EFFECTS OF Zn-DOPING ON THE PHOTOCATALYTIC ACTIVITY AND MICROSTRUCTURES OF NANOCRYSTALLINE SnO2 POWDERS | Author : Metin Yurddaskal, Serdar Yildirim, Tuncay Dikici, Melis Yurddaskal, Mustafa Erol, Idil Aritman, Hilmiye Deniz Ertugrul Uygun, Erdal Çelik | Abstract | Full Text | Abstract :In this study, undoped and Zn-doped SnO2 nanoparticles in different concentrations were synthesized by flame spray pyrolysis (FSP) technique. The produced particles were post-annealed after FSP process at 600 °C in order to obtain a crystalline structure. The structural analysis of the produced powders was performed by X-Ray Diffraction (XRD) methods. The surface morphology of the nanoparticles was identified using scanning electron microscopy (SEM). In addition, photocatalytic degradation of aqueous methylene blue (MB) solutions were evaluated using undoped and Zn-doped SnO2 nanoparticles under UV light illumination. Photocatalytic degradation of the MB solutions followed the pseudo-first-order-kinetics and the effect of the Zn doping amount on the photocatalytic reaction was investigated. |
| ENHANCED PHOTOCATALYTIC PROPERTIES OF Sn-DOPED ZnO NANOPARTICLES BY FLAME SPRAY PYROLYSIS UNDER UV LIGHT IRRADIATION | Author : Metin Yurddaskal, Serdar Yildirim, Tuncay Dikici, Melis Yurddaskal, Mustafa Erol, Idil Aritman, Erdal Çelik | Abstract | Full Text | Abstract :Zinc oxide (ZnO) is widely used in different areas thanks to its unique photocatalytic, optic and electrical properties. Sn doped ZnO nanoparticles were synthesized through flame spray pyrolysis (FSP) technique. The Sn dopant concentrations were 1, 3, 5, 7 and 9 at. % in produced ZnO nanoparticles. The structural analysis of the produced powders was performed by X-Ray Diffraction (XRD) methods. The surface morphology and particle size distribution of the nanoparticles were identified using scanning electron microscopy (SEM), and dynamic light scattering (DLS) techniques. In addition to this, produced photocatalysts were evaluated for degradation of aqueous methylene blue (MB) solutions under UV light irradiation. Sn-doped nanoparticles have superior photocatalytic activity compared to un-doped ZnO. |
| Colour Removal from Biologically Treated Textile Dyeing Wastewater with Natural and Novel Pre-Hydrolysed Coagulants | Author : G. Yildiz Töre, R Ata, S. Özden Çelik, S Kirhan Sesler | Abstract | Full Text | Abstract :
In this paper, natural (chitosan and starch) and novel pre-hydrolysed coagulants (PACl, PAFC, PFS and PFC) were performed with coagulant aid for colour removal from a biologically treated textile wastewater including multiple dyes (indigo and reactive). According to the experimental results, optimum coagulant dosages which provide the best colour removal for PACl, PAFCl, PFS (%10) and PFCl (%10), were determined as 80 mg/L, 10 mg/L, 3 mg/L and 40 mg/L, respectively, at pH 4 and pH 6,98 (natural pH of studied wastewater, pHnww). Maximum colour removal was determined as 97% for PAFCl, minimum removal was 23% for PFCl at pH 4, while it was calculated as 75% and 52% at pHnww. COD removal was observed as 45% at pH 4 and 55% at pHnww for maximum colour removal. Sludge production rate was measured as 71 kg/d while this rate was found as 60 kg/d at pHnww. On the other hand colour removal efficiencies were determined in the range of 55-88% at pHnww and pH 3 for chitosan while it was calculated as 52% for starch at pHnww and pH 9. According to the results, PAFCl and chitosan were found as the best coagulants for colour removal of investigated textile wastewater. According to the economic analysis results, the best colour effiency were found as 97% with PAFCl and the second best colour removal were found as 88% with Chitosan. Due to lower sludge production than PAFCl and lower chemical costs; Chitosan can be considered as a reasonable alternative for this wastewater.
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| PRODUCTION AND CHARACTERIZATION OF ACTIVATED CARBON FROM POMEGRANATE PULP BY PHOSPHORIC ACID | Author : Eylem PEHLIVAN | Abstract | Full Text | Abstract :In this study, samples of activated carbon were prepared from pomegranate pulp by chemical activation. H3PO4 was used as chemical activation agent and three impregnation ratios (50-100-200%) by mass were applied on biomass at impregnation times of 24 and 48 hours. Carbonization is applied to impregnated biomass samples under N2 sweeping gas in a fixed bed reactor at 500 and 700 °C. For determination of chemical and physical properties of the obtained activated carbons; elemental analysis was applied to determine the elemental composition (C, H, N, O) and FT-IR spectra was used to analyze the functional groups. BET equation was used to calculate the surface areas of activated carbons. For understanding the changes in the surface structure, activated carbons were conducted to Scanning Electron Microscopy (SEM). Maximum BET surface area (840 m2/g) was reached with the activated carbon generated using 200% H3PO4 impregnated biomass sample, at a carbonization temperature of 700 °C and impregnation time of 48 hours. Experimental results showed that impregnation ratio have a significant effect on the pore structure of activated carbon and pomegranate pulp seems to be an alternative precursor for commercial activated carbon production. |
| FENTON-LIKE OXIDATION OF REACTIVE BLACK 5 IN THE PRESENCE OF LABO3 (B: Fe, Co, Mn, Ni) PEROVSKITE CATALYSTS | Author : Burcu Palas, Gülin Ersöz, Süheyda Atalay | Abstract | Full Text | Abstract :The catalytic performances of LaBO3 (B: Fe, Co, Mn, Ni) perovskite catalysts in Fenton-like oxidation of the textile dye, Reactive Black 5 were compared, and, the optimum reaction conditions were investigated in the presence of the most efficient catalyst. Reactive Black 5 was selected as the model dye due to its complex chemical structure, high water solubility and common usage in the textile industry. The performances of the catalysts in Reactive Black 5 degradation and decolorization were compared by testing different catalyst loadings. According to the catalyst screening experiments, LaFeO3 showed the highest catalytic performance whereas LaCoO3, LaMnO3, and, LaNiO3 were not effective in the degradation and decolorization of Reactive Black 5. A parametric study was carried out in the presence of LaFeO3 catalyst in order to determine the most suitable reaction conditions. In the parametric study, the effect of catalyst loading, pH and the initial H2O2 concentration were investigated. The initial dye concentration and the reaction temperature were kept constant at 100 ppm and 50?, respectively. The most suitable reaction conditions were determined as 0.1 g/L of catalyst loading, 3 and 1 mM of H2O2, and, 96.9% degradation, and complete decolorization were achieved under these conditions. |
| NANO ZINC BORATE AS A LUBRICANT ADDITIV | Author : Sevdiye Atakul Savrik, Burcu Alp, Fatma Üstün, Devrim Balköse | Abstract | Full Text | Abstract :Lubricants consist of base oils and chemical additives such as dispersants, surfactants, oxidation inhibitors, and antiwear agents. Organic and inorganic boron-based additives increase wear resistance and decreases friction. Hexagonal boron nitride and metal borates are used for this purpose. Zinc borate is a synthetic hydrated metal borate. The production techniques of zinc borate generally include the reaction between zinc source materials (zinc oxide, zinc salts, zinc hydroxide) and the boron source materials (boric acid and borax). The nano zinc borate particles were prepared from zinc nitrate and borax in the present study by using low initial zinc and borate concentrations and low temperature to prevent particle growth. The templates span 60 and PEG 4000 were used to control the particle size. The particles were separated from mother liquor by centrifugation, washed with ethanol, dried and ground and used as additive to base oil. The particles have H2O and B(3)-O vibrations in their FTIR spectra. The empirical formula of the nanoparticles was approximately 3ZnO.2B2O3.4H2O from EDX and TGA analysis. X-ray diffraction diagram indicated the particles were in amorphous state. When the nanoparticles were added to light neutral oil the wear scar diameter and friction coefficient was lowered 50% and 20% respectively. |
| SYNTHESIS, CRYSTAL STRUCTURE, MAGNETIC PROPERTY, AND N2-GAS-ADSORPTION PROPERTY OF DINUCLEAR COPPER(II) 3,4,5-TRIMETHOXYBENZOATE | Author : Masahiro Mikuriya, Chihiro Yamakawa, Kensuke Tanabe, Daisuke Yoshioka, Ryoji Mitsuhashi, Hidekazu Tanaka, Makoto Handa | Abstract | Full Text | Abstract :Copper(II) 3,4,5-trimethoxybenzoate, [Cu2(3,4,5-(CH3O)3C6H2CO2)4 (CH3OH)2]·2DMF, was prepared and characterized by elemental analysis, infrared and UV-vis spectra and temperature dependence of magnetic susceptibilities (4.5—300 K). The crystal structure was determined by the single-crystal X-ray diffraction method. It crystallizes in the triclinic space group P1 with a = 8.2110(13) Å, b = 13.181(2) Å, c = 13.409(2) Å, a = 97.967(3)°, ß = 102.378(3)°, ? = 105.009(3)°, V = 1339.8(4) Å3, Dx = 1.465 g/cm3, and Z = 1. The R1 [I > 2s(I)] and wR2 (all data) values are 0.0363 and 0.0816, respectively, for all 5991 independent reflections. The crystal contains crystallographically centrosymmetric dinuclear molecule with axial methanol molecules and crystal DMF molecules [Cu···Cu 2.6190(6) Å]. Magnetic susceptibility data show a considerable antiferromagnetic interaction between the two copper(II) ions (2J = –292 cm–1). Gas-adsorption behavior was investigated for N2. |
| Enhancement of Cerium exchange with Ultrasound | Author : Fehime Çakicioglu-Özkan, Yasemin Erten-Kaya | Abstract | Full Text | Abstract :In this study the effect of ultrasound of the cerium exchange was studied. The results were compared to those obtained from traditional batch exchange method. Contact time, initial cation concentration (fold equivalent excess) and the types of the ultrasound were studied. Ultrasonic probe, which is the most effective method, enhanced the replacement of Na+ ion with Ce3+ ion in the extra-framework of zeolite up to 73 % by applying 5 consecutive ion exchanges. The cerium in the solution caused to be formed cerium oxides on the crystal surface occluding the pores. Thus the specific surface area of cerium exchanged zeolite was decreased due to formation of cerium complexes on the surface and into the pores. |
| Binder Effect on Electrochemical Performance of Zinc Electrodes For Nickel-Zinc Batteries | Author : Gizem Cihanoglu, Özgenç Ebil | Abstract | Full Text | Abstract :Polyethylene glycol (PEG) and polyvinyl alcohol (PVA) were used as a zinc electrode binder at different concentrations to enhance the electrochemical behavior of zinc electrodes for nickel-zinc (NiZn) batteries. ZnO powders synthesized by mechanochemical and hydrothermal precipitation methods were mixed with lead oxide, calcium hydroxide and binder to prepare zinc electrodes in pouch cell NiZn batteries. Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) analysis reveal that initial morphology of zinc electrode changes drastically regardless of the binder type and its loading after charge/discharge process, and even the charge/discharge process is not complete. The results show that the presence of PEG causes better discharge capacity compared to that of PVA as a binder. Zinc electrode prepared using commercial ZnO powder and 3 wt.% PEG gives the optimum discharge capability, with a specific capacity of approximately 311 mAhg-1, while zinc electrodes prepared using ZnO powder synthesized from ZnCl2 and Zn(NO3)2.6H2O and 6 wt.% PEG exhibit high specific energy of 255 and 275 mAhg-1, respectively. The results suggest a relationship between binder loading and battery capacity, but in-situ analysis of microstructural evolution of zinc electrode during charge/discharge process is needed to confirm this relationship. |
| EFFECT OF ANNEALING TEMPERATURES ON THE CRYSTALLIZATION AND PHOTOCATALYTIC ACTIVITY OF MICRO-NANOPOROUS TiO2 FILMS PRODUCED BY ELECTROCHEMICAL ANODIZATION | Author : Melis Yurddaskal, Metin Yurddaskal, Tuncay Dikici, Hülya Durmus | Abstract | Full Text | Abstract :In this study, micro-nanoporous TiO2 films were prepared by electrochemical anodization of titanium (Gr-2) in an aqueous solution containing 0.5 wt. % HF solution at a constant potential of 30 V and then annealed in ambient air at 500, 600, 700 and 800 °C for 2 h to obtain crystalline structures. The crystalline phase and surface morphology of the samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The photocatalytic performances of the samples were evaluated by the photocatalytic degradation of aqueous methylene blue (MB) solutions under UV light illumination for different periods. XRD results indicated that at annealing temperatures higher than 600°C, anatase started to transform into rutile. Increasing annealing temperatures resulted in reduced micro-nanopores diameter and increased wall thickness. At 800°C, the structure completely disappeared. The results demonstrated that changes in both the crystalline structure and surface morphology have a strong influence on the photoactivity of the nanostructured TiO2 films. |
| SIMULATION OF CO-CURED MULTI-CELL COMPOSITE BOX BEAM MANUFACTURING VIA VARTM | Author : Mert Akin, Merve Erdal | Abstract | Full Text | Abstract :Sub-structures of aircraft structures mainly consist of stiffened shells such as fuselage frames, ribs and multi-cell box beams. Conventionally, these stiffened shells are manufactured through a process wherein shells and stiffeners are fabricated separately and then are integrated either through mechanical fastening and adhesive bonding. Co-curing is an integral molding technique that can greatly reduce the part count and the final assembly costs for composite materials. This article presents a simulation of integral manufacturing of a three-cell composite box beam by vacuum assisted resin infusion process. To validate the model, the characterization tests of both resin and reinforcement materials were carried out. Porosity and permeability testing of the reinforcement materials were conducted. Moreover, the effect of stacking sequence and vacuum level on the preform porosity were investigated. Additionally, the resin viscosity measurements were performed and the influence of temperature and curing on resin viscosity were examined. Having obtained the characterization data, vacuum infusion model was validated using RTMWorx software and then simulation of a three-cell composite box beam was conducted. |
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