Clay-bacteria interaction: Effect of bacterial cell density on sedimentation behavior and fabric map of kaolinite clay
Clay-bacteria interaction: Effect of bacterial cell density on sedimentation behavior and fabric map of kaolinite clay
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DOI：
10.1016/j.clay.2023.106973
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发表时间：
2023
影响因子：
5.6
通讯作者：
H. Joo;T. Kwon;Sheng Dai
中科院分区：
文献类型：
--
作者：
H. Joo;T. Kwon;Sheng Dai
粘土与细菌的相互作用是普遍存在的，细菌的存在对粘土的机械、化学和电学行为有显著的影响。然而，微观尺度的粘土-细菌相互作用对粘土的宏观工程行为和性质的影响仍然知之甚少。这项研究介绍了细菌对高岭石微观结构的影响，以及细菌对高岭土悬浮液的沉降行为。用高岭土和模式菌白纹希万氏菌MR-1组成的悬浮液进行沉降试验，改变溶液的pH值和细胞密度。结果表明，在细菌存在的情况下，高岭石呈现面对面的聚集微结构，这归因于高岭石与细菌细胞之间的阳离子共享和/或交换。同时，当pH值低于高岭石表面等电点时，粘土与细菌的缔合作用较低，这是由于负电荷(高岭石表面和细菌表面)对正电荷(高岭石边缘)的竞争所致。高岭石-细菌缔合引起的组构变化加速了高岭土的沉降，降低了最终的孔隙率。根据高岭石的沉积行为和扫描电子显微镜观察，提出了细菌缔合高岭石的组构图。这项研究促进了对粘土-细菌相互作用和粘土在微生物活性较强的悬浮液中的沉积行为的理解。
Clay-bacteria interactions are ubiquitous and the presence of bacteria has a pronounced effect on the mechanical, chemical, and electrical behaviors of clays. However, the role of microscale clay-bacteria interactions to the macro-scale engineering behaviors and properties of clays remains poorly understood. This study presents changes in the microstructure of kaolinite in association with bacteria and the resulting sedimentation behavior of bacterium-associated kaolin suspensions. Sedimentation tests were performed using suspensions composed of kaolin and model bacteriaShewanella oneidensisMR-1 while varying the fluid pH and cell density. The results reveal that kaolinite presents face-to-face aggregated microstructures with the presence of bacteria, attributable to sharing and/or exchange of cations between kaolinite and bacterial cells. Meanwhile, at a pH value lower than the isoelectric point of the kaolinite edge surfaces, the clay-bacteria association appears less pronounced comparing to the higher pH, owing to the competition between negative (kaolinite faces and bacteria surfaces) over positive (kaolinite edges) charges. The fabric change caused by kaolinite-bacteria association accelerates kaolin settling and reduces the final void ratios. A fabric map for bacterium-asssociated kaolinite is suggested based on the sedimentation behaviors and scanning electron microscopy observations. This study advances the understanding of particle-level clay-bacteria interactions and the sedimentation behavior of clays in suspensions with vigorous microbial activities.