WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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  • Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Determining Water and Sediment Quality Related To Lead-Zinc Mining Activity
    (Polish Academy of Sciences, 2018) Şanlıyüksel Yücel, Deniz; Baba, Alper; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    This study focuses on the Koru and Tesbihdere Pb-Zn mining districts, located at the upstream areas of the Umurbey dam basin. Mining activities in Koru, one of the longest operated mines in NW Turkey, date back to the beginning of the 1900s. The purpose of the study is to (1) determine the hydrochemical properties of the water resources and to assess the potential environmental consequences of mining activities in the Koru and Tesbihdere mining districts, and (2) investigate the effects caused by mining activities on the water resources and sediment quality in the Umurbey dam basin. Concentrations of As, Cd, Cu, Fe, Mn, Pb, and Zn in river sediments downstream of the Tesbihdere and Koru mining district, and in the Umurbey dam sediments were higher than the world average for river sediments. The geoaccumulation index and enrichment factor revealed that sediments were strongly polluted with Pb and Zn, moderately to strongly polluted with Cd and moderately polluted with Cu. The chemical analyses of water resources revealed that the maximum Fe, Zn, Pb, Mn, and Cu concentrations reached 2890 μg/l, 1785 μg/l, 1180 μg/l, 984 μg/l, and 419 μg/l, respectively. The Koru River is classified as polluted water according to Turkish inland water quality regulations. The environmental contamination problems in the local drainage system are caused by leakage from past and current tailing ponds into the Koru River.
  • Article
    Citation - WoS: 15
    Citation - Scopus: 16
    Coke Content of Spent Commercial Fluid Catalytic Cracking (fcc) Catalysts: Determination by Temperature-Programmed Oxidation
    (Springer Verlag, 2003) Bayraktar, Oğuz; Bayraktar, Oğuz; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Zeolite catalysts are widely used in oil refinery and petrochemical industries. Fluid catalytic cracking (FCC) catalysts used in a refinery consist of Y zeolite, a silica-alumina matrix and a binder. In this study, spent FCC catalysts were prepared by cracking sour imported heavy gas oil (SIHGO) in a microactivity test unit. The total amount of coke and the hydrogen-to-carbon ratio (H/C) in the coke for spent FCC catalysts contaminated with metals were determined using temperature-programmed oxidation (TPO). Total H/C ratios of the coke on FCC catalysts were found to be in the range of 0.4 to 1, indicating the majority of the coke consists of polyaromatic species. H/C ratio decreased with increasing coke contents on the catalysts. This ratio was found to be higher for the catalyst with high metal concentration compared to the catalyst with relatively low metal concentration. The high H/C ratio for highly contaminated FCC catalyst was attributed to the formation of hydrogen rich coke by hydrogenation reactions catalyzed by the contaminant metals on the catalyst. After hydrogen pre-treatment both coke amount and H/C ratio decreased significantly. This was due to the decrease in the hydrogenation activities of the contaminant-metals in their reduced forms.
  • Article
    Citation - WoS: 29
    Citation - Scopus: 32
    Visualization of the Equilibrium Fcc Catalyst Surface by Afm and Sem-Eds
    (Kluwer Academic Publishers, 2003) Bayraktar, Oğuz; Bayraktar, Oğuz; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The deposition of metal contaminants (e.g., Ni, V, and Fe) from the hydrocarbon feed causes the deactivation of fluid catalytic cracking (FCC) catalyst used in petroleum refining. It is very important to understand the changes in the morphology and chemical composition on the catalyst surface and how these structural and chemical changes affect the catalyst performance. In this research, metal-contaminated FCC catalysts from a commercial unit have been characterized using AFM together with SEM-EDS. The AFM images showed the surface pores as well as the features that surround the pore's entrance on the catalyst surface. Catalyst surface contains debris that appear as bright spots in AFM images. SEM-EDS results have shown the presence of iron in these bright spots. Fe enrichment at the catalyst particle surface was also confirmed by XPS analyses.