Effect of rhamnolipid biosurfactant on transport and retention of iron oxide nanoparticles in water-saturated quartz sand
Effect of rhamnolipid biosurfactant on transport and retention of iron oxide nanoparticles in water-saturated quartz sand
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DOI：
10.1039/d0en01033b
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发表时间：
2021-01
期刊：
影响因子：
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通讯作者：
Shuchi Liao;A. Ghosh;M. Becker;L. Abriola;Natalie L. Cápiro;J. Fortner;K. Pennell
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文献类型：
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作者：
Shuchi Liao;A. Ghosh;M. Becker;L. Abriola;Natalie L. Cápiro;J. Fortner;K. Pennell
虽然以前的研究已经研究了溶液成分，包括溶解的有机物和合成的聚合物，对纳米颗粒在多孔介质中移动的影响，但对微生物分泌的生物表面活性剂对纳米材料的传输和保留行为的影响的关注要少得多。本研究的目的是探讨鼠李糖脂(一种与生物膜相关的生物表面活性剂)对氧化铁纳米颗粒(IONPs)在水饱和石英砂中迁移和滞留的影响。柱实验采用好氧介质(离子强度=50.4 mm)或10 mMNaC l作为背景电解质，孔速为0.43m/d，pH为6.8±0.2。在好氧介质柱中，单独注射IONP时，几乎所有引入的纳米颗粒都被保留了下来，而10 mg L−1和50 mg L−1鼠李糖脂的存在分别使注入的IONP质量的∼和∼分别有25%和50%的突破。此外，含50 mg L−1鼠李糖脂的预冲洗介质可使IONP的质量穿透率进一步提高∼30%。在低离子强度(10mMNaC L)柱中，50 mg L−1鼠李糖脂对纳米颗粒迁移率的促进作用也是相似的。将纳米颗粒过滤器成熟和生物表面活性剂竞争吸附结合在一起的数学模型成功地再现了实验观察。模拟结果表明，在鼠李糖脂的存在下，IONP滤膜的成熟速率系数将下降数量级，IONP的平均截留能力将下降三倍，这与稳定作用和对表面位置的竞争相一致。这些发现表明，鼠李糖脂生物表面活性剂可以潜在地提高纳米材料在地下环境中的稳定性和流动性，在评估生物过程对纳米颗粒在多孔介质中的去向和传输的影响时，应该考虑这些影响。
Although prior studies have investigated the effects of solution constituents, including dissolved organic matter and synthetic polymers, on nanoparticle mobility in porous media, far less attention has been directed toward evaluating the impacts of biosurfactants secreted by microorganisms on the transport and retention behavior of nanomaterials. The objective of this study was to explore the influence of rhamnolipid, a biosurfactant associated with biofilms, on the transport and retention of iron oxide nanoparticles (IONPs) in a water-saturated quartz sand. Column experiments were conducted using aerobic medium (ionic strength = 50.4 mM) or 10 mM NaCl as background electrolyte at a pore velocity of 0.43 m per day and pH 6.8 ± 0.2. In aerobic medium columns, nearly all introduced nanoparticles were retained when IONPs were injected alone, whereas the presence of 10 mg L−1 or 50 mg L−1 rhamnolipid resulted in ∼25% and ∼50% breakthrough of the injected IONP mass, respectively. Moreover, preflushing media with 50 mg L−1 rhamnolipid further increased IONP mass breakthrough by ∼30%. Similar enhancement of nanoparticle mobility by 50 mg L−1 rhamnolipid was also measured in lower ionic strength (10 mM NaCl) columns. Mathematical models that incorporated nanoparticle filter ripening and biosurfactant competitive adsorption successfully reproduced experimental observations. Modeling results predicted an order-of-magnitude decrease in IONP filter ripening rate coefficient and a three-fold drop in average IONP retention capacity in the presence of rhamnolipid, consistent with a stabilizing effect and competition for surface sites. These findings demonstrate that rhamnolipid biosurfactant can potentially enhance nanomaterial stability and mobility in subsurface environments and that these effects should be considered when evaluating the impact of biological process on nanoparticle fate and transport in porous media.