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