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Öğe Alkaline activation synthesis by graphite/calcite mortar and the effect of experimental conditions on compressive strength(Springer, 2023) Kutuk, Nursah; Gurer, Sevil CetinkayaThe construction industry is an application area that has continuity all over the world and requires cheap, durable, and environmentally friendly materials. Synthesis with alkali activation includes materials that have come to the fore in the construction industry in recent years. In this study using alkali activation method, a graphite/calcite mortar was prepared by optimizing the experimental conditions and its properties were investigated. The effects of Na2SiO3/NaOH mass ratio, NaOH solution concentration, and graphite content variables on structure and compressive strength in alkaline activation synthesis were investigated. It was determined that the samples reached a compressive strength of 21 MPa at the end of 28 days when the Na2SiO3/NaOH ratio was 2 and the NaOH concentration was 10 M. In the continuation of the optimized experimental conditions, the effect of the amount of graphite on the compressive strength was examined between 5 and 100% (w/w). Structural properties of the samples were investigated by X-ray diffraction and Fourier transform infrared spectroscopy, and their morphological properties were investigated by scanning electron microscopy. It was determined that C-S-H gel was formed and samples with heterogeneous morphology were synthesized.Öğe Cationic dye biosorption from aqueous solution using sunflower tray and process optimization(Springer Int Publ Ag, 2025) Pek, Irem; Kutuk, Nursah; Dastan, HavanurIn recent years, the level of water resources around the world has been decreasing due to global warming, climate change and increasing consumption. In addition, the developing industry pollutes existing water resources. This situation negatively affects all living things on earth. In this study, the biosorption process of cationic dye methylene blue (MB), which was selected as a model dye compound from residual water, and sunflower tray biosorbent was discussed. It was seen that the amorphous structure of the sunflower tray was similar to the hexagonal structure. The process parameters were investigated to reach the highest biosorption efficiency. The highest efficiency (99%) was achieved at pH 6, biosorbent dose 10 g/L, dye concentration 10 mg/L and temperature 20 degrees C. It was determined that the biosorption process with an exothermic reaction was compatible with the Langmuir isotherm (R2 = 0.96) and the pseudo-second-order (PSO) kinetic model (R2 = 0.99). qmax was calculated as 117.6 mg/g. Delta G values suggested that the interaction between the sunflower tray and MB molecules was not spontaneous.Öğe The Effect of the Plant Age and Growth Period on the Nutritional Substance, Chlorophyll and Steviol Glycoside Rates in Stevia (Stevia Rebaudiana Bertoni) Leaves(TAYLOR & FRANCIS INC, 2018) Ucar, Esra; Ozyigit, Yasar; Eruygur, Nuraniye; Guven, Dilek; Yur, Suleyman; Turgut, Kenan; Ozek, Temel; Kutuk, NursahStevia (Stevia rebaudiana Bertoni) is a perennial and subshrub herb of the Asteraceae family, which originates from South America. Stevia has long been used as a sweetener and herbal medicine throughout the world. The most important feature of stevia is its sweetness with zero calories. This natural feature of Stevia is of utmost importance to everyone, especially those with diabetes and those who diet. In this study, samples were taken from Stevia rebaudiana plants of different ages (2, 3 and 4 years) in different growth periods (H1: 1 July, H2: 1 August, H3: 1 September and H4: 1 October) and an evaluation was made on the nutritional content values, the chlorophyll and sugar rates found in these samples according to the age and growth period of the plant. It was determined that the age of the plant and the harvesting period had an effect on the macro-micro nutritional elements, and chlorophyll and steviol glycoside rates contained in the stevia plant. In addition, as a result of correlation analysis, significant correlations were determined between the parameters measured in the plant. The results of the study demonstrated that in the cultivation of stevia, the best values were obtained from plants that were 3 years old and harvested in July.Öğe Green synthesis of copper oxide nanoparticles using black, green and tarragon tea and investigation of their photocatalytic activity for methylene blue(Pamukkale Univ, 2022) Kutuk, Nursah; Cetinkaya, SevilIn this study, copper oxide nanoparticles (CuO-NPs) were obtained by biosynthesis using aqueous extracts of black tea (BT), green tea (GT) and tarragon tea (TT). The effect of extracts from leaves of plants on the reduction mechanism has been investigated. The amount of polyphenol as using reducing agent in the extracts from the plants was determined according to the Folin-Ciocalteu's method. Total phenolic acid amounts of the extracts of BT, GT and TT were found as 59.18, 42.81 and 49.83 mg/L, respectively. Properties of synthesized CuO-NPs using these extracts were examined by UV-visible spectroscopy, Fourier infrared transformation spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX) and Atomic Force Microscopy (AFM) analysis. In addition, prepared CuO-NPs were used in methylene blue (MB) removal as a photocatalyst. According to AFM results, average size of CuO-NPs was determined ranging from 10 to 12 nm. Regarding photocatalytic activity, prepared CuO-NPs from BT, GT and TT removed 89%, 87% and 90% of dye in 360 min, respectively. In the photocatalytic removal study, the reaction kinetics were investigated with zero, first and second order kinetics.Öğe Green Synthesis of Iron Oxide Nanoparticles Using Black Tea Extract and Investigation of Its Properties(AMER SCIENTIFIC PUBLISHERS, 2018) Cetinkaya, Sevil; Kutuk, NursahIron oxide nanoparticles (FeNPs) were synthesized by green method using black tea (BT) extract as a reducing agent at room temperature. The effect of polyphenol content on the formation of FeNPs was investigated. The morphology of FeNPs could be controlled by changing the amount of BT extract and iron ions. The results showed that size and shape of the nanoparticles depended on the amount of polyphenol content of the mixture. Synthesized iron oxide nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy.Öğe Modeling of Total Phenolic contents in Various Tea samples by Experimental Design Methods(DE GRUYTER POLAND SP ZOO, 2018) Eruygur, Nuraniye; Dincel, Nazire Gulsah Kutuk; Kutuk, NursahTea, from the old ages to the day, is widely consumed both for enjoyment and health care due to its positive effects. The consumption of these products is increasing day by day as a result of the clear presentation of the fact that tea contains high amount of antioxidant substances (such as phenolic compounds), which is important in prevention and treatment of diseases. Tea beverage is a very important source of polyphenols. In this study, phenolic content and antioxidant capacity of different tea species were calculated by modeling with experimental design method. In the experimental part, polyphenol content was determined using the Folin-Ciocalteu method. The total amount of phenolic substance content was examined by Box-Behnken design and response surface method on black tea, green tea and white tea on different extraction temperature, extraction time and solid / liquid ratio. Solid / liquid ratio was found to be the most important parameter in terms of polyphenol content extraction from different tea samples. The highest polyphenol amount (411.762 mg gallic acid / mL) was found in green tea. To the best of our knowledge, this is the first data presenting comparatively study the effect of extraction condition on amounts of phenolic compounds from different tea samples.Öğe Rapid Synthesis of PbO-NPs Photocatalysts, Investigation of Methylene Blue Degradation Kinetics(Gazi Univ, 2023) Gurer, Sevil Cetinkaya; Kutuk, NursahThe study focused on the green synthesis of lead oxide nanoparticles (PbO-NPs) using green tea extract and its use for photocatalytic degradation. The effect of experimental conditions such as green tea extract concentrations and reaction temperatures on the structure and size of PbO-NPs has been investigated. Reaction temperatures of 25, 50 and 85 celcius and green tea extract concentrations of 5, 10, 20, 40, 80 and 100 mg/mL were used for preparing of PbO-NPs. Amount of the phenolic acid contained in the green tea extracts was determined according to the Folin-Cioceltau method. The synthesized PbO-NPs were further confirmed by UV-visible Spectroscopy, Fourier Infrared Transformation Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive (EDX) analysis. Tetragonal and orthorhombic morphology of PbO-NPs were observed in SEM images. While the crystallite structure of the PbO-NPs was obtained for the samples prepared using 5 and 10 mg/mL extract concentration for all reaction temperatures, the amorphous structures of PbO-NPs were seen for the samples prepared using extract concentrations of 20, 40, 80 and 100 mg/mL. Finally, PbO-NPs catalyst was tested for the degradation of methylene blue (MB) under UV light. The effect of dye concentration, catalyst amount and pH on degradation were investigated. By determining suitable experimental conditions, MB degradation reached 89% with PbO-NPs in 60 minutes. The reaction kinetics of MB removal from aqueous solution under UV lamp and in the dark media were compared for first-order and second-order reaction kinetics.Öğe Removal of lead ions (Pb2+) from aqueous solution using chitosan/starch composite material: Experimental and density functional theory findings(Springer Heidelberg, 2024) Celik, Muhammed Safa; Caylak, Osman; Kutuk, Nursah; Yenidunya, Ali Fazil; Cetinkaya, Serap; Maslov, Mikhail M.; Kaya, SavasTreatment of wastewater has become vital to prevent environmental pollution in recent years. Adsorption is an easily applicable, low-cost and efficient method and is the subject of this study. In this study, an adsorbent was synthesized to be used in heavy metal removal using chitosan and starch. The composite was characterized by Fourier transform infrared (FTIR) spectrophotometry, X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis. It was determined that the composite had an amorphous and compact structure. Adsorption experiments were carried out under the optimized parameters such as solution pH, concentration, adsorbent amount, equilibrium time, and temperature. It shows that during adsorption, with the increase in pH, the adsorption efficiency and adsorption capacity first increase and then a fluctuation occurs. The highest adsorption efficiency and Q value were reached at pH 3.46 as 78% and 0.038 mol/kg, respectively. Moreover, the adsorption capacity (Q) reached its highest value with a value of 0.067 mol/kg in the presence of 30 mg adsorbent. Equilibrium experiments were validated by the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. To investigate the adsorption mechanism, pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models were used. It was determined that the adsorption process followed the D-R isotherm (R-2 = 0.99) and PSO (R-2 = 0.99). Therefore, the existence of chemical adsorption can be mentioned. Thermodynamic parameters enthalpy (triangle H), Gibbs free energy (triangle G) and entropy change (triangle S) were investigated. The adsorbate-adsorbent interactions were studied by density functional theory (DFT).Öğe Removal of safranin O from wastewater using Streptomyces griseobrunneus dead biomass and in silico calculations(Springer Heidelberg, 2023) Celik, Muhammed Safa; Kutuk, Nursah; Yenidunya, Ali Fazil; Cetinkaya, Serap; Tuzun, BurakEnvironmental pollution with the dye produced by the textile industry causes a serious problem worldwide. The aim of the study is to use the environmentally friendly and low-cost Streptomyces griseobrunneus (S. griseus S15) dead cells for the adsorption of safranin O from aqueous milieu. Optimum retention was achieved with 200 mg/L safranin O and 25 g/L adsorbent at pH 9. Biosorption was found to better fit the Langmuir isotherm and PSO kinetics. The maximum biosorption (q(max)) was 188.67 mg/g. The reaction between S. griseus S15 and safranin O was chemical, exothermic, and spontaneous. S. griseus S15 biomass was reusable. Molecules supposed to be involved in the process were investigated by using a Gaussian software program, calculations B3LYP, HF, and M06-2X, 6-31G, 6-31++G, and 6-31++G**. For molecular docking calculations, the affinity of safranin O molecule to various proteins was investigated. Finally, ADME/T was applied to gain an insight into the possible effects of safranin O on human health.Öğe Theoretically supported experimental analyses on Safranin O biosorption from textile wastewater via dead biomass of Spirogyra porticalis(Springer Heidelberg, 2024) Aksu, Aysun; Kutuk, Nursah; Caylak, Osman; Kasaka, Erguen; Cetinkaya, Serap; Maslov, Mikhail M.; Kaya, SavasHigh-performance chemical systems designed to eliminate pollution caused by dyestuffs are still among the focuses of interest of chemists. Non-toxic biological materials especially have begun to be widely used in this field. Fourier transform infrared spectrometry, SEM (scanning electron microscopy), EDS (energy-dispersive X-ray analysis), and TGA (thermogravimetric analysis) were performed. Adsorption was performed in batch-adsorption experiments. Optimization processes involved pH, amounts of the sorbent and Safranin O, adsorption kinetics, desorption, and reusability. To highlight the mechanism of the interaction between Safranin O and S. porticalis and to predict the power and nature interactions, density functional theory computations were performed. Optimization processes included pH, amounts of sorbent and Safranin O, adsorption kinetics, desorption, and reusability. Experimental results were re-evaluated using Langmuir and Freundlich isotherm models and the biosorption process followed Freundlich isotherm kinetics. The biosorption mechanism was understood by pseudo-first-order (PFO), intraparticle diffusion (IPD), and Elovich models. Adsorption was determined to follow PFO kinetics: physical, endothermic, and spontaneous. The highest recovery was obtained in NaOH. Density functional theory (DFT) finding calculations were also performed to prove the high adsorption capacity for Safranin O of the material used.Öğe Titan Yellow Biosorption of Hemp Waste in Acidic Medium and Modeling of Experimental Conditions by Multi Gene Genetic Programming(Institute of Electrical and Electronics Engineers Inc., 2022) Arslan, Sibel; Kutuk, NursahIn recent years, pollutants such as dyes, drugs and heavy metals in wastewater have caused serious environmental pollution. In this study, biosorption of titan yellow (TY) using hemp waste was studied. In the biosorption of TY dye to hemp waste, 88 % biosorption was achieved with an initial dye concentration of 10 mg/L and a biosorbent ratio of 2 g/L in acidic medium. When Langmuir and Freundlich isotherms were examined, R^{2} values were obtained as 0.92 and 0.95, respectively. Its maximum biosorption capacity has been calculated as 51.8 mg/g. It has also been observed that the biosorption process adapts to the pseudo second order reaction (R^{2}= {0}.99) kinetics. We have also developed more accurate and reliable correlation models using Multi-Gene Genetic Programming (MGGP), a powerful method based on evolutionary computation. The performance of the developed models was examined using three statistical criteria. A comparison of the criteria reveals that MGGP is effective in simulating the biosorption process in the real world. © 2022 IEEE.
