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Öğe 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.Öğe Removal of metal ions using lignite in aqueous solution - Low cost biosorbents(ELSEVIER SCIENCE BV, 2007) Pehlivan, E.; Arslan, G.Turkish lignite can be used as a new adsorption material for removing some toxic metals from aqueous solution. The adsorption of lignite (brown young coals) to remove copper (Cu2+), lead (Pb2+), and nickel (Ni2+) from aqueous solutions was studied as a function of pH, contact time, metal concentration and temperature. Adsorption equilibrium was achieved between 40 and 70 min for all studied cations except Pb2+, which is between 10 and 30 min. The adsorption capacities are 17.8 mg/g for Cu2+, 56.7 mg/g for Pb2+, 13.0 mg/g for Ni2+ for BC1 (Ilgin lignite) and 18.9 mg/g for Cu2+, 68.5 mg/g for Pb2+, 12.0 mg/g for Ni2+ for BC2 (Beysehir lignite) and 7.2 mg/g for Cu2+, 62.3 mg/g for Pb2+, 5.4 mg/g for Ni2+ for AC (activated carbon). More than 67% of studied cations were removed by BC1 and 60% BC2, respectively from aqueous solution in single step. Whereas about 30% of studied cations except Pb2+, which is 90%, were removed by activated carbon. Effective removal of metal ions was demonstrated at pH values of 3.8-5.5. The adsorption isotherms were measured at 20 degrees C, using adsorptive solutions at the optimum pH value to determine the adsorption capacity The Langmuir adsorption isotherm was used to describe observed sorption phenomena. The rise in temperature caused a slight decrease in the value of the equilibrium constant (K-c) for the sorption of metal ions. The mechanism for cations removal by the lignite includes ion exchange, complexation and sorption. The process is very efficient especially in the case of low concentrations of pollutants in aqueous solution, where common methods are either economically unfavorable or technically complicated. (C) 2006 Elsevier B.V. All rights reserved.Öğe Uptake of Cr3+ from aqueous solution by lignite-based humic acids(ELSEVIER SCI LTD, 2008) Arslan, G.; Pehlivan, E.Humic acid (HA) produced from brown coal, a relatively abundant and inexpensive material is currently being investigated as all adsorbent to remove toxic metals from aqueous solution. The influence of five parameters (contact time, solution pH, initial metal concentration, temperature and amount of adsorbent) on the removal at 20 +/- 1 degrees C was studied. HAs were prepared from lignites by using alkaline extraction, sedimentation and acidic precipitation. Adsorption equilibrium was achieved in about 60 min for Cr3+ ion. The Langmuir adsorption isotherm was used to describe observed sorption phenomena. The maximum adsorption capacity of 0.17 mmol for Ilgin (HA(1)), 0.29 mmol for Beysehir (HA(2)) and 0.18 mmol Ermenck (HA(3)) and 0.17 mmol of Cr3+/g for activated carbon (AC) was achieved, respectively at pH of 4.1. More than 84% of Cr3+ was removed by HA(2), 54% by HA(3) and 51% by HA(1) and 50% by AC from aqueous solution. The adsorption was strongly dependent on pH but independent of ionic strength and metal ions. The adsorption of Cr3+ was higher between pH 4.1 and 5.1 for all HAs and maximum sorption was observed at pH 4.1. The rise in temperature caused a slight decrease in the value of the equilibrium constant (K-c) for the sorption of Cr3+ ion. Complex mechanisms including ion exchange, complexation and adsorption and size exclusion are possible for sorption of Cr3+ ion on HAs. (C) 2008 Elsevier Ltd. All rights reserved.Öğe Uptake of metal ions on humic acids(TAYLOR & FRANCIS INC, 2006) Pehlivan, E.; Arslan, G.The kinetics, the sorption capacities, pH and temperature dependence of sorption of humic acids (HAs) of Turkish brown coals with respect to Zn(II), Cu(II), Ni(II), Co(II) and Pb(II) ions were investigated, and the roles of the carboxylic and phenolic groups in the adsorption of metals ion on HAs were searched in this work. These metal ions are able to form complex compounds with carboxylic and phenolic groups of HAs. Adsorption equilibrium was achieved in between 50 and 60 min for all studied cations. HAs extracted from different brown coals have been characterized by chemical and physical methods. The chemical properties of HAs showed differences depending on the source from which they were obtained. The sorption of metals on the surface of HAs depends strongly on the pH, and sorption decreases with decreasing pH. Maximum removal of metal ions was demonstrated at pH values of 4.1-5.0. The Langmuir adsorption isotherm was used to describe observed sorption phenomena. The Delta G(0) became negative as the temperature increased, and so the equilibrium constant decreased slightly. The investigation proved that the HAs are suitable materials for the studied heavy metal ion removal from aqueous solution and could be considered as potential material for purification of effluent polluted with toxic metal ions.
