The dissolution kinetics of feldspars at 25°C and 1 atm CO2 partial pressure
The dissolution kinetics of feldspars at 25°C and 1 atm CO2 partial pressure
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DOI：
10.1016/0016-7037(76)90192-7
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发表时间：
1976
影响因子：
5
通讯作者：
E. Busenberg;C. Clemency
中科院分区：
文献类型：
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作者：
E. Busenberg;C. Clemency
本文研究了两种钾长石和六种斜长石的5%悬浮液在1atmPCO_2下400-1200小时的溶解动力学。小于37 μm的颗粒的比表面积为0.83 - 1.84m_2/g。在频繁的间隔下，在对溶液取样时在反应池中测量搅拌的悬浮液的pH。对过滤后的水样进行酸化处理，然后分析Si、Al、K、Na、Ca、Mg和Fe。(1)持续约1分钟的初始离子交换阶段，在此期间表面阳离子被本体溶液中的氢离子取代，2. (2)长达4天的非抛物线阶段，其特征在于阳离子和柠檬酸非常快速地释放到本体溶液中，3. (3)扩散控制的抛物线阶段，持续约19天，4. (4)一个稳定状态阶段，其特征在于阳离子和草酸的非常缓慢的释放。在pH值约为5.5的条件下，计算了所有菱沸石的速率常数。计算的抛物线速率常数范围为3.4 × 10 - 14 ~ 9.3 × 10 - 13 mole/cm ~ 2/sec ~（1/2），线性速率常数范围为3.2 × 10 - 17 ~ 2.5 × 10 - 15 mole/cm ~ 2/sec，表观扩散系数为1 × 10 - 22 ~ 5 × 10 - 21 cm ~ 2/sec。所有斜长石表层的硅铝分子比为1：1，而钾长石的硅铝分子比为2：1。
The dissolution kinetics of 5% by weight suspensions of two potassium feldspars and six plagioclases were studied for 400–1200 hr at 1 atmPCO2The less than 37 μm particles had surface areas ranging from 0.83 to 1.84 m2/g. At frequent intervals, the pH of the stirred suspensions were measured in the reaction cell as the solutions were sampled. The filtered aqueous samples were acidified and then were analyzed for Si, Al, K, Na, Ca, Mg, and Fe.The following sequence of events were recognized in the artificial weathering of all the feldspars:1.(1) an initial ion exchange stage lasting approximately l min during which the surface cations were replaced by hydrogen ions from the bulk solution,2.(2) an up to 4 day non-parabolic stage characterized by the very rapid release of cations and silicic acid into the bulk solution,3.(3) a diffusion-controlled parabolic stage lasting approximately 19 days, and4.(4) a steady-state stage characterized by the very slow release of cations and silicic acid. All the rate constants for all the feldspars were evaluated at the pH of about5.5. The calculated parabolic rate constants range from 3.4 × 10−14to 9.3 × 10−13mole/cm2/sec1/2, the linear rate constants range from 3.2 × 10−17to 2.5 × 10−15mole/cm2/sec, and the apparent diffusion coefficients range from 1 × 10−22to 5 × 10−21cm2/sec.The steady-state composition of the surface layer of all the plagioclases appears to have a 1:1 Si: Al molecular ratio, whereas in contrast, the potassium feldspars appear to have a 2:1 ratio.