Godelitsas Athanasios, Astilleros Jose Manuel, Hallam Keith, Harissopoulos Sotirios, Putnis Andrew
Institut für Mineralogie, Universität Münster, Corrensstrasse 24, D-48149 Münster, Germany.
Environ Sci Technol. 2003 Aug 1;37(15):3351-60. doi: 10.1021/es020238i.
Pure calcium carbonate (calcite and aragonite) solid materials of different particle size (100-200 microm fragments and millimeter-sized single crystals) were interacted with Pb in aqueous solutions at room temperature under atmospheric PCO2. In the case of the micrometer-sized samples, the macroscopic investigation using a batch-type treatment procedure (solutions between 10 and 1000 mg/L Pb) and ICP-AES, SEM-EDS, and powder-XRD showed that the metal is readily removed from the aqueous media by both materials and indicated the sorption processes (mainly surface precipitation leading to overgrowth of cerussite and hydrocerussite crystals) taking place in parallel with surface dissolution processes. The various processes occurring at the calcium carbonate solid-water interface were clearly distinguished and defined in the case of the millimeter-sized samples interacted with 1000 mg/L Pb using a combination of wet-chemical, in-situ (AFM) and ex-situ (AFM, SEM) microscopic, and surface spectroscopic (XPS, 12C-RBS) techniques. The in-situ AFM data revealed the dissolution processes on the surface of the calcium carbonates and the simultaneous heterogeneous nucleation of lead carbonate phases and confirmed the secondary dissolution of lead carbonate crystals grown epitaxially from the initial nuclei. The XPS spectra confirmed that adsorption of Pb occurs simultaneously to dissolution at short interaction times (less than approximately 10 min, prior to precipitation-nucleation/crystal growth) in the case of both CaCO3 polymorphs and that the calcite surface with adsorbed Pb may have an aragonite-type character. The 12C-RBS spectra indicated that absorption (incorporation of Pb2+ ions) also takes place in parallel at the surface layers of the calcium carbonates, resulting in formation of solid solutions.
在大气PCO₂条件下，室温时将不同粒径（100 - 200微米碎片和毫米级单晶）的纯碳酸钙（方解石和文石）固体材料与水溶液中的铅进行相互作用。对于微米级样品，采用间歇式处理程序（溶液中铅含量为10至1000 mg/L）以及电感耦合等离子体发射光谱法（ICP - AES）、扫描电子显微镜 - 能谱仪（SEM - EDS）和粉末X射线衍射仪（powder - XRD）进行宏观研究，结果表明两种材料都能轻易地从水介质中去除金属，并显示出吸附过程（主要是表面沉淀导致白铅矿和羟氯铅矿晶体过度生长）与表面溶解过程同时发生。对于与1000 mg/L铅相互作用的毫米级样品，通过结合湿化学、原位（原子力显微镜，AFM）和异位（AFM、扫描电子显微镜）显微镜以及表面光谱（X射线光电子能谱，XPS；¹²C - 卢瑟福背散射光谱，¹²C - RBS）技术，清晰地区分和定义了碳酸钙固 - 水界面发生的各种过程。原位AFM数据揭示了碳酸钙表面的溶解过程以及碳酸铅相的同时异质成核，并证实了从初始核外延生长的碳酸铅晶体的二次溶解。XPS光谱证实，在两种碳酸钙多晶型物的情况下，在短相互作用时间（小于约10分钟，在沉淀成核/晶体生长之前），铅的吸附与溶解同时发生，并且吸附铅的方解石表面可能具有文石型特征。¹²C - RBS光谱表明，在碳酸钙表面层也同时发生吸收（Pb²⁺离子的掺入），从而形成固溶体。
