He Jianyong, Zhang Hongliang, Yue Tong, Sun Wei, Hu Yuehua, Zhang Chenyang
Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan 410083, China.
Key Laboratory of Hunan Province for Comprehensive Utilization of Complex Copper-Lead Zinc Associated Metal Resources, Hunan Research Institute for Nonferrous Metals, Changsha 410100, China.
Langmuir. 2021 Feb 16;37(6):2205-2212. doi: 10.1021/acs.langmuir.0c03575. Epub 2021 Feb 2.
The strategy of enhancing the surface activity by preadsorption of metal ions (surface activation) is an effective way to promote the adsorption of surfactant on surfaces, which is very important in surface process engineering. However, the adsorption mechanism of surfactant (collector) on the surface preadsorbed by metal ions in the explicit solution phase is still poorly understood. Herein, the effects of hydration on the adsorption of benzohydroxamic acid (BHA) onto the oxide mineral surface before and after lead-ion activation are investigated by first-principles calculations, owing to its importance in the field of flotation. The results show that the direct adsorption of BHA on the hydrated surface is not thermodynamically allowed in the absence of metal ions. However, the adsorption of BHA onto the lead-ion-activated surface possesses a very low barrier and a very negative reaction energy difference, indicating that the adsorption of BHA on hydrated Pb at cassiterite surface is very favorable in both thermodynamics and kinetics. In addition, the adsorption of BHA results in the dehydration of hydrated Pb. More interestingly, the surface hydroxyl groups could participate in and may promote the coordination adsorption through proton transfer. This work sheds some new lights on understanding the roles of interfacial water and the mechanisms of metal-ion surface activation.
通过金属离子预吸附来增强表面活性（表面活化）的策略是促进表面活性剂在表面吸附的有效方法，这在表面过程工程中非常重要。然而，在明确的溶液相中，表面活性剂（捕收剂）在金属离子预吸附表面上的吸附机制仍知之甚少。在此，由于其在浮选领域的重要性，通过第一性原理计算研究了水合作用对苯甲羟肟酸（BHA）在铅离子活化前后在氧化物矿物表面吸附的影响。结果表明，在没有金属离子的情况下，BHA在水合表面上的直接吸附在热力学上是不允许的。然而，BHA在铅离子活化表面上的吸附具有非常低的势垒和非常负的反应能量差，这表明BHA在锡石表面水合铅上的吸附在热力学和动力学上都是非常有利的。此外，BHA的吸附导致水合铅脱水。更有趣的是，表面羟基可以通过质子转移参与并可能促进配位吸附。这项工作为理解界面水的作用和金属离子表面活化机制提供了一些新的线索。
