<p>Alcacio, Tim. The Molecular Scale Nature of Copper(II) and Arsenate Bonding With Goethite-Humate Complexes. In soils, interactions between clay minerals and natural organic matter are known to affect the cycling of heavy metals and anions. Contaminant structures at mineral surfaces that contain adsorbed organic matter will have a significant influence on the bioavailability of the contaminant. The structure of copper(II) and arsenate complexes on goethite in the presence and absence of adsorbed humic acid were studied with extended x-ray absorption fine structure (EXAFS) spectroscopy and with x-ray absorption near edge structure (XANES) spectroscopy. The copper(II) and arsenate formed edge shared inner-sphere surface complexes with goethite. The copper(II) itself was present in a distorted octahedral configuration, and ternary complexes involving bonding with both the humic acid and the goethite (Type A complexes) or adsorbed humic acid (Type B complexes), occurred at pH 5.6. At pH 8, the copper(II) was found to display a stronger affinity for the goethite surface and the formation of ternary complexes did not occur. The EXAFS analyses demonstrated that arsenate was present in a tetrahedral configuration and was predominantly bonded to goethite surface sites. Regardless of the level of adsorbed humic acid, the arsenic coordination environment was similar and indicated that ternary complexes could not be distinguished. <P>
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-20010113-190843 |
| Date | 22 January 2001 |
| Creators | Alcacio, Tim |
| Contributors | Dr. Dean Hesterberg, Dr. Dale Sayers, Dr. Robarge, Dr. Jim Martin |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-20010113-190843 |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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