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Zhou S, Mei Y, Yang W, Jiang C, Guo H, Feng SP, Tang CY. Energy harvesting from acid mine drainage using a highly proton/ion-selective thin polyamide film. WATER RESEARCH 2024; 255:121530. [PMID: 38564897 DOI: 10.1016/j.watres.2024.121530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 03/23/2024] [Accepted: 03/26/2024] [Indexed: 04/04/2024]
Abstract
A huge chemical potential difference exists between the acid mine drainage (AMD) and the alkaline neutralization solution, which is wasted in the traditional AMD neutralization process. This study reports, for the first time, the harvest of this chemical potential energy through a controlled neutralization of AMD using H+-conductive films. Polyamide films with controllable thickness achieved much higher H+ conductance than a commercially available cation exchange membrane (CEM). Meanwhile, the optimal polyamide film had an excellent H+/Ca2+ selectivity of 63.7, over two orders of magnitude higher than that of the CEM (0.3). The combined advantages of fast proton transport and high proton/ion selectivity greatly enhanced the power generation of the AMD battery. The power density was 3.1 W m-2, which is over one order of magnitude higher than that of the commercial CEM (0.2 W m-2). Our study provides a new sustainable solution to address the environmental issues of AMD while simultaneously enabling clean energy production.
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Affiliation(s)
- Shenghua Zhou
- Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR 999077, PR China
| | - Ying Mei
- Research and Development Center for Watershed Environmental Eco-Engineering, Advanced Institute of Natural Sciences, Beijing Normal University, Zhuhai 519087, PR China.
| | - Wulin Yang
- College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China
| | - Chenxiao Jiang
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230052, PR China
| | - Hao Guo
- Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR 999077, PR China; Institute of Environment and Ecology, Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, PR China
| | - Shien-Ping Feng
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR 999077, PR China; Department of Advanced Design and Systems Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR 999077, PR China
| | - Chuyang Y Tang
- Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong SAR 999077, PR China.
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Stolov M, Keisar O, Cohen Y, Freger V. Elucidating the Effect of Aliphatic Molecular Plugs on Ion-Rejecting Properties of Polyamide Membranes. ACS APPLIED MATERIALS & INTERFACES 2022; 14:13335-13343. [PMID: 35263078 DOI: 10.1021/acsami.1c24977] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Polyamide RO membranes are widely used for seawater desalination owing to their high salt rejection and water permeability; however, improved selectivity-permeability trade-off is still desired. "Molecular plugs," small molecules immobilized within the polyamide structure, offer an attractive approach; however, their overall effect on polyamide physicochemical properties poses many questions. Here, we analyze the effect of decylamine, a promising plug, and a few charged and uncharged mimics on polyamide films using several in situ techniques. Electrochemical impedance spectroscopy (EIS) reveals a complex pH-dependent response, whereby, upon exposure to amine solution, conductivity first rapidly drops; however, under alkaline conditions, when amine is uncharged, the trend subsequently slowly reverses, and conductivity increases. This slow reversal was observed for noncharged alcohols of similar size as well, but not for larger surfactant molecules. The reversal was assigned to the uptake of plug molecules within polyamide, as opposed to the fast initial drop assigned to surface adsorption. EIS and quartz-crystal microbalance (QCM) results showed that exposure to decylamine under alkaline conditions ultimately led to an irreversible decrease in conductivity, that is, stronger ion rejection, remaining after re-exposure of polyamide to amine-free buffer. This suggests that plug uptake within polyamide resulted in polymer stress, indeed observed in surface stress measurements, and subsequent relaxation. The results indicate that the moderate size of decylamine and conditions minimizing its charge were optimal for irreversible change; however, charge interactions helped maximize its binding within polymer and induce the desired sustained change in selectivity. The results have many potential implications for improving current membrane desalination technology and increasing inherent membrane selectivity toward hard-to-remove species.
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Affiliation(s)
- Mikhail Stolov
- Wolfson Department of Chemical Engineering, Technion - IIT, Haifa 32000, Israel
| | - Or Keisar
- Nancy and Stephen Grand Technion Energy Program, Technion - IIT, Haifa 32000, Israel
- Nuclear Research Centre-Negev, P.O.B. 9001, Be'er Sheva 84190, Israel
| | - Yair Cohen
- Nuclear Research Centre-Negev, P.O.B. 9001, Be'er Sheva 84190, Israel
| | - Viatcheslav Freger
- Wolfson Department of Chemical Engineering, Technion - IIT, Haifa 32000, Israel
- Nancy and Stephen Grand Technion Energy Program, Technion - IIT, Haifa 32000, Israel
- Grand Water Research Institute, Technion - IIT, Haifa 32000, Israel
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Abstract
Escalating global water scarcity necessitates high-performance desalination membranes, for which fundamental understanding of structure-property-performance relationships is required. In this study, we comprehensively assess the ionization behavior of nanoporous polyamide selective layers in state-of-the-art nanofiltration (NF) membranes. In these films, residual carboxylic acids and amines influence permeability and selectivity by imparting hydrophilicity and ionizable moieties that can exclude coions. We utilize layered interfacial polymerization to prepare physically and chemically similar selective layers of controlled thickness. We then demonstrate location-dependent ionization of carboxyl groups in NF polyamide films. Specifically, only surface carboxyl groups ionize under neutral pH, whereas interior carboxyl ionization requires pH >9. Conversely, amine ionization behaves invariably across the film. First-principles simulations reveal that the low permittivity of nanoconfined water drives the anomalous carboxyl ionization behavior. Furthermore, we report that interior carboxyl ionization could improve the water-salt permselectivity of NF membranes over fourfold, suggesting that interior charge density could be an important tool to enhance the selectivity of polyamide membranes. Our findings highlight the influence of nanoconfinement on membrane transport properties and provide enhanced fundamental understanding of ionization that could enable novel membrane design.
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Freger V. Ion partitioning and permeation in charged low-T* membranes. Adv Colloid Interface Sci 2020; 277:102107. [PMID: 32000110 DOI: 10.1016/j.cis.2020.102107] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 01/15/2020] [Accepted: 01/16/2020] [Indexed: 11/25/2022]
Abstract
Understanding ion transport in membrane materials is key to engineering and development of desalination and water purification technologies as well as electro-membrane applications. To date, modeling of ion transport has mainly relied on mean-field approaches, originally intended for weak inter-ionic interactions, i.e., high reduced temperature T*. This condition is violated in many membranes, which could explain disagreement between predicted trends and experiments. The paper highlights observed discrepancies and develops a new approach based on the concept of ion association, more adequate in the low-T⁎ limit. The new model addresses ion binding and mobility consistently within the same physical picture, applied to different types of single and mixed salts. The resulting relations show a significantly weaker connection between ion partitioning and permeability than the standard ones. Estimates using primitive model (PM) of ions in a homogeneous dielectric suggest that non-PM mechanisms, originating from the molecular structure of the ion-solvating environment, might enhance ion association in membranes. PM analysis also predicts that ion solvation and association must be rigidly related, yet non-PM effects may decouple these phenomena and allow a crossover to non-trivial regimes consistent with experiments and simulations. Despite the crude nature of the presented approach and some questions remaining open, it appears to explain most available experimental data and presents a step towards predictive modeling of ion-selective membrane separations in water-, environment- and energy-related applications.
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Liu J, Chen Z, Yao L, Wang S, Huang L, Dong C, Niu L. The 2D platelet confinement effect on the membrane hole structure probed by electrochemical impedance spectroscopy. Electrochem commun 2019. [DOI: 10.1016/j.elecom.2019.106517] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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Nativ P, Fridman-Bishop N, Gendel Y. Ion transport and selectivity in thin film composite membranes in pressure-driven and electrochemical processes. J Memb Sci 2019. [DOI: 10.1016/j.memsci.2019.04.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Yaroshchuk A, Bruening ML, Zholkovskiy E. Modelling nanofiltration of electrolyte solutions. Adv Colloid Interface Sci 2019; 268:39-63. [PMID: 30951927 DOI: 10.1016/j.cis.2019.03.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 03/08/2019] [Accepted: 03/08/2019] [Indexed: 11/18/2022]
Abstract
This review critically examines current models for nanofiltration (NF) of electrolyte solutions. We start from linear irreversible thermodynamics, we derive a basic equation set for ion transfer in terms of gradients of ion electrochemical potentials and transmembrane volume flux. These equations are extended to the case of significant differences of thermodynamic forces across the membrane (continuous version of irreversible thermodynamics) and solved in quadratures for single salts and trace ions added to single salts in the case of macroscopically-homogeneous membranes. These solutions reduce to (quasi)analytical expressions in the popular Spiegler-Kedem approximation (composition-independent phenomenological coefficients), which we extend to the case of trace ions. This enables us to identify membrane properties (e.g. ion permeances, ion reflection coefficients, electrokinetic charge density) that control its performance in NF of multi-ion solutions. Further, we specify the phenomenological coefficients of irreversible thermodynamics in terms of ion partitioning, hindrance and diffusion coefficients for the model of straight cylindrical capillaries. The corresponding expressions enable assessment of the applicability of the popular nanopore model of NF. This model (based on the use of macroscopic approaches at nanoscale) leads to a number of trends that have never been observed experimentally. We also show that the use of the Born formula (frequently employed for the description of dielectric exclusion) hardly leads to meaningful values of solvent dielectric constant in membrane pores because this formula disregards the very solvent structure whose changes are supposed to bring about the reduction of dielectric permittivity in nanopores. We conclude that the effect should better be quantified in terms of ion excess solvation energies in the membrane phase. As an alternative to the nanopore description of NF, we review recent work on the development of an advanced engineering model for NF of multi-ion solutions in terms of a solution-diffusion-electromigration mechanism. This model (taking into account spontaneously arising transmembrane electric fields) captures several trends observed experimentally, and the use of trace ions can provide model parameters (ion permeances in the membrane) from experiment. We also consider a recent model (ultrathin barrier layers with deviations from local electroneutrality) that may reproduce observed feed-salt concentration dependences of membrane performance in terms of concentration-independent properties like excess ion solvation energies. Due to its complexity, practical modelling of nanofiltration will probably be performed with advanced engineering models for the foreseeable future. Although mechanistic studies are vital for understanding transport and developing membranes, future simulations in this area will likely need to depart from typical continuum models to provide physical insight. For enhancing the quality of modelling input, it is essential to improve the control of concentration polarization in membrane test cells.
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Affiliation(s)
- Andriy Yaroshchuk
- ICREA, Barcelona, Spain; Department of Chemical Engineering, Polytechnic University of Catalonia, Barcelona Tech, Spain.
| | - Merlin L Bruening
- Department of Chemical & Biomolecular Engineering, University of Notre Dame, Notre Dame, IN, USA
| | - Emiliy Zholkovskiy
- F.D.Ovcharenko Institute of Bio-Colloid Chemistry, National Academy of Science of Ukraine, Kyiv, Ukraine
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Stolov M, Freger V. Degradation of Polyamide Membranes Exposed to Chlorine: An Impedance Spectroscopy Study. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:2618-2625. [PMID: 30707583 DOI: 10.1021/acs.est.8b04790] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Polyamide is the key material in modern membrane desalination; however, its well-known and incompletely understood drawback is its low tolerance to chlorine, the most efficient in-line disinfectant. Here we report a first investigation of the mechanism and kinetics of chlorine attack using electrochemical impedance spectroscopy (EIS) that directly probes changes in ion permeation upon chlorination at different pH values, focusing on its early stages and low chlorine concentrations (15-197 ppm). EIS results partly conform to an established two-stage mechanism that proceeds as N-chlorination followed by either C-chlorination in acidic conditions or amide bond scission in alkaline conditions. However, early time kinetics in acidic conditions shows inconsistencies with this model, explained by possible effects of direct ring chlorination and finite polymer relaxation rates. The findings indicate that (a) N-chlorination reduces membrane polarity and ion permeability, while C-chlorination has an opposite effect; (b) chlorination in acidic conditions must involve other reactions, such as direct ring chlorination, in addition to N-chlorination and Orton rearrangement; and (c) the ultimate chemical transformations (C-chlorination or amide bond scission) result in an irreversible increase in membrane polarity and loss of ion rejection. The results highlight the potential of EIS as a powerful and sensitive tool for studying chemical degradation of ion-selective materials that may assist in developing new chlorine-resistant membranes.
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Fridman-Bishop N, Freger V. What makes aromatic polyamide membranes superior: New insights into ion transport and membrane structure. J Memb Sci 2017. [DOI: 10.1016/j.memsci.2017.06.035] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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