WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article A Phenomenological Kinetic Flotation Model: Intrinsic Floatability Profiling for Batch and Continuous Flotation Systems(Springer Heidelberg, 2026) Polat, Mehmet; Guzel, Veli; Kobas, Muammer; Polat, HurriyetThis study presents a mechanistic flotation kinetics model that unifies the description of mineral particle floatability in both batch and continuous systems. Building on a physically explicit interpretation of bubble-particle interactions, the model introduces the concept of intrinsic floatability, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\upphi }_{\text{P},\text{ij}}<^>{\text{s}}$$\end{document}, defined as the size-and composition-dependent probability that a particle within a bubble's sweep volume reports to the froth. A central feature of the framework is that \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\upphi }_{\text{P},\text{ij}}<^>{\text{s}}$$\end{document} is decoupled from system-level rate-determining factors, such as bubble-particle encounter frequency, transport limits, and bubble surface crowding-that otherwise confound attempts to extract floatability distributions from kinetic data. This separation is achieved through three explicit, time-dependent parameters: the encounter rate kappa(t), the limiting flotation rate mu(t), and the bubble saturation factor chi(t). Together, these parameters isolate intrinsic particle behavior from external constraints. The model naturally reduces to the classical first-order rate law in dilute pulps, while in concentrated suspensions it predicts systematic deviations, approaching zero-order kinetics as bubble surfaces saturate. Importantly, the same formulation applies seamlessly to batch tests and multi-stage continuous circuits, enabling a consistent theoretical framework across scales and ore types. Requiring only standard flotation data and known system parameters, the model is practical for both laboratory coal flotation studies and industrial non-coal applications. Validation using batch coal data and continuous plant-scale copper flotation results demonstrates its robustness and broad relevance.Article Citation - WoS: 11Citation - Scopus: 11Renewable-Based Treatment Solution of Reactive Blue 21 Dye on Fly Ash as Low-Cost and Sustainable Adsorbent(Elsevier, 2024) Kobya, Mehmet; Dolaz, Mustafa; Goren, Aysegul YagmurThis study investigated the removal of Reactive Blue 21 (RB 21) dye from aqueous solutions by adsorption, evaluating the waste fly ash (FA). The effects of the parameters, such as initial dye concentration (100-750 mg/ L), initial pH (2.0-8.0), adsorbent dose (1.0-4.0 g/L), and temperature (298-323 K) on the adsorption process were investigated. The optimum initial pH value was 2.0 for the highest RB21 dye removal (75.2 mg/g). At optimized conditions (pH 2.0, an adsorbent dosage of 1.0 g/L, a dye concentration of 750 mg/L, and an equilibrium time of 72 h), the highest adsorption capacity was found to be 105.2 mg/g. Moreover, the results of the kinetic studies fitted the pseudo-second-order kinetic model. Equilibrium data were best represented by the Langmuir isotherm model, with a maximum monolayer adsorption capacity of 103.41 mg/g at 323 K. Delta G0ads values were negative and varied from 11.64 to 9.50 kJ/mol in the temperature range of 298-323 K, the values of enthalpy (Delta Ho ads) and entropy (Delta So ads) of thermodynamics parameters were calculated as 37.62 kJ/mol and 86.67 J/mol K, respectively, indicating that this process was endothermic. Furthermore, the adsorbent costs for powdered activated carbon (PAC) and FA to remove 1 kg of RB 21 dye from aqueous solutions are calculated as 2.52 U.S. $ and 0.34 U.S. $, respectively. It is seen that the cost of FA is approximately 7.4 times lower than PAC. The results showed that FA, a low-cost industrial waste, was promising for the adsorption of RB 21 from aqueous solutions.Data Paper Citation - WoS: 15Citation - Scopus: 20Database Covering the Prayer Movements Which Were Not Available Previously(Nature Publishing Group, 2023) Mihçin, Şenay; Şahin, Ahmet Mert; Yılmaz, Mehmet; Alpkaya, Alican Tuncay; Tuna, Merve; Akdeniz, Sevinç; Can, Nuray Korkmaz; Tosun, Aliye; Şahin, SerapLower body implants are designed according to the boundary conditions of gait data and tested against. However, due to diversity in cultural backgrounds, religious rituals might cause different ranges of motion and different loading patterns. Especially in the Eastern part of the world, diverse Activities of Daily Living (ADL) consist of salat, yoga rituals, and different style sitting postures. A database covering these diverse activities of the Eastern world is non-existent. This study focuses on data collection protocol and the creation of an online database of previously excluded ADL activities, targeting 200 healthy subjects via Qualisys and IMU motion capture systems, and force plates, from West and Middle East Asian populations with a special focus on the lower body joints. The current version of the database covers 50 volunteers for 13 different activities. The tasks are defined and listed in a table to create a database to search based on age, gender, BMI, type of activity, and motion capture system. The collected data is to be used for designing implants to allow these sorts of activities to be performed.Article Citation - WoS: 4Citation - Scopus: 4Effect of Oxidation on Mechanical Properties of Copper Nanowire: a Reaxff (reactive Force Field) Molecular Dynamics Study(Aip Publishing, 2023) Aral, Gürcan; Islam, Md MahbubulNanostructures with high surface area to volume ratio, such as oxidized and coated Cu nanowires (NWs), exhibit unique mechanical properties due to their size and surface effects. Understanding the complex oxidation process of Cu NWs at nanoscale and quantifying its resulting effects on mechanical behavior and properties are significantly essential for effective usage of Cu NW devices in a wide range of applications in nanoelectronics. Here, we perform molecular dynamics simulations using ReaxFF (reactive force field) to investigate the oxidation process and mechanisms of [001]-oriented cylindrical Cu NWs and its contribution on the mechanical deformation behavior and material properties as a function of NW sizes. The relatively thin oxide CuxOy layer is formed on the surface of Cu NWs in an O-2 environment, creating a core/shell (Cu/CuxOy) NW structure that played a key role in governing the overall tensile mechanical deformation behavior and properties of Cu NW. The formation of oxide layer effects, including the resulting interface and defects, leads to a reduction in the initial dislocation nucleation barrier, which facilitates the onset of plasticity and stress relaxation, ultimately resulting in a negative impact on the tensile strength, Young's modulus, yield stress and strain, and flow stress when compared to pristine counterparts. It is worth noting that the tensile mechanical response and properties of the Cu NWs are highly dependent on the pre-existing oxide shell layer associated with the size of NW, determining the overall mechanical performance and properties of Cu NWs.Article Citation - WoS: 14Citation - Scopus: 15Investigation of the Effect of Gel Properties on Supercritical Drying Kinetics of Ionotropic Alginate Gel Particles(Elsevier, 2019) Şahin, İbrahim; Uzunlar, Erdal; Erkey, CanA series of spherical ionotropic alginate gel particles with different diameters ranging from 2.8mm to 5.0mm and porosities ranging from 0.899 to 0.976 were prepared by dripping a Na-alginate solution into a solution of salts of divalent cations (Ca2+, Mn2+, Ni2+, Co2+, Cu2+ and Zn2+). After solvent exchange with ethanol, kinetics of supercritical drying of these ionotropic alginate gel particles in a packed bed was investigated at 308-338 K and 100-120 bar. Experimental data were compared with predictions of a model which considers diffusive transport inside the pores and convection in the flowing fluid stream. The model predicted drying profiles by taking into account only the changes in porosity and diameter of the gel particles. A convective mass transfer coefficient correlation that was originally developed for supercritical drying of Ca-alginate gel particles was found to be suitable for M-alginate gel particles. (C) 2019 Elsevier B.V. All rights reserved.Article Citation - WoS: 23Citation - Scopus: 24Investigation of Kinetics of Supercritical Drying of Alginate Alcogel Particles(Elsevier Ltd., 2019) Şahin, İbrahim; Uzunlar, Erdal; Erkey, CanSpherical calcium alginate gel particles were synthesized by dripping method. The effects of temperature, pressure, particle size and CO2 flow rate on kinetics of supercritical drying of alginate gel particles in a packed bed were investigated. Increase in CO2 flow rate, increase in temperature and decrease in particle size increased the drying rate and decreased the drying time. A mathematical model based on (i) the diffusion of the solvent inside the pores of gel particles, (ii) external mass transfer of the solvent from the surface of the gel particles into the flowing fluid stream, and (iii) convection and axial dispersion of the solvent in the flowing fluid stream was developed. A correlation for predicting external mass transfer coefficients for supercritical drying of alcogel particles was developed by fitting the model to experimental data. A good agreement between the experimental data and model results was achieved using the developed correlation.Article Citation - WoS: 13Citation - Scopus: 17Effect of Ultrasound on the Kinetics of Cation Exchange in Nax Zeolite(Elsevier Ltd., 2012) Erten Kaya, Yasemin; Çakıcıoğlu Özkan, FehimeIn this study, we focused on the effect of ultrasound on ion exchange kinetics to obtain the Li-, Ca- and Ce-rich NaX zeolite. The results were compared to those obtained from the traditional batch exchange method under similar conditions. Contact time and initial cation concentration (fold equivalent excess) were studied. Ultrasound enhanced the replacement of Na + ion with Li +, Ca 2+ and Ce 3+ ions in the extra-framework of zeolite up to 76%, 72% and 66%, respectively. The intraparticle diffusion is the rate limiting step in the ion exchange for both exchange methods. As compared to the traditional exchange method, the ultrasonic method applied in this study was found to be very effective on the exchange amount at equilibrium.Article Citation - WoS: 19Citation - Scopus: 20Isothermal Crystallization Kinetics and Mechanical Properties of Polycaprolactone Composites With Zinc Oxide, Oleic Acid, and Glycerol Monooleate(John Wiley and Sons Inc., 2013) Alp, Burcu; Cesur, SerapThe isothermal crystallization and mechanical behavior of polycaprolactone (PCL) with zinc oxide (ZnO) with oleic acid and glycerol monooleate (GMO) were studied. Theoretical melting points calculated by the Flory-Huggins and Thompson-Gibbs models were thoroughly compared with differential scanning calorimetry experimental observations. The isothermal crystallization kinetic parameters by Avrami analysis showed that crystallization was controlled by nucleation, crystal growth was spherical, and the nucleation type changed between thermal and athermal nucleation. X-ray diffraction showed that when the additives were used together both the crystal thickness and the degree of crystallinity increased. A multiple-response regression analysis was made with the ZnO, oleic acid, and GMO concentrations as variables and the crystallinity as output. Interaction parameters by the Pukanzky model were calculated from the tensile strength at the yield point and indicated that the addition of oleic acid or GMO improved the interface between the ZnO particles and PCL.Article Citation - WoS: 21Citation - Scopus: 23Adsorption of Methylene Blue From Aqueous Solution on High Lime Fly Ash: Kinetic, Equilibrium, and Thermodynamic Studies(Taylor and Francis Ltd., 2012) Keleşoğlu, Serkan; Kes, Mürşide; Sütçü, Leman; Polat, HürriyetKinetic, equilibrium, and thermodynamic studies were performed for the batch adsorption of methylene blue (MB) on the high lime fly ash as a low cost adsorbent material. The studied operating variables were adsorbent amount, contact time, dye concentration, and temperature. The kinetic data were analyzed using the pseudo-first order and pseudo-second order kinetic models and the adsorption kinetic was followed well by the pseudo-second order kinetic model. The equilibrium data were fitted with the Freundlich, Langmuir, and Dubinin Radushkevich (D-R) isotherms and the equilibrium data were found to be well represented by the Freundlich and D-R isotherms. Based on these two isotherms MB is taken by chemical ion exchange and active sites on the high lime fly ash have different affinities to MB molecules. Various thermodynamic parameters such as enthalpy of adsorption (ΔH°), free energy change (ΔG°), and entropy change (ΔS°) were investigated. The positive value of ΔH° and negative value of ΔG° indicate that the adsorption is endothermic and spontaneous. The positive value of ΔS° shows the increased randomness at the solid-liquid interface during the adsorption. A single-stage batch adsorber was also designed based on the Freundlich isotherm for the removal of MB by the high lime fly ash. © 2012 Copyright Taylor and Francis Group, LLC.Article Citation - WoS: 12Citation - Scopus: 13Statistical Thermal Stability of Pvc(John Wiley and Sons Inc., 2010) Atakul Savrık, Sevdiye; Cansever Erdoğan, Beyhan; Balköse, Devrim; Ülkü, SemraExperimental design was used to optimize the processing parameters for the decomposition of poly (vinyl chloride). Factorial design and face centered composite design (FCC) were applied to determine the optimum conditions. A total of 10 g PVC powder was mixed with different amounts of zinc stearate (ZnSt 2) and natural zeolite and tested for thermal stability. Factorial fitted model was explained by first order pattern due to the significant main effect regression constants, and FCC model was described by second order model owing to higher order polynomial coefficients. FCC design was superior to factorial design as FCC considers not only its pure quadratic effects contribution but also its higher overall desirability for thermal stability of PVC. For factorial design the optimum conditions were determined as 163.06 mg for ZnSt2, 399.99 mg for zeolite, and 140°C for temperature with desirability of 0.933. However, 400 mg for ZnSt2, 333.24 mg for zeolite, and 140°C for temperature with desirability of 0.956 were obtained as the optimum conditions by FCC design. © 2010 Wiley Periodicals, Inc.