Characterization of surface mediated plutonium oxidation state transformations by synthetic iron and manganese (oxyhydr)oxides
- 出版日期：2004.
- 页数：1 v. :
- 第一责任说明：Brian A. Powell.
- 分类号：a276.1
- ISBN：0496987461(ebk.) :
MARC全文
02h0029998 20120629105309.0 cr un||||||||| 120629s2004 xx ||||f|||d||||||||eng | 3164469 0496987461(ebk.) : CNY371.35 NGL NGL NGL a276.1 Powell, Brian A. Characterization of surface mediated plutonium oxidation state transformations by synthetic iron and manganese (oxyhydr)oxides [electronic resource] / Brian A. Powell. 2004. 1 v. : digital, PDF file. Adviser: Fjeld, Robert A. Thesis (Ph.D.)--Clemson University, 2004. A study was performed to test the hypothesis that the Pu oxidation state in mineral solutions depends on the oxidation state of Fe or Mn in the mineral structure. A series of batch experiments, initially containing either PuIV) or PuV), were used to monitor changes in aqueous and solid phase Pu oxidation state over time in magnetite Fe3O4), hematite alpha-Fe2O3), goethite alpha-FeOOH), hausmannite Mn3O4), manganite gamma-MnOOH), and pyrolusite beta-MnO2) suspensions containing Pu amended 0.01 M NaCl. These minerals were selected because they have a wide range of Fe and Mn oxidation states. Additionally, 30-day pH adsorption edge experiments were performed to monitor the oxidation state distribution of Pu in hausmannite Mn3O4), manganite gamma-MnOOH), and pyrolusite beta-MnO 2) suspensions in the pH range 2 to 8. Reduction of PuV) was observed in all magnetite, hematite, and goethite solutions at pH greater than 3. The overall reaction consisted of both an adsorption step and a reduction step. Adsorption was the rate-limiting step in magnetite and hematite systems. In goethite systems, adsorption was sufficiently rapid that it did not appear to affect the reduction rate. Reduction in these systems is proposed to be promoted by the stability of PuIV) on mineral surfaces, likely as a hydroxide species. Additionally, the rate of PuV) reduction was found to increase when hematite and goethite samples were exposed to fluorescent light. The iron oxyhydr)oxide minerals are semi-conductors. Therefore, electron transfer through conduction bands of the iron oxyhydr)oxide minerals may have facilitated PuV) reduction. PuV) was both oxidized and reduced upon interaction with the manganese oxyhydr)oxide minerals hausmannite, manganese, and pyrolusite. Initially, PuIV), PuV), and PuVI) were all observed on the solid phase. However, over time the fraction of PuIV) on the solid phase increased, with concurrent decreases in the fraction of PuV) and PuVI). Reduction of PuV) was also observed on the surface of glass beads. Batch pH adsorption edge experiments indicated that, after 30 days, PuIV) was the predominant solid phase species but significant fractions of PuV) and PuVI) were observed. The fraction of PuV) and PuVI) increased as the pH increased. However, based upon the results of kinetic experiments, which showed a continually increasing fraction of solid phase PuIV) over time, it is expected that Pu remaining on the solid phase will become PuIV) given sufficient reaction time. Abstract shortened by UMI.) Plutonium. Electronic dissertations. aeBook. aCN bNGL http://pqdt.bjzhongke.com.cn/Detail.aspx?pid=%2fIGnNKiPpmw%3d NGL Bs1637 rCNY371.35 ; h1 bs1204