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An Experimental and Modeling Study of Silicate Dissolution Kinetics Near Equilibrium
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | An Experimental and Modeling Study of Silicate Dissolution Kinetics Near Equilibrium. |
| 개인저자 | Zhang, Yilun. |
| 단체저자명 | Indiana University. Environmental Science. |
| 발행사항 | [S.l.]: Indiana University., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 186 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-03B. Dissertation Abstract International |
| ISBN | 9781085642798 |
| 학위논문주기 | Thesis (Ph.D.)--Indiana University, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-03, Section: B.
Advisor: Zhu, Chen. |
| 이용제한사항 | This item must not be sold to any third party vendors.This item must not be added to any third party search indexes. |
| 요약 | Near-equilibrium dissolution rates of silicate minerals are critical for assessing the safe geological storage of CO2 and high-level nuclear wastes. Therefore, assessing the dissolution behavior of those substances is also of critical importance. As one of the most widely occurring and abundant silicate minerals, feldspars have long been the subject of such dissolution studies. Unfortunately, dissolution behavior at environmentally relevant conditions is still poorly understood due to the difficulties involved in experiments at circumneutral pH and near-equilibrium conditions. These difficulties include secondary phase precipitation and low reaction rates.The isotope doping method is a promising technique which can decouple simultaneous dissolution-precipitation reactions at circumneutral pH and near-equilibrium conditions. My study used this method to analyze the dissolution of albite at 50 째C and pH=5-6. The initial solution was doped with 29Si and solutes were added to set the initial solution at near-equilibrium conditions. The results of my experiments showed that even though the system seemed to be in equilibrium with albite, albite dissolution was coupled to multiple other secondary phase precipitation reactions was, which led to a net change in solution chemistry. Further analysis indicated that this evolution in solution chemistry was consistent with coupled dissolution-precipitation reactions between albite and analcime, or between albite and an analcime-like phase. Furthermore, contrary to the commonly assumed transition state theory (TST) rate equations, my results also suggested that the feldspar precipitation reaction may not occur at a significant level.In addition to my work on albite dissolution, I also conducted experiments on the kinetics of the kyanite dissolution reaction. The results of these experiments showed that the dissolution rate of kyanite can be described by the rate equation (n/a) where the rate constant, k = 5.08x10-13 mol m-2 s-1, and the activation energy, Ea = 73.5 kJ/mol.The dissolution rate of kyanite is pH-independent at near-neutral conditions (pH = 3.5-7.5) and at temperatures between 0 째C and 22 째C. This phenomenon can be attributed to the surface speciation of kyanite, which has a wide pH range under which the neutral surface species (>SOH) dominates. |
| 일반주제명 | Environmental science. |
| 언어 | 영어 |
| 바로가기 | 
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