Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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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 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.