Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
Browse
70 results
Search Results
Research Project Süperkritik Akışkan Ekstraksiyonu ile Bor Minerallerinden Borik Asit Üretimi(2014) Gönen, Mehmet; Akçil, Ata Utku; Pamukoğlu, Muhammet Yunus; Balköse, DevrimSüpekritik etanol ile tinkal mineralinden %32 verimle borik asit ayrıştırılmış; süperkritik karbondioksit ile su ortamında kolemanit mineralinden %98 verimle borik asit ekstraklanmıştır. Proje doğal kaynaklarımızdan temel bor kimyasalı, borik asit, üretiminde atmosferde sera gazı etkisi oluşturan CO2?nin kullanılması yönüyle önemlidir. Baca gazları içindeki CO2 kolemanit reaksiyonu sonucunda kararlı bir bileşik olan kalsite (CaCO3) dönüşmektedir. Bu proses kolemanit mineralinden borik asit üretiminin yanında CO2 tutulumu da sağladığından dolayı sürdürülebilir ve çevreci bir prosestir. SüperPro Designer programı ile hem geleneksel (kolemanit-H2SO4) hemde geliştirilen (kolemanit-süperkritik CO2) prosesler için proses dizayn yapılmış ve prosesler teknik ve ekonomik açıdan karşılaştırılmıştır.Book Part Water Sorption of Polyvinyl Chloride-Luffa Cylindrica Composites(Taylor & Francis, 2014) Demir, Hasan; Balköse, DevrimNatural Luffa Cylindrica fibers were modified with 0.1M sodium hydroxide (NaOH) for removing lignin and hemicellulose. Natural and modified Luffa fibers were characterized by using IR spectroscopy. Composites were produced with PVC plastisol and natural Luffa fiber. Natural Luffa fiber is a highly hydrophilic substance. This feature increased the water sorption capacity of the composites. Flexible PVC-luffa cylindrica composites had higher liquid water sorption capacity (0.3-0.6%) compared to that of flexible PVC (0.1%). There was no volume change of composites due to liquid water sorption.Book Part Citation - Scopus: 2Influence of Filler Surface Modification on the Properties of Pp Composites(Wiley, 2015) Balköse, DevrimThis chapter reviews the fillers have been grouped as silica, glass, silicates, magnesium hydroxide and eggshell, cellulose and carbon, and their surface modification techniques. It explains the effects of the surface modification of fillers on the properties of composite materials having polypropylene as the matrix. The surface modification of fillers affects the properties of the polypropylene matrix composites in different aspects depending on the types of the filler and the modifications. The polypropylene phase was also functionalized by treating PP with MA or ammines. The properties most affected are the tensile strength, Young modulus, and elongation at break of the composites. If crosslinking occurs between the filler and functionalized PP, the tensile strength increases and elongation at break decreases owing to decrease in mobility. PP crystallite formation at the interface also increases the adhesion between filler and matrix. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA. All rights reserved.Book Part High-Performance Materials and Engineered Chemistry(CRC Press, 2018) Türk, Merve; Gümüş, Barış; Ustun, Fatma; Balköse, DevrimNano-sized nickel borate hydrate were precipitated from equimolar mixtures of dilute nickel nitrate and borax solutions at 25°C. Produced nickel borate samples were characterized by TGA, DSC, FTIR spectroscopy, X-ray diffraction, SEM, Elemental Analysis (EDX), Titration (nickel determination by EDTA, B<inf>2</inf>O<inf>3</inf> determination by NaOH), Particle Size Distribution, and Dehydration. The particles with 55 nm, 80 nm and 70 nm sizes were obtained for the cases without template, with span 60 and PEG 4000 in the reaction mixture respectively. The empirical formula of the vacuum dried precipitates were NiO.1.3B<inf>2</inf>O<inf>3</inf>.5.6 H<inf>2</inf>O, NiO.1.2B<inf>2</inf>O<inf>3</inf>.5.6 H<inf>2</inf>O and NiO.1.0B<inf>2</inf>O<inf>3</inf>.5.4 H<inf>2</inf>O for the cases without template, with span 60 and PEG 4000. The density of the nickel borate hydrates was around 2 g/ml and they had a color described by 157, 199 and 158 in RGB color scale. The nickel borate hydrates were amorphous in structure and no sharp peaks related to a crystal structure was present in their x-ray diffraction diagram. The effect of presence of span 60 and PEG 4000 were not significant on the particle size and chemical composition of the nanoparticles. © 2019 Elsevier B.V., All rights reserved.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: 6Citation - Scopus: 9Preparation and Characterization of Flexible Polyvinylchloride-Copper Composite Films(Smithers Rapra Technology, 2013) Kurt, Emrah; Özçelik, Cenk Yağız; Yetgin, Senem; Özmıhçı Ömürlü, Filiz; Balköse, DevrimFlexible PVC films are statically charged due to their low electrical conductivity. This creates fire threat during its handling. Conductive materials are added to films to prevent this. In the present study it was aimed to prepare PVC- copper composite films by sol gel technique and characterize the prepared films. It was aimed to increase the electrical conductivity of the films by adding copper powder. However, the copper particles settled down to bottom instead of forming a conductive network that covers the whole cross section. Thus at the film crosssection a plastic upper phase and a copper rich lower phase were present. The film did not conduct electricity due to this uneven distribution. The minimum volumetric and surface resistivities of the films were at the order of 109 ohm-cm and 1010 ohm square respectively.Article Citation - WoS: 2Citation - Scopus: 10Water and Water Vapor Sorption Studies in Poly(propylene)-Zeolite Composites(John Wiley and Sons Inc., 2003) Pehlivan, Hilal; Özmıhçı, Filiz; Tıhmınlıoğlu, Funda; Balköse, Devrim; Ülkü, SemraWater and water vapor sorption to porous poly(propylene)zeolite composites prepared by hot pressing have been studied as a function of zeolite loading. This work presents the first report on the effect of the zeolite as a filler on the water sorption properties of PP composites. Water swelling experiments were conducted at 25°C using pure PP and PP-zeolite film samples having different zeolite loadings (6-40 wt%). Since PP is a hydrophobic polymer, it does not sorp any water, but the composites having 10, 20, 30, and 40% zeolite sorbed 0.63, 1.00, 1.72 and 3.74 wt% water, respectively. The zeolite itself at the same conditions sorbed 24.5 wt% water. As the filler loading in the composites increased, equilibrium uptake values increased too. On the other hand, water vapor sorption and kinetics has been studied using a Cahn 2000 gravimetric sorption system. Within in the range 0.35-0.95%, water vapor was adsorbed by the composites containing 10-40 wt% zeolite. Experimental effective water vapor diffusivities of the composite films were about one order of magnitude higher than the experimental water diffusion coefficient in composites. The transport of water in composites was slower than that in the liquid water due to the longer diffusion pathway and adsorption on the surface of the composites. Although the liquid water may fill all the voids in the composite, water vapor is adsorbed on the surface of the zeolite only.Article Citation - Scopus: 5Nano Zinc Borate as a Lubricant Additive(Turkish Chemical Society, 2018) Savrık, Sevdiye Atakul; Üstün, Fatma; Alp, Burcu; Balköse, DevrimLubricants consist of base oils and chemical additives such as dispersants, surfactants, oxidation inhibitors, and antiwear agents. Organic and inorganic boron-based additives increase wear resistance and decreases friction. Hexagonal boron nitride and metal borates are used for this purpose. Zinc borate is a synthetic hydrated metal borate. The production techniques of zinc borate generally include the reaction between zinc source materials (zinc oxide, zinc salts, zinc hydroxide) and the boron source materials (boric acid and borax). The nano zinc borate particles were prepared from zinc nitrate and borax in the present study by using low initial zinc and borate concentrations and low temperature to prevent particle growth. The templates span 60 and PEG 4000 were used to control the particle size. The particles were separated from mother liquor by centrifugation, washed with ethanol, dried and ground and used as additive to base oil. The particles have H2O and B(3)-O vibrations in their FTIR spectra. The empirical formula of the nanoparticles was approximately 3ZnO.2B2O3.4H2O from EDX and TGA analysis. X-ray diffraction diagram indicated the particles were in amorphous state. When the nanoparticles were added to light neutral oil the wear scar diameter and friction coefficient was lowered 50% and 20% respectively.Article Citation - WoS: 4Citation - Scopus: 5Dynamic Heat of Adsorption of Water Vapour on Zeolitic Tuff and Zeolite 4a by Flow Microcalorimetry(Scibulcom Ltd., 2006) Ülkü, Semra; Balköse, Devrim; Alp, BurcuIn this study a practical method for measurement of heat of adsorption of water vapour on adsorbents was developed to evaluate the feasibility of substitution of a zeolitic tuff with zeolite 4A in air drying and heat pumps. The change of heat of adsorption with inlet humidity of the air passing through the calorimeter was investigated. Samples were characterised by X-ray diffraction and thermal gravimetric analysis techniques. Specific heats of the zeolitic tuff and zeolite 4A were measured as 1.01 and 1.42 J/g K, respectively. Adsorption isotherms fitted to the Langmuir model with regression coefficient 0.93 and 0.94 with monolayer capacities, Xm 9.68% and 26.35% H 2O for the zeolitic tuff and zeolite 4A, respectively. The energy storage intensity was measured in the range 48-97 J/g and 464-201 J/g for the tuff and zeolite 4A, respectively. Heat of adsorption of zeolite decreased with surface coverage and it was in the range 1750-2835 and 1104-2640 J/g H 2O for the zeolitic tuff and zeolite 4A, respectively.Article Citation - WoS: 2Citation - Scopus: 2A Study of Chemical and Physical Changes During Biaxially Oriented Polypropylene Film Production(Walter de Gruyter GmbH, 2003) Ülkü, Semra; Balköse, Devrim; Arkış, Esen; Sipahioğlu, MuzafferPolypropylene films obtained during the biaxial orientation process were characterized by energy dispersive X-ray analysis (EDX), scanning electron microscopy. X-ray diffraction, differential scanning calorimetry, infrared spectroscopy. Inorganic particles with Al, Si, Na, Mg, Ti, K,O elements were present in biaxially oriented films. Polypropylene had molecules with both isotactic configuration and it was crystallized only in isotactic α phase. The films drawn in one and two directions had unit cells with b axis parallel to surface of the films. The antioxidants present in the films were consumed during processing, preventing polypropylene oxidation in air at high processing temperatures. One surface of the films contained less polypropylene and had functional groups rich in oxygen such as C=O and COO.