Abstract Rhamnolipids, iron (oxyhydr)oxides and clay minerals are promising agents for mitigating metal and metalloid pollution in the environment. In this study, the adsorption of As(III), As(V), Cr(VI), Cd(II) and Pb(II) on ferrihydrite, goethite, montmorillonite and nontronite, and the impacts of rhamnolipids on their desorption were systematically investigated. As(III), As(V) and Cr(VI) were adsorbed on ferrihydrite and goethite with better adsorptions at lower pH, and their maximum adsorptions ranged from 58.8% to 90.7%. Increased pH enhanced the Cd(II) adsorption on all the tested minerals and the maximum adsorption was 96.6% on montmorillonite at pH 8.0. Pb(II) was completely adsorbed on goethite, montmorillonite and nontronite. Rhamnolipids desorbed Cd(II) and Pb(II) from the minerals, but had no impact on the adsorbed As(III), As(V) and Cr(VI). The maximum desorption of Cd(II) and Pb(II) was 79.6% and 54.0% respectively. Most of the adsorption and desorption kinetics were described well by the pseudo-second order model but the Cd(II) desorption from iron (oxyhydr)oxides was fitted better by the simple Elovich model. These results indicate that the adsorptions of metals and metalloids are both mineral- and pH-dependent. Moreover, rhamnolipids are applicable for enhancing the release of cationic metals associated with minerals in the bioremediation process via washing.

中文翻译：

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生物表面活性剂鼠李糖脂会影响铁（羟基）氧化物和粘土矿物上吸附的 As(III)、As(V)、Cr(VI)、Cd(II) 和 Pb(II) 的解吸

摘要 鼠李糖脂、铁（羟基）氧化物和粘土矿物是减轻环境中金属和准金属污染的有前途的试剂。本研究系统地研究了水铁矿、针铁矿、蒙脱石和绿脱石对 As(III)、As(V)、Cr(VI)、Cd(II) 和 Pb(II) 的吸附以及鼠李糖脂对其解吸的影响调查。As(III), As(V) 和 Cr(VI) 被吸附在水铁矿和针铁矿上，在较低的 pH 值下具有更好的吸附性，它们的最大吸附范围为 58.8% 到 90.7%。pH 值的增加增强了对所有测试矿物的 Cd(II) 吸附，在 pH 8.0 的蒙脱石上的最大吸附率为 96.6%。Pb(II) 完全吸附在针铁矿、蒙脱石和绿脱石上。鼠李糖脂从矿物中解吸 Cd(II) 和 Pb(II)，但对吸附的 As(III) 没有影响，As(V) 和 Cr(VI)。Cd(II) 和 Pb(II) 的最大解吸率分别为 79.6% 和 54.0%。大多数吸附和解吸动力学都可以通过伪二级模型很好地描述，但简单的 Elovich 模型更适合从铁（羟基）氧化物中解吸 Cd(II)。这些结果表明金属和准金属的吸附都依赖于矿物和 pH 值。此外，鼠李糖脂适用于通过洗涤增强生物修复过程中与矿物质相关的阳离子金属的释放。这些结果表明金属和准金属的吸附都依赖于矿物和 pH 值。此外，鼠李糖脂适用于通过洗涤增强生物修复过程中与矿物质相关的阳离子金属的释放。这些结果表明金属和准金属的吸附都依赖于矿物和 pH 值。此外，鼠李糖脂适用于通过洗涤增强生物修复过程中与矿物质相关的阳离子金属的释放。