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Archived Theses
Preparation and characterization of carboxymethylcellulose based hydrogels
Carboxymethylcelusose (CMC) based hydrogels were synthesized by crosslinking methot in presence of poly(vinylalcohol) (PVA) and fumaric acid (FA) used as a crosslinker. NaCMC and PVA cross-linked with different concentrations of FA. Hydrogels were characterized with different methods (FTIR, TGA, XRD and SEM) of analysis. The water absorbencies of these hydrogels in different pH solutions were investigated. As the FA concentration was increased, equilibrium swelling capacity reduced due to increasing crosslinking between CMC and PVA. Also pH sensitivity and reversibilty of hydrogels were investigated. The results indicated that the hydogels in the base medium had higher swelling behavior than the acidic medium. More over the hydrogels had pH reversibilty behavior which swelled at pH=8 and shrinked at pH=2.6. The FTIR results indicated the cross-linking between carboxyl group of FA with hydroxyl group of PVA and NaCMC through ester formation. The thermal behavior of the hydrogels was examined by TGA/DTG. The crosslinking improved the thermal stability of the hydrogels. Furthermore the SEM analysis showed that a highly porous structure was observed for 10FA and 15FA hydrogels while for 20FA and 25FA samples firstly high fibrous structure, then dispersion was observed.
Preparation and characterization of crosslinked chitosan based hydrogels
An interpenetration network (IPN) ion-imprinting membrane was synthesized using silver ions as template for adsorption and removal of silver ions from aqueous solutions. The membrane was obtained via cross linking of chitosan (CS), polyvinyl alcohol (PVA), and blend chitosan/polyvinyl alcohol using glutaraldehyde (GA) as cross linker. Non-ion imprinted membrane was also synthesized. Chitosan and polyvinyl alcohol are not very compatible in the chitosan/ polyvinyl alcohol blended hydrogel membrane and the thermostability of the membranes is enhanced by glutaraldehyde as crosslink agent. Later synthesis, the membranes were immersed in 1 M sodium hydroxide, followed by repeatability washing with deionized water to eliminate any unreacted glutaraldehyde. Quality analysis was applied on the samples by using Tollen reagent for the determination of the unreacted glutaraldehyde. The characterization with different methods (FTIR, TGA, XRD, and SEM) for non-imprinted and silver ion imprinted membrane were examined. FT-IR analysis implies that the coordinating atoms may be nitrogen atom of amino in chitosan and oxygen atom of hydroxide in polyvinyl alcohol. Morphology and properties of silver ion-imprinted membranes were studied compared with non-imprinted and chitosan. The silver-imprinted membranes can be regenerated by using ethylenediaminetetraacetic acid and thiourea in hydrochloric acid. The amounts of silver-ions were determined by the atomic absorption spectroscopic analysis. As a result, it was found that thiourea in hydrochloric acid solution had higher removal capacity for silver (I) ions when compared with ethylenediaminetetraacetic acid.
Genel kimyada atom ve kuantum sayıları konusunda işbirlikli öğrenmenin öğrencilerin akademik başarılarına etkisi
Bu araştırmada, işbirlikli öğrenme yöntemlerinden jigsaw tekniği uygulamasının Genel Kimya dersi alan öğrencilerin ?Atom ve Kuantum Sayıları? konusundaki akademik başarılarına etkisi ve öğrenme sürecine yönelik öğrenci görüşlerinin neler olduğunun ortaya çıkarılması amaçlanmıştır.Araştırmanın örneklem grubuna 2010-2011 öğretim yılında Dokuz Eylül Üniversitesi, Buca Eğitim Fakültesi, Ortaöğretim Fen ve Matematik Alanlar Eğitimi bölümünde Genel Kimya dersi alan öğrencilerden oluşan 2 şube seçilmiştir. Bu şubelerden biri İşbirlikli öğrenme jigsaw tekniğinin uygulandığı deney grubu (n=24), diğeri ise geleneksel öğretmen merkezli öğretme yaklaşımının uygulandığı kontrol grubu (n=30) olarak rastgele atanmıştır. Araştırmaya Genel Kimya I dersini ilk kez alan toplam 54 öğrenci katılmıştır. Çalışma grubuna alınan öğrencilerde ilgili bölümlerinin 1. sınıf öğrencileri ve Genel kimya dersini ilk kez alıyor olması özelikleri aranmıştır.Atom ve Kuantum Sayıları konusunda deneysel uygulama sürecinde deney grubuna işbirlikli öğrenme yöntemlerinden Jigsaw tekniği uygulanırken, kontrol grubuna sadece geleneksel öğretim programı uygulanmıştır. Her iki gruba da deneysel uygulama öncesinde Hazır bulunuşluk testi, sonrasında Atom ve kuantum sayıları başarı testi uygulanmıştır. SPSS 15.0 paket programı kullanılarak yapılandeney ve kontrol gruplarının test ölçümlerinin karşılaştırılmasında bağımsız (ilişkisiz) örneklemler t-testi kullanılmıştır. Ardından yarı yapılandırılmış görüşme ile her iki gruptan öğrenciler seçilerek öğrenme süreci hakkındaki görüşleri alınmıştır.Araştırma sonunda, işbirlikli öğrenme ve geleneksel öğretmen merkezli öğretme yaklaşımının uygulandığı öğrenciler arasında akademik başarı düzeyi deney grubu öğrencileri lehine anlamlı bir farklılık gösterdiği bulunmuştur.Uygulanan öğretim yöntemine ilişkin öğrenci görüşlerinin alınması amacıyla; tabakalandırılmış örnekleme yöntemi kullanılarak deney grubundan 9 ve kontrol grubundan 9 öğrenci seçilmiş olup, öğrencilerle gerçekleştirilen yarı yapılandırılmış görüşme sonucunda, öğrencilerin, işbirlikli öğrenme ile bilgi paylaşımı sayesinde konuya daha hakim oldukları yönünde görüşleri ortaya konulmuştur.Anahtar Kelimeler: Kimya öğretimi, Atom ve kuantum sayıları, İşbirlikli öğrenme, Jigsaw tekniği, Akademik başarı.
Investigation of the utilization of some chromoionophores in micelle and ionic liquid containing media for ion sensing purposes
In the first part of this work, we have employed tree ionic liquids (1-butyl-3- methylimidazolium tetrafluoroborate,1-ethyl-3-methylimidazolium tetrafluoroborate 1-butyl-3- methylimidazolium thiocyanate) and two micelles (sodium dodecyl sulfate and Triton X-100) as new additives for the determination of Mn(II) with Eosin Y in aqueous solutions by spectrofluorimetric method. In the second part, photophysical constants of three ionic liquids, 1-Butyl-3- methylimidazolium thiocyanate, 1-butyl-3-methylimidazoliumtetrafluoroborate,1-ethyl-3-methylimidazoliumtetrafluoroborate were investigated in aqueous media by UV-visible absorption, emission and excitation spectra. The effect of metal cations (Ca(II), Cu(I), Hg(I), As(V), Mo(II), Li(I), Pb(II), Al(III), Cr(III), Na(I), Mg(II), Zn(II), Cd(II), Fe(III), Co(II) and Ni(II)) to the absorption and fluorescence characteristics of the ionic liquids were investigated and the acid base response of the ionic liquids were also evaluated. It has been observed that all the applied ionic liquids exhibited intense and broad emission bands from 350-600 nm. In the absorption spectra of 1-Butyl-3- methylimidazolium thiocyanate a new absorption maxima was observed by the addition of Fe(II) and Fe(III) ions, which is due to the complex formation of iron ions with SCN- group of the ionic liquid.
Investigation of the utilization of some fluorescent organic dyes in modified polymer or sol-gel matrices as optical sensor agents
In the first part of this work, three different ionic liquids, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium thiocyanate and 1-butyl-3-methylimidazolium hexafluorophosphate were employed for the modification of acid- catalyzed tetraethyl orthosilicate (TEOS) based sol-gel matrix. Photophysical characteristics and emission based response of tris (bipyridine) ruthenium (II) dye to gaseous oxygen was investigated in these ionic liquid containing sol?gel matrix by spectrofluorimetric method. Effects of the ionic liquid type, ionic liquid concentration, dye concentration and some sol gel parameters such as acid catalyze concentration; pH, gelation time, TEOS/water molar ratios and drying temperature to the oxygen sensitivity were evaluated.In the second part, the photo physical characterization of synthesized carbazole bearing oxazolones (4-[4-(9H-carbazol-9-yl)benzylidene]-2-(4-nitrophenyl)-1,3-oxazol-5(4H)-one (3), 4-[(9-methyl-9H-carbazol-3-yl)methylene]-2-(4-nitrophenyl)-1,3-oxazol-5(4H)-one (5a) and 4-[(9-hexyl-9H-carbazol-3-yl)methylene]-2-(4-nitrophenyl)-1,3-oxazol-5(4H)-one (5b) were investigated in polymer matrix of polyvinylchloride (PVC) by using absorption and emission spectrometry. The response of the dye doped PVC films were also evaluated in terms of the effect of pH and sensitivity to some metal cations and anions. The immobilized dye, 3 was found to exhibit a selective response for Zn (II) ions in direction of decrease in fluorescence intensity. Besides the selectivity of the dye to Zn (II) ions, high quantum yield value, the response in nanomolar concentrations level and high linear working range makes the dye promising for optical zinc ion sensor designs.
Antifouling performances of some sco-friendly biocides
Artificial surfaces exposed to seawater are covered by marine fouling organisms. This process is known as ?Biofouling?. When artificial surfaces are considered as ships? hull, the biofouling processes result in undesirable consequences such as increased fuel consumption, CO2 emission, friction and decreased maneuverability and speed. Many attempts have so far been done to prevent biofouling process occurred on ships? hull. These processes are called as ?Antifouling?. There are a lot of different strategies and also paint formulations for ships? hull. However, very limited solutions, strategies and also commercial products have been available for marine propellers. Self-polishing percentages of an eco-friendly commercial product, PROP PROTECTOR (lanolin based material), developed for preventing biofouling processes on propellers? surfaces were investigated dependent on temperature, rotary rate, and fibre reinforcement in the present thesis. According to results, fibre reinforcement remarkably increased the self-polishing resistance of the lanolin based material. Field test results carried out in marine eco-system also confirmed the laboratory experiments. In conclusion, the quality of the commercial product, PROP PROTECTOR, can be developed by adding special fibres and fibre reinforced lanolin based material which might be used in the warm waters.
Süt ve balda sülfonamidlerin kromatografik tayini
The sulfonamides are collected in animal tissues and organs and then they accumulate in human kidney and hepatic by following the chain of consumption. For these reasons, determination of sulfonamides becomes essential because of inhibiting folic acid synthesis and causing permanent damage.In this study, preconcentration process was performed for food products such as milk and honey with a surfactant Triton X-114 and high pressure liquid chromatography diode array detector (HPLC-DAD) was used to determine sulfadiazine (SDA), sulphamethoxazole (SMZ). Cloud point extraction (CPE) which is simple, fast, new and economic and uses surfactants fundamentally as an alternative instead of organic solvents, concerns green chemistry concept was performed for the extraction of sulfonamides. Quantitative analysis of extracts was performed in methanol/water (22:78, v/v) isocratic elution at 1.0 mL/min flow rate with 35 degrees Celsius at 270 nm after pH, salt & surfactant concentration, incubation time and temperature optimizations were completed.Detection and quantitation limits of the method were found as 5.68 and 20.09 ppb and 6.06 and 21.86 ppb for SDA and SMZ, respectively, the linear range of quantitation for analytes was approximately 0.025 - 2.000 ppm, the percentages of average recovery as 65.2% and 99.4% and the relative standard deviation percentage as 0.51% and 2.17% were found for SDA and SMZ, respectively.The results of the amount of sulfonamides in two kinds of milk and ten kinds of honey were determined as in the range of 0.062 - 0.104 ppm and 0.017 - 0.643 ppm (SDA), 0.018 - 0.038 ppm and 0.006 - 0.162 ppm (SMZ), respectively.
Reversible immobilization of catalase by metal chelate affinity interaction on a new generation matrix
p(AAm-AGE) cryogel was prepared by radical polymerization of acylamide and allyl glycidyl ether. Cibacron Blue F3GA is covalently attached on p(AAm-AGE) cryogel, via the reaction between the chloride groups of the reactive dyes and the epoxide groups of the AGE. Cibacron Blue F3GA attached p(AAm-AGE) cryogel was chelated with Fe(III) ions. p(AAm-AGE)-CB-Fe(III) cryogel was characterized by FTIR, SEM and swelling degree analysis. The IMAC cryogel carrying 25.8µmol Fe(III) ions was used in adsorption studies under different conditions (i.e., pH, protein initial concentration, flow rate, temperature and ionic strength). Maximum adsorption capacities were found to be 75.7 mg/g for p(AAm-AGE)-CB-Fe(III) cryogel and 60.6 mg/g for p(AAm-AGE)-CB cryogel, respectively, and the adsorbed amounts per unit mass of cryogel reached to a plateau value at about 1.5mg/mL at pH 6.0. Michealis-Menten constant and Vmax values were significantly affected by adsorption of catalase onto the p(AAm-AGE)-CB-Fe(III) cyyogel. The Km values were found to be 0.73 g/L for the free catalase and 0.18 g/L for the immobilized catalase. The Vmax value of free catalase (2.0x103 U/mg enzyme) was found to be lower than that of the immobilized catalase (2.5x103 U/mg enzyme). Activity of immobilized catalase was determined higher in a wider temperature range than the free enzyme. It was also observed that enzyme could be repeatedly adsorbed and desorbed on the p(AAm-AGE)-CB-Fe(III) cryogel.
Katışıklı zeytin yağlarında katıştırılan yağın cinsi ve oranının FTIR spektroskopisi ve kemometrik yöntemlerle belirlenmesi
Bu çalışmada, Aydın'daki yağ üretim fabrikalarından temin edilen saf zeytinyağı numuneleri ile yine benzer üretim yerlerinden alınan pamuk yağı, marketlerden temin edilen saf mısırözü ve ayçiçeği yağı numunelerinin FTIR Infrared spektrofotometresinde spektrumları alınarak aradaki farklar incelenmiştir.Daha sonra, zeytinyağı ile yukarıda bahsi geçen bitkisel yağların belirli oranlarda karışımları hazırlanmış ve her bir numune için 10 adet olmak üzere toplam 190 adet spektrum, SİMCA-P istatistik programı kullanılarak kemometrik yöntemlerden başlıca bileşen analizi modellemesi ile sınıflandırılmıştır. Saf yağlara ait IR spektrumlardaki küçük farklara dikkat çekilmiş ve IR spektrum ve kemometri ile saf yağların birbirinden kolayca ayrılabildiği gösterilmiştir. Ayrıca, başlıca bileşen analizinin zeytinyağının, diğer üç yağdan biri ve hacimce en az % 10 olmak koşulu ile, katışıklı olup olmadığını belirlenmede etkin bir yöntem olduğu sergilenmiştir.Saf yağlar ve zeytinyağına diğer yağların değişik hacim oranlarında katılmasıyla hazırlanan karışımlarda öz ağırlık, kırılma indisi, sabunlaşma sayısı, iyot sayısı ve peroksit sayısı tayinleri yapılmıştır. Katılan yağın miktarı ve ölçülen büyüklük arasında çizilen grafiklerde bu ilişkinin doğrusal olduğu gösterilmiştir. Grafiklerdeki doğruların eğimlerinin yön ve büyüklüğünden yararlanarak katışıklı zeytinyağlarında katılan yağı cinsinin belirlenmesi için gerekli koşullar tartışılmıştır
Sodyum metakrilat içeren çapraz bağlı akrilamid esaslı kopolimerlerin hazırlanışı, karakterizasyonu ve biyopotansiyel kullanım kapasitelerinin araştırılması
Bu çalışmada, akrilamid monomeri ile birlikte yardımcı monomer; sodyum metakrilat kullanılarak, kimyasal çapraz bağlı kopolimerlerin sentezi, karakterizasyonu ve sentezlenen polimerlerin yüzeye soğurum özelliklerinin araştırılması amaçlanmıştır. Kimyasal çapraz bağlı akrilamid/sodyum metakrilat polimerleri, 1,4-bütandiol dimetakrilat, etilen glikol dimetakrilat ve trimetilolpropan triakrilat çapraz bağlayıcıları kullanılarak sulu çözeltide serbest radikalik polimerleşme tepkimesi ile hazırlanmıştır. Tepkimede başlatıcı olarak amonyum persülfat, hızlandırıcı olarak N,N,N',N'-tetrametiletilendiamin kullanılmıştır.Kimyasal çapraz bağlı polimerlerin yapısal karakterizasyonu Fourier Transform İnfrared Spektroskopisi (FT-IR) analizi ile yapılmıştır. Çapraz bağlı akrilamid/sodyum metakrilat kopolimerlerinin biyopotansiyel kullanım alanlarını örneklemek amacı ile ürenin sulu çözeltilerinde ve suda şişme karakterizasyonu için 25oC'da dinamik şişme testleri uygulanmıştır. Şişme kinetiği ve difüzyon mekanizması ile ilgili parametreler şişme çalışmaları kullanılarak hesaplanmıştır.Kimyasal çapraz bağlı akrilamid/sodyum metakrilat kopolimerlerinin yüzeye soğurum özelliklerinin araştırılmak için Safranin T gibi bir boyarmadde seçilmiştir. Kimyasal çapraz bağlı akrilamid/sodyum metakrilat kopolimerleri, 25oC'ta Safranin T'nin sulu çözeltileri ile dengeye gelinceye dek etkileştirilerek soğurum özellikleri araştırılmıştır.