In this study, the flocculation and the subsequent decantation step of mixed suspensions of 10 nm-sized γ-Fe₂O₃ magnetic nanoparticles and 500 nm-sized beidellite clay platelets was investigated. This work may find application in the field of water treatment, specifically the flocculation processes with magnetically assisted sedimentation. After a short description of the preparation and characterization of the raw materials (nanoparticles and clays), the influence of several parameters (pH, concentrations of nanoparticles and clays etc.) on the amount of flocculated materials was examined, which gave information on the concentration ranges allowing a complete flocculation, together with a better understanding on the interactions between nanoparticles and clays responsible for flocculation. The optimal conditions for magnetically assisted settling were then determined by comparing for each sample sedimentation velocities under gravity and in the presence of a Nd-Fe-B magnet. Finally, the complex multiscale structure of the flocs in water was explored, through the measurement of several bulk properties (zeta-potential and volume measurements, laser granulometry), while the organization of the materials at a microscopic scale was investigated by cryo-transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering (SAXS).

在这项研究中，絮凝和10 nm尺寸的γ -铁混合悬浮液的后续步骤倾析₂ ö ₃研究了磁性纳米粒子和500 nm尺寸的贝得石粘土薄片。这项工作可能会在水处理领域找到应用，特别是在磁辅助沉淀作用下的絮凝过程中。在对原材料（纳米颗粒和粘土）的制备和表征进行简短描述之后，检查了几个参数（pH，纳米颗粒和粘土的浓度等）对絮凝材料量的影响，从而提供了有关浓度的信息允许完全絮凝的范围，以及对引起絮凝的纳米颗粒和粘土之间相互作用的更好理解。然后，通过比较重力和Nd-Fe-B磁体存在下的每个样品沉降速度，确定磁辅助沉降的最佳条件。最后，通过测量几种体积性质（ζ电位和体积测量，激光粒度分析），探索了水中絮凝物的复杂多尺度结构，同时通过低温透射电子研究了微观尺度上的材料组织。显微镜（cryo-TEM）和小角度X射线散射（SAXS）。