Forryan Claire L, Klymenko Oleksiy V, Brennan Colin M, Compton Richard G
Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom.
J Phys Chem B. 2005 Feb 24;109(7):2862-72. doi: 10.1021/jp040508e.
We present a mathematical model for the surface-controlled dissolution of solid particles. This is applied to the dissolution of a solid having different particle size distribution functions: those of a monodispersed solid containing particles of all one size, a two-size-particle distribution, and a Gaussian distribution of the particle sizes. The dissolution of potassium bicarbonate in dimethylformamide is experimentally studied indirectly at elevated temperatures. We monitor the dissolution via the homogeneous deprotonation of 2-cyanophenol by dissolved KHCO3. The loss of 2-cyanophenol was detected electrochemically at a platinum microdisk electrode, and separately, the formation of the 2-cyanophenolate anion was monitored via UV-visible spectroscopic analysis. The results presented show that the kinetics of the loss of 2-cyanophenol behaves on one hand as a homogeneous chemical process and on the other hand as a dissolution-rate-controlled process. Initially, predissolved KHCO3 in solution deprotonates the 2-cyanophenol and homogeneous reaction dominates the observed kinetics, and at longer times, the observed kinetics is controlled by the rate of KHCO3 dissolution. Modeling of the experimental results for the surface-controlled dissolution of KHCO3 in dimethylformamide (DMF) yielded a mean value for the dissolution rate constant, k, at elevated temperatures; k was found to have a value of (1.1 +/- 0.3) x 10(-8) mol cm(-2) s(-1) at 100 degrees C, and the activation energy for the dissolution was 34.4 +/- 0.4 kJ mol(-1) over the temperature range 60-100 degrees C.
我们提出了一个用于固体颗粒表面控制溶解的数学模型。该模型应用于具有不同粒度分布函数的固体溶解情况：单一尺寸颗粒的单分散固体、两种尺寸颗粒分布以及粒度的高斯分布。在升高的温度下，对碳酸氢钾在二甲基甲酰胺中的溶解进行了间接实验研究。我们通过溶解的KHCO₃对2 - 氰基苯酚的均相去质子化来监测溶解过程。在铂微盘电极上通过电化学方法检测2 - 氰基苯酚的损失，并且另外通过紫外 - 可见光谱分析监测2 - 氰基酚酸根阴离子的形成。给出的结果表明，2 - 氰基苯酚损失的动力学一方面表现为均相化学过程，另一方面表现为溶解速率控制过程。最初，溶液中预溶解的KHCO₃使2 - 氰基苯酚去质子化，均相反应主导了观察到的动力学，而在较长时间后，观察到的动力学由KHCO₃的溶解速率控制。对KHCO₃在二甲基甲酰胺（DMF）中表面控制溶解的实验结果进行建模，得到了升高温度下溶解速率常数k的平均值；在100℃时，发现k的值为(1.1±0.3)×10⁻⁸ mol cm⁻² s⁻¹，在60 - 100℃的温度范围内，溶解的活化能为34.4±0.4 kJ mol⁻¹。
