Research Project: Nano-Technology Based Vacuum Insulation for Building Envelopes
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Contributors
Funders
ID
EC.00015
Authors
Erkey, Can
Faculty Member
Publications
Novel nanostructured composites of silica aerogels with a metal organic framework
(Elsevier, 2013) Erkey, Can; Eruçar, İlknur; Keskin, Seda; Ülker, Zeynep; Department of Chemical and Biological Engineering; KUTEM (Koç University Tüpraş Energy Center); Yes; College of Engineering; Research Center
Novel nanostructured composites of silica aerogel with Cu-BTC were synthesized using a slightly modified version of the conventional sol-gel method used to synthesize silica aerogels. The composite materials had monolithic structures with blue color consisting of well dispersed microporous domains of Cu-BTC in the mesoporous inorganic silica aerogel network. The Cu-BTC content in the composites ranged from 5 to 30 weight percent and the total surface area of the composites ranged from 1025 to 1138 m(2)/g. The microporosity of the composites increased with the increasing amount of Cu-BTC indicating that the micropores of Cu-BTC were accessible and functional. XRD analysis indicated that Cu-BTC retained its crystal structure in the composite despite being immersed in a solution containing water, ethanol and tetraethylorthosilicate. Additionally, it was observed that increasing Cu-BTC content caused a decrease in the average desorption pore radius with a wider pore size distribution. Nitrogen adsorption isotherms for composites could be predicted using the experimentally obtained pure component isotherm for the silica aerogel, theoretically obtained isotherm for Cu-BTC and the weight fractions of the components within the composite material.
Silylation from supercritical carbon dioxide: a powerful technique for modification of surfaces
(Kluwer Academic Publishers, 2015) Erkey, Can; Şanlı, Deniz; Department of Chemical and Biological Engineering; Yes; College of Engineering
Silylation is one of the most frequently employed surface-functionalization techniques. Silylation of surfaces from supercritical CO2 (scCO(2)) solutions, which is carried out by exposing the surface to a solution of a silane-based modifying agent dissolved in scCO(2), has been attracting increased attention due to its numerous advantages over the conventional silylation techniques which utilize liquid solutions or vapor phase. Besides being a green and environmentally friendly route, silylation using scCO(2) provides solvent-free materials after processing, enhanced diffusion and mass-transfer rates, faster reactions, homogenous and uniform surfaces, and control over the properties of the surface. Such advantages have led to many interesting studies on the development of novel scCO(2)-based silylation technologies in various fields ranging from porous materials to microelectronic processing, and from thin films to nanocomposites. In this article, we give an overview of the fundamental aspects of silylation from scCO(2) and summarize the studies in the literature in various fields.
Experimental and theoretical investigation of supercritical drying of silica alcogels
(Elsevier, 2015) Erkey, Can; Özbakır, Yaprak; N/A; Department of Chemical and Biological Engineering; Yes; College of Engineering
Extraction of ethanol from pores of cylindrical silica alcogel samples using supercritical CO2 (scCO(2)) in a tubular extraction vessel was investigated both by experiments and simulations. Partial differential equations representing mass transfer within the cylindrical silica alcogel phase and in the external scCO(2) phase were developed and solved using finite difference method. the percent removal data as a function of time were found to be in good agreement with model results using mass transfer coefficients regressed from the experimental data. the mass transfer coefficients were found to be higher by about a factor of three from two of the correlations tested which were developed for supercritical extraction. Effect of scCO(2) flow rate on the drying was investigated through experiments and simulations. increasing flow rate led to a decrease in effluent concentration at a specific time but did not significantly affect rate of extraction of ethanol. Effects of the magnitude of the effective diffusion coefficient and alcogel thickness on drying were investigated through simulations. Drying time of the alcogel decreased with decreasing gel thickness and increasing effective diffusion coefficient.
Monolithic composites of silica aerogel with poly(methyl vinyl ether) and the effect of polymer on supercritical drying
(Elsevier, 2015) Erkey, Can; Özbakır, Yaprak; Ülker, Zeynep; N/A; Department of Electrical and Electronics Engineering; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; KUTEM (Koç University Tüpraş Energy Center); Yes; College of Engineering; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING; Research Center
Novel monolithic and crack-free poly(methyl vinyl ether) (PMVE)-silica aerogel composites were synthesized using a modified sol gel procedure. The presence of PMVE in solid network of the composite samples was confirmed by a variety of techniques including IR spectroscopy, TGA and BET. Extraction of ethanol from alcogel composite rods using scCO(2) was investigated both by experiments and simulations. Partial differential equations representing mass transfer within the composite alcogel phase and in the flowing scCO(2) phase were developed and solved using finite difference method. Mass of ethanol removed from the samples as a function of time were found to be in good agreement with model results using mass transfer coefficients regressed from the experimental data. Effect of the polymer content on the drying could be estimated by taking into account of porosity change with polymer incorporation. Drying time of the alcogel increased with increasing weight fraction of polymer in the silica network and gel thickness.
