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    Application of fly ash and activated carbon in the removal of Cu(2+) and Ni(2+) ions from aqueous solutions
    (TAYLOR & FRANCIS INC, 2008) Pehlivan, E.; Cetin, S.
    The main objective of this study was to remove Cu(2+) and Ni(2+) ions from aqueous solution by using fly ash, an industrial solid waste of the sugar industry and commercial activated carbon at equilibrium, which follows Langmuir and Freundlich adsorption isotherms. In order to identify influential parameters and to evaluate their interactions, effects of time, pH, initial metal concentration, and amount of adsorbent were studied, and the results were compared with those of activated carbon under the same experimental conditions. Adsorption studies were performed in a time interval (1-240 min), at various pH values (2.0-8.0) at 25 degrees C and at metal concentrations of 1-10 x 1(-4) M using different amounts of adsorbent (1-12 g/L). The equilibrium time was fixed at 60 min in the case of Cu(2+) and Ni(2+), and 8 g/L of fly ash and 6 g/L activated carbon was sufficient for the optimum removal of both the metal ions. The sorption of metal ions increased with an increase of pH, and maximum removal was obtained at 5.0 for fly ash with 97.2% and 78.2% removal for Cu(2+) and Ni(2+) ions, respectively. For AC, on the other hand, maximum removal was obtained at 4.0 for Cu(2+) and 6.0 for Ni(2+) with 95.0% and 63.0% removal, respectively. The adsorption capacities are 7.0 mg/g for Cu(2+), 5.9 mg/g for Ni(2+) for fly ash, and 6.9 mg/g for Cu(2+), 5.4 mg/g for Ni(2+) for activated carbon. The orders of adsorption of heavy metal ions for fly ash and activated carbon change in the order of Cu(2+) Ni(2+) and Cu(2+) Ni(2+), respectively. The fly ash was found to be a metal adsorbent as effective as commercial activated carbon.
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    Removal of Cu(II) and Ni(II) from aqueous solution by lignite-based humic acids
    (TAYLOR & FRANCIS INC, 2007) Arslan, G.; Cetin, S.; Pehlivan, E.
    The removals of Cu(II) and Ni(II) metal ions from an aqueous solution were investigated by using humic acids (HAs) in a batch arrangement. HAs were prepared by using alkaline extraction, following sedimentation and acidic precipitation from three Turkish lignites: Ilgin, Beysehir, and Ermenek. The interactions of Cu(II) and Ni(II) with solid HAs and influence of three parameters (initial metal concentration, solution pH and temperature) on the removal of metals were studied. Adsorption equilibrium was achieved in about 120 min for Cu(II) and Ni(II) ions. The sorption of Cu( II) and Ni(II) on the surface of HAs depended strongly on the pH, and increased with increasing of pH and the initial concentration of metal. The sorption of Cu(II) was higher than that of Ni(II) for HAs. The equilibrium relationship between adsorbent and adsorbate is described by adsorption isotherms at a fixed temperature 35 degrees C, at pH similar to 4.0. The Langmuir adsorption isotherm was used to describe observed sorption phenomena. It was observed that the maximum adsorption capacity of Cu(II)/g was 0.27 mmol for Ilgin (HA(1)) and Beysehir (HA(2)), 0.19 mmol for Ermenek (HA(3)) and that of Ni(II)/g was 0.28 mmol for HA(1), 0.24 mmol for HA(2), 0.18 mmol for HA(3) at pH 4.1, respectively. More than 80% of Cu(II) was removed by HA(1) and HA(2) and 58% by HA(3), 82% of Ni( II) was removed by HA(1), 71% by HA(2) and 52% by HA(3) from aqueous solution. The adsorption of Cu( II) and Ni( II) was higher between pH 4.1 and 5.1 for all HAs, and maximum sorption was observed at pH 4.1. The increase in temperature caused a slight decrease in the value of the equilibrium constant (Kc) for the sorption of metal ions. Adsorption isotherms and kinetics data of Cu( II) and Ni( II) ions removed by HAs are presented and discussed.
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    Sorption of Cr(VI) ions on two Lewatit-anion exchange resins and their quantitative determination using UV-visible spectrophotometer
    (ELSEVIER SCIENCE BV, 2009) Pehlivan, E.; Cetin, S.
    The sorption of Cr(VI) from aqueous solutions with macroporous resins which contain quarternary amine groups (Lewatit MP 64 and Lewatit MP 500) was studied at varying Cr(VI) concentration, adsorbent dose. pH, contact time and temperature. Batch shaking sorption experiments were carried out to evaluate the performance of Lewatit MP 64 and Lewatit MP 500 anion exchange resins in the removal of Cr(VI) from aqueous solutions. The concentration of Cr(VI) in aqueous solution was determined by UV-visible spectrophotometer. The ion exchange process, which is dependent on pH, showed maximum removal of Cr(VI) in the pH range 3-7 for an initial Cr(VI) concentration of 1 x 10(-3) M. The optimum pH for Cr(VI) adsorption was found as 5.0 for Lewatit MP 64 and 6.0 for Lewatit MP 500. The maximum Cr(VI) adsorption at pH 5.0 is 0.40 and 0.41 mmol/g resin for Lewatit MP 64 and Lewatit MP 500 anion exchangers, respectively. The maximum chromium sorption occurred at approximately 60 min for Lewatit MP 64 and 75 min for Lewatit MP 500. The suitability of the Freundlich and Langmuir adsorption models was also investigated for each chromium-sorbent system. The uptake of Cr(VI) by the anion exchange resins was reversible and so it has good potential for the removal of Cr(VI) from aqueous solutions. Both ion exchangers had high bonding constants but Lewatit MP 500 showed stronger binding. The rise in the temperature caused a slight decrease in the value of the equilibrium constant (K(c)) for the sorption of Cr(VI) ion. (c) 2008 Elsevier B.V. All rights reserved.