Stuies of neptunium(V) sorption on montmorillonite, clinoptilolite, quartz and {alpha}-alumina
- Southwest Research Institute, San Antonio, TX (United States)
{sup 237}Np is a particular concern to the safety suitability of Yucca Mountain, Nevada, as a geologic repository for high-level nuclear wastes. In this study, montmorillonite, clinoptilolite, quartz, and {alpha}-alumina were reacted with {sup 237}Np-bearing solutions to characterize the sorption behavior of Np(V) on these minerals. Batch experiments were conducted at room temperature (20{plus_minus}2{degrees}C) over a range of conditions in which solution pH, sorbent surface area, initial concentration of N(V), ionic strength, and partial pressure of CO{sub 2} were varied. For all the minerals studied, Np(V) sorption begins at pH values coincident with the start of Np hydrolysis in solution ({approximately}6.5-7). For solutions undersaturated with respect to atmospheric CO{sub 2}, sorption increases continuously with increasing pH. For solutions at equilibrium with atmospheric CO{sub 2}, the {open_quotes}sorption envelope{close_quotes} is coincident with the calculated predominance field (pH {approximately}7-9.5) of the NpO{sub 2}(OH){sup 0}(aq) species, and sorption is inhibited at higher pH where neptunyl carbonate complexes predominate. Modeling of the sorption behavior of Np(V) was performed using a surface complexation-approach (Diffuse-Layer Model).
- OSTI ID:
- 370467
- Report Number(s):
- CONF-960376-; TRN: 96:003805-0519
- Resource Relation:
- Conference: Spring national meeting of the American Chemical Society (ACS), New Orleans, LA (United States), 24-28 Mar 1996; Other Information: PBD: 1996; Related Information: Is Part Of 211th ACS national meeting; PB: 2284 p.
- Country of Publication:
- United States
- Language:
- English
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