title: Removal of chromium(VI) from aqueous solution by activated carbons: kinetic and equilibrium studies.
abstract: The objective of this study is to assess the uptake of hexavalent chromium (Cr(VI)) from aqueous solutions onto activated carbons (AC) produced from wood. Two activated carbons are tested, a KOH-activated carbon and a commercial H3PO4-activated carbon (Acticarbone CXV). The adsorption of Cr(VI) is maximal at the lowest values of pH (pH 3) and increases with temperature for both adsorbents. The KOH-activated carbon shows higher capacity for adsorption of Cr(VI) than Acticarbone. The sorption isotherms fit the Langmuir model accurately. The adsorption reaction was found to obey a pseudo second-order rate. The activation energy and the pre-exponential factor as well as the thermodynamic functions related to adsorption reaction, DeltaS degrees , DeltaH degrees , DeltaG degrees , were determined. Nevertheless, the global reaction rate is probably controlled by the intra-particular diffusion of Cr(VI) and the mass diffusivity of Cr(VI) was evaluated.
authors.affiliation: Université de Technologie de Compiègne, Département de Génie Chimique, Laboratoire de Génie des Procédés Industriels, UMR 6067 du CNRS-BP 20529, 60205 Compiègne, France.
authors.forename: Lotfi
authors.initials: L
authors.lastname: Khezami
authors.forename: Richard
authors.initials: R
authors.lastname: Capart
mesh_terms: D000327:Adsorption; D002606:Charcoal / Q000737:chemistry*; D002857:Chromium / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000517:prevention & control; D007700:Kinetics; D009584:Nitrogen / Q000737:chemistry; D009994:Osmolar Concentration; D012996:Solutions; D013696:Temperature; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification; D014877:Water Pollution, Chemical / Q000517:prevention & control
chemical_list: D007220:Industrial Waste; D012996:Solutions; D014874:Water Pollutants, Chemical; D014867:Water; D002857:Chromium; D002606:Charcoal; C074702:chromium hexavalent ion; D009584:Nitrogen