Researcher: Keskin, Seda
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Keskin, Seda
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Publication Metadata only [BMIM][OAc] coating layer makes activated carbon almost completely selective for CO2(Elsevier Science Sa, 2022) N/A; N/A; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Durak, Özce; Zeeshan, Muhammad; Keskin, Seda; Uzun, Alper; Master Student; PhD Student; Faculty Member; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; 40548; 59917Tuning the molecular affinity of porous materials towards desired gases is important to achieve superior selectivity for a target separation. Herein, we report a novel composite, prepared by coating an ordinary activated carbon (AC) with an ionic liquid (IL) (1-butyl-3-methylimidazolium acetate, [BMIM][OAc]) offering an almost complete CO2 selectivity over N-2 and CH4. Data indicated that pore blockage by the IL accompanied with the enhancement in polarity and reduction in the hydrophobic character of the surface hindered the sorption of N-2 and CH4. For CO2, on the other hand, new chemisorption and physisorption sites became available associated with the IL layer on the surface, making the composite material significantly selective. Newly formed chemisorption sites attributed to the cation's acidic C2H sites, which become available with bi-layer formation. Presence of multiple competitive sorption sites with different energies was further proven with thermal analysis and detailed spectroscopic analysis. Data showed that CO2/CH4 and CO2/N-2 ideal selectivities boosted from 3.3 to 688.3 (2.3 to 54.7) and from 15.6 to 903.7 (7.1 to 74.3) at 0.1 (1) bar and 25 degrees C, respectively, upon the deposition of IL layer. Especially at lower pressures, the IL/AC material became almost fully selective for CO2 offering ideal selectivities in the order of several tens of thousands. To the best of our knowledge, the remarkable enhancement in the ideal CO2 selectivity by a straightforward post-synthesis modification of an ordinary AC, as reported here, sets a new benchmark in high-performance and efficient gas separation for similar porous materials.Publication Metadata only Opportunities and challenges of MOF-based membranes in gas separations(Elsevier, 2015) Avci, Ahmet K.; N/A; Department of Chemical and Biological Engineering; Adatoz, Elda Beruhil; Keskin, Seda; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 40548Gas separation using metal organic framework (MOF) membranes has become an increasingly important research field over the last years. Several recent studies have shown that thin-film MOF membranes and MOF/polymer composite membranes can outperform well known polymer and zeolite membranes in various gas separation applications. The continuously increasing number of experimental and computational studies emphasizes the superior membrane properties of MOFs. In this review, we present a summary of experimental and computational studies both for thin-film MOF membranes and MOF/polymer composite membranes. We aim to address opportunities and challenges related with use of MOF membranes for gas separations as well as give directions on the requirements for employing these membranes in practical applications. (C) 2015 Elsevier B.V. All rights reserved.Publication Metadata only Gas adsorption and diffusion in a highly CO2 selective metal-organic framework: molecular simulations(Taylor and Francis Ltd, 2013) N/A; Department of Chemical and Biological Engineering; Keskin, Seda; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 40548Grand canonical Monte Carlo and equilibrium molecular dynamics simulations were used to assess the performance of an rht-type metal–organic framework (MOF), Cu-TDPAT, in adsorption-based and membrane-based separation of CH4/H2, CO2/CH4 and CO2/H2 mixtures. Adsorption isotherms and self-diffusivities of pure gases and binary gas mixtures in Cu-TDPAT were computed using detailed molecular simulations. Several properties of Cu-TDPAT such as adsorption selectivity, working capacity, diffusion selectivity, gas permeability and permeation selectivity were computed and compared with well-known zeolites and MOFs. Results showed that Cu-TDPAT is a very promising adsorbent and membrane material especially for separation of CO2 and it can outperform traditional zeolites and MOFs such as DDR, MFI, CuBTC, IRMOF-1 in adsorption-based CO2/CH4 and CO2/H2 separations.Publication Metadata only The synthesis, characterization, and theoretical hydrogen gas adsorption properties of copper(II)-3,3′-thiodipropionate complexes with imidazole derivatives(Taylor and Francis Ltd, 2013) Arici, Mursel; Yesilel, Okan Zafer; Sahin, Onur; Buyukgungor, Orhan; Department of Chemical and Biological Engineering; Keskin, Seda; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 40548Three new coordination polymers, [Cu((3)-tdp)(im)(2)](n) (1), {[Cu((3)-tdp)(1-mim)(2)]0.5H(2)O}(n) (2) and {[Cu-2((3)-tdp)(2)(4-mim)(4)]H2O}(n) (3) [tdpH(2)=3,3-thiodipropionic acid, im=imidazole, 1-mim=1-methylimidazole and 4-mim=4-methylimidazole], have been prepared and characterized by spectroscopic techniques (IR and UV-Vis), elemental analyzes, magnetic measurements, thermal analyzes, and single-crystal X-ray diffraction. Complexes 1-3 crystallize in the monoclinic system with space groups of C2/c and P2(1)/c, respectively. In 1-3, tdp is a bridging ligand to form 1-D chains, which are extended into a 2-D layer by hydrogen bonding and interactions. The 3,3-thiodipropionate exhibits an unexpected coordination mode in 1-3. Simulations were used to assess the potential of the complexes in H-2 storage applications.Publication Metadata only Computational assessment of MOF membranes for CH4/H2 separations(Elsevier, 2016) N/A; Department of Chemical and Biological Engineering; Eruçar, İlknur; Keskin, Seda; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; 260094; 40548MOFs have received significant attention as gas separation membranes due to their wide range of pore sizes, permanent porosities and high surface areas. Thousands of MOFs have been reported to date. However, membrane performance of only a small number of MOFs has been experimentally reported since fabrication of thin-film MOF membranes is challenging. In this study, we used atomically-detailed simulations to assess membrane-based CH4/H-2 separation performances of 172 different MOF structures. Adsorption selectivity, diffusion selectivity, membrane selectivity and gas permeability of MOFs were calculated using atomically-detailed simulations to identify the most promising membrane materials. Our results show that a significant number of MOF membranes exhibits high CH4 selectivity over H-2 and a small number of MOF membranes exhibits mediocre H-2 selectivity over CH4. Gas permeabilities and selectivities of MOF membranes were compared with traditional membranes such as polymers and zeolites. Several MOFs were identified to exceed the upper bound established for polymeric membranes and many MOF membranes showed higher gas permeabilities and selectivities than zeolites LTA, ITQ-29 and MFI. We also carried out flexible molecular dynamics simulations to examine the effect of MOF's flexibility on the predicted membrane performance. Considering flexibility of the framework made a negligible effect on the gas permeability and selectivity of the material having large pores whereas more pronounced changes were seen in gas permeabilities of the material having narrow pores. The results of this computational study will be helpful to guide the experiments to the most promising MOF membranes for CH4/H-2 separations. (C) 2016 Elsevier B.V. All rights reserved.Publication Metadata only MOF materials as therapeutic agents, drug carriers, imaging agents and biosensors in cancer biomedicine: recent advances and perspectives(Elsevier, 2021) Bieniek, Adam; Terzyk, Artur P.; Wisniewski, Marek; Roszek, Katarzyna; Kowalczyk, Piotr; Sarkisov, Lev; Kaneko, Katsumi; Department of Chemical and Biological Engineering; Keskin, Seda; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 40548We summarize recent advances in application of MOFs as therapeutic agents, drug carriers, imaging agents and biosensors in cancer biomedicine. A holistic perspective is adopted to produce a comprehensive, critical and readable document useful to a broad community in chemistry, material science, medical fields etc. None of the previous articles adopted a holistic approach focusing on a specific disease or area, such as cancer. MOFs have a tremendous potential in cancer diagnostics and treatment. Although a new field, the amount of literature and data accumulated in this area is vast, quickly growing and requires some systematization and processing. We propose a broad overview of MOF-related literature in the treatment and diagnosis of cancer. In our study, we set: (i) to consolidate the most important and up to date information from the field of MOFs applications in medicine, particularly in anticancer therapy; and to reflect these developments in one, comprehensive study, (ii) to highlight new and emerging topics in the field, (iii) to tabulate the large number of the application examples and case studies to make the information more accessible and easy to follow, (iv) and finally, to broadly reflect on the potential of MOFs in application to cancer treatment, including the existing challenges and emerging opportunities.Publication Metadata only Metal-organic framework-based materials for the abatement of air pollution and decontamination of wastewater(PERGAMON-ELSEVIER SCIENCE LTD, 2022) Erucar, Ilknur; Heidari, Golnaz; Zare, Ehsan Nazarzadeh; Moradi, Omid; Srivastava, Varsha; Iftekhar, Sidra; Sillanpaa, Mika; N/A; N/A; Department of Chemical and Biological Engineering; Harman, Hilal Dağlar; Altıntaş, Çiğdem; Keskin, Seda; PhD Student; Researcher; Faculty Member; Department of Chemical and Biological Engineering; N/A; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 40548Developing new and efficient technologies for environmental remediation is becoming significant due to the increase in global concerns such as climate change, severe epidemics, and energy crises. Air pollution, primarily due to increased levels of H2S, SOx, NH3, NOx, CO, volatile organic compounds (VOC), and particulate matter (PM) in the atmosphere, has a significant impact on public health, and exhaust gases harm the natural sulfur, nitrogen, and carbon cycles. Similarly, wastewater discharged to the environment with metal ions, herbicides, pharmaceuticals, personal care products, dyes, and aromatics/organic compounds is a risk for health since it may lead to an outbreak of waterborne pathogens and increase the exposure to endocrine-disrupting agents. Therefore, developing new and efficient air and water quality management systems is critical. Metal-organic frameworks (MOFs) are novel materials for which the main application areas include gas storage and separation, water harvesting from the atmosphere, chemical sensing, power storage, drug delivery, and food preservation. Due to their versatile structural motifs that can be modified during synthesis, MOFs also have a great promise for green applications including air and water pollution remediation. The motivation to use MOFs for environmental applications prompted the modification of their structures via the addition of metal and functional groups, as well as the creation of heterostructures by mixing MOFs with other nanomaterials, to effectively remove haz-ardous contaminants from wastewater and the atmosphere. In this review, we focus on the state-of-the-art environmental applications of MOFs, particularly for water treatment and air pollution, by highlighting the groundbreaking studies in which MOFs have been used as adsorbents, membranes, and photocatalysts for the abatement of air and water pollution. We finally address the opportunities and challenges for the environmental applications of MOFs.Publication Metadata only Separation of CO2 mixtures using zn(bdc)(ted)0.5 membranes and composites: a molecular simulation study(amer Chemical Soc, 2011) N/A; Department of Chemical and Biological Engineering; Eruçar, İlknur; Keskin, Seda; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; 260094; 40548We used grand canonical Monte Carlo and equilibrium molecular dynamics simulations to compute adsorption isotherms and self-diffusivities of CH4/H-2 mixtures in a nanoporous metal organic framework Zn(bdc)(ted)(0.5) in our recent study (J. Phys. Chem. C 2010, 114, 13047). in this work, we extended our calculations to CO2/CH4 and CO2/H-2 mixtures by computing adsorption selectivity, diffusion selectivity, and permeation selectivity of Zn(bdc)(ted)(0.5) for these gas mixtures. Performance of several composite membranes including Zn(bdc)(ted)(0.5) as filler particles in polymer matrices was also examined for separation of CO2 from CH4 and H-2 using a combination of atomistic and continuum modeling. Results showed that adding even a small volume fraction of Zn(bdc)(ted)(0.5) into polymers can significantly enhance the gas permeability and carry the polymer/Zn(bdc)(ted)(0.5) composite membranes above the current upper bound established for pure polymer membranes.Publication Metadata only Computational investigation of dual filler-incorporated polymer membranes for efficient CO2 and H2 separation: MOF/COF/Polymer mixed matrix membranes(American Chemical Society (ACS), 2023) Erucar, Ilknur; N/A; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Aydın, Sena; Altıntaş, Çiğdem; Keskin, Seda; Master Student; Researcher; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; 40548Mixed matrix membranes (MMMs) composed of two different fillers such as metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs) embedded into polymers provide enhanced gas separation performance. Since it is not possible to experimentally consider all possible combinations of MOFs, COFs, and polymers, developing computational methods is urgent to identify the best performing MOF-COF pairs to be used as dual fillers in polymer membranes for target gas separations. With this motivation, we combined molecular simulations of gas adsorption and diffusion in MOFs and COFs with theoretical permeation models to calculate H2, N2, CH4, and CO2 permeabilities of almost a million types of MOF/COF/polymer MMMs. We focused on COF/polymer MMMs located below the upper bound due to their low gas selectivity for five industrially important gas separations, CO2/N2, CO2/ CH4, H2/N2, H2/CH4, and H2/CO2. We further investigated whether these MMMs could exceed the upper bound when a second type of filler, a MOF, was introduced into the polymer. Many MOF/COF/polymer MMMs were found to exceed the upper bounds showing the promise of using two different fillers in polymers. Results showed that for polymers having a relatively high gas permeability (>= 104 barrer) but low selectivity (<= 2.5) such as PTMSP, addition of the MOF as the second filler can have a dramatic effect on the final gas permeability and selectivity of the MMM. Property-performance relations were analyzed to understand how the structural and chemical properties of the fillers affect the permeability of the resulting MMMs, and MOFs having Zn, Cu, and Cd metals were found to lead to the highest increase in gas permeability of MMMs. This work highlights the significant potential of using COF and MOF fillers in MMMs to achieve better gas separation performances than MMMs with one type of filler, especially for H2 purification and CO2 capture applications.Publication Metadata only Atomically detailed models for transport of gas mixtures in ZIF membranes and ZIF/polymer composite membranes(amer Chemical Soc, 2012) N/A; Department of Chemical and Biological Engineering; Atcı, Erhan; Keskin, Seda; Master Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 40548In this work, we introduced atomic models for transport of single component gases (CH4, CO2, H-2, and N-2) and binary gas mixtures (H-2/CO2, H-2/N-2, H-2/CH4) in zeolite imidazolate framework (ZIF) membranes and ZIF/polymer composite membranes. the predictions of atomic models were validated by comparing with the available experimental data for a ZIF-90 membrane. Motivated from the good agreement between experimental measurements and predictions of our molecular simulations for single gas and mixture permeances, we extended atomic modeling methods to an unfabricated ZIF membrane, ZIF-65, for predicting its separation performance. Various selectivities of ZIF membranes such as ideal selectivity, mixture selectivity, Adsorption selectivity, and diffusion selectivity were computed for a wide range of operating conditions to assess the potential of ZIF membranes in H-2/CO2 separations. We then combined atomic simulations with continuum modeling to estimate the performance of ZIF-90/Matrimid and ZIF-90/Ultem composite membranes for gas separations. Our theoretical predictions agreed very well with the experimental measurements for these two composite membranes, and therefore, we assessed the performances of several ZIF/polymer membranes composed of various polymers, ZIF-90 and ZIF-65, for separation of H-2 from CO2.