Yazar "Akba, Osman" seçeneğine göre listele
Listeleniyor 1 - 17 / 17
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Application of Modified BCR Sequential Extraction Method for the Fractionation and ICP-OES Determination of Copper in Asphaltite Combustion Waste(Atomic Spectroscopy Press Ltd, 2013) Aydin, Firat; Gunduz, Beniz; Aydin, Isil; Akba, Osman; Saydut, Abdurrahman; Hamamci, CandanAsphaltite is derived from petroleum-origin solid fossil fuel. It contains many elements in different forms which may change during the combustion process. This study presents a modified BCR sequential extraction method for the fractionation of copper (Cu) in asphaltite combustion waste (ACW) into four forms (exchangeable, reducible, oxidizable, and residual) and determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The 327.393 nm line was used because it offers highest detectability and is free from major spectral interferences. A two-stage microwave acid digestion program was used for preparation of the samples. The total Cu concentration in the ACW was 104.56 mg kg(-1) dry weight (d.w). The most abundant copper fraction in the studied ACW samples was found as residual fraction of Cu (59.94 mg kg(-1) d.w.). The relative abundances of the remaining Cu fractions in ACW were as follows: exchangeable + water- and acid-soluble (19.07 mg kg(-1) d.w.) > oxidizable (17.49 mg kg(-1)' d.w.) > reducible (7.65 mg kg(-1) d.w.). The results were found to be in good agreement with the certified values. The advantages of the technique include a high degree of automation, good reproducibility, and short analysis time, which makes it the method of choice for the fractionation of Cu.Öğe BIOACCUMULATION OF COPPER, CADMIUM AND NICKEL IN DUCKWEED (Lemna trisulca)(Parlar Scientific Publications (P S P), 2015) Kara, Yesim; Akba, OsmanDuckweeds are small free-floating plants often farming dense mats on the surface of stillor slow flowing water. Lemna trisulca (Duckweed) was examined for its ability to remove heavy metals. In laboratory conditions, plants were exposed to the copper, cadmium and nickel concentrations of 1.0, 3.0, 5.0 and 7.0 mg L-1 in certain periods (24, 48, 72 and 96 hours). The accumulation levels of metals in plants depending on different time and concentrations were investigated by using atomic absorption spectrometer. The results on bioaccumulation rates of Ni, Cd and Cu ions in Duckweed showed that the plant was able to remove the heavy metals. The maximum BCF values obtained were 541 for Cd, 848 for Cu and 1867 for Ni. Among the metals used, Ni was found to be accumulated at higher levels depending on the metal concentrations and time periods.Öğe Chemical Characteristics of Settled Particles during a Dust-Storm(Hard, 2012) Aydin, Firat; Aydin, Isil; Erdogan, Sait; Akba, Osman; Isik, Birgul; Hamamci, CandanMajor synoptic systems bring desert dust from Arabia and the Sahara to Anatolia, Turkey. A study of particulate matter (PM) associated metal content such as As, Al, Cr, Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Se, Sn, and Zn, etc., has been carried out for Diyarbakir, SE Anatolia, Turkey. Results show that the PM10 levels during a dust storm were much higher than in a non-dust-storm period and that four metals (Fe, Al, Cr, Mn) were dominant in settled particles. This research does not only provide background data for air quality management, but also provides valuable information about the chemical composition of the particles.Öğe Comparison of microwave and conventional digestion of copper ores and determination of heavy metals by ICP-AES(Asian Journal Of Chemistry, 2006) Akba, Osman; Ozturk, Gulsen; Biricik, Nermin; Gumgum, BahattinThis paper summarizes the results obtained in applying conventional and microwave digestion techniques to Maden and Hazro copper materials for subsequent analysis by inductively coupled plasma (ICP-AES).Öğe Content and Mobility Behavior of Iron and Manganese in Asphaltite Burning Residue Using ICP-OES(Atomic Spectroscopy Press Ltd, 2014) Aydin, Isil; Gunduz, Beniz; Aydin, Firat; Akba, Osman; Saydut, Abdurrahman; Hamamci, CandanThe determination of inorganic pollutants leaching from solid waste, such as coal, asphaltite, oil shale, and ash, is an important topic for industrial applications and solid waste management. This study presents the concentration and fractionation of iron (Fe) and manganese (Mn) in asphaltite burning residue (ABR) and their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). A modified Tessier sequential extraction method was used for the fractionation of Fe and Mn in four forms (exchangeable, carbonates, bound to organic and sulfide, and residual content). Investigations on the Fe and Mn chemical fractions and their environmental mobility in ash solution systems were carried out. It was found that Mn in ABR (from Harbul-Silopi, Turkey) occurs in the following fractions: exchangeable (13.56%), associated with carbonates (28.94%), associated with organic matter and sulfides (17.48%), and residual content (40.08%). Fe occurs in the following fractions: exchangeable (11.11%), carbonates (27.68%), organic matter and sulfides (23.39%), and residual content (37.82%). Among these fractions, the exchangeable and carbonate-bound fractions are unstable and prone to leach out, while the organic matter-bound fractions and the residual fractions are considered to be relatively stable and of low bioavailability. Thw mobility fractions of Fe contain 38.79% and of Mn contain 42.50% of their total concentration in ABR under normal environmental conditions.Öğe Heteropoli asit ve komplekslerin spektroskopik incelenmesi ve analitik uygulamalarının araştırılması(2018) Akba, Osman; Gümgüm, BahattinHeteropoli asit ve komplekslerinin spektroskopik özellikleri TGA, İR, XRD, UV, SEM fotoğraflama teknikleri ile incelendi. İncelenen heteropoli asitler, düşük düzeyde özgül yüzey alanı göstermektedir. Bunların katalitik aktiflikleri gözeneklilikten değil, çok düşük birincil parçacıkların dış yüzeylerinden kaynaklanmaktadır. Heteropoli asit ve komplekslerinin TGÂ incelemeleri sonucunda genellikle polianyonun 400 °C'ye kadar korunduğu tespit edilmiştir. Heteropoli asitler ile 03P, 03N, Et3N ve Büt3N arasındaki reaksiyonlarda ele geçen ürünlerin İR, TGA, element analizleri, UV spektrumları alınıp incelendiğinde, heteropoli asitlerle 03P, 0vN, Et?N ve Büt?N arasında normal nötralleşme reaksiyonlarından beklenen ürünler dışında da ürünlerin oluştuğu saptandı. Heteropoli asitlerin 0?P, 0.*N, EuN ve metilen mavisi gibi azotlu bileşikler ile değişik renklerde çökelekler oluşturdukları ve bunların I0"'-10"5 M konsantrasyonlarında tayin edilebilecekleri tespit edildi. Heteropoli asitlerin kataliz uygulamaları kısmen çalışıldı. Heteropoli asit varlığında izobüten oluşumu ve 2-hidroksipropil t-bütil eterin oluşum reaksiyonları incelendi.Öğe Katalizör olarak kullanılabilecek heteropoli asit tuzlarının hazırlanması(1993) Yurdakoç, M. Kadir; Güzel, Fuat; Tez, Zeki; Gümgüm, Bahattin; Akba, OsmanHPA'lann heterojen ve homojen katalizör olarak kullanılmaları çeşitli organik bileşiklerin sentezlenmesi açısından yeni bir çığır açmıştır. 1982 yılında HPA'nın katalizörlüğünde metakrolein'den metakrilik asit eldesinin endüstriyel ölçekte gerçekleştirilmesiyle başlayan bu tür uygulamalar, başta Japonya ve Rusya olmak üzere gelişmiş ülkelerde bu konudaki araştırmaları hızlandırmıştır. Bu proje çalışmasında, hazırlanan çeşitli türde heteropoli asit ve tuzlarının TGA incelemeleri yoluyla formülasyon doğrulama ve yapısal kararlılık belirlemeleri yapılmış; BET-tek nokta N2 gazı adsorpsiyonu yoluyla özgül yüzey alanları belirlenmiş; SEM fotoğrafları yoluyla amorf ya da kristal durumları görüntülenmeye çalışılmış; uygun indikatör çözeltileri yanında n-bütil amin titrasyonu yöntemiyle bu katıların asitlik şiddetleri belirlenmiş ve XRD, EDX ve FTIR incelemelerinden de elde edilen katılardaki karakteristik elementlerin ağırlık otanları ve safsızlık durumları belirlenmeye çalışılmıştır. Bu çalışmanın uzantısında ise dehidratasyon, dehidrojehasyon ve oksidasyon reaksiyonlarına birer örnek teşkil edecek şekilde uygun heterojen ve homojen model test reaksiyonları eşliğinde, elde edilen HPA ve tuzlarının katalitik özellikleri ve reaksiyon kinetiksel parametreleri belirlenmeye çalışılacaktır.Öğe Major and Trace Element Contamination of Short-Term Snow Cover During and After a Dust Storm and Analysis by ICP-OES(Atomic Spectroscopy Press Ltd, 2013) Akba, Osman; Kilinc, Ersin; Aydin, Isil; Erdogan, Sait; Aydin, Firat; Duz, M. Zahir; Hamamci, CandanThe levels of major and trace elements are key data for evaluating the toxicity of potential particulate matter and for identifying pollution sources. From this point of view, snow is considered an ideal matrix to observe deposition from the atmosphere due to environmental and anthropogenic activities. This work has demonstrated that major and trace element levels of Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Se, Sn, and Zn were found in snow precipitation sampled during and after a dust storm in and around Diyarbakir city, SE Anatolia, Turkey. A simple methodological approach consisting of surface snow sampling and analysis by ICP-OES provides information about the spatial distribution and temporal evolution of atmospheric precipitation. The concentrations of toxic metals were found at high levels and are therefore a threat to human health. In particular, the concentrations for Fe and Al were significantly higher than for the other elements.Öğe Methyl ester of peanut (Arachis hypogea L.) seed oil as a potential feedstock for biodiesel production(Pergamon-Elsevier Science Ltd, 2009) Kaya, Canan; Hamamci, Candan; Baysal, Akin; Akba, Osman; Erdogan, Sait; Saydut, AbdurrahmanThe peanut (Arachis hypogea L.) seed oil was extracted from the seeds of the peanut that grows in SE Anatolia of Turkey. Oil was obtained in 50 wt/wt.%, by solvent extraction. Peanut (A. hypogea L) seed oil was investigated as an alternative feedstock for the production of a biodiesel fuel. Biodiesel was prepared from peanut by transesterification of the crude oil with methanol in the presence of NaOH as catalyst. A maximum oil to ester conversion was 89%. The viscosity of biodiesel oil is nearer to that of petroleum diesel and the calorific value is about 6% less than that of diesel. Peanut seed oil have about 8.3% less heating value than that of diesel oil due to the oxygen content in their molecules. The quality of biodiesel is most important for engine part of view and various standards have been specified to check the quality. The important properties of peanut oil and its methyl ester (biodiesel) such as density, kinematic viscosity, flash point, iodine number, neutralization number, pour point, cloud point, cetane number are found out and compared to those of no, 2 petroleum diesel, ASTM and EN biodiesel standards. The comparison shows that the methyl ester has relatively closer fuel properties to diesel than that of raw peanut seed oil. (C) 2008 Elsevier Ltd. All rights reserved.Öğe Preparation and solvent extraction of nickel complex of O, O'-dinonyldithiophosphate and its application to spectrophotometric determination of nickel in sediment samples(Wiley-V C H Verlag Gmbh, 2006) Gümgüm, Bahattin; Biricik, Nermin; Baysal, Akın; Akba, Osman; Öztürk, Gülşen; 0000-0001-7294-6792Nickel complex of O, O'-dinonyldithiophosphoric acid was prepared and characterised. Solvent extraction of nickel dinonyldithiophosphate[Ni(DNDTP)(2)] from acidic aqueous solutions into different organic phases was investigated and concentration of nickel was determined spectrophotometrically. A simple and selective spectrophotometric method was developed and applied to sediment samples.Öğe Relationship between wintertime atmospheric particulate matter and meteorological conditions in Diyarbakir (Turkey)(Asian Journal Of Chemistry, 2007) Erdogan, Sait; Baysal, Akin; Akba, Osman; Merdivan, Melek; Hamamci, CandanThis paper reported the changes in pollution concentration in Diyarbakir, South east region of Turkey in the winter half of the year from 1986 to 2004 and describes the relationships with meteorology. Particulate matter (PM),, is used as the example Pollutant. Decrease in air pollution since 1994 was observed due to air pollution control and management strategies. The winters of 1988-1989, 1989-1990, 1990-1991, 1991-1992 and 1992-1993 were especially harsh in the number of pollution episodes. Linear regression results show that relative humidity and temperature provide the relationship with PM10 concentration.Öğe Simultaneous Determination of Transition Metals in Hazelnuts (Corylus avellana L.) by ICP-OES(Atomic Spectroscopy Press Ltd, 2014) Celik, K. Serdar; Aydin, Firat; Duz, M. Zahir; Aydin, Isil; Erdogan, Sait; Akba, Osman; Hamamci, CandanHeavy metal concentrations in foods are of interest because of their essential or toxic nature. The present work reports the results obtained for the simultaneous determination of essential and/or toxic metals (Cd, Co, Cr, Cu, Fe, Ni, Pb, Zn) in 24 hazelnut samples by inductively coupled plasma optical emission spectrometry (ICP-OES) after sample digestion using a diluted oxidant mixture in a closed-vessel microwave system. The obtained results (mean in mg/kg) were: Co 1.15, Cr 1.92, Cu 17.96, Fe 489, Ni 4.76, and Zn 85. The concentrations of Cd and Pb were below the detection limits and are below the daily intake recommended by the international organizations (WHO). Therefore, it can be stated that hazelnuts are safe for public consumption. The macro and micro nutrient ranges in hazelnut (Corylus avellana L.) did not exceed the dietary reference intake (DRI).Öğe Simultaneous Multielement Determination of Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sn, and Zn in Bulgur Wheat by ICP-OES(Atomic Spectroscopy Press Ltd, 2015) Erdogan, Sait; Aydin, Isil; Duz, M. Zahir; Aydin, Firat; Celik, K. Serdar; Akba, Osman; Hamamci, CandanBulgur is one of the oldest cereal-based foods. This study explains the simultaneous determination by the proposed method for toxic elements such as Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sn, and Zn in bulgur by ICP-OES following digestion in a closed-vessel microwave system. The ICP-OES method is used because it is precise, rapid, simple, and accurate for the determination of 12 metals. The technique can be considered useful for the routine analysis of multi-elements in cereals as well as for quality control purposes. The obtained results in the bulgur samples (mean in mg kg(-1)) were: Al 0.81, Cr 0.19, Cu 3.80, Fe 26.75, Mn 13.60, Ni 0.25, Pb 0.23, Sn 0.17, and Zn 14.30. The concentrations of As, Cd, and Hg were below the detection limits. A certified reference material was used to verify the accuracy of the studied method. The results were in good agreement with the certified values. The toxic metal concentrations are low and the obtained values are suitable for daily intake. The macro and micro nutrient ranges in bulgar wheat did not exceed the dietary reference intake (DRI). The bulgur produced in Turkey has very low levels of toxic metals, is safe for human consumption, and is a highly nutritional and healthy food source. Bulgur wheat is, therefore, safe for public consumption.Öğe Synthesis and characterization of new bis(diphenylphosphino)aniline ligands and their complexes: X-ray crystal structure of palladium(II) and platinum(II) complexes, and application of palladium(II) complexes as pre-catalysts in Heck and Suzuki cross-coupling reactions(Pergamon-Elsevier Science Ltd, 2009) Aydemir, Murat; Durap, Feyyaz; Baysal, Akin; Akba, Osman; Gumgum, Bahattin; Ozkar, Saim; Yildirim, Leyla TatarTwo new bis(diphenylphosphino)isopropylphenylamines, (PPh2)(2)N-C6H4-CH(CH3)(2), having the isopropyl substituent at the carbon atom 2 (1) or 4 (2), were prepared by the aminolysis of chlorodiphenylphosphine with isopropyl substituted aniline at the ortho- or para-position, respectively, under anaerobic conditions. Oxidation of 1 and 2 with either aqueous hydrogen peroxide, elemental sulfur or grey selenium in thf gave the corresponding oxides, sulfides and selenides (Ph2P=E)(2)N-C6H4-CH(CH3)(2), where E = O, S or Se, respectively. The palladium and platinum complexes [M{(Ph2P)(2)N-C6H4-CH(CH3)(2))Cl-2] (M = Pd, Pt) and the copper complex [Cu((Ph2P)(2)N-C6H4-CH(CH3)(2))(2)]PF6 were isolated from the reaction of the bis(phosphino)anilines with MCl2(cod) or [Cu(CH3CN)(4)]PF6, respectively. The new compounds were characterized by NMR, IR spectroscopy and elemental analysis. Furthermore, the solid-state structures of two representative complexes were determined using single crystal X-ray diffraction analysis. The compounds of palladium (1d) and platinum (1e), both mononuclear complexes, crystallize in the monoclinic P2(1)/c space group. In both compounds the metal ion has a distorted square-planar coordination geometry. The structural properties of complexes Id and le in the solid state are very similar. The palladium complexes were also tested for their catalytic activities in C-C coupling reactions. (C) 2009 Elsevier Ltd. All rights reserved.Öğe Synthesis and characterization of polyoxometallate compounds of amine and phosphine with molybdovanadophosphoric acid in Keggin type(Asian Journal Of Chemistry, 2006) Gumgum, Bahattin; Akba, Osman; Baysal, Akin; Hamamci, CandanFour novel compounds were synthesized by the reaction of tertiary amines (triphenyl amine, triethyl amine, tributyl amine) and triphenyl phosphine with freshly prepared molybdovanadophosphoric acid (H4PMO11VO40 center dot 32H(2)O). The products were characterized by elemental analysis, spectroscopic techniques (UV, IR, ICP-AES) and thermal analysis (TG/DTA). The experimental data indicated that the synthesized compounds retain the Keggin structure.Öğe Synthesis and characterizations of N,N,N?,N?-tetrakis (diphenylphosphino)ethylendiamine derivatives: Use of palladium(II) complex as pre-catalyst in Suzuki coupling and Heck reactions(Elsevier Science Sa, 2009) Akba, Osman; Durap, Feyyaz; Aydemir, Murat; Baysal, Akin; Guemguem, Bahattin; Oezkar, SaimOxidation of N,N,N',N'-tetrakis(diphenylphosphino)ethylendiamine (1) with elemental sulfur and selenium gives the corresponding sulfide and selenide, respectively, [(Ph2P(E))(2)NCH2CH2N(P(E)Ph-2)(2)] (E: S 1a, Se 1b). Complexes of 1 [(M2Cl4){(Ph2P)(2)NCH2CH2N(PPh2)(2)}] (M: Ni(II) 1c, Pd(II) 1d, Pt(II) 1e) were prepared by the reaction of 1 with NiCl2 or [MCl2(COD)] (M = Pd, Pt). The new compounds were characterized by NMR, IR spectroscopy and elemental analysis. The catalytic activity of Pd(II) complex 1d was tested in the Suzuki coupling reaction and Heck reaction. The palladium complex 1d catalyses the Heck reaction between styrene and aryl bromides as well as Suzuki coupling reaction between phenylboronic acid and arylbromides affording stilbenes and biphenyls in high yield, respectively. (C) 2008 Elsevier B.V. All rights reserved.Öğe Synthesis, characterization, crystal and molecular structure of diphenyloxophosphinoethylenediamines(Pergamon-Elsevier Science Ltd, 2006) Guemguem, Bahattin; Akba, Osman; Durap, Feyyaz; Yildirim, Leyla Tatar; Uelkue, Dincer; Oezkar, SaimBis-, tris- and tetrakis(diphenyloxophosphino)ethylenediamine compounds can be synthesized starting with ethylenediamine and chlorodiphenylphosphine. Bis(diphenylphosphino)ethylenediamine and tris(diphenylphosphino)ethylenediamine are formed as intermediates and can be oxidized to the respective phosphine oxides by oxygen dissolved in the reaction solution, while tetrakis(diphenylphosphino)ethylenediamine is less liable to oxidation and its oxidation requires a stronger oxidizing agent such as hydrogen peroxide. All the three phosphine oxides and tetrakis(diphenylphosphino)ethylenediamine can be isolated as analytically pure solid materials and are fully characterized by elemental analysis, MS and NMR spectroscopies. The crystal and molecular structure of tris(diphenylphosphino)ethylenediamine was elucidated by single crystal X-ray diffraction analysis. (C) 2006 Elsevier Ltd. All rights reserved.
