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Sujanani R, Nordness O, Miranda A, Katz LE, Brennecke JF, Freeman BD. Accounting for Ion Pairing Effects on Sulfate Salt Sorption in Cation Exchange Membranes. J Phys Chem B 2023; 127:1842-1855. [PMID: 36795084 DOI: 10.1021/acs.jpcb.2c07900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Ion exchange membranes (IEMs) are frequently used in water treatment and electrochemical applications, with their ion separation properties largely governed by equilibrium ion partitioning between a membrane and contiguous solution. Despite an expansive literature on IEMs, the influence of electrolyte association (i.e., ion pairing) on ion sorption remains relatively unexplored. In this study, salt sorption in two commercial cation exchange membranes equilibrated with 0.01-1.0 M MgSO4 and Na2SO4 is investigated experimentally and theoretically. Association measurements of salt solutions using conductometric experiments and the Stokes-Einstein approximation show significant concentrations of ion pairs in MgSO4 and Na2SO4 relative to those in simple electrolytes (i.e., NaCl), which is consistent with prior studies of sulfate salts. The Manning/Donnan model, developed and validated for halide salts in previous studies, substantially underpredicts sulfate sorption measurements, presumably due to ion pairing effects not accounted for in this established theory. These findings suggest that ion pairing can enhance salt sorption in IEMs due to partitioning of reduced valence species. By reformulating the Donnan and Manning models, a theoretical framework for predicting salt sorption in IEMs that explicitly considers electrolyte association is developed. Remarkably, theoretical predictions of sulfate sorption are improved by over an order of magnitude by accounting for ion speciation. In some cases, good quantitative agreement is observed between theoretical and experimental values for external salt concentrations between 0.1 and 1.0 M using no adjustable parameters.
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Affiliation(s)
- Rahul Sujanani
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton Street, Austin, Texas 78712, United States
| | - Oscar Nordness
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton Street, Austin, Texas 78712, United States
| | - Andres Miranda
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton Street, Austin, Texas 78712, United States
| | - Lynn E Katz
- Department of Civil, Architectural, and Environmental Engineering, The University of Texas at Austin, 301 E. Dean Keeton Street, Austin, Texas 78712, United States
| | - Joan F Brennecke
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton Street, Austin, Texas 78712, United States
| | - Benny D Freeman
- McKetta Department of Chemical Engineering, The University of Texas at Austin, 200 E. Dean Keeton Street, Austin, Texas 78712, United States
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Ion and Water Transport in Ion-Exchange Membranes for Power Generation Systems: Guidelines for Modeling. Int J Mol Sci 2022; 24:ijms24010034. [PMID: 36613476 PMCID: PMC9820504 DOI: 10.3390/ijms24010034] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/12/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022] Open
Abstract
Artificial ion-exchange and other charged membranes, such as biomembranes, are self-organizing nanomaterials built from macromolecules. The interactions of fragments of macromolecules results in phase separation and the formation of ion-conducting channels. The properties conditioned by the structure of charged membranes determine their application in separation processes (water treatment, electrolyte concentration, food industry and others), energy (reverse electrodialysis, fuel cells and others), and chlore-alkali production and others. The purpose of this review is to provide guidelines for modeling the transport of ions and water in charged membranes, as well as to describe the latest advances in this field with a focus on power generation systems. We briefly describe the main structural elements of charged membranes which determine their ion and water transport characteristics. The main governing equations and the most commonly used theories and assumptions are presented and analyzed. The known models are classified and then described based on the information about the equations and the assumptions they are based on. Most attention is paid to the models which have the greatest impact and are most frequently used in the literature. Among them, we focus on recent models developed for proton-exchange membranes used in fuel cells and for membranes applied in reverse electrodialysis.
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Huang Y, Sagiv A, Semiat R, Shemer H. Development of a predictive kinetic model with statistically analyzed parameters for Donnan Dialysis process. J Memb Sci 2022. [DOI: 10.1016/j.memsci.2022.120972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Chen X, Goh K. Quantifying the coupled monovalent and divalent ions sorption in dense ion exchange membranes. J Memb Sci 2022. [DOI: 10.1016/j.memsci.2022.121140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kitto D, Kamcev J. Manning condensation in ion exchange membranes: A review on ion partitioning and diffusion models. JOURNAL OF POLYMER SCIENCE 2022. [DOI: 10.1002/pol.20210810] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- David Kitto
- Department of Chemical Engineering University of Michigan, North Campus Research Complex B28 Ann Arbor Michigan USA
| | - Jovan Kamcev
- Department of Chemical Engineering University of Michigan, North Campus Research Complex B28 Ann Arbor Michigan USA
- Macromolecular Science and Engineering University of Michigan, North Campus Research Complex B28 Ann Arbor Michigan USA
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Ramos-Garcés MV, Li K, Lei Q, Bhattacharya D, Kole S, Zhang Q, Strzalka J, Angelopoulou PP, Sakellariou G, Kumar R, Arges CG. Understanding the ionic activity and conductivity value differences between random copolymer electrolytes and block copolymer electrolytes of the same chemistry. RSC Adv 2021; 11:15078-15084. [PMID: 35424026 PMCID: PMC8697982 DOI: 10.1039/d1ra02519h] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 04/15/2021] [Indexed: 11/21/2022] Open
Abstract
Herein, a systematic study where the macromolecular architectures of poly(styrene-block-2-vinyl pyridine) block copolymer electrolytes (BCE) are varied and their activity coefficients and ionic conductivities are compared and rationalized versus a random copolymer electrolyte (RCE) of the same repeat unit chemistry. By performing quartz crystal microbalance, ion-sorption, and ionic conductivity measurements of the thin film copolymer electrolytes, it is found that the RCE has higher ionic activity coefficients. This observation is ascribed to the fact that the ionic groups in the RCE are more spaced out, reducing the overall chain charge density. However, the ionic conductivity of the BCE is 50% higher and 17% higher after the conductivity is normalized by their ion exchange capacity values on a volumetric basis. This is attributed to the presence of percolated pathways in the BCE. To complement the experimental findings, molecular dynamics (MD) simulations showed that the BCE has larger water cluster sizes, rotational dynamics, and diffusion coefficients, which are contributing factors to the higher ionic conductivity of the BCE variant. The findings herein motivate the design of new polymer electrolyte chemistries that exploit the advantages of both RCEs and BCEs.
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Affiliation(s)
- Mario V Ramos-Garcés
- Cain Department of Chemical Engineering, Louisiana State University Baton Rouge LA 70803 USA
| | - Ke Li
- Department of Chemistry, Louisiana State University Baton Rouge LA 70803 USA
| | - Qi Lei
- Cain Department of Chemical Engineering, Louisiana State University Baton Rouge LA 70803 USA
| | - Deepra Bhattacharya
- Cain Department of Chemical Engineering, Louisiana State University Baton Rouge LA 70803 USA
| | - Subarna Kole
- Cain Department of Chemical Engineering, Louisiana State University Baton Rouge LA 70803 USA
| | - Qingteng Zhang
- X-ray Science Division, Argonne National Laboratory Lemont IL 60439 USA
| | - Joseph Strzalka
- X-ray Science Division, Argonne National Laboratory Lemont IL 60439 USA
| | | | - Georgios Sakellariou
- Department of Chemistry, National and Kapodistrian University of Athens 15771 Athens Greece
| | - Revati Kumar
- Department of Chemistry, Louisiana State University Baton Rouge LA 70803 USA
| | - Christopher G Arges
- Cain Department of Chemical Engineering, Louisiana State University Baton Rouge LA 70803 USA
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