To obtain the safety of drinking water, an antibacterial material was prepared by loading Ag onto fibrous iminodiacetate (IDA) adsorbent, which was synthesized by radiation induced graft polymerization of a glycidyl methacrylate and subsequent chemical modification of the produced epoxy group to an IDA group(IDA-Ag). A total amount of loaded Ag on the IDA-Ag fabric was 0.4 mmol-Ag/g-fabric. As a result of evaluating antibacterial effects by the column mode water flow test with a stream water, the effective Ag concentration was monitored 0.05 ppm at irrespective of flow rate which was functioned to the antibacterial performance. The antibacterial effects for general bacteria were indicated until BV (BV: steam water volume/IDA-Ag fabric volume) 6,000, and for colitis germ legions were completely disinfected until BV 6,000.
柴田 卓弥; 瀬古 典明; 天田 春代; 笠井 昇; 佐伯 誠一; 保科 宏行; 植木 悠二
日本イオン交換学会誌, 26(1), p.9 - 14, 2015/01
It is important task for recovering of Cs from the contaminated area caused by the accident at the Fukushima Daiichi Nuclear Power Station. We developed a highly efficient Cs adsorbent by radiation grafting of ammonium 12-molybdophosphate (AMP) and crosslinking of grafted chains with a suitable crosslinker at the same time. As a result of the optimizaion, the Cs adsorbent with 1 mol% of polyethylene glycol dimethacrylate satisfied the specification as a water purifier. The resultant grafted Cs adsorbent could work to maintain the highly performance of Cs removal in the standard pH range for drinking water (from pH 5.8 to 8.6) and even in the presence of coexisting ions such as K, Ca, Mg, and Na.
佐伯 誠一; 柴田 卓弥; 保科 宏行; 植木 悠二; 笠井 昇; 瀬古 典明
日本イオン交換学会誌, 25(4), p.170 - 175, 2014/11
After Fukushima Daiichi Nuclear Power Plant accidents, a lot of contaminated wastes have been produced by decontamination works at contaminated areas around Fukushima prefecture, Japan. At some temporary storage sites, it was found that contaminated leaching water was accumulated under stacks of contaminated "plant" wastes. To handle the wastes and the solution properly, decontamination tests of the leaching water were examined with molybdophosphate type cesium adsorbents synthesized by radiation-induced grafting method. At batch adsorption tests, 75% of radioactive cesium was successfully removed with cesium adsorbents. At column adsorption tests, radioactivity concentration of the leaching water could be reduced under provisional limit value up to around 500 times volume as large as an adsorbent volume. For development of volume reduction method of contaminated plant wastes, radioactive cesium extraction tests from the wastes and removal tests from the extracts were executed using contaminated oil cakes of sunflower seeds as a model of contaminated plant wastes. As a result, 65% of radioactive cesium was successfully extracted from the oil cakes to liquid phase, and more than 65% of radioactive cesium could be collected from the extract by grafted cesium adsorbents. These results showed a possibility of an application of these processes to volume reduction method for contaminated plant wastes.
林 菜月*; 保科 宏行; 天田 春代; 山延 健*; 瀬古 典明
日本イオン交換学会誌, 25(4), p.105 - 108, 2014/11
A fibrous phosphoric acid adsorbents for scandium were synthesized by radiation graft polymerization of glycidyl methacrylate (GMA), subsequent chemical modification, and direct grafting with a phosphoric monomer having both vinyl and phosphoric groups onto a polypropylene coated by polyethylene nonwoven fabric. The resultant grafted fibrous phosphoric acid adsorbent (HMP-g) having long side grafted chains has high affinity for scandium (Sc) ions even under the coexistence with Fe ion. The breakthrough capacity for Sc of 0.5 ppm with Fe coexistence was 10.9 mol-Sc per kg-adsorbent for the GMA derivative phosphoric adsorbent, and 17.8 mol-Sc per kg-adsorbent for HMP-g, respectively.
保科 宏行; 笠井 昇; 天田 春代; 高橋 牧克*; 田中 和也*; 瀬古 典明
日本イオン交換学会誌, 25(4), p.248 - 251, 2014/11
An adsorbent for Scandium (Sc) recovery was developed with radiation-induced graft polymerization of phosphoric acids that have a high affinity for Sc onto polyethylene fabrics. The adsorption performance of Sc was evaluated with the Sc adsorption equipment, consisting of 155 mm internal diameter columns and a pump that were set up near Yukawa River in Kusatsu town. To achieve a practical use of Sc recovery, the adsorbent requires repeated use with maintaining its efficiency in terms of cost reduction. So, the reusability of the adsorbent was investigated by repeating adsorption and elution. The breakthrough curves of Sc adsorption showed similar behavior in all tests. The adsorbed Sc from the 19th adsorption test was 56 mg, which was comparable capacity to the average amount of the adsorbed Sc during the 19 tests. These results indicated that the adsorbent was used more than 19 times with maintaining high adsorption performance of Sc.
天田 春代; 高橋 牧克*; 保科 宏行; 瀬古 典明
日本イオン交換学会誌, 25(4), p.109 - 113, 2014/11
A large amount of arsenic waste solution which was dissolved in neutral aqueous media, was generated from the manufacturing process of gallium arsenide component in semiconductor industry. As for arsenic removal, an adsorbent was developed by radiation graft polymerization and subsequent chemical modification with N-methyl-D-glucamine (NMDG) as a functional group. Furthermore, the grafting and the modification were carried out using water based solvent instead of organic solvent in view of an environmental emission and a working environment. The solvents were comprised of water and surfactant, and the adsorption performances compared with a conventional method synthesized in 1,4-dioxane of organic solvent. Total amount of arsenic for arsenic(III) and arsenic(V) at pH 6.5 were 3.2 times and 2.1 times higher than our previous fibrous adsorbent. From the pH dependency studies, the developed grafted adsorbent gave high removal ratio in a neutral media area for both arsenic species. Breakthrough capacities in the column mode tests for arsenic(III) and arsenic(V) were 0.3 and 18 mg/g at pH 6.5, respectively.
保科 宏行; 植木 悠二; 佐伯 誠一; 瀬古 典明
International Journal of Organic Chemistry, 4(3), p.195 - 200, 2014/09
2-Ethylhexyl hydrogen-2-ethylhexylphosphonate (EHEP) is commonly used as a metal extractant because it has a particular affinity for rare-earth metals like Scandium (Sc). To develop a highly-selective polymeric adsorbent of Sc(III), EHEP was introduced as a functional group onto a polyethylene fabric with radiation-induced graft polymerization (RIGP). The adsorption performances for Sc(III) were evaluated in aqueous solutions containing Sc(III) and Fe(III) by a column test. The adsorption capacities of Sc(III) and Fe(III) until the bed volume reached 5000 were 5.22 and 0.12 mg/g, respectively. The adsorbents showed 44 times higher Sc(III) adsorption capacity than that of Fe(III). These results indicated that the grafted adsorbent containing EHEP had an extremely high selectivity for Sc(III) adsorption.
植木 悠二; 佐伯 誠一; 柴田 卓弥; 保科 宏行; 笠井 昇; 瀬古 典明
International Journal of Organic Chemistry, 4(2), p.91 - 105, 2014/06
笠井 昇; 岩撫 暁生; 植木 悠二; 佐伯 誠一; 保科 宏行; 瀬古 典明
JAEA-Technology 2013-046, 25 Pages, 2014/02
Ma, H.*; Chi, H.*; Wu, J.*; Wang, M.*; Li, J.*; 保科 宏行; 佐伯 誠一; 瀬古 典明
Applied Materials & Interfaces, 5(17), p.8761 - 8765, 2013/09
Gold nanostructured microtubes (AuNMTs) are prepared using a tertiary amine group-functionalized polyethylene (PE)-coated polypropylene (PP) nonwoven fabric as a ligand, a reductant, and a template, which takes advantage of the different radiation effects of PE and PP. The Au(III) ions are absorbed and reduced only in the PE layer to form the aggregation of gold nanoparticles; thus, AuNMTs are obtained after the calcination.
保科 宏行; 高橋 牧克*; 笠井 昇; 瀬古 典明
International Journal of Organic Chemistry, 2(3), p.173 - 177, 2012/09
A fibrous adsorbent for arsenic (As) removal was synthesized with nonwoven cotton fabric as a trunk polymer. Phosphoric acid monomer was reacted by radiation-induced graft polymerization onto nonwoven cotton fabric. The degree of grafting of 130% was obtained at irradiation dose of 20 kGy with 5% of monomer solution for 2 hours reaction time at 40C reaction temperature. After the grafted material was contacted with 10 mmol/L of zirconium (Zr) solution at pH1, 0.38 mmol/g of Zr as a functional group was loaded on the grafted phosphoric units for As(V) removal. The resulting adsorbent was evaluated by column mode adsorption with 1 mg/L of As(V) solution at various pH with space velocity 200 h. The maximum capacity of As(V) adsorption was 0.1 mmol/g at pH2.
岩撫 暁生; 笠井 昇; 保科 宏行; 植木 悠二; 佐伯 誠一; 瀬古 典明
Journal of Radioanalytical and Nuclear Chemistry, 293(2), p.703 - 709, 2012/08
保科 宏行; 笠井 昇; 柴田 卓弥*; 明田川 康*; 高橋 牧克*; 吉井 明央*; 角田 安彦*; 瀬古 典明
Radiation Physics and Chemistry, 81(8), p.1033 - 1035, 2012/08
The zirconium (Zr(IV))-type adsorbent for As(V) removal was synthesized by radiation-induced graft polymerization with phosphoric monomer and the subsequent chemical modification with Zr(IV) by loading on phosphoric units. The Zr(IV)-type adsorbent can rapidly remove As(V) to low concentration. In order to apply for a large amount of water treatment, it is necessary to construct of synthesis method in pilot scale. Synthesis method of graft adsorbent in pilot scale was investigated by setting up the equipment which was composed of reaction tanks, washing tank and pump. The equipment can produce the adsorbent which is maximum 0.3 20 m size in one batch graft reaction. To evaluate the optimum condition in this equipment, it was required the optimization of several condition such absorbed dose, monomer concentration, reaction temperature and reaction time. A nonwoven cotton fabric as a trunk polymer was irradiated, then it was placed into the reaction tank with the deaerated monomer solution. The components of the monomer was phosphoric acid mono- (50%) and di- (50%) ethyl methacrylate ester. As a result, the degree of grafting of 150% was obtained at absorbed dose of 20 kGy with 5% monomer solution mixed by deionized water for 2 hours at 40 C. Finally after loaded of Zr(IV) on grafted nonwoven fabric, As(V) adsorbent was achieved in pilot scale.
Suwanmala, P.*; Hemvichian, K.*; 保科 宏行; Srinuttrakul, W.*; 瀬古 典明
Radiation Physics and Chemistry, 81(8), p.982 - 985, 2012/08
Metal adsorbent containing hydroxamic acid groups was successfully synthesized by radiation-induced graft copolymerization of methylacrylate onto cassava starch. The optimum conditions for grafting were studied in terms of % degree of grafting (Dg). Conversion of the ester groups present in poly(methyl acrylate)-grafted-cassava starch copolymer into hydroxamic acid was carried out by treatment with hydroxylamine in the presence of alkaline solution. The adsorbent of 191%Dg had total adsorption capacities of 2.6, 1.5, 1.4, 1.2 and 1.6 mmol/g-adsorbent for Cd, Al, UO, V, and Pb, respectively, in the batch mode adsorption.
植木 悠二; Dafader, N. C.*; 保科 宏行; 瀬古 典明; 玉田 正男
Radiation Physics and Chemistry, 81(7), p.889 - 898, 2012/07
By finding optimum grafting conditions, radiation-induced graft polymerization of glycidyl methacrylate (GMA) onto non-woven polyethylene (NWPE) fabric was achieved under normal pressure and air atmospheric conditions, even when a polyethylene bottle was used as a reactor instead of unique apparatus such as glass ampoules or vacuum lines. The optimum grafting conditions in this paper were as follows; the pre-irradiation dose was more than 50 kGy, the volume ratio of GMA-emulsion to air was 50:1 or less, and the dissolved oxygen concentration in GMA-emulsion during grafting was below 2.0 mg/L, respectively. Under these grafting conditions, the grafting yield was controlled up to 362%. The prepared GMA-grafted NWPE (GMA-g-NWPE) fabric was modified with a phosphoric acid to obtain a fibrous metal adsorbent. In the column-mode adsorption tests of Pb(II), the adsorption performance of the fibrous metal adsorbent was not essentially dependent on the flow rate of the feed. The breakthrough points of 200, 500, and 1000 h in space velocity were 483, 477 and 462 bed volumes, and the breakthrough capacities of the three flow rates were 1.16, 1.15 and 1.16 mmol-Pb(II)/g-adsorbent, respectively.
笠井 昇; 保科 宏行; 瀬古 典明; 柴田 卓弥*; 高橋 牧克*
JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 46, 2012/01
Ma, H.; 森田 和明*; 保科 宏行; 瀬古 典明
Materials Sciences and Applications, 2(7), p.777 - 785, 2011/07
A pre-irradiation method was used for emulsion graft polymerization of 4-hydroxybutyl acrylate glycidylether (4-HB) onto polyethylene/polypropylene (PE/PP) nonwoven fabric. The degree of grafting (D) which can be calculated by weight increment was determined as a function of reaction time, irradiation dose, and monomer concentration. After 30 kGy irradiation, with 4-HB concentration of 5%, surfactant Span 20 of 0.5% at 40C for 2 h, the trunk polymer was made grafted at a D of 135%. 4-HB-grafted PE/PP nonwoven fabric was modified by ethylenediamine (EDA) in isopropyl alcohol (IPA) as a solvent at 60C. The removal ratio from the EDA modified adsorbent of the metal ions is in the order of Cu Pb Zn Ni Li. Compared with glycidyl methacrylate (GMA) which is a typical functional monomer for graft polymerization, 4-HB-grafted adsorbent exhibited not only better mechanical property but also higher adsorption capacity of Cu and Pb.