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  • Küçük Resim
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    Adsorption of Congo red and malachite green using chitosan derived from blue crab shells
    (Springer, 2025) Özüdoğru, Yeliz; Gönülaçar, Selin; Yüz, Esmanur
    The aim of this work was to evaluate the adsorption capacities of the acidic dye Congo red (CR) and the basic dye malachite green (MG), which are hazardous to the environment and human health in aquatic environments, using chitosan derived from blue crab shells, which are considered waste materials. By first extracting chitin and then chitosan from blue crabs, the maximum adsorption capacities of these dyes in aquatic solutions were investigated. Parameters such as pH, contact time, initial concentration of MG/CR, and temperature were analyzed. Characterization of the adsorbent was performed using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy. The FTIR findings showed that hydrogen bonds and C=O and N-H bending contributed to the adsorption of MG/CR. The equilibrium data were analyzed with Langmuir and Freundlich isotherms, and kinetic models were applied. The highest maximum adsorption capacities were 68 mgg-1 for CR at 25 degrees C and 140 mgg-1 for MG at 45 degrees C. Thermodynamic analysis revealed that MG adsorption was spontaneous and endothermic, whereas CR adsorption was exothermic. These results show that MG dye has a higher adsorption capacity (140 mgg-1) compared to CR (68 mgg-1) using chitosan derived from blue crab shells.
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    Adsorption of Methylene Blue from Aqueous Solution Using Spent Coffee/Chitosan Composite
    (Pleiades Publishing Inc, 2023) Özüdoğru, Yeliz; Tekne, Ecem
    This study aimed to investigate the adsorption of Methylene Blue from aqueous solution using different concentrations of spent coffee/chitosan composite. Adsorption parameters such as pH, contact time, initial Methylene Blue concentration, and temperature were investigated. Characterization of the adsorbent was performed with Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX). The FTIR findings showed that the hydrogen bond is a predominant contributor to the adsorption of MB by absorbed. The equilibrium data were analyzed with Langmuir and Freundlich isotherms, and kinetic models were also applied. The maximum adsorption capacity was noted to increase with an increase in temperature, from 298 to 308 K, but then decreased from 308 to 318 K. The highest maximum adsorption capacities among all coffee/chitosan beds were 75.76 mg g–1 at 298 K, 108.7 mg g–1 at 308 K, and 33.67 mg g–1 at 318 K. These results show that a waste coffee/chitosan composite is a cost-effective, eco-friendly material for removing methylene blue from aqueous solution.
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    Öğe
    Cystoseira Barbata İle Toryum Biyosorpsiyonu
    (2019) Özüdoğru, Yeliz
    Bu çalışmada, Cystoseira barbata’nın biyosorbent olarak kullanılmasıyla, sulu çözeltide bulunan Th(IV) radyoaktif iyonlarının giderilmesine çalışılmıştır. Kesikli ekstraksiyon yöntemi uygulanmış vebiyosorpsiyona pH, süre ve derişim gibi etkileri incelenmiştir. Tutunma miktarının pH değişimindenpek etkilenmediği belirlenmiştir. Süre denemeleri sonucunda ise, biyosorpsiyon işleminin ilk 150dakika içerisinde dengeye ulaştığı görülmüştür. Derişim denemeleri sonucunda elde edilen verilere,Langmuir ve Freundlich izoterm modelleri uygulanmış, qm değeri 39,45 mg/g olarak bulunmuştur.Adsorpsiyon denemeleri sonucunda, adsorpsiyonun Freundlich izoterm modeline daha çok uyduğubelirlenmiştir. Yapılan SEM (Scanning Electron Microscop) ve FTIR (Fourier transformed-infraredspectroscopy) analizleri ile radyoaktif maddenin alg yüzeyinde meydana getirdiği değişikliklergözlenmiş ve Th (IV) radyoaktif iyonlarının alg yüzeyinde hangi gruplara tutunduğu belirlenmiştir.
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    Öğe
    METİLEN MAVİSİNİN MODİFİYE EDİLMİŞ Cystoseira barbata (STACKHOUSE) C. AGARDH KULLANILARAK BİYOSORPSİYONU
    (2017) Özüdoğru, Yeliz; Merdivan, Melek
    Bu çalışmada, sulu çözeltide bulunan metilen mavisi (MM) boyar maddesinin modifiye edilmiş (0,1M HNO3 ve 1M HNO3 ile) Cystoseira barbata kullanılarak giderilmesine çalışılmıştır. Adsorpsiyona, pH'ın, temas süresinin, farklı derişimlerde bulunan MM çözeltisinin etkileri incelenmiştir. Çalışma sonucunda, ilk 50dk. içerisinde sistemin dengeye geldiği ve adsorpsiyon kapasitesinin pH değişiminden pek etkilenmediği gözlemlenmiştir. Yapılan izoterm çalışmalarında ise, Freundlich izoterm modeline daha çok uyduğu belirlenmiş ve qmax değeri 0,1M HNO3 grubunda daha yüksek (100,6mg/g) bulunmuştur. Yapılan SEM ve FTIR analizlerinde ise, MM boyar maddesinin alg yüzeyinde meydana getirdiği değişikler ve alg yüzeyinde hangi gruplara tutunduğu belirlenmiştir
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    Removal of malachite green dye by adsorption onto chitosan-montmorillonite nanocomposite: Kinetic, thermodynamic and equilibrium studies
    (Wiley-V C H Verlag Gmbh, 2025) Çetin, Mert; Özüdoğru, Yeliz
    In this study, the efficiencies of chitosan, montmorillonite, and chitosan/montmorillonite composites in various ratios for the removal of malachite green dye from aqueous solutions were investigated, and their maximum adsorption capacities were compared, and the effects of factors such as composite concentration, pH, contact time, dye concentration, and temperature were examined. Recovery attempts using different chemicals were also performed. Adsorption was analyzed using Langmuir and Freundlich isotherm models, and thermodynamic analyses were conducted. Fourier-transform infrared (FTIR) and scanning electron microscopy (SEM) analyses were used to investigate surface changes. The highest adsorption capacity was found for the 20% chitosan/montmorillonite composite (400 mg g-1). Temperature studies indicated a decrease in adsorption capacity with increasing temperature. Kinetic studies observed that the data fit the pseudo-second-order kinetic model better. In recovery attempts, more than 95% recovery was achieved with HNO3 and HCl. FTIR results showed that chitosan-montmorillonite interactions involved -NH, -OH, C=O, and C-O bonds, while dye binding was mainly through OH bonds. SEM analysis revealed that montmorillonite reduced surface cracks and roughness, creating a more homogeneous structure, and more rough areas appeared after dye binding. As a result, the chitosan/montmorillonite composite significantly enhanced dye adsorption capacity.
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    THE LIVER LIPID FATTY ACID COMPOSITION OF TWO CARTILAGINOUS FISH, THE THORNBACK RAY (Raja clavata) AND THE COMMON SMOOTH-HOUND (Mustelus mustelus)
    (2019) Yığın, Çiğdem Cahide; Çakır, Fikret; Cabbar, Koray; Kızılkaya, Bayram; Ormancı, Hasan Basri; Öztekin, Alkan; Özüdoğru, Yeliz
    We have evaluated the fatty acid composition of the livers from two cartilaginous fish species Rajaclavata (thornback ray) and Mustelus mustelus (common smooth-hound) caught off the NorthernAegean Sea. While there was generally little variation between species, Mustelus mustelus indicated low saturated (SFA) in summer (29.61%), in spring (32.57%), in autumn (30.07%) and inwinter (31.81%) and high polyunsaturated fatty acid (PUFA) in summer (40.35%), in spring(36.50%), in autumn (30.21%) and in winter (27.26%) levels. The dominant fatty acids were palmitic acid (C16:0), oleic acid (C18:1 (n-9)), eicosapentaenoic acid (EPA; C20:5 (n-3)), and docosahexaenoic acid (DHA; C22:6 (n-3)) in both cartilaginous fish species in all seasons. The ratioof DHA/EPA with respect to the total of fatty acids in livers oils was ranged from 2.66% to 4.44%for Mustelus mustelus and 2.89% to 4.46% for Raja clavata. The n:3/n:6 ratio of thornback raywas higher compared to smooth-hound shark in all seasons. The liver oil of R. clavata and M.mustelus represent a valuable source of omega-3 PUFA that can be used for human and animalnutrition.