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Molecules 2017, 22(12), 2280;

Adsorption of Cd (II) on Modified Granular Activated Carbons: Isotherm and Column Study

Faculty of Sciences, Department of Chemistry, Research Group on Porous Solids and Calorimetry, Universidad de Los Andes, Carrera 1ra # 18A-12, Bogotá 111711, Colombia
Department of Chemical Engineering, Materials and Industrial Production, Università degli Studi di Napoli Federico II, Piazzale Tecchio 80, 80125 Napoli, Italy
Faculty of Sciences, Department of Chemistry, Universidad Nacional de Colombia, Carrera 30 # 45-03, Bogotá 111321, Colombia
Author to whom correspondence should be addressed.
Received: 15 November 2017 / Revised: 13 December 2017 / Accepted: 14 December 2017 / Published: 20 December 2017
(This article belongs to the Section Green Chemistry)
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In this work, equilibrium and dynamic adsorption tests of cadmium Cd (II) on activated carbons derived from different oxidation treatments (with either HNO3, H2O2, or NaOCl, corresponding to GACoxN, GACoxP, and GACoxCl samples) are presented. The oxidation treatments determined an increase in the surface functional groups (mainly the acidic ones) and a decrease in the pHPZC (except for the GACoxCl sample). A slight alteration of the textural parameters was also observed, which was more significant for the GACoxCl sample, in terms of a decrease of both Brunauer-Emmett-Teller (BET) surface area and micropore volume. Adsorption isotherms were determined for all the adsorbents and a significant increase in the adsorption performances of the oxidized samples with respect to the parent material was observed. The performances ranking was GACoxCl > GACoxP > GACoxN > GAC, likely due to the chemical surface properties of the adsorbents. Dynamic tests in a fixed bed column were carried out in terms of breakthrough curves at constant Cd inlet concentration and flow rate. GACoxCl and GACoxN showed a significantly higher value of the breakpoint time, likely due to the higher adsorption capacity. Finally, the dynamic tests were analyzed in light of a kinetic model. In the adopted experimental conditions, the results showed that mass transfer is controlled by internal pore diffusion, in which surface diffusion plays a major role. View Full-Text
Keywords: modified activated carbon; adsorption; cadmium; fixed bed column; oxidation treatment; kinetic model modified activated carbon; adsorption; cadmium; fixed bed column; oxidation treatment; kinetic model

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Rodríguez-Estupiñán, P.; Erto, A.; Giraldo, L.; Moreno-Piraján, J.C. Adsorption of Cd (II) on Modified Granular Activated Carbons: Isotherm and Column Study. Molecules 2017, 22, 2280.

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