Sürdürülebilir Yeşil Kampüs Koleksiyonu / Sustainable Green Campus Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7755

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Publisher: search.filters.publisher.Izmir Institute of TechnologySubject: search.filters.subject.Zeolites--Absorption and adsorption

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  • Master Thesis
    Investigation of Fuel Oxygenate Adsorption on Clinoptilolite Rich Natural Zeolite
    (Izmir Institute of Technology, 2006) Yetgin, Senem; İnal, Fikret; İnal, Fikret; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The wide use of fuel oxygenates in gasoline as anti-knocking and emission reduction agent have recently led to serious environmental concerns due to their detection in groundwater and surface water. Among the various gasoline additives, methyl tertiary butyl ether (MTBE) and ethyl tertiary butyl ether (ETBE) are the most frequently used fuel oxygenates worldwide. Due to the physical and chemical properties of fuel oxygenates, the conventional treatment technologies are generally ineffective for their removal from contaminated water. Adsorption is a common process frequently used to remove fuel oxygenates from water. The use of natural zeolites as adsorbent have increased significantly because of their availability and low cost. Clinoptilolite is one of the most abundant zeolites in nature, and Turkey has very large clinoptilolite reserves. In this project the adsorption properties of clinoptilolite rich natural zeolites for use in the removal of MTBE and ETBE from water have been investigated using batch equilibrium and fixed-bed column experiments. The adsorption properties have been compared with those of two activated carbons (i.e., Powdered Activated Carbon (PAC) and Granulated Activated Carbon (GAC)). In addition, bisolute (i.e., benzene and oxygenate) adsorption experiments were also carried out to determine the effectiveness of these adsorbents in the presence of other gasoline hydrocarbons. All the experiments were performed at 25 °C with initial oxygenate and benzene concentrations of 2000 ppb and 400 ppb, respectively. In batch equilibrium experiments, it has been found that the powdered and granulated activated carbons had higher adsorption capacities for MTBE and ETBE than clinoptilolite. The highest capacity for the amount of MTBE adsorbed per unit mass of adsorbent was achieved using GAC while that of ETBE was obtained using PAC. The presence of benzene decreased the adsorption capacities of GAC and PAC. However, the effect of benzene was not clear and was dependent on the adsorbent loading for clinoptilolite. In fixed-bed column experiments, GAC and clinoptilolite were tested as adsorbents. The column breakthrough curves for clinoptilolite were steep indicating fast adsorption and narrow mass transfer region. For GAC, mass transfer regions were wider due to the relatively flat breakthrough curves. There was no significant effect of benzene on the breakthrough curves for GAC and clinoptilolite.
  • Master Thesis
    Removal of Hydrocarbons From Wastewaters
    (Izmir Institute of Technology, 2002) Koltuksuz, Gülsan; Ülkü, Semra; Ülkü, Semra; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Wastewater of chemical industries and petrochemical spills are the main sources of hydrocarbon pollution. Benzene, toluene and o- xylene are generally found in petrochemical spills which effect the all livings in the environment because of its toxicity.This thesis was an investigation of benzene, toluene and o- xylene (nonpolar aromatics) adsorption on clinoptilolite rich natural zeolite and surfactant modified zeolite. The aim of surfactant modification was to make highly polar zeolite surface hydrophobic and thereby remove the hydrophobic benzene, toluene and o- xylene molecules from the aqueous phase with the help of hydrophobic attraction forces.Cationic surfactants Dodecyl Amine (DA), Tetramethylammonium (TMA+) and an anionic surfactant Sodium Dodecyl Sulfate (SDS) were used for surface modification.The degree of surface hydrophobicity was examined by calculating the change in Gibbs free energy of the zeolite-water system by using the contact angle and surface tension measurement results in the presence and absence of surface modification. For natural zeolite the mean contact angle value was found 7.76o. Modification by DA and TMA+ increased .m from 7.76o to 51.13o and 29.37o respectively at a concentration of M. In case of SDS, at the pH value of 4, there was only a slight increase from 7.76 o to 18.03 o at a concentration of M. Effect of these surfactants on interfacial tension at air water interface was also different from eachother. DA decreased the surface tension from 72.8 to 37 dynes/cm while TMA+ did not bring any change. This part of the study showed that the presence of surfactant makes zeolite surface more hydrophobic.In adsorption studies, natural zeolite removed 20% of hydrocarbons from water. Except toluene, there was an optimum time that the removal was high. Presence of surfactant was able to increase this percent up to 40% under some conditions depending on the surfactant and hydrocarbon type and concentration. The highest benzene adsorption was obtained with TMA+ modified zeolite. The sequence was benzene > toluene > o-xylene. In case of DA modified zeolite, on the other hand, oxylene was adsorbed more than the other hydrocarbons. The removal follows the order o- xylene > toluene > benzene in this case.