Abbasi Moud Aref
Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
Gels. 2022 Dec 9;8(12):807. doi: 10.3390/gels8120807.
Colloidal behavior of kaolinite particles in water was investigated in this manuscript, without and with the addition of a polymer flocculant (non-anionic polyacrylamide (PAM)), using diverse imaging techniques in addition to LUMisizer. The addition of PAM was found to be causing the formation of bridges among particles thus increasing their settling rates to the bottom of the container. To assess the size of flocs and the potential morphology of PAM around particles and their clusters, the state of flocs formation and polymer distribution was analyzed through various microscopical techniques, namely scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM results revealed that, in the absence of PAM, the floc structure of the sediment was loose and irregularly distributed, while the presence of PAM made the sediment structures greatly denser. Later, using LUMisizer, dynamic light scattering (DLS) and the zeta potential of kaolinite, sedimentation, and colloidal behavior of suspension came under scrutiny. Using LUMisizer, the maximum packing and settling rates of the particles were experimentally obtained as roughly 44 vol%; settling rates were estimated in 63-352 µm/s when centrifugal force varied and, using maximum packing values, compressive yield was estimated to vary between 48-94 kPa. The results of this study are instructive in choosing appropriate polymers and operating conditions to settle clay minerals in tailing ponds. Additionally, the maximum packing of kaolinite particles was simulated with spherical particles with varied polydispersity to connect DLS data to the maximum packing values obtained using LUMisizer; the little discrepancy between simulation and experimental values was found to be encouraging.
本手稿研究了高岭土颗粒在水中的胶体行为，分别考察了不添加和添加聚合物絮凝剂（非离子型聚丙烯酰胺（PAM））的情况，除LUMisizer外还使用了多种成像技术。研究发现，添加PAM会导致颗粒之间形成桥连，从而提高它们向容器底部的沉降速率。为了评估絮凝物的大小以及PAM在颗粒及其聚集体周围的潜在形态，通过各种显微镜技术，即扫描电子显微镜（SEM）和透射电子显微镜（TEM），分析了絮凝物的形成状态和聚合物分布。SEM和TEM结果表明，在没有PAM的情况下，沉积物的絮凝结构松散且分布不规则，而PAM的存在使沉积物结构更加致密。随后，使用LUMisizer、动态光散射（DLS）以及高岭土的zeta电位，对悬浮液的沉降和胶体行为进行了研究。使用LUMisizer，通过实验得到颗粒的最大堆积率和沉降速率约为44%（体积分数）；当离心力变化时，沉降速率估计在63 - 352 µm/s之间，利用最大堆积值，估计压缩屈服强度在48 - 94 kPa之间变化。本研究结果对于选择合适的聚合物和操作条件以沉降尾矿库中的粘土矿物具有指导意义。此外，用具有不同多分散性的球形颗粒模拟了高岭土颗粒的最大堆积情况，以便将DLS数据与使用LUMisizer获得的最大堆积值联系起来；模拟值与实验值之间的微小差异令人鼓舞。
