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: 25Citation - Scopus: 26Phosphorylated Hazelnut Shell Waste for Sustainable Lithium Recovery Application as Biosorbent(Springer, 2021) Recepoğlu, Yaşar Kemal; Yüksel, AslıHazelnut shell waste was phosphorylated to develop a novel biosorbent based on natural renewable resource for the recovery of lithium from aqueous solution. For the synthesized biosorbent, the surface morphology and mapping by SEM-EDS, chemical properties by FTIR, elemental analysis by XPS, specific surface area by BET, crystallinity by XRD and thermal properties by TGA were elucidated elaborately. The influence of biosorbent dosage, initial concentration, temperature, contact time, pH and coexisting ions were investigated. The equilibrium sorption capacity reached 6.03 mg/g under optimal conditions (i.e., biosorbent dosage of 12.0 g/L, initial Li concentration of 100 mg/L, pH value of 5.8, sorption temperature of 25 degrees C, and sorption time of 6 min). According to the sorption behavior of the phosphorylated hazelnut shell waste the Freundlich model proved to be more suitable than the Langmuir model indicating maximum sorption capacity as 7.71 mg/g at 25 degrees C. Thermodynamic parameters obtained by different isokinetic temperatures disclosed that the ion exchange reaction was feasible, spontaneous, and exothermic where the interaction between biosorbent surface and solvent plays an important role. A preliminary test on the Li recovery from geothermal water was also performed to check its applicability in a real brine. Desorption studies at 25 degrees C revealed that relatively higher desorption efficiency and capacity were achieved at 97.4% and 5.93 mg/g, respectively with a 1.0 M H2SO4 among other regenerants (i.e., HCl and NaCl). Concentrations of Li and the other cations were determined via ICP-OES. Due to such outstanding features, the novel phosphorylated hazelnut shell waste had great potential for lithium recovery from aqueous solution by being added value as a waste and recovering a strategic element of modern life simultaneously. [GRAPHICS] .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: 11Citation - Scopus: 12Novel Hybrid Process for the Conversion of Microcrystalline Cellulose To Value-Added Chemicals: Part 1: Process Optimization(Springer Verlag, 2016) Akın, Okan; Yüksel, AslıIn this paper, a novel hybrid process for the treatment of microcrystalline cellulose (MCC) under hot-compressed water was investigated by applying constant direct current on the reaction medium. Constant current range from 1A to 2A was applied through a cylindrical anode made of titanium to the reactor wall. Reactions were conducted using a specially designed batch reactor (450 mL) made of SUS 316 stainless steel for 30–120 min of reaction time at temperature range of 170–230 °C. As a proton donor H2SO4 was used at concentrations of 1–50 mM. Main hydrolysis products of MCC degradation in HCW were detected as glucose, fructose, levulinic acid, 5-HMF, and furfural. For the quantification of these products, High Performance Liquid Chromatography (HPLC) and Gas Chromatography with Mass Spectroscopy (GC–MS) were used. A ½ fractional factorial design with 2-level of four factors; reaction time, temperature, H2SO4 concentration and applied current with 3 center points were built and responses were statistically analyzed. Response surface methodology was used for process optimization and it was found that introduction of 1A current at 200 °C to the reaction medium increased Total Organic Carbon (TOC) and cellulose conversions to 62 and 81 %, respectively. Moreover, application of current diminished the necessary reaction temperature and time to obtain high TOC and cellulose conversion values and hence decreased the energy required for cellulose hydrolysis to value added chemicals. Applied current had diverse effect on levulinic acid concentration (29.9 %) in the liquid product (230 °C, 120 min., 2 A, 50 mM H2SO4). © 2016, Springer Science+Business Media Dordrecht.