Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Research Project Tuzla (Çanakkale) jeotermalinin bölgedeki akifere toprağa ve suya etkilerinin araştırılması(TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2005) Baba, Alper; Özcan, Hasan; Yılmaz, Selahattin; Kavdır, Yasemin; Deniz, Ozan; Yiğini, Yusuf; Yılmaz, Sevinç; Baba, BarışTürkiye'nin sıcaklık bakımından üçüncü önemli sahası durumunda olan Tuzla jeotermal sahasındaki akışkanın yöredeki toprağa ve suya olan etkileri irdelenmiştir. Soğuk ve sıcak su kaynaklarının özelliklerini ve birbirleri ile olan ilişkilerini belirlemek amacıyla Ağustos 2003, alık 2003, Mart 2004 ve Haziran 2004 tarihlerinde su numuneleri alınmıştır. Bu su -numunelerinden major anyon, katyon, ağır metal ve çevresel izotop (18O, 2H, 3H) analizleri yapılmıştır. Ayrıca 0-30; 30-60; 60-90; 90-120 cm derinliklerinde ise toprak numunelerinde ise bazı fizikokimyasal özellikler, ağır metal ve radyoaktivite çalışmaları gerçekleştirilmiştir. Sıcak sular, denizel kökenli evaporıtik yataklardan çözünerek gelen sular olup, tatlı sular ile karışım göstermektedir. Sahadaki tüm sular meteorik kökenli olup, tatlı yeraltı suları ile connate (hapis) tuzlu suyun karışımından ibarettir. Sahasının güneydoğusundan gelen EC'si düşük (600-800 micromho/cm) yeraltı sularının jeotermal sular etkisi ile EC'sinin (1400-3200 micromho/cm) yükseldiği görülmektedir. Nitekim CaHCCVlü sular fasiyesinde yer alan yeraltı suları sıcaksularm etkisi ise CaCVlı sulara geçiş göstermektedir. Proje sahasındaki jeotermal suların Tuzla tatlı yeraltı suyu akiferine olan olumsuz etkileri iki şekilde olmaktadır: a) Jeotermal suların yeraltı sularına mevsimlik etkisi, ki buna dolaylı etki denebilir: kurak dönemde yüzeyde biriken tuz ve ağır metal bileşimlerinin, kışın yağışlar vasıtası ile yeraltına süzülmesi, b) Sahada çıkan yüksek basınca sahip jeotermal suların yukarıya doğru dikey çatlak, kırık veya faylar vasıtası ile yükselimi, yani genel anlamda yeraltı suyuna etkisi. Jeotermal suların yukarıda belirtilen her iki etkisinden ötürü yeraltı suyunun duraylı izotop değerleri beklenilenden daha pozitif değerlerdedir. Genel olarak, inceleme alanındaki sıcak suların da yukarıya doğru çıkarken soğuk yeraltı suyu akiferine karışımından ötürü 518O ve 6D değerlerinde bir azalma da söz konusu olmuştur.Research Project Bazı ilaç aktif maddelerin farmasötik preparatlarda ve insan serumu gibi biyolojik sıvılarda eletktroanalitik metotlar (Voltametrik ve polarografik teknikler ile tayini(TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2005) Özkan, Sibel; Yılmaz, Selahattin; Uslu, Bengi; Dilgin, Yusuf; Yağmur, Sultan; Süren, Esin; Akgün, NurBu çalışmada, elektroaktif grup içeren bazı ilaçaktif maddelerin camsı karbon disk ve karbon pasta elektrotlarda farklı tampon ortamında voltametrik davranışları araştırıldı. Pik potansiyeline ve pik akımına, konsantrasyonun, pH 'nın tarama hızının etkisi incelendi. Alt tayin sınırı (LOD) ve Kantitatif tayin sınırı (|LOQ) belirlendi. Çalışılan bazı bileşikler için yükseltgenme veya indirgenme mekanizmaları da önerildi. Bu teknikler ile maksimum pik akımının gözlendiği ortamda ilaçaktif maddelerin farmasötik preparatlarda ve serum gibi biyolojik sıvılarda tayini yapıldı. Ayrıca kesinlik ve geri kazanım çalışmaları yapıldı. Bazı etken maddelerin önerilen elektroanalitik teknikler ile yapılan ilaçlardaki miktarı , UV-Spektrofotometrişininki ile karşılaştırıldı. Böylelikle önerilen elektroanalitik metodların doğruluğu ve üstünlüğü araştırıldı.Article Citation - WoS: 11Citation - Scopus: 13Effect of Cnt Incorporation on Pan/Ppy Nanofibers Synthesized by Electrospinning Method(TÜBİTAK, 2020) İnce Yardımcı, Atike; Tanoğlu, Metin; Yılmaz, Selahattin; Selamet, YusufIn this study, carbon nanotubes (CNTs) added polyacrylonitrile/polypyrrole (PAN/PPy) electrospun nanofibers were produced. Average diameters of the nanofibers were measured as 268 and 153 nm for 10 and 25 wt% of PPy contents, respectively. A relatively higher strain to failure values (23.3%) were observed for the low PPy content. When as-grown CNTs (1 and 4 wt%) were added into the PAN/PPy blends, disordered nanofibers were observed to form within the microstructure. To improve the interfacial properties of CNTs/PAN/PPy composites, CNTs were functionalized with H2SO4/HNO3/HCl solution. The functionalized CNTs were well dispersed within the nanofibers and aligned along the direction of nanofibers. Therefore, beads formation on nanofibers decreased. The impedance of the nanofibers was found to decrease with the PPy content and CNT addition. These nanofibers had a great potential to be used as an electrochemical actuator or a tissue engineering scaffold.Article Citation - WoS: 2Catalytic Activity of Heteropolytungstic Acid Encapsulated Into Mesoporous Material Structure(Walter de Gruyter GmbH, 2007) Gündüz, Gönül; Dimitrova, Rayna P.; Yılmaz, SelahattinThe paper presents a spectroscopic and catalytic study of encapsulated Keggin type heteropoly acid (12-tungstophosphoric acid, HPW) in the mesopores of MCM-41 molecular sieves. Nitrogen physisorption, FTIR, SEM, XRD and catalytic methods have been used to characterize and compare the properties of the samples. Methanol conversion, alpha-pinene isomerization and ethyl acetate oxidation have been applied as model reactions for the evaluation of acid site activity. The combined physicochemical and catalytic investigations clearly show that the introduction of 12-tungstophosphoric acid into MCM-41 causes significant changes in the properties of the sample.Article Citation - WoS: 17Citation - Scopus: 19Heavy Naphtha Upgrading by Catalytic Reforming Over Novel Bi-Functional Zeolite Catalyst(Springer, 2018) Ahmedzeki, Nada S.; Al-Tabbakh, Ban A.; Antwan, Maher B.; Yılmaz, SelahattinNaphtha catalytic reforming process using bimetallic platinum and titanium loaded on nano synthesized HY zeolite was investigated for the product octane number enhancement. The activity of five samples of the prepared catalyst with different bimetallic loading of 0.13, 0.25 wt% Pt and 0.75, 1, 2.2 wt% Ti were investigated for Iraqi heavy naphtha catalytic reforming at the temperature range of 490, 500 and 510 degrees C and pressure of 10 bar in a packed bed pilot plant reactor. The best result of the research octane number was 84 for reformate product using the sample of 0.13% Pt-0.75% Ti%/HY zeolite at temperature 510 degrees C and 10 bar achieving 47% increase. All samples of the prepared catalyst showed a good stability during the operation at severe conditions and the maximum carbon content was about 9% due to the deposition of coke precursor on the catalyst surface. The reformate yield was investigated for all catalyst samples under 10 and 20 bars and the same range of temperature and ranged from 89 to 94%. These results are encouraging for future possible replacement of the conventional catalyst by the local synthetic zeolite. Octane number was correlated on the basis of constituent's boiling points. The maximum absolute error between the experimental and predicted octane number was about 3 and 5% using 10 and 20 bar respectively.Article Effective Synthesis of Cetyl Palmitate Over Co-Precipitated Wo3-Zro2 Catalysts(Springer Verlag, 2018) Mutlu, Vahide N.; Yılmaz, SelahattinThis study is focused on the development of solid acid catalysts for the synthesis of long chain fatty acids. A series of WO3-ZrO2 catalysts were prepared by co-precipitation method and tested in the synthesis of cetyl palmitate. The effect of WO3 loading (10, 15, and 20 wt% WO3) and calcination temperature (700 and 800 degrees C) on the catalyst properties and activity was investigated. XRD and Raman analysis confirmed that WO3 loading stabilized the tetragonal zirconia phase. Higher calcination temperature enhanced the acidities of the catalysts. WO3-ZrO2 catalysts were found to be very efficient for the synthesis of cetyl palmitate with high selectivity. These catalysts were tested for different reaction temperatures (135 and 162 degrees C), feed composition and catalyst amounts. The highest cetyl palmitate yield (98.4%) was obtained over the catalyst calcined at 800 degrees C with 15 wt% WO3, which had the highest total acidity. The catalysts preserved their activities up to three reuse.Article Citation - WoS: 18Citation - Scopus: 17Cnt Incorporated Polyacrilonitrile/Polypyrrole Nanofibers as Keratinocytes Scaffold(Trans Tech Publications, 2019) İnce Yardımcı, Atike; Aypek, Hande; Öztürk, Özgür; Yılmaz, Selahattin; Özçivici, Engin; Meşe, Gülistan; Selamet, YusufPolypyrrole (PPy) is an attractive scaffold material for tissue engineering with its non-toxic and electrically conductive properties. There has not been enough information about PPy usage in skin tissue engineering. The aim of this study is to investigate biocompatibility of polyacrilonitrile (PAN)/PPy nanofibrous scaffold for human keratinocytes. PAN/PPy bicomponent nanofibers were prepared by electrospinning, in various PPy concentrations and with carbon nanotube (CNT) incorporation. The average diameter of electrospun nanofibers decreased with increasing PPy concentration. Further, agglomerated CNTs caused beads and disordered parts on the surface of nanofibers. Biocompatibility of these PAN/PPy and PAN/PPy/CNT scaffolds were analyzed in vitro. Both scaffolds provided adhesion and proliferation of keratinocytes. Nanofiber diameter did not significantly influence the morphology of cells. However, with increasing number of cells, cells stayed among nanofibers and this affected their shape and size. In this study, we demonstrated that PAN/PPy and PAN/PPy/CNT scaffolds enabled the growth of keratinocytes, showing their biocompatibility.Article Citation - WoS: 13Citation - Scopus: 13Fe Containing Zsm-5 Zeolite as Catalyst for Wet Peroxide Oxidation of Orange Ii(Walter de Gruyter GmbH, 2011) Bolova, Emre; Gündüz, Gönül; Dükkancı, Meral; Yılmaz, Selahattin; Yaman, Yadigar CeydaThis study presents the catalytic performances of iron containing ZSM-5 zeolites, prepared by ion exchange or hydrothermal synthesis, in catalytic Fenton-like oxidation of Orange II in aqueous solution. The catalyst, ZSM-5 zeolite with Si/Al ratio of 42 loaded with iron by ion exchange, showed the highest activity. The decolorization of 99.7 percent, degradation of 87.0 percent and COD removal of 81.2 percent were achieved over this catalyst at an initial pH of 3.5. Incorporation of iron into ZSM-5 structure increased its catalytic activity. The hydrothermally prepared FeZSM-5 catalyst was more stable against leaching at low pH value due to the iron being in the framework.Article Citation - WoS: 30Citation - Scopus: 31Esterification of Cetyl Alcohol With Palmitic Acid Over Wo3/Zr-sba-15 and Zr-Sba Catalysts(Elsevier Ltd., 2016) Mutlu, Nahide Nuran; Yılmaz, SelahattinTungsten loaded and Zr incorporated SBA-15 catalysts (WO3/Zr-SBA-15 and Zr-SBA-15) were developed for esterification of cetyl alcohol and palmitic acid. The influence of the Zr content, tungsten loading amount, calcination temperature, feed composition and catalyst amount has been studied. Higher tungsten loading decreased the acidity due to formation of WO3 crystals whereas calcination temperature enhanced the acidity by favoring the dispersion of WOx species. Activities of the catalyst changed depending on their amount of Brønsted sites and total number of acid sites. Zr-SBA-15 catalyst which had the highest amount of Brønsted acid sites gave maximum cetyl palmitate yield (63.1%). This catalyst retained its activity up to 3 reuse cycles without significant loss of activity.Article Citation - WoS: 41Citation - Scopus: 42Fructose Dehydration To 5-Hydroxymethylfurfural Over Sulfated Tio2-Sio2, Ti-Sba Zro2, Sio2, and Activated Carbon Catalysts(American Chemical Society, 2015) Kılınç, Emre; Yılmaz, SelahattinDifferent sulfated catalysts including SO4/TiO2-SiO2, SO4/Ti-SBA-15, SO4/ZrO2, SO4/AC, and SO4/SiO2 were tested in fructose dehydration to 5-hydroxymethylfurfural (HMF). Reactions were carried out in dimethyl sulfoxide (DMSO) at 110 °C. Characterization results indicated that no sulfur leaching was observed from SO4/ZrO2, SO4/TiO2-SiO2, and SO4/Ti-SBA-15 catalysts in the reaction tests. The SO4/TiO2-SiO2 catalyst had a high amount of strong acid sites and the highest amount of Bronsted sites. The highest selectivity to HMF at high conversion, that is, 89% selectivity at 77% fructose conversion was obtained over this catalyst. It preserved its activity after four times reuse.Activated carbonCarbonCatalystsDehydration
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