Surface Charge Effects on Reactive Transports in Microporous Media
The pore-scale understanding of reactive transport with surface charge on solid-liquid interfaces is important for predictions and designs in environmental and energy systems. The existence of surface charge results in various complicated electrokinetic phenomena. However, no efforts have been found that couple electrokinetic and reactive transports together, even though they have been studied much separately. We propose a coupled lattice Boltzmann model which takes the electrokinetics, advection, diffusion and chemical reaction into consideration. The electrical double layer (EDL) effect is implemented into the lattice Boltzmann method (LBM) by modifying the equilibrium distribution for ion concentration. For validation, three cases with analytical solutions are introduced for submodels and they all show good agreements. In a 1-D precipitation case, the modeling results show that when the second Damkohler number is larger than 1, the electrical double layer effect is negligible. Specifically, the electrostatic force leads to a slower transport and depresses the precipitation, so that the active control of surface potential is available for anti-fouling. In a 2-D dissolution case, surface charge on the blocks accelerate the dissolution process. This may be a reason for the discrepancy of previous numerical results and experiments.