Carrasco Naraya, Kretzschmar Ruben, Pesch Marie-Laure, Kraemer Stephan M
Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Sciences, ETH Zurich, CHN, CH-8092 Zurich, Switzerland.
J Colloid Interface Sci. 2008 May 15;321(2):279-87. doi: 10.1016/j.jcis.2008.02.011. Epub 2008 Feb 14.
We investigated the influence of the surfactants sodium dodecyl sulfate (SDS) and rhamnolipid (RhL) on ligand-promoted dissolution of goethite (alpha-FeOOH) and boehmite (gamma-AlOOH) at pH 6. The siderophore desferrioxamine B (DFOB), its derivate desferrioxamine D (DFOD), ethylenediaminetetraacetic acid (EDTA), and 8-hydroxyquinoline-5-sulfonic acid (HQS) were used as ligands. The rates of ligand-promoted dissolution of goethite were significantly increased in the presence of low concentrations of anionic surfactants (<80 microM SDS; <6 mg/L RhL). At higher surfactant concentrations, however, the effects of surfactants were negligible. The dissolution rates in the presence of surfactants were not correlated with adsorbed amounts of ligands. Three possible factors contributing to these observations were further investigated and discussed: (i) adsorbed surfactants may influence ligand adsorption by changes in the ligand's surface speciation, (ii) re-adsorption of Fe-DFOB or Fe-DFOD complexes may lead to an underestimation of siderophore-promoted dissolution rates at high surfactant concentrations, and (iii) co-adsorption of protons to goethite with SDS may influence the dissolution rates. However, our results show that none of these three factors can satisfactorily explain the observed effects of anionic surfactants on ligand-promoted dissolution rates of iron and aluminum hydroxides.
我们研究了表面活性剂十二烷基硫酸钠（SDS）和鼠李糖脂（RhL）对pH值为6时配体促进针铁矿（α-FeOOH）和勃姆石（γ-AlOOH）溶解的影响。使用了铁载体去铁胺B（DFOB）、其衍生物去铁胺D（DFOD）、乙二胺四乙酸（EDTA）和8-羟基喹啉-5-磺酸（HQS）作为配体。在低浓度阴离子表面活性剂（<80 microM SDS；<6 mg/L RhL）存在下，针铁矿的配体促进溶解速率显著增加。然而，在较高的表面活性剂浓度下，表面活性剂的影响可以忽略不计。表面活性剂存在下的溶解速率与配体的吸附量无关。对导致这些观察结果的三个可能因素进行了进一步研究和讨论：（i）吸附的表面活性剂可能通过改变配体的表面形态来影响配体吸附，（ii）Fe-DFOB或Fe-DFOD络合物的再吸附可能导致在高表面活性剂浓度下对铁载体促进溶解速率的低估，以及（iii）质子与SDS共同吸附到针铁矿上可能影响溶解速率。然而，我们的结果表明，这三个因素都不能令人满意地解释观察到的阴离子表面活性剂对氢氧化铁和氢氧化铝配体促进溶解速率的影响。
