Deposition Dynamics of Rod-Shaped Colloids during Transport in Porous Media under Favorable Conditions

作者：Li Ke; Ma Huilian^*

来源：Langmuir, 2018, 34(9): 2967-2980.

DOI：10.1021/acs.langmuir.7b03983

A three-dimensional computational modeling study of the deposition dynamics of rod shaped colloids during transport in porous media under favorable conditions (no energy barrier to deposition) is presented. The objective was to explore the influences of the particle shape on colloid transport and retention. During simulation, both translation and rotation of ellipsoidal particles were tracked and evaluated based on an analysis of all forces and torques acting on the particle. We observed that the shape was a key factor affecting colloid transport and attachment. Rod particles exhibited enhanced retention compared with spheres of equivalent volume in the size range greater than similar to 200 nm. The shape effect was the most pronounced for particles around 200 nm to 1 mu m under simulated conditions. The shape effect was also strongly dependent upon the fluid velocity; it was most significant at high velocity, but not so at very low velocity. The above-described shape effect on retention was directly related to particle rotation dynamics due to the coupled effects from rotational diffusion and flow hydrodynamics. Rotational diffusion changed the particle orientation randomly, which caused the rod particles to drift considerably across flow streamlines for attachment in the size range from 200 nm to 1 mu m. The hydrodynamic effect induced periodic particle rotation and oscillation, which rendered large-sized rod particles to behave like "spinning bodies," prescribed by their long axes so as to easily intercept with the collector surface for retention. Our findings demonstrated that the practice of using equivalent spheres to approximate rods is inadequate in predicting the transport fate and adhesion dynamics of rod-shaped colloids in porous media.

• 出版日期2018-3-6