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Publication Metadata only Advances in constraint theories of rubber-like elasticity of polymers(Pergamon-Elsevier Science Ltd, 2010) Department of Chemical and Biological Engineering; Erman, Burak; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 179997Advances in the constraint theories of rubber elasticity during the past few years, based on the constrained junction, tube, and slip-link models, are cited and discussed. (C) 2009 Elsevier Ltd. All rights reserved.Publication Metadata only Development of highly stable and luminescent aqueous CdS quantum dots with the poly(acrylic acid)/mercaptoacetic acid binary coating system(Amer Scientific Publishers, 2009) Lieberwirth, I.; Department of Chemistry; N/A; Department of Chemical and Biological Engineering; Acar, Havva Funda Yağcı; Çelebi, Serdar; Serttunalı, Nazlı İpek; Faculty Member; Master Student; Undergraduate Student; Department of Chemistry; Department of Chemical and Biological Engineering; College of Sciences; Graduate School of Sciences and Engineering; College of Engineering; 178902; N/A; N/AHighly stable and luminescent CdS quantum dots (QD) were prepared in aqueous solutions via in situ capping of the crystals with the poly(acrylic acid) (PAA) and mercaptoacetic acid (MAA) binary mixtures. The effect of reaction temperature and coating composition on the particle size, colloidal stability and luminescence were investigated and discussed in detail. CdS QDs coated with either PAA or MAA were also prepared and compared in terms of properties. CdS-MAA QDs were highly luminescent but increasing reaction temperature caused an increase in the crystal size and a significant decrease in the quantum yield (QY). Although less luminescent and bigger than CdS-MAA, CdS-PAA QDs maintained the room temperature size and QY at higher reaction temperatures. CdS-MAA QDs lacked long term colloidal stability whereas CdS-PAA QDs showed excellent stability over a year. Use of PAA/MAA mixture as a coating for CdS nanoparticles during the synthesis provided excellent stability, high QY and ability to tune the size and the color of the emission. Combination of all of these properties can be achieved only with the mixed coating. CdS coated with PAA/MAA at 40/60 ratio displayed the highest QY (50% of Rhodamine B) among the other compositions.Publication Metadata only Towards complete elucidation of structural factors controlling thermal stability of il/mof composites: effects of ligand functionalization on mofs(Iop Publishing Ltd, 2020) N/A; Department of Chemical and Biological Engineering; N/A; N/A; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Durak, Özce; Kulak, Harun; Kavak, Safiyye; Polat, Hüsamettin Mert; Keskin, Seda; Uzun, Alper; Master Student; Researcher; Researcher; Researcher; 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; College of Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; N/A; 40548; 59917In this work, we incorporated an ionic liquid (IL), 1-n-butyl-3-methylimidazolium methyl sulfate ([BMIM][MeSO4]) into two different metal organic frameworks (MOFs), UiO-66, and its amino-functionalized counterpart, NH2-UiO-66, to investigate the effects of ligand-functionalization on the thermal stability limits of IL/MOF composites. The as-synthesized IL/MOF composites were characterized in detail by combining x-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller analysis, x-ray fluorescence, infrared spectroscopies (FTIR), and their thermal stability limits were determined by thermogravimetric analysis (TGA). Characterization data confirmed the successful incorporation of the IL into each MOF and indicated the presence of direct interactions between them. A comparison of the interactions in [BMIM][MeSO4]-incorporated UiO-66 and NH2-UiO-66 with those in their 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6])-incorporated counterparts showed that the hydrophilic IL, [BMIM][MeSO4], interacts with the 1,4-benzenedicarboxylate (BDC) ligand of the UiO-66, while the hydrophobic IL, [BMIM][PF6], is interacting with the joints where zirconium metal cluster coordinates with BDC ligand. The TGA data demonstrated that the composite with the ligand-functionalized MOF, NH2-UiO-66, exhibited a lower percentage decrease in the maximum tolerable temperature compared to those of IL/UiO-66 composites. Moreover, it is discovered that when the IL is hydrophilic, its hydrogen bonding ability can be utilized to designate an interaction site on MOF's ligand structure, leads to a lower reduction in thermal stability limits. These results provide insights for the rational design of IL/MOF composites and contribute towards the complete elucidation of structural factors controlling the thermal stability.Publication Metadata only Tuning adsorption, structure and compressive strength of sepiolite- and metakaolin-based alkali activated monoliths for methylene blue removal from waste water(Elsevier, 2022) Kaya-Ozkiper, Kardelen; Soyer-Uzun, Sezen; Department of Chemical and Biological Engineering; Uzun, Alper; 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); College of Engineering; 59917Adsorption is considered as the most beneficial waste water treatment method when compared to other physical, chemical, and biological treatment methods due to its economic feasibility, environmentally friendliness, and easy implementation. Alkali activated materials (AAMs) are promising materials as adsorbents for removing organic molecules from waste water owing to their low cost and availability, easy and environmentally-friendly synthesis, high adsorption capacity, chemical stability, regeneration/reusability capability, and high mechanical strength. Unfortunately, powder-formed adsorbents are mostly focused in literature although their practical utilization is limited due to problems in recovery, regeneration and mechanical performance. In this regard, a family of sepiolite (S)-and metakaolin (M)-based alkali activated monoliths (S-Monolith and M-Monolith) with varying porosities were synthesized and tested for methylene blue (MB) adsorption comparatively for the first time. Hydrogen peroxide (H2O2) is used as a foaming agent to adjust the porosity with varying concentrations in the ranges of 0-8 wt% and 0-1 wt%, for S-Monoliths and M-Monoliths, respectively. As porosity of S-Monoliths increases from 13% to 40%, MB uptake capacity rises from 6.6 to 10.3 mg g-1 while corresponding compressive strength values decrease gradually from 37 MPa to 6.5 MPa. On the other hand, as the porosity of M-Monoliths varies from 31.9% to 63.5%, corresponding MB uptake capacity increases from 4.3 to 7.8 mg s(-1 )whereas compressive strength values decrease from 28 MPa to 2.1 MPa. Both pseudo-first-order and pseudo-second-order adsorption kinetics show good fit to the experimental data, indicating that both physical and chemical adsorption processes govern the adsorption process. Adsorption isotherm model studies showed that Langmuir isotherm provides a better fit indicating that chemisorption controls the adsorption mechanism. Regeneration experiments conducted on samples with the highest porosities show that S-and M-Monoliths can be regenerated up to four cycles without loss in their integrity. Results show that the adsorption performance of AAM monoliths synthesized from different raw materials can be tuned by changing the porosity levels and these monoliths offer me-chanically strong and sustainable options as adsorbents for industrial applications.Publication Metadata only Two novel 2D and 3D coordination polymers constructed from pyrazine-2,3-dicarboxylic acid and chloride bridged secondary building units(Elsevier Science Sa, 2011) Gunay, Gunes; Yesilel, Okan Zafer; Soylu, Mustafa Serkan; Dal, Hakan; Department of Chemical and Biological Engineering; Keskin, Seda; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 40548The synthesis, spectroscopic properties and crystal structures of {[Cu-2(mu-Cl)(2)(mu(3)-Hpzdc)(Cl)(H2O)(2)]center dot 1.5H(2)O}(n) (1) and {[Cd(mu-Cl)(mu-Hpzdc)]center dot H2O)}(n) (2) complexes were reported (H(2)pzdc = pyrazine-2,3-dicarboxylic acid). H(2)pzdc is singly deprotonated in both complexes and the coordination mode of Hpzdc ligand in 1 has been first reported in this presentation. The complex 1, which has a 3D framework structure, was formed with double mu-chloride and mu(3)-Hpzdc bridges. In 1, water molecules occupy in the 1D channel as guest molecules. Furthermore, unprecedented 1D hybrid water-chloride anionic [(H2O)(8)Cl-2](n) cluster has been structurally identified. In the complex 2, the Cd(II) atom is seven-coordinated by two hydrogen pyrazine-2,3-dicarboxylate, two chloride and one aqua ligands in a distorted monocapped octahedral coordination geometry. The Cd(II) atoms are bridged by the bis(bidentate) Hpzdc ligands, forming 1D polymer chain. The adjacent 10 chains are linked each other through the double chloride bridges to form 20 layer. The layers are connected together through O-H center dot center dot center dot O interactions resulting in a three-dimensional framework. The mechanisms for these compounds were validated by density functional theory (DFT) calculations on the experimental geometries. The photoluminescent property of 2 was investigated in the solid state at room temperature. Moreover, in order to assess the potentials of 1 and 2 in gas storage applications, we performed atomically detailed simulations.