Unusual mutual influence of electrolytes during pressure-driven transport of their mixtures across charged porous membranes

Ionic interactions in nanofiltration of β casein peptides

“…Hence, with 50 mM added NaCl, the ratio of the very mobile inorganic counterion Na + to the less mobile peptidic counterion climbed from 2 to 18%. Indeed, the rise in the concentration of the more mobile Na + counterions would reduce the counterflow of less mobile counterions (basic peptides) and lead to the rise in their global transfer (Bardot et al, 1995). Therefore, the transmission of basic peptides slightly increased.…”

“…5) because of the charge shielding . However, the interpretation of the rise in the transfer of basic counterion peptides rests with phenomena of competition between counterions (Bardot et al, 1995;Yaroshchuk and Vovkogon, 1994). Indeed, every counterion in the solution would be involved in transmembrane electroosmotic flow from permeate to retentate in order to restore electroneutrality.…”

Influence of coion and counterion size on multi-ionic solution nanofiltration

“…The rejection of counterions by charged membranes has been described in the literature [35,36]. Filtration of ternary mixtures of monovalent ions revealed that the less mobile counterion had a rejection that was less than that of the more mobile counterion.…”

“…The addition of the less mobile counterion improved the retention of the more mobile one, and the decrease in the less mobile counterion was brought about by the addition of the more mobile one. From theoretical studies based on irreversible thermodynamics, the authors explained the experimental results as a consequence of the decompensation of the convective and electric flows of a given counterion after the addition of counterions with different mobilities [36,37].…”

Application of the Charge Regulation Model to Transport of Ions through Hydrophilic Membranes: One-Dimensional Transport Model for Narrow Pores (Nanofiltration)

“…5 is positively charged. Hence, where in our calculations the positive ions are the co-ions, in (37,41) they are the counterions, which reverses the retention-mobility behavior of the cations: in positive membranes a reduced mobility of cations increases the retention while in a negative membrane a reduced mobility of cations decreases the retention, see also (37). Simulations at a pH of 11, where our system becomes negatively charged, indeed showed a decreasing retention with decreasing cation mobility (simulations not reported), confirming that our model results are in qualitative agreement with the experimental results in (40,41).…”