Department of Soil Science and Agricultural Chemistry, University of Santiago de Compostela, Santiago de Compostela, Spain.
J Colloid Interface Sci. 2012 Nov 15;386(1):338-43. doi: 10.1016/j.jcis.2012.07.008. Epub 2012 Jul 20.
The presence of iron oxides may play an important role in controlling the mobility and availability of contaminants in soils and waters affected by acid mine drainage. The present study describes the uptake of arsenate, chromate and molybdate from solution by synthetic schwertmannite. Batch experiments were performed at different pH values in order to obtain the adsorption isotherms for the three oxyanions. In addition to the formation of surface complexes between the oxyanions and the iron surface reactive groups, it is also expected that anion exchange will occur between sulphate anions from the schwertmannite structure and the oxyanions present in the solid/solution interface. Comparison of the experimental adsorption results for the different oxyanions showed large differences, not only the amount adsorbed, which was much higher for arsenate, but also in the sulphate exchange with the anions in solution. In case of chromate, the main mechanism of adsorption process is the exchange reaction with the sulphate groups present in the schwertmannite. The observed results suggest a different adsorption mechanisms for each of the three oxyanions, with important implications for the mobility of these anions in acid mine drainage systems.
氧化铁的存在可能在控制受酸性矿山排水影响的土壤和水中污染物的迁移性和可用性方面发挥重要作用。本研究描述了合成水针铁矿从溶液中摄取砷酸盐、铬酸盐和钼酸盐的情况。在不同 pH 值下进行了分批实验，以获得三种含氧阴离子的吸附等温线。除了含氧阴离子与铁表面反应基团之间形成表面络合物之外，还预计在水针铁矿结构中的硫酸盐阴离子与固/液界面上存在的含氧阴离子之间将发生阴离子交换。不同含氧阴离子的实验吸附结果的比较表明存在很大差异，不仅吸附量（砷酸盐的吸附量要高得多），而且与溶液中阴离子的硫酸盐交换也存在差异。对于铬酸盐，吸附过程的主要机制是与水针铁矿中存在的硫酸盐基团进行交换反应。观察到的结果表明，对于这三种含氧阴离子中的每一种，都存在不同的吸附机制，这对这些阴离子在酸性矿山排水系统中的迁移性有重要影响。
