Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Ion exchange in natural zeolite packed column(Izmir Institute of Technology, 2004) Can, Özge; Ülkü, SemraTurkish natural clinoptilolites were examined to evaluate their ion exchange performance for the removal of copper, nickel and cobalt ions by performing both batch and packed column experiments.Initial metal solutions were prepared using metal nitrate solutions at various concentrations.All of the experiments were carried out at 29oC.Before performing the ion exchange experiments zeolites were characterized and their clinoptilolite contents were determined quantitatively as 80 and 64 % for zeolites named as CP1 and CP2, respectively.The copper exchange capacities of CP1 and CP2 were determined from equilibrium studies as 10.01 mg (0.32 meq) Cu2+ / g CP1 and 8.33 mg (0.262 meq) Cu2+ / g CP2. Ion exchange capacity of CP2 zeolite was determined as 6.64 mg (0.226 meq) Ni2+ / g and 4.55 mg (0.154 meq) Co2+ / g.The equilibrium behaviour of the system was best described by Langmuir model.Experiments were designed to investigate the optimum parameters and significance of the interactions between these parameters.In column studies, the parameters such as packing height, inlet metal concentration and flow rate were investigated.The concentration of the metals in the sample solutions which were taken from the exit of the ion exchange column at specific time intervals were analyzed by using Optical Emission Spectrometry (ICP-OES).Afterwards, by making use of the data obtained from ICP-OES, breakthrough curves were constructed.By the help of these curves, breakthrough capacity and ion exchange capacity of natural zeolites were calculated.The ion exchange capacity of CP2 zeolite was calculated as 8.04 mg Cu2+/g CP2, which was consistent with the capacity calculated from batch experiments, 8.33 mg Cu2+/g CP2.Also, breakthrough points were determined. Furthermore, solid phase was also analysed for determining its crystal structure and chemical composition using Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray (EDX) devices (Philips XL 30S FEG).In addition to these, natural zeolite particles which have been ion exchanged throughout this process were regenerated using 0.2M and 1.7M of NaCl solutions.According to regeneration studies, it was determined that 94 and 95% of copper were recovered within the first 100 minutes for both experiments.After the experiments were performed, model equations were applied to the system in order to be able to investigate the dynamic behavior of the system.As a result of this simulation, breakthrough was well predicted.Master Thesis A Chromatographicstudy of Carbon Monoxide Adsorption in Clinoptilolite(Izmir Institute of Technology, 2001) Narin, Güler; Ülkü, SemraAdsorption equilibrium and kinetic parameters for CO/clinoptilolite adsorbate/adsorbent pair were determined by perturbation gas chromatography. Chromatographic experiments were performed at temperatures in the 60-120°C range and at carrier gas flow rates in the range of 10.31-24.36 em/sec. The chromatographic response peaks were obtained by concentration pulse method. A packed column of 10 em length and 0.46 em inlet diameter which was packed with clinoptilolite particles with narrow size distribution (500-850 §) around mean diameter of301.9 § was used. The clinopti10lite particles were excavated from Gordes, Western Anatolia. The moments of the response peaks were calculated by integration of experimental chromatographic data and matched to the .model parameters in order to determine the equilibrium constants and diffusion coefficients. The dynamic model (Haynes and Sarma, 1973) was applied to describe the adsorption and diffusion processes in the packed column. This model includes axial dispersion, external mass transfer resistance, micropore and mesopore diffusion resistances. The equilibrium constants (Henry's law constants, K) were calculated in the range of 40 - 952 and were found to be in good agreement with the results in the literature. These constants were found to decrease with increasing temperature. The heats of adsorption were obtained in the range of 54.15 - 57.14 kl/mol from the slope of van't Hoff plots and compared with those in the literature. The heats of adsorption were found to be lower than those reported in the literature obtained for the same adsorbate/adsorbent pair. The higher heats of adsorption were explained by the smaller pore size, higher cation content of the clinoptilolite and more accessibility of the cations in the clinoptilolite framework by CO molecules. Heats of adsorption remained almost constant over the carrier gas velocity range studied. The contributions of axial dispersion and other mass transfer resistances Indiffusion of CO in clinoptilolite were also determined. The total dispersion exhibited slight change (average 0.035 see) with temperature implying that the micropore diffusional resistance was not dominant for diffusion of CO in clinoptilolite under the experimental conditions studied. The axial dispersion coefficient was determined in the range of 1.149.88 cm2/sec and the total mass transfer resistances were found between 0,02-0.06 sec. The results showed that the mesopore diffusion resistance was the controlling mechanism in CO diffusion in clinoptilolite. Mesopore diffusion coefficient was estimated as 2.98xlO-3 cm2/sec. This value was in good agreement with the theoretically determined value.Master Thesis Removal of Heavy Metals From Wastewaters by Use of Natural Zeolites(Izmir Institute of Technology, 2001) Türkmen, Müşerref; Ülkü, SemraIn the present study, clinoptilolite rich local natural zeolite was proposed as an ion-exchanger for the removal of heavy metals (Pb2+, Cu2+, Zn2+) from wastewaters.Natural zeolite samples were exposed to a simple pretreatment process which included washing and drying to remove impurities and dust.Thermal and adsorption related properties of washed and original zeolite samples were determined by TGA and N2 adsorption analyses. In TGA analyses, average water content for washed and original samples were found as 9.44 and 10.13 % respectively. In N2 adsorption studies, both washed and original samples showed the characteristic Type IIb isotherm. BET surface areas of the samples were calculated as 39.73 and 47.72 m2/g for washed and original samples respectively.Pretreatment process was found to improve the adsorption capacity of clinoptilolite due to the removal of impurities and dust.In ion-exchange studies, efficiency of natural zeolite in removal of heavy metals from the solutions was investigated based on some physical and chemical variables. For this purpose, particle size and the amount of zeolite in the solution, contact time of the metal containing solution with zeolite were selected as physical variables and pH, metal concentration of the solution, and the presence of other ions were selected as chemical variables. The chemical analyses of all exchange solutions were performed by using ICP-AES. Removal % of the metal ions from the solutions were obtained. Based on the experimental results, zeolite exhibited a significant affinity to Pb2+, followed by Cu2+ and Zn2+ even in the presence of competing cations.To test the applicability of natural zeolite for the treatment of Acid Mine Drainage (AMD), zeolite samples were allowed to contact with simulated AMD solutions.Consequently, natural zeolite was found to be an efficient ion exchanger for removing lead, copper and zinc ions from aqueous solutions.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.