Selective adsorption of uranium from aqueous solutions using activated carbon prepared from charcoal by chemical activation

Activated carbon was prepared from charcoal by chemical activation in this study. The preparation process consisted of zinc chloride impregnation followed by carbonization. The carbonization temperature ranges from 500 to 700 °C for 1 h. Activated carbon produced from charcoal has been shown to be a good adsorbent for uranium from liquid aqueous radioactive wastes. The adsorption of uranium was studied as a function of pH, concentration of adsorbate, shaking time, particle size, amount of adsorbent and temperature. ?H° and ?S° were calculated from the slope and intercept of plots of In K D versus 1/T. The uranium adsorption efficiency was found as 92 ± 4%. The influence of different cations on uranium adsorption has been examined. © 2004 Elsevier B.V. All rights reserved

Can Carbon Nanotubes Play a Role in the Field of Nuclear Waste Management?

Carbon nanotubes (CNTs) are a novel and interesting graphitic carbon material which, since its discovery (1, 2), has attracted considerable attention due to its unique structuralandphysicochemical properties.CNTsare basically carbon macromolecules in the shape of a hollow cylinder, usually capped at least at one end, and characterized by a length-to-diameter ratio e106 (Figure 1); the diameter of a nanotube ranges from a few to tens of nanometers, while its length can reach up to several millimeters. According to their structure, CNTs are categorized as single-walled (SW) or multiwalled (MW), see Figure 1a and c, respectively. Each wall consists of a flat molecular network of C atoms known as graphene (graphite is the material composed of overlaying graphene sheets), while CNT end caps include pentagonal rings to fit the geodesic curvature. The interwall distance in MWNTs is on the order of a few angstroms.JRC.E.5-Nuclear chemistr

Biosorption of Ce(III) onto modified Pinus brutia leaf powder using central composite design

The biosorption of Ce(III) from aqueous solution by citric acid-modified Pinus brutia leaf powder was studied in a batch system as a function of initial pH, temperature, initial concentration of adsorbate, and contact time. Central composite design method was used in the experiments. Thermodynamic parameters such as standard enthalpy (?H 0), entropy (?S 0), and free energy (?G 0) were calculated, and the results indicated that biosorption was exothermic. The biosorption of Ce(III) on modified Pinus brutia leaf powder was investigated by Freundlich, Langmuir, and Dubinin-Radushkevich (D-R) isotherms. The results show that Ce(III) adsorption can be explained by Langmuir isotherm model, and monolayer capacity was found as 62.1 mg/g. The results suggested that the modification process enhances the biosorption capacity of the adsorbent, and modified Pinus brutia leaf powder may find promising applications for the recovery of Ce(III) from aqueous effluents. © Springer-Verlag 2011