Jørgensen Mads Koustrup, Mattsson Tuve
Center for Membrane Technology, Department of Chemistry and Bioscience, Aalborg University, Fredrik Bajers Vej 7H, DK-9220 Aalborg Øst, Denmark.
Department of Chemistry & Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
Membranes (Basel). 2021 Jan 1;11(1):28. doi: 10.3390/membranes11010028.
Fouling of membranes is still an important limiting factor in the application of membrane technology. Therefore, there is still a need for an in-depth understanding of which parameters affect the (ir)removability of fouling layers, as well as the mechanisms behind fouling. In this study, fluid dynamic gauging (FDG) was used to investigate the influence of charge effects between negatively charged foulant particles and cations on cake cohesive strength. Fouling cakes' thicknesses and cohesive strengths were estimated during membrane operations, where microfiltration (MF) membranes were fouled in a feed-and-bleed cross-flow filtration system with low and highly negatively charged polystyrene-polyacrylic acid core-shell particles. In addition, an added procedure to determine the irremovability of cakes using FDG was also proposed. Comparing layers formed in the presence and absence of calcium ions revealed that layers formed without calcium ions had significantly lower cohesive strength than layers formed in the presence of calcium ions, which is explained by the bridging effect between negatively charged particles and calcium ions. Results also confirmed more cohesive cakes formed by high negative charge particles in the presence of calcium compared to lower negative charge particles. Hence, it was demonstrated that FDG can be used to assess the cohesive strength ((ir)removability) of cake layers, and to study how cake cohesive strength depends on foulant surface charge and ionic composition of the solution.
膜污染仍然是膜技术应用中的一个重要限制因素。因此，仍有必要深入了解哪些参数会影响污染层的（不可）去除性以及污染背后的机制。在本研究中，使用流体动力学测量（FDG）来研究带负电荷的污垢颗粒与阳离子之间的电荷效应对滤饼粘结强度的影响。在膜操作过程中估计了污染滤饼的厚度和粘结强度，其中微滤（MF）膜在具有低电荷和高负电荷的聚苯乙烯 - 聚丙烯酸核壳颗粒的进料 - 排放错流过滤系统中被污染。此外，还提出了一种使用FDG确定滤饼不可去除性的附加程序。比较在有钙离子和无钙离子情况下形成的层，发现没有钙离子时形成的层的粘结强度明显低于有钙离子时形成的层，这可以通过带负电荷的颗粒与钙离子之间的桥连作用来解释。结果还证实，与低负电荷颗粒相比，在有钙离子的情况下，高负电荷颗粒形成的滤饼粘结性更强。因此，证明了FDG可用于评估滤饼层的粘结强度（不可去除性），并研究滤饼粘结强度如何取决于污垢表面电荷和溶液的离子组成。
