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Parajuli, D.; Hirota, Koichi; Seko, Noriaki; Oto, Keisuke*
Proceedings of 12th International Conference on Environmental Science and Technology (CEST 2011), p.B835 - B842, 2011/09
Cotton consisting of nearly 100% cellulose is one of the widely available natural polymers with versatile applications. In order to know the possibility of using cellulosic materials for the development of functional adsorbents by radiation induced vinyl graft modification method, cotton was studied as a representative natural material. In the present study, cotton was pre-irradiated with electron beam and glycidyl methacrylate (GMA) was grafted onto it. Various parameters like irradiation dose, solvent system, monomer concentration, grafting time, etc were studied to achieve the optimum graft yield. Once GMA containing reactive epoxy group was grafted onto the cotton matrix, various functional groups possessing different selectivity behavior for different metals were introduced by simple chemical reaction. The newly developed functional-cotton derivatives were studied for their ion exchange performances and selectivity patterns mainly for palladium in HCl and HCl-HNO
systems.
Hirota, Koichi; Parajuli, D.; Seko, Noriaki
Proceedings of 12th International Conference on Radiation Curing in Asia (RadTech Asia 2011) (Internet), p.136 - 137, 2011/06
Conventional methods for the recovery of precious metals are solvent extraction, chemical precipitation, and use of ion exchange resins. However these methods are facing to significant disadvantages like high capital costs, large chemical and energy requirements, and generation of toxic sludge or other waste products creating additional burden. Development of biomass based sorbents is a better, probably the best, option with lower capital cost and higher efficiency. Although the biomass-sorbents are better than the existing methods, the methods of preparing sorbents from them usually use several kinds of chemicals. In the present work, biomass has been modified with functional groups after electron beam irradiation and its performance for the recovery of precious metals has been studied. The obtained results are compared with that of chemically modified derivative.
Parajuli, D.; Hirota, Koichi; Seko, Noriaki
Journal of Radioanalytical and Nuclear Chemistry, 288(1), p.53 - 58, 2011/04
Times Cited Count：19 Percentile：78.71(Chemistry, Analytical)Parajuli, D.; Hirota, Koichi; Inoue, Katsutoshi*
Industrial & Engineering Chemistry Research, 48(23), p.10163 - 10168, 2009/11
Times Cited Count：26 Percentile：62.06(Engineering, Chemical)A quaternary amine type sorbent has been prepared by the immobilization of trimethylamine group onto the crosslinked lignophenol matrix. The sorption behavior for a number of metal ions was studied in hydrochloric acid medium. From the batch test of individual metal ion as well as the mixture solution containing equal molar concentration of various metal ions, the sorbent was found to hold selectivity for Au(III), Pd(II), and Pt(IV) ions only with negligible sorption for other metal ions like Cu(II), Co(II), Fe(III), Ni(II), and Zn(II). The sorption kinetics was studied at 303, 323, and 338 K and elucidated the order of sorption of Au(III), Pd(II), and Pt(IV) and from the values of rate constants at different temperatures, the energy of activation has been evaluated. The sorption isotherm study revealed the Langmuir type sorption and from the Langmuir charts the maximum loading capacity of Au(III), Pd(II), and Pt(IV) has been evaluated.
Parajuli, D.; Hirota, Koichi
Journal of Colloid and Interface Science, 338(2), p.371 - 375, 2009/10
Times Cited Count：16 Percentile：37.62(Chemistry, Physical)Parajuli, D.; Khunathai, K.*; Adhikari, C. R.*; Inoue, Katsutoshi*; Oto, Keisuke*; Kawakita, Hidetaka*; Funaoka, Masamitsu*; Hirota, Koichi
Minerals Engineering, 22(13), p.1173 - 1178, 2009/10
Times Cited Count：44 Percentile：88.07(Engineering, Chemical)Parajuli, D.; Hirota, Koichi
ChemSusChem, 2(10), p.965 - 967, 2009/09
Times Cited Count：2 Percentile：13.31(Chemistry, Multidisciplinary)Parajuli, D.; Hirota, Koichi
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Hirota, Koichi; Parajuli, D.
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no abstracts in English
Parajuli, D.; Hirota, Koichi
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The adsorption ability for precious metals was examined for crosslinked lignophenol functionalized with quarternary amine by EB irradiation. The results showed that the functionalized lignophenol could adsorbed more than 90% of Au, Pd, and Pt in acidic solutions of 0
pH5. No adsorption was observed for Fe, Ni Zn, Cu, and Co. It was found that 1kG of the functionalized lignophenol could adsorb 4.0 mol Au, 3.8 mol Pt, and 2.0 mol Pd.
Hirota, Koichi; Parajuli, D.
no journal, ,
no abstracts in English
Parajuli, D.; Hirota, Koichi
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Parajuli, D.; Hirota, Koichi
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Hirota, Koichi; Parajuli, D.
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no abstracts in English
Parajuli, D.; Hirota, Koichi
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Hirota, Koichi; Parajuli, D.; Seko, Noriaki
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Lignin in Japanese cedar wood powder was extracted in the form of lignophenol and was modified with ethylenediamine and trimethylamine groups using Electron-beam technology. The functionalized lignophenol adsorbents were then studied for the recovery of precious metals: Au, Pt, and Pd from urban mine. From the batch test of mixture solution containing equal molar concentration of various metal ions, the sorbent was found to hold selectivity for Au(III), Pd(II), and Pt(IV) ions only with negligible sorption for other metal ions like Cu(II), Co(II), Fe(III), Ni(II), and Zn(II). The biomass sorbent is expected to be an excellent material for recovering the precious metal from urban mine.
Parajuli, D.; Hirota, Koichi; Seko, Noriaki
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Hirota, Koichi; Parajuli, D.; Seko, Noriaki
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High level radioactive waste contains precious metals like Pd, Rh, and Ru. Biomass sorbents were synthesized using Japanese cedar wood and tested its adsorption performance. The results showed that the sorbents functionalize with thioamide group exhibit high adsorption ability for Pd(II) under 
-ray irradiation.
Parajuli, D.; Hirota, Koichi; Seko, Noriaki
no journal, ,
Wood derived lignin was modified with ethylenediamine after electron beam irradiation and its performance for the recovery of precious metals was compared to that modified by chemicals. The results showed that the sorbents obtained by the irradiation had higher sorption ability for precious metals. Electron beam has an advantage for creating high performance biomass absorbents for precious metals such as Au, Pt, and Pd.
Hirota, Koichi; Parajuli, D.; Seko, Noriaki
no journal, ,
Wood derived lignin has been modified with ethylenediamine (EN-CLP) after electron beam irradiation and its performance for the recovery of precious metals has been studied and the results are compared with that of chemically modified derivative. The maximum adsorption capacities of both the adsorbents for Au(III), Pd(II), and Pt(IV) were evaluated as: EN-CLP(EB) 3.1, 2.3, 0.85 mol/kg, and EN-CLP (Chem) 2.4, 1.4, 0.42 mol/kg, respectively. The EN-CLP synthesized by an electron beam has higher capacity for the recovery of the precious metals.
