Yazar "Copur, Mehmet" seçeneğine göre listele

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    CO2-Enhanced Synthesis of Trimethyl Borate from Ulexite: Innovations in Pervaporation Separation
    (Amer Chemical Soc, 2025) Ozekmekci, Mehtap; Copur, Mehmet; Unlu, Derya
    The primary objective of this research is to enhance a novel method for the eco-friendly production of trimethyl borate (TMB) from ulexite ore by utilizing carbon dioxide. Notably, CO2, a major greenhouse gas, is converted into thermodynamically stable CaCO3 following TMB synthesis. TMB, a significant organo-boron chemical, has a wide range of industrial applications. In this study, the trimethyl borate production process consists of three main steps: reaction, distillation, and pervaporation. Trimethyl borate was synthesized through the reaction of ulexite with methanol in a high-pressure reactor under a CO2 atmosphere. The obtained liquid product was subjected to distillation to produce the TMB-methanol azeotrope. Following the distillation process, the separation of TMB from the azeotrope mixture was achieved by utilizing pervaporation. The TMB-methanol azeotrope and pure TMB were characterized and confirmed by using Fourier transform infrared (FTIR) spectroscopy and gas chromatography (GC). In this research, hydroxyethyl cellulose (HEC) and polyvinylpyrrolidone (PVP) were used as the membrane materials. Blend membranes were prepared by the solution casting evaporation method. The morphologies of the membranes were characterized by FTIR spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and contact angle assessment. The pervaporation performance of all blend membranes was evaluated for the separation of the TMB-methanol azeotrope. The effects of the operating temperature, methanol feed concentration, and PVP ratios on separation performance were investigated. The results demonstrated that a TMB purity of 97.71 wt % was achieved when the PVP-HEC-2 membrane was utilized in pervaporation. In conclusion, this study introduces an innovative and environmentally friendly process for producing valuable chemicals, highlighting its potential for industrial applications.
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    Dissolution kinetics of ulexite with CO2 in methanol medium
    (Taylor & Francis Ltd, 2025) Ozekmekci, Mehtap; Copur, Mehmet
    In this study, the reaction kinetics of ulexite with CO2 in methanol were investigated in a pressurised reactor for the synthesis of trimethyl borate (TMB). The experimental parameters were varied as follows: temperature (T), 40-100 degrees C; solid-to-liquid ratio (SL), 0.05-0.2 g/mL; reaction time (t), 10-120 min; pressure (P), 10-30 bar; particle size (PS) 63-180 mu m; stirring speed (SS), 500-750 rpm. The results indicated that the dissolution rate increased with higher reaction temperatures and pressures, but decreased with larger particle sizes and higher solid to liquid ratio. However, stirring speed had no significant effect on the dissolution rate. It was observed that CaCO3 crystals that formed on the surface of the solid during the reaction, inhibiting the dissolution of the mineral. Calcium carbonate was produced in the aragonite phase without the use of additives. Thus, a method has been proposed to utilise CO2 and sequester it in a stable and permanent manner. In this study, a novel production process for trimethyl borate (TMB) was investigated, and the reaction mechanism was elucidated. A comprehensive analysis of the reaction mechanism related in the TMB synthesis process were obtained. For kinetic analysis, various empirical models were applied to fit the experimental data. Scanning Electron microscopy (SEM) and X-Ray diffraction (XRD) analyses were performed on the solid sample remaining after dissolution, and the results were supported by statistical analysis. The reaction rate was found to best described by the Avrami model. The activation energy of this process was calculated as 21 kJ/mol. Dans cette & eacute;tude, on a examin & eacute; la cin & eacute;tique de r & eacute;action de l'ulexite avec du CO2 dans le m & eacute;thanol, dans un r & eacute;acteur sous pression, pour la synth & egrave;se du borate de trim & eacute;thyle (TMB). Les param & egrave;tres exp & eacute;rimentaux variaient comme suit: temp & eacute;rature (T), 40 & agrave; 100 degrees C; rapport solide/liquide (SL), 0.05 & agrave; 0.2 g/ml; temps de r & eacute;action (t), 10 & agrave; 120 min; pression (P), 10 & agrave; 30 bar; taille des particules (PS), 63 & agrave; 180 mu m; vitesse d'agitation (SS), 500 & agrave; 750 tr/min. Les r & eacute;sultats ont indiqu & eacute; que le taux de dissolution augmentait avec des temp & eacute;ratures et des pressions de r & eacute;action plus & eacute;lev & eacute;es, mais diminuait avec des tailles de particules plus grandes et un rapport solide/liquide plus & eacute;lev & eacute;. Cependant, la vitesse d'agitation n'avait pas d'effet significatif sur le taux de dissolution. On a observ & eacute; que des cristaux de CaCO3, form & eacute;s & agrave; la surface du solide pendant la r & eacute;action, inhibaient la dissolution du min & eacute;ral. Du carbonate de calcium & eacute;tait produit dans la phase aragonite sans utilisation d'additifs. Ainsi, on a propos & eacute; une m & eacute;thode pour utiliser le CO2 et le s & eacute;questrer de mani & egrave;re stable et permanente. Dans cette & eacute;tude, on a examin & eacute; un nouveau proc & eacute;d & eacute; de production de borate de trim & eacute;thyle (TMB), et l'on a & eacute;lucid & eacute; le m & eacute;canisme de r & eacute;action. On a obtenu une analyse compl & egrave;te du m & eacute;canisme de r & eacute;action reli & eacute; au proc & eacute;d & eacute; de synth & egrave;se du TMB. Pour l'analyse cin & eacute;tique, on a appliqu & eacute; diff & eacute;rents mod & egrave;les empiriques pour ajuster les donn & eacute;es exp & eacute;rimentales. On a effectu & eacute; des analyses par microscopie & eacute;lectronique & agrave; balayage (MEB) et par diffraction des rayons X (XRD) sur l'& eacute;chantillon solide restant apr & egrave;s la dissolution, et les r & eacute;sultats ont & eacute;t & eacute; & eacute;tay & eacute;s par une analyse statistique. On a trouv & eacute; que le mod & egrave;le d'Avrami d & eacute;crivait le mieux le taux de r & eacute;action. On a calcul & eacute; l'& eacute;nergie d'activation de ce proc & eacute;d & eacute; & agrave; 21 kJ/mol.
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    Industrial symbiosis: Boron waste valorization through CO2 utilization
    (Korean Institute Chemical Engineers, 2022) Copur, Mehmet; Pekdemir, Turgay; Kocakerim, Mehmet Muhtar; Korucu, Haluk; Guliyev, Rovsen
    Various wastes being generated globally and dumped on land by mineral processing activities pose great ecological and health problems. An example is the boron mineral beneficiation solid wastes. Even greater threat is anthropogenic carbon dioxide (CO2) emissions among key causes of prevalent climate change. By this work, we propose a symbiotic solution to alleviate both environmental threats through recovering valuable boron products from boron wastes (BW), while also utilizing and sequestering CO2 stably and permanently. This article presents the results on the effect of important operation parameters for the performance of such a process within the following ranges determined by preliminary tests: temperature: 20-60 degrees C, solid-to-liquid ratio: 0.1-0.5 g/ml, reaction time: 15-120 min, stirring speed: 300-700 rpm and particle size: 150-600 mu m. CO2 gas (99.9%) flow rate was maintained continuously at 1.57 l/min under atmospheric pressure. The important findings are (1) per ton of BW production of commercially valuable either (a) 310 kg sodium penta-borate or (b) 350 kg sodium penta-borate mixed with Na2CO3, depending on the process configuration, (c) 725 kg relatively pure CaCO3, a potential source for precipitated calcium carbonate (PCC) and (d) 72 kg CO2 utilization, (2) effective parameters for CO2 utilization, in decreasing order are temperature, solid-to-liquid ratio and time, while stirring speed and particle size are ineffective within the range investigated and (3) the optimum operating conditions as: temperature: 60 degrees C, solid-to liquid ratio: 0.1 g/ml, time: 90 min, stirring speed: 500 rpm and particle size: <180 mu m.
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    Industrial Symbiosis: CO2 Utilization by Producing Disodium Octaborate Tetrahydrate and Baking Soda from Borax
    (Amer Chemical Soc, 2023) Copur, Mehmet; Senol, Ayse Merve; Pekdemir, Turgay; Onganer, Yavuz
    This paper proposesa novel method for CO2 capture,utilization, and sequestration (CCUS) with borax producing disodiumoctaborate tetrahydrate (Na2O & BULL;4(B2O3)& BULL;4H(2)O & EQUIV; Na2B8O13 & BULL;4H(2)O, DSOBTH) equivalent boron compoundsand sodium bicarbonate (NaHCO3). We tested the performanceof this method experimentally using aqueous ammonium (NH4 (+)) solutions in a pressurized reactor (1 L) continuouslypurged with pure (99.9%) CO2. Experimental parameters werechanged as temperature (T), 45-65 & DEG;C; solid-to-liquidratio (SLR), 0.69-0.92 g/mL; reaction time (t), 30-60 min; pressure (P), 5-30 bar;NH3 concentration (AC) 2.82-5.65 M; and steeringspeed (SS), 500 rpm. The results showed that P and T were highly influential on the performance. The best conditionsfor CO2 utilization were found as P =20 bar; T = 60 & DEG;C; SLR = 0.77 g/ml; t = 50 min; and AC = 4.76 M. Per ton of tincal, under theseconditions, produced were 0.274 ton of DSOBTH (& SIM;67% B2O3), 0.216 ton of NaHCO3 (& SIM;95% purity),0.386 ton of avoided boric acid, and 0.417 ton of avoided CO2. The total potential added value can be about $1100/ton of tincal.
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    Polyvinyl pyrrolidone-chitosan blend membrane for pervaporation separation of trimethyl boratemethanol mixture
    (Springer, 2025) Ozekmekci, Mehtap; Copur, Mehmet; Unlu, Derya
    Trimethyl borate (TMB) is an essential chemical for applications ranging from organic synthesis to borohydride production and requires efficient separation from methanol for optimal utilization. This study investigates the pervaporation performance of blend membranes composed of different ratios of chitosan (CS) and polyvinyl pyrrolidone (PVP) to improve the separation of TMB/methanol mixtures through pervaporation. The structural morphology, thermal properties, and crystalline nature of these membranes were comprehensively characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, contact angle measurements, scanning electron microscopy, and X-ray diffraction analysis. Pervaporation experiments were conducted by varying feed compositions, operating temperatures, and PVP ratios. The results demonstrated that increasing PVP content has a significant effect on permeation flux. The best conditions were obtained at 45 degrees C of operation temperature and 75% (by wt) TMB-25% (by wt) methanol mixture by utilizing a PVP-CS-2 membrane, recording flux value of 335.44 g/m2 h. Additionally, PVP-CS-1 and PVP-CS-2 blend membranes were subjected to a crosslinking process to evaluate their separation performance. The crosslinked PVP-CS-1 membrane showed a good performance, with a selectivity value of 146.37. Additionally, the crosslinked PVP-CS-2 membrane exhibited remarkable stability 5 run experiments, indicating strong chemical and mechanical endurance.