In our DPD model (which follows the approach of Anderson et al. , representing water, sodium, and hydroxyl ions respectively. These latter beads are all the same in the model apart from the charge, in other words free ions in this approach are represented by charged water beads. In developing this model we follow the approach outlined in prior works, where the bead volumes are based on partial molar volumes Durchschlag and Zipper 82 and the interactions between DPD beads upon log P and density measurements. As this method is now well established we do not give more extensive details here, rather we point to the Supporting Information. Following this model, SLSar in the deprotonated state takes the structure