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Öğe Effect of Reduction Temperature and Time on The Reduction of Graphene Oxide with White Cabbage Extract(2021) Kütük, Nurşah; Gürer, Sevil ÇetinkayaGraphene is an important material that has attracted attention in recent years due to its large surface area, mechanical strength, thermal, electrical and magnetic properties. In this work, reduced graphene oxide (RGO) was obtained by reducing the graphene oxide (GO) with green synthesis. For this purpose, white cabbage aqueous extract was selected to reduce GO. The total phenolic acids, which are the reducing agent in the extract, were determined according to the Folin-Cioceltau method. It was determined that there is 0.064 grams of polyphenols in 1 mL of white cabbage extract. In order to determine the reduction experimental conditions, a reduction temperature of 25, 50 and 100 ?C and 1, 2, 4 and 6 hours of reduction time were studied. Structural characterization of synthesized RGOs was performed with XRD, FTIR and SEM techniques. The results showed that GO was reduced at a reduction reaction temperature of 100 °C and a reduction reaction time of 6 hours. The peak seen at 22.08? in the XRD data is evidence of reduction of GO.Öğe EFFECT OF THE SYNTHESIS TEMPERATURE OF POLYCARBOXYLATE-BASED SUPERPLASTICIZER ON THE PERFORMANCE OF CONCRETE(2019) Özduran, Melih; Haste, Zeynep Özserçe; Gürer, Sevil ÇetinkayaGood quality Polycarboxylate superplasticizers (PCEs) production is increasingly important due to development of theconstruction industry in the world. In this study, modified PCEs were synthesized via free-radical polymerization of TranslatedPolyethylene Glycol (TPEG), Thioglycolic Acid (TGA) and Acrylic Acid (AA), in the presence of initiator and chain transferagent according to molecular structure design principle in different initiatory temperatures (40 and 60 ${}^oC$). The effects of PCEssynthesized at different temperatures on the concrete such as water cutting, workability and compressive strength of 7 and 28 days’have been examined. Fourier transform infrared spectroscopy (FTIR) was used for structural characterization.Öğe GREEN REDUCTION OF GRAPHENE OXIDE BY USING KOMBUCHA TEA(2019) Kütük, Nurşah; Boran, Filiz; Gürer, Sevil ÇetinkayaIn this study, a simple and efficient method of reduction for the preparation of reduced graphene oxide (RGO) from grapheneoxide (GO) using Kombucha Tea (KT) is reported. The graphene oxides (GOs) were produced from natural graphite (Gr)powders based on Hummers’ method. KT was used as natural reductants to reduction of GO. Polyphenol content of KT wasdetermined by using Folin-Cioceltau method. KT and GO were mixed in certain ratios to reduce graphene oxide (RGO) atroom temperature. RGO was characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and FourerTransform Infrared (FTIR). It was clearly observed that the functional groups containing oxygen were reduced as a result ofthe analyzes.Öğe OPTIMAL TEMPERATURE CONTROL IN A BATCH POLYMERIZATION REACTOR USING DEADBEAT CONTROL(2019) Gürer, Sevil Çetinkaya; Anaklı, Duygu; Hapoğlu, HaleIn this study, Deadbeat control of a jacketed batch reactor in which styrene polymerization occurs under isothermal conditionshas been investigated experimentally and by simulation to achieve a specific constant number average chain length andconversion in a minimum time. It was founded that Deadbeat control provided a good performance in maintaining the reactortemperature at its set point at the isothermal conditions. It is obtained that desired final conversion and number average chainlength values were almost achieved.Öğe Poli(sodyum 4-stiren sülfonat) Kaplı $SnO_2$ Nanoparçacıklarının Sentezi, Karakterizasyonu ve Gaz Algılama Özelliklerinin İncelenmesi(2019) Boran, Filiz; Taşkıran, İmren; Gürer, Sevil ÇetinkayaBu çalışmada, poli(etilen glikol)(PEG)-Kalay Oksit/poli(sodyum 4-stiren sülfonat) PEG-$SnO_2$/PSS nanokompozitleri, 2 saat boyuncadimetil formamid (DMF) varlığında hidrotermal işlemle hazırlandı. Bunun için yüzey aktif madde PEG ile birlikte daha öncedensentezlenmiş olan 16,4 nm büyüklüğündeki $SnO_2$ nanoparçacıkları kullanıldı. PEG-SnO2/PSS nanokompoziti, PSS ve PEG-$SnO_2$ ilebirlikte DMF varlığında 0°C reaksiyon sıcaklığında 2 saat sürede sentezlendi. Hazırlanan PEG-SnO2/PSS nanokompozitinin yapısal veelementel analizi, taramalı elektron mikrokopisi (SEM), Enerji Dağılım X-Işınları Spektrometresi (EDS), X-ışını difraksiyonu (XRD)ve Fourier transform infrared (FTIR) spektroskopisi teknikleri ile yapıldı. FTIR ve XRD analizleri $SnO_2$ nanoparçacıklarının PSSpolimer yapısına katıldığını gösterirken, SEM ve EDS analizleri$SnO_2$nanoparçacıklarının morfolojik yapısının, PSS ile kompozitlerihazırlandığında PSS polimeri ile kapsüllenerek nanoyapıdan mikroküre yapılara dönüştüğünü gösterdi. Ayrıca, sonuçlar, PEG-$SnO_2$yüzeyinin, güçlü ?-? etkileşimleri altında PSS ile % 39,53'lük bir kapsülleme oranı ile kaplandığını gösterdi. Bu örneklerin amonyak,etanol, aseton, formaldehit ve kloroform gibi uçucu organik bileşen (VOC) buharlarına karşı gaz duyarlılıkları, oda sıcaklığında, ikiprobe tekniği ile elektrometre kullanılarak incelendi. PEG-$SnO_2$ nanoparçacıklarının etanol gazı için yüksek algılama performansısergilediği görüldü. Saf olarak kullanılan PSS, VOC gazlarının hepsine karşı yüksek oranda duyarlılık gösterdi. Deney sonuçlarına göre,PSS ile kapsüllenen PEG-$SnO_2$ nanokompozitinin gaz sensörü malzemesi olarak kullanım potansiyelinin arttırılabildiği söylenebilir.Öğe Reduction of Graphene Oxide using purple cabbage extract and investigation of photocatalytic activity by oxidation(Gazi Universitesi, 2023) Kütük, Nurşah; Boran, Filiz; Gürer, Sevil ÇetinkayaGraphene and its derivatives are an important material with many unique properties and potential in photocatalytic degradation and adsorption applications. Removal of oxygen-containing functional groups by reduction of graphene oxide (GO) is an interesting method that has been used frequently in recent years. The aim of this study is to examine graphene oxide reduction by using green synthesis and purple cabbage aqueous extraxt, which is an easy and effective method, and its use in photocatalytic removal applications. To optimize the synthesis conditions, the reaction temperature was first studied at 25, 50, and 100?, and then the reaction time was studied for 1, 2, 4, and 6 hours. According to XRD, FTIR, UV/vis and SEM results, suitable experimental conditions for GO reduction are obtained at reaction temperature of 100? and reaction time of 6 h. The obtained reduced graphene oxide (IGO) was used in photocatalytic degradation experiments in the aqueous solution of methylene blue (MM), an organic and cationic dye, under UV lamp and in the presence of H2O2. The results showed that after 120 min, IGO removed 85% of MM from the aqueous solution. It was determined that the MM photocatalytic degradation reaction kinetics of IGO matched the pseudo second-order reaction kinetics. © 2023 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved.
