Yazar "Çopur, Mehmet" seçeneğine göre listele
Listeleniyor 1 - 13 / 13
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Determination of Optimal Conditions for Retention of Sulfur Dioxide by Waste Ulexite Ore in an Aqueous Medium(Taylor & Francis Inc, 2017) Çopur, Mehmet; Karagoz, Ozlem; Kocakerim, M. MuhtarThe main aim of this study was to remove sulfur dioxide (SO2), which is one of the most significant air pollutants emitted from thermal power stations, using waste ulexite ore, which cannot be recycled industrially and poses a risk for the environment. In experiments conducted at atmospheric pressure in an aqueous environment, the optimization of holding SO2 with waste ulexite ore has been investigated comprehensively and determined how much SO2 could be retained in solid waste. The Taguchi method was used to determine the optimal conditions, and the effectiveness of the parameters was identified by variance analysis. The selected parameters and their ranges were defined as temperature (293-333 K), solid to liquid ratio (0.4-0.6 g mL(-1)), particle size (150-600 mu m), time (10-30 min), pH (5.5-7.5), and stirring speed (350-800 rpm). The optimal conditions for these parameters were determined to be 333 K, 0.45 g mL(-1), 250 mu m, 15 min, pH 6, and 350 rpm, respectively. Among all the parameters, temperature and pH were found to be the most effective. The results of the study revealed that SO2 can be retained in solid waste with calcium content of the boron minerals as CaSO3 center dot 0.5H(2)O and nearly whole B2O3 in the waste ulexite passes into solution. Under the optimum conditions, 86% of B2O3 passed into the solution and 75.2 L SO2 was retained by 1 kg waste ulexite ore. Thus, both B2O3 recovery and SO2 removal were materialized, while waste ulexite ore was evaluated and removed, simultaneously.Öğe Determination of the Optimum Conditions for Copper Leaching from Chalcopyrite Concentrate Ore Using Taguchi Method(Taylor & Francis Inc, 2015) Çopur, Mehmet; Kizilca, Meltem; Kocakerim, M. MuhtarThe optimum conditions for the extraction of copper from chalcopyrite concentrate into SO2-saturated water were evaluated using the Taguchi optimization method. High level copper recovery was obtained in an environmentally friendly process that avoids sulfur dioxide emission into the atmosphere because SO2 forming in the roasting is used in the dissolution. Experimental parameters and their ranges were chosen as follows: reaction temperature, 293-333 K; solid-to-liquid ratio, 0.025-0.15 g/mL; roasting time, 30-90 min; roasting temperature, 773-973 K; stirring speed, 400-800 rpm; and reaction time, 10-60 min. The particle size and gas flow rate were 63 mm and 10 cm(3)/min, respectively. The optimum conditions of the dissolution process were determined to be reaction temperature of 318 K, a solid-to-liquid ratio of 0.025 gmL(-1), a roasting time of 75 min, a roasting temperature of 773 K, a stirring speed of 400 rpm, and a reaction time of 30 min. Under optimum conditions, dissolution yield of copper was 91%.Öğe Investigation of the Thermal Decomposition Kinetics of Chalcopyrite Ore Concentrate usng Thermogravimetric Data(Taylor & Francis Inc, 2016) Kizilca, Meltem; Çopur, MehmetThe kinetics of the thermal decomposition of chalcopyrite concentrate was investigated by means of thermal analysis techniques, Thermogravimetry/Derivative thermogravimetry (TG/DTG) under ambient air conditions in the temperature range of 0-900 degrees C with heating rates of 2, 5, 10, 15, and 20 degrees C min(-1). TG and DTG measurements showed that the thermal behavior of chalcopyrite concentrate shows a two-step decomposition. The decomposition mechanism was confirmed using X-ray diffraction (XRD), Scanning Electron Microscope (SEM)/energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR) analyses. Kinetic parameters were determined from the TG and DTG curves for steps I and II by using two model-free (isoconversional) methodsFlyn-Wall-Ozowa (FWO) and Kissinger-Akahira-Sunose (KAS). The kinetic parameters consisting of E-a, A, and g() models of the materials were determined. The average activation energies (E-a) obtained from both models for the decomposition of chalcopyrite concentrate were 72.55 and 300.77kJmol(-1) and the pre-exponential factors (A) were 15.07 and 29.39 for steps I and II, respectively. The most probable kinetic model for the decomposition of chalcopyrite concentrate is an first-order mechanism, i.e., chemical reaction [g()=(-ln(1-))], and an Avrami-Eroeyev equation mechanism, i.e., nucleation and growth for n=2 [g()=(-ln(1-)(1/2))], for steps I and II, respectively.Öğe Kinetic analysis of retention of SO2 using waste ulexite ore in an aqueous medium(Elsevier Science Bv, 2018) Karagoz, Ozlem; Çopur, Mehmet; Kocakerim, M. MuhtarThis study was carried out under atmospheric pressure and examined the kinetics of retention of SO2, a toxic gas, by waste ulexite ore (WUO) from a boron concentration plant, as well as the kinetics of passing B2O3 content of WUO to solution. The parameters of temperature, solid-to-liquid ratio, particle size, gas flow rate, and stirring speed were selected for the experiments carried out in a jacketted cylindirical glass reactor. The data on retention-dissolution and an XRD graph showed that SO2 had been captured as CaSO3 center dot 0.5H(2)O, and that the B2O3 content of WUO had almost completely passed into the aqueous medium. A kinetic evaluation, performed with the retention-dissolution data using kinetic models for heterogenous reactions, found that the kinetics model for SO2 retention fitted diffusion through product layer control. In addition, the kinetics model for the B2O3 dissolution fitted the diffusion through product film control. Activation energies for SO2 retention in solid waste and B2O3 dissolution were 6196 J mol(-1) and 15436 J mol(-1) respectively.Öğe Kinetic Investigation of Reaction Between Colemanite Ore and Methanol(Taylor & Francis Inc, 2015) Kizilca, Meltem; Çopur, MehmetIn the field of industry, it is very important that boron compounds are produced from boron ores. The aim of this study was to investigate the dissolution kinetics with carbon dioxide of colemanite in methanol medium in a pressure reactor and to derive an alternative process for producing boron compounds. Reaction temperature, stirring speed, solid/liquid ratio, pressure, and particle size were selected as parameters for the dissolution rate of colemanite. It was found that the dissolution rate increased with increase in pressure and reaction temperature, and with decrease in particle size and solid/liquid ratio. No effect of stirring speed was observed on conversion. The dissolution kinetics of colemanite were examined using both heterogeneous and homogeneous reaction models, and it was determined that the reaction rate can be described by a second-order pseudo-homogeneous reaction model. The activation energy was found to be 51.4 kJ/mol.Öğe NaOH production by electro-dialysis of borax solution in an electrochemical flow cell(Atatürk Üniversitesi, 2025) Kesmen, Elif; Çopur, Mehmet; Yapıcı, Sinan; Arzutuğ, Mehmet EminIn this study, the production of sodium hydroxide from borax, which is an important boron mineral, was investigated by the electrolysis of borax solution in a cation exchange membrane unit in which three-dimensional carbon felt electrodes were used. During the experiments, the effects of electrolyte flow rate, the concentration of borax solution, and system temperature on the concentration of produced sodium hydroxide were studied. The effect of parameters on the sodium hydroxide production were investigated for four different electrolyte flow rates in the range of 0.024-0.039 m s-1, the effect of concentration of borax solution for four different concentrations of borax solution in the range of 0.18-0.43 M, and the effect of system temperature for three different temperature in the range of 40-60°C. It was observed that as the rate of electrolyte and the concentration of borax solution increased, sodium hydroxide production also increased. But the increase in temperature had an adverse effect on sodium hydroxide production.Öğe Performance evaluation of cellulose acetate (CA)/polyvinylpyrrolidone (PVP) membranes in the pervaporation separation of trimethyl borate/methanol azeotrope(Turkish Energy, Nuclear and Mining Research Agency, 2025) Ozekmekci, Mehtap; Çopur, MehmetIn this study, the performance of cellulose acetate (SA)/polyvinylpyrrolidone (PVP) blend membranes for the separation of trimethyl borate (TMB)/methanol azeotrope was investigated. The membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-Ray diffractometer (XRD), thermogravimetric analysis (TGA) and contact angle measurements. The characteristic XRD peak intensity and contact angle of SA decreased with increasing PVP ratio. The effect of PVP ratio, feed temperature and methanol concentration in the feed were investigated in the pervaporation process. It was observed that flux increased and selectivity decreased with increasing PVP ratio. Feed temperature was found to have a positive effect on flux. The increase in the amount of methanol in the feed concentration caused the polymer chains to become more flexible, facilitating the diffusion of both methanol and TMB. Additionally, the reusability of the membrane was tested, and its physical and chemical structure integrity was confirmed by FTIR and SEM analyses. The optimum operating conditions for the SA-PVP-3 membrane were found to be 35°C temperature and azeotrope containing 25 wt% methanol. Under these operating conditions, the flux and selectivity were determined as 302.08 g/(m2h) and 46.92, respectively. © 2025, Turkish Energy, Nuclear and Mining Research Agency. All rights reserved.Öğe PVA/ Amberlit IRA 743 Hibrit Membran İle Endüstriyel Atık Sudan Bor Giderimi(2021) Özekmekci, Mehtap; Ünlü, Derya; Çopur, MehmetBu çalışmada, pervaporasyon prosesi ile endüstriyel atık sudan borun uzaklaştırılması incelenmiştir. Bu işlem için Saf PVA ve Amberlit IRA 743 katkılı PVA membranlar hazırlanmıştır. SEM analizinde, saf membranlarda yoğun ve homojen bir yapı gözlenirken, katkılı membranda Amberlit IRA 743 dağılımı açıkça görülmektedir. Amberlit IRA743 ilavesinin ve çapraz bağlanmanın membranın kimyasal bağ yapısında meydana getirdiği değişimler Fourier dönüşümlü kızılötesi (FTIR) spektroskopisi ile belirlenmiştir. Membranların suya karşı ilgisi şişme testi ile belirlenirken, yüzey hidrofilikliği temas açısı ölçümleriyle araştırılmıştır. Sıcaklığın ve Amberlit IRA 743 yükleme oranının membranın ayırma performansına etkisi incelenmiştir. Sıcaklığın artması suyun akısını artırırken bor giderimine önemli bir etkisi olmamıştır. Amberlit IRA 743 miktarının artması ile suyun akısı azalırken bor giderimi artmıştır. PVA/Amberlit IRA 743 membranların endüstriyel atık sulardan bor gideriminde yüksek ayırma performansı gösterdiği ve %99’dan daha fazla oranda bor giderildiği tespit edilmiştir.Öğe Removal of boron from industrial wastewater using PVP/PVDF blend membrane and GO/PVP/PVDF hybrid membrane by pervaporation(Springer, 2021) Özekmekçi, Mehtap; Ünlü, Derya; Çopur, MehmetRemoval of boron from water is a significant issue worldwide. Boron levels in waters containing high concentrations should be kept under control. Boron removal from the industrial wastewater released from Eti Mine Boron plants was investigated by using blend and hybrid membranes in a laboratory-scale pervaporation system. Polyvinylpyrrolidone/Polyvinylidene fluoride blend membrane and Graphene oxide/Polyvinylpyrrolidone/Polyvinylidene fluoride hybrid membranes were synthesized for this process. The membranes were characterized by using scanning electron microscopy, Fourier transform infrared, X-ray diffraction and contact angle measurements. Separation performance was evaluated in terms of flux, removal ratio of boron, and boron concentration in permeate within the membrane. Membranes showed higher separation performance in industrial wastewater. The highest boron removal was obtained as 99.86% with a flux of 0.755 kg/m2h when the 8 wt% graphene oxide loaded hybrid membrane was used. This study indicates that the Polyvinylpyrrolidone and Graphene oxide addition improved the membrane features and separation performances of the pervaporation process with improved hydrophilic membrane features can be preferred as an innovative water treatment method for the removal of boron from industrial wastewater. The obtained results show that pervaporation can be readily adapted to the removal of boron species by appropriate membrane selection.Öğe Synthesis of CaCO3 and trimethyl borate by reaction of ulexite and methanol in the presence of CO2(Elsevier Sci Ltd, 2020) Özekmekçi, Mehtap; Çopur, MehmetDeveloping CO2 capture and use of technologies to reduce anthropogenic emissions can be part of the solution against climate change. The purpose of this study is to develop a novel method to synthesize CaCO3 and trimethyl borate solution by utilizing and capturing carbon dioxide in a high pressure reactor. Dissolution of ulexite has been investigated to determine the effect of important working parameters by using Taguchi method. The parameters and their ranges were given as follows: reaction temperature, 80-120 degrees C; pressure, 10-30 bar; solid-to liquid ratio, 5/100-20/100 g/mL; particle size,-106 + 75 mu m-212 + 154 mu m; stirring speed, 500-750 rpm; reaction time, 20-60 min. The findings of this research were given as follows: (1) the optimum operational conditions were found to be reaction temperature 120 degrees C, pressure 30 bar, solid to liquid ratio 0.05 g/ml, stirring speed 750 rpm, reaction time 60 min, particle size -154 + 106 mu m, (2) 92.94 %of B2O3 was taken into solution under optimum condition (2) the sequestration capacity of CO2 was found to be 188 kg per ton ulexite (3) characterization of products by FTIR, SEM, XRD and ICP-OES confirmed that trimethyl borate and CaCO3 were synthesized. The utilization of CO2 in this process could sequester a considerably amount of CO2, therefore it can be contribute to decrease CO2 emission that causes greenhouse effect.Öğe The Conversion Kinetics of Tincal to Boric Acid in Nitric Acid Solutions(Jihad Daneshgahi, 2020) Mehmet, Tunc; Hasan, Irem; Muhtar, M. Kocakerim; Çopur, Mehmet; Ozkan, KucukPure borax and various boron compounds are produced from the solutions in which tincal is dissolved with various reagents. Economically important boron compounds such as boric acid, borax, boric oxide, and refined hydrated sodium borates and perborates are produced from boroncontaining ores. The production of boric acid by using nitric acid from tincal is more advantageous because it evaluates by-product NaNO3 as fertilizer production. In this study, the conversion kinetics of tincal to boric acid in nitric acid solutions were investigated by such parameters as particle size, 300-1500 mu m; acid concentration,0.5-4 mol/L; solid-to-liquid ratio 0.04-0.10 g/mL; stirring speed 20.93-62.8 s(-1), and reaction temperature, 30-60 degrees C. The conversion was found to increase with decreasing particle size and solid-to-liquid ratio and while it increased with increasing reaction temperature, acid concentration, and stirring speed. The conversion kinetics was examined using the heterogeneous and pseudo-homogeneous reaction models. The experimental results were found to be in better agreement with the correlation given in the following equation and the activation energy being 37.5 kJ/mol. ln(1-XHNO3/1-X-tincal)=(C-0,C-HNO3, 2C(0,tincal))ktÖğe Thermal dehydration of colemanite: kinetics and mechanism determined using the master plots method(Taylor & Francis Ltd, 2017) Kizilca, Meltem; Çopur, MehmetDehydration kinetics of colemanite ore were explored using thermogravimetric analysis techniques (thermogravimetry (TG)/derivative thermogravimetry (DTG)) in the range of 0-1000 degrees C at heating rates of 2, 5, 10 and 20 degrees C min(-1) in an inert (N-2) atmosphere. Kinetic triplets which were activation energy, pre-exponential factor and reaction mechanism were obtained from the TG and DTG applying six model-free (isoconversional) methods, i.e. Kissinger-Akahira-Sunose (KAS); Flyn-Wall-Ozawa (FWO); Tang, Starink and iterative KAS and iterative FWO. The researcher tested the reliability of the study method in identifying the kinetic mechanism by comparing experimental master plots to theoretical master plots. Structural and morphological properties were carried out using X-ray diffraction, Fourier transform infrared and scanning electron microscopy-energy disperse spectroscopy methodologies.Öğe Trimetil borat/metanol azeotropunun pervaporasyonla ayrılmasında selüloz asetat (SA)/ polivinilpirolidon (PVP) membranların performans değerlendirmesi(2025) Ozekmekci, Mehtap; Çopur, MehmetBu çalışmada trimetil borat (TMB)/metanol azeotropunu ayırmak için selüloz asetat (SA)/ polivinilpirolidon (PVP) blend membranların performansı incelenmiştir. Membranlar, Fourier dönüşümlü kızıl ötesi spektroskopisi (FTIR), taramalı elektron mikroskopisi (SEM), X-Ray difraktometresi (XRD), termogravimetrik analiz (TGA) ve temas açısı ölçümleri ile karakterize edilmiştir. PVP oranındaki artma ile SA’nın karakteristik XRD pik şiddeti ve temas açısı küçülmüştür. Pervaporasyon prosesinde PVP oranının, besleme sıcaklığının ve beslemedeki metanol konsantrasyonunun etkisi incelenmiştir. Artan PVP oranıyla akının arttığı, seçiciliğin azaldığı gözlemlenmiştir. Besleme sıcaklığının akı üzerinde olumlu bir etkiye sahip olduğu tespit edilmiştir. Besleme konsantrasyonundaki metanol miktarının artması, polimer zincirlerinin daha esnek hale gelmesine neden olarak hem metanolün hem de TMB’nin difüzyonunu kolaylaştırmıştır. Ayrıca membranın tekrar kullanılabilirliği test edilmiş olup fiziksel ve kimyasal bütünlüğünü koruduğu yapılan FTIR ve SEM analizleriyle doğrulanmıştır. SA-PVP-3 membranı için en uygun çalışma koşulları, 35°C sıcaklık ve ağırlıkça %25 metanol içeren azeotrop olarak tespit edilmiştir. Bu çalışma koşulları altında akı ve seçicilik sırasıyla 302,08 g/(m2sa) ve 46,92 olarak belirlenmiştir.
