Hu Wenjihao, Tian Mengjie, Cao Jian, Xie Lei, Gong Lu, Sun Wei, Gao Zhiyong, Zeng Hongbo
Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada.
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083 PR China.
Langmuir. 2020 Jul 21;36(28):8199-8208. doi: 10.1021/acs.langmuir.0c01307. Epub 2020 Jul 9.
Probing the interaction mechanism between organic molecules and material surfaces in the presence of metal ions is of great importance in many fields, such as mineral flotation. The collectability of benzohydroxamic acid (BHA) to a spodumene (LiAl(SiO)) mineral surface during mineral flotation could be enhanced with the addition of metal ion activators-Pb ions. Pb ions could be added as either Pb-BHA complex formed by premixing Pb ions and BHA molecules at a given ratio or sequential addition of Pb ions and BHA molecules. However, the complete understanding of the interaction mechanisms (e.g., adhesion) between BHA and the spodumene mineral surface in the presence of Pb ions remains very limited. In this study, atomic force microscopy (AFM) was used to measure the intermolecular forces between BHA and the spodumene mineral surface in aqueous solutions. A BHA model molecule, that is, -hydroxy-4-mercaptobenzamide (MBHA), was synthesized to prepare a BHA-functionalized AFM probe for force measurements. Two model systems (i.e., a Pb-BHA complex interacting with the spodumene mineral surface (model I) and BHA with a Pb-activated spodumene surface (model II)) were investigated for comparing the role of Pb in BHA-mineral adhesion. The adhesion measured for model I (23.7 mN/m) is much higher than that of model II (12.5 mN/m), as further supported by the adsorption energies obtained from density functional theory (DFT) calculations. The calculation results showed a higher adsorption energy for model I (∼188.58 kJ/mol) than model II (∼128.16 kJ/mol), which is due to the better spodumene flotation recovery for the Pb-BHA complex as a collector than the sequential addition of Pb and BHA. This work provides useful information on the intermolecular interactions between chemical additives and mineral surfaces in complex mineral flotation processes, and the methodology can be readily extended to other related interfacial processes such as membrane technology, water treatment, oil production, and bioengineering processes.
在许多领域，如矿物浮选，探究金属离子存在下有机分子与材料表面之间的相互作用机制具有重要意义。在矿物浮选过程中，添加金属离子活化剂——铅离子，可以增强苯甲羟肟酸（BHA）对锂辉石（LiAl(SiO)）矿物表面的捕收能力。铅离子可以以给定比例预混合铅离子和BHA分子形成的Pb-BHA络合物形式添加，也可以依次添加铅离子和BHA分子。然而，对于铅离子存在下BHA与锂辉石矿物表面之间的相互作用机制（如粘附）的全面理解仍然非常有限。在本研究中，使用原子力显微镜（AFM）测量水溶液中BHA与锂辉石矿物表面之间的分子间力。合成了一种BHA模型分子，即4-巯基苯甲酰胺（MBHA），以制备用于力测量的BHA功能化AFM探针。研究了两个模型系统（即Pb-BHA络合物与锂辉石矿物表面相互作用（模型I）和BHA与铅活化的锂辉石表面相互作用（模型II）），以比较铅在BHA-矿物粘附中的作用。模型I测得的粘附力（23.7 mN/m）远高于模型II（12.5 mN/m），密度泛函理论（DFT）计算得到的吸附能进一步支持了这一点。计算结果表明，模型I的吸附能（约188.58 kJ/mol）高于模型II（约128.16 kJ/mol），这是因为作为捕收剂的Pb-BHA络合物比依次添加铅和BHA具有更好的锂辉石浮选回收率。这项工作为复杂矿物浮选过程中化学添加剂与矿物表面之间的分子间相互作用提供了有用信息，并且该方法可以很容易地扩展到其他相关的界面过程，如膜技术、水处理、石油生产和生物工程过程。
