A Critical Salt Concentration of Illite Clay for Particle Release in Aquifer Media

Particle release is the main reason for permeability decrease in the coastal aquifers with the existence of illite clay. In this paper, an attempt was made to determine the CSC with both batch and column experiments. Stepwise decreasing concentrations of NaCl solution were applied until fine particles were released from the sediments and the CSC was determined. The critical oscillation frequency of batch experiment was determined at 150 rpm. The critical salt concentration was 0.054 mol/l determined by column experiments and 0.06 ± 0.005 mol/l by batch experiments, respectively. CSC from batch experiments were compared to those obtained from column experiments. It was found that both of results were nearly consistent with each other. The flow velocity had little impact on the critical salt concentration in those experiments, while ion valence had a significant impact on the critical salt concentration.