Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
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Article Citation - WoS: 56Citation - Scopus: 58Clinoptilolite Supported Rutile Tio2 Composites: Synthesis, Characterization, and Photocatalytic Activity on the Degradation of Terephthalic Acid(Elsevier Ltd., 2017) Yener, H. B.; Yılmaz, M.; Deliismail, Özgün; Özkan, Seher Fehime; Helvacı, Şerife ŞerefClinoptilolite supported rutile TiO2 composites were synthesized for the enhancement of its photocatalytic performance in the degradation of the aqueous terephthalic acid solution under UVC illumination by the increase in its surface area and to simplify its recovery from the treated solution after use. The XRD spectra of the composites revealed the formation of pure rutile TiO2 on the surface of the clinoptilolite. The SEM images showed the formation of the spherical TiO2 clusters were composed of nano fibers on the surface of the clinoptilolite. For all composites synthesized, the dispersion of the TiO2 particles on the clinoptilolite led to a surface area larger than that of the bare TiO2 and clinoptilolite. The materials synthesized in the present study exhibited higher catalytic activity compared with the commercial Degussa P25 and anatase. Among the catalysts synthesized the TiO2/clinoptilolite with a weight ratio of 0.5 was found to be the most photoactive catalyst even though it contains a lesser amount of active TiO2. The kinetic of the reactions for different catalyst was found to be consistent with the pseudo-first order kinetic model. The results of the Langmuir-Hinshelwood model showed the slight contribution of the adsorption on the degradation. The activity of the TiO2/clinoptilolite with a weight ratio of 0.5 decreased after repetitive use due to the accumulation of the TPA molecules on the surface of the catalyst.Article Citation - WoS: 35Citation - Scopus: 41Batch and Column Studies on Heavy Metal Removal Using a Local Zeolitic Tuff(Elsevier Ltd., 2010) Balköse, Devrim; Ülkü, Semra; Can, ÖzgeIon exchange is considered to be one of the most cost effective methods if low cost ion exchangers such as natural zeolites are used in waste water treatment. In this study, a zeolitic tuff rich in clinoptilolite from Gördes Manisa Turkey was examined to evaluate its ion exchange performance for the removal of copper, nickel and cobalt ions from metal (II) nitrate solutions at various concentrations by performing both batch and packed column experiments. A clinoptilolite tuff with purity around 60% was used in ion exchange experiments. Copper, nickel and cobalt exchange capacities of the tuff were determined as 8.3mg (0.26meq) Cu2+/g, 6.6mg (0.23meq) Ni2+/g and 4.5mg (0.15meq) Co2+/g, respectively. The equilibrium behavior of the system was best described by classical Langmuir model. The experimental breakthrough curves from the column experiments were fitted to solid diffusion control model. The study showed that efficient metal ion removal can be done by using the local clinoptilolite rich tuff. © 2010 Elsevier B.V.Article Citation - WoS: 45Citation - Scopus: 55Incorporation of Iron Nanoparticles Into Clinoptilolite and Its Application for the Removal of Cationic and Anionic Dyes(Korean Society of Industrial Engineering Chemistry, 2015) Nairat, Muath; Shahwan, Talal; Eroğlu, Ahmet Emin; Fuchs, HaraldThis study reports the preparation of composite sorbents of iron nanoparticles (nZVI) and clinoptilolite at various iron/clinoptilolite ratios. The composites were characterized using various characterization techniques. The material was used for the removal of methylene blue (MB) and methyl orange (MO) as model cationic and anionic dyes. The experiments investigated the effects of time, loading, initial pH, reusability, and temperature on the removal process. According to the results, Cl-nZVI showed fast and quantitative removal over a wide range of concentrations. The removal process was endothermic in nature, and the composite demonstrated reusability for several trials.Article Citation - WoS: 10Citation - Scopus: 10Clinoptilolite-Rich Mineral as a Novel Carrier for the Active Constituents Present in Ginkgo Biloba Leaf Extract(Elsevier Ltd., 2008) Göktaş, Selda; Ülkü, Semra; Bayraktar, OğuzThe possible use of clinoptilolite-rich mineral as a novel carrier for the active constituents present in Ginkgo biloba leaf extract solutions was investigated. The flavonoid aglycone constituents were found to be selectively adsorbed on the clinoptilolite surface. The antioxidant activity determinations of the extract solutions were performed by the Trolox Equivalent Antioxidant Capacity (TEAC) assay. The antioxidant activity measurements performed for the Ginkgo leaf extract solutions showed decreasing antioxidant activities due to adsorption. The decrease in antioxidant activity was attributed to the adsorption of phenolic constituents on the clinoptilolite surface.Article Citation - WoS: 112Citation - Scopus: 130The Effect of Hcl Treatment on Water Vapor Adsorption Characteristics of Clinoptilolite Rich Natural Zeolite(Elsevier Ltd., 2005) Çakıcıoğlu Özkan, Fehime; Ülkü, SemraIn this study, water vapor adsorption properties of the clinoptilolite rich zeolite tuff, from Bigadic (Turkey), and its modified forms were examined. The modified forms were obtained by treating the tuff with HCl solutions (0.032, 0.16, 0.32, 1.6 or 5 M) at 25,40,75 and 100°C for 3 h. Infrared spectroscppy and water vapor adsorption were used for the characterization of the zeolites. Langmuir, BET and Dubinin-Raduschevich methods were applied in the analysis of water vapor adsorption data. Applications of Dubinin Raduschevich equation to the water adsorption data displayed that the super-micropore volume was not very sensitive to acid treatment. It was found out that the Langmuir surface area and ultra-micropore volume depend on the degree of the removal of aluminum from the structure.Article Citation - WoS: 249Citation - Scopus: 268Silver, Zinc, and Copper Exchange in a Na-Clinoptilolite and Resulting Effect on Antibacterial Activity(Elsevier Ltd., 2004) Top, Ayben; Ülkü, SemraAg+-Na+, Zn2+-Na+, and Cu2+-Na+ equilibria for clinoptilolite-rich mineral from Gördes (Western Anatolia) were investigated at 25 °C and 0.1 N total solution normality. While silver exchange was favorable over the whole concentration range, zinc and copper were partially exchanged and preferred only at low concentrations. The standard free energies of exchanges for Ag+-Na+, Zn2+-Na+, and Cu2+-Na+ pairs were found as -6.0, 2.03, and 3.09 kJ/equiv., respectively. From these values, selectivity sequence was determined as Ag+>Na+ >Zn2+>Cu2+. Antibacterial activities of the exchanged samples were measured as a function of exchange level against Pseudomonas aeruginosa and Escherichia coli. Considering the selectivity sequence of the clinoptilolite and antibacterial activity results, Ag-clinoptilolite seemed to be promising antibacterial material.Article Citation - WoS: 47Citation - Scopus: 52Isomerization of ?-Pinene Over Ion-Exchanged Natural Zeolites(Elsevier Ltd., 2003) Özkan, Fehime; Gündüz, Gönül; Akpolat, Oğuz; Beşün, Nurgün; Murzin, Dmitry Yu.Catalysts prepared by ion exchange of clinoptilolite-based natural zeolite tuffs with NH4 +, Ba2+ and Pb2+ were investigated in the isomerization reaction of α-pinene at atmospheric pressure under nitrogen flow. Activity and selectivity to mono-, bi- and tricyclic products were correlated with acidity strength.Article Citation - WoS: 50Citation - Scopus: 53Physicochemical Characterization of the Retardation of Aqueous Cs+ Ions by Natural Kaolinite and Clinoptilolite Minerals(Elsevier Ltd., 2005) Shahwan, Talal; Akar, Dilek; Eroğlu, Ahmet EminThe aim of this study was to carry out kinetic, thermodynamic, and surface characterization of the sorption of Cs+ ions on natural minerals of kaolinite and clinoptilolite. The results showed that sorption followed pseudo-second-order kinetics. The activation energies were 9.5 and 13.9 kJ/mol for Cs+ sorption on kaolinite and clinoptilolite, respectively. Experiments performed at four different initial concentrations of the ion revealed that the percentage sorption of Cs+ on clinoptilolite ranged from 90 to 95, compared to 28 to 40 for the kaolinite case. At the end of a 1 week period, the percentage of Cs+ desorption from clinoptilolite did not exceed 7%, while it amounted to more than 30% in kaolinite, indicating more stable fixation by clinoptilolite. The sorption data were best described using Freundlich and D–R isotherm models. Sorption showed spontaneous and exothermic behavior on both minerals, with ΔH0 being −6.3 and −11.4 kJ/mol for Cs+ uptake by kaolinite and clinoptilolite, respectively. Expanding the kaolinite interlayer space from 0.71 to 1.12 nm using DMSO intercalation, did not yield a significant enhancement in the sorption capacity of kaolinite, indicating that the surface and edge sites of the clay are more energetically favored. EDS mapping and elemental analysis of the surface of kaolinite and clinoptilolite revealed more intense signals on the surface of the latter with an even distribution of sorbed Cs+ onto the surfaces of both minerals.Article Citation - WoS: 62Citation - Scopus: 60Preconcentration and Atomic Spectrometric Determination of Rare Earth Elements (rees) in Natural Water Samples by Inductively Coupled Plasma Atomic Emission Spectrometry(Elsevier Ltd., 2005) Pasinli, Türker; Eroğlu, Ahmet Emin; Shahwan, TalalThe usage of a variety of sorbents has been shown as promising matrix removal/preconcentration strategies for the determination of rare earth elements (REEs) in various natural water samples by inductively coupled plasma atomic emission spectrometry (ICP-AES). The sorption efficiency of various zeolites (clinoptilolite, mordenite, zeolite Y, zeolite Beta), ion-exchangers (Amberlite CG-120, Amberlite IR-120, Rexyn 101, Dowex 50W X18) and chelating resins (Muromac, Chelex 100, Amberlite IRC-718) towards REEs was investigated in terms of solution pH, shaking time and sorbent amount. The results have shown that most of the materials can take up REEs at a wide pH range. The experiments were continued with clinoptilolite, zeolite Y and Chelex 100 and it was demonstrated that all three materials displayed very fast kinetics for REE sorption (higher than 96% in 1 min). Desorption from the sorbents was realized with 2.0 M HNO3 for clinoptilolite and 0.1 M HNO3 for zeolite Y and Chelex 100. Only the lower concentration range (0.01–2.0 mg l−1) of matrix-matched standards were used in quantitation although the calibration graphs were linear at least up to 10.0 mg l−1 for all REEs studied. The limit of detection (3 s) without preconcentration was 0.1, 1.0, and 0.2 μg l−1 for Eu, La, and Yb, respectively. The validity of the method with the selected sorbents was checked through spike recovery experiments.Article Citation - WoS: 43Citation - Scopus: 47Aas, Xrpd, Sem/Eds, and Ftir Characterization of Zn2+ Retention by Calcite, Calcite–kaolinite, and Calcite–clinoptilolite Minerals(Elsevier Ltd., 2005) Shahwan, Talal; Zünbül, Banu; Tunusoğlu, Özge; Eroğlu, Ahmet EminIn this study, the sorption behavior of Zn2+ on calcite, kaolinite, and clinoptilolite, in addition to mixtures of calcite with kaolinite and clinoptilolite, was investigated at various loadings and mixture compositions using atomic absorption spectroscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy, X-ray powder diffraction, and Fourier transform infrared techniques. According to the obtained results, within the experimental operating conditions, the sorption capacity was enhanced with increasing amount of calcite in both types of mixtures. Under neutral–alkaline pH conditions and high loadings, the order of Zn2+ retention was observed as calcite > clinoptilolite > kaolinite. The experiments on the retention of Zn2+ by pure calcite under conditions of oversaturation showed that the uptake process proceeds via an initial adsorption mechanism (possibly ion-exchange type) followed by a slower mechanism that leads to the overgrowth of the hydrozincite phase, Zn5(OH)6(CO3)2.