Theses supervised by Prof. Dr. Kadriye Ertekin
10 theses · Dokuz Eylül University
New fiber optic competible chromoionophore/matrix combinations for hco3- analysis in real groundwater samples
Dissolved and gaseous carbon dioxide is an important parameter in water samples, industrial, biochemical and medical applications. Mostly, correct analysis of gaseous and dissolved carbon dioxide is difficult due to the matrix effects. Here we intended to investigate new approaches for optical analysis of dissolved carbon dioxide in groundwater samples. Our investigations focused on newly synthesized choromoionphores or their combination with new matrix materials. We performed their spectral chacterization in transperent polymers and tested their compatibility to solid state optics.In this work, the ion pair form of pH indicator dye, 8-hydroxypyrene-1,3,6-trisulfonicacidtrisodiumsalt was used for the gaseous CO2 detection. Poly (methyl methacrylate) and ethyl cellulose were used as polymeric materials. Sensing slides were fabricated by electrospinning technique. In this sensor design, the response time, reversibility, linear concentration range and repeatability characteristics also have been studied. Similarly newly synthesized dyes N'-[(E)-(9-methyl-9H-carbazol-3-yl) methylidene] pyridine-4-carbohydrazide and N'-{(1E, 2E)-3-[4-(dimethylamino) phenyl] prop-2-en-1-ylidene} pyridine-4-carbohydrazide were characterized by spectroscopic ways in thin film or nanofiber form in the ethyl cellulose and poly (methyl methacrylate) polymers. Acidity constant and quantum yield calculations of the employed dyes were performed in the conventional solvents and/or in the solid matrices. Their fluorescence based response to dissolved CO2 were examined both in thin film and nanofiber form. Their cross sensitivities to anions, metal cations were tested.The indicator dyes namely N'-[(E)-(2-hydroxyphenyl) methylidene] pyridine-4-carbohydrazide (MY2), N'-[(E)-(3-hydroxyphenyl) methylidene] pyridine-4-carbohydrazide (MY4), N'-[(E)-(4-nitrophenyl) methylidene] pyridine-4-carbohydrazide (MY5), were spectroscopically chacterized and offered for emission based analysis of bicarbonate anion. Acidity constant values of three indicator dyes were calculated and cross sensitivities to other cations and anions were also tested and evaluated.Bicarbonate analysis in groundwater samples was performed by spectrophotometric and volumetric (indicator and potentiometric) methods. Obtained results were compared with proposed method.
Design of optical chemical nanosensors for Determination of some selected cations and anions in Aqueous samples and evaluation of interference effects
In this thesis, we designed original optical chemical nanosensors exploiting electrospun nanofibrous materials for optical sensing of silver (I), mercury (II), iron (III), hydroxyl, calcium (II) and copper (II) ions at sub-nanomolar levels in aqueous samples.Poly(methyl methacrylate) and ethyl cellulose were used as polymeric materials together with appropriate fluoroionophores and other additives. Cation and /or anion sensing nanomaterials were fabricated by electrospinning that the most convenient way to make a nano-scale continuous polymer uses a high static voltage to draw the fiber from a liquid polymer.Sensors were based on the change in the fluorescence signal intensity of all employed ionophore. The offered nanosensors allow determination of ions in a large linear working range. The preliminary results of Stern?Volmer analysis show that the sensitivities of electrospun nanofibrous membranes to detect ions are 10-100-fold higher than those of the thin film based sensors. The extraordinary sensitivities can be attributed to the high surface area of the nanofibrous membrane structures that provided faster sensor dynamics in applications. In all of the sensor designs, sensor performance characteristics such as the response time, long-short term stabilities, reversibility, limit of detection, linear concentration range, repeatability and interference effects also have been studied.Last of all, we have successfully combined the nanoscale electrospun fiber materials with optical sensing technology exploiting apropriate fluoroionophores for subnanomolar sensing of ions without interference effects.
Development of nano material based sensors for determination of some-cation/anion in groundwater and complementary usage of ion chromatography
In this thesis, novel materials using electrospun nano-scale polymeric fibers has been proposed as a promising material for sensing trace amounts of cations in water and groundwater systems. The offered sensors operate by detecting fluorescence intensity changes of fluoroionophore embedded in polymer matrices. The spectral characterization and sensor properties of seven different ionophores were described. Some of the exploited dyes were newly synthesized and used for the first time for sensing purposes. Highly sensitive emission based nano-scale sensors for Copper (II), Mercury (II), Iron (III) and Tin (II) were fabricated. We performed spectral characterizations of the ionophores in conventional solvents and in solid matrices. Then, we investigated the selectivity and following the sensor performances of the ionophores into detail in terms of sensitivity, selectivity, working range, short-term stability and response time. We checked accuracies of the offered sensors exploiting recovery tests and used them in real groundwater samples. A great effort has also been made for development of a sensor to detect the conventional anions throughout the studies. We observed a significant response only for bicarbonate and hydroxyl ions with ODC-3 and ODC-5 dyes. The observed response was not a selective response for bicarbonate but rather, a response to pH in the alkaline range of the pH scale. Throughout the thesis, for each fluoroionophore, we compared results of thin films and electrospun nanofibers and revealed the advantages of the nano-scale materials over existing thin films. Here, we performed coupling of electrospun nanomaterials with fluorescence based measurement techniques without scattering and other side effects. By this way, we attained detection limits extending to sub-picomolar levels. Further efforts will focus on exploring new sensing materials and polymer compositions, controlling the nanoscale size of the electrospun membranes, and optimizing the sensitivities for the detection of a variety of analyses. Keywords: Sensor, nanosensor, optical chemical sensor, fluorescence, Hg (II),
İşyeri ortamlarında hava kalitesinin ölçümünde kullanılan temel örnekleme ve analiz metodları ve ilgili standartlar
Kimyasal maddelere maruz kalmada en muhtemel yol inhalasyon (soluma) olduğundan solunan havanın her türlü kimyasal, toz ve gazlardan arınmış olması gerekir. Çalışma ortamlarında bulunan hava kirleticilerin başında uçucu organik ve inorganik bileşikler ile belli boyutun altında solunabilir toz ve partiküller gelmektedir. Sıcaklık, nem, rüzgar gibi meteorolojik parametreler ile havalandırma da kirlilik üzerine etkili olmaktadır. Yukarıda söz edilen hava kirleticiler izin verilen düzeylerin üzerinde olduğunda kronik hastalıklardan başlayıp kitlesel ölümlere kadar giden sağlık zararlarına neden olurlar. Bu nedenle çalışma ortamlarındaki hava kalitesinin sürekli kontrolü ve izlenmesi son derece önemlidir. Hava kirliliğinin analizi konusunda kimyager, çevre mühendisi gibi yetişmiş insan kaynaklarımız olmakla beraber konunun iş sağlığı güvenliği ayağında boşluklar bulunmaktadır. Bu konuda hem ulusal ve uluslar arası standartları kapsayan ayrıntılı dokümanlara hem de çok yönlü yetişmiş insan kaynaklarına gereksinimimiz vardır. Bu tez çalışmasında özellikle iş yeri ortamında hava kalitesinin kontrolüne yönelik olarak yapılacak test ve analizler ele alınmış, ilgili standartlar da dikkate alınarak ayrıntılı olarak incelenmiştir. İş yeri ortamlarında insan sağlığı için uygun hava kalitesinin sağlanabilmesinde ve sürdürülebilmesinde kontrol ve denetimlerin rolü çok büyüktür. Bu prosedürler doğru örnek almak ve alınan örnekleri ulusal ve uluslararası standartlara uygun şekilde ve tayin limitleri dikkate alınarak analizleme basamaklarından oluşur. Hazırlanmış olan bu dökümanın konu ile ilgili tüm paydaşlar için bilgilendirici bir kaynak olma potansiyeli bulunmaktadır.
Development of nano-material based optical chemical sensors indicating oxygen levels in petrochemistry related workplaces
In workplaces, especially in refineries, volatile petroleum solvents are usually in the form of mixtures of alkanes, cyclic alkanes, alkenes and the aromatics. Such atmospheres which are deficient in oxygen may not provide adequate sensory warning of danger. Therefore correct and continuous monitoring of oxygen levels in such environments is quite important. On the other hand, ruthenium (II) derivatives are known as oxygen sensitive dyes and have intensively been used in the design of optical chemical sensors. Most of the ruthenium dyes suffer from leaching from host matrices due to the water solubilities. In order to provide the best host/dye compatibility we used the amphiphilic ruthenium derivatives in silicon based matrices. In this work, emission-based oxygen sensing properties of highly luminescent ruthenium (II) derivatives were tested in the presence and absence of some volatile organics. Newly synthesized two orange-red emitting alkyl branched ruthenium complexes were used along with silver nanoparticles (AgNPs) in two different silicon based matrices for oxygen sensing purposes. The sensing materials were fabricated in form of thin films and electrospun nanofibers. Ionic liquid and perfluorinated compounds were exploited as additives to enhance the response to oxygen. Oxygen induced spectral changes at 630 nm were followed for both gas phase and dissolved oxygen as the analytical signal. The oxygen sensitivities of the probes were also tested by lifetime based and kinetic mode measurements. Utilization of the amphiphilic Ru dyes in silicon along with AgNPs in the form of electrospun fibers resulted in many advantages such as enhanced long term stability, increased surface area, sensitivity and improvement in all sensor dynamics. Sensing characteristics of the offered design were tested and calibrated in the presence of vapors of benzene, toluene, ethylbenzene, hexane and xylene, which simulate refinery related work places.
Bazı fosfor/organik boya kombinasyonlarının polimerik matrikslerde optik özelliklerinin ve stabilitelerinin araştırılması
Phosphors are commercially important chemicals because they are used as raw materials in mobile phones, personal computers, LCD screens, light emitting diode (LED) and white light emitting diode (WLED) technologies. In this thesis, commercially available phosphors of Lu3Al5O12:Ce3+ (LuAG:Ce3+), (Y,Gd)3Al5O12:Ce3+ (YAG:Ce3+) and CaAlSiN3:Eu2+ (CASN:Eu2+) were investigated to enhance their spectral properties rather than the known approaches. The green, yellow and red phosphors were chosen to represent a large spectral range available in the screen technologies as well as LED applications. All phosphors were prepared in thin film form in a polymethyl methacrylate (PMMA) matrix. The light harvesting materials of nano-scale ZnO and CuO, have been used to improve the spectral properties of the LuAG:Ce3+ and YAG:Ce3+. In this process, fluorescence, phosphorescence, and excited state lifetimes were monitored and promising experimental results were obtained. Mechanisms indicating possible energy transfers between the species have been revealed. In the second part of the thesis, the energy transfer between phosphors and Tris (1,10-phenanthroline) ruthenium (II) hexafluorophosphate dye (Ru(phen)3PF6) has been investigated. The binary blends of the LuAG:Ce3+, YAG:Ce3+ and CASN:Eu2+ with the Ru(phen)3PF6 exhibited promising results in the presence of the ionic liquid (IL). Long-term photo stabilities of the composites supported with the IL were investigated during 8 months. No significant effect of the IL on photo-stability levels was detected.
Optoelekrtonik uygulamalara yönelik nano malzeme destekli florofor, fosfor veya fosfor karışımlarının polimerik matriksler içerisinde incelenmesi
In this thesis we investigated the interactions between the commercially available LED phosphorus and nano-scale materials or dyes in terms of their emission abilities in polymers. In the first part of the thesis, photoluminescence of the Eu2+ doped Ca-α-Sialon (Ca-α-SiAlON:Eu2+), Ce3+ doped lutetium aluminum garnet (LuAG:Ce3+) and their binary blends with the quinine sulphate (QS) were investigated by steady-state and decay time measurements. The Ca-α-SiAlON:Eu2+ exhibited 44% increase in the intensity when blended with the QS. Similarly, the binary blend of QS-LuAG:Ce3+ exhibited 98% enhancement in the intensity. Excited state lifetimes of the phosphors were also studied in nanosecond and microsecond time scales, respectively. Spectral data presented some evidence for the donor-acceptor relationship of the QS/ Ca-α-SiAlON:Eu2+ and QS/LuAG:Ce3+ counterparts where the QS was the donor. The offered phosphor blends, exhibited enhancement in the optical brightness without any spectral shift. In the second part of the thesis, CO2 sensitive HPTS dye was used along with the bioactive glasses and ionic liquid. The bioactive glasses equipped with the rare earths of Er3+, Tb3+ and Er3+and Tb3+, were chosen due to their porous structure, optical transparency and intrinsic fluorescence. After spectral characterization steps we exposed the composites towards varying concentrations of the CO2 and recorded the intensity based response both in steady-state and kinetic mode. We also determined the decay times in the absence and presence of the CO2. We obtained promising results from the studies performed by using the bio-compatible bioactive glasses in terms of enhanced optical brightness and CO2 sensitivity.
İzmir Çiğli atıksu arıtma tesisi için kimyasal hijyen planı oluşturulması
Atıksu arıtma tesisleri, tehlikeli kimyasalların yoğun kullanıldığı iş yerlerinden biridir. Bu işletmelerde kullanılan kimyasal maddelerin tehlikelerinin belirlenmesi ve bu tehlikelerle proaktif olarak mücadele edilmesi çalışanların iş sağlığı ve güvenliğinin sağlanması açısından oldukça önemlidir. Bu sebeple, bu çalışmada öncelikle İzmir Çiğli Atıksu Arıtma Tesisinde gerçekleştirilen faaliyetlerde kullanılmakta olan tehlikeli kimyasalların tespit edilmesi amaçlanmıştır. Daha sonra bu tehlikelerden doğacak risklerin belirlenmesi ve çalışanlara yönelik oluşabilecek zararların proaktif olarak bertaraf edilmesi için kimyasal hijyen planı hazırlanmıştır.
Dijital radyografi sisteminin tasarımı, geliştirilmesi ve üretimi
The development of scintillation materials are important because of the ever-increasing need for materials in high-energy physics and digital radiography. The present composition of the scintillators consists of organic or inorganic materials, each of which is suitable for different applications. Inorganic crystal scintillators are widely used because of their superior energy solubility and stiffness for high energy radiation. In the scope of the thesis, inorganic Gd2O2SO4 phosphorescent nanoparticles which are doped with pure and rare earth elements (Dy3+, Ce3+, Eu3+, Ho3+, Pr3+, Tb3+) are optimized according to the density of the dopants. In line with this optimization, scintillator materials were produced by the sol-gel method and characterized. The characterization process was carried out separately in three different production stages, namely solution, gel, and final product. In this process, the pH and turbidity values of the solutions were determined. Slightly acidic (pH: 6.1) and fully dissolved solutions were obtained. FTIR analysis was performed to determine organic bonds to the sol-gel material, and DTA-TG thermal analyzes were performed to determine exothermic-endothermic reactions. The heat treatment temperature required to find the correct phase was determined at this stage. The final product was then obtained and characterization was completed using FTIR, XRD, XPS, SEM and PL devices, respectively. When the characterizations are evaluated in detail, it is seen that the produced Gd2O2SO4: RE3+ nanoparticles are successfully produced in the desired phase structure and nanostructure. In addition, the specific emission spectra and decay times of each of the nanoparticles activated with different rare earth elements have been determined. This clearly shows that the produced scintillators can also be used in different detectors for the intended purpose in digital imaging.
Investigation of optical properties and sensing potentials of some organic dyes in polymeric matrices
In this thesis, spectral properties and selective sub-nano molar response towards the ionic silver of the newly synthesized Y10 dye has been investigated. The excitation and emission spectra of the dye has been recorded in the solutions of tetrahydrofurane (THF), diclorometane (DCM) and ethyl alcohol (EtOH). Herein we investigated spectral properties of the fluorescent Y10 dye in plasticized polyvinyl chloride (PVC) polymethyl methacrylate (PMMA) and in ethyl cellulose (EC). In addition to the plasticizer the lipophilic anionic additive and ionic liquid were also utilized and effect of these additives on the spectral response has been evaluated. The Y10 dye exhibited better spectral response in EC. In later studies the EC has been used as matrix material. Response towards the ionic silver has been investigated in phosphate buffered solutions at pH 7.06 for the IL-Free and IL-Doped composites. The best limit of detection (LOD) value has been reported as 1.1x10-15 M silver. The decay time measurements were used to explain the mechanism behind the response. While the IL-Doped films exhibiting a linear response for the concentration range of 10-4-10-12 M, the electrospun fibers made up of the same material exhibited the linear response for the concentration range of 10-8-10-12 M. The EC doped Y10 dye exhibit as selective spectral response towards silver in presence of excess amounts of mercury(II), aluminum(III), calcium, copper(II), iron(III), potassium, manganese, magnesium, and lead at neutral pH. When the dye doped into EC along with appropriate additives can be used as an emission based sensor for silver for a large linear concentration range of 10-12 to 10-4 M.