Dunn K, Daniel E, Shuler PJ, Chen HJ, Tang Y, Yen TF
Department of Civil and Environmental Engineering, University of Southern California, Los Angeles, California, 90089-2531
J Colloid Interface Sci. 1999 Jun 15;214(2):427-437. doi: 10.1006/jcis.1999.6224.
Barite (BaSO4) was synthesized at normal pressure and room temperature by mixing sodium sulfate and barium chloride solutions by gentle flow (0.5 ml/min.). The well-formed rectangular and rhombohedral crystals with smooth faces formed from solutions with low degrees of supersaturation. Most precipitates became single crystals. We employed the scanning electron microscope (SEM) to observe barite dissolution by chemical agent diethylenetrinitrilopentaacetic acid. Molecular modeling was used to assist the interpretation of the surface reaction. A kinetic model for the pit growth (initial dissolution) on the surface was evaluated. With SEM microanalysis of barite and kinetic model of pit growth, important surface phenomena and mechanisms of dissolution can be hypothesized. Surface phenomena and composition are very important in barite dissolution. Experimental results suggest that the initial dissolution starts on the two lowest energy surfaces: (001) and (210), and that the etch pits are elongated in one direction on the (210) surface and formed cavities on the (001) surface. The simulated surface structures by molecular modeling can aid the interpretation the pit formation on those selected surfaces. Copyright 1999 Academic Press.
通过以0.5毫升/分钟的平缓流速混合硫酸钠溶液和氯化钡溶液，在常压和室温下合成了重晶石（BaSO₄）。从低过饱和度溶液中形成了具有光滑表面的规则矩形和菱面体晶体。大多数沉淀物变成了单晶。我们使用扫描电子显微镜（SEM）来观察化学试剂二乙烯三胺五乙酸对重晶石的溶解情况。利用分子模型辅助解释表面反应。评估了表面凹坑生长（初始溶解）的动力学模型。通过重晶石的SEM微观分析和凹坑生长动力学模型，可以推测出重要的表面现象和溶解机制。表面现象和组成在重晶石溶解中非常重要。实验结果表明，初始溶解始于两个能量最低的表面：（001）和（210），并且在（210）表面上蚀刻凹坑沿一个方向拉长，在（001）表面上形成空洞。通过分子模型模拟的表面结构有助于解释在那些选定表面上的凹坑形成。版权所有1999年学术出版社。
