Publications

  • Mf Can, L Avdan, A.Bedeloglu
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    ABSTRACT: In this study, poly(vinyl alcohol) (PVA) nanocomposite fiber mats with sepiolite were prepared via electrospinning technique. The measurements of fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), contact angle, scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used for the characterization. The effect of polymer/sepiolite ratio and heat treatment on the properties of samples was investigated. The heat treatment which decreased the solubility of nanofibers and the addition of sepiolite resulted in a decrease in nanofiber diameter, contact angle with water, and water drop spreading rate on the material, and also resulted in an increase in water drop spreading rate inside the material. POLYM. COMPOS., 2014. © 2014 Society of Plastics Engineers
    Polymer Composites 12/2014; · 1.46 Impact Factor
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    Selçuk Koltka, Muhammed Fatih Can, Eyup Sabah
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    ABSTRACT: The lower quality and fine (< 425 µm) sepiolites are not available for usage as cat-litter due to their non-granular structure. It is only possible to economically evaluate this type of sepiolite when ingredient impurities are cleaned off the body and enhance the rheological properties. Especially the sepiolites those display rheological properties may find usage as final ingredient in drilling mud, paint, adhesives, asphalt, filler material, animal food, catalyst support and carrier, cosmetics, fertilizer suspensions, oil refining, pharmacy and ceramics industry. Within the scope of this study two types of fine size (< 425 µm) sepiolites (Brown and White) probability to be enhanced in MGS (Multi Gravity Separator) with gravitational separation method, as a result of this it is aimed to obtain higher viscosity producing sepiolite concentrates. For the enrichment experiments performed with MGS; structural parameters(drum rotation rate, drum inclination, vibration amplitude and wash water rate) effect on separation has been investigated, further for optimization of enrichment parameters, the products viscosity values have been considered as success measure. Experiments have been designated with Taguchi experiment design method and the results have been evaluated with SPSS 17.0 software to define the optimum parameters. Run of mine Brown sepiolite viscosity has increased from 740 cP to 1057.7 cP with an enrichment efficiency of 69.6%, where White sepiolite viscosity has increased from 69 cP to 112.2 cP with an enrichment efficiency of 56.2%.
    15. Ulusal Kil Sempozyumu, Niğde-Turkey; 09/2012
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    ABSTRACT: Controlling the wettability of nano textured surface structures is essential for understanding of its role particularly in biomedical applications. The main objective of this study is to explore the wetting mechanism of a water drop on a nano textured Si surface. Si nano-columns with 4-, 3- and 2-fold in-plane symmetries were grown on p-type (100) Si wafer by oblique angle deposition (OAD). The surface morphology was characterized by scanning electron microscopy (SEM). The contact angle technique was used to reveal the wetting characteristics of these textured surfaces. Experimental results were compared with the theoretical contact angle calculations derived from the Young, Wenzel and Cassie-Baxter equations in order to identify the conditions for the minimum free energy of the drop. Water droplets on all plenary symmetries water droplets showed good agreement with the Cassie-Baxter model of Sunny side up. These findings were used to simulate the extent of the hydrophilicity on the fabricated textures by taking the contact angle hysteresis (CAH) into account.
    Materialwissenschaft und Werkstofftechnik 05/2012; 43(5). · 0.51 Impact Factor
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    Muhammed Fatih Can, Eyup Sabah
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    ABSTRACT: Recovery of fine coals from coal preparation tailings and recycle of processing water are of both economic and environmental incentives, not only preserving natural resources but also reducing environmental consequences of discharging large volume of tailings. Recent developments in the use of various gravity equipments in fine-coal beneficiation have been discussed and their relative merits have been compared. In this study, the application of multiple linear regressions and Taguchi experimental design method for modeling and optimizing of some operations variables of Multi-Gravity Separator (MGS) and Falcon concentrator for lignite coal cleaning was discussed. The variables considered in this study include the pulp solid ratio, drum speed, tilt angle, shaking amplitude, wash water rate, feed rate for MGS, and the gravity force, solids rate, flow rate, water pressure for Falcon concentrator. The positive and negative effects of variables and the interaction between variables ash content and recovery of clean coal were determined. The predicted values were found to be in good agreement with experimental values (R2 values of 0.807 and 0.944 for ash content and combustible recovery of clean coal, respectively) for MGS. However, the match of predicted values with the actual data points indicates a poor fit (R2 value of 0.577 and 0.399 for ash content and combustible recovery values, respectively) of the equation for Falcon concentrator.
    01/2012; 14(28):26-32.
  • Materialwissenschaft und Werkstofftechnik 01/2012; 43(5):366-372. · 0.51 Impact Factor
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    ABSTRACT: We prepared biocomposite gel dispersions involving sodium alginate (Na-Alg) and calcium bentonite (Ca-B) with various solid concentrations and characterized their rheological, electrokinetic, and morphological properties. The flow properties, such as the apparent and plastic viscosities, shear stress, and yield value point, changed with increasing clay dosage. The viscosities of the homogeneous dispersions were represented by the Herschel–Bulkley model. The ζ-potential results were examined in the light of different characterization methods (X-ray diffraction, Fourier transform infrared spectroscopy, and atomic force microscopy) to understand the interactions between the Na and Ca ions of the alginate biopolymer and bentonite clay. A plausible structural model for the alginate–bentonite composite gel, known as the egg-box model, is proposed. The presence of Ca ions in the Ca-B partially crosslinked Na-Alg may be regarded as an excellent example of a self-assembling process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.
    Journal of Applied Polymer Science 10/2011; 122(1). · 1.40 Impact Factor
  • Selçuk Özgen, Muhammed Fatih Can, Eyup Sabah
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    ABSTRACT: Lignite coal is the primary domestic source of energy in Turkey, for this reason effective exploitation of the reserves of Turkey is very crucial. In Turkey the fine tailings of lignite coal processing plants are sent in most cases to the tailing ponds without any treatment. However, recovery of fine coals from coal preparation tailings and recycle of processing water are of both economic and environmental incentives, not only preserving natural resources but also reducing environmental consequences of discharging large volume of tailings. Recent developments in the use of various gravity equipments in fine-coal beneficiation have been discussed and their relative merits have been compared. In this study, the possibility of beneficiation of lignite tailings included quartz, kaolinite, siderite, mica/illite, dolomite, feldspar compounds in the Tunçbilek/Kütahya region was investigated by Multi Gravity Separator (MGS) and Falcon Concentrator and these two methods compared. The entire exercise revealed that the MGS could produce a clean coal with an ash content of 22.83%, 5696 kCal/kg calorific value and a recovery of 49.32% and that the Falcon could produce a clean coal with an ash content of 40.26%, 4224 kCal/kg calorific value and a recovery of 64.53% from a feed coal having an ash content of 66.21% and 1835 kCal/kg calorific value.
    International Pittsburgh Coal Conference, İatanbul-Turkey; 10/2010
  • Selçuk Özgen, Muhammed Fatih Can, Eyup Sabah
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    ABSTRACT: Lignite coal is the primary domestic source of energy in Turkey, for this reason effective exploitation of the reserves of Turkey is very crucial. In Turkey the fine tailings of lignite coal processing plants are sent in most cases to the tailing ponds without any treatment. However, recovery of fine coals from coal preparation tailings and recycle of processing water are of both economic and environmental incentives, not only preserving natural resources but also reducing environmental consequences of discharging large volume of tailings. Recent developments in the use of various gravity equipments in fine-coal beneficiation have been discussed and their relative merits have been compared. In this study, the possibility of beneficiation of lignite tailings included quartz, kaolinite, siderite, mica/illite, dolomite, feldspar compounds in the Tunçbilek/Kütahya region was investigated by Multi Gravity Separator (MGS) and Falcon Concentrator and these two methods compared. The entire exercise revealed that the MGS could produce a clean coal with an ash content of 22.83%, 5696 kCal/kg calorific value and a recovery of 49.32% and that the Falcon could produce a clean coal with an ash content of 40.26%, 4224 kCal/kg calorific value and a recovery of 64.53% from a feed coal having an ash content of 66.21% and 1835 kCal/kg calorific value.
    International Pittsburgh Coal Conference, İstanbul-Turkey; 10/2010
  • Muhammed Fatih Can, Selçuk Özgen, Eyup Sabah
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    ABSTRACT: The multi-gravity separator (MGS) is a novel piece of equipment for the separation of fine and ultra-fine minerals. This study was conducted to evaluate the effects of different process variables on the performance of the Multi Gravity Separator (MGS) for beneficiation of Turkish lignite and hard coal fine tailings to recover ultra-fine coal. The main minerals of Tunçbilek lignite tailings are kaolinite, illite and mica. The dominant minerals of Zonguldak hard coal tailings are chlorite, quartz, mica, calcite, pyrite, and amorphous materials. Various operating and design conditions of MGS such as drum speed, tilt angle, shaking amplitude, wash water rate, feed rate and pulp solid ratio were investigated. A hydrocyclone was used for pre-enrichment with the MGS. Operation parameters of the hydrocyclone, namely feed solids, inlet pressure, vortex finder and apex diameters were investigated. The results showed that clean coal was obtainable with 22.83% ash, 5.696 kCal/kg calorific value and recovery of 49.32% from lignite has 66.21% ash and 1.835 kCal/kg calorific value, with 6.98% ash, 7.214 kCal/kg calorific value and recovery of 85.61% from a hard coal has 28.41% ash and 5863 kCal/kg calorific value by this two-stage concentration process.
    International Pittsburgh Coal Conference; 10/2010
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    ABSTRACT: Sepiolite is a natural clay mineral characterized by a nanofiber structure, unique crystal morphology and composition, and high surface area. It is capable of producing stable suspensions of high viscosity at lower solid concentrations. Dispersion of sepiolite fibers in water can increase the inner and outer surface areas of fibers in the form of a network which enables adsorption of water molecules within the inter particles resulting in a significant increase on the viscosity of the suspension. The viscosity of 3% (w/w) sepiolite suspension prepared at 21,000 rpm remarkably increased with increasing the stirring time from 1 to 3 min. Sepiolite particles are expected to disperse in water to nanosizes. Towards this aim, an Atomic Force Microscopy (AFM) study was undertaken to determine the dimensions of the fibers against the stirring time. The sepiolite suspensions stirred for 1 min showed that the fibers remained in the form of bundles. An increase in the stirring time to 3 min caused the fibers to break into pieces on all dimensions but less effective on the length. However, in the case of 5 min of stirring time, those broken fiber pieces could not organize themselves in a randomly establishing network and thus led to a significant viscosity reduction. The AFM study revealed that the average fiber dimensions at the highest viscosity were determined as 249 × 1127 × 29 nm (width × length × height). The size distribution of fibers is elaborated in order to define an optimum strategy for fiber disintegration.
    Applied Clay Science 02/2010; · 2.70 Impact Factor
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    ABSTRACT: Bu çalışmada flint taşı artığından yüksek saflıkta kuvars elde edebilmek için cevher içerisindeki renk verici mineraller ve feldspatlar flotasyon yöntemi ile uzaklaştırılmıştır. Mineralojik incelemelerde artıkta bulunan kuvarsın serbestleşme tane boyutu -63 μm olarak belirlenmiş, yeterli serbestleşme tane boyutuna ulaşabilmek için artık bu tane boyuta ufalanmış ve bunun için gerekli olan öğütme parametreleri optimize edilmiştir. Flotasyon yöntemiyle artıktan yüksek verimle kuvars kazanımı için ortam pH’sı, toplayıcı, bastırıcı ve köpürtücü miktarları ile devir hızı, köpük derinliği ve katı konsantrasyonu gibi önemli flotasyon değişkenlerinin optimizasyonu yapılmıştır. SiO2 tenörü %94,1 olan flint taşı artığından katyonik toplayıcı kullanılarak feldspat-kuvars ters flotasyonu ile pH 2,5’de %97,7 SiO2 tenörlü konsantre, %96,49 SiO2 kazanma verimiyle elde edilmiştir.
    Journal of Science, Afyon Kocatepe University. 01/2009; 9(2):61-75.
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    ABSTRACT: Effects of different acids (HCl, H2SO4 and citric acid) on rheological properties of brown sepiolite from the Eskisehir region of Turkey have been determined. The optimum apparent viscosity value was obtained at the natural pH of the suspension. Below the natural pH, partial collapse of the structure due to the release of Mg ions causes a significant decrease in viscosity values. However, below pH 1, there is a substantial increase in viscosity values owing to gel formation. On the other hand, above the natural pH of suspension, increased amounts of OH ions lead to a decrease in viscosity values and inhibit gel formation. The reversible nature of sepiolite was tested by changing the pH of acid and alkaline treated sepiolite suspensions back to its natural pH by washing with water and acid, respectively. In summary, from a practical point of view, there is no favorable effect of acid treatment of sepiolite on its rheological properties. On the contrary, reducing the pH to natural pH after grinding in a basic environment led to an improvement in rheological properties.
    Applied Clay Science 01/2009; 42:422-426. · 2.70 Impact Factor
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    ABSTRACT: In this work, chemically modified sodium montmorillonite and epoxy monomer were used to prepare nanocomposites in two consecutive stages. In the first stage, dodecylamine, octadecylamine, hexadecylamine, and hexadecyltrimethyl ammonium bromide were used to prepare various organophilic clays. In the second stage, the bisphenol-A based epoxy monomer and predetermined amounts of organoclay were mixed together and then cured by an aliphatic polyamine for 20 min under microwave at 400 W. Furthermore, -ω diacrylate poly(dimethylsiloxane) was added to the mixture before the curing process to modify the toughness of the samples. The mixture was poured into the poly(tetrafluoroethylene) mold; the epoxy resin/curing agent ratio was maintained as 2/1. The clear films formed after microwave irradiation were removed from the mold, cooled, and then stored in a cool and dry medium until characterization. The samples were analyzed by wide angle X-ray diffraction, differential scanning calorimetry, and mechanical tests. Surfaces of the cold fractured samples were also observed under the scanning electron microscope. The results revealed that microwave curing of the samples of 5% organoclay and 5% siloxane showed improvement in mechanical properties. POLYM. ENG. SCI. 46:1104–1110, 2006. © 2006 Society of Plastics Engineers
    Polymer Engineering and Science 07/2006; 46(8):1104 - 1110. · 1.24 Impact Factor
  • 12. Ulusal Kil Sempozyumu; 09/2005
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    ABSTRACT: Application of the thin-layer wicking (TLW) technique on powdered minerals is useful for characterizing their surfaces. Albite (Na-feldspar) and orthoclase (K-feldspar) are feldspar minerals which are frequently found in the same matrix. Despite similarities in their physicochemical properties, separation of these minerals from each other by flotation is generally possible in the presence of monovalent salts such as NaCl. Both albite and orthoclase exhibit the same microflotation properties and rather close electrokinetic profiles in the absence of salt. In this study, contact angles of albite and orthoclase determined by the TLW technique yielded close values in the absence and presence of amine collector. While the calculated surface energies and their components determined using contact angle data reveal that the energy terms remain farther apart in the absence of the collector, the differences narrow down at collector concentrations where full flotation recoveries are obtained. However, the effect of addition of NaCl on contact angles and surface free energy components at constant amine concentration indicates that albite is significantly affected by salt addition, whereas orthoclase remains marginally affected. This interesting finding is explained on the basis of ion-exchange properties, the stability of the interface, flotation data, and zeta potential data in the presence of NaCl.
    Journal of Colloid and Interface Science 06/2005; 285(1):192-200. · 3.55 Impact Factor
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    ABSTRACT: Modification of zeolite (clinoptilolite) surface with a quaternary amine, hexadecyl trimethyl ammonium bromide (HTAB), to improve the removal efficiency of reactive azo dyes in a zeolite fixed bed was investigated. A series of adsorption tests were conducted to find out the uptake of three types of reactive dyes, i.e. CI Reactive Black 5, Red 239 and Yellow 176. Each run consisted of modifying zeolite with HTAB in the column followed by removal of color from the modified zeolite bed. The breakthrough curves for modification process were constructed under different conditions by plotting the normalized effluent concentration (C/C(0)) versus time or bed volumes (BV). Optimization studies show that 3g/l of HTAB dosage at a flowrate of 0.025l/min showed the best performance. Examination of the dye removal under the optimum modification conditions reveals that the black dye gives the highest breakthrough point among the three dyes tested. This is ascribed to the hydrophobic/hydrophilic match of the zeolite surface with the dye molecule, which depends upon the way zeolite is modified with HTAB. Calculations of the HTAB coverage on zeolite surface indicate that a bilayer formation is the most viable packing that enables maximum removal of the dye.
    Water Research 01/2005; 39(2-3):487-93. · 5.32 Impact Factor

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