Scanning Tunneling Microscopy Studies of Galena: The Mechanisms of Oxidation in Aqueous Solution
Scanning Tunneling Microscopy Studies of Galena: The Mechanisms of Oxidation in Aqueous Solution
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DOI：
10.1021/la00007a039
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发表时间：
1995-07
期刊：
影响因子：
3.9
通讯作者：
B. Kim;R. Hayes;C. Prestidge;J. Ralston;R. Smart
中科院分区：
文献类型：
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作者：
B. Kim;R. Hayes;C. Prestidge;J. Ralston;R. Smart
利用扫描隧道显微镜（STM）研究了方铅矿（PbS）在水溶液中的表面形貌。研究了pH值和吹扫气体种类对方铅矿表面溶解和氧化过程的影响。方铅矿表面的STM形貌成像显示，随着反应时间的增加，亚纳米凹坑的发展。互补原子力显微镜（AFM）成像证实了这种行为。这些坑的深度（z-尺寸）直接对应于方铅矿的晶胞尺寸（0.3或0.6 nm），并表明发生的主要表面过程是一致的溶解，这已被证实的X射线光电子能谱研究。这些凹坑的x x，y尺寸及其形成速率在很大程度上取决于pH值和所使用的吹扫气体类型。铅2+离子的引入导致在方铅矿表面的氢氧化铅胶体的形成;明显的方向性是显而易见的。在浮选分离的背景下提出并讨论了方铅矿在水溶液中表面化学反应初始阶段的机理。
A scanning tunneling microscope (STM) was used to study the surfaces of galena (PbS) in aqueous solution. The influences of pH and type of purging gas on the dissolution and oxidation processes at galena surfaces were investigated. STM topographical imaging of the galena surfaces showed the development of sub-nanometer pits with increasing reaction time. Complementary atomic force microscopy (AFM) imaging confirmed the behavior. The depths (z-dimensions) of these pits correspond directly to the unit cell dimensions of galena (0.3 or 0.6 nm) and suggest that the main surface process occurring is congruent dissolution ; this has been confirmed by X-ray photoelectron spectroscopy studies. The x x,y -dimensions of these pits and the rate of their formation depended strongly on the pH and the type of purging gas used. Introduction of Pb 2+ ions resulted in the formation of lead hydroxide colloids at the galena surface ; distinct directionality is evident. Mechanisms for the initial stages of the surface chemical reactions of galena in aqueous solution are proposed and discussed in the context of flotation separation.