The need for alternative transportation fuels is rising with the rapid depletion of oil reserves and the simultaneous growth of the world&amp / #8217 / s population. Production of dimethyl ether, a non-petroleum derived attractive fuel-alternate for the future, is a challenging research area. Different routes and various solid-acid catalysts are being developed in order to achieve the most efficient way of synthesizing this potential diesel alternative fuel. The focus of heterogeneous catalysis is to convert renewable feed stocks to valuable chemicals. Nafion resin and heteropolyacid compounds are active acidic catalysts with significantly low surface areas, which act as a strong barrier limiting their catalytic activity. Synthesizing solid-acid catalysts by incorporation of nonporous active compounds into mesoporous silicate structured materials opens a door to producing valuable chemicals by heterogeneous catalysis. The objective of this work was to synthesize and characterize nafion and heteropolyacid incorporated nanocomposite catalysts and to catalyze DME synthesis by dehydration of methanol at different temperatures. The interactions of methanol and DME with these catalysts were also investigated by in situ FT-IR. Silicotungstic acid (STA)/Silica and Tungstophosphoric acid (TPA)/Silica catalysts were synthesized by following a one-pot hydrothermal route. These mesoporous catalysts had surface area values of 143-252 m2/g. The STA/SiO2 nanocomposite catalyst having a W/Si atomic ratio of 0.33 showed the highest activity, with a DME selectivity approaching to 100% and a methanol conversion of 60% at 250&deg / C at a space time of 0.27 s.g.cm-3. Effects of W/Si atomic ratio and the synthesis procedure on the performance of these novel materials were investigated. Nanocomposite Nafion/SiO2 solid-acid catalysts having high surface area values (595-792 m2/g) and narrow pore size distributions (4.3 nm) were successfully synthesized by a one-pot hydrothermal procedure. Effects of the modifications in the synthesis procedure concerning the surfactant removal, nafion loading, etc. were investigated based on the characterization results and activity tests. Nafion was observed to be uniformly distributed within these mesoporous catalysts. Nafion resin was also impregnated into aluminosilicate and &amp / #945 / -alumina, but one-pot synthesis was concluded to be better for obtaining well dispersed, nafion incorporated active catalysts. The Nafion/Silica catalyst synthesized by a nafion/silica weight ratio of 0.15 and washed with 2M sulfuric acid-ethanol solution exhibited the highest activity due to its highest Br&ouml / nsted, as well as Lewis acidity. A methanol conversion of 40% at 300&deg / C, 0.27 s.g.cm-3 and DME selectivity values approaching to 100% over 180&deg / C were very promising for the synthesis of this green fuel alternate over the new catalysts synthesized.

A proven strategy, donor-acceptor approach, to reduce the band gap of conjugated materials and possibly improve the photocurrent is to incorporate electron-rich and electron-deficient units in an alternating fashion in a polymer chain. For this purpose, a wise selection of donor and acceptor moieties in a monomer structure results in desired finishing properties of polymeric materials. In this study, fourteen novel monomers were synthesized to explore the acceptor and donor effects on the electronic and optoelectronic properties. Dibenzophenazine, dibenzopyrido]quinoxaline, tetrahydro- dibenzophenazine, thiadiazoloquinoxaline, pyrazinoquinoxaline, thienopyrazine, benzoselenadiazole, thienoselenadiazole were used as acceptor moieties, while thiophene, 3-hexylthiophene and 2,3-dihydrothienodioxine (EDOT) were used as the donor components in these donor-acceptor molecules. To synthesize desired monomers, well-known synthetic methods were performed, including bromination, nitration, reduction and condensation. Bromination was achieved by two different ways depends on the aim, NBS and Br2/HBr medium. For the nitration, HNO2 and H2SO4 were used together. Fe metal in refluxing acetic acid was used as the reducing agent in case of nitro group reductions. On the other hand, Zn metal/AcOH system was chosen for the reduction of both nitro groups and thiadiazole structure to amine, simultaneously. Finally, the Stille Coupling was used to obtain resulting acceptor-donor-acceptor monomers. These synthesized monomers were polymerized by electrochemically and investigated their properties by methods such as spectroelectrochemistry, kinetic and colorimetry studies. Spectroelectrochemistry experiments were performed in order to investigate key properties of conducting polymers such as band gap, maximum absorption wavelength, the intergap states that upon doping and evolution of polaron and bipolaron bands. Switching time and optical contrast of the polymers were evaluated via kinetic studies.

In this thesis, six different biosensors based on conducting polymers of poly 4-(2,5-di(thiophen-2-yl)-1H-pyrrole-1-l) benzenamine [poly(SNSNH2)] and poly(1- (4-nitrophenyl)-2,5-di(2-thienyl)-1H-pyrrole [poly(SNSNO2)] were prepared. Electrochemical technique was used for polymerization of conducting polymers and two different immobilization techniques / crosslinking and adsorption were used for immobilizing enzyme or microbial in the conducting polymer matrices. The proposed biosensors were characterized and optimized. Optimum pH, thickness of conducting polymer and biological material amount were determined. Linearity, repeatability and operational stability experiments were performed. Carbon nanotubes and gold nanoparticles were also added to the biosensing system to see the effects of nanoparticles. The biosensors also used for ethanol and/or glucose biosensing in commercial samples. In the first part of thesis, a biosensor was designed by immobilizing Gluconobacter oxydans in poly(SNSNH2) matrix on graphite electrode. The biosensor preparation method was a two-step procedure where the cells were immobilized by adsorption on the surface after the electropolymerization step.Use of dialysis membrane to cover the surface after immobilization conserves the bioactive surface during the operation. The preparation is simple and not time consuming. Systems proposed showed good linearity and repeatability as well as high operational stability. Glucose amount in fruit juice, ethanol amount in vodka and whisky were determined. In the second part of thesis, a second biosensor was designed with electrochemical polymerization of 1-(4-nitrophenyl)-2,5-di(2-thienyl)- 1H-pyrrole via cyclic voltammetry on graphite electrode. Afterwards, Pseudomonas fluorescens and Gluconobacter oxydans were immobilized successfully on the conducting polymer matrix separately. The proposed biosensors showed good linear range, and repeatability as well as high operational stability. In the third and fourth parts, gold nanoparticle and carbon nanotube effects were studied on poly(SNSNH2)/glucose oxidase biosensor, respectively. Covalent binding of glucose oxidase was achieved to poly(SNSNH2) by the help of glutaraldehyde on the top of graphite and carbon paste electrodes. Nanoparticle amount and optimum pH were determined for both biosensors. After analytical characterization, glucose amount in two fruit juices were determined with poly(SNSNH2)/GOx/AuNP and poly(SNSNH2)/ GOx/CNT biosensors. In the last part, biosensor was designed with immobilizing alcohol oxidase in poly(SNSNH2) matrix via crosslinking with glutaraldehyde on platinum electrode. The proposed biosensor was characterized and optimized in terms of thickness, enzyme loading, pH, AuNPs, CNTs, linear range, repeatability and operational stability.

More attention has been paid to find new type renewable energy sources because of increasing concern about the environmental problems arising from the combustion of fossil fuels as energy sources. The development of new storage materials will facilitate the use of hydrogen as a major energy carrier. Several possibilities exist for &lsquo / &lsquo / solid-state&rsquo / &rsquo / storage: the hydrogen can be trapped in metal organic frameworks, carbon nanotubes and certain alloys / or one can use materials in which hydrogen is already present in the composition (e.g., chemical hydrides). The latter option seems to be the most promising since it permits a higher mass ratio of hydrogen. Recently, ammonia-borane complex (NH3BH3, AB) has been considered as solid hydrogen storage material since it possess one of the highest hydrogen contents (19.6 wt. %) and high stability under the moderate conditions. Hydrolysis and methanolysis are the two reactions liberating hydrogen from AB. However, a catalyst is needed for hydrogen generation from methanolysis of AB. In this context, we aim to develop PVP-stabilized palladium(0) and ruthenium(0) nanoclusters as catalyst for the methanolysis of AB. The PVP-stabilized palladium(0) and ruthenium(0) nanoclusters were prepared from the in-situ reduction of palladium(II) acetylacetonate and ruthenium(III) chloride respectively in the methanolysis of AB. The prepared palladium(0) nanoclusters were isolated as solid materials by removing the volatile in vacuum and characterized by using TEM, SAED, XPS, FT-IR, XRD and UV-visible electronic absorption spectroscopy techniques while and ruthenium(0) nanoclusters were characterized by TEM, XPS, XRD, FT-IR and UV-visible electronic absorption spectroscopy techniques. The kinetics of methanolysis of AB catalyzed by palladium(0) and ruthenium(0) nanoclusters were studied depending on the catalyst concentration, substrate concentration and temperature. The activation parameters of the catalytic methanolysis reaction obtained from the evaluation of kinetic data.

Different kinds of nanoparticles are widely used in optoelectronic and photovoltaic applications to harvest light to increase efficiency of devices. ETS-10, which is a synthetic microporous material consisting of &ndash / Ti-O-Ti-O-Ti- wires that run in the crystal in a and b directions, has been of interest in such applications due to its unique properties. In the current study, the synthesis conditions of ETS-10 were investigated in order to obtain pure ETS-10 crystals with the desired morphology. For this purpose, ETS-10 crystals were synthesized using different molar compositions. The effects of several synthesis parameters on the obtained products were investigated. Furthermore, ETS-10 thin films were prepared on ITO glass substrates using secondary growth of ETS-10 for the first time. The orientation of the -Ti-O-Ti-O-Ti- wires inside ETS-10 were explored by preparing several ETS-10 films on the ITO glass substrates using secondary growth of ETS-10 multilayers with a partial a(b)-out-of-plane preferred crystal orientation. This orientation can be desirable for the advanced applications of ETS-10 films. Afterwards, silver nanoparticle modified ETS-10 crystals were prepared and characterized in detail to understand the interaction of silver nanoparticles with the synthesized ETS-10 crystals. For this purpose, ETS-10 in the as-prepared and silver nanoparticle containing forms have been characterized using, XRD, ICP-OES, SEM, HR-TEM, N2 Adsorption, XPS, and UV/VIS spectroscopy. In order to investigate the optical properties of the silver modified ETS-10, transmittance-reflectance measurements were carried out. In general, it is believed that all steps necessary for the preparation of ETS-10 films and preliminary steps for investigating ETS-10 for future photovoltaic applications were determined.

In this study, the aim was to achieve high concentration of recombinant human growth hormone (rhGH) production by recombinant Pichia pastoris by investigating the effects of various operation parameters and to determine the suitable peptide ligand sequence that shows affinity and specificity to hGH. In this context, firstly the effect of temperature and Tween-20/80 addition on production and cell growth were investigated. While at T=30 and 32&deg / C, there was no difference, at 27 and 25&deg / C cell growth slowed down and production decreased significantly. The addition of Tween-20/80 in existence of co-substrate sorbitol did not affect the bioprocess while in absence of sorbitol Tween alone did not show the same positive effect on product formation and cell growth. Thereafter at T=30&deg / C, without addition of Tween, three sets of pilot scale bioreactor experiments were performed. In the first set, the effect of methanol feeding rate on bioprocess characteristics were investigated at the specific growth rates of &mu / =0.02, 0.03 and 0.04 h-1. While the highest cell concentration was achieved at &mu / =0.04 h-1, the highest rhGH concentration was achieved at &mu / =0.03 h-1. Secondly, conducting methanol feeding at &mu / =0.03 h-1, pH=5.5 experiment was conducted. The highest cell concentration, 45 g L-1 and maximum rhGH concentration 0.25 g L-1 were achieved at t=18 h of the process. Finally, the effect of batch sorbitol feeding on bioprocess was observed by the addition of 50 g L-1 sorbitol at t=0, 14 and 31 h of the production phase. It was shown that sorbitol addition to the medium increased process duration / hence cells enter stationary phase after a longer production phase. However, the protease concentration continued increasing with respect to time and at the end of the process reached twice the concentration it was obtained with single sorbitol addition case decreasing the rhGH concentration. In selection of the peptide sequence that shows affinity towards hGH, phage display method was conducted. Additionally the sequences from literature and computational design were used as alternatives. The interaction between these peptides and hGH was investigated by isothermal titration calorimetry and surface plasmon resonance.

Novel 1,4-chiral diamine ligand possessing a trans-9,10-dihydro-9,10-ethanoanthracene backbone was synthesized. The synthetic plan involves first LiAlH4 reduction of the Diels-Alder adduct obtained by reaction of dimenthyl fumarate and anthracene, which is followed by reacting the corresponding alcohol and subsequent attachment of mesylate and triflate units to get good leaving groups which are available substances for introducing nitrogen units via SN2 type reactions. Consequently, by using dimesyl ester and ditriflate esters five catalysts 27, 29, 30, 33 and 38 were synthesized. The first four catalysts 27, 29, 30 and 33 were used in transfer hydrogenation reactions with transition metal whereas catalyst 38 used as an organocatalyst in direct aldol reaction between acetone and p-nitrobenzaldehyde.

Denim production is one of the leading sub-sectors of textile industry which basically generates highly colored indigo dyeing effluents. In the present study, ozonation was applied to the indigo-dyeing effluent(COD=820 mg/L / color=5500 Pt-Co), and to the whole effluent from a denim-producing plant before(COD=2750 mg/L / color=3950 Pt-Co) and after(COD=800 mg/L,color=3700 Pt-Co) biological treatment for degradation/detoxification purposes. Ozonation was also tried in the wastewater of the plant(COD=3100 mg/L / color=4500 Pt-Co) that would be produced after some foreseen cleaner production measures / caustic recovery and reusing of dyeing process wastewater. When applied to indigo-dyeing wastewater / ozonation provided 95% color and 61% COD removals at 1320 mg/h ozone dose within 60 minutes The optimum pH was evaluated as 4 when indigo-dyeing wastewater exposed to ozonation at different pHs(1.6-12.3). On the other side, ozonation applied as pre-treatment to the plant effluent provided 86% color and 46% COD removals with 3240 mg/h ozone dose in 70 minutes. Less satisfactory results were obtained when ozonation was tried in the wastewater after measures, with 86% color and 31% COD removals at 3960 mg/h ozone dose in 80 minutes. When applied to the biologically-treated effluent / at 420 mg/h ozone dose and within 40 minutes, ozonation removed 47% of influent COD and 96% of influent color indicating better performance of ozonation in postoxidation. In order to assess possible improvements on ozonation with the addition of H2O2, different concentrations were tried, but no significant improvement was obtained. The improvement in BOD5/COD index was also determined for the ozonetreated plant effluent to measure the effects of ozonation on biodegradability and found out that BOD5/COD ratio has improved to 0.39 from 0.22.

Magnetic nanoparticles have been used in many areas owing to their variable characteristic behaviors. Among these iron oxide nanoparticles are one of the mostly preferred type of nanoparticles. In this study Fe3O4, namely magnetite, which is one type of magnetic iron oxide nanoparticles was used. Magnetite nanoparticles with a narrow size distribution were prepared in aqueous solution using the controlled coprecipitation method. They were characterized by electron microscopic methods (SEM and TEM), crystal structure analysis (XRD), particle size analyzer, vibrating sample magnetometer (VSM) and Raman spectrometry. The nanoparticles were coated with a thin (ca 20 nm) silica shell utilizing the hydrolysis and the polycondensation of tetraethoxysilane (TEOS) under alkaline conditions in ethanol. The presence of silica coating was investigated by energy dispersive X-ray spectrometer (EDX) measurement. After surface modification with an amino silane coupling agent, (3-Aminopropyl)triethoxysilane, histidine was covalently linked to the amine group using glutaraldehyde as cross-linker. Carbonyl complexes of rhenium [Re(CO)3(H2O)3]+ was prepared through reductive carboxylation utilyzing gaseous carbon monoxide as a source of carbonyl and amine borane (BH3NH3) as the reducing agent. The complex formation was followed by HPLC- ICP-MS system and 95% conversion of perrhanete into the complex was achieved. The magnetic nanoparticles were then labeled with the Re complex with a yield of 86.8% through the replacement of labile H2O groups with imidazolyl groups. Thus prepared particles were showed good stability in vitro. Herein rhenium was selected as a surrogate of radioactive 99mTc. However radioactive isotopes of rhenium (186-Re and 188 Re) is also used for radioactive therapy.

Zeolite A membranes have great potential in pervaporation separation of ethanol/water mixtures with high flux and selectivity. Zeolite membranes usually synthesized from hydrogels in batch systems. In recent years, zeolite membranes are prepared in semicontinuous, continuous and recirculating flow systems to allow the synthesis of zeolite membranes with enlarged surface areas and to overcome the limitations of batch system at industrial level production. The purpose of this study is to develop a synthesis method for the preparation of good quality zeolite A membranes in a recirculated flow system from hydrogels and to test the separation performance of the synthesized membranes by pervaporation of ethanol/water mixture. In this context, three different experimental synthesis parameters were investigated with zeolite A membranes synthesized in batch system. These parameters were the composition of the starting synthesis hydrogel, silica source and the seeding technique. Syntheses were carried out using hydrogels at atmospheric pressure and at 95 &deg / C. The membranes were characterized by X-ray diffraction, scanning electron microscopy and pervaporation of 90 wt% ethanol-10 wt% water mixtures. v Pure zeolite A membranes were synthesized both in batch and flow systems. The membranes synthesized in batch system have fluxes around 0.2-0.3 kg/m2h and selectivities in the range of 10-100. Membranes with higher selectivities were obtained in batch system by using waterglass as silica source, seeding by dip-coating wiping method, and with a batch composition of 3.4Na2O:Al2O3:2SiO2:155H2O. The membranes prepared in flow system have higher pervaporation performances than the ones prepared in batch system in considering both flux and the selectivity. Fluxes were around 0.3-3.7 kg/m2h and selectivities were in the range of 102-104 for the membranes prepared in flow system which are comparable with the data reported in literature for batch and flow systems. A high quality zeolite A membrane was also synthesized from 3.4Na2O:Al2O3:2SiO2:200H2O hydrogel at 95 &deg / C for 17 hours in flow system. Pervaporation flux of this membrane was 1.2 kg/m2h with a selectivity &gt / 25,000 at 50&deg / C. Although the synthesis method is resulted with high quality membrane, reproducibility of the synthesis method is poor and it should be improved.