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Article The Impact of Quaternization Degree in Polyepichlorohydrin-Based Anion Exchange Membranes on Salinity Gradient Energy Generation by Reverse Electrodialysis(Elsevier, 2025) Cihanoglu, Aydin; Guler, Enver; Kabay, NalanAnion exchange membranes with tailored fixed-charge densities can improve monovalent ion selectivity and performance in reverse electrodialysis for salinity gradient power generation. In this study, poly(epichlorohydrin) was blended with polyacrylonitrile and quaternized with 1,4-diazabicyclo[2.2.2]octane at three different molar ratios to produce AEMs with systematically varied quaternization degrees via a one-step amination/ crosslinking procedure. The resulting membranes were characterized for their physicochemical, electrochemical, and RED performance using ATR-FTIR, XPS, SEM, AFM, water uptake, swelling degree, contact angle, surface zeta potential, ion exchange capacity, fixed charge density, and electrical resistance. Higher quaternization increased the IEC, reduced resistance, and shifted surface charge, leading to improved stack power output in model NaCl solutions. In the presence of Na2SO4, power loss was reduced for more highly quaternized membranes, indicating enhanced exclusion of divalent anions (SO42-) and reduced uphill transport. Fouling tests with humic acid/fulvic acid mixtures showed greater stability for quaternized membranes compared to a commercial benchmark. Moreover, stability tests conducted on fouled membranes revealed that the tailor-made membrane exhibits superior durability and lower fouling-induced power loss than commercial Fujifilm Type II AEMs. Overall, these results demonstrate that tuning the degree of quaternization is an effective strategy to balance conductivity and ion selectivity in AEMs for RED applications.Article Citation - WoS: 18Citation - Scopus: 20Investigations on the Effects of Operational Parameters in Reverse Electrodialysis System for Salinity Gradient Power Generation Using Central Composite Design (ccd)(Elsevier, 2022) Altiok, Esra; Kaya, Tugce Zeynep; Othman, Nur Hidayati; Kinali, Orhan; Kitada, Soma; Guler, Enver; Kabay, NalanReverse electrodialysis (RED) can be utilized for the production of renewable energy from salinity gradients. However, there are many key parameters that could influence the performance of RED. This study investigates the use RSM for development of a predictive power density (PD) and open-circuit voltage (OCV) model for the RED system. A three-factor central composite design (CCD) was used to quantify the effects of flow velocity (X-1), salinity ratio (X-2), and number of cell pairs (X-3) towards PD and OCV. A total of 17 experimental data were fitted and ANOVA was used to validate the accuracy of the models. 3D and surface plots were created to foresee the optimal levels of each variable. It was found that flow velocity and salinity ratio have the most dominant influences on the RED performances as compared to number of cell pairs. The predicted PD and OCV values were found to be reasonably fit with the experimental data, validating the predictability of applied models. Therefore, this study suggests that CCD can be considered an effective tool for evaluating and optimizing the RED system using a minimum number of experiments.Article Citation - Scopus: 1Effect of Asymmetric Feed Flow Rate and Temperature on Reverse Electrodialysis: A Response Surface Methodology Approach(Elsevier, 2025) Gul, Taha Furkan; Gonlugur, Miray Emreol; Guler, Enver; Cihanoglu, Aydin; Kabay, NalanReverse electrodialysis (RED) has the potential to generate sustainable energy by utilizing the salinity gradient potential between natural water sources with different salinities, such as river water and seawater. It is essential to comprehend the RED process's characteristics and optimize operational parameters to enhance its commercial viability. This study investigated the effects of varying inlet feed flow rates and temperatures on RED performance using Response Surface Methodology. Unlike conventional approaches, where inlet flow rates of seawater and river water solutions are typically kept equal, this research explores their diverse combinations. Key performance metrics of RED, including power density and open circuit voltage, were evaluated. Moreover, the impacts of different feed flow rates and temperatures on ohmic and non-ohmic resistances were thoroughly examined. The findings underscore significant interactions between feed flow rates, temperature, and RED performance outputs, providing insights essential for optimizing RED operations and enhancing its practical application in sustainable energy solutions.
