$c_i$	ion [i] concentration within pore, mol·m−3
$C_f$	feed-solution concentration, mol·m−3
$C_i$	ion [i] in feed-solution concentration, mol·m−3
$C_p$	uncharged solute bulk permeate concentration, mol·m−3
$D_p$/ $D_{i,p}$	uncharged solute/charged solute pore diffusion coefficient, ${\mathrm{m}}^{2.}\mathrm{s}{-}^1 (=K_d{D}_{\infty })$
$D_{\infty }$	solute bulk diffusion coefficient, m2.s−1
e	electronic charge, $1.602177\times {10}^{-19}\mathrm{C}$
I	ionic strength, mol·m−3
j	number of data points per solute in fitting, dimensionless
$j_i$	ionic flux of ion [i] (pore area basis), mol·m−2·s−1
$j_s$	uncharged solute flux (pore area basis), mol·m−2·s−1
k	feed-side mass transfer coefficient, m/s
k	Boltzmann constant, $1.38066\times {10}^{-23}{\mathrm{JK}}^{-1}$
$K_{i,c}$	hindrance factor for convection of ion I, dimensionless
$K_{i,d}$	ionic hindrance factor for diffusion, dimensionless
P	pressure N/m2
$r_p$	effective pore radius, m
R	rejection (%)
R	universal gas constant, $8.314 \mathrm{J}·{\mathrm{mol}}^{-1}·{\mathrm{K}}^{-1}$
V	solvent velocity, m/s
$X_d$	effective charge density, mol/m3
T	absolute temperature in K
$z_i$	ion [i] valence, dimensionless
x	axial position within the pore, m
${\gamma }_i$	the activity coefficient of ion [i] within the pore, dimensionless
$\Delta P$	applied pressure, N·m−2
${\gamma }_i^0$	the bulk activity coefficient of ion [i], dimensionless
$\Delta P_e$	effective pressure driving force, N·m−2
$\Delta x$	membrane thickness, m
$\Delta \Pi$	the osmotic pressure difference, N·m−2
λ	the ratio of ionic or uncharged solute radius to pore radius, dimensionless
$\Delta {\mathsf{\Psi }}_D$	Donnan potential, V
η	solvent viscosity within pores, N·s·m−2
$\raisebox{1ex}{${\mathsf{\epsilon }}_b$}\!\left/ \!\raisebox{-1ex}{${\mathsf{\epsilon }}_p$}\right.$	bulk/pore dielectric constant, dimensionless
$\xi$	the ratio of effective membrane charge density to bulk feed concentration, dimensionless $(\xi =X_d/C_f)$
${\lambda }_i$	the ratio of ionic radius to pore radius, dimensionless
${\Phi }_i$	the steric partition coefficient of ion [i], dimensionless
$\mathsf{\Psi }$	the potential within the pore, V