Neptunium adsorption

McGarrah, J.E. (1991) Neptunium adsorption on synthetic amorphous iron oxyhydroxide. 

Girvin, D. C., Ames, L. L., Schwab, A. P. McGaRRAH, J. E. 1991. Neptunium adsorption on synthetic amorphous iron oxyhydroxide. Journal of Colloid and Interface Science, 141, 67-78. 

The neptunium adsorption on the resin was calculated from the measurements of 239Np not adsorbed according to the following equation ... 

Neptunium adsorption on synthetic ammphous iron oxyhydroxide. J. Colloid Interface ScL 141(1), 67—78. 

DelNero, M., Made, B., Bontems, G. Clement, A. 1997. Adsorption of neptunium(V) on hydrargilite. Radiochimica Acta, 76, 219-228. 

Figures 10, 11 and 12 show the results of the contact experiments for the basalt, shale and quartz monzonite samples. The rate of adsorption was rapid during the first two weeks and changed slowly thereafter. In these experiments Pu, Am and Cm exhibited behavior similar to the results obtained in the blank experiments. Uranium showed moderate adsorption ( 50 percent) on the basalt but only slight adsorption (10-20 percent) on the shale and quartz monzonite wafers. Neptunium showed strong adsorption (70-80 percent) on the shale and slight adsorption ( v 10 percent) on the basalt and quartz monzonite.

Inoue, U. and Tochiyama, O. (1977) Determination of the oxidation states of neptunium at tracer concentrations by adsorption on silica gel and barium sulphate./. Inorg. Nucl. Chem., 39, 1443-1447. 

Bertetti F., Pabalan R. T., and Almendarez M. (1998) Studies of neptunium sorption on quartz, cUnoptiloUte, montmoriUo-nite, and alumina. In Adsorption of Metals by Geomedia (ed. E. Jenne). Academic Press, San Diego, CA, pp. 131-148. 

The purpose of this study was to investigate the anionic exchange behavior of neptunium(V) in sulfate-sulfuric acid, because neptunium is often present as a contaminant during the separation of other actinides (l ). Sulfuric acid systems are seldom utilized in industrial processes, but are often used as part of a laboratory analytical procedure. Literature on neptunium in HC101, HC1, HC1-HF, and HNO3 is quite complete, but the information on the H2S0l system is sketchy at best. There is one report 2) that neptunium(V) is adsorbed strongly on Dowex 2 resin from 0.1 IT to 1 IT H SOip Our measurements indicate that there is very little adsorption of Np(V) on Dowex 1 resin even at low concentrations of sulfate-sulfuric acid. We believe the differences in chemical structure of the two resins are not sufficient to explain the disparity in adsorption. 

The most significant difference between Dowex 1 and Dowex 2 resin is in the order of selectivity of the hydroxide ion. All other mechanical variables between the two resins, such as pore size, shrinkage, capacity and water content, are negligible dif-erences. We conclude that these differences are insufficient to explain the disparity of adsorption of neptunium. 

Figure 1335 Apparent K i values for Np(V) as a function of Eh with INp = 10 M. Sorbent sediments contained quartz, K-feldspar, plagioclase feldspar, kaolinite, muscovite, calcite, chlorite, and dolomite. Apparent Kj values from >10 to > lO, measured for Eh values below about 250 mV, reflect precipitation of Np(IV) solids rather than adsorption. Modified after Lieser and Mohlenweg, Neptunium in the hydrosphere and in the geosphere. Radiochim. Acta 43 27-35. Copyright 1988 by Oldenbourg Verlag GmbH. Used by permission.

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