Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 12Citation - Scopus: 14Zinc Electrode Morphology Evolution in High Energy Density Nickel-Zinc Batteries(Hindawi Publishing Corporation, 2016) Payer, Gizem; Ebil, ÖzgençPrismatic Nickel-Zinc (NiZn) batteries with energy densities higher than 100 Wh kg-1 were prepared using Zn electrodes with different initial morphologies. The effect of initial morphology of zinc electrode on battery capacity was investigated. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) reveal that initial morphology of zinc electrode changes drastically after a few charge/discharge cycles regardless of initial ZnO powder used. ZnO electrodes prepared using ZnO powders synthesized from ZnCl2 and Zn(NO3)2 lead to average battery energy densities ranging between 92 Wh kg-1 and 109 Wh kg-1 while using conventional ZnO powder leads to a higher energy density, 118 Wh kg-1. Average discharge capacities of zinc electrodes vary between 270 and 345 mA g-1, much lower than reported values for nano ZnO powders in literature. Higher electrode surface area or higher electrode discharge capacity does not necessarily translate to higher battery energy density.Article Citation - WoS: 35Citation - Scopus: 41Batch and Column Studies on Heavy Metal Removal Using a Local Zeolitic Tuff(Elsevier Ltd., 2010) Balköse, Devrim; Ülkü, Semra; Can, ÖzgeIon exchange is considered to be one of the most cost effective methods if low cost ion exchangers such as natural zeolites are used in waste water treatment. In this study, a zeolitic tuff rich in clinoptilolite from Gördes Manisa Turkey was examined to evaluate its ion exchange performance for the removal of copper, nickel and cobalt ions from metal (II) nitrate solutions at various concentrations by performing both batch and packed column experiments. A clinoptilolite tuff with purity around 60% was used in ion exchange experiments. Copper, nickel and cobalt exchange capacities of the tuff were determined as 8.3mg (0.26meq) Cu2+/g, 6.6mg (0.23meq) Ni2+/g and 4.5mg (0.15meq) Co2+/g, respectively. The equilibrium behavior of the system was best described by classical Langmuir model. The experimental breakthrough curves from the column experiments were fitted to solid diffusion control model. The study showed that efficient metal ion removal can be done by using the local clinoptilolite rich tuff. © 2010 Elsevier B.V.Article Citation - WoS: 28Citation - Scopus: 37Bioleaching of Nickel From Equilibrium Fluid Catalytic Cracking Catalysts(Springer Verlag, 2005) Bayraktar, OğuzThis study investigates the possibility of reusing metal-contaminated equilibrium fluid catalytic cracking (FCC) catalyst after bioleaching. Leaching with Aspergillus niger culture was found to be more effective in the mobilization of nickel from the catalyst particles compared to chemical leaching with citric acid. Bioleaching achieved 32% nickel removal whereas chemical leaching achieved only 21% nickel removal from catalyst particles. The enhanced nickel removal from the catalysts in the presence of A. niger culture was attributed to the biosorption ability of the fungal mycelium and to the higher local concentration of citric acid on the catalyst surface. It was found that 9% of solubilized nickel in the liquid medium was biosorbed to fungal biomass. After nickel leaching with A. niger culture, the hydrogen-to-methane molar ratio and coke yield, which are the measures of dehydrogenation reactions catalysed by nickel during cracking reactions, decreased significantly.Article Citation - WoS: 24Citation - Scopus: 25Temperature-Programmed Reduction of Metal-Contaminated Fluid Catalytic Cracking (fcc) Catalysts(Elsevier Ltd., 2004) Bayraktar, Oğuz; Kugler, Edwin L.A temperature-programmed reduction study of equilibrium fluid catalytic cracking (FCC) catalysts has shown three hydrogen-consumption peaks associated with contaminanted metals. A low-temperature peak, located near 510°C, is produced by the reduction of several components in the catalyst. Highly-dispersed vanadium contributes to this peak. A high-temperature peak, located near 800°C, is produced by reduction of nickel aluminate or nickel silicate compounds. A linear relationship exists between the area of the high-temperature peak and nickel concentration on equilibrium catalysts. An intermediate-temperature peak, located near 690°C, appears to be related to some form of vanadium compound. The intermediate-temperature peak does not occur on low-vanadium-concentration equilibrium catalysts, but is observed at higher vanadium-contamination levels. The presence of the 690°C peak was found by deconvoluting hydrogen-consumption data. The existence of this intermediate-temperature peak was proven by external reduction of highly-contaminated equilibrium catalyst at 500 and 700°C. External reduction at 500°C removes the low-temperature peak from the temperature-programmed reduction (TPR) spectrum. External reduction at 700°C removes both the low-temperature and intermediate-temperature peaks from the TPR spectrum. The difference in spectrum between calcined and 700°C reduced samples shows a clear spectrum with only the low and intermediate-temperature peaks present.