Researcher:
Balci, Volkan

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PhD Student

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Volkan

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Balci

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Balci, Volkan

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2014 - 20163

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Researcher Of Publications: search.filters.isAuthorOfPublication.aa27629d-e3ab-4570-8adb-e6e44e8be565

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    Structural factors controlling thermal stability of imidazolium ionic liquids with 1-N-butyl-3-methylimidazolium cation on gamma-Al2O3
    (Elsevier, 2014) N/A; N/A; Department of Chemical and Biological Engineering; Akçay, Aslı; Balci, Volkan; Uzun, Alper; Master Student; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 59917
    Structural factors determining thermal stability limits of imidazolium ionic liquids (ILs) with 1-n-butyl-3-methylimidazolium, [BMIM](+), cation on one of the most commonly used metal-oxide support, gamma-Al2O3, were determined by thermogravimetric analysis complemented by infrared (IR) spectroscopy. IR results show that inter-ionic interaction strength in ILs increases as their anion structure varies in the following order: [NTf2](-) < [SbF6](-) < [BE4](-) < [TfO](-) < [OS](-) < [HSO4](-) < [TOS](-) < [DBP](-) < [OAc](-). TGA data illustrate a strong dependence of thermal stability limits on inter-ionic interactions. Thermal stability limits of both bulk and gamma-Al2O3-supported [BMIM](+)-based ILs increase with decreasing inter-ionic interaction strength. Thermal stability limit of IL with octyl sulfate anion was lower than that of analogous IL with hydrogen sulfate anion, because of its exceptionally large anion size. Moreover, the effect of gamma-Al2O3 on IL thermal stability conditions becomes dominant with decreasing inter-ionic interactions in ILs. (C) 2014 Elsevier B.V. All rights reserved.
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    Understanding spectroscopic features of trihexyltetradecylphosphonium chloride
    (Wiley-V C H Verlag Gmbh, 2016) N/A; Department of Chemical and Biological Engineering; Balci, Volkan; Uzun, Alper; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 59917
    A comprehensive structural and spectroscopic characterization of trihexyltetradecylphosphonium chloride, [P-666(14)][Cl], was conducted by combining experiments with density functional theory (DFT) calculations. The structure of [P-666(14)][Cl] was first characterized experimentally by IR and NMR spectroscopies. Then, conformer search was performed by DFT calculations at B3LYP/6-31+ G(d) level to elucidate the molecular structure and intermolecular interactions prevailing in the [P-666(14)][Cl]. Vibrational and 1HNMR spectra computed on the most stable conformer geometry were used to identify the features in the experimental spectroscopic data. Results revealed that experimental IR and NMR spectra correlated very well with the corresponding computational spectra confirming that the DFT-optimized equilibrium geometry of the most-stable conformer represents a probable analogue to the experimental conformation. Consequently, hydrogen bonds between [CI](-) and three alpha-hydrogens of [P-666(14)]+ closest to the anion were identified by Natural Bond Orbital (NBO) analysis confirmed by the shifts in the corresponding IR bands.
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    A model to predict maximum tolerable temperatures of metal-oxide-supported 1-n-butyl-3-methylimidazolium based ionic liquids
    (Elsevier, 2015) N/A; N/A; N/A; Department of Chemical and Biological Engineering; Akçay, Aslı; Babucci, Melike; Balci, Volkan; Uzun, Alper; Master Student; PhD Student; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 59917
    The thermal stability limits of metal-oxide-supported ionic liquids (Its) with 1-n-butyl-3-methylimidazolium cation, [BMIM](+), on most commonly used metal-oxides, SiO2, TiO2, gamma-Al2O3, and MgO are determined. Data show that stability limits of bulk and metal-oxide-supported ILs linearly increase with increasing acidity of C2 proton on imidazolium ring, controlling the inter-ionic interaction strength. Moreover, data also show that the presence of metal-oxide lowers the stability limits considerably. This effect becomes more significant as the surface acidity of the metal-oxide decreases from SiO2 to MgO This decrease in stability limits with increasing point of zero charge (PZC) of metal-oxide indicates that the interaction between IL and metal-oxide becomes the dominant factor rather than the inter-ionic interactions. Based on these findings a simple mathematical expression was developed as a function of PZC and inter-ionic interaction strength probed by nu(C2H) to predict the stability limits of [BMIM](+)-based ILs immobilized on metal-oxides. Performance of the model was tested on several different ILs supported on different metal-oxides, including Fe2O3 and CeO2. Results show that the model successfully predicts the maximum operating or tolerable temperatures of supported-[BMIM](+)-based ILs with an average relative error less than 4.3%. We suggest that the model developed here can help to choose proper ILs that can tolerate the operating conditions of systems including ILs immobilized on metal oxides, such as in solid catalysts with ionic liquid layer (SCILL) or in supported ionic liquid phase (SILP) catalysts. (C) 2014 Elsevier Ltd. All rights reserved.