Local position of colloid clusters in a packed bed of spheres

Colloid deposition in a model deep bed filter has been imaged using synchrotron-based X-ray tomography. The local position of the colloid clusters with respect to the filter grains has been evaluated using computerized image analysis and a simplified model of the filter grains and the colloid clusters. By matching each cluster to the corresponding nearest neighbor filter grain, the angle of deposition at the filter grain surface was calculated for a representative single sphere collector. By identifying neighboring grains, the distribution of grain–grain contacts was evaluated. Using this distribution, the deposition of colloids in this experiment can be understood in terms of an enhanced deposition close to grain–grain contacts.

► Tomographic imaging of deep bed filtration of colloidal particles. ► Simple image analysis routine for the evaluation of local positions of the colloids. ► Local position of the colloid clusters with respect to a representative grain. ► Grain–grain contact angle determination. ► Experimental evidence for enhanced deposition at grain–grain-contacts.