Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Characterization of the Adsorption Behaviour of Aqueous Cd (ii) and Ni (ii) Ions on Nanoparticles of Zero-Valent Iron(Izmir Institute of Technology, 2008) Efecan, Nazlı; Shahwan, Talal; Shahwan, TalalIron nanotechnology is recently concieved as a promising tool in environmental remediation. By virtue of their high surface/volume ratio, iron nanoparticles were shown to demonstrate outstanding sequestration capacity for various organic and inorganic pollutants.In this work iron nanoparticles were synthesized using the borohydride-reduction method. The obtained material showed chain like morphology, with the diameter of the nanoparticles being with in 20-80 nm range. HR-TEM images showed that the nanoparticles have a core-shell structure, with the core containing iron in its zero-valent state, while the shell is composed of iron oxides (Fe2O3, Fe3O4, FeOOH)and is generally < 3 nm in thickness.Nano-sized zero valent iron (nZVI) was then tested as a sorbent material for aqueous Cd2+ and Ni2+ ions. The uptake of these ions was investigated under various experimental conditions like time, concentration, pH, repititive application, and liquid/solid ratios. In addition, the uptake of these ions was compared with that of Cu2+, Zn2+, and Sr2+ in order to assess the effect of the reduction potential on the extent of removal.The results showed that nZVI is a very effective sorbent in terms of both kinetics and capacity of removal of the ions. Under the investigated conditions, the uptake reached equilibrium in less than one hour of contact time. Up to the initial concentration of 500 mg/L, the ions were removed almost completely utilizing an nZVI amount of 0.025 g and a solution volume of 10 ml. According to XRD and XPS results, both of Cd2+ and Ni2+ ions were fixed by nZVI through a non-reductive mechanism, that seems to be dominated by interaction of these ions with the exposed iron oxyhydroxide groups at the interface with the solution.Master Thesis Synthesis and Characterization of Clay-Supported Naoparticles of Zero-Valent Iron and Its Application for the Removal of Aqueous Co2+ and Cu2+ Ions(Izmir Institute of Technology, 2008) Üzüm, Çağrı; Shahwan, TalalIn recent years Permeable Reactive Barriers (PRBs) are being developed and used in the removal of organic and inorganic pollutants from surface water and groundwater. Zero-valent iron is viewed as an ideal reactive material for PRBs by means of its high sorption/reduction capacity towards various toxic ions. Zero-valent iron synthesized in nanoscale has a greater affinity to reduce/adsorb various toxic aqueous ions by virtue of its large surface area.In this work, nanoscaled (10-100nm) zero-valent iron (nZVI) was synthesized in ethanol by borohydride reduction method in atmospheric conditions. It was observed that iron nanoparticles are mainly in zero-valent oxidation state and that they remain without significant oxidation for weeks. To enhance its effect and usability, nZVI was supported by kaolinite and montmorillonite during synthesis. Characterization of those clay-supported nZVI was performed using XRD, SEM, TEM, EELS, XPS, Zeta Meter, BET-N2. Iron nanoparticles consist of a zero-valent core and a surrounding oxide shell with approximate thickness of 3-5 nm. The application of clays as support materials have led to a partial decrease in the aggregation of iron nanoparticles known to normally form chain-like structure. The diameter of unsupported iron nanoparticles was predominently within the range 20-80 nm, while clay-supported iron nanoparticles existing as dispersed nano spheres had particle diameters within 10-50 nm.The synthesized materials were applied as adsorbents for Co2+ and Cu2+ ions. According to the results , unsupported and clay-supported nZVI has a great capacity to immobilize Co2+ and Cu2+ ions with very fast kinetics. While Co2+ seems to be fixed via the oxohydroxyl groups on the surface of iron nanoparticles, Cu2+ was fixed by a redox mechanism that lead to formation of Cu2O and Cu0. The performed studies indicate that kaolinite- and montmorillonite-supported zero-valent iron nanoparticles are promising reactive materials for environmental applications.