Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 4Citation - Scopus: 5Breakthrough Curve Analysis of Phosphorylated Hazelnut Shell Waste in Column Operation for Continuous Harvesting of Lithium From Water(Elsevier, 2024) Recepoğlu, Yaşar Kemal; Arar, Ozguer; Yuksel, AsliIn batch-scale operations, biosorption employing phosphorylated hazelnut shell waste (FHS) revealed excellent lithium removal and recovery efficiency. Scaling up and implementing packed bed column systems necessitates further design and performance optimization. Lithium biosorption via FHS was investigated utilizing a continuous-flow packed-bed column operated under various flow rates and bed heights to remove Li to ultra-low levels and recover it. The Li biosorption capacity of the FHS column was unaffected by the bed height, however, when the flow rate was increased, the capacity of the FHS column decreased. The breakthrough time, exhaustion time, and uptake capacity of the column bed increased with increasing column bed height, whereas they decreased with increasing influent flow rate. At flow rates of 0.25, 0.5, and 1.0 mL/min, bed volumes (BVs, mL solution/mL biosorbent) at the breakthrough point were found to be 477, 369, and 347, respectively, with the required BVs for total saturation point of 941, 911, and 829, while the total capacity was calculated as 22.29, 20.07, and 17.69 mg Li/g sorbent. In the 1.0, 1.5, and 2.0 cm height columns filled with FHS, the breakthrough times were 282, 366, and 433 min, respectively, whereas the periods required for saturation were 781, 897, and 1033 min. The three conventional breakthrough models of the Thomas, Yoon-Nelson, and Modified Dose-Response (MDR) were used to properly estimate the whole breakthrough behavior of the FHS column and the characteristic model parameters. Li's extremely favorable separation utilizing FHS was evidenced by the steep S-shape of the breakthrough curves for both parameters flow rate and bed height. The reusability of FHS was demonstrated by operating the packed bed column in multi-cycle mode, with no appreciable loss in column performance.Article Citation - WoS: 10Citation - Scopus: 12Novel Hybrid Adsorption-Electrodialysis (aded) System for Removal of Boron From Geothermal Brine(American Chemical Society, 2022) Altınbaş, Bekir Fırat; Orak, Ceren; Ökten, Hatice Eser; Yüksel, AslıA novel hybrid adsorption-electrodialysis (AdED) system to remove environmentally harmful boron from geothermal brine was designed and effective operating parameters such as pH, voltage, and flow rate were studied. A cellulose-based adsorbent was synthesized from glycidyl methacrylate (GMA) grafted cellulose and modified with a boron selective n-methyl-d-glucamine (NMDG) group and characterized with SEM-EDX, FT-IR, and TGA analyses. Batch adsorption studies revealed that cellulose-based adsorbent showed a remarkable boron removal capacity (19.29 mg/g), a wide stable operating pH range (2-10), and an adsorption process that followed the Freundlich isotherm (R2= 0.95) and pseudo-second-order kinetics (R2= 0.99). In the hybrid AdED system, the optimum operating parameters for boron removal were found to be a pH of 10, a voltage of 10 V, a flow rate of 100 mL/min, and an adsorbent dosage of 4 g/L. The presence of the adsorbent in the hybrid system increased boron removal from real geothermal brine (containing 199 ppm boron) from 7.2% to 73.3%. The results indicate that the designed AdED system performs better than bare electrodialysis for boron removal from ion-rich real geothermal brine while utilizing environmentally friendly cellulose-based adsorbent.Article Citation - WoS: 13Citation - Scopus: 11Valorization of Olive Tree Pruning Waste for Potential Utilization in Lithium Recovery From Aqueous Solutions(Springer, 2022) Nampeera, Jackline; Recepoğlu, Yaşar Kemal; Yüksel, AslıOlive tree pruning waste, mainly composed of olive branches, was converted into a value-added and sustainable product capable of lithium as a biosorbent through alkali treatment and phosphorylation reaction. Characterization studies were performed by SEM–EDX, XPS, FTIR, and TGA. Factors affecting biosorption mechanism, i.e., sorbent dosage, pH, initial Li+ concentration and temperature, and competitive ions’ presence, were investigated the synthesized functionalized olive branches (FOB). A commercial lithium selective resin, Lewatit TP 260, was also compared with FOB in batch and column studies. The Freundlich model fits adsorption isotherms better than the Langmuir model, with a maximum adsorption capacity of 6.7 mg/g at 30 °C and pH 7–8. Kinetic studies proved fast kinetics and equilibrium were attained in 6 min, while thermodynamic studies showed an exothermic (Δ Ho= - 17.52 kJ/ mol) , spontaneous reaction Δ Go< 0 at all temperatures), and increased randomness Δ So= + 24.27 J/ mol. K) at the interaction interface. Column studies revealed that although Lewatit TP 260 resin showed higher sorption capacity, its desorption efficiency (50.42%) was lower than that of FOB (99.9%), and the degree of column utilization of FOB (56.81%) was better than Lewatit TP 260 resin’s (16.0%). The findings were encouraging in the successful synthesis of a promising biosorbent from an abundant waste in Turkey for use in sustainable lithium recovery from aqueous sources. Graphical abstract: [Figure not available: see fulltext.]Article Citation - WoS: 1Citation - Scopus: 1Selective Catalytic Hydrogenation of Cellulose Into Sorbitol With Ru-Based Catalysts(TÜBİTAK, 2022) Orak, Ceren; Sapmaz, Aycan; Yüksel, AslıSorbitol is one of the platform chemicals and can be produced from various renewable and sustainable sources via different processes. Hydrothermal liquefaction is an effective and promising approach to produce sorbitol, since the subcritical reaction media and appropriate catalysts provide a selective production of platform chemicals. In this study, sorbitol was produced from different renewable sources (cellulose and glucose) in the presence of Ru-based catalysts (Ru/SiO2, Ru/AC, Ru/SBA-15, and Ru/SBA-15-SO3) under subcritical conditions. The highest cellulose conversion was achieved as 90% in the presence of Ru/SBA-15-SO3 for 1 h of reaction duration. The highest sorbitol yield (%) by hydrothermal liquefaction of cellulose was obtained as 6.2% by using Ru/AC for 1 h of reaction duration. A total of 99.9% of glucose conversion was achieved in the presence of all catalysts. The highest sorbitol yield (%) by hydrothermal liquefaction of glucose was found as 3.8% for 1 h of reaction duration. Owing to the results of GC-MS analysis, the intermediate products were identified, and, thus, a reaction pathway was proposed.Article Citation - WoS: 13Citation - Scopus: 12Comparison of Photocatalytic Performances of Solar-Driven Hybrid Catalysts for Hydrogen Energy Evolution From 1,8–diazabicyclo[5.4.0]undec-7 (dbu) Solution(Elsevier, 2022) Orak, Ceren; Yüksel, AslıHydrogen is evolved from 1,8–Diazabicyclo [5.4.0]undec-7-ene (DBU) model solution which is a nitrogen-containing heterocyclic organic compound using different solar-driven hybrid photocatalysts. A characterization study is performed and the results of PL analysis show that the most promising solar-driven hybrid catalyst is graphene supported LaFeO3. Then, an experimental design matrix is built using the Box Behnken model to main and interaction effects of reaction parameters (pH, catalyst loading, and [H2O2]0). Based on the experimental results relatively higher hydrogen amounts are achieved using GLFO and this finding is supported by PL analysis. The highest hydrogen amount and DBU removal are determined as 3058.31 μmol/gcat and 90.3%, respectively. Statistical analysis shows that the square of catalyst loading is the only effective parameter over the produced hydrogen amount from the DBU model solution using GLFO and the R2 of model is 92.47%. Thus, hydrogen production and wastewater treatment could be achieved via photocatalytic oxidation as concomitant.Article Citation - WoS: 14Citation - Scopus: 12Photocatalytic Hydrogen Energy Evolution From Sugar Beet Wastewater(Wiley-VCH Verlag, 2021) Orak, Ceren; Yüksel, AslıHydrogen is a clean, environmentally friendly, storable, and sustainable green energy source as well as a potential fuel. It could be produced from various biomass, wastewater, or other sources by different processes. In this study, hydrogen was evolved from sucrose model solution and real sugar beet wastewater by photocatalytic oxidation using a perovskite catalyst under solar light irradiation. In this context, firstly, the graphene supported LaFeO3 (GLFO) was synthesized and then, a characterization study shows that GLFO is successfully synthesized. To optimize the reaction parameters (pH, catalyst loading, and initial hydrogen peroxide concentration), an experimental matrix was created using the Box Behnken model. Whereas the highest hydrogen evolution from sucrose model solution was observed as 3520 μmol/gcat, the highest hydrogen evolution from sugar beet wastewater was obtained as 7035 μmol/gcat. The highest TOC removal (99.73 %) from sugar beet wastewater was also achieved at the same reaction conditions.Conference Object Acid-Catalyzed Degradation of Biomass With Hydrothermal Electrolysis for the Production of Value-Added Chemicals(American Chemical Society, 2014) Yüksel, Aslı; Yüksel Özşen, Aslı[No abstract available]Article Citation - WoS: 31Citation - Scopus: 38Liquefaction of Waste Hazelnut Shell by Using Sub- and Supercritical Solvents as a Reaction Medium(Elsevier, 2019) Demirkaya, Emre; Dal, Orkan; Yüksel, AslıDirect 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, up to our best knowledge, in this study, hazelnut shell decomposition by using ethanol, acetone and their mixtures at sub/supercritical conditions was studied for the first time in literature. Experiments were carried out between 220-300 degrees C, at three different reaction times (30, 60 and 90 min) for five different solvent ratios. Highest solid conversion achieved at 300 degrees C by using pure ethanol was 64.2%, whereas highest bio-oil yield was found as 44.2% at 300 degrees C with 50/50 (EtOH/Ac: v/v). Ethanol and acetone showed different characteristics during the reactions and their effects on the conversion and bio-oil yield were discussed. Statistical analysis showed that time, temperature, ratio and synergy between temperature-time were affecting parameters for the conversion and bio-oil yield. (C) 2019 Elsevier B.V. All rights reserved.Article Citation - WoS: 4Citation - Scopus: 4Novel Hybrid Process for the Conversion of Microcrystalline Cellulose To Value-Added Chemicals: Part 3: Detailed Reaction Pathway(Springer Verlag, 2019) Akın, Okan; Yüksel, AslıIn this study, a novel method of hydrothermal electrolysis of microcrystalline cellulose (MCC) under sub-critical water conditions (200 degrees C) was investigated by applying direct current at constant voltage with the presence of acid catalyst of 5mMH(2)SO(4). Direct current at constant voltage of 2.5V, 4.0V and 8.0V was applied between cylindrical anode (titanium) and cathode (reactor wall). Hydrothermal electrolysis reactions were carried out in a batch reactor (450mL-T316) for the reaction time of 240min. Decomposition products of MCC were analyzed by GC-MS and the decomposition pathway of cellulose under applied voltage was postulated. Levoglucosan and levoglucosenone formations were detected as the first hydrolysis products of MCC and further hydrolysis yielded to formation of glucose and fructose. The major decomposition products of cellulose were detected as levulinic acid (LA), 5-HMF and furfural. Further reactions of LA such as electrochemical decarboxylation, dehydration, hydrogenation, resulted in the formation of 2-butanone, 2-butanone-3-hydroxy, gamma-valerolactone, respectively. Most dramatic results on the product distribution were obtained at applied 2.5V voltage in which LVA and 5-HMF were selectively produced. [GRAPHICS] .Conference Object Electrolysis of Alcohols in High Temperature-High Pressure Water(Materials Research Society, 2013) Yüksel, Aslı; Sasaki, Mitsuru; Goto, MotonobuThe design of clean, efficient and environmentally friendly routes that reduce the waste production and fuel emissions of pollutants into the atmosphere, produce clean, affordable, and renewable energy sources to lessen energy consumption and toxicity on the environment, has become a central issue of chemical research both in industry and academia. One of the approaches being used in green chemistry practices is to use water as a solvent and reaction medium where possible. Much of this work deals with liquid water at temperatures exceeding the normal boiling point which is denoted as sub-critical water. Electrochemical reaction, usually operated at atmospheric condition in water, is generally slow, although it has advantages over chemical reaction such as suppression of side reaction by tuning operating conditions. Since sub-critical water (7 MPa and 250 °C) has remarkable properties such as high ion product and low dielectric constant, it could be a suitable reaction media. We have been studying electrolysis of organic compounds in sub-critical water as waste treatment and molecular degradation technologies. Electrolysis in sub-critical water could degrade harmful and thermally stable organic compounds into innocuous compounds such as hydrogen and water. In this research, we focused on the investigation of the electrochemical reactions of alcohols in sub-critical water to evaluate possibility for the selective production of hydrogen and value-added chemicals. Electrochemical reactions were carried out in sub-critical water using a specially designed autoclave made of SS 316 with a volume of 500 mL. For comparison, thermal degradation experiments of alcohols were also conducted without any direct current loading at identical conditions. Here we employed glycerol and 1-butanol as model compounds of alcohols. As a result of 1-butanol experiments, butanal and butyric acid were produced via partial oxidation at 250 °C and by applying 1-3 A of direct current while no oxidation products were observed at the hydrothermal degradation run. As a gaseous product, hydrogen gas was generated according to the electrochemical reaction mechanism. In the case of glycerol experiments, the main gaseous product was hydrogen gas, whereas glycolaldehyde, lactic acid, and formic acid were generated as the main liquid products at 280 °C. Results indicated that greater than 92% of the glycerol could be decomposed under optimum conditions by hydrothermal electrolysis technique. This presented research will help to degrade stable organic materials in an environmentally friendly way and without need for secondary treatment processes. It will also address the need for novel more efficient techniques for the degradation of stable organic compounds in aqueous conditions and it will advance the use of water as a reaction medium in an efficient way without any organic solvent.