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    Adsorption kinetics of malachite green onto activated carbon prepared from Tuncbilek lignite
    (Elsevier, 2006) Önal, Y; Akmil-Basar, C; Eren, D; Sarici-Özdemir, Ç; Depci, T
    Adsorbent (T(3)K618) has been prepared from Tuncbilek lignite by chemical activation with KOH. Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by t-plot based on N-2 adsorption isotherm. The N-2 adsorption isotherm of malachite green on T(3)K618 is type I. The BET surface area of the adsorbent which was primarily contributed by micropores was determined 1000 m(2)/g. T(3)K618 was used to adsorb malachite green (MG) from an aqueous solution in a batch reactor. The effects of initial dye concentration, agitation time, initial pH and adsorption temperature have been studied. It was also found that the adsorption isotherm followed both Freundlich and Dubinin-Radushkevich models. However, the Freundlich gave a better fit to all adsorption isotherms than the Dubinin-Radushkevich. The kinetics of adsorption of MG has been tested using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. Results show that the adsorption of MG from aqueous solution onto micropores T(3)K618 proceeds according to the pseudo-second-order model. The intraparticle diffusion of MG molecules within the carbon particles was identified to be the rate-limiting step. The adsorption of the MG was endothermic (Delta H degrees = 6.55-62.37 kJ/mol) and was accompanied by an increase in entropy (Delta S degrees = 74-223 J/mol K) and a decrease in mean value of Gibbs energy (Delta G degrees = -6.48 to -10.32 kJ/mol) in the temperature range of 20-50 degrees C. (c) 2005 Elsevier B.V. All rights reserved.
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    Adsorptions of high concentration malachite green by two activated carbons having different porous structures
    (Elsevier, 2005) Akmil-Basar, C; Önal, Y; Kiliçer, T; Eren, D
    The adsorption of malachite green (MG) from aqueous solution by two different adsorbents (CZn5, PETNa8) were studied. Adsorbents were prepared from pine sawdust and polyethyleneterephatalate (PET) by chemical activation with ZnCl2 and NaOH, respectively. The adsorption was carried out in a batch system as a function of dye concentration, pH and contact time. Both adsorbents were found to be very effective in removing the dye at high concentration with adsorption percentage in the order of CZn5 > PETNa8. The pH of dye solution in the range of 6-10, was found favorable for the removal of malachite green by using the two adsorbents at high concentrations. Equilibrium times were 120 and 90 min for CZN5 and PETNa8, respectively. Kinetics of removal MG was studied using Lagergren equation and diffusion phenomena was analyzed using Weber and Morris intraparticle diffusion plots. It was also showed that the adsorption isotherm followed Langmuir model. (c) 2005 Elsevier B.V. All rights reserved.
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    Optimization of nickel adsorption from aqueous solution by using activated carbon prepared from waste apricot by chemical activation
    (Elsevier, 2005) Erdogan, S; Önal, Y; Akmil-Basar, C; Bilmez-Erdemoglu, S; Sarici-Özdemir, Ç; Köseoglu, E; Içduygu, G
    Waste apricot supplied by Malatya apricot plant (Turkey) was activated by using chemical activation method and K2CO3 was chosen for this purpose. Activation temperature was varied over the temperature range of 400-900 degrees C and N-2 atmosphere was used with 10 degrees C/min heat rate. The maximum surface area (1214 m(2)/g) and micropore volume (0.355 cm(3)/g) were obtained at 900 degrees C, but activated carbon was predominantly microporous at 700 degrees C. The resulting activated carbons were used for removal of Ni(H) ions from aqueous solution and adsorption properties have been investigated under various conditions such as pH, activation temperature, adsorbent dosage and nickel concentration. Adsorption parameters were determined by using Langmuir model. Optimal condition was determined as; pH 5, 0.7 g/10 ml adsorbent dosage, 10 mg/l Ni(H) concentration and 60 min contact time. The results indicate that the effective uptake of Ni(II) ions was obtained by activating the carbon at 900 degrees C. (c) 2005 Elsevier B.V. All rights reserved.