Fig. 2. Relative As concentration in the eluent during flow-through desorption from kaolinite before and after a 12-h flow-interruption period. The flow interruption (arrow) was applied to flow-through desorption experiments without or with pre-equilibration of pH of the substrate. The pH of the desorption solution was 5.5 (in the flow-through desorption experiment and in the 7-d pre-equilibrating period).