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Bilayered Self-Oriented Membrane Fouling and Impact of Magnesium on CaCO3 Formation during Consecutive Electrodialysis Treatments

“…These changes in the migration rates of the different cations would be due to their different hydrated volumes. In ED, the transport number of cations decreases classically in the series K + > Na + > Ca 2+ > Mg 2+ , but the migration of ions occurs together with their hydration shells . The passing of a solution/membrane interface requires the overcoming of an energy barrier caused by the necessity of a partial dehydration of ions.…”

“…In ED, the transport number of cations decreases classically in the series 29 but the migration of ions occurs together with their hydration shells. 31 The passing of a solution/membrane interface requires the overcoming of an energy barrier caused by the necessity of a partial dehydration of ions. The mineral modified membrane surface is likely to decrease this barrier favorizing the hydrated ions as observed on the opposite way by Kotov et al 31 for hydrophobization of modified anion-exchange membrane surface.…”

“…31 The passing of a solution/membrane interface requires the overcoming of an energy barrier caused by the necessity of a partial dehydration of ions. The mineral modified membrane surface is likely to decrease this barrier favorizing the hydrated ions as observed on the opposite way by Kotov et al 31 for hydrophobization of modified anion-exchange membrane surface. It is proposed that due to the mineral layer, the ion migrating would be partially dehydrated, and since the Mg 2þ has the lowest ionic radius in comparison with the other cations (0.65 A ˚vs 0.95, 1.38, and 0.99 A ˚respectively for Na þ , K þ , and Ca 2þ 32 ), it would be favored.…”

Production of ionic liquids by electrodialysis

“…The water transport number is influenced by the membrane, the size, valence and concentration of the ions in solution [49]. An NMR study indicated that one molecule of choline chloride forms a loose hydration shell with up to 10 water molecules [50] and the hydration number of acetate is 11 [51].…”

High-Performance Thin-Film-Nanocomposite Cation Exchange Membranes Containing Hydrophobic Zeolitic Imidazolate Framework for Monovalent Selectivity

“…The small aperture of ZIF-8 can serve as an effective filter to separate hydrated cations of Mg 2+ (4.28 Å) through a size sieving effect [20,21]. Although there is a significant variation on the reported values of hydrated Na + (between 2.99 and 3.58 Å), in general, the hydrated cations with larger crystal radii have weaker hydration shells, so that the detachment of the hydration shell would occur when ions pass the solution-membrane interface [22,23]. Consequently, ZIF-8 has the right size to separate dehydrated Na + (0.95 Å) and hydrated Mg 2+ [24,25].…”