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    Biosorption of dye crystal violet on Tragopogon sp. leaf powder: Equilibrium, kinetics, thermodynamics, and DFT calculations
    (Elsevier, 2024) Eyupoglu, Volkan; Aksu, Aysun; Cetinkaya, Huseyin Fatih; Cetintas, Halil Ibrahim; Cetinkaya, Serap; Tuzun, Burak
    Crystal violet, CV, was adsorbed on dead mass of Tragopogon sp. in aqueous solutions and the adsorption process was evaluated by analytical, visual, and theoretical means. The functional groups on the biosorbent surface were detected by FT-IR (Fourier Transform Infrared Spectrophotometry), and the surface morphology was visualized by SEM (Scanning Electron Microscopy), and EDX (Energy Dispersive X-Ray Analysis). Some of the biosorption conditions, pH, time, adsorbent mass, and temperature, were optimized. Three isotherm models, Langmuir, Freundlich, and Dubinin-Radushkevich, employed for the understanding of the reaction kinetics, suggested a spontaneous endothermic reaction that took place on the surface of Tragopogon sp cells. Iterative usability experiments, involving four biosorption-desorption rounds, showed that Tragopogon sp. biomass retained approximately 42% of its sorbent activity. Calculations, using the Gaussian software packages B3LYP, HF, and M06-2x, indicated a very high biosorption capacity of Tragopogon sp. for crystal violet. Crystal violet had -7.2067 HOMO and 0.1921 LUMO values.
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    Illumination of biosorption of Allura Red on Rhus coriaria L. (sumac) plant: equilibrium, kinetic, thermodynamic, and density functional theory-based analyses
    (Springer Heidelberg, 2024) Caylak, Osman; Cetintas, Halil Ibrahim; Celik, Muhammed Safa; Kaya, Nurevsan; Cetinkaya, Serap; Maslov, Mikhail M.; Kaya, Savas
    In the present paper, the biosorption capability of Rhus coriaria L. (sumac) plant for the effective removal of Allura Red (AR) dye from wastewater was tested in the light of theoretical and experimental tools. The reactive functional groups in the structure of the studied biosorbent and the surface morphology of the mentioned biosorbent were highlighted with the help of FTIR spectrophotometer, SEM (scanning electron microscopy), and EDX (energy-dispersive X-ray analysis). The effect of important parameters such as pH, time, adsorbent mass, and temperature on the biosorption process was checked and discussed in detail. pH 2 was determined as the optimum value for the highest biosorption. Maximum effectiveness was reached at a biosorbent mass of 200 mg. The biosorption process adhered to the Langmuir isotherm and PSO kinetic models, and the process was determined to have a spontaneous and exothermic nature. Through the recovery experiments, it was noted that the studied plant retained approximately 30% of its biosorption capacity after three cycles. To prove the power of the interaction between Allura Red dye and dominant components of Rhus coriaria L. (sumac), density functional theory calculations were performed. Theoretically obtained conceptual DFT-based descriptors, the comments made within the framework of popular electronic structure rules, and calculated adsorption energies were in good agreement with the experimentally obtained data. As a result, it was reported that Rhus coriaria L. can be used as an effective and useful biosorbent for the removal of AR from wastewater.
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    Synthesis and characterization of ?-cyclodextrin polymers and its performance as a drug carrier
    (Taylor & Francis Inc, 2024) Salgin, Sema; Cetintas, Halil Ibrahim; Salgin, Ugur
    The aim of this study was to determine the optimal reaction conditions for the synthesis of hyperbranched cyclodextrin polymer (CDP) and to investigate their performance as drug carriers. In this study, beta-Cyclodextrin (beta-CD) was used as the basis for CDP nanocarriers, which were synthesized by reacting beta-CD with pyromellitic dianhydride (PMDA) as a crosslinking agent. The effects of beta-CD/PMDA molar ratio and reaction time were investigated to optimize the synthesis of CDP. The optimal reaction conditions were determined to be a reaction time of 2 h and a molar ratio of 1/12 beta-CD/PMDA. Ketoprofen (KP) was used as a model drug to evaluate the loading capacity of CDP. The effects of KP/CDP (w/w) loading ratio, temperature, and stirring speed on the formation of the KP/CDP inclusion complex were investigated. The optimum conditions for loading KP into CDP were found to be 1/4 KP/CDP ratio, 4 h, 35 degrees C, and 300 rpm with a loading efficiency of 39.57%. Characterization of the CDP was performed using Zetasizer, FTIR, DSC, SEM and XRD analysis.
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    Synthesis, optimization, and characterization of β-cyclodextrin-based biological metal-organic frameworks as drug carriers
    (Springer Int Publ Ag, 2025) Cetintas, Halil Ibrahim; Salgin, Sema; Salgin, Ugur
    In this study, beta-cyclodextrin (beta-CD)-based metal-organic frameworks (MOFs) were synthesized using the vapor diffusion method, a cost-effective and straightforward approach, to evaluate their potential as drug delivery systems. Ketoprofen (KP), a poorly water-soluble nonsteroidal anti-inflammatory drug (NSAID), was used as a model drug. The effects of reaction time, temperature, ligand-to-metal salt molar ratio and cetrimonium bromide (CTAB) surfactant addition on the properties of beta-CD-Bio-MOFs were systematically investigated. Optimal synthesis conditions-1 day, 30 degrees C, and a 1:4 beta-CD:KOH molar ratio-produced quadrilateral crystals averaging 10-20 mu m in size. Using KCl as the metal source yielded uniform crystals (10-40 mu m), whereas NaOH and FeCl3 did not result in consistent structures. Adding CTAB as a surfactant further reduced crystal sizes to 5-20 mu m. Also, KP loading experiments were conducted to optimize parameters such as temperature, agitation speed, loading time, solvent medium, and mass ratio for achieving maximum loading efficiency. The optimal conditions were determined to be 25 degrees C, 200 rpm, and 3 h in ethanol. Under these conditions, loading efficiencies of 13.4%, 9.6%, and 15.8% were achieved for beta-CD-Bio-MOF, KCl-beta-CD-Bio-MOF, and CTAB-beta-CD-Bio-MOF samples, respectively, with corresponding surface areas of 11.8, 9.7, and 18.4 m2 g-1. In comparison, pure beta-CD, with a specific surface area below 5 m2 g(-)1, exhibited a lower loading efficiency of 4.1%.