Molecular dynamics simulations of both bulk salt solutions and 2D nanoslit systems were performed using the GROMACS simulation package . The transferable force field developed by Loche et al. was used for the sodium (Na + ) and chloride (Cl -) ions, the TIP4P/ force field was used for water, and the parameters for the sulfate (SO -2 4 ) ion were recalibrated for this study as explained in the Supplemental Material. Cross parameters were calculated using the Lorentz-Berthelot mixing rule. Parameters used for this study are summarized in Supplementary Table . The temperature T was imposed using the CSVR thermostat with a default time constant of t CSVR = 0.5 ps, and the pressure P was imposed using a Berendsen barostat with a time constant of 1 ps. Long range electrostatic interactions were handled using the smooth particle mesh Ewald method (SPME) . The LINCS algorithm with the highest order of expansion N LINCS = 4 and one iteration step was used to constrain the geometry of water molecules . Careful analysis of the influence of the Lennard-Jones cutoff discussed in the Supplemental Material reveals convergence for the value employed for production, r LJ = 1.4 nm. The realspace contributions to the electrostatic interaction were cutoff at r C = r LJ and an integration timestep of 1 fs was employed for all simulations. In all simulations, periodic boundary conditions in all directions were employed.