Montmorillonitin Radyoaktif bir madde olan Uranyumu Bağlayabilme Özelliği
Amerika Enerji Departmanı tarafından yayınlanan bir makalede, Montmorillonitin, Suda ayrıştırılmış Uranyum formunu bağlama özellikleri, etkileri ve reaksiyonları incelenmiş ve çalışma sonunda,
Çeşitli şart ve ortam koşullarına bağlı olarak, Montmorillonitin Uranyumun bu formunu bağlama kapasitesi konusunda önemli verilere ulaşılmıştır.
Bu akademik çalışmanın İngilizce özeti aşağıdadır.
The Influence Of Uranyl Hydrolysis And Multiple Site-Reactions On Adsorption Of U(vı) To Montmorillonite
James P. Mckınley, John M. Zachara, Steven C. Smıth, And Gary D. Turner
Pacific Northwest Laboratory, MSIN K3-61, P.O. Box 999, Richland, Washington, USA
Clays and Clay Minerals, Vol. 43, No. 5, 586-598, 1995
Abstract: Adsorption of uranyl to SWy- 1 montmorillonite was evaluated experimentally and results were modeled to identify likely surface complexation reactions responsible for removal of uranyl from solution. Uranyl was contacted with SWy- 1 montmorillonite in a NaC104 electrolyte solution at three ionic strengths (I = 0.001, 0.01, 0.1), at pH 4 to 8.5, in a N2~) atmosphere. At low ionic strength, adsorption decreased from 95% at pH 4 to 75% at pH 6.8. At higher ionic strength, adsorption increased with pH from initial values less than 75%; adsorption edges for all ionic strengths coalesced above a pH of 7. A site-binding model was applied that treated SWy-1 as an aggregate of fixed-charge sites and edge sites analogous to gibbsite and silica. The concentration of fixed-charge sites was estimated as the cation exchange capacity, and non-preference exchange was assumed in calculating the contribution of fixed-charge sites to total uranyl adsorption. The concentration of edge sites was estimated by image analysis of transmission electron photomicrographs. Adsorption constants for uranyl binding to gibbsite and silica were determined by fitting to experimental data, and these adsorption constants were then used to simulate SWy-1 adsorption results. The best simulations were obtained with an ionization model in which A1OH2 + was the dominant aluminol surface species throughout the experimental range in pH. The pH-dependent aqueous speciation of uranyl was an important factor determining the magnitude of uranyl adsorption. At low ionic strength and low pH, adsorption by fixed-charge sites was predominant. The decrease in adsorption with increasing pH was caused by the formation of monovalent aqueous uranyl species, which were weakly bound to fixed-charge sites. At higher ionic strengths, competition with Na+ decreased the adsorption of Uoz 2+ to fixed-charge sites. At higher pH, the most significant adsorption reactions were the binding of UP22+ to A1OH and of( UO2)3(OH)5 + to SiOH edge sites. Near-saturation of A1OH sites by UOz 1+ allowed significant contributions of SiOH sites to uranyl adsorption.
Montmorillonitin Radyoaktif bir madde olan Uranyumu Bağlayabilme Özelliği
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