Yazar "Bulut, Yasemin" seçeneğine göre listele
Listeleniyor 1 - 16 / 16
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe ADSORPTION OF HEAVY METAL IONS BY POPLAR SAWDUST(Editura Acad Romane, 2007) Bulut, Yasemin; Yokus, BeranDecontamination of synthetic Ni(II), Cd(II) and Pb(II) Solutions using poplar sawdust Was investigated. Batch sorption studies have been carried Out to determine the effect of contact time, temperature and initial Concentration of heavy metal ions (HMI) on adsorption. Equilibrium time was found to be around 60 min. Pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to fit the experimental data. Adsorption isotherms showed that HMI adsorption on sawdust deviated from the Freundlich and Langmuir equations. The Freundlich and Langmuir constants were calculated at different temperatures (25, 45 and 60 degrees C). Thermodynamic parameters, Such as free energy, entropy and enthalpy changes for the adsorption of heavy metal ions have been also Computed and discussed. In addition, the adsorption competition of Ni(II), Cd(II) and Pb(II) ions was determined from the A% values obtained from double and triple mixtures of these ions. Ion exchange is probably one of the major adsorption mechanisms for binding divalent metal ions to poplar sawdust.Öğe Adsorption of Methylene Blue from Aqueous Solution by Crosslinked Chitosan/Bentonite Composite(TAYLOR & FRANCIS INC, 530 CHESTNUT STREET, STE 850, PHILADELPHIA, PA 19106 USA, 2015) Karaer, Hatice; Bulut, YaseminThis article reports the application of a crosslinked chitosan/bentonite composite as adsorbent for the removal of a cationic dye, methylene blue (MB), from aqueous solution. Batch experiments were conducted to study the effects of contact time, initial concentration of adsorbate (50-200 mgL(-1)), temperature (298-313 K), agitation speed (90-150 rpm), and pH (2-10) on adsorption. The equilibrium experimental data were analyzed by the Freundlich and Langmuir models. The kinetic data obtained with different initial concentration and temperature were analyzed using a pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations. Maximum adsorption capacity (Q(m)) was calculated at different temperatures (298, 308, and 313 K) as 95.24, 97.09, and 142.86 mg g(-1), respectively. The results showed that this novel adsorbent had a high adsorption capacity, making it suitable for use in the treatment MB-enriched wastewater.Öğe Adsorption of Ni(II) from aqueous solution by Bacillus subtilis(Taylor & Francis Inc, 2012) Bulut, Yasemin; Gul, Ayten; Baysal, Zubeyde; Alkan, HuseyinThis work reports the application of Bacillus subtilis as adsorbent for the removal of Ni(II) from aqueous solution. Batch experiments were conducted to study the effects of several parameters such as, contact time, initial concentration of adsorbate (25-200 mg L-1), temperature (298-318 K), and adsorbent dose (0.05-0.4 g) on Ni(II) adsorption. Equilibrium adsorption isotherms and kinetics were also investigated. The equilibrium experimental data were analyzed by Freundlich and Langmuir models. The kinetic data obtained with different initial concentration and temperature were analyzed using a pseudo-first-order, pseudo-secondorder, and intraparticle diffusion equations. The results showed that this novel adsorbent had a high adsorption capacity, making it suitable for use in the treatment of Ni(II)-enriched wastewater.Öğe Adsorption studies on ground shells of hazelnut and almond(Elsevier Science Bv, 2007) Bulut, Yasemin; Tez, ZekiAdsorption behaviour of Ni(II), Cd(II) and Pb(II) from aqueous solutions by shells of hazelnut and almond were investigated. The structural properties and surface chemistry of the shells were characterized using sorption of nitrogen and Boehm titration. The equilibrium time was found to be 120 min. The equilibrium adsorption capacity of shells were obtained by using linear Langmuir and Freundlich adsorption isotherms. The equilibrium adsorption level was determined to be a function of the solution contact time, concentration and temperature. The thermodynamic parameters have been determined. The negative values of free change (Delta G) indicated the spontaneous nature of the adsorption of Ni(II), Cd(II) and Pb(II) onto shells of hazelnut and almond and the positive values of enthalpy change (Delta H) suggested the endothermic nature of the adsorption process, The best correlation coefficients were obtained for the pseudo second-order kinetic model. Ion exchange is probably one of the major adsorption mechanisms for binding divalent metal ions to the shells of hazelnut and almond. The selectivity order of the adsorbents is Pb(II) > Cd(II) > Ni(II). (C) 2007 Elsevier B.V. All rights reserved.Öğe Çeşitli bitkisel atıklar üzerinde ağır metal adsorpsiyon kinetiği ve dengesinin incelenmesi(2016) Bulut, Yasemin; Pirinççioğlu, NecmettinEndüstriyel aktivitelerin artması ile atık suların, özellikle metal kirliliği içeren suların temizlenmesi endişeleri artmıştır. Metal iyonlarının, sulu çözeltiden ayrılması için kimyasal çöktürme, iyon değiştirme, filtrasyon ve adsorpsiyon gibi bazı yöntemler kullanılmaktadır. Ancak bu yöntemler genellikle pahalıdır. Adsorpsiyon yaygınca kullanılan etkili yöntemlerden biridir. Bununla beraber adsorpsiyonda maliyet önemli bir parametredir. Bu nedenle zararlı atıkların işlenmesi için daha az pahalı olan yerel kaynakların kullanımı çevresel biyoteknolojinin gelişimi için uygundur. Bu çalışmada maliyeti çok düşük olan fındık kabuklan, badem kabuklan, kavak ve,, ceviz ağacı talaşlan ile bu adsorplayıcıların formaldehit ile modifiye edilmiş halleri adsorplayıcı olarak kullanılarak sulu çözeltiden Ni(II), Cd(II) ve Pb(II) iyonları uzaklaştınldı. Belirli miktardaki ham ve modifiye adsorplayıcılar başlangıç derişimi belli metal iyonu çözeltisinin belli miktan ile karıştmlarak, zamanla denge derişimindeki azalma ölçülerek kinetik veriler elde edildi ve denge süresi belirlendi. Bu kinetik veriler psödo-birinci ve psödo-ikinci hız mertebe modellerinde değerlendirilerek adsorpsiyon hız sabitleri hesaplandı. Aynca gözenek difüzyon'vc parçacık içi kütle difüzyon katsayıları hesaplandı. Üç farklı sıcaklıkta ham ve modifiye adsorplayıcılann sabit miktan ile derişimleri farklı bir seri çözelti belirlenen denge süresince çalkalandı ve denge süresi sonunda çözeltiler analiz edilerek denge derişimleri belirlendi. Denge derişimine karşı birim miktar adsorplayıcı üzerinde adsorplanan metal iyonu miktarı grafiğe geçirilerek adsorpsiyon izotermleri elde edildi. Adsorpsiyon izoterm verileri Freundlich ve Langmuir izoterm modellerinde değerlendirilerek adsorpsiyon izoterm sabitleri ve yine bu veriler yardımı ile adsorpsiyon denge sabiti (Ko) bulunup serbest enerji değişimi (AG), entalpi değişimi (AH) ve entropi değişimi (AS) gibi termodinamik parametreler hesaplandı. Aynca Ni(II), Cd(II) ve Pb(Il) iyonlannın, ikili ve üçlü karışım halindeki % A değerleri belirlenerek bu metal iyonlannın adsorpsiyon rekabeti incelenmiştir.Öğe Enantioselective transport and liquid-liquid extraction of amino acids as their potassium and sodium salts by optically active diaza-18-crown-6 ethers(Wiley, 2004) Demirel, Nadir; Bulut, Yasemin; Hoşgören, Halil; 0000-0002-8571-5552Complexation of amino acids as their sodium and potassium salts by optically active diaza crown ethers has been investigated in transport across bulk liquid membranes containing the carriers and in extraction experiments. The observed enantio selectivity was achieved by (noncovalent) steric and repulsive interactions between the side arm of the crown ether and functional group(s) of the amino acids. The highest enantio selectivity was observed in the case of tryptophan. (C) 2004 Wiley-Liss, Inc.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 Equilibrium and thermodynamic studies on biosorption of Pb(II) onto Candida albicans biomass(Elsevier Science Bv, 2009) Baysal, Zuebeyde; Cinar, Ercan; Bulut, Yasemin; Alkan, Hueseyin; Dogru, MehmetBiosorption of Pb(II) ions from aqueous solutions was studied in a batch system by using Candida albicans. The optimum conditions of biosorption were determined by investigating the initial metal ion concentration, contact time, temperature, biosorbent dose and pH. The extent of metal ion removed increased with increasing contact time, initial metal ion concentration and temperature. Biosorption equilibrium time was observed in 30 min. The Freundlich and Langmuir adsorption models were used for the mathematical description of biosorption equilibrium and isotherm constants were also evaluated. The maximum biosorption capacity of Pb(II) on C. albicans was determined as 828.50 +/- 1.05, 831.26 +/- 1.30 and 833.33 +/- 1.12 mg g(-1), respectively, at different temperatures (25, 35 and 45 degrees C). Biosorption showed pseudo second-order rate kinetics at different initial concentration of Pb(II) and different temperatures. The activation energy of the biosorption (E-a) was estimated as 59.04 kJ mol(-1) from Arrhenius equation. Using the equilibrium constant value obtained at different temperatures, the thermodynamic properties of the biosorption (Delta G degrees, Delta H degrees and Delta S degrees) were also determined. The results showed that biosorption of Pb(II) ions on C. albicans were endothermic and spontaneous. The optimum initial pH for Pb(II) was determined as pH 5.0. FTIR spectral analysis of Pb(II) adsorbed and unadsorbed C. albicans biomass was also discussed. (C) 2008 Elsevier B.V. All rights reserved.Öğe Immobilization of ?-amylase via adsorption onto bentonite/chitosan composite: Determination of equilibrium, kinetics and thermodynamic parameters(Wiley-V C H Verlag Gmbh, 2014) Baysal, Zübeyde; Bulut, Yasemin; Yavuz, Murat; Aytekin, ÇetinImmobilization of -amylase onto bentonite/chitosan (BC) composite was studied via adsorption. The composite was characterized by FTIR, SEM, and surface area measurements. The effect of different factors such as, pH, temperature, initial enzyme concentration, and various thermodynamic parameters was determined. The maximum -amylase adsorption capacity of the BC composite was determined as 64mg/g at 0.8mg/mL enzyme concentration. The activity of the immobilized enzyme was measured under varying experimental conditions. The highest enzyme activity for free and immobilized enzyme was determined at 30 and 35 degrees C in 0.1M phosphate buffer at pH 7.0. The effect of substrate concentration on enzyme activity of free and immobilized enzymes showed a good fit to the Lineweaver-Burk plots. Michaelis constant, K-m, for the immobilized -amylase was found to be higher than for the free enzyme. The adsorption isotherm was modeled by the Langmuir equation.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 KINETICS OF ADSORPTION OF ACID RED 1 ONTO CHITOSAN AND CROSS-LINKED CHITOSAN FROM AQUEOUS SOLUTION(Bilal GÜMÜŞ, 2017) Yıldırım, Ayfer; Bulut, YaseminChitosan(CS) and crosslinked-Chitosan (CCS) (Chitosan+Glutaraldehite) were utilized as adsorbents to remove acid red1(AR1) from aqueous solution by adsorption. Batch experiments were conducted to study initial concentration of adsorbate and temperature on dye adsorption. The kinetic data obtained from different batch experiments were analyzed using pseudo first-order and pseudo second-order and Weber-Morris equations, and the rate constants of first-order adsorption (kpf), the rate constants of second-order adsorption (kps) and intraparticle diffusion rate constants (kid) at these concentrations and temperatures were calculated, respectively.Öğe Removal of heavy metals from aqueous solution by sawdust adsorption(Science Press, 2007) Bulut, Yasemin; Tez, ZekiThe adsorption of lead, cadmium and nicel from aqueous solution by sawdust of walnut was investigated. The effect of contact time, initial metal ion concentration and temperature on metal ions removal has been studied. The equilibrium time was found to be of the order of 60 min. Kinetics fit pseudo first-order, second-order and intraparticle diffusion models, hence adsorption rate constants were calculated. The adsorption data of metal ions at temperatures of 25, 45 and 60 degrees C have been described by the Freundlich and Langmuir isotherm models. The thermodynamic parameters such as energy, entropy and enthalpy changes for the adsorption of heavy metal ions have also been computed and discussed. Ion exchange is probably one of the major adsorption mechanisms for binding divalent metal ions to the walnut sawdust. The selectivity order of the adsorbent is Pb(II)approximate to Cd(II)> Ni(II). From these results, it can be concluded that the sawdust of walnut could be a good adsorbent for the metal ions from aqueous solutions.Öğe Removal of Methylene Blue from Aqueous Solution by Crosslinked Chitosan-g-Poly(Acrylic Acid)/Bentonite Composite(Taylor & Francis Inc, 2015) Bulut, Yasemin; Karaer, HaticeA new crosslinked chitosan-g-poly (acrylic acid)/bentonite composite (CS-g-PAA/BT) was prepared and used for the removal of methylene blue (MB). CS-g-PAA/BT was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The water absorbency for CS-g-PAA/BT was found to be 93 and 50 g H(2)Og(-1) in distilled water and 0.2% NaCl, respectively. The results showed that the adsorption of the MB on the CS-g-PAA/BT was effected by the initial dye concentration, the initial pH value, as well as the temperature. Both kinetics and thermodynamic parameters of the adsorption process were estimated. These data indicated an endothermic spontaneous adsorption process that kinetically followed the second-order adsorption process. Equilibrium experiments fitted well the Langmuir isotherm model, and the maximum monolayer adsorption capacity for the MB was 2000-2500 mg g(-1) at 298-313 K. The results of this study implied that CS-g-PAA/BT can be used a promising adsorbent for the removal of MB from wastewater.Öğe Removal of methylene blue from aqueous solutions onto Bacillus subtilis: determination of kinetic and equilibrium parameters(Desalination Publ, 2013) Ayla, Ayseguel; Cavus, Aynur; Bulut, Yasemin; Baysal, Zubeyde; Aytekin, CetinIn the present study, Bacillus subtilis, a Gram-positive bacteria, was used in dried biomass form as biosorbent for removal of methylene blue (MB) from aqueous solutions. Batch adsorption tests were performed at different contact times, temperatures, pH, adsorbent doses, and initial dye 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 biosorption capacity was found to be 169.49, 178.57, and 181.82mgg(-1) at 298, 308, and 318K, respectively. The adsorption kinetics of MB could be described by the pseudo-second-order reaction model. The activation energy of the biosorption (E-a) was determined as 11.30kJmol(-1) at initial concentration of 50mgL(-1). Free energy of adsorption (G degrees), enthalpy (H degrees), and entropy (S degrees) changes were calculated to predict the nature of adsorption. The estimated values for G degrees were -21.22, -22.02, and -23.01kJmol(-1) at 298, 308, and 318K, respectively. The enthalpy changes and entropy of adsorption were 5.47kJmol(-1) and 89.43Jmol(-1), respectively. The experimental data obtained in the present study indicate that B. subtilis is a suitable and inexpensive adsorbent which can be used for dye removal in wastewater treatment processes.Öğe Synthesis of clay-based superabsorbent composite and its sorption capability(Elsevier Science Bv, 2009) Bulut, Yasemin; Akcay, Guelten; Elma, Duygu; Serhatli, I. ErsinA novel superabsorbent composite was synthesized by copolymerization reaction of partially neutralized acrylic acid (AA) on bentonite micropowder using N,N'-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator in aqueous solution. The superabsorbent composite (SAC) was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The water retention test of SAC was also performed. The water absorbency of SAC synthesized was found to be 352 and 110 g H(2)Og(-1) in distilled water and 0.2% NaCl, respectively. Sorption capacity of SAC was investigated for heavy metal ions (HMI) using Langmuir and Freundlich model of adsorption. The maximum adsorption capacity (Q(m)) of HMI onto the bentonite-based SAC from their solution was 1666.67, 270.27, 416.67 and 222.22 mg g(-1) for Pb(II). Ni(II), Cd(II) and Cu(II), respectively. All results suggested that SAC offers excellent potential for HMI removal from contaminated water. (C) 2009 Elsevier B.V. All rights reserved.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.
