矿物溶解的表面化学动力学机理

THE MECHANISM OF SURFACE CHEMICAL KINETICS OF DISSOLUTION OF MINERALS

本文应用表面化学理论分析了矿物在水溶液中的溶解反应动力学机理。表面化学的催化作用使矿物溶解反应的活化能显著降低。矿物溶解速率受表面吸附、表面交换反应和解吸反应等表面化学过程的控制并与溶液的pH值有关，正比于溶液αH＋值的nθ次幂。受表面吸附控制时，nθ＝1，溶解速率随pH增大而减小；受表面交换反应控制时，nθ＝0，溶解速率与pH无关；受解吸反应控制时，酸性条件下nθ为0～1内的正小数，碱性条件下nθ为-1～0之内的负小数。大多数矿物的溶解作用在酸性条件下受表面吸附和／或表面交换反应控制，在碱性条件下受解吸反应的控制。

This paper deals with the mechanism of dissolution reaction kinetics of minerals in aqueous solution based on the theory of surface chemistry. Surface chemical catalysis would lead to an obvious decrease in active energy of dissolution reaction of minerals. The dissolution rate of minerals is controlled by surface adsorption and surface exchange reactions and desorption, depends on the pH of the solution and is directly proportional to α. When controlled by surface adsorption, i. e., nθ= 1, the dissolution rate will decrease with increasing pH; when controlled by surface exchange reaction, i. e., nθ= 0, the dissolution rate is independent of pH; when control1ed by desorption, nθis a positive decimal between 0 and 1 in acidic solution and a negative decimal between - 1 and 0 in alkaline solution. Dissolution of many minerals is controlled by surface adsorption and/or surface exchange reactions under acid condition and by desorption under alkaline condition.