He Jianyong, Sun Wei, Chen Daixiong, Gao Zhiyong, 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 Mar 23;37(11):3490-3499. doi: 10.1021/acs.langmuir.1c00322. Epub 2021 Mar 12.
Surface coordination chemistry is important in areas such as adsorption, separation, and catalysts. In this work, surface coordination interactions of benzohydroxamic acid (BHA) with the lead ion [Pb(II)] adsorbed on the cassiterite surface have been investigated by first-principles calculations due to its great significance in froth flotation. Cluster calculations show that BHA possesses the weakest chelation with Pb(II) due to the electron withdrawal ability of the benzyl ring in comparison with other hydroxamic acids. Pb(II) thermodynamically prefers to react with the cassiterite surface rather than BHA. On the other hand, the partial density of states and the atomic overlap populations have consistently verified that the adsorption of BHA results in a better symmetry in electron densities than the hydrated Pb(II). The electron density maps and the electronic localization functions have further visualized the rearrangement of the 6s lone pair around the lead atom. It can be concluded that the surface coordination mechanisms of Pb(II) on oxide minerals can be attributed to the coordination ability of BHA and the unique electronic structure of Pb(II), which accounts for the reported better flotation performance of the pre-assemble strategy than the pre-activating approach. This work sheds some new light on the unique coordination activation mechanism of metal ions on oxide mineral surfaces. It should be instructive to design and screen new environment-friendly flotation reagents and flotation flowsheets.
表面配位化学在吸附、分离和催化等领域具有重要意义。在这项工作中，由于苯甲羟肟酸（BHA）在泡沫浮选中具有重要意义，通过第一性原理计算研究了其与吸附在锡石表面的铅离子[Pb(II)]的表面配位相互作用。簇计算表明，与其他羟肟酸相比，由于苄基环的吸电子能力，BHA与Pb(II)的螯合作用最弱。从热力学角度来看，Pb(II)更倾向于与锡石表面反应而非BHA。另一方面，态密度和原子重叠布居一致地证实，BHA的吸附导致电子密度比水合Pb(II)具有更好的对称性。电子密度图和电子定域函数进一步直观展示了铅原子周围6s孤对电子的重排。可以得出结论，Pb(II)在氧化物矿物表面的表面配位机制可归因于BHA的配位能力和Pb(II)独特的电子结构，这解释了报道的预组装策略比预活化方法具有更好的浮选性能。这项工作为金属离子在氧化物矿物表面独特的配位活化机制提供了新的见解。这对于设计和筛选新型环保浮选药剂及浮选流程具有指导意义。
