Master Degree / Yüksek Lisans Tezleri
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Master Thesis Synthesis of Ni and Zn Based Organic Frameworks as Photocatalyst(Izmir Institute of Technology, 2019) Dikmen, Merve; Çakıcıoğlu Özkan, Seher FehimeNickel (Ni) and zinc (Zn) based organic frameworks were synthesized on the synthetic zeolite (5A and 13X), natural zeolite mineral clinoptilolite, -Alumina. Initially the zeolite surface was modified or seeded with metal organic framework (MOF). MOF-zeolite composite materials were characterized with XRD, SEM and ATR-IR to understand whether surface processes was achieved successfully or not. Additionally, band gap energies were evaluated to understand these composite materials were used as photocatalyst. Surface modification with APTES was not affect surface of the zeolites. In spite of that seeding created a layer on the surface of zeolite. Nickel based organic framework was coated onto the surface of modified 5A surface. Hydrothermal ZIF8 (ZIF8(1)) and solvothermal ZIF8 (ZIF8(2)) were synthesized successfully as MOF crystals. Besides ZIF8(2) was coated onto the surface of natural zeolite. Additionally, ZIF8/CuBTC sample were synthesized, seeded and coated onto the surface of natural zeolite. Band gap energies of the MOFs and composite materials were calculated with Tauc plot. Results showed that UV light can be used as light source for photocatalytic reactions of these photocatalysts. Also increasing photocatalyst amount increased dye degredation under UV light.Master Thesis Cation Exchange (ag+, Zn2+, Cu2+) Behavior of Natural Zeolites(01. Izmir Institute of Technology, 2001) Top, Ayben; Ülkü, SemraIn this study, clinoptilolite, most abundant zeolite present in nature, was proposed as a low cost antibacterial material. As a preliminary work, antibacterial activities of the original, Ag, and Zn forms of the clinoptilolite were investigated against several strains and compared to the commercial antibiotics. No antibacterial action was observed for the original clinoptilolite. Ag loaded clinoptilolite was found to be superior to the Zn-form against Proteus spp. and Pseudomonas aeruginosa.The original, Na, Ag, Zn, and Cu forms of the clinoptilolite samples were characterized by FTIR spectroscopy, thermal analyses (TGA, DTA, and DSC), and N2 physisorption studies. Specific attention was given in to the chemical analysis of the clinoptilolite by ICP-AES. Using the standard addition method, the respective idealized formulas of the original and Na-clinoptilolite based on 72 oxygen atoms in the unit cell were calculated as:(Na0.816 K2.070) (Ca1.060 Mg0.264) (Al5.653 Fe0.390) (Si30.084) O72. 20.023 H2O, and (Na4.763 K1.057) (Ca0.076 Mg0.094) (Al5.843 Fe0.221) (Si29.911) O72.17.049 H2O.In the FTIR spectra of the original and exchanged forms of the clinoptilolite, considerable shifts (from 3460 to 3494.8 cm-1) were observed in the band, which is formed due to the interactions of water molecules with the framework via hydrogen bonds. The positions of the other bands were not affected by cation exchange significantly. From the TGA curves, the water contents ranged between 14.31 and 11.00 % for the original and the cation-exchanged forms of the clinoptilolite. Mainly, two endotherms and one exotherm were obtained in the DTA curves. The first endotherm occurred up to about 150 oC, the second endotherm lied between 200 and 700 oC, and the exotherm was obtained at about 850 oC. Significant differences observed between the shapes of the DSC curves indicated that the cations control the dehydration behavior of the samples. N2 physisorption isotherms of five samples were all, Type IV with BET surface areas ranging between 34.97 and 46.76 m2/g.Ag, Zn and Cu ion exchange equilibria were investigated at 25 oC for both the original clinoptilolite and Na-clinoptilolite. In the former case, from the plateau of the isotherms cation exchange capacities were determined as 1.184, 0.439, 0.539 meq/g clinoptilolite for Ag+, Zn2+, and Cu2+ respectively. The major portion of the exchanges was contributed by Na+ and Ca2+. Distribution coefficient values indicated that at Ag, Zn and Cu ion exchange equilibria were investigated at 25 oC for both the original clinoptilolite and Na-clinoptilolite. In the former case, from the plateau of the isotherms cation exchange capacities were determined as 1.184, 0.439, 0.539 meq/g clinoptilolite for Ag+, Zn2+, and Cu2+ respectively. The major portion of the exchanges was contributed by Na+ and Ca2+. Distribution coefficient values indicated that at relatively low initial concentrations, the preference of the clinoptilolite for Zn2+ and Cu2+ was significant. At higher concentrations, higher distribution coefficients were obtained for Ag+ compared to Zn2+ and Cu2+. Langmuir and Freundlich models were applied for each equilibrium data. For Zn2+ and Cu2+ exchanges, Langmuir model gave better correlation and Freundlich model fitted experimental data slightly better in the case of Ag+ exchange.Equilibrium isotherms for Ag+-Na+, Zn2+-Na+, and Cu2+-Na+ pairs were investigated. Silver exchange isotherm lied above the diagonal over the whole composition range. For zinc and copper exchanges, the isotherms were above the diagonal up to equivalent fractions of exchanging ion in solution phase (As) at about 0.2. While full exchange was attained for silver, partial exchanges were obtained in the case of zinc and copper. The standard free energy of exchange values were found as .6.0, 2.03 and 3.09 kj/equiv for Ag+-Na+, Zn2+-Na+, and Cu2+-Na+ pairs respectively. From these values selectivity sequence was obtained as Ag+ > Na+ > Zn2+ > Cu2+.Consequently, by considering the preliminary antibacterial activity results, specific cation exchange capacities, and selectivity sequence of the clinoptilolite, Ag-clinoptilolite seemed to be promising antibacterial material. The results of the current study compared to the literature data pointed out that cation exchange behavior of the clinoptilolite is dependent on its original cationic composition. Therefore, it is necessary to carry out specific studies on representative samples from the deposit before any practical application.Master Thesis Investigation of Catalytic Activity and Selectivity of Pd and Ni Loaded Clinoptilolite Rich Natural Zeolite for Citral Hydrogenation(Izmir Institute of Technology, 2002) Uçar, Şule; Yilmaz, SelahattinThe preparation of active and selective clinoptilolite rich natural zeolite supported palladium and nickel catalysts for the liquid phase hydrogenation of citral was investigated. The catalysts were prepared by impregnation and ion exchange methods. Catalytic activity and selectivity tests were performed in a semi-batch reactor for different calcination temperatures, pressures, stirring rates, reaction temperatures, amount of catalysts, ethanol sources, catalyst metal loadings and catalysts preparation methods. Catalyst deactivation was also investigated. The characterization results showed that clinoptilolite was the major mineral in natural zeolite used as catalyst and catalyst support. It was thermally stable up to 440°C and its stability improved with Pd and Ni loading. Catalysts with loading of 0.72, 2.42, 5.63 % Pd and 3.12 % Ni were prepared by impregnation method. One catalyst was prepared by Pd ion exchange (5.66 %). Surface areas of the catalyst samples changed with calcination temperature, method of metal loading, amount of metal loading. A calcination temperature of 430°C and catalyst metal loading of 2.42 % Pd provided the largest surface area (38.96 m2/g) among the catalysts prepared by impregnation. The catalyst prepared by ion exchange had a much more larger surface area (49.46 m2/g) than those prepared by impregnation. The product distribution changed with catalysts prepared by different methods, catalyst metal loadings, catalyst calcination temperatures and reaction temperatures. The results showed that the Pd catalyst prepared by impregnation favoured the hydrogenation of the conjugated double bond of citral, giving citronellal as the primary hydrogenation products, whereas the amounts of unsaturated alcohols were very minor. High selectivity to citronellal was obtained for the catalyst calcined at 430°C containing 2.42 % Pd. The product distribution and the reaction rates were affected significantly by the reaction temperature (80, 100 and 120°C). The highest selectivity to citronellal (88 %) and the yield of citronellal (87 %) were obtained at 120°C. Higher reaction rates were observed as temperature increased. Increasing the amount of the catalyst in the reaction medium (150, 250 and 400 mg/100mL) affected the reaction rates, selectivity and the yield of citronellal. The highest amount of citronellal yield (91 %) was obtained when the reaction was carried out in the presence of the largest amount of the catalyst (400 mg/100 mL) used in this study. Different product distributions were obtained with various ethanol sources. Higher yields and selectivities were obtained with more pure solvent. Product distribution changed with catalyst metal loading. First increased significantly by changing catalyst loading from 0.72 to 2.42 % Pd and then rised slowly when metal loading changed from 2.42 to 5.63 % Pd. This was attributed to active metal surface area and its dispersion. Impregnated Pd catalysts regained their activities and selectivities upon regeneration. Ni impregnated catalyst showed a different product distribution. It showed a lower activity for a given temperature. Overall selectivities of the best Pd catalyst and Ni catalysts were similar. Pd catalyst prepared by ion exchange gave different products and its selectivity to citronellal was the lowest. This was attributed to the metal and catalyst surface interactions.Master Thesis Physicochemical Characterization of the Sorption Behavior of Cs+ and Sr2+ Ions on Natural Kaolinite and Cliptilolite Minerals(Izmir Institute of Technology, 2005) Akar, Dilek; Shahwan, TalalIn this study, aspects of the thermodynamics and kinetic profile of the sorption behavior of Cs+ and Sr2+ ions on natural minerals of kaolinite and clinoptilolite originating from Sındırgı and Manisa regions were investigated.Radioactive wastes that are caused by the increasing usage and production of radioactive substances give rise to big problems rising day by day. Natural substances such as clay minerals and zeolites decrease the dispersion of radioactive isotopes by sorption. Therefore they can be able to retard the radioactive pollution that is caused by radioisotopes, and the reach of these radioisotopes to the underground waters. 137Cs (t1/2 . 30.1 y) and 90Sr (t1/2 . 28.8) are radioisotopes that are important as radioactive wastes due to their long half-lives ,and that produce with high yields at the end of nuclear fission reactions. The experiments were performed using the batch technique at four different initial concentrations, two different temperatures, and time period ranging from 5 minutes up to 48 hours.The experimental findings revealed that the percentage sorption of Cs+ on clinoptilolite ranged 91-94, on kaolinite ranged 28-40 , and that the percentage sorptionof Sr2+ clinoptilolite ranged between 48-93 and 12-47 for the kaolinite case. In order to check the stability of sorption of Sr2+ and Cs+ ions fixed by kaolinite and clinoptilolite,desorption experiments were performed as well with tap water. The results indicated that in the case of Cs+ sorption on kaolinite the percentage desorption amounted to 40, but was smaller than 7 in the case of clinoptilolite. The desorption percentage of Sr2+ from clinoptilolite did not exceed 5, while it is amounted to 12 in kaolinite case, indicating a more stable fixation by clinoptilolite. The results showed that sorption of both Sr2+ and Cs+ on both minerals followed pseudo-second order kinetics, with the rate constants indicating faster sorption on kaolinite. The activation energies were 11.6 and 15.3 kj/mol for Cs+ sorption on kaolinite and clinoptilolite, respectively. Alternatively, the activation energy values for Sr2+ sorption on kaolinite and clinoptilolite were 8.5 and 17.3 kj/mol, respectively. Freundlich and D-R isotherm models were found to adequately describe the adsorption data of Sr2+ and Cs+ on both minerals.Cs+ sorption showed a spontaneous and exothermic behavior on both minerals with .H0 being .6.3 and .11.4 kj/mol for Cs+ uptake by kaolinite and clinoptilolite, respectively. On the other hand, Sr2+ sorption showed a spontaneous and endothermic behavior on both minerals with .H0 being 11.22 and 9.8 kj/mol for Sr2+ sorption on kaolinite and clinoptilolite, respectively. To check the effect of interlayer expansion on the uptake capacity of kaolinite, the clay was intercalated with DMSO, to overcome the tight H-bonding interconnecting the layers of the clay. Expanding the interlayer space of kaolinite from 0.71 nm to 1.12 nm using DMSO intercalation, lead to an increase in the sorption capacity of kaolinite, with the increase being more significant in Sr2+ case. Compared with the percentage sorption on natural kaolinite, the percentage sorption ofCs+ on DMSO-intercalated kaolinite for the initial concentrations of 100 and 500 mg/L of CsCl, increased, respectively, from 35 to 41, and from 27 to 33. On the other hand,the percentage sorption of Sr2+ on DMSO-intercalated kaolinite for the initial concentrations of 100 and 500 mg/L of Sr(NO3)2, increased from 17 to 58, and from 22 to 45,respectively. SEM/EDS characterization was carried out to investigate structural changes accompanying the sorption process. SEM analysis indicated that both minerals has a well-defined crystal structure. The EDS findings revealed some localization in the sorbed Sr2+ and Cs+ on the surfaces of both minerals and demonstrated the higher fixation ability of clinoptilolite.Master Thesis Aas, Xrpd, Sem/Eds, and Ftir Studies of the Effect of Calcite and Magnesite on the Uptake of Pb2+ and Zn2+ Ions by Natural Kaolinite and Clinoptilolite(Izmir Institute of Technology, 2005) Zünbül, Banu; Shahwan, Talal; Shahwan, TalalIn this study, the effect of magnesite and calcite on the uptake of lead and zinc ions by mixtures of these carbonates with kaolinite and clinoptilolite was investigated at various loadings and mixture compositions. The concentration of both ions in the liquid phase was in measured using AAS, while XRPD, SEM/EDS, and FTIR techniques were used in characterizing the solid samples. Thestudy included the determination of kinetics and sorption isotherms of lead and zinc on pure kaolinite and clinoptilolite. Moreover, the sorption behavior of lead and zincat different concentrations and pH conditions was investigated on mixtures of calcite and magnesite with kaolinite and clinoptilolite at carbonate mass percentage compositions of 5, 10, 25, 60 in addition to pure calcite and magnesite. The morphologies of theformed precipitates, the plausible structural change in the lattice of calcite, magnesite, kaolinite, and clinoptilolite originating from sorption of lead and zinc ions was examined. According to obtained results, the sorption affinity of kaolinite and clinoptilolite towards lead is larger than their affinity towards zinc. Within the operating experimental conditions, the sorption capacity increased with increasing the amountsof calcite, and magnesite. The overall order of retention of lead and zinc was observed as magnesite . calcite> clinoptilolite> kaolinite under neutral and alkaline pH conditions and high loadings. When the initialconcentration of zinc and lead ions is raised to saturation conditions, rapid overgrowth of cerussite and hydrozincite was observed. Increasing the initial pH to 10,0 causedenhancement in the dissolution of calcite and magnesite, leading to the enhancingthe precipitation of hydrozincite, and an increased formation of hydrocerussite instead ofcerussite. The uptake of Zn2+ and Pb2+ions by calcite and magnesite have lead to modifying the geometry of the carbonate groups, the thing reflected as variation in their vibrational bands.Master Thesis Chemical Behaviour of Clinoptilolite Rich Natural Zeolite in Aqueous Medium(Izmir Institute of Technology, 2005) Polatoğlu, İlker; Özkan, Seher FehimeIn this study the chemical behavior of natural zeolite from Gördes Türkey and its Na2CO3 treated form was investigated in acid (hydrochloric acid, lactic acid, acetic acid) and basic (sodium hydroxide) solutions. Synthetic gastric juice (hydrochloric acid and 0.4 % pepsin at pHi.2) was also prepared in order to examine the neutralizing capacity of zeolite for high acid concentration of stomach. The change in proton and hydroxyl concentration with time was studied by putting the different amount of zeolites into the various concentrations of acid and base solutions.It was found that natural zeolite tended to increase the pH of acidic solution while decreased the pH of basic solution depending on the concentration of proton or hydroxyl ions in solution and zeolite amount. The proton or hydroxide ions entered to the zeolite could not balance the cations released from zeolite structure. Therefore not only ion exchange, but also adsorption, cation hydrolysis, dissolution of Al and Si, complex formation and precipitation can be occurred. The neutralizing capacity of modified zeolite with sodium carbonate was higher than untreated ones. In the study conducted with synthetic gastric juice, 0.5 g modified zeolite did not significantly affect the pepsin activity of the medium and increased the pH to 2.9 which was between the normal ranges of stomach acid (2.9-3.1). In all aqueous studies conducted by using natural zeolite there was no change observed at the surface charge of the zeolite. According to characterizations performed it is understood that there was no significant change and the structure was stable. For these reason zeolite can be used as solid buffer in aqueous medium.Master Thesis Treatment of Domestic Wastewater With Natural Zeolites(Izmir Institute of Technology, 2004) Cansever, Beyhan; Ülkü, SemraIn this study, the use of Gördes natural zeolite for removing NH4+ ion from wastewater effluent and from NH4Cl solution was investigated under various conditions. The effect of the solid:solution ratio, initial concentration of the solution, presence of competing cation, particle size of the clinoptilolite sample on ammonium ion removal capacity were studied. Highest amount of ammonium removal per gram zeolite was found in the solution having 1% solid: solution ratio. The experimental results indicate that the NH4+ exchange capacity is not dependent on the particle size of the clinoptilolite sample. Increasing the initial concentration increases the NH4+ uptake capacity. NH4+ removal decreases with increasing the initial ammonium concentration. For instance, the higher NH4+ ion concentrations show the 30.5-55 % removal and lower NH4+ ion concentrations lead to 87-95 % removal for pure ammonium chloride solution. The presence of potassium ion had the most significant effect upon ammonium ion uptake, followed by calcium ion. Magnesium ion had the least effect.Equilibrium data obtained have been found to fit both Langmuir and Freundlich models. The Langmuir model provided excellent equilibrium data fitting (R2>0.995). From the plateau of the isotherms maximum exchange capacities were determined as 9.03, 8.76, 8.695 and 7.84 mg NH4+/gr for NH4+, NH4+-Mg+2, NH4+-Ca+2and NH4+-K+, respectively. As a consequence of this result, the ammonium capacity of Gördes clinoptilolite was approximately 0.51meq/gr for pure ammonium chloride solution. When comparing the removal of NH4+ ion from wastewater effluent and from NH4Cl, the percent removal and the uptake capacity were lower for wastewater than for NH4Cl for same solid: solution ratio and the same initial concentration. It is expected that in domestic wastewater, where the complexity of the system is high, several matter could influence the removal of specific target cations. The decreased ammonium removal for wastewater may be attributed to by the existence of several matters (suspended solid, organic matter) in the wastewater effluent samples, which reduce the ammonium exchange capacity.experimental results indicate a significant potential for the Gördes clinoptilolite rich mineral as an ion exchange material for wastewater treatment and water reuse application.Master Thesis Liquid Phase Hydrogenation of Citral on Zeolite Supported Monometallic (ni,pt) and Bimetallic (ni-Sn, Pt-Sn) Catalysts(Izmir Institute of Technology, 2005) Güleç, Hilal; Yılmaz, SelahattinIn this study the liquid phase citral hydrogenation reaction over zeolite supported monometallic and bimetallic Ni and Pt catalysts was studied. The zeolite support materials were Na-Y, Na-, Na-Mordenite, MCM-41, and Clinoptilolite. The catalysts were prepared by impregnation and co-impregnation techniques. Catalytic activity and selectivity tests were performed in a semi-batch reactor at 80°C temperature, 6 bar pressure and 600 rpm stirring speed with 0.25 g catalyst. The characterization studies showed that the structures of support materials were preserved during impregnation and co-impregnation. The Ni and Pt contents of the catalysts was around 8.5 % and 5 %, respectively while the Sn content changed between 0.46 and 4.10 %. The activity of the catalysts and product distribution were affected by type of active metal and type of support. The major product over monometallic and bimetallic catalysts was citronellal. The Ni/Na-Y catalyst gave the maximum yield of desired products, unsaturated alcohols and citronellal, (93 %) and citral conversion (>99 %) among the monometallic catalysts. The most selective monometallic Pt catalyst to desired products was Pt /MCM-41 with a yield of 40 %. Addition of Sn increased the unsaturated alcohol formation and decreased the acetal formation. The activity of the Ni catalyst was generally decreased while the activity of the Pt catalyst was improved. The amount of unsaturated alcohols increased with Sn/Sn+Ni ratio for bimetallic Ni catalysts. The highest yield of desired products was obtained with Ni/Na-Y (93 %) and with Ni-Sn/MCM (80 %) among monometallic and bimetallic catalysts.