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    Adsorption of copper (II) from aqueous solutions using adsorbent obtained with sodium hydroxide activation of biochar prepared by microwave pyrolysis
    (Springer Heidelberg, 2024) Tegin, Ibrahim; Oc, Sema; Saka, Cafer
    Microwave heating is one of the leading methods that save energy, time, and cost for the conversion of bio-waste into biochar in the agricultural sector. In this study, in the first stage, economical biochar production from pistachio green hulls by microwave heating method is in question. In the second step, sodium hydroxide(NaOH) activation was followed to improve the surface properties of biochar. This adsorbent obtained was applied to remove copper ions(Cu(II)) from wastewater. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), thermogravimetry differential thermal analysis (TG/DTG), and nitrogen adsorption/desorption methods were used to characterize the biochar samples. In adsorption studies, kinetic, isotherm, and thermodynamic parameters were investigated. Cu(II) adsorption capacity on modified biochar obtained by Langmuir isotherm was found to be 227.27 mg/g. In addition, the mechanism of Cu(II) adsorption on modified biochar has been proposed. Biochar, which is obtained from the green shells of pistachios, which is widely available and grown in Turkey, by microwave method and then NaOH activation, is a potential solution for both the improvement of water pollution caused by heavy metals and the disposal of related wastes with an appropriate method.
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    An Overview of Analytical Methods for the Determination of Monoamine Oxidase Inhibitors in Pharmaceutical Formulations and Biological Fluids
    (Taylor & Francis Inc, 2017) Saka, Cafer
    Monoamine oxidase inhibitors (MAOIs) were the first type of antidepressant developed. MAOIs elevate the levels of norepinephrine, serotonin, and dopamine by inhibiting an enzyme called monoamine oxidase. They are also used in the treatment of Parkinson's disease, tuberculosis, and several other disorders. Therefore, it is very important to develop efficient analytical methods for monitoring and management. There are two isoforms of monoamine oxidase, MAO-A and MAO-B. In this article, analyses of MAOIs in pharmaceutical formulations and biological fluids were reviewed from 2000 to the present, including all types of chromatographic, spectrophotometric, electrophoretic, and voltammetric techniques, focusing on isoniazid, tranylcypromine, moclobemide, rasagiline, and selegiline.
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    Analytical methods for determination of selective serotonin reuptake inhibitor antidepressants
    (Walter De Gruyter Gmbh, 2011) Senturk, Zuhre; Saka, Cafer; Tegin, Ibrahim
    Selective serotonin reuptake inhibitors (SSRIs) are commonly used to treat depression. SSRIs are classified as fluoxetine, paroxetine, escitalopram, citalopram, sertraline, and fluvoxamine. Several methods have been published for the determination of SSRI drugs in pharmaceuticals, biological materials and environmental samples. This review covers the analytical methods described in the literature for the determination of SSRIs and their main metabolites or some compounds belonging to the same SSRI group. The analytical methods are generally chromatography based methods coupled to different detectors, electroanalytical methods, capillary zone electrophoretic methods, and spectrometric methods.
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    Analytical Methods on Determination in Pharmaceuticals and Biological Materials of Chloroquine as Available for the Treatment of COVID-19
    (Taylor & Francis Inc, 2022) Saka, Cafer
    With the outbreak caused by the severe acute respiratory syndrome coronavirus (COVID-19), people's health and existing economies on a global scale are seriously threatened. Currently, most of the countries all over the world are studying extensively to better understand the antimalarial chloroquine (CQ) and hydroxychloroquine (HCQ) for therapeutic purposes due to the COVID-19 outbreak. However, CQ and HCQ can have serious side effects, from psychiatric effects to sudden death. Therefore, a faster and more effective detection method is needed to monitor drug concentrations. In this review, a large study was conducted on the detection techniques and quantitative determination methods of CQ and its related metabolites. In this review, chromatography, electrophoresis, electroanalytical, spectroscopic, and immunological methods for CQ and related metabolites are discussed extensively. It is hoped that a better understanding of the CQ used for therapeutic purposes in the COVID-19 outbreak will be provided.
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    Analytical Strategies for the Determination of Norepinephrine Reuptake Inhibitors in Pharmaceutical Formulations and Biological Fluids
    (Taylor & Francis Inc, 2016) Saka, Cafer
    Norepinephrine reuptake inhibitors (NRIs) are a class of antidepressant drugs that act as reuptake inhibitors for the neurotransmitters norepinephrine and epinephrine. The present review provides an account of analytical methods published in recent years for the determination of NRI drugs. NRIs are atomoxetine, reboxetine, viloxazine and maprotiline. NRIs with less activity at other sites are mazindol, bupropion, tapentadol, and teniloxazine. This review focuses on the analytical methods including chromatographic, spectrophotometric, electroanalytical, and electrophoresis techniques for NRI analysis from pharmaceutical formulations and biological samples. Among all of the published methods, liquid chromatography with UV-vis or MS-MS detection is the most popular technique. The most the common sample preparation techniques in the analytical methods for NRIs include liquid-liquid extraction and solid-phase extraction. Besides the analytical methods for single components, some of the simultaneous determinations are also included in this review.
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    Applications on agricultural and forest waste adsorbents for the removal of lead (II) from contaminated waters
    (Springer, 2012) Saka, Cafer; Şahin, Ömer; Küçük, M.Maşuk
    At present, there is growing interest in using low cost, commercially available materials for the adsorption of heavy metals. The major advantages of adsorption technologies are its effectiveness in reducing the concentration of heavy metal ions to very low levels and the use of inexpensive adsorbent materials. In this review, agricultural and forest waste adsorbents were used to remove Pb2+ ions in wastewater treatment, and their technical feasibilities were reviewed in studies mainly from 2000 to 2010. They all were compared with each other by metal binding capacities, metal removal performances, sorbent dose, optimum pH, temperature, initial concentration and contact time. Although commercial activated carbon is widely used in wastewater treatment applications, it has high costs. The use of agricultural by-products as adsorbent material to purify heavy metal contaminated water has become increasingly popular through the past decade because they are less expensive, biodegradable, abundant and efficient. Instead of activated carbon, this study was focused on the inexpensive materials such as agricultural and forest waste. It was shown that these alternative adsorbents had sufficient binding capacity to remove Pb2+ ions from wastewater.
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    BET, TG-DTG, FT-IR, SEM, iodine number analysis and preparation of activated carbon from acorn shell by chemical activation with ZnCl2
    (Elsevier, 2012) Saka, Cafer
    Activated carbons were produced from acorn shell by chemical activation with zinc chloride (ZnCl2 at 600 degrees C in N-2 atmosphere and their characteristics were investigated. The effects of activation temperature, duration time, impregnation concentration of agent and impregnation time were examined. Adsorption capacity was demonstrated with BET and iodine number. The obtained activated carbons were characterized by measuring their porosities and pore size distributions. BET surface area of the best produced activated carbon was 1289 m(2)/g. The surface chemical characteristics of activated carbons were determined by FT-IR spectroscopic method. The microstructure of the produced activated carbons was examined by scanning electron microscopy (SEM). Thermal gravimetry (TG) and derivative thermal gravimetry (DTG) analysis of produced activated carbon was carried out. (C) 2012 Elsevier B.V. All rights reserved.
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    BET, TG–DTG, FT-IR, SEM, iodine number analysis and preparation of activated carbon from acorn shell by chemical activation with ZnCl2
    (Elsevier, 2012) Saka, Cafer
    Activated carbons were produced from acorn shell by chemical activation with zinc chloride (ZnCl2) at 600 °C in N2 atmosphere and their characteristics were investigated. The effects of activation temperature, duration time, impregnation concentration of agent and impregnation time were examined. Adsorption capacity was demonstrated with BET and iodine number. The obtained activated carbons were characterized by measuring their porosities and pore size distributions. BET surface area of the best produced activated carbon was 1289 m2/g. The surface chemical characteristics of activated carbons were determined by FT-IR spectroscopic method. The microstructure of the produced activated carbons was examined by scanning electron microscopy (SEM). Thermal gravimetry (TG) and derivative thermal gravimetry (DTG) analysis of produced activated carbon was carried out.
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    Bimetallic Co–Ni based complex catalyst for hydrogen production by catalytic hydrolysis of sodium borohydride with an alternative approach
    (Elsevier-Journal of the Energy Institute, 2016) Şahin, Ömer; Kılınç, Dilek; Saka, Cafer
    Hydrogen is a clean energy carrier and is expected to be one of the main energy sources in the 21st century. The basic aim of this study is to develop a feasible new catalyst system for the hydrogen generation by catalytic hydrolysis of NaBH4. The method is an alternative approach for the hydrogen production with metal catalysts. Ni–Co bimetallic complex catalysts with different Co–Ni contents were derived from 4-4'-methylene bis (2,6-diethyl)aniline-3,5-di-tert-butylsalisilaldimin ligand and their catalytic performances were investigated with hydrogen generation by catalytic hydrolysis of NaBH4. Experimental results showed that the Co–Ni contained catalysts exhibited much higher activity than the monometallic complex catalyst. The optimal mixture percentage of Co–Ni complex catalyst was 80:20. It was found that a combination of 2.5 wt% NaBH4 solution concentration and 5 wt% NaOH yields the highest performance for the hydrogen generation. The catalysts were characterized by XRD, FT-IR and SEM techniques.
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    Catalytic activity of cobalt-boron-fluoride particles with different solvent mediums on sodium borohydride hydrolysis for hydrogen generation
    (Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2019) İzgi, Mehmet Sait; Şahin, Ömer; Baytar, Orhan; Saka, Cafer
    Catalysts prepared in a different solvent medium have different activities because of its different acidity, basicity and viscosity properties. The synthesis mechanism of cobalt-boron-fluoride in water, propanol and ethanol solvents was evaluated. Characterization studies of cobalt-boron-fluoride catalyst were performed with Brunauer-Emmett-Teller surface area, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy- energy dispersive x-ray spectroscopy measurements. The effects of sodium borohydride (SB), and temperature on the SB hydrolysis reaction with the catalyst samples were studied. The maximum hydrogen generation rate (HGRs) of the cobalt-boron (ethanol solvent) and cobalt-boron-fluoride (ethanol solvent) catalysts were 1942 and 4533 mlmin−1g−1, respectively. The activation energy was 32.45 kJ mol−1.
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    Characterization of Microwave and Conventional Heating on the Pyrolysis of Pistachio Shells for the Adsorption of Methylene Blue and Iodine
    (Taylor & Francis Inc, 2018) Baytar, Orhan; Sahin, Omer; Saka, Cafer; Agrak, Selman
    The production of activated carbon was investigated using the sequential combination of microwave and conventional heating of pistachio shells as the raw precursor with zinc chloride. Several techniques such as thermogravimetric and differential thermal analyses, infrared spectroscopy, scanning electron microscopy, and specific surface area analyses were performed to characterize the samples. The highest specific surface area value for the activated carbon prepared at a microwave power of 200W with microwave time of 20min, and flow rate of 50mLmin(-1) was 1468m(2)g(-1). The methylene blue and iodine adsorption capacities were 331 and 1276mgg(-1), respectively. The results were compared to those obtained using physical and chemical activation methods and showed that the sequential combination of microwave and conventional heating reasonably influenced the micropore surface area of the samples as well as the specific surface area.
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    Chemical and thermal activation of clay sample for improvement adsorption capacity of methylene blue
    (Taylor & Francis Ltd, 2023) Tegin, Ibrahim; Saka, Cafer
    In this study, the removal of methylene blue (MB) by both raw and modified clay as an abundant, cost-effective was investigated. The modification of the raw clay was done by calcination, acid treatment, and again second calcination processes. In addition, the effects of calcination temperature and acid/base concentration on the adsorption capacity of clay were investigated. The characterisation of clay was performed by scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR) analyzes. Langmuir and Freundlich isotherm models were used. The modified clay provided significant improvements in adsorption capacity compared to the raw clay.
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    Chlorella vulgaris microalgae strain modified with zinc chloride as a new support material for hydrogen production from NaBH4 methanolysis using CuB, NiB, and FeB metal catalysts
    (Pergamon-Elsevier Science Ltd, 2020) Saka, Cafer; Kaya, Mustafa; Bekirogullari, Mesut
    This study aims to produce hydrogen (HG) from sodium borohydride (NaBH4) methanolysis using CuB, NiB or FeB catalysts prepared with a different support material including C. vulgaris microalgae strain modified using zinc chloride (CMS-ZnCl2). The NaBH4 concentration, metal percentage in the supported-catalyst, the optimal ZnCl2 percentage, and temperature effect on the NaBH4 methanolysis were investigated. X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and Scanning electron microscopy (SEM) analysis were performed for the CMS-ZnCl2-CuB characterization. Also, the low activation energy (Ea) of 22.71 kJ mol(-1) was found with the supported catalyst obtained. Under the same conditions, nearly 100% conversion was achieved in the reusability experiments repeated five times, but a gradual decrease in catalytic activity was observed after each use. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Chromatographic Methods for Determination of Drugs Used in Prostate Cancer in Biological and Pharmacological Samples
    (Taylor & Francis Inc, 2019) Saka, Cafer
    Prostate cancer is the second most common cancer and the fifth leading cause of cancer deaths in men worldwide. This review article contains a summary of analyzes performed by chromatographic methods used for the determination of abiraterone acetate, bicalutamide, cabazitaxel, docetaxel, enzalutamide, flutamide, goserelin acetate, leuprolide acetate, and mitoxantrone hydrochloride drugs used in prostate cancer applications in biological and pharmacological samples. In this review, sample preparation procedures, chromatographic procedures, and detectors used for analytical determinations of these drugs are discussed.
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    Co-B-F ve Co-B-P KATALİZÖRLERİ KULLANILARAK NaBH4'DEN HİDROJEN ÜRETİMİNE NaOH'İN ETKİSİ
    (2016) İzgi, Mehmet Sait; Ödemiş, Ömer; Şahin, Ömer; Saka, Cafer
    Bu çalışmada sodyum borhidrürün hidrolizi ile hidrojen üretimi için Co-B-P ve Co-B-F katalizörleri sentezlenmiştir. Sodyum borhidrürden hidrojen üretiminde stabiliteyi sağlamak amacıyla kullanılan sodyum hidroksit konsantrasyonu oldukça önem arz etmekte zira fazla kullanılması durumunda katalizörün katalitik aktivitesini azaltırken, az kullanılması ya da hiç kullanılmaması durumunda ise sodyum borhidrürün kendiliğinden bozunması gerçekleşmektedir. Bu nedenle sentezlenen Co-B-F ve Co-B-P katalizörlerinin sodyum borhidrürün hidrolizinde kullanılması durumundaki optimum sodyum hidroksit konsantrasyonları belirlenmiştir. Farklı sodyum hidroksit konsantrasyonları varlığında reaksiyon hızlarına etkileri ve reaksiyon hız sabitlerine etkileri ayrı ayrı belirlenerek sodyum hidroksit konsantrasyonunun sodyum borhidrürün hidrolizi ile hidrojen üretimi üzerinde ne kadar etkin ve önemli olduğu belirlenmiştir. Co-B-F katalizörü için hidrojen üretim hızı %2,5 NaOH konsantrasyonu varlığında 2400 ml/dk.katalizör, Co-B-P katalizörü için ise 1605 mL/dk.katalizör olarak belirlenmiştir.
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    CoB doped acid modified zeolite catalyst for enhanced hydrogen release from sodium borohydride hydrolysis
    (Pergamon-Elsevier Science Ltd, 2020) Saka, Cafer; Eygi, Mustafa Salih; Balbay, Asim
    Cobalt-boron (CoB) catalyst supported on zeolite modified with hydrochloric acid (CoB-zeolite-HCl) and zeolite modified with acetic acid (CoB-zeolite-CH3COOH) is prepared for the hydrogen (H-2) release from sodium borohydride (NaBH4). The supported catalyst samples were characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscope (SEM), Fourier transforms infrared spectroscopy (FTIR), nitrogen adsorption and, inductively coupled plasma optical emission spectroscopy (ICP-OES). The effects of Co metal loading, NaBH4 concentration, NaOH concentration, temperature, and reusability on the catalytic performance of the CoB-zeolite-HCl catalyst were investigated. The completion time of the reaction using the raw zeolite supported CoB catalyst was about 265 min. However, the completion time of the reaction using the CoB-zeolite-HCl catalyst was decreased to about 80 min. BET surface area values showed that there is a 7-fold increase in the specific surface area for the zeolite activated with HCl compared to the BET surface area for the raw zeolite. The activation energy (Ea) of the catalyzed reaction was 42.45 kJ mol(-1). (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Cobalt loaded organic acid modified kaolin clay for the enhanced catalytic activity of hydrogen release via hydrolysis of sodium borohydride
    (Pergamon-Elsevier Science Ltd, 2021) Saka, Cafer; Eygi, Mustafa Salih; Balbay, Asimm
    Inorganic acids such as hydrochloric acid (HCl), nitric acid (HNO3) and sulphuric acid (H2SO4) are generally used in the acid modification of clays. Here, CoB catalyst was synthesized on the acetic acid-activated kaolin support material (CH3COOH -kaolin- CoB) with an alternative approach. This prepared catalyst, firstly, was used to catalyze the hydrolysis of NaBH4 (NaBH4-HR). The structure of the raw kaolin, kaolin-CH3COOH, and CH3COOH-kaolin-CoB samples were characterized by X-ray diffraction spectroscopy (XRD), Fourier transforms infrared spectroscopy (FTIR), scanning electron microscope (SEM), and nitrogen adsorption. At the same time, this catalyst performance was examined by Co loading, NaBH4 concentration, NaOH concentration, temperature and reusability parameters. The end times of this hydrolysis reaction using raw kaolin-CoB and CH3COOH-kaolin-CoB were found to be approximately 140 and 245 min, respectively. The maximum hydrogen generation rates (HGRs) obtained at temperatures 30 degrees C and 50 degrees C were 1533 and 3400 mL/min/g(catalyst), respectively. At the same time, the activation energy was found to be 49.41 kJ/mol. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Cold plasma and microwave radiation applications for surface modification on the pistachio husk-based adsorbent and its effects on the adsorption of rhodamine B
    (Taylor & Francis Inc, 2016) Saka, Cafer; Sahin, Omer; Kutluay, Sinan
    In this study, cold plasma and microwave radiation technologies were applied on the surface of pistachio husk adsorbent to improve the removal of rhodamine B. The surface properties of pistachio husk, modified by nitrogen gas, were investigated with scanning electron microscopy, Fourier transform infrared spectroscopy, and point of zero charge measurements. The changes of the surface property before and after plasma and microwave radiation treatment were discussed. According to scanning electron microscopy measurement, the surface roughness was increased after plasma and microwave radiation treatment. The removal percentages of rhodamine B compared with untreated pistachio husk were increased from 21.46% to 41.86 and 39.63% (about 100% increase) after modification by cold plasma and microwave radiation treatments, respectively. An increasing in the surface basic groups was observed during the modification according to point of zero charge measurements.
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    Cold plasma and microwave radiation applications on almond shell surface and its effects on the adsorption of Eriochrome Black T
    (Elsevier-Journal of Industrial and Engineering Chemistry, 2013) Şahin, Ömer; Saka, Cafer; Kutluay, Sinan
    Almond shell based adsorbents were thermally modified by cold plasma and microwave radiation for improving adsorption ability of Eriochrome Black T. The maximum adsorption capacities were 6.02, 18.18, and 29.41 mg/g for untreated, cold plasma and microwave radiation treated almond shell, respectively. The removal percentages of EBT compared with untreated almond shell were increased from 39.96% to 81.46% and 84.31% after modification by cold plasma and microwave radiation treatments, respectively. SEM, FT-IR spectroscopy and point of zero charge measurement were applied to analysis the almond shell surface. Data on equilibrium were evaluated by using Langmuir and Freundlich models.
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    Determination of Serotonin-Norepinephrine Reuptake Inhibitor Antidepressants in Pharmaceuticals and Biological Material
    (Taylor & Francis Inc, 2013) Saka, Cafer; Sahin, Omer
    Serotonin-norepinephrine reuptake inhibitors (SNRIs) are a newer form of antidepressant drugs. SNRIs include desvenlafaxine, duloxetine, milnacipran, venlafaxine, and sibutramine. The present study covers the analytical research on SNRIs and their main metabolites, focusing on bioanalytical and pharmaceutical applications. These analytical methods are generally chromatographic, electroanalytical, spectrometric, and electrophoretic methods.