Visualization of nanoparticles deposits onto spherical collectors

In order to develop predictive models dealing with the granular beds clogging by nanoparticles, the deposit morphology on the collectors is a key information. Therefore, we decided to observe this type of deposit both on a magnetic beads line and a magnetic beads layer mounted on a rotating frame with a set of microscopes. The use of magnetic beads ensures that the collectors are kept rigidly connected in both cases without using any support that would disrupt the flow and thus the deposit structure. In the case of the beads layer, the pressure drop increase during the clogging was also monitored to be correlated with the observed pores closure state.
The results of the beads line experiments permitted to show, thanks to the rotating frame, that the deposit is homogenous all over the collector surface in the case of Brownian particles deposition. The observations conducted on the beads layer and a theoretical modeling indicated that the whole air flow passes through the unblocked area of the pores. These results permitted to better understand the clogging process and were useful for the development of a predictive deep bed filtration model.