Effect of citric acid on uranyl(VI) solution speciation, gas-phase chemistry and surface interactions with alumina
- 出版日期：2004.
- 页数：1 v. :
- 第一责任说明：Sofie Portia Pasilis.
- 分类号：a484 ; a875
- ISBN：0496906887(ebk.) :
MARC全文
02h0029994 20120629093740.0 cr un||||||||| 120628s2004 xx ||||f|||d||||||||eng | 3158135 0496906887(ebk.) : CNY371.35 NGL NGL NGL a484 ; a875 Pasilis, Sofie Portia. Effect of citric acid on uranyl(VI) solution speciation, gas-phase chemistry and surface interactions with alumina [electronic resource] / Sofie Portia Pasilis. 2004. 1 v. : digital, PDF file. Adviser: Pemberton, Jeanne E. Thesis (Ph.D.)--The University of Arizona, 2004. Activities related to nuclear weapons production have left a legacy of uranium contamination in the United States. Understanding the chemical interactions that uranium undergoes in the environment is important for prediction of uranium mobility and development of remediation strategies. A detailed spectroscopic examination of the pH-dependent behavior of the UO22＋-citrate system in aqueous solution was completed using Raman, ATR-FTIR, and NMR spectroscopies, combined with ESI-MS. Three structurally-distinct UO22＋-citrate complexes, {UO2)2Cit2}2-, {UO 2)3Cit3}3-, and UO 2)3Cit2 exist in dynamic equilibrium over a pH range from 2 to 9. 17O and 13C NMR data confirm the previously published structure of {UO2)2Cit 2}2- and indicate that {UO2)3 Cit3}3- is a symmetric, fluxional molecule. The UO2)3Cit2 complex was found to have a rigid structure and two structural isomers. Chemical interactions of UVI), citric acid and Al2O 3 were investigated using ATR-FTIR spectroscopy to examine how complexation of UVI) by citrate affects adsorption of UVI) to Al2O3. Participation in UO22＋-citrate complexes does not significantly affect the ability of citrate to chemisorb to Al2O 3. The UO22＋-citrate complexes dissociate upon adsorption, with hydrolysis of UO22＋. Adsorption isotherms developed from ATR-FTIR data indicate enhanced citrate adsorption to Al2O3 in the presence of UO22＋ , suggesting that UO22＋ acts as a central link between two citrate ligands, one of which is complexed to Al2O 3. UO22＋-citrate complexes can physisorb to citrate-saturated Al2O3. This study demonstrates how an in-depth infrared spectroscopic analysis of UO22＋-ligand complexes both in solution and adsorbed to oxide surfaces can be used to understand the adsorption mechanisms of these complexes. ESI-MS was investigated for the characterization of UVI) species in groundwater. Both ion trap and FTICR instruments were used. UO2 2＋ forms complexes with ligands such as acetate, trifluoroacetate, and nitrate, which readily react with CH3CN, CH3OH, and H2O to form solvated gas-phase species of the form [UO 2L)Sn]＋, where L represents the ligand, S represents solvent, and 1 &le； n &le； 4. n is directly related to the number of available coordination sites on UO22＋, providing insight into the coordination environment of UO22＋. Solvent exchange and addition reactions readily occur. UO2 2＋ also forms coordinately saturated negatively-charged complexes with nitrate. UO22＋-carbonate complexes were also investigated. Uranium mines and mining ; Environmental geochemistry. Waste disposal. Electronic dissertations. aeBook. aCN bNGL http://pqdt.bjzhongke.com.cn/Detail.aspx?pid=3FRkuzSmrGI%3d NGL Bs1633 rCNY371.35 ; h1 bs1204