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Review Citation - Scopus: 7Ion Exchange Membranes for Reverse Electrodialysis (red) Applications - Recent Developments(Amirkabir University of Technology - Membrane Processes Research Laboratory, 2021) Eti,M.; Othman,N.H.; Guler,E.; Kabay,N.The innovative membrane-based technology called reverse electrodialysis (RED) is capable of producing electrical power from the controlled mixing of two aqueous streams of different salinity. There has been tremendous progress so far in the development of RED process in terms of system development, spacer design, membranes properties and operational conditions optimization. Among those, characteristics of the ion exchange membranes are found to be the critical element affecting the performances of RED process. In this respect, a brief overview of the latest developments in ion exchange membranes were presented in this review, focussing on their properties and performances in RED applications. The recent developments of nanocomposite and ion selective membranes, particularly pore filling ion exchange membranes due to their high performances and inexpensive fabrication cost were also summarized. Shortly, fouling problem for the ion exchange membranes employed in the RED system was mentioned. © 2021 Amirkabir University of Technology - Membrane Processes Research Laboratory. All rights reserved.Article Citation - WoS: 6Citation - Scopus: 6Salinity Gradient Energy Conversion by Custom-Made Interpolymer Ion Exchange Membranes Utilized in Reverse Electrodialysis System(Elsevier Sci Ltd, 2023) Altiok, Esra; Kaya, Tugce Zeynep; Smolinska-Kempisty, Katarzyna; Guler, Enver; Kabay, Nalan; Tomaszewska, Barbara; Bryjak, MarekReverse electrodialysis (RED) is one of methods to extract salinity gradient energy between two aqueous solu-tions with different salt concentrations. In this work, custom-made interpolymer ion exchange membranes were employed in the RED stack. The effects of divalent (Mg2+, Ca2+ , SO42-) and monovalent (Li+, K+ and Cl-) ions in the feed solutions prepared from NaCl salt as a function of such process parameters as number of membrane pairs, flow rate , salinity ratio on power generation by the RED method were studied. It was shown that the maximum power density of 0.561 W/m2 was reached by using three membrane pairs using 1:45 of salt ratio with a feed flow rate of 120 mL/min using only NaCl salt in the feed solutions. The maximum power density was 0.398 W/m2 at 120 mL/min of the flow rate of the feed solutions composed of 90 wt% NaCl and 10 wt% KCl by using a salt ratio of 1:30 while the lowest power density of 0.246 W/m2 was obtained with a feed flow rate of 30 mL/min in the presence of SO42-ions with a similar salt ratio. Consequently, it was seen that while the presence of divalent ions in NaCl solutions had negative impact on power generation by RED system, the addition of monovalent ions having smaller hydrated radius than that of the Na+ ions contributed positively to the power generation.Book Part Citation - Scopus: 2Green Energy Generation Using Membrane Technologies Based on Salinity Gradient(Elsevier, 2023) Güler,E.; Cihanoğlu,A.; Altıok,E.; Kaya,T.Z.; Eti,M.; Kabay,N.Electrical energy can be extracted from salinity gradients, often represented by two aqueous solutions with different salinities. This becomes very interesting when sustainable and practical electromembrane processes can be applied to convert the salinity gradient power into electric power. Reverse electrodialysis (RED), in this context, has gained much interest in the last few years. In addition to many operational and design parameters affecting the process output, ion exchange membranes (IEMs) represent core elements in RED. In this chapter, it is aimed to introduce and discuss the current trend of IEMs as well as vital operational parameters and fouling affecting the RED performance. © 2023 Elsevier Inc. All rights reserved.Book Part Citation - Scopus: 12Water Flux and Reverse Salt Flux(Elsevier, 2018) Koseoglu,H.; Guler,E.; Harman,B.I.; Gonulsuz,E.Following the increase in the world population and the demand for economic development, the need for energy has increased day by day. Rapidly increasing global energy consumption is supplied mainly by fossil fuels bearing the risk of exhaustion with decreasing reserves, which now have the effect of carbon emissions and greenhouse gases. These concerns lead humanity to significantly reduce the use of fossil fuels. Salinity gradient energy (SGP), a type of hydroelectric energy, also has a high potential to displace fossil fuels. SGP is less periodic than sources like wind and solar energy. The osmotic pressure gradient energy uses the released energy during mixing of the water currents with different salinity The Gibbs free energy from mixing two solutions of different concentrations is an unnoticed source of energy. Salinity gradient energy, also referred to as osmotic energy or blue energy, can be derived from natural sources such as clean river water, salt water, and desalination of seawater. Various approaches have been developed to capture salinity gradient energy, but the most promising are pressure-retarded osmosis (PRO), reverse electrodialysis (RED) and forward osmosis (FO) processes. In this chapter theoretical approaches derived from the current literature is presented for the deep conceptual understanding of the water flux and reverse salt flux issues. © 2018 Elsevier B.V. All rights reserved.Review Citation - Scopus: 30Reverse Electrodialysis for Salinity Gradient Power Generation: Challenges and Future Perspectives(Amirkabir University of Technology - Membrane Processes Research Laboratory, 2018) Güler,E.; Nijmeijer,K.Salinity gradient energy, which is also known as Blue energy, is a renewable energy form that can be extracted from the mixing of two solutions with different salinities. About 80% of the current global electricity demand could potentially be covered by this energy source. Among several energy extraction technologies, reverse electrodialysis (RED), using anion and cation exchange membranes for ionic transport that is converted into an electrical current at the electrodes, is most promising. This study provides a brief overview of recent advances in RED technology. Furthermore, it discusses future research directions and prospects to expand the true potential of this technology for power generation. Major emphasis should be on the development of task-specific membranes and stacks, the control of fouling and the design of new applications and hybrid processes. © 2018 MPRL. All rights reserved.
