Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Author: search.filters.author.Polat, HürriyetSubject: search.filters.subject.Biopolymers

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  • Master Thesis
    Comparative Adsorption Studies of Heavy Metal Ions on Chitin and Chitosan Biopolymers
    (İzmir Institute of Technology, 2007) Keleşoğlu, Serkan; Polat, Hürriyet; Polat, Hürriyet; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    In this study comparative adsorption studies of heavy metal ions (Cu2+, Pb2+,Cd2+, Ni2+) on chitin and chitosan biopolymers were performed to investigate the uptake performances. For this purpose chitosan was prepared from chitin in controlled experimental conditions and then these biopolymers were characterized with Elemental Analysis, Viscosity, FT-IR, Potentiometric Titration, XRD, SEM, Zeta Potential,Particle Size Distribution and TGA/DTA measurements. Batch adsorption experiments were performed at eight different initial heavy metal ion concentrations (10, 25, 50, 100, 250, 500, 750, 1000 m/L), two different temperatures (298.15 K and 328.15 K), time period ranging from 5 minutes to 1 day and pH of solutions ranging from 1 to 7. The results indicated that the uptake performence of chitin and chitosan biopolymer significantly changed with pH, adsorbent dosage,concentration and temperature. In general, chitosan biopolymer demonstrated greater fixation abbility for heavy metal ions than chitin. However the fixation trend of heavy metal ions on chitin and chitosan biopolymers was the same (Cu2+ > Pb2+ > Cd2+ > Ni2+). Moreover Irwing-Williams Series support the dominancy of the binding mechanism for Cu2+, Cd2+ and Ni2+ ions on both biopolymers. Adsorption of heavy metal ions on both chitin and chitosan biopolymers followed pseudo second order kinetics with the rate constant indicating faster adsorption on chitin for Cu2+ and Pb2+ ions and faster adsorption on chitosan for Cd2+ and Ni2+ ions.Both of the Freundlich and Langmuir adsorption isotherms seem to adequately represent the adsorption data obtained in this study. The positive value of enthalpy change (Ho) and negative value of free energy change (Go) shows the adsorption process is endothermic and spontaneous. Moreover obtained positive entropy changes (So) show that an increase in randomness, is associating the adsorption of metal ions onto chitin and chitosan biopolymers.
  • Master Thesis
    Kinetics of Oil Dispersion in the Presence of Chitosan Based Biopolymers
    (Izmir Institute of Technology, 2009) Şen, Didem; Polat, Hürriyet; Polat, Hürriyet; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    This study was focused on the modification of chitosan to produce surface active biopolymers and their application as emulsifiers. Therefore N-acylation of chitosan was utilized. Characterization of the produced materials were achieved by the following ways; Ninhydrin assay, Elemental Analysis, Fourier Transform Infrared Spektroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), surface (or interfacial) tension and contact angle measurements. These characterizations provided information about the substitution degree, structure and the hydrophobic-hydrophilic properties of the produced surface active biopolymer. For example, the surface tension values were determined as decreasing from 71 mN/m to 40-50 mN/m in the presence of chitosan based bio-polymers with the substitution degrees between 25% and 45%. On the other hand contact angle values increased significantly in the case of chitosan based biopolymers. modifications with different initial mol ratios. The effect of these modified materials on the kinetics of oil emulsification was tested conducting in-situ size measurement studies and using a phenomenological dispersion model for the evaluation of data. This way the dispersion rate constants were able to calculated and used to compare the different conditions used to prepare emulsions. As a conclusion, the coalescence sub process that becomes dominant after 8 minutes of emulsification (in the case of oil only) totally disappeared in the presence of both chitosan and N-acylated chitosan. The rate of oil dispersion up to 8 minutes, however, did not change much in all the cases. The effect of modified chitosan on the kinetics was not significant. These were postulated as the possible changes in the configurations of the modified chitosan molecules due to the increased hydrophobic character and inter molecule interactions.