Browsing by Author "Yilmaz, Selehattin"

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Adsorption of Uranium (Vi) From Aqueous Solutions Using Boron Nitride/Polyindole Composite Adsorbent
(Wiley, 2024) Emre, Deniz; Zorer, Ozlem Selcuk; Bilici, Ali; Budak, Erhan; Yilmaz, Selehattin; Kilic, Necla Caliskan; Sogut, Eda Gokirmak
Turbostratic boron nitride (tBN) surface is modified with polyindole (PIn) by a facile polymerization technique and the uranyl adsorption efficiency of this mesoporous hybrid is investigated. The successful surface modification is confirmed by FT-IR, Raman, XRD, TEM, SEM, EDX, EDS mapping XPS, BET, and zeta potential techniques. The batch experiments are performed in various temperatures (T), contact times (t), pH, and initial solution concentrations (C-0) to evaluate its adsorption performance. The optimum adsorption performance is achieved at pH = 5.0-5.5, T = 307 K, t = 10 min, C-0 = 18 mg L-1. These experimental results are evaluated using Freundlich, Redlich-Peterson, and Langmuir isotherm models, which presents equivalent regression coefficients. Maximum adsorption capacity (q(m)) of the nanoadsorbent (tBN/PIn), determined by the Langmuir isotherm, is 315.29 mg g(-1). The adsorption kinetics of uranyl ions on tBN/PIn are in harmony with the pseudo-second order model. tBN/PIn nanoadsorbent provides high adsorption efficiency even at exceptionally low UO22+ concentration range (4-40 mg L-1) and low adsorbent mass (0.005 g). XPS analysis results show that 0.05% of uranium is adsorbed on tBN/PIn via mainly U-O coordination. The results of present study demonstrate that tBN/PIn can a potential adsorbent for removing uranium from aqueous solutions.
Chemical Composition, Antimicrobial, Antioxidant and Anthocyanin Activities of Mosses (Cinclidotus Fontinaloides (Hedw.) P.beauv. and Palustriella Commutata (Hedw.) Ochyra) Gathered From Turkey
(Taylor & Francis Ltd, 2017) Yayintas, Ozlem Tonguc; Alpaslan, Duygu; Yuceer, Yonca Karagul; Yilmaz, Selehattin; Sahiner, Nurettin
Cinclidotus fontinaloides (Hedw.) P. Beauv. and Palustriella commutata (Hedw.) Ochyra were used in this study. The chemical composition of mosses in the ethanol and water extract was determined using GC-MS and FT-IR. Antioxidant activities of moss extracts were tested by total phenol and ABTS methods. Trolox equivalent value (TEAC) of mosses was calculated as 26 +/- 0.32 and 10 +/- 0.22 mg/g. The amounts of the flavonoid compounds were calculated as mg gallic acid. Gallic acid equivalent value of mosses was calculated as 587 +/- 0.55 and 496 +/- 0.22 mg/g. The extracts antimicrobial activity was tested against Escherichia coli (ATCC 8739), Bacillus subtilis (ATCC 6633), Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (ATCC 10145) and Candida albicans (ATCC 10231). Significant antibacterial effect was observed for C. fontinaloides and P. commutata in ethanol extract. Total anthocyanin activities of C. fontinaloides and P. commutata were determined as 50 +/- 0.17 and 144 +/- 0.33 mg/L. [GRAPHICS] .
Porous Graphitic Carbon Nitride Nanosheets Coated With Polyfluorene for Removal of Malachite Green and Methylene Blue Dyes and Cu (Ii) Ions
(Elsevier Science Sa, 2022) Sogut, Eda Gokirmak; Emre, Deniz; Bilici, Ali; Kilic, Necla Caliskan; Yilmaz, Selehattin
Dyes and heavy metal ions are of great interest for environmental studies as they are common pollutants in industrial applications. Therefore, development of innovative adsorbents has received tremendous interest in wastewater treatment studies. In this study, a new hybrid adsorbent (g-C3N4/AFP) was prepared by modifying porous graphitic carbon nitride surface (g-C3N4) with 2-amino fluorene polymer (AFP) and investigated its adsorptive behaviour for removal of representative dyes and heavy metal from aqueous solution. Experimental data obtained from batch tests were analysed using two parameters (Freundlich, Langmuir and Dubi-nin-Radushkevich) and three parameters (Sips) isotherm models. Langmuir isotherms were the best model to describe the experimental results of Methylene blue (MB) and Malachite green (MG) dye adsorptions, while Freundlich isotherms were the best for Cu (II) ions. Sips isotherm model was found to have the highest regression coefficient (>= 0.99) among the two-parameters isotherms studied. The maximum adsorption capacities of g-C3N4 and g-C3N4/AFP were found to be 226.88 and 327.83 for MG, 85.73 and 221.85 for MB and 184.51 and 452.19 mg g(-1) for Cu (II), respectively. This increase in adsorption capacity can be explained by the improved textural properties of the new hybrid adsorbent and the presence of multiple functional groups in its structure. A possible adsorption mechanism was suggested using FTIR and pH(pzc) data.
Quantitative Clinical Diagnostic Analysis of Acetone in Human Blood by Hplc: a Metabolomic Search for Acetone as Indicator
(Hindawi Ltd, 2016) Kalkan, Esin Akgul; Sahiner, Mehtap; Cakir, Dilek Ulker; Alpaslan, Duygu; Yilmaz, Selehattin
Using high-performance liquid chromatography (HPLC) and 2,4-dinitrophenylhydrazine (2,4-DNPH) as a derivatizing reagent, an analytical method was developed for the quantitative determination of acetone in human blood. The determination was carried out at 365 nm using an ultraviolet-visible (UV-Vis) diode array detector (DAD). For acetone as its 2,4-dinitrophenylhydrazone derivative, a good separation was achieved with a ThermoAcclaim C-18 column (15 cm x 4.6mm x 3 mu m) at retention time (t(R)) 12.10 min and flowrate of 1mL min(-1) using a (methanol/acetonitrile) water elution gradient. The methodology is simple, rapid, sensitive, and of low cost, exhibits good reproducibility, and allows the analysis of acetone in biological fluids. A calibration curve was obtained for acetone using its standard solutions in acetonitrile. Quantitative analysis of acetone in human blood was successfully carried out using this calibration graph. The applied method was validated in parameters of linearity, limit of detection and quantification, accuracy, and precision. We also present acetone as a useful tool for the HPLC-based metabolomic investigation of endogenous metabolism and quantitative clinical diagnostic analysis.