Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Valorization of Biomass for Fuel and Chemicals Production(01. Izmir Institute of Technology, 2023) Yüksel Özşen, Aslı; Yüksel Özşen, Aslı; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyRapidly increasing global energy demand resulting from the growing population and worldwide development increased consumption of limited fossil fuel usage that causes severe environmental deterioration by CO2 emission have sparked interest in finding green, renewable, and sustainable alternative sources for energy. Bio-oil, derived by several biomass via liquefaction, is a promising candidate to replace fossil fuels. Turkey is a country, 27% of which is covered with forests (mostly oak trees). Therefore, it has great potential for cheap lignocellulosic feedstock forest residues from industrial applications and harvesting. In the present study, the thermal liquefaction of oak wood particles (OWP) was performed using various solvents besides water, such as ethanol, 1-butanol, and 1,4-dioxane. The experiments were carried out in a batch reactor for 1 and 2 h residence time at different temperatures (210oC, 240oC, and 270oC). Bio-oil samples obtained at best reaction temperature, 270oC, optimum residence time, 1 h, were analyzed with TGA, CHNS elemental analyzer, FTIR, and GC-MS. Based on energy recovery calculations, the enhancement of pristine OWP's energy efficiency depends on bio-oil yield, and quality was confirmed for all solvent types. 1,4-dioxane showed the best performance in yielding the maximum bio-oil with 51.8%. The higher heating values of the bio-oils ranged from 22.1 to 35 MJ/kg. Phenolic groups were the predominant components of bio-oil produced from OWP, while intensity of alcohols, ketones, and acids varied based on using solvents.Master Thesis Synthesis of Natural Adsorbents From Lignocellulosic Biomass for the Recovery of Boron From Water Resources(01. Izmir Institute of Technology, 2023) Yüksel Özşen, Aslı; Yüksel Özşen, Aslı; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThis work investigated the valorization of olive tree pruning waste as a biosorbent for the removal of environmentally hazardous boron from aqueous solution using batch adsorption. For this purpose, a novel, waste-based, boron-selective biosorbent from pristine cellulose and olive tree pruning waste (N-OPW) was synthesized. After confirming the proposed synthesis route with pristine cellulose, an alkali pretreatment, followed by glycidyl-methacrylate (GMA) grafting and providing boron selectivity with n-methyl-d-glucamine (NMDG) steps were applied to the biomass, respectively. N-OPW was characterized using SEM, TGA and FT-IR analyses. N-OPW showed excellent boron biosorption capacity (21.80 mg/g) in an operation pH range between 2-12. The equilibrium was attained in two hours and the Freundlich isotherm (R2=0.997) and pseudo-second-order kinetics (R2=0.99) provided the strongest match to experimental data. According to thermodynamic studies, boron adsorption was exothermic (ΔH°= - 34.14 kJ/mol). The reusability tests with real geothermal water showed that adsorbent had no significant decrease in boron removal capacity while desorbing >99% of the boron adsorbed for three cycles of adsorption/desorption. Results indicated that a promising, reusable, and boron-selective biosorbent was successfully synthesized while utilizing olive pruning waste.Master Thesis Photocatalytic Degradation of Rhodamine B Using Ag/Agcl@go(01. Izmir Institute of Technology, 2023) Yüksel Özşen, Aslı; Yüksel Özşen, Aslı; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyWater is an essential source for earth. According to the United Nation’s report, every day 1800 children dies because of contaminated water. Dyes are one of the most common water pollutants. They are using in many areas like cosmetic, textile, pharmaceutical etc. Every year nearly 140,000 tons of dye releasing to the environment. Therefore, removal of dyes from water is an essential topic. There are many ways to remove dyes from water. However, studies showed that traditional methods are ineffective to removing pollutants from water. On the other hand, photocatalysis is a promising technology. In this study, Ag/AgCl and Ag/AgCl@GO photocatalysts were synthesized and their removal performances on Rhodamine B dye were investigated. In addition, the parameters affecting the removal performance were also studied. Characterization tests such as synthesized photocatalysts, XRD, BET, UV-Vis Analysis, TGA, SEM, TEM was carried out. According to the XRD results, the peak regions of the synthesized photocatalysts were similar to other studies in the literature. The synthesized photocatalysts were first studied under 3 different pH values (pH:3, pH:8, pH:11) using 10 ppm rhodamine b dye and 30 mg catalyst under UV light. According to the results, for both photocatalysts, their natural pH, namely pH:8, showed the best performance. Afterwards, experiments were carried out with different photocatalyst weights and it was observed that the removal performance did not change after 40 mg. Finally, different dye amounts were studied and it was observed that as the dye amount increased, its removal decreased. It has been observed that the addition of graphene oxide significantly improves the performance of the catalyst.Master Thesis Adsorbent Synthesis for the Recovery of Lithium Water Resources(01. Izmir Institute of Technology, 2022) Yüksel Özşen, Aslı; Yüksel Özşen, Aslı; Yüksel Özşen, Aslı; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyLithium is a crucial mineral for the 21st century due to its utilization in a wide range of industries. Lithium demand will increase because of car battery developments and the necessity for power storage. Investigating alternative strategies for resource recovery is the only way to fulfill this unexpected rise properly and sustainably in demand. Adsorption has been discovered to have some technological advantages over other methods. It is considerably less expensive, lacks the chemical resistance present in membranes, lacks the significant electrical demand of electrochemical approaches, as well as the restricted selectivity and challenges in integration into commercial processes. Lithium manganese oxides, also known as lithium ion-sieves, are adsorbents for lithium extraction that have remarkably high selectivity, high adsorption capacity, minimal toxicity, good chemical stability and cheap cost. They are one of the most promising inorganic adsorbents. This research emphasized on the recovery of lithium from water resources through the use of lithium manganese oxide, which were synthesized in laboratory. They were transformed into spherical beads by adding chitosan, followed by crosslinking these beads with epichlorohydrin to increase their adsorption yield, stability, and reusability. Characterization techniques such as SEM, XRD and BET were applied on the adsorbents. Results shows that the adsorbents distributed uniformly, the adsorbent powder was mesoporous, and from the adsorption studies it was found that the adsorbent worked much better in alkaline conditions such as pH 12, optimum adsorbent dosage estimated as 4 g/L and the equilibrium time measured as 10 hours. From the desorption study approximately 95% of Li desorbed for the first cycle, after the second cycle the adsorbent efficiency started to decrease.Master Thesis Functionalized Cellulose-Based Adsorbent for Lithium Recoveryfrom Aqueous Solutions(01. Izmir Institute of Technology, 2021) Nampeera, Jackline; Yüksel Özşen, Aslı; Yüksel Özşen, Aslı; 01. Izmir Institute of Technology; 03.02. Department of Chemical Engineering; 03. Faculty of EngineeringThis study focused on generation of low-cost yet highly effective lithium selective bio-sorbent from olive pruning waste mainly olive branches. Olive branches were treated with NaOH that eliminated non-cellulosic materials and activated hydroxyl groups that inhibit the formation of active sites. Olive branches were then functionalized through homogeneous phosphorylation at 150 ⁰C. POB, NOB, and FOB samples were subjected to SEM, XRD, FTIR, BET, XPS, and TGA to observe the changes in their structure and properties. Factors affecting lithium adsorption were investigated on the synthesized FOB in a batch system and analyzed by ICP-OES. Adsorption isotherms are well fitted to the Freundlich isotherm model than the Langmuir isotherm model which exhibited a maximum adsorption capacity of 6.7 mg/g at 30 ⁰C. Kinetic studies exhibited fast kinetics and equilibrium was attained in 6 minutes while thermodynamic studies showed an exothermic, spontaneous reaction and increased randomness at the interaction interface. Regeneration studies proved the sustainability of FOB with Li+ desorption efficiency of 99.6% in 1.0 M HCl. The synthesized FOB displayed a better degree of column utilization and elution efficiency; 56.8% and 95.8% than Lewatit TP 260; 16.0% and 50.4% respectively in the adsorption column studies performed at room temperature. However, it exhibited a poor breakthrough capacity of 2.1 mg Li/ml sorbent than Lewatit TP 260 with 1.33 mg Li/ml sorbent. Based on all experimental results, the novel functionalized olive branches (FOB) proved a potential lithium selective bio-sorbent and can be applied in the recovery of lithium from its aqueous sources.Master Thesis Extraction of Oleuropein From Olive Leaves(01. Izmir Institute of Technology, 2020) Yüksel Özşen, Aslı; Yüksel Özşen, Aslı; Yüksel Özşen, Aslı; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe aim of this study is to obtain oleuropein, which is the main phenolic compound content of olive leaf by soxhlet extraction. Oleuropein has been known in the health field for a long time and is found in high rates in our country. In this context, the effect of various solvent types (ethanol, methanol, acetonitrile and water), extraction time (4 cycles, 4 hours, 8 hours), particle size (250-500 µm and 900-2000 µm) and the pre-treatment applied to the olive leaf on the yield of oleuropein was investigated. The amount of oleuropein in the liquid product was determined using a High Performance Liquid Chromatogram (HPLC). When the grain size of the raw material to be used in extraction was reduced, higher oleuropein was obtained. The use of solvents in an aqueous form resulted in a higher amount of oleuropein compared to pure solvents. Increasing the extraction time caused a significant increase in the amount of oleuropein. On the contrary, it was observed that the pretreatment applied to olive leaves caused a decrease in the yield of oleuropein. As a result of these findings, the highest oleuropein amount and extraction efficiency were obtained after 8 hours of extraction period by using olive leaf with 250-500 μm grain size and 80% methanol solution as the solvent. The highest oleuropein amount was found to be 13.35 oleuropein mg/g dry leaves and the highest extraction efficiency under these conditions was found to be 36 %.Master Thesis Production of Bio-Oil From Haelnut Shell Waste by Using Supercritical Ethanol, Acetone and Their Mixtur(Izmir Institute of Technology, 2018) Dal, Orkan; Yüksel Özşen, Aslı; Yüksel Özşen, Aslı; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe goal of this study was to investigate effect of reaction temperature, reaction time and solvent ratio (ethanol/acetone v/v%) on bio-oil yield, solid conversion and product distribution. Direct thermochemical biomass degradation to obtain bio-oil by using organic solvents is not a new process type, and it has some advantages over hydrothermal liquefaction technique. However, in literature, to our best knowledge, there is no study about hazelnut shell decomposition by using ethanol, acetone and their mixtures at sub/supercritical conditions. In this study, experiments were carried out between 220-300 °C, at three different temperatures (30, 60 & 90 min) for five different solvent ratios. Highest solid conversion achieved at 300 °C by using pure ethanol was 64.2%, whereas highest bio-oil yield was found as 44.2% at 300 °C with 50/50 (EtOH/Ac: v/v). Ethanol and acetone showed different characteristics during the experiments and their effect on the conversion and bio-oil yield were discussed. Statistical analysis showed that time, temperature, ratio and temperature-time are affecting parameters for the conversion and bio oil yield while time-ratio and temperature-ratio are not. According to GC-MS results, product distribution changed with respect to solvent type and ratio.Master Thesis Extraction of Phenolic Compounds From Hazelnut Shell Waste(Izmir Institute of Technology, 2018) Şengün, Duygu; Yüksel Özşen, Aslı; Yüksel Özşen, Aslı; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe main objective of this study is to obtain phenolic compounds from hazelnut shell waste by extraction and to add value to hazelnut shell wastes. Soxhlet extraction, ultrasonic extraction and combined extraction (soxhlet followed by ultrasonic extraction) methods were used for the extraction of hazelnut shell to obtain phenolic and antioxidant compounds. The effect of extracting solvent (ethanol, methanol, n-hexane, acetone and chloroform), extraction time (8h, 2 cycle and 3 cycle) (1 cycle = 20 min for hexane, 25 min for chloroform, 40 min for ethanol, 45 min for methanol and 35 min for acetone), solid-liquid ratio (4, 8 and 12 g / 250 ml) and size of hazelnut shell (1 mm and 2 mm) were investigated on the phenolic content and antioxidant capacity. Gas Chromatography equipped with a Mass Spectrometry (GC-MS) was used for the analysis of liquid products obtained from the extraction of hazelnut shell. Palmitic acid and oleic acid variations were detected at high ratios. The combined extraction method, which was composed of soxhlet and ultrasonic extractions, resulted in a significant increase in the yield of extraction. Also, higher yield was obtained from methanol and ethanol extraction because of the higher polarity of the solvents. On the other hand, it was observed that there was no significant effect of the extraction time on the extraction yield. The highest phenolic content was 0.166 mg gallic acid equivalent/ml and this value was obtained with methanol by combined extraction using 4 g hazelnut shell and 250 ml solvent.Master Thesis Mineralization of Olive Mill Wastewater Under Hydrothermal Conditions(Izmir Institute of Technology, 2017) Ersanlı, Çağlar; Yüksel Özşen, Aslı; Yüksel Özşen, Aslı; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe purpose of this study is to reduce the total organic carbon (TOC) and chemical oxygen demand (COD) concentrations, color, the concentration of total phenolic compounds of olive mill wastewater (OMW) by hydrothermal degradation in subcritical water medium with and without using hydrogen peroxide (H2O2). In addition to this, investigation of effect of reaction temperature, reaction time and H2O2 concentration on the reduction of TOC, COD, color and total phenolic content; and controlling the generation of secondary pollutants during the reactions are other objectives of this study. Hydrothermal degradation reactions were performed at 150-250 ºC of reaction temperature, 30-120 minutes of reaction duration with 0-100 mM H2O2. Experimental design and statistical analysis (ANOVA) were carried out by Minitab. The main product of partial mineralization of OMW was acetic acid. Increase in the reaction temperature and time resulted in increasing TOC reduction rates significantly. On the other hand, presence of H2O2 did not affect the removal efficiency of TOC concentration significantly because of competition of hydroxyl free radicals by H2O2 and target molecule (OMW). The best yield (31.65%) of TOC reduction was achieved with a reaction at 250 ºC, 120 min and without using H2O2.Master Thesis Conversion of Hazelnut Shell Into Value-Added Chemicals by Using Sub-Critical Water as a Reaction Medium(Izmir Institute of Technology, 2016) Gözaydın, Gökalp; Yüksel Özşen, Aslı; Yüksel Özşen, Aslı; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe objective of this study is to clarify the effect of reaction temperature, reaction time, acid concentration and acid type on the hydrothermal conversion of waste hazelnut shell into value-added chemicals under hot compressed water with high temperature/high pressure autoclave. The other aim is to gaining of added value and new utilization field to waste hazelnut shell. This is the first study about the degradation of waste hazelnut shell in order to produce levulinic acid under subcritical water in literature. Reactions were performed at 150-280 °C of reaction temperature, 15-120 min of reaction time with different acid (H2SO4 and H3PO4) concentrations that was varied from 0 to 125 mM. The liquid product distribution was evaluated with High Performance Liquid Chromatography (HPLC) and Gas Chromatography-Mass Spectrometry (GC-MS) and gas products were identified by Gas Chromatography with a Thermal Conductivity Detector (GC-TCD). While levulinic acid, acetic acid and furfural were identified as a major liquid compounds, the main gaseous products were carbon dioxide and carbon monoxide. Increasing reaction temperature and reaction time improved the conversion of hazelnut shell up to 65.40% at 280 °C and 120 min in the presence of 50 mM H2SO4 and 13.05% of levulinic acid yield was obtained under the similar reaction conditions. Addition of dilute H2SO4 and H3PO4 in the reaction medium enhanced different product formation. H2SO4 treatment promoted the production of levulinic acid whereas addition of H3PO4 increased the formation of furfural. Furthermore, total phenolic content, antioxidant capacity and possible reaction pathways of hydrothermal conversion of waste hazelnut shell was evaluated.