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Öğe Adsorption of acid dyes in aqueous solutions by shells of bittim (Pistacia khinjuk Stocks)(Elsevier, 2006) Aydin, Haluk; Baysal, GulayThe effectiveness of adsorption for dye removal from wastewaters has made it an ideal alternative to other expensive treatment options. The removal of acid red 183 (AR) and acid green 25 (AG) onto shells of bittim (Pistacia khinjuk Stocks) (BTS) from aqueous solutions was investigated using parameters such as contact time, pH, temperature, adsorbent doses, and initial dye concentration. Adsorption isotherms of dyes onto BTS were determined and correlated with common isotherm equations such as the Langmuir and Freundlich models. Adsorption equilibrium was reached within 30 min. It was found that the Langmuir isotherm appears to fit the isotherm data better than the Freundlich isotherm. Parameters of the Langmuir and Freundlich isotherms were determined using adsorption data. The maximum adsorption capacities for AR and AG onto BTS at 308, 313, and 318 K were found to be 33, 28, and 20; 16, 18, and 7 mg/g, respectively. The adsorption kinetics of AR and AG could be described by the pseudo-second-order reaction model. The data obtained from adsorption isotherms at different temperatures were used to calculate several thermo-dynamic quantities such as the Gibbs energy (Delta G(0)), enthalpy (Delta H-0), and entropy (Delta S-0) of adsorption. The adsorption process was found to be spontaneous, endothermic and physical in nature. Locally available adsorbent BTS was found to have a low cost and was promising for the removal of AR and AG from aqueous solutions.Öğe Comparison dielectric and thermal properties of polyurethane/organoclay nanocomposites(Elsevier, 2013) Baysal, Gulay; Aydin, Haluk; Koytepe, Suleyman; Seckin, TurgayPolyurethane composites were obtained with different organoclay contents. The organoclay Na+-montmorillonite was dispersed in the PU matrix by mixing method from solution. Na+-montmorillonite was modified with dodecyl ammonium sulphate and 1-methyl-3-octyl imidazolium tetrafluoroborate. The nanocomposites obtained by using different modifier were compared in terms of dielectric and thermal properties. The dispersion state of the organoclay particles and its effect on the thermogravimetric and dielectric properties of the composites was investigated. The characterization of PU/organoocl ay composites was carried out by means of scanning electron microscopy, Fourier transform infrared, thermogravimetric analysis and X-ray diffraction. The dielectric properties of the PU/organoclay nanocomposites were studied in detail. The obtained PU/organoclay intercalated nanocomposites exhibited better thermal stability and improved lower dielectric constants than the pure PU. (C) 2013 Elsevier B.V. All rights reserved.Öğe Comparison of Analysis Results and Modification of Na+-Montmorillonite with Ionic Liquids(Asian Journal Of Chemistry, 2014) Baysal, Gulay; Aydin, HalukIn this study, preliminary data are reported on the modification of sodium montmorillonite modified with imidazolium and pyridinium-based ionic liquids. Commercially available unmodified clay was treated under different conditions with aqueous solutions of three ionic liquids such as 1-butyl 3-methyl imidazolium tetrafluoroborate, 1-butyl 4-methyl pyridinium tetrafluoroborate and 1-methyl 3-octyl imidazolium tetrafluoroborate and the results were compared with ammonium dodecyl sulphate. The modified materials were characterized by FTIR, TGA, SEM and WXRD analysis. The analysis results show an overall increase in interlamellar spacing as a result of sodium cation exchange with the cations of the ionic liquids and long chain quaternary ammonium salt. The thermal stabilities of the organoclays is higher than unmodified clay.Öğe Equilibrium and kinetic studies of copper (II) ion uptake by modified wheat shells(Desalination Publ, 2012) Aydin, Haluk; Yerlikaya, Cigdem; Uzan, SerhatNatural adsorbents such as shells of unmodified wheat (RW), and modified wheat (MW) were assessed for Cu(II) adsorption from aqueous solutions. The removal of Cu(II) by these adsorbents from aqueous solution was investigated by using several parameters such as modificiation, contact time, temperature and pH. The extent of Cu(II) removal increased with increasing contact time, temperature and pH and also with modification by Reactive Orange 122 of adsorbent. The experimental data were analysed by the Langmuir and Freundlich models of adsorption. It was found that the Freundlich equation fits better than the Langmuir equation. In addition, the adsorption data obtained at different temperatures of Cu(II) by adsorbents were applied to pseudo first-order, pseudo second-order and Weber-Morris equations, and the rate constants of first-order adsorption (k(1)), the rate constants of second-order adsorption (k(2)) and diffusion rate constants (k(3)) at these temperatures were calculated, respectively. The rates of adsorption were found to conform to pseudo second-order kinetics with good correlation (R-2 >= 0.989). The data obtained from adsorption isotherms at different temperatures were used to calculate some thermodynamic quantities such as free energy of adsorption (Delta G degrees), enthalpy (Delta H degrees), and entropy (Delta S degrees). It is found that Delta G degrees is negative, indicating that the nature of adsorption process for Cu(II) is spontaneous. The positive value of Delta H degrees indicates that the adsorption of Cu(II) onto adsorbents is an endothermic process. The positive value of Delta S degrees reflects the affinity of the adsorbent for Cu(II). As a result, the present work indicates that the wheat shells MW chemically by Reactive Orange 122, possess more efficiency in adsorbing Cu(II) ions than the unmodified one (RW).Öğe Equilibrium and kinetics studies for adsorption of direct blue 71 from aqueous solution by wheat shells(Elsevier Science Bv, 2007) Bulut, Yasemin; Gozubenli, Numan; Aydin, HalukThis paper deals with the application of wheat shells (WS), an agricultural by-product, for the removal of direct blue 71 (DR) from aqueous solution. The characteristics of WS surface, such as surface area, Bohem titration and scanning electron microscopy (SEM) were obtained. The removal of direct blue 71 onto WS from aqueous solution was investigated by using parameters, such as pH, temperature, adsorbent dose, contact time and initial concentration. The adsorption process attains equilibrium within 36h. The extent of dye removal decreased with increasing adsorbent dosage and also increased with increasing contact time, temperature, in solution concentration. Optimum pH value for dye adsorption was determined between 6 and 8. The experimental data were analysed by the Langmuir and Freundlich models of adsorption. It was found that the Langmuir equation fit better than the Freundlich equation. Maximum adsorption capacity (Qm) was calculated as at different temperatures (293, 303 and 313 K) 40.82, 45.66 and 46.30 mg g(-1), respectively. In addition, the adsorption data obtained at different temperatures of DR by WS were applied to pseudo first-order, pseudo second-order and Weber-Morris equations, and the rate constants of first-order adsorption (kj), the rate constants of second-order adsorption (k(2)) and intraparticle diffusion rate constants (k(3)) at these temperatures were calculated, respectively. The rates of adsorption were found to conform to pseudo second-order kinetics with good correlation (R-2 > 0.9904). Also, free energy of adsorption (Delta G degrees), enthalpy (Delta H degrees), and entropy (Delta S degrees) changes were determined to predict the nature of adsorption. Furthermore, the results indicate that WS could be employed as a low-cost alternative to other adsorbents in the removal of direct blue 71 from aqueous solution. (C) 2006 Elsevier B.V. All rights reserved.Öğe Improvement of Synthesis and Dielectric Properties of Polyurethane/Mt-QASs+ (Novel Synthesis)(Springer, 2016) Baysal, Gulay; Aydin, Haluk; Hosgoren, Halil; Uzan, Serhat; Karaer, HaticePolyurethane-based nanocomposites were prepared and their dielectric properties were characterized. Polyurethane (PU) composites were prepared with different organoclay content (1, 3, 5, and 10 wt% for all cases). The composites included quaternary ammonium salts such as 1-methyl-di-octyl-1 phenyl ammonium iodide (QAS-1), 1-methyl-di-nonyl-1 phenyl ammonium iodide (QAS-2), and 1-methyl-di-dodecyl-1 phenyl ammonium iodide (QAS-3) which were newly synthesized for modification of Na+-montmorillonite. Addition of aluminum silicate enhanced the dielectric properties at a constant concentration. Dielectric constants of nanocomposites compounded with 3 %- and 5 %-organoclay were close in value. The characterization of PU/organoclay composites was carried out using Fourier transform infrared and X-ray diffraction.Öğe Investigation of Antimicrobial Properties of QASs+ (Novel Synthesis)(Maik Nauka/Interperiodica/Springer, 2018) Baysal, Gulay; Aydin, Haluk; Uzan, Serhat; Hosgoren, HalilQuaternary ammonium salts (QASs) are bioactive materials known for their antimicrobial effects. However, it is difficult to provide desirable quaternary ammonium salts. Thus, firstly new quarternary ammonium salts which are not in the literature were synthesized and organoclays were prepared with different quarternary ammonium salts content. The organoclays included quaternary ammonium salts such as N,N-di (3-methyl butyl)-N-(1-phenylethyl)-N-methyl ammonium Iodide (QAS-1), N,N-dipentil-N-(1-phenylethyl)-N-methyl ammonium Iodide (QAS-2), and N,N-dihexcyl-N-(1-phenylethyl)-N-methyl ammonium Iodide (QAS-3) which were newly synthesized for modification of Na+-montmorillonite (Na+-Mt) and were characterized by nuclear magnetic resonance spectroscopy (NMR). Synthesized organoclays were characterized by using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Characterization results proved that the modification is performed with high performance and as seen in the XRD results, the interstratum distances increased considerably and the diffraction angles decreased. The antimicrobial activity of the organoclays against Staphylococcus aureus and Escherichia coli were studied in detail and were obtained much larger inhibition zones than similar studies. QAS-3-Mt organoclay showed the maximum of antimicrobial activity against S. aureus and E. coli. As is known, organoclay comes among the fillers that play the most effective role in the synthesis of composite materials. In this context, the product we have synthesized is unique and can be used for many purposes.Öğe A kinetics and thermodynamics study of methylene blue adsorption on wheat shells(Elsevier, 2006) Bulut, Yasemin; Aydin, HalukThe use of wheat shells (WMS) for the removal of methylene blue from aqueous solutions at different contact times, temperatures, pH, adsorbent doses and initial dye concentration was investigated. The adsorption process attains equilibrium within 60 min. The extent of dye removal decreased with increasing adsorbent dosage and also increased with increasing contact time, temperature, and in solution concentration. The adsorption isotherms are described by means of the Langmuir and Freundlich isotherms. It was found that the Langmuir equation fit better than the Freundlich equation. Maximum adsorption capacity (Q(m)) was calculated at different temperatures (303, 313, and 323 K) 16.56, 20.83, and 21.50 mg/g, respectively. The adsorption kinetics of methylene blue could be described by the pseudo-second-order reaction model. The activation energy of system (E-a) was calculated as 16.62 kJ/mol. Free energy of adsorption (Delta G(0)), enthalpy (Delta H-0), and entropy (Delta S-0) changes were calculated to predict the nature of adsorption. The estimated values for Delta G(0) were -22.64, -24.11, and -26.35 kJ/mol at 303, 313, and 323 K, respectively, which are rather low, indicating that a spontaneous process occurred. The enthalpy changes and entropy of adsorption were 33.41 kJ/mol and 185 J/mol K, respectively. The obtained results are: (1) high levels of color removal (> 95%) were achieved with low contact times adsorbent/dye (less than 90-min contact); and (2) the whole WHS can be successfully used as adsorbent of methylene blue in aqueous solutions. WHS, an inexpensive and easily available material, can be an alternative for more costly adsorbents used for dye removal in wastewater treatment processes.Öğe A new method: measurement of microleakage volume using human, dog and bovine permanent teeth(Univ Catolica De Valparaiso, 2006) Yavuz, Izzet; Aydin, Haluk; Ulku, Refik; Kaya, Sadullah; Tumen, CanerThis study investigates the feasibility of a different new approach to determining the microleakage volume associated with dental restorations (Class V cavity restorated with glass ionomer cement + high copper amalgam) and the relative marginal adaptation deficiency of dog, bovine and human permanent teeth in in vitro conditions. Also researched is the appropriateness of using dog and bovine teeth in in vitro studies rather than human teeth. Our method utilizes the molecular adsorption characteristics of methylene blue. Within the framework of this study, 60 permanent teeth (20 human, 20 dogs and 20 bovine) were used. These groups were evaluated statistically, of which indicated no statistically significant differences (p > 0.05). It was also concluded that this preliminary investigation showed that the new microleakage volume measurement method may be a valuable new technique for the in vitro study of microleakage dynamics around dental restorations.Öğe Organogels as novel carriers for dermal and topical drug delivery vehicles(Pergamon-Elsevier Science Ltd, 2016) Uzan, Serhat; Baris, Deniz; Colak, Mehrnet; Aydin, Haluk; Hosgoren, HalilAminoalcohol based bis-(aminoalcohol)oxalamides (BAOAs) (1,6-amino alcohol=leucinol, isoleucinol, valinol, phenyiglycinol, phenylalaninol and 2-amino-1-butanol) have been explored to develop drug depot systems and illustrated as a novel dermal and topical drug delivery vehicle for non-steroidal anti-inflammatory drug molecules. FAE's (Fatty acid ethyl and isopropyl esters) with different chain lengths, ethyl laurate, ethyl myristate, ethyl palmitate, isopropyl laurate, isopropyl myristate, isopropyl palmitate, have been chosen as they are biocompatible organic fluids used typically in cosmetic industry. Ibuprofen (Ib), acting as a model drug, was entrapped in the supramolecular organogels. The release behavior of Ib molecules in the supramolecular organogels was investigated by using UV-vis spectroscopy. The influence of the organogelator and drug concentration, pH values of the accepting media, and nature of solvent (different FAE's) on the release behavior of Ib was investigated under static conditions. The results indicated that the release rate of Ib from the supramolecular organogels was effectively retarded with an increase of the organogelator concentration. Also, the release rates of Ib increased on increasing the Ib content. Furthermore, the release behavior of Ib was found to be different at various pH values in buffers as accepting media. The study of the release kinetics indicated that the release behavior of Ib was in accord with the Higuchi equation and the diffusion-controlled mechanism involved in the Fickian model. These observations indicate that bis-(aminoalcohol)oxalamides gels may act as delivery vehicles for non-steroidal anti-inflammatory drug molecules and also show that the release profiles for such systems can be fine-tuned by the correct choice of gelator-FAE combination. (C) 2016 Elsevier Ltd. All rights reserved.Öğe Removal of copper (II) from aqueous solution by adsorption onto low-cost adsorbents(Academic Press Ltd- Elsevier Science Ltd, 2008) Aydin, Haluk; Buluta, Yasemin; Yerlikaya, CigdemThe use of low-cost adsorbents was investigated as a replacement for current costly methods of removing metals from aqueous solution. Removal of copper (11) from aqueous solution by different adsorbents such as shells of lentil (LS), wheat (WS), and rice (RS) was investigated. The equilibrium adsorption level was determined as a function of the solution pH, temperature, contact time, initial adsorbate concentration and adsorbent doses. Adsorption isotherms of Cu (II) on adsorbents were determined and correlated with common isotherm equations such as Langmuir and Freundlich models. The maximum adsorption capacities for Cu (11) on LS, WS and RS adsorbents at 293, 313 and 333 K temperature were found to be 8.977, 9.510, and 9.588; 7.391, 16.077, and 17.422; 1.854, 2.314, and 2.954 mg g(-1), respectively. The thermodynamic parameters such as free energy (Delta G(0)), enthalpy (Delta H-0) and entropy changes (Delta S-0) for the adsorption of Cu (II) were computed to predict the nature of adsorption process. The kinetics and the factors controlling the adsorption process were also studied. Locally available adsorbents were found to be low-cost and promising for the removal of Cu (II) from aqueous solution. (C) 2007 Elsevier Ltd. All rights reserved.Öğe Synthesis, characterization, thermal and electrochemical features of poly (phenoxy-imine)s containing pyridine and pyrimidine units(Springer, 2020) Yagmur, Hatice Karaer; Kaya, Ismet; Aydin, HalukPoly (4-hydroxybenzaldehyde) was prepared by via the oxidative polymerization process in an aqueous alkaline medium by H2O2 as an oxidant. Then, poly(phenoxy-imine)s were synthesized from the condensation reactions of poly(4-hydroxybenzaldehyde) (P-4HBA) with several amines including pyridine and pyrimidine groups. The structures and characterizations of compounds were made by virtue of FT-IR, NMR, UV-Vis spectroscopy, GPC, TG, DSC, CV, SEM and fluorescence (FL) analyses. The conductivities of poly (phenoxy-imine)s were determined with electrometer by four-point probe technique. The conductivity values of poly (phenoxy-imine)s were increased to be connect with doped factor of iodine. Moreover, the electrical conductivity of the poly (phenoxy-imine)s was also measured and defined which they had semi-conductive features. Fluorescence properties of poly (phenoxy-imine)s and P-4HBA were measured out in DMF solutions to define the optimum concentrations in order to acquire the maximal FL intensities. Average molecular weight of the polymers in number (M-n), and in weight (M-w), and polydispersity index (PDI) values of poly (phenoxy-imine)s and P-4HBA were found from GPC analysis. The M-n, M-w and PDI values of P-4HBA were found to be 9900 Da (M-n), 11,300 Da (M-w) and 1.14, respectively. The electrochemical energy gap (E'(g)) and optical band gap (E-g) values of poly (phenoxy-imine)s were determined from cyclic voltammetry (CV) and UV-Vis measurements, respectively.Öğe Synthesis, characterization, thermal and electrochemical properties of imine polymers containing pyridine and pyrimidine units(Industrial Chemistry Research Inst, 2017) Karaer, Hatice; Kaya, Ismet; Aydin, HalukSchiff bases polymers were synthesized from 2-hydroxybenzaldehyde (2-HBA) vin oxidative polymerization method in an aqueous alkaline medium in the presence of NaOCI as an oxidant. Then, these polymeric Schiff bases were prepared from the polyaldehyde by grafting each of them with different amines containing pyridine and pyrimidine groups. The structures of polymers were confirmed by FT-IR, H-1 NMR, C-13 NMR, and UV-Vis measurements. The polymers were characterized by GPC and SEM analyses. Furthermore, their optical properties were determined by UV-Vis and fluorescence spectroscopy, their electrochemical properties by cyclic voltammetry (CV) analysis and solid state conductivity measurements by the four-point probe technique, their thermal behavior by TG, DTA, and DSC measurements. The electrical conductivity of the polymers was also measured and found that they are semiconductive. The number average molecular weight ((M) over bar (u)), the weight average molecular weight ((M) over bar (w)), and dispersity (D) values of the polymers were found from GPC analysis and were equal 5900, 5450 and 1.08, respectively, for poly(2-hydroxybenzaldehyde) (P-2HBA) polymer. Electrochemical energy gap (E-s) was found by CV, whereas optical band gap (E-s,) was determined by UV-Vis measurements.Öğe Utilization of shells of hazelnut modified with Reactive Orange 122 as adsorbent for the removal of Cu(II)(Desalination Publ, 2010) Aydin, Haluk; Yerlikaya, CigdemThe influence of reactive dye modification on the efficiency of adsorption capacities of hazelnut shells was investigated. To that end, natural adsorbents such as shells of unmodified hazelnut (RH), and modified hazelnut (MH) were used. The removal of Cu(II) by these adsorbents from aqueous solution was investigated by using several parameters such as modification, contact time, temperature and pH. The adsorption process attained equilibrium within 60 min. The extent of Cu(II) removal increased with increasing the contact time, temperature and pH and also with modification by Reactive Orange 122 as the adsorbent. Optimum pH value for Cu(II) adsorption was determined between 4-5. The experimental data were analysed by the Langmuir and Freundlich models of adsorption. It was found that the Langmuir equation fited better than the Freundlich equation. The maximum adsorption capacities for Cu(II) onto RH and MH at 298, 308 and 318 K were found to be 3.95, 4.65, and 4.74, 7.00, 8.12 and 8.61 mg/g, respectively. In addition, the adsorption data obtained at different temperatures of Cu(II) by adsorbents were applied to the pseudo first-order, pseudo second-order and Weber-Morris equations, and the rate constants of the first-order adsorption (k(1)), the rate constants of the second-order adsorption (k(2)) and intraparticle diffusion rate constants (k(3)) at these temperatures were calculated, respectively. The rates of adsorption were found to conform the pseudo second-order kinetics with good correlation (R-2 >= 0.991). The data obtained from the adsorption isotherms at different temperatures were used to calculate some thermodynamic quantities such as free energy of adsorption (Delta G degrees), enthalpy (Delta H degrees) and entropy (Delta S degrees). It is expected that Delta G degrees is negative, indicating that the nature of the adsorption process for Cu(II) is spontaneous. The positive value of Delta H degrees indicates that the adsorption of Cu(II) onto adsorbents is an endothermic process. The positive value of Delta So reflects the affinity of the adsorbent for Cu(II). As a result, the hazelnut shells (both modified and unmodified), inexpensive and easily available material, can be an alternative for more costly adsorbents used for Cu((II) removal from wastewater.Öğe Utilization of walnut shells (Juglans regia) as an adsorbent for the removal of acid dyes(Desalination Publ, 2009) Aydin, Haluk; Baysal, Guelay; Bulut, YaseminThe removal of acid red 183 and acid green 25 onto walnut shells (Juglans regia) (WS) from aqueous solutions was investigated by using parameters such as contact time, temperature, pH, adsorbent doses and initial dye concentration. Adsorption equilibrium was reached within 30 min. The adsorption isotherms were described by means of the Langmuir and Freundlich isotherms. It was found that the Langmuir isotherm appears to fit the isotherm data better than the Freundlich isotherm. The maximum adsorption capacities for acid red 183 and acid green 25 on WS at 308,313, and 318 K were found to be 45,37, and 37; 21,14, and 7 mg g(-1), respectively. The data obtained from adsorption isotherms at different temperatures were used to calculate some thermodynamic quantities Such as free energy of adsorption (Delta G(0)), enthalpy (Delta H(0)), and entropy (Delta S(0)). That G(0) is negative, indicating that the nature of adsorption process for dyes is spontaneous. The positive value of H(0) indicates that the adsorption of dyes onto WS is an endothermic process. The positive value of S(0) reflects the affinity of the adsorbent for dyes. The kinetics and the factors controlling the adsorption process were also studied. The adsorption process followed a second-order model. WS, being a cheap, and easily available material, can be an alternative for more costly adsorbents used for dye removal in wastewater treatment processes.
