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Öğe Adsorption of phenolic compounds onto calix[4]arene-bonded silica gels from aqueous solutions(ELSEVIER SCIENCE BV, 2018) Dolaksiz, Yasemin Ekin; Temel, Farabi; Tabakci, MustafaThis article describes the preparation of calix[4]arene-bonded silica gels (C [4] BS and DMC [4] BS), and their application to the removal of some selected phenolic compounds such as phenol (PHE), p-chlorophenol (PCP), m-nitrophenol (MNP) and p-nitrophenol (PNP) from aqueous solutions by adsorption method. In initial adsorption experiments appeared that C [4] BS was much more effective in adsorption of PNP rather than PHE, PCP and MNP, whereas DMC [4] BS exhibited too little adsorption ability towards all phenols. Herein, it was concluded that the hydrogen bonding capacities of both phenols and calix[4]arene based adsorbents played a predominant role in the interactions between adsorbate and adsorbent within the adsorption mechanism. Thus, in subsequent studies, the C [4] BS was employed as an adsorbent in the adsorption of PNP, and adsorption conditions were optimized. Furthermore, isotherm and kinetic studies were performed to clarify the phenomena of PNP adsorption onto C [4] BS.Öğe Calix[4]arene coated QCM sensors for detection of VOC emissions: Methylene chloride sensing studies(ELSEVIER, 2016) Temel, Farabi; Tabakci, MustafaThis paper describes the sensing studies of QCM sensors with coated some calixarene derivatives bearing different functional groups for some selected Volatile Organic Compounds (VOCs) such as acetone, acetonitrile, carbon tetrachloride, chloroform, methylene chloride (MC), N,N-dimethylformamide, 1,4-dioxane, ethanol, ethyl acetate, xylene, methanol, n-hexane and toluene. The initial experiments have revealed that whole the calix[4]arene modified QCM sensors exhibited strongest sensing ability to MC emissions. Thus, the detailed studies were performed for only MC emissions after the determination of relatively more effective calix-coated QCM sensors for MC emissions in aqueous media. The results demonstrated that QCM sensor coated with calix-7 bearing both amino and imidazole groups was most useful sensor for MC emissions with 54.1 ppm of detection limit. Moreover, it was understood that cyclic structures, H-bonding capabilities and also good preorganization properties of calixarene derivatives played an important role in VOC sensing processes. (C) 2016 Elsevier B.V. All rights reserved.Öğe A highly selective fluorescent sensor based on calix[4]arene appended benzothiazole units for Cu2+, S2- and HSO4- ions in aqueous solution(ELSEVIER SCIENCE SA, 2016) Erdemir, Serkan; Tabakci, Begum; Tabakci, MustafaA novel calix[4]arene receptor containing benzothiazole units in 1,3-alternate conformation (L) was synthesized and characterized by H-1, C-13, APT, COSY NMR, FTIR, elemental analysis, and UV-vis spectral data. The cation and anion binding properties of L were investigated in the presence of various cations and anions. L showed "on-off' type fluorescence response towards Cu2+ with high selectivity in aqueous solution (CH3CN/H2O, 4/1, v/v). Once binding with Cu2+, L-Cu2+ complex displayed high selectivity for sulfide. Among the various anions, only sulfide anion induced the revival of fluorescence of L, resulting in "off-on" type sensing of sulfide anion. Furthermore, L served exclusive response towards HSO4- ion via hydrolysis process with 10-fold fluorescence enhancement at 542 nm. (C) 2016 Elsevier B.V. All rights reserved.Öğe Immobilization of calix[6]arene bearing carboxylic acid and amide groups on aminopropyl silica gel and its sorption properties for Cr(VI)(SPRINGER, 2008) Tabakci, MustafaAn aminopropyl silica gel-immobilized calix[6]arene (C[6]APS) containing both amide and acid moieties was prepared from p-tert-butylcalix[6]arene hexacarboxylate derivative and aminopropyl silica gel in the presence of N,N'-diisopropyl carbodiimide coupling reagent. C[6]APS was used to evaluate the sorption properties of Cr(VI) as a sorbent material. In sorption studies, it was observed that C[6]APS was highly effective at pH 1.5 for Cr(VI). The effect of parameters such as pH, sorbent dosage, contact time, initial Cr(VI) concentration and temperature on Cr(VI) sorption; the sorption isotherms were also studied. Maximum sorption capacity was obtained as 3.1 mg g(-1) at pH 1.5 and 25 C for 1 h and 10.4 mg L-1 initial Cr(VI) concentration. Thermodynamic parameters such as change in free energy, enthalpy, and entropy were also determined. In the isotherm studies, Langmuir and Freundlich isotherm models were applied and it was found that the experimental data confirmed to Freundlich isotherm model, and the batch sorption capacity of C[6]APS was calculated as 37.66 mg g(-1).Öğe New diamino derivatives of p-tert-butylcalix[4]arene for oxyanion recognition: synthesis and complexation studies(TAYLOR & FRANCIS LTD, 2009) Yilmaz, Aydan; Tabakci, Begum; Tabakci, MustafaWe have prepared new diamino derivatives of p-tert-butylcalix[4]arene from the reduction of corresponding amide derivatives. The examination of their recognition abilities towards some selected oxyanions shows that the new calix[4]arene amines are mostly more effective receptors than their amide derivatives for dichromate anions and nitrite, and capable of extracting these anions in yields as high as 95%. However, neither the calix[4]arene amines nor their corresponding amides were capable of extracting phosphate or nitrate at pH 1.5.Öğe Preparation, characterization of cellulose-grafted with calix[4]arene polymers for the adsorption of heavy metals and dichromate anions(ELSEVIER SCIENCE BV, 2007) Tabakci, Mustafa; Erdemir, Serkan; Yimaz, MustafaIn this paper, the adsorbents were prepared from cellulose-grafted with calix[4]arene polymers (CGC[4]P-1 and CGC[4]P-2) and their sorption properties studied. The polymers were characterized by Fourier transform infrared spectroscopy, elemental analysis, thermal gravimetric analysis and scanning electron microscopy. They were then used to evaluate the sorption properties of some heavy metal cations (CO2+, Ni2+, cu(2+), Cd2+, Hg2+ and Pb2+) and dichromate anions (Cr-2,O-7(2-)/HCr,O-7(-)). Results showed that CGC[4]P-2 was a good sorbent for heavy metal cations while CGC[4]P-1 was ineffective. In the studies of dichromate anion sorption, it was observed that CGC[4]P-2 was a more highly effective sorbent at pH 1.5 than was CGC[4]P-1. (c) 2007 Elsevier B.V. All rights reserved.Öğe Rapid and real-time detection of arginine enantiomers by QCM sensor having a Calix[4]arene receptor bearing asymmetric centers(ELSEVIER, 2019) Temel, Farabi; Erdemir, Serkan; Ozcelik, Egemen; Tabakci, Begum; Tabakci, MustafaThis paper describes the sensing studies of a chiral calix[4]arene receptor (5) having (R)-2-phenylglycinol moiety for arginine enantiomers (D-/L-arginine) by using Quartz Crystal Microbalance (QCM) technique. The initial experiments have revealed that the chiral calix[4]arene 5 coated QCM (CCC-QCM) sensor showed good sensing for arginine enantiomers, such that it has exhibited higher sensing towards D-arginine than that of L-arginine. It has been determined that the sensitivity, limit of detection values of CCC-QCM sensor for the D-/L-arginine solutions as 0.024/0.023 Hz/mu M and 0.38/1.29 mu M, respectively. On the other hand, the racemic mixture studies were optimized using the response surface methodology with central composite design. Consequently, it has been demonstrated that the QCM sensor modification with a calix[4]arene receptor bearing asymmetric centers provided rapid, real-time, sensitive and effective sensing of arginine enantiomers.Öğe Removal of lindane from an aqueous solution by using aminopropyl silica gel-immobilized calix[6]arene(ELSEVIER SCIENCE BV, 2013) Tor, Ali; Aydin, Mehmet Emin; Aydin, Senar; Tabakci, Mustafa; Beduk, FatmaAn aminopropyl silica gel-immobilized calix[6]arene (C[6]APS) has been used for the removal of lindane from an aqueous solution in batch sorption technique. The C[6]APS was synthesized with p-tert-butylcalix[6]arene hexacarboxylate derivative and aminopropyl silica gel in the presence of N,N'-diisopropyl carbodiimide coupling reagent. The sorption study was carried out as functions of solution pH, contact time, initial lindane concentration, C[6]APS dosage and ionic strength of solution. The matrix effect of natural water samples on the sorption efficiency of C[6]APS was also investigated. Maximum lindane removal was obtained at a wide pH range of 2-8 and sorption equilibrium was achieved in 2 h. The isotherm analysis indicated that the sorption data can be represented by both Langmuir and Freundlich isotherm models. Increasing ionic strength of the solutions increased the sorption efficiency and matrix of natural water samples had no effect on the sorption of lindane. By using multilinear regression model, regression equation was also developed to explain the effects of the experimental variables. (C) 2013 Elsevier B.V. All rights reserved.Öğe Sensing abilities of functionalized calix[4]arene coated QCM sensors towards volatile organic compounds in aqueous media(ELSEVIER SCIENCE BV, 2017) Temel, Farabi; Ozcelik, Egemen; Ture, Ayse Gul; Tabakci, MustafaThis study presents the sensing studies of QCM sensors which coated with calix[4]arene derivatives bearing different functional groups towards some selected Volatile Organic Compounds (VOCs). Initial experiments revealed that QCM sensor coated with calix-3 bearing bromopropyl functionalities was relatively more effective sensor for methylene chloride (MC) emissions than the other calix[4]arene coated QCM sensors, in aqueous media. In further experiments, this effective calix-3 coated QCM sensor were used in detailed sensing studies of selected VOCs. However, the results demonstrated that calix-3 coated QCM sensor was most useful sensor for toluene (TOL) emissions among all. Moreover, the sensing of TOLs with calix-3 coated QCM sensor was also evaluated in terms of sorption phenomena. Consequently, calix-3 coated QCM sensor was good sensor for TOL emissions, and thus it demonstrated that the coating of QCM sensor surface with calixarenes was good approach for sensing of the VOCs. (C) 2017 Elsevier B.V. All rights reserved.Öğe Synthesis and application of an efficient calix[4]arene-based anion receptor bearing imidazole groups for Cr(VI) anionic species(PERGAMON-ELSEVIER SCIENCE LTD, 2012) Tabakci, Mustafa; Tabakci, Begum; Beduk, A. DincerWe synthesized the new calix[4]arene amines bearing two and four imidazole or tert-butylamine moieties (9a,b/10a,b) by the reaction of di-or tetra-tosylated calix[4]arene derivatives (7 and 8, respectively) with 1-(3-aminopropyl)imidazole and/or tert-butylamine, respectively. After the characterization of 9a,b/10a,b their extraction abilities toward Cr(VI) anionic species (CAS) was evaluated and compared by the liquid liquid extraction method. The extraction results revealed that calix[4]arene amine having four imidazole groups (10a) was an efficient anion receptor for CAS. Moreover, the extraction of CAS by 10a in the presence of other anions such as Cl-, NO3-, and PO43- showed that 10a could be a selective anion receptor for CAS in the presence of those anions. (C) 2012 Elsevier Ltd. All rights reserved.Öğe Synthesis and Characterization of PVA/Calix[4]arene Fibers(TAYLOR & FRANCIS INC, 2013) Kocyigit, Serhat; Tabakci, Mustafa; Ozaytekin, IlkayIn this study, both boron-doped and -undoped poly(vinyl alcohol)/Calix[4]arene fibers were prepared by using an electrospinning technique. Obtained fibers were characterized by FT-IR, DSC, and SEM techniques. The DSC results show that the degradation of the boron-doped fibers started at much higher temperatures. This result indicates the addition of boron increased the thermal stability of the fibers. SEM pictures show that both of the fiber samples are nonbeaded with diameters ranging from 0.5 to 1 mu m. The fiber diameters are not homogeneous and uniformly distributed for boron-undoped samples.Öğe Synthesis and evaluation of the Cr(VI) extraction ability of amino/nitrile calix[4]arenes immobilized onto a polymeric backbone(ELSEVIER SCIENCE BV, 2006) Memon, Shahabuddin; Tabakci, Mustafa; Roundhill, D. Max; Yimaz, MustafaThree new calix[4]arene based polymeric resins (6, 7 and 8) have been synthesized via nucleophilic substitution reactions involving 5,11,17,23-tetrakis-[(N,N-dimethylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene 3, and 5,11,17,23-tetracyanomethyl-25,26,27,28-tetrahydroxycalix[4]arene 4 as precursors with a Merrifield resin. The extraction studies were made by using liquid-liquid extraction, solid-liquid batchwise and packed-column sorption procedures, and effect of different anion to extraction of dichromate anion was examined by using NO3-, Cl-, SO42- and their mixtures. The experimental tal results showed that these calix[4]arene based polymeric resins have high extraction abilities towards Na2Cr2O7 as compared to their monomeric precursors, and also dichromate anion was extracted in high ratios even in presence of different anions. (c) 2006 Elsevier B.V. All rights reserved.
