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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/6
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Publication Open Access Database for CO2 separation performances of MOFs based on computational materials screening(American Chemical Society (ACS), 2018) Eruçar, İlknur; Department of Chemical and Biological Engineering; Altıntaş, Çiğdem; Avcı, Gökay; Harman, Hilal Dağlar; Azar, Ayda Nemati Vesali; Velioğlu, Sadiye; Keskin, Seda; Researcher; Post Doctorate Student; Department of Chemical and Biological Engineering; College of Engineering; N/A; N/A; N/A; N/A; N/A; 40548Metal-organic frameworks (MOFs) are potential adsorbents for CO2 capture. Because thousands of MOFs exist, computational studies become very useful in identifying the top performing materials for target applications in a time-effective manner. In this study, molecular simulations were performed to screen the MOF database to identify the best materials for CO2 separation from flue gas (CO2/N-2) and landfill gas (CO2/CH4) under realistic operating conditions. We validated the accuracy of our computational approach by comparing the simulation results for the CO2 uptakes, CO2/N-2 and CO2/CH4 selectivities of various types of MOFs with the available experimental data. Binary CO2/N-2 and CO2/CH4 mixture adsorption data were then calculated for the entire MOF database. These data were then used to predict selectivity, working capacity, regenerability, and separation potential of MOFs. The top performing MOF adsorbents that can separate CO2/N-2 and CO2/CH4 with high performance were identified. Molecular simulations for the adsorption of a ternary CO2/N-2/CH4 mixture were performed for these top materials to provide a more realistic performance assessment of MOF adsorbents. The structure-performance analysis showed that MOFs with Delta Q(st)(0) > 30 kJ/mol, 3.8 angstrom < pore-limiting diameter < 5 angstrom, 5 angstrom < largest cavity diameter < 7.5 angstrom, 0.5 < phi < 0.75, surface area < 1000 m(2)/g, and rho > 1 g/cm(3) are the best candidates for selective separation of CO2 from flue gas and landfill gas. This information will be very useful to design novel MOFs exhibiting high CO2 separation potentials. Finally, an online, freely accessible database https://cosmoserc.ku.edu.tr was established, for the first time in the literature, which reports all of the computed adsorbent metrics of 3816 MOFs for CO2/N-2, CO2/CH4, and CO2/N-2/CH4 separations in addition to various structural properties of MOFs.Publication Open Access Plasmon-coupled photocapacitor neuromodulators(American Chemical Society (ACS), 2020) Ülgüt, Burak; Çetin, Arif E.; N/A; N/A; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; Department of Chemical and Biological Engineering; Melikov, Rustamzhon; Srivastava, Shashi Bhushan; Karatüm, Onuralp; Doğru-Yüksel, Itır Bakış; Jalali, Houman Bahmani; Sadeghi, Sadra; Dikbaş, Uğur Meriç; Kavaklı, İbrahim Halil; Nizamoğlu, Sedat; PhD Student; Researcher; PhD Student; PhD Student; Master Student; Faculty Member; Faculty Member; Department of Molecular Biology and Genetics; Department of Electrical and Electronics Engineering; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Engineering; N/A; N/A; N/A; N/A; N/A; N/A; N/A; 40319; 130295Efficient transduction of optical energy to bioelectrical stimuli is an important goal for effective communication with biological systems. For that, plasmonics has a significant potential via boosting the light-matter interactions. However, plasmonics has been primarily used for heat-induced cell stimulation due to membrane capacitance change (i.e., optocapacitance). Instead, here, we demonstrate that plasmonic coupling to photocapacitor biointerfaces improves safe and efficacious neuromodulating displacement charges for an average of 185% in the entire visible spectrum while maintaining the faradic currents below 1%. Hot-electron injection dominantly leads the enhancement of displacement current in the blue spectral window, and the nanoantenna effect is mainly responsible for the improvement in the red spectral region. The plasmonic photocapacitor facilitates wireless modulation of single cells at three orders of magnitude below the maximum retinal intensity levels, corresponding to one of the most sensitive optoelectronic neural interfaces. This study introduces a new way of using plasmonics for safe and effective photostimulation of neurons and paves the way toward ultrasensitive plasmon-assisted neurostimulation devices.Publication Open Access High-yield production of biohybrid microalgae for on-demand cargo delivery(Wiley, 2020) Akolpoğlu, Mukrime Birgul; Bozüyük, Uğur; Ceylan, Hakan; Department of Chemical and Biological Engineering; Department of Mechanical Engineering; Kızılel, Seda; Doğan, Nihal Olcay; Sitti, Metin; Faculty Member; Faculty Member; Department of Chemical and Biological Engineering; Department of Mechanical Engineering; College of Engineering; Graduate School of Sciences and Engineering; School of Medicine; 28376; N/A; 297104Biohybrid microswimmers exploit the swimming and navigation of a motile microorganism to target and deliver cargo molecules in a wide range of biomedical applications. Medical biohybrid microswimmers suffer from low manufacturing yields, which would significantly limit their potential applications. In the present study, a biohybrid design strategy is reported, where a thin and soft uniform coating layer is noncovalently assembled around a motile microorganism.Chlamydomonas reinhardtii(a single-cell green alga) is used in the design as a biological model microorganism along with polymer-nanoparticle matrix as the synthetic component, reaching a manufacturing efficiency of approximate to 90%. Natural biopolymer chitosan is used as a binder to efficiently coat the cell wall of the microalgae with nanoparticles. The soft surface coating does not impair the viability and phototactic ability of the microalgae, and allows further engineering to accommodate biomedical cargo molecules. Furthermore, by conjugating the nanoparticles embedded in the thin coating with chemotherapeutic doxorubicin by a photocleavable linker, on-demand delivery of drugs to tumor cells is reported as a proof-of-concept biomedical demonstration. The high-throughput strategy can pave the way for the next-generation generation microrobotic swarms for future medical active cargo delivery tasks.Publication Open Access Fast and selective adsorption of methylene blue from water using [BMIM][PF6]-incorporated UiO-66 and NH2-UiO-66(American Chemical Society (ACS), 2020) Department of Chemical and Biological Engineering; N/A; Kulak, Harun; Keskin, Seda; Uzun, Alper; Kavak, Safiyye; Polat, Hüsamettin Mert; 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; College of Engineering; N/A; 40548; 59917; N/A; N/AIncorporation of ionic liquids (ILs) into metal-organic frameworks (MOFs) offers a broad potential in various applications. However, their applications in wastewater treatment have remained unexplored. Here, we investigate their potential in wastewater treatment and demonstrate a new concept of IL incorporation in ligand-functionalized MOFs, introducing IL/FMOFs. The composites were prepared by incorporating 1-n-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF6], into UiO-66 and NH2-UiO-66 and tested for the adsorption of methylene blue (MB) and methyl orange (MO) from aqueous solutions. Data showed that NH2-functionalization and [BMIM][PF6] incorporation improved MB removal performance of UiO-66 by 16- and 48-times, as the capacity increased from 84.8 to 144.7 mg g(-1) and 174.1 mg g(-1), respectively. When considering both modifications together, [BMIM][PF6]/NH2-UiO-66 was almost 300 times faster than that of UiO-66, and the capacity exceeded 200 mg g(-1). Data further suggested that IL incorporation almost doubled MB/MO selectivity because of the strong electrostatic interactions and hydrogen bonding between [PF6](-) and MB, and pi-pi interactions between the [BMIM](+) cation and MB molecules. These results are the first to demonstrate the prospect of combining ligand functionalization with IL incorporation for modifying MOFs, introducing IL/FMOF composites for fast and selective removal of pollutants from wastewater.Publication Open Access High-throughput computational screening of the metal organic framework database for CH4/H-2 separations(American Chemical Society (ACS), 2018) Eruçar, İlknur; Department of Chemical and Biological Engineering; Altıntaş, Çiğdem; Keskin, Seda; Researcher; Department of Chemical and Biological Engineering; College of Engineering; N/A; 40548Metal organic frameworks (MOFs) have been considered as one of the most exciting porous materials discovered in the last decade. Large surface areas, high pore volumes, and tailorable pore sizes make MOFs highly promising in a variety of applications, mainly in gas separations. The number of MOFs has been increasing very rapidly, and experimental identification of materials exhibiting high gas separation potential is simply impractical. High throughput computational screening studies in which thousands of MOFs are evaluated to identify the best candidates for target gas separation is crucial in directing experimental efforts to the most useful materials. In this work, we used molecular simulations to screen the most complete and recent collection of MOFs from the Cambridge Structural Database to unlock their CH4/H-2 separation performances. This is the first study in the literature, which examines the potential of all existing MOFs for adsorption-based CH4/H-2 separation. MOFs (4350) were ranked based on several adsorbent evaluation metrics including selectivity, working capacity, adsorbent performance score, sorbent selection parameter, and regenerability. A large number of MOFs were identified to have extraordinarily large CH4/H-2 selectivities compared to traditional adsorbents such as zeolites and activated carbons. We examined the relations between structural properties of MOFs such as pore sizes, porosities, and surface areas and their selectivities. Correlations between the heat of adsorption, adsorbility, metal type of MOFs, and selectivities were also studied. On the basis of these relations, a simple mathematical model that can predict the CH4/H-2 selectivity of MOFs was suggested, which will be very useful in guiding the design and development of new MOFs with extraordinarily high CH4/H-2 separation performances.Publication Open Access High-throughput molecular simulations of metal organic frameworks for CO2 separation: opportunities and challenges(Frontiers, 2018) Eruçar, İlknur; Department of Chemical and Biological Engineering; Keskin, Seda; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 40548Metal organic frameworks (MOFs) have emerged as great alternatives to traditional nanoporous materials for CO2 separation applications. MOFs are porous materials that are formed by self-assembly of transition metals and organic ligands. The most important advantage of MOFs over well-known porous materials is the possibility to generate multiple materials with varying structural properties and chemical functionalities by changing the combination of metal centers and organic linkers during the synthesis. This leads to a large diversity of materials with various pore sizes and shapes that can be efficiently used for CO2 separations. Since the number of synthesized MOFs has already reached to several thousand, experimental investigation of each MOF at the lab-scale is not practical. High-throughput computational screening of MOFs is a great opportunity to identify the best materials for CO2 separation and to gain molecular-level insights into the structure-performance relationships. This type of knowledge can be used to design new materials with the desired structural features that can lead to extraordinarily high CO2 selectivities. In this mini-review, we focused on developments in high-throughput molecular simulations of MOFs for CO2 separations. After reviewing the current studies on this topic, we discussed the opportunities and challenges in the field and addressed the potential future developments.Publication Open Access A remarkable class of nanocomposites: aerogel supported bimetallic nanoparticles(Frontiers, 2020) Özbakır, Yaprak; Department of Chemical and Biological Engineering; Güneş, Hande; Barım, Şansım Bengisu; Yousefzadeh, Hamed; Bozbağ, Selmi Erim; Erkey, Can; Researcher; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; N/A; 29633Aerogels are a unique class of materials due to their low density, high porosity, high surface area, and an open and interconnected pore structure. Aerogels can be organic, inorganic and hybrid with a plethora of surface chemistries. Aerogel-based products for thermal insulation are already in the market and many studies are being conducted in many laboratories around the world to develop aerogel-based products for other applications including catalysis, adsorption, separations, and drug delivery. On the other hand, bimetallic nanoparticles dispersed on high surface area carriers, which have superior properties compared to their monometallic counterparts, are used or are in development for a wide variety of applications in catalysis, optics, sensing, detection, and medicine. Investigations on using aerogels as high surface area carriers for dispersing bimetallic nanoparticles are leading to development of new composite materials with outstanding properties due to the remarkable properties of aerogels. The review focuses on the techniques to synthesize these materials, their properties, the techniques to tune their pore properties and surface chemistry and the applications of these materials.Publication Open Access Computational investigation of multifunctional MOFs for adsorption and membrane-based separation of CF4/CH4, CH4/H-2, CH4/N-2, and N-2/H-2 mixtures(Royal Society of Chemistry (RSC), 2023) Department of Chemical and Biological Engineering; Keskin, Seda; Demir, Hakan; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 40548; N/AThe ease of functionalization of metal-organic frameworks (MOFs) can unlock unprecedented opportunities for gas adsorption and separation applications as the functional groups can impart favorable/unfavorable regions/interactions for the desired/undesired adsorbates. In this study, the effects of the presence of multiple functional groups in MOFs on their CF4/CH4, CH4/H-2, CH4/N-2, and N-2/H-2 separation performances were computationally investigated combining grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. The most promising adsorbents showing the best combinations of selectivity, working capacity, and regenerability were identified for each gas separation. 15, 13, and 16 out of the top 20 MOFs identified for the CH4/H-2, CH4/N-2, and N-2/H-2 adsorption-based separation, respectively, were found to have -OCH3 groups as one of the functional groups. The biggest improvements in CF4/CH4, CH4/H-2, CH4/N-2, and N-2/H-2 selectivities were found to be induced by the presence of -OCH3-OCH3 groups in MOFs. For CH4/H-2 separation, MOFs with two and three functionalized linkers were the best adsorbent candidates while for N-2/H-2 separation, all the top 20 materials involve two functional groups. Membrane performances of the MOFs were also studied for CH4/H-2 and CH4/N-2 separation and the results showed that MOFs having -F-NH2 and -F-OCH3 functional groups present the highest separation performances considering both the membrane selectivity and permeability.Publication Open Access The role and applications of aerogels in textiles(Hindawi, 2022) Azam, Farooq; Ahmad, Faheem; Ülker, Zeynep; Zafar, Muhammad Sohail; Ahmad, Sheraz; Rasheed, Abher; Nawab, Yasir; Department of Chemical and Biological Engineering; Erkey, Can; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 29633Textiles have been used for clothing purposes since ancient times. However, due to their functional properties, their importance-as well as their use in various fields such as filtration, protective clothing, and medical applications-increased over time. Properties of the textile fabrics depend mostly on the fiber type, fabrication technique, and structure. Moreover, fabric porosity is one of the properties that provide comfort, increased thermal insulation, and filtration capability to the end products. The porous structure of woven, knitted, and nonwoven fabrics has been used for many years to get the desired porosity. Usually, macroporous structures are achieved using these types of textiles. Electrospinning is used to produce nanoporous textile fibrous web, but its poor mechanical properties and low production rate limit its use. Aerogels are solid materials with ultrahigh porosity at the nanoscale with low density and good thermal insulation properties, due to which they are considered potential insulation materials today. On the other hand, pure aerogels are sometimes brittle and have poor mechanical properties. Thus, they cannot be directly used in various applications. Consequently, textile reinforced aerogel composites have been developed, which could provide flexibility and strength to aerogels and impart nanoporous structure to textiles. This review summarizes conventional techniques to produce the porous structure in textiles followed by the modern techniques to develop a nanoporous structure. Further, different mechanisms to synthesize textile reinforced aerogel composites are discussed to get a nanoporous structure for filtration and thermal insulation applications. The porosity, mechanical properties, and thermal insulation of textile reinforced aerogel composites are also highlighted. In the end, we give a conclusion that not only summarizes the literature, but also includes recommendations for the researchers.