Browsing by Author "Kabay, Nalan"
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Article Salinity gradient energy conversion by custom-made interpolymer ion exchange membranes utilized in reverse electrodialysis system(Journal of Environmental Chemical Engineering, 2023-04-15) Altıok, Esra; Kaya, Tuğçe Zeynep; Smolinska-Kempisty, Katarzyna; Güler, Enver; Kabay, Nalan; Tomaszewska, Barbara; Bryjak, MarekReverse electrodialysis (RED) is one of methods to extract salinity gradient energy between two aqueous solutions 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+ and 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, and 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.Article Synthesis of Silver Nanoparticle-Immobilized Antibacterial Anion Exchange Membranes for Salinity Gradient Energy Production by Reverse Electrodialysis(ACS Sustainable Chemistry & Engineering, 2024-03-01) Eti, Mine; Cihanoğlu, Aydın; Hamaloğlu, Kadriye Özlem; Altıok, Esra; Güler, Enver; Tuncel, Ali; Kabay, NalanBiofouling, stemming from the attachment of living microorganisms, such as bacteria, which form resilient biofilms on membrane surfaces, presents a significant challenge that hampers the efficiency of anion exchange membranes (AEMs) in reverse electrodialysis (RED) applications. This limitation curtails the generation of electrical power from salinity gradients, which, notably, is a sustainable form of energy known as osmotic energy. Reverse electrodialysis (RED) stands as a clean and promising process to harness this sustainable energy source. This study aimed to impart antibacterial activity to the synthesized AEMs using silver nanoparticles (AgNPs). For that purpose, AgNPs were synthesized at 30oC using two different pH (6.0 and pH 9.0) and immobilized into synthesized AEMs using the dip-coating technique. In nanoparticle synthesis, ascorbic acid (AA) and trisodium citrate (TSC) were used as a reductant and a stabilizer, respectively, to take under control of particle size and agglomeration behavior. The results indicated that AgNPs synthesized at pH 6.0 were dispersed on the AEMs surface without agglomeration. The stability of AgNPs immobilized on the membrane surface was tested under low and high-saline solutions. The antibacterial activities of AEMs were determined with the colony-counting method using Gram-negative (Escherichia coli) bacteria suspension. The viability of bacteria dramatically decreased after the immobilization of AgNPs to the AEMs. In the short and long-term RED tests, it has been observed that the AEMs having AgNPs have high energy-generating potentials, and power density up to 0.372 W/m2 can be obtained.