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Öğe Adsorption of some heavy metal ions from aqueous solution by activated carbon and comparison of percent adsorption results of activated carbon with those of some other adsorbents(Scientific Technical Research Council Turkey, 2000) Uzun, I; Güzel, FIn this study, removal of some heavy metals ions (Mn2+, Fe2+, Ni2+ and Cu2+) from aqueous solution by adsorption was investigated. For this purpose, high-grade MnSO4.H2O,FeSO4. 7H(2)O,NiSO4. 7H(2)O and CuSO4. 5H(2)O were used as heavy metal samples. The commercial activated carbon (Merck 2514), chitosan and agar were used as adsorbents. The pH of each solution was not controlled. This is because the net interaction between the adsorbent and the heavy metal could be disturbed by the buffer solution. Therefore, all experiments were carried out in a pH range from 5.3 to 5.5. The equilibrium adsorption contact times were determined for M - 2514. The adsorption rate constants were determined from obtained kinetics curves suitable for first degree of rate kinetics. Adsorption isotherms of heavy metals on M - 2514 from aqueous solution were determined. These adsorption isotherms were seen to be consistent with Freundlich's adsorption isotherm. k and n constants were determined from Freundlich's linear equation. In addition, M - 2514, chitosan and agar were compared according to their percent uptake yields of the heavy metals.Öğe Characterization of the micropore structure of activated carbons by adsorptions of nitrogen and some hydrocarbons(Marcel Dekker Inc, 1999) Güzel, FIn the present study the effects of the duration of carbonization and physical activation properties of activated carbon from vegetable materials were investigated. Peanut shells were used to obtain active carbon. These shells were activated chemically with ZnCl2 and/or CO2 for different times, and the micropore structures of these active carbons were studied by measuring the adsorption isotherms for nitrogen and some hydrocarbons such as benzene, n-butane, isobutane, 2,2-dimethylbutane, and isooctane. As the physical activation time was increased, the primary micropores, which were measured at 0.01 relative pressure, were reduced, and they were replaced by larger secondary and tertiary micropores which were measured at 0.15-0.01 and 0.30-0.15 relative pressures. The ratios of the mesopore volume to the micropore volume also increased as the duration of physical activation increased.Öğe Determination of the micropore structures of activated carbons by adsorption of various dyestuffs from aqueous solution(Scientific Technical Research Council Turkey, 2002) Güzel, F; Uzun, IIn this study, some activated carbons prepared from sour cherry pits under various conditions were investigated, For comparison purposes, the commercial activated carbons Merck-2514 and Merck-2184 were used. The nitrogen adsorption isotherms at 77 K were used as reference for comparison. while p-nitrophenol, methylene blue, orange-II and victoria blue adsorptions were determined from aqueous solution at 298 K. It was clear from the specific surface area values obtained that the bust activated carbon was obtained by activation for 4 hours following the chemical activation. Its adsorption properties are closer to the levels of the Merck commercial carbons. It was concluded that the characterization of microporous structure, and the testing of the removal of organic impurities from aqueous solution for active carbons having high adsorption ability from the gas phase, can generally be carried out by adsorption of organic solutes whose molecular sizes are smaller than the micropore size (1.5 nm) of the adsorbent.Öğe External mass transfer studies during the adsorptions of some dyestuffs and p-nitrophenol onto chitosan from aqueous solution(Tubitak Scientific & Technological Research Council Turkey, 2004) Uzun, I; Güzel, FThe effect of temperature on the adsorptions of some dyestuffs (orange 11 (O-II), crystal violet. (CV) and reactive blue 5 (RB5)] and an ideal adsorbate p-nitrophenol (PNP) by chitosan (Sigma C 36,46) from aqueous solution was investigated. The experimental data related to adsorption isotherms were applied to linear forms of the equations that they fitted, and isotherm constants were calculated. Since the isotherm curves obtained for the adsorptions of O-II and CV by chitosan fitted the Langmuir adsorption isotherm, the Langmuir constants (q(m) and b) related to the adsorption isotherms of these dyestuffs together with their kinetical data at different temperatures were applied to the equation of McKay et, al., and external mass transfer coefficients (k(f))(1) at these temperatures were calculated. In addition. kinetic data obtained for each dyestuff and PNP at different temperatures were applied to a further equation developed by Weber-Mathews, and (k(f))(2) Constants at these temperatures were calculated.Öğe Kinetics and thermodynamics of the adsorption of some dyestuffs and p-nitrophenol by chitosan and MCM-chitosan from aqueous solution(Academic Press Inc Elsevier Science, 2004) Uzun, I; Güzel, FThe effect of initial concentration, temperature, and shaking rate on the adsorption of three dyestuffs [orange II (O-II), crystal violet (CV), and reactive blue 5 (RB5)] and an ideal adsorbate, p-nitrophenol (PNP), by chitosan (Sigma C-3646) and the effect of temperature on the adsorption of O-II and CV by monocarboxymethylated chitosan (MCM-chitosan) were investigated. Kinetic data obtained for the adsorption of each dyestuff and PNP by chitosan and of O-II and CV by MCM-chitosan at different temperatures were applied to the Lagergren equation, and adsorption rate constants (k(ads)) at these temperatures were determined. These rate constants related to the adsorption of O-II and RB5 by chitosan and of O-II by MCM-chitosan were applied to the Arrhenius equation, and activation energies (E-a) were determined. In addition, the isotherms for adsorption, at different temperatures, of each dyestuff and PNP by chitosan and of O-II and CV by MCM-chitosan were also determined. These isothermal data were applied to linear forms of isotherm equations that they fit, and isotherm constants were calculated. Because the isotherm curves obtained for the adsorption of O-II and CV by chitosan and of CV by MCM-chitosan fit the Langmuir adsorption isotherm, b constants were applied to thermodynamic equations, and thermodynamic parameters (DeltaG, DeltaH, and DeltaS) were calculated. Lastly, chitosan and MCM-chitosan were compared with respect to the ability to take up the dyestuffs and PNP. (C) 2004 Elsevier Inc. All rights reserved.Öğe Rate studies on the adsorption of some dyestuffs and p-nitrophenol by chitosan and monocarboxymethylated(mcm)-chitosan from aqueous solution(Elsevier Science Bv, 2005) Uzun, I; Güzel, FIn this study, the effect of temperature on the adsorption of some dyestuffs [orange II (O-II), crystal violet (CV) and reactive blue 5 (RB5)] and p-nitrophenol (PNP) by chitosan and of O-II and CV by modified chitosan [monocarboxymethylated(mcm)-chitosan] from aqueous solution was investigated. Kinetical data related to the adsorptions of each dyestuff and PNP by chitosan and of O-II and CV by mcm-chitosan were applied to Lagergren and Weber-Morris equations, and adsorption rate constants (k(ads)) and pore diffusion rate constants (k(p)) were determined, respectively. In addition, Langmuir isotherm constants with experimental data related to the adsorptions of O-II and CV by chitosan and of CV by mcm-chitosan were applied to McKay et al. equation, and external mass transfer coefficients (k(f)) were also determined. Lastly, chitosan and mcm-chitosan were compared according to their dyestuffs and PNP uptake capabilities. It was seen that mcm-chitosan removed more O-II (99.2%) and RB5 (34.9%) but less CV (3.1%) and PNP (0.9%). (C) 2004 Elsevier B.V. All rights reserved.Öğe Removal of copper, nickel, cobalt and manganese from aqueous solution by kaolinite(Pergamon-Elsevier Science Ltd, 2003) Yavuz, Ö; Altunkaynak, Y; Güzel, FThe removal of some heavy metals such as Mn(II), Co(II), Ni(II), and Cu(II) from aqueous solution is studied using a raw kaolinite. The sorption of these metals on kaolinite conformed to linear form of Langmuir adsorption equation. Langmuir C-m constants for each metal were found as 0.446 mg/g (Mn), 0.919 mg/g (Co), 1.669 mg/g (Ni), 10,787 mg/g (Cu) at 25degreesC, respectively. Also, kinetic and thermodynamic parameters such as enthalpy (DeltaH), free energy (DeltaG) and entropy (DeltaS) were calculated and these values show that adsorption of heavy metal on kaolinite was an endothermic process and the process of adsorption was favoured at high temperatures. (C) 2002 Elsevier Science Ltd. All rights reserved.
