Modeling of Divalent/Monovalent Ion Selectivity of Ion-Exchanger-Based Solvent Polymeric Membranes Doped with Coexchanger

2000 ◽  
Vol 72 (20) ◽  
pp. 4965-4972 ◽  
Author(s):  
Konstantin N. Mikhelson ◽  
Andrzej Lewenstam
Keyword(s):  
Ion Selectivity ◽  
Polymeric Membranes ◽  
Ion Exchanger ◽  
Monovalent Ion

scholarly journals Long-lasting, monovalent-selective capacitive deionization electrodes

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Eric N. Guyes ◽  
Amit N. Shocron ◽  
Yinke Chen ◽  
Charles E. Diesendruck ◽  
Matthew E. Suss
Keyword(s):  
Water Treatment ◽  
Ionic Conductivity ◽  
Ion Selectivity ◽  
Single Step ◽  
Carbon Electrodes ◽  
Capacitive Deionization ◽  
Treatment Technologies ◽  
Porous Carbon Electrodes ◽  
Monovalent Ion ◽  
Direct Use

AbstractEmerging water purification applications often require tunable and ion-selective technologies. For example, when treating water for direct use in irrigation, often monovalent Na+ must be removed preferentially over divalent minerals, such as Ca2+, to reduce both ionic conductivity and sodium adsorption ratio (SAR). Conventional membrane-based water treatment technologies are either largely non-selective or not dynamically tunable. Capacitive deionization (CDI) is an emerging membraneless technology that employs inexpensive and widely available activated carbon electrodes as the active element. We here show that a CDI cell leveraging sulfonated cathodes can deliver long-lasting, tunable monovalent ion selectivity. For feedwaters containing Na+ and Ca2+, our cell achieves a Na+/Ca2+ separation factor of up to 1.6. To demonstrate the cell longevity, we show that monovalent selectivity is retained over 1000 charge–discharge cycles, the highest cycle life achieved for a membraneless CDI cell with porous carbon electrodes to our knowledge, while requiring an energy consumption of ~0.38 kWh/m3 of treated water. Furthermore, we show substantial and simultaneous reductions of ionic conductivity and SAR, such as from 1.75 to 0.69 mS/cm and 19.8 to 13.3, respectively, demonstrating the potential of such a system towards single-step water treatment of brackish and wastewaters for direct use in irrigation.

scholarly journals Mapping the Importance of 4 factors in Creating Monovalent Ion Selectivity in Biological Molecules

2011 ◽  
Vol 100 (3) ◽  
pp. 578a
Author(s):  
Michael Thomas ◽  
Dylan Jayatilaka ◽  
Ben Corry
Keyword(s):  
Ion Selectivity ◽  
Biological Molecules ◽  
Monovalent Ion

scholarly journals Foldamer-Based Ultrapermeable and Highly Selective Artificial Aquaporins that Exclude Protons

2020 ◽  
Author(s):  
Arundhati Roy ◽  
Jie Shen ◽  
Himanshu Joshi ◽  
Woochul Song ◽  
Yu-Ming Tu ◽  
...  
Keyword(s):  
Water Transport ◽  
Recent Progress ◽  
Ion Selectivity ◽  
High Water ◽  
High Rate ◽  
Water Molecules ◽  
Monovalent Ion ◽  
Hallmark Feature ◽  
Artificial Water ◽  
Made In

The outstanding capacity of aquaporins (AQPs) for mediating highly selective superfast water transport1-7 has inspired recent development of supramolecular monovalent ion-excluding artificial water channels (AWCs). AWC-based bioinspired membranes are proposed for desalination, water purification, and other separations applications8-18. While some recent progress has been made in synthesizing AWCs that approach the water permeability and ion selectivity of AQPs, a hallmark feature of AQPs – high water transport while excluding protons has not been reproduced. We report on a class of biomimetic, helically folded pore-forming polymeric foldamers, that can serve as long sought-after highly selective ultrafast water-conducting channels exceeding those of AQPs (1.1 × 1010 H2O molecules/s for AQP17), with high water over monovalent ion transport selectivity (~108 water molecules over Cl- ion) conferred by the modularly tunable hydrophobicity of the interior pore surface. The best-performing AWC reported here delivers water transport at an exceptionally high rate, 2.5 times that of AQP1, while concurrently rejecting salts (NaCl and KCl) and even protons.

scholarly journals Foldamer-Based Ultrapermeable and Highly Selective Artificial Aquaporins that Exclude Protons

2020 ◽  
Author(s):  
Arundhati Roy ◽  
Jie Shen ◽  
Himanshu Joshi ◽  
Woochul Song ◽  
Yu-Ming Tu ◽  
...  
Keyword(s):  
Water Transport ◽  
Recent Progress ◽  
Ion Selectivity ◽  
High Water ◽  
High Rate ◽  
Water Molecules ◽  
Monovalent Ion ◽  
Hallmark Feature ◽  
Artificial Water ◽  
Made In

The outstanding capacity of aquaporins (AQPs) for mediating highly selective superfast water transport1-7 has inspired recent development of supramolecular monovalent ion-excluding artificial water channels (AWCs). AWC-based bioinspired membranes are proposed for desalination, water purification, and other separations applications8-18. While some recent progress has been made in synthesizing AWCs that approach the water permeability and ion selectivity of AQPs, a hallmark feature of AQPs – high water transport while excluding protons has not been reproduced. We report on a class of biomimetic, helically folded pore-forming polymeric foldamers, that can serve as long sought-after highly selective ultrafast water-conducting channels exceeding those of AQPs (1.1 × 1010 H2O molecules/s for AQP17), with high water over monovalent ion transport selectivity (~108 water molecules over Cl- ion) conferred by the modularly tunable hydrophobicity of the interior pore surface. The best-performing AWC reported here delivers water transport at an exceptionally high rate, 2.5 times that of AQP1, while concurrently rejecting salts (NaCl and KCl) and even protons.

Tip size of ion-exchanger based K+-selective microelectrodes. I. Effects on selectivity

1987 ◽  
Vol 65 (5) ◽  
pp. 889-893 ◽  
Author(s):  
Walter G. Carlini ◽  
Bruce R. Ransom
Keyword(s):  
Ion Selectivity ◽  
Ion Exchanger ◽  
Size Dependent

Double-barreled ion-exchanger based K+ -selective microelectrodes (K+ ISMs) of a variety of tip diameters were used to study the dependency of ion selectivity upon tip size. The selectivity of K+ ISMs depended on tip size and barrel configuration. Within the range of tip diameters tested (~ 0.5–6 μm) all K+ ISMs constructed of two barrels glued side by side ("figure-eight glass") exhibited sensitivity to K+ and NH4+. Figure-eight K+ ISMs with tip diameters < 1.5 μm were not sensitive to tetramethylammonium, tetraethylammonium, or choline, whereas K+ ISMs with tip diameters ≥ 1.5 μm sensed all of the quaternary amines. Tip size dependent selectivity was not present in K+ ISMs made from thick septum theta glass. The explanation for tip size dependent changes in ion selectivity is unknown but a discussion of theoretical possibilities is given.

scholarly journals Monovalent Ion Selectivity of the Homotetrameric Bacterial Na Channel, NaChBac

2012 ◽  
Vol 102 (3) ◽  
pp. 603a-604a
Author(s):  
Rocio K. Finol-Urdaneta ◽  
Ahmed Al-Sabi ◽  
Sergei Noskov ◽  
Robert J. French
Keyword(s):  
Ion Selectivity ◽  
Na Channel ◽  
Monovalent Ion
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