Yazar "Gurdal, Savas" seçeneğine göre listele

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    Biological and Nutritional Applications of Microalgae
    (Mdpi, 2025) Saritas, Sumeyye; Kalkan, Arda Erkan; Yilmaz, Kadir; Gurdal, Savas; Goksan, Tolga; Witkowska, Anna Maria; Lombardo, Mauro
    Microalgae are photosynthetic microorganisms that have a rapid growth cycle and carbon fixation ability. They have diverse cellular structures, ranging from prokaryotic cyanobacteria to more complex eukaryotic forms, which enable them to thrive in a variety of environments and support biomass production. They utilize both photosynthesis and heterotrophic pathways, indicating their ecological importance and potential for biotechnological applications. Reproducing primarily through asexual means, microalgae have complex cell cycles that are crucial for their growth and ability to adapt to changing conditions. Additionally, microalgae possess bioactive compounds that make them both nutritious and functional. Thanks to their content of proteins, lipids, carbohydrates, vitamins, and minerals, they play an important role in the development of functional food products, particularly by enhancing nutritional content and product quality. Furthermore, studies have demonstrated that algae and algal bioactive compounds support cardiovascular health, immune function, and gut health, especially in relation to obesity and other metabolic diseases. They also contribute to skin health and cognitive functions, including memory. This review article explores the biological, nutritional, and functional properties of microalgae based on the studies conducted.
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    Dimethyl ether synthesis on clinoptilolite zeolite and HZSM5-based hybrid catalysts in a fixed-bed reactor
    (Pergamon-Elsevier Science Ltd, 2023) Gurdal, Savas; Yasar, Muzaffer
    In this study 4 different acid catalysts were prepared and mixed with commercial CZA catalysts and investigated in direct DME synthesis. Some of the used acid catalysts were not investigated in the literature therefore the work involves novelty. In a fixed-bed reactor, dimethyl ether (DME) was synthesized from the synthesis gas on two catalysts from, natural clinoptilolite and zeolite catalysts. The clinoptilolite (HK and DK) and two (HZSM5(117) and HZSM5(360)) catalysts mixed with commercial CuO/ZnO/Al2O3 (CZN) catalysts. The catalysts were also characterized by analytical chemistry techniques such as XRD, BET, TGA, and FTIR. Four different catalysts (HK, DK, HZSM5(117) and HZSM5(360)) and CZA catalysts were mixed at a ratio of 3/1, respectively, and studies were carried out in a fixed-bed reactor. Four different catalyst composition activity tests were made at tem-peratures 250, 275, and 300 & DEG;C. At the same time, the pressure was 30 and 40 bar and four different times (30, 60, 90, and 120 min). The composition of the gases fed to the system for DME was adjusted to N2/CO2/CO/H2 = 36/10/18/36 by volume. DME selectivity (SDME) and total carbon (XC) conversion were calculated for each condition. The experimental results showed that the highest DME selectivity of 96.50% was observed in the reaction of the DK + CZA catalyst mixture at 250 & DEG;C and 30 min at 40 bar. In addition, high DME selectivity was obtained in all reactions of DK + CZA and HK + CZA catalyst compositions at three different temperatures. The highest DME selectivity obtained is 89.69% for the reaction of the HK + CZA catalyst mixture at 300 & DEG;C and 60 min at 30 bar. Experimental results gave insights into Dimethyl ether synthesis from syngas on clinoptilolite zeolite and HZSM5-based hybrid catalysts in a fixed-bed reactor.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Heavy Oil Residue Upgrading With Iron Based Catalysts Under High Hydrogen Pressure
    (2021) Gurdal, Savas; Yılmaz, Kadir; Akmaz, Solmaz
    In this study, effective and easily accessible cheap catalysts that assist converting heavy oil residue to lighter products with high yield are investigated. Hydrocracking experiments were carried out in a 10 ml stainless steel bomb-type reactor with up and down stirrer at 200 times of reciprocation per minute. The catalyst mixture provided the minimum coke production was investigated. FeSO4.H2O, the binary mixtures of FeSO4.H2O with metal oxides (Fe2O3, Al2O3, CaO, SiO2) and the mixtures Fe2O3, Al2O3 and SiO2 with elementary sulphur were used as catalyst. Experiments were conducted at 425 0C for 90 minutes with the initial pressure 100 bar H2. The amount of coke, liquid products and C5- gas products were calculated for each experiment. Gel Permeation Chromatography (GPC), Nuclear Magnetic Resonance (1H NMR) and elemental analysis were used for Iranian heavy oil residue. Differential Scanning Calorimeter (DSC) was used to analyze the catalyst. According to the results, minimum coke production is achieved by FeSO4.H2O+SiO2 catalyst. Although minimum coke production achieved with FeSO4.H2O+SiO2, middle distillate containing toluene soluble fraction (TSF) was maximized with Fe2O3+Al2O3+Sulphur catalyst mixture. In addition, the product selectivity in the reactions with the least coke formation showed selectivity in the direction of the formation of gas and light products, not in the direction of liquid product formation.
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    High-Efficiency and Fast Hydrogen Production from Sodium Borohydride: The Role of Adipic Acid in Hydrolysis, Methanolysis and Ethanolysis Reactions
    (Mdpi, 2024) Gurdal, Savas
    In this study, hydrogen production through the hydrolysis, ethanolysis, and methanolysis reactions of NaBH4 using adipic acid as a catalyst was investigated for the first time. Adipic acid solutions were prepared with methanol and ethanol at concentrations of 0.1, 0.2, 0.3, 0.4, and 0.5 M. In these reactions, NaBH4-MR (methanolysis) and NaBH4-ER (ethanolysis) reactions were carried out at 30, 40, and 50 degrees C with NaBH4 concentrations of 1.25%, 2.5%, and 5%. Hydrolysis reactions (NaBH4-HR) were conducted at 0.1 M under the same conditions. In the ethanolysis and methanolysis reactions at 30 degrees C, total hydrogen conversion was achieved at 0.3 M, 0.4 M, and 0.5 M. However, in the hydrolysis reactions, total hydrogen production was only obtained at 50 degrees C. It was observed that in the NaBH4-MR and NaBH4-ER reactions, total hydrogen conversion could be achieved within 4-5 s. The utilization of adipic acid as a catalyst for hydrogen production from NaBH4 through ethanolysis and methanolysis reactions is proposed as a highly efficient and fast method, characterized by impressive conversion rates.
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    Kinetic Evaluation and Catalytic Efficiency of Sebacic Acid as a Novel Catalyst in Hydrogen Generation via NaBH4 Alcoholysis Reactions
    (Mdpi, 2024) Gurdal, Savas
    This study explores the use of sebacic acid, a catalyst not previously examined in the literature, for hydrogen production from NaBH4 through methanolysis and ethanolysis reactions. Solutions of sebacic acid with concentrations ranging from 0.1 M to 0.4 M were prepared and tested. At a concentration of 0.3 M, 90% of the hydrogen from a 0.33 M NaBH4 solution was released within 3 s, and full release was achieved in 4 s. Hydrogen production rates reached 4500 mL/min for ethanolysis and 4845 mL/min for methanolysis, with methanolysis reactions proving faster. The activation energies for methanolysis and ethanolysis were calculated as 7.17 kJ/mol and 52.3 kJ/mol, respectively. These results demonstrate that sebacic acid enables rapid and efficient hydrogen production, offering a new approach that significantly advances current hydrogen production methods.
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    Optimization of bioethanol production from sugar beet processing by-product molasses using response surface methodology
    (Springer Heidelberg, 2024) Altinisik, Sinem; Nigiz, Filiz Ugur; Gurdal, Savas; Yilmaz, Kadir; Tuncel, Necati Baris; Koyuncu, Sermet
    Bioethanol production from renewable biomass sources has garnered significant interest due to its potential as a sustainable alternative to fossil fuels. In this study, we investigated the optimization of bioethanol production from molasses, a by-product of the sugar production process using Saccharomyces cerevisiae through Response Surface Methodology (RSM). Initially, the fermentation process was optimized using RSM, considering four independent variables: substrate concentration, pH, temperature, and fermentation time. Subsequently, the effects of these variables on bioethanol yield were evaluated, and a quadratic model was developed to predict the optimum conditions. Analysis of variance (ANOVA) indicated a high coefficient of determination (R2) for the model, suggesting its adequacy for prediction. The optimized conditions for bioethanol production were determined as follows: substrate concentration of 200 g L-1, pH of 5.0, temperature of 30 degrees C and fermentation time of 72 h. Under these conditions, the predicted bioethanol yield was 84%. Overall, this study demonstrates the successful application of RSM for optimizing bioethanol production from molasses using S. cerevisiae, highlighting its potential as a promising feedstock for biofuel production.