ABSTRACT Toxicological studies have shown that the degree of toxicity of some elements depends on the chemical form in which the element is present. Chromium (III) is considered as an essential micronutrient for human whereas chromium (VI) is a potentially carcinogenic agent. So the speciation of inorganic chromium in environmental samples is required for accurate assessment of pollution levels. The chromium content in natural water is usually very low, and a preconcentration is often necessary prior to the determination. A sensitive and selective preconcentration and speciation procedure is developed for the determination of trace and ultra trace amounts of chromium species by utilizing chemiluminescence (CL) and flame atomic absorption spectrometric (FAAS) techniques. The performances of amino silica-gel, amino sol-gel, mercapto silica-gel beads and metal oxides for solid phase extraction of chromium are examined either in column or batch type studies. Considering the advantage of concentrating Cr(III) and Cr(VI) ions separately simply by adjusting the pH of the medium, amino silica-gel resin is chosen in this study. The influences of different experimental parameters on the separation and preconcentration of chromium species such as pH, eluent concentration, flow rate, particle size of the resin are investigated. Chemiluminescence detection studies are performed by using the catalytic effect of Cr (III) on the reaction between luminol and hydrogen-peroxide and Cr (VI) is detected after reduction to Cr (III). Luminol and H2O2 concentrations and the pH of the medium are optimized to increase the sensitivity of the system. Chemiluminescence is inherently a very sensitive technique. When a preconcentration step is included in the CL mesurement of very low concentrations of chromium is possible to determine. Indeed, a 25-fold enhancement in sensitivity of chromium ions is achieved after incorporating amino silane&ndash / gel colums in the system and 0.2 &amp / #61549 / g/L of chromium (corresponds to the concentration of chromium in natural waters) was measured. A fully automated FI-CL system is designed that allows all necessary operations to be performed on-line. This system allows the pre-conditioning of micro-columns with different buffer solutions / adsorption of chromium species in micro-columns / washing these columns to remove interfering matrix components / elution of the species with minimum volume / transporting the species and chemiluminescence reagents to the cell / and, finally, cleaning of all pertinent conduits in the FIA-system in order to prevent carry-over between individual samples.

GRAFT COPOLYMERIZATION OF p-ACRYLOYLOXYBENZOIC ACID AND p-METHACRYLOYLOXYBENZOIC ACID ONTO ISOTACTIC POLYPROPYLENE The monomers, p-acryloyloxybenzoic acid (ABA) and p-methacryloyloxybenzoic acid (MBA) were synthesized by condensation reaction of corresponding acid chlorides with p-hydroxybenzoic acid in alkaline medium. The polymerization of the monomers were studied by several techniques. Polyacryloyloxybenzoic acid (PABA) was obtained by &amp / #947 / -radiation induced, solution and bulk melt polymerization by initiation of dicumyl peroxide (DCP). Polymethacryloyloxybenzoic acid (PMBA) could be obtained by only bulk melt polymerization. The graft copolymerization of the monomers onto isotactic polypropylene, IPP, was successfully carried out only with bulk melt polymerization. The IPP used in the graft copolymerization was firstly subjected to &amp / #947 / -radiation to create active sites for grafting. The graft copolymerization of the monomers, ABA and MBA onto IPP were initiated by these active sites. The grafting was studied at constant concentration of the monomers in the reaction mixture (50%) and at different reaction temperatures (170, 185, 202, 215 and 225&deg / C). The maximum grafting of PABA and PMBA were found to be 33.1% and 33.9% in the graft copolymers, respectively. The maximum grafting was reached in shorter times at higher temperatures, and it also increased with the increase of concentration of the monomers in the reaction medium. The graft copolymerization was also carried out by using initiator, DCP at 170&deg / C, however, the grafting extent was lower due to the homopolymerization of the monomers and the direct reactions between peroxides of initiator and peroxides on IPP. The graft copolymers were characterized by several techniques, DSC, WAX, TG/IR, MS, SEM and mechanical testing. The formation of both crystalline forms of (&amp / #61537 / 1 and &amp / #61537 / 2) were observed in the products obtained at 170&deg / C. The graft copolymerization of ABA did not have any significance on the formation of both forms of &amp / #61537 / form, while MBA lead to increase in &amp / #61537 / 2 form. The &amp / #61538 / crystalline modification formed in PABA-g-PP products obtained at 185&deg / C and at higher temperature and also in the second run of DSC studies after fast cooling. &amp / #61538 / form was not observed in graft copolymers of PMBA The decomposition mechanism of PABA, PMBA and the graft coproducts were studied by mass spectrometry and TG/IR. The polymers degraded predominantly by decomposition of side groups giving phenol, benzoic acid, hydroxybenzoic acid, carbondioxide and cyclodiene mainly. The mechanical properties of the graft copolymers showed an improvement particularly in tensile strength and modulus. The maximum tensile strength and modulus of PABA-g-PP were found as 41.1 and 881 MPa, and the values of PMBA-g-PP were measured as 35.9 and 721 MPa, respectively. These values were 28.1 and 486 MPa for irradiated IPP and 33.9 and 632 MPa for virgin IPP, respectively. The copolymerization of ABA did not alter the impact properties of the graft copolymer, while a slight decrease was observed in PMBA-g-PP samples. The tensile and impact fractured surface of the graft copolymers studied by scanning electron microscopy showed homogeneous structure. The brittle nature with some extent of ductility was seen in the samples.

Solvent recovery is gaining importance in the chemical production processes to reduce the costs and because of environmental concerns. Therefore separation schemes for recovery and recycle of solvents used in printing and packaging industry were developed. However, a low value by-product, mainly ethyl alcohol and isopropanol, is obtained during the solvent recovery process. If the water concentration of this mixture is decreased below 0.1% by weight, the value of it increases significantly. To dehydrate this stream, a pervaporation-adsorption separation scheme is developed in this study. The effect of pervaporation process parameters, such as temperature, feed flow rate, permeate side pressure, feed water and ethyl acetate concentration, on the performance of the PERVAP 2211 and 2201 membranes of Sulzer Chem-tech&reg / using the real industrial by-product solution obtained from a local company are investigated. Pervaporation tests were conducted using a home made experimental setup equipped with 148 cm2 rectangular shaped membrane module. Permeates obtained from these experiments were analyzed using a gas chromatograph equipped with FID and the water concentration of the feed solutions were analyzed using Karl-Fisher titration. Besides, adsorption studies were conducted using zeolite 3A in a fixed bed column. As a result of this study, PERVAP 2201 membranes showed higher fluxes with a slightly lower permeate water concentration compared to PERVAP 2211 at the at ranges studied. The increase in the pervaporation performance was observed with an increase in the temperature, permeate side vacuum and feed flow rate over the membrane. Therefore, concentrated-mode experiments were conducted at 70&deg / C, 2 torr permeate side pressure and 1.6 L/min of feed flow rate using the findings of the parametric studies and the retentate of this experiments were further dehydrated using liquid phase adsorption. Finally, the water concentration of the solution was decreased to 0.04% by weight.

Chiral hydroxylated cyclopentane derivatives are important precursors for biologically active compounds. Synthesis of these types of compounds in optically pure form found increased interest in pharmaceutical chemistry. 2-ethyl-cyclopentane-1.3-dione was acetoxylated using manganese III acetate at preferred positions. Enzyme catalyzed enantioselective hydrolysis or enantioselective acetoxylation of hydrolyzed acetoxy derivatives gives the corresponding hydroxylated diketones in optically pure form.

The hydrothermal and solid state methods were used in the synthesis of some aluminoborophosphate compounds. The products were investigated by using XRD, IR, DTA, DSC, ICP and SEM methods. The solid state reactions have been studied in the range 700 &ndash / 1200&amp / #61616 / C. Using several hydrothermal methods a novel aluminum phosphate compound Al3-xBxP3O12 was synthesized. The crystal system was found to be tetragonal with a=17.1629 and c = 12.6084A&deg / unit cell parameters and space group is P4212 (No:90). In anorthite mineral (CaAl2Si2O8) by replacing two silicon with boron and phosphorus, a boron containing anorthite with the formula of CaAl2BPO8 was prepared. The indexed data was reported for the first time in this thesis. Its crystal system was found to be monoclinic with the following unit cell parameters and &amp / #946 / angle / a=10.0440&Aring / , b = 12.6587 &Aring / , c = 14.4332 &Aring / and &amp / #946 / = 91.55&deg / . In this study, AlPO4.xH2O was also obtained by a hydrothermal method while trying to synthesize AlBP4O13. All the prepared compounds have been investigated by IR spectroscopy and the assignment of the functional B-O and P-O groups were done.

The synthesis and characterization of two donor acceptor type conjugated polymers were investigated. The electrochemical properties were examined using cyclic voltammetry, spectroelectrochemistry and kinetic studies. The increase in the alkyl chain length attached to the fluorene unit was investigated by the corresponding electrochemical characteristics. The synthesis was carried out via Stille coupling of 4,7- dibromo-4&#039 / -(tert-butyl)spiro[benzo[d]imidazole-2,1&#039 / cyclohexane] and 2,5- bis(tributylstannyl)thiophene with 9,9-dihexyl-9H fluorene and 9,9-didodecyl-9H fluorene respectively. Both of the polymers were neutral state green polymers. They had optical band gaps of 2.46 and 2.54 eV respectively. Increasing the chain length resulted in an increase in solubility and processibility of the polymer but also an increase in the band gap. This was due to the increased bulkyness of the alkyl group, leading to a decrease in the effective conjugation and planarity. They both had distinctive &pi / -&pi / * transitions, band structure and backbone that provides oxidative doping. P1, with the shorter alkyl chain had a lower oxidation potential than P2. Neither of the polymers was capable of being n-doped. They were both multichromic, revealing colors from neutral state green to doped state blue.

Aminoalcohols are very important compounds used in various asymmetric transformations as chiral ligands or chiral auxiliaries. In this thesis, four novel heterocyclic amine substituted chiral 1,4-aminoalcohols were synthesized. In the synthetic strategy, amide esters were synthesized from (2S, 3R)-3-methoxycarbonylbicyclo[2.2.1]hept-5-ene-2-carboxylic acid by DCC coupling method. Subsequent reduction of these amide esters lead to target 1,4-aminoalcohols. The activities of these novel chiral 1,4-aminoalcohols were tested in enantioselective diethylzinc addition, Mukaiyama aldol and Diels-Alder reactions. The enantioselectivities were measured by HPLC. All the products were identified by H NMR and C NMR spectroscopy

This thesis aims to investigate structural, optical and photoelectrochemical behavior of CdS nanowires and their heterojunctions with CdTe and polypyrrole nanowires. In the first part, CdS nanowires have been synthesized via electrochemical template-based route. It has been observed that synthesis conditions, such as bias voltage and deposition time, affect the morphology, optical and photoelectrochemical characteristics of CdS nanowires. Depending on the deposition time, length of the CdS nanowires changed from 100-200 nm to 3-4 m. Also the diameter of the nanowires increased with increasing the deposition time. Structure of the CdS nanowires has been confirmed by X-ray diffraction spectrometry and EDX analysis. Phototelectrochemical performances of the CdS nanowires have been changed dramatically with bias voltage and deposition time.In the second part of this thesis, CdTe nanostructures have been deposited on CdS nanowires. Change in optical and photoelectrochemical behavior of CdS nanowires after CdTe deposition has been investigated. Organic semiconductors and their composites with inorganic materials have been gaining attention due to tunable optical, electrical and magnetic properties. Also, ease of fabrication techniques, and therefore, low cost made these materials attractive for lots of applications including photovoltaic devices and flexible electronics. In the last part of this thesis, heterojunctions of CdS and Polypyrrole (Ppy) nanowires have been synthesized. Like CdS/CdTe heteronanostructures, first the CdS nanowires have been electrochemically deposited in anodized alumina template and then Ppy has been successfully deposited on CdS nanowires. In order to investigate the effects of polypyrrole synthesis conditions on CdS/Ppy heteronanostructures, CdS nanowire synthesis conditions have been kept constant. It has been observed that morphology and photoelectrochemical behavior of the Ppy nanowires has been affected from Ppy synthesis conditions. The photoelectrochemical performance changes of CdS/Ppy heteronanostructures have been also investigated in this part.

Electrolyte and pyrotechnic pellets are two important components of thermal batteries. Both electrolyte and pyrotechnic pellets are produced by cold compaction of constituent powders. These compacts are integrated in the battery as pellets with sufficient green density, green strength, calorific energy and burning rate (for pyrotechnic only) to provide high performance batteries. In this study, effects of physical properties of the used powders such as particle size distribution, average particle size, particle shape and composition of components and applied compression pressure and their interactions on green density and green strength of electrolyte pellets and in addition, calorific energy and burning rate of pyrotechnic pellets were examined. Statistical experimental designs were constructed to investigate the main and interaction effects of studied variables. 24 two factorial statistically designed experiments&rsquo / results for pyrotechnic pellets exhibited that the compression pressure and iron powder morphology were the most significant factors improving green density and break strength of pyrotechnic pellets. It was shown that the compression pressure had a negative effect on burning rate. Both calorific output and burning rate were increased significantly by increasing KClO4 fraction. In addition, decreasing particle size of KClO4 had also a positive effect on burning rate. The maximum calorific output was obtained at maximum KClO4 fraction. 23 two factorial statistically designed green strength and green density experiments&rsquo / results of electrolyte pellets revealed that, compression pressure was again the dominating factor. Moreover, there was a tendency for higher green density with lower MgO fraction and electrolyte powder average particle size. Besides, the positive effect of decreasing average particle size on green strength was investigated distinctly at low green density values. From the thermal battery perspective, main and interaction effects of variables on the characteristics of electrolyte and pyrotechnic pellets were successfully examined.

New iron phosphate and borophosphate compounds were synthesized and characterized by single crystal/powder X-ray diffraction, infrared spectroscopy, raman spectroscopy, thermogravimetric analysis, electron microscopy and elemental analysis. Using several compositions, Fey B(PO4)x type of compounds were attempted to be prepared by solid state reactions. The solid state reactions of boron compounds with a phosphating agent has been completed at 950oC. A new product Fe2BP3O12 is synthesized and indexed in this work which is isostructural with Cr2 BP3O12 A single crystal of iron ammonium phosphate, (NH4)3-xHxFeP3O12, was synthesized by a hydrothermal method and characterized. Its X-ray powder diffraction pattern was indexed in orthorhombic system. The unit cell parameters were found to be as a = 7.775 (&Aring / ), b = 7.445(&Aring / ), c = 14.331(&Aring / ) The compound with the formula NH4FeBP2O8OH was synthesized by hydrothermal method. Its X-ray powder diffraction pattern was indexed in monoclinic system. The unit cell parameters were found to be a = 9.336, b = 8.278, c =9.642&Aring / , and &amp / #946 / = 101.60o, which are good agreement with the literature values. Ferro-axinite type of compound was discovered as single crystals resembling the axinite mineral. The compound was indexed in triclinic system with the unit cell parameters of a = 7.167, b = 8.840 , c = 9.455&Aring / , &amp / #945 / = 64.83o, &amp / #946 / = 64.83o, &amp / #947 / = 69.42o. A zeotype Fe(H2O)2BP2O8.H2O, which was obtained by hydrothermal methods before, was synthesized by a precipitation method using different initial reactant. In this case, instead of Fe+2, Fe+3 compound was used as a reactant. All the compounds have been investigated by FTIR spectroscopy and the assignments of the functional BO3, BO4 and PO4 groups have been done.