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    Facile “Green” synthesis of a novel Co–W–B catalyst from Rheum ribes shell extract and its effect on sodium borohydride hydrolysis: Kinetic mechanism
    (Elsevier Ltd, 2024) Ekinci, Arzu; Genli, Nasrettin; Şahin, Ömer; Baytar, Orhan
    The present investigation aimed to assess the influence of the Co–W–B NPs catalyst on the process of sodium borohydride hydrolysis. The study involved the synthesis of Co–W–B NPs through the utilization of an eco-friendly green synthesis extract derived from the Rheum ribes shell in conjunction with the chemical reduction technique for catalyst production. The investigation of catalysts' structure and surface morphology was conducted through the utilization of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) techniques. The average particle size was determined to be 35 nm in TEM analysis. The presence of Co–W–B nanoparticles and their elemental composition % were determined through EDX analysis, revealing values of 63.9% (Co), 31.89% (C), 1.75% (B), and 2.46% (W) within the nanoparticle. The manufactured Co–W–B catalyst's use for hydrolysis of sodium borohydride was studied under various conditions, including different concentrations of NaOH and NaBH4, different amounts of catalyst, and different temperature parameters. The hydrogen production rate for the Co–W–B NPs catalyst in NaBH4 hydrolysis was determined to be 5367 mLg?1min?1 at 30 °C. The study involved the determination of TOF values for a catalyst composed of Co–W–B NPs, which were subjected to varying temperatures. The activation energies were determined through the utilization of the n-th order and Langmuir-Hinshelwood kinetic models and subsequently calculated using the Arrhenius equation, resulting in values of 35.36 and 31.70 kJ/mol, respectively. The values of enthalpy and entropy, ?H and ?S, were determined through the utilization of Eyring's equation, 18.49 kJ/mol and ?80.7 J/mol.K, respectively. © 2023 Hydrogen Energy Publications LLC
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    Green synthesis of Co-based nanoparticles from Rheum ribes shell extract and determination of the effect of their activity on sodium borohydride hydrolysis
    (Springer Heidelberg, 2024) Baytar, Orhan; Sahin, Omer; Genli, Nasrettin; Ekinci, Arzu
    This study investigated the effect of Co(0) and Co-B NP catalysts synthesized by the green synthesis method using Rheum ribes shell extract on the NaBH4 hydrolysis process for the first time, and determined the role of the green synthesis method in the catalyst activity. The investigation of the structure and surface morphology of the catalysts was evaluated using XRD, SEM-EDX, TEM, FTIR, and XPS analyses. The effect of catalysts on NaBH4 was examined at different catalyst amounts, different NaBH4/NaOH concentrations, and different temperature values. The Co(0) and CoB NPs catalysts achieved the greatest HGR values at a solution temperature of 30 degrees C, with values of 7326 mLmin-1g-1cat and 12,524 mLmin-1g-1cat, respectively. The calculated activation energies for Co(0) and Co-B NPs catalysts are 37.68 kJmol-1 and 21.28 kJmol-1, respectively. The green synthesis method synthesized Co(0) and Co-B catalysts significantly increased hydrogen production activity compared to the cobalt-based catalysts synthesized by other methods.
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    Öğe
    Preparation and characterization of activated carbon from hydrochar by hydrothermal carbonization of chickpea stem: an application in methylene blue removal by RSM optimization
    (Taylor & Francis Inc, 2022) Genli, Nasrettin; Kutluay, Sinan; Baytar, Orhan; Sahin, Omer
    Herein, mesoporous activated carbon (AC) was prepared through potassium hydroxide (KOH) activation of hydrochar derived from the hydrothermal carbonization (HTC) of chickpea stem (CS), and successfully applied to remove methylene blue (MB) dye from aqueous solutions in a batch system. The HTC-CSAC was prepared depending on different impregnation ratios (hydrochar:KOH, 50-150%), impregnation times (12-48h), activation temperatures (400-600 degrees C) and activation times (30-60min). To define HTC-CSAC, various analytical techniques such as iodine adsorption number (IAN), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) were used. In the removal process of MB by the best HTC-CSAC with a high IAN of 887mg g(-1) obtained under conditions including impregnation ratio of 70%, activation time of 45min, activation temperature of 600 degrees C and impregnation time of 24h, the effects of adsorption parameters such as pH factor (2-10), adsorbent dosage (50-100mg), initial MB concentration (40-80mg/L) and contact time (90-180min) were studied. Besides, a detailed evaluation of the adsorption mechanism for the removal of MB by HTC-CSAC was performed. The Langmuir model indicated the best isotherm data correlation, with a maximum monolayer adsorption capacity (Q(max)) of 96.15mg g(-1). The adsorption isotherm findings demonstrated that the MB removal process is feasible, and that this process takes place through the physical interaction mechanism. Additionally, the HTC-CSAC adsorbent exhibited a high regeneration and reuse performance in MB removal. After five consecutive adsorption-desorption cycles, HTC-CSAC maintained the reuse efficiency of 77.86%. As a result, the prepared HTC-CSAC with a high BET surface area of 455m(2) g(-1) and an average pore diameter of 105 angstrom could be recommended as a promising and reusable adsorbent in the treatment of synthetic dyes in wastewaters.