Interactions of divalent cations with pyrite and mackinawite in seawater and NaCl solutions /
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| Other Authors: | , , , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1988.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | The interactions between the iron sulfide minerals pyrite (FeS2) and mackinawite (FeS), and the divalent cations Ca, Mn, Co, Ni, Cd, and Zn were studied in seawater and NaCl solutions. Cation uptake by the minerals was studied as a function of solution pH, ionic strength and cation concentration. Results were interpreted using a surface complexation model for adsorption or as replacement reactions. Also, the kinetics of adsorption were studied. The surface charge of pyrite was not determined due to the complex kinetic behavior of its reaction with base. Apparent constants for the adsorption of the metals onto pyrite decreased in the order Co > Cd > Mn > Ni > Ca > Zn. No correlation was observed between the apparent adsorption constants and the first hydrolysis constants of the metals or the solubility products of their most soluble sulfide minerals. The apparent adsorption constants for all of the metals onto pyrite were relatively constant between pH 4 and 9, and no trend was observed in the apparent adsorption constants of Co2+, Ni2+, Zn2+ and Cd2+ between approximately 0.01 and 0.7 M NaCl. However, the apparent adsorption constants of Ca2+ and Mn2+ decreased with increasing ionic strength. The apparent adsorption constant of Ca2+ decreased with increasing pyrite surface saturation, while those of Co2+ and Ni2+ were unaffected. The adsorption behavior of Co2+, Ni2+ and Cd2+ in seawater of salinity 35 [ppt] was similar to that observed in 0.7 M NaCl. The rate constants for the adsorption of Co2+, Ni2+ and Zn2+ onto pyrite varied as a function of pH, ionic strength and surface saturation. Interactions between Co2+, Ni2+ and Zn2+, and mackinawite were consistent with a replacement reaction removal mechanism. Initially the removal of metal from solution was log-linear with time, followed by a square root-linear region. The first region was inhibited by increasing ionic strength, while the second region was not. The reaction rate was not sensitive to pH between pH 5.5 and 7.1. The uptake rate of the first region was almost directly proportional to the initial metal concentration. The uptake of Ni2+ in seawater was similar to that observed in 0.1 M NaCl. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Oceanography." |
| Physical Description: | xiv, 198 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |