Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 5Citation - Scopus: 6Use, Preparation, and Characterization of Copper-Containing Silica Gel(American Chemical Society, 2020) Ulutan, Sevgi; Tüzüm Demir, Ayşe Pınar; Balköse, DevrimThe preparation and characterization of humidity-indicating silica gel containing copper sulfate were aimed at in the present study. The equilibrium and kinetics of Cu(II) sorption were investigated by contacting 200-1600 mg dm(-3) Cu ion-containing solutions with silica hydrogel slabs having 10% silica. The diffusion coefficient of Cu(II) in silica hydrogel was determined to be on the order of 10(-10) m(2) s(-1). X-ray diffraction indicated that the gels contained mainly CuSO4 center dot 3H(2)O, CuSO4 center dot H2O, and small amounts of CuSO4 and CuSiO3 center dot 2H(2)O. The silica gel with Cu(II) can be used as a humidity indicator since its color changes from light blue to dark blue upon moisture adsorption.Article Citation - WoS: 5Citation - Scopus: 5Methylene Blue Adsorption From Aqueous Solutions To Flexible Poly(vinyl Chloride) Silica Composites(John Wiley and Sons Inc., 2015) Yetgin, Senem; Ulutan, Sevgi; Balköse, DevrimMethylene blue (MB) adsorption studies were performed with poly(vinyl chloride)-(dioctyl phthalate)-silica composites, which were obtained by using plastisol-plastigel technology. The films were flexible, having elastic modulus of 1.0-1.5 GPa. Diminishing MB concentration in the aqueous phase was followed as the adsorption process advanced by using visible spectroscopy. Contributions of the individual components of the composites to adsorption were also investigated. Although the MB adsorption capacity was extensively high for silica, it was moderate for the composite, most likely owing to the occlusion of pores of silica by plasticizer to some extent. The improvement of MB adsorption capacity of the composites as the silica ratio increased was explicitly deduced from the optical microscopy photographs. The diffusion coefficients of MB through the composites were 5 × 10-13, 6 × 10-13, and 3 × 10-13 m2 s-1 with regression coefficients of 0.73, 0.89, and 0.88 for 0, 2, and 16% silica-containing composites, respectively. Because of the slow diffusion of MB in poly(vinyl chloride)-silica composites, using them as dynamic column adsorbent was not practical. However, these versatile plastics can be used as plastic labels, colored clothing, leather substitutes, antimicrobial medical devices, and laser printable surfaces.Article Citation - WoS: 1Citation - Scopus: 1Flexible Pvc-Silica Composites as an Adsorptive Material for Water Soluble Dyes(Smithers Rapra Technology, 2013) Ulutan, Sevgi; Yetgin, Senem; Balköse, DevrimMethylene Blue (MB) adsorption studies were performed on flexible Polyvinyl Chloride/Silica composites which were obtained by using plastisol-plastigel technology. Change of MB concentration in aqueous phase as the adsorption process advanced was followed by using visible spectroscopy. The diffusion of MB through the composites exhibited non-Fickian behavior with a diffusivity of 10-11 m2s-1. Making use of such PVC-silica composite sheets as column packing, the packing time will be reduced and the surface available for diffusion will be increased. © 2013 Smithers Rapra Technology.Conference Object Citation - WoS: 22Citation - Scopus: 24Characterization of Poly(vinyl Chloride) Powder Produced by Emulsion Polymerization(Springer Verlag, 2010) Atakul Savrık, Sevdiye; Balköse, Devrim; Ulutan, Sevgi; Ülkü, SemraThe effect of emulsion process formulation ingredients on the morphology, structure, and properties of polyvinyl chloride (PVC) powder has been considered in this study. PVC powder was extracted with ethanol and films were obtained by solvent casting from tetrahydrofurane. Characterization of powders, films, and ethanol extract was performed through FTIR spectroscopy, DSC, AFM, SEM, EDX analysis, methylene blue, and nitrogen adsorption. PVC powder was composed of spheres of a large particle size range from 10 nm to 20 μm as shown by SEM. The specific surface area of the PVC powder was determined as 16 and 12 m 2 g-1 from methylene blue adsorption at 25 °C and from N2 adsorption at -196 °C, respectively. AFM indicated the surface roughness of the films obtained by pressing the particles was 25.9 nm. Density of PVC powder was determined by helium pycnometry as 1.39 g cm -3. FTIR spectroscopy indicated that it contained carbonyl and carboxylate groups belonging to additives such as surface active agents, plasticizers, and antioxidants used in production of PVC. These additives were 1.6% in mass of PVC as determined by ethanol extraction. EDX analysis showed PVC particles surfaces were coated with carbon-rich materials. The coatings had plasticizer effect since, glass transition temperature was lower than 25 °C for PVC powder and it was 80 °C for ethanol extracted powders as found by using differential scanning calorimetry. These additives from polymerization process made PVC powder more thermally stable as understood from Metrom PVC thermomat tests as well. © 2010 Akadémiai Kiadó, Budapest, Hungary.Article Citation - WoS: 8Citation - Scopus: 8Water Vapour Adsorption on Organic and Inorganic Polymers(Springer Verlag, 2003) Balköse, Devrim; Özkan, Fehime; Ulutan, Sevgi; Ülkü, SemraWater vapour adsorption on polymers affects their processing behaviour and useful properties. Water vapour adsorption on organic polymers, silk, Nylon 6 fibres in undrawn and permanent set forms, polyester micro fibres, plasticised PVC films with 60 phr dioctylphthalate (OOP) and inorganic polymer sepiolite particles were investigated in this study. The materials were examined using the BET equation. The surface areas of silk, cast Nylon 6 and muss Nylon 6 were determined as 108, 46 and 23 m2 g-1, respectively. Sepiolite did not fit BET equation. Polyester and PVC adsorbed very small amounts of moisture.Article Citation - WoS: 47Citation - Scopus: 49Characterization of Hollow Chemical Garden Fibers From Metal Salts and Water Glass(Springer Verlag, 2002) Balköse, Devrim; Özkan, Fehime; Köktürk, Uğur; Ulutan, Sevgi; Ülkü, Semra; Nişli, GürelHollow fibers formed from water glass and metal salts of IIA(Ca), VIIB(Fe, Co, Ni) and IB(Cu) groups were characterised in this study. Fragile fibres obtained herein broke down into small pieces during isolation and drying. Quantitative information about morphology, chemical composition and surface structure of the fibres were obtained. The diameter and wall thickness of the fibers were around 50 μ and 3 μ. respectively. They had particulate inner and smooth outer surfaces. Fibers had variable composition with metal (II) oxide/SiO2 ratio in the range 0.31 to 1.02. While group VIIB metal (II) fibres were amorphous, group IIA and IB metal (II) fibers were partially crystalline All the fibres had pores both in micro pore and meso pore region. The B.E.T. surface area fron N2 adsorption data was in the range of 10-249 m3 g-1 and 8-176 m2 g-1 from Langmuir an B.E.T. models respectively.Article Citation - WoS: 12Citation - Scopus: 17Dynamics of Water Vapor Adsorption on Humidity-Indicating Silica Gel(Elsevier Ltd., 1998) Balköse, Devrim; Ulutan, Sevgi; Çakıcıoğlu Özkan, Seher Fehime; Çelebi, Sedat; Ülkü, SemraWell-defined CoCl2-containing silica gels were prepared by impregnation of the aqueous solution of the salt to silica hydrogel, drying and aging methods. Silica gels having 392-437 m2 g-1 surface area and 0.21-0.37 cm3 g-1 pore volume and having an average particle size of 3 mm were obtained. Aging in CoCl2 solutions decreased the surface area of silica gels from 540 cm2 g-1 to 392-430 m2 g-1 and pore volume from 0.27 to 0.21-0.23 cm3 g-1 for CoCl2 concentration smaller than 0.28 mol dm-3 in silica gel. Adsorbed water desorbed from the gels absorbing 1917-2555 J g-1 energy as determined by differential scanning calorimetry. The CoCl2-containing gels were successfully used in dynamic column experiments, with linear relation between velocities of inlet air and movement of blue to pink boundary. The colour change also makes the detection of the defects in column filling which causes air channellingArticle Citation - WoS: 13Citation - Scopus: 15A Study of Adsorption of Water Vapour on Wool Under Static and Dynamic Conditions(Springer Verlag, 1998) Ülkü, Semra; Balköse, Devrim; Çağa, Tayfun; Özkan, Fehime; Ulutan, SevgiAdsorption of water vapour on wool provides not only textile comfort, but also convenience in transportation due to increase in its bulk density. The adsorption and desorption isotherms of water vapour for wool were determined by both volumetric technique using a Coulter Omnisorp 100CX instrument and gravimetric method employing a Cahn 2000 electronic microbalance. Adsorption isotherm fitting to B.E.T. model and hysteresis on desorption was observed. The average effective diffusion coefficient of water in wool was found to be 8.4 × 10-14 m2 s-1 at 25°C from gravimetric data. The effects of packing height and air velocity on the breakthrough curves were also investigated in the wool packed columns. For pseudo first order model, k values changing between 0.33 × 10-6 -69 × 10-6 s-1 was obtained for 2.2-6.4 cm s-1 air velocity and 0.05-0.20 m packing height ranges.Article Citation - WoS: 19Flexible Poly(vinyl Chloride)-Zeolite Composites for Dye Adsorption From Aqueous Solutions(Taylor and Francis Ltd., 1996) Balköse, Devrim; Ulutan, Sevgi; Çakıcıoğlu Özkan, Seher Fehime; Ülkü, Semra; Köktürk, UğurFlexible poly(vinyl chloride) (PVC) composites having natural zeolite clinoptillolite were prepared by plastisol-plastigel technology. Adsoption of methylene blue on each raw material and on composites was studied both from an equilibrium and a rate approach. It was observed that the adsorption capacity of zeolite decreased when it was embedded in composites. The equilibrium uptake of methylene blue increased with an increasing zeolite fraction in composites. Methylene blue was adsorbed from a 0.02 g·cm-3 aqueous solution slowly, but was nearly adsorbed completely with a composite having a 0.3 volume fraction of zeolite. The effective diffusion coefficient of methylene blue in composites was of the order of 10-13 m2·s-1 and decreased with increasing filler fraction.