A surface characterization of priority metal pollutants in Portland cement /
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| Other Authors: | , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | The characterization of pozzolanic materials, with and without hazardous wastes, is a very complex problem, which requires application of the most modern analytical methods. Since the binding of many of the waste materials is expected to be associated with the surface of the hydrated cementitous material, surface analytical techniques are required as well as conventional bulk techniques. X-ray photoelectron spectroscopy (XPS), a surface sensitive technique, is employed in the elucidation of chemical information regarding the environment of the priority metal pollutants; lead, chromium, zinc, cadmium, mercury and barium solidified in Portland cement. Ion scattering spectroscopy (ISS) is applied in the determination of surface species of the top few monolayers. Samples were prepared using Type 1 Portland Cement. The metals were added as the aqueous solution of the nitrate salts [Hg(NO3)2, Pb(NO3)2, Zn(NO3)2, Cd(NO3)2, Cr(NO3)3 and Ba(NO3(2] as 10% and 20% by weight nitrate. Standards were prepared with cation free water. The locations of metal ions, with respect to the bulk and surface of the cement matrix as a function of the interfacial phenomena of the alkaline medium were probed. Bulk and topographical examinations were carried out using energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) respectively. Preferential bulk locations of chromium compared to high concentrations of surface lead species have been identified. Zinc, cadmium and mercury are thought to exhibit similar chemistries in the highly buffered alkaline medium but their final solidification products seem to differ in how they are contained in the matrix. Isolated deposits of mercuric oxide within the cement matrix have been found. Large deposits of calcium rich areas are common for barium doped cement. Evidence for the formation of barium sulfate and carbonate exists. All cation doped cements show tremendous increases in surface carbonate content. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Chemistry." |
| Physical Description: | xii, 176 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |