الفهرس | Only 14 pages are availabe for public view |
Abstract Cellulose derivatives were synthesized through an intermediary step of chlorination before being functionalized with amino acids moiety (i.e., arginine and glutamic). The sorbents (Arg-Cell and Glu-Cell) have been characterized by elemental analysis, FTIR spectrometry, XRD and SEM-EDX analysis and TGA. In a second step, the sorption properties of these materials were tested for recovery of U(VI) from aqueous solution: pH effect, uptake kinetics and sorption isotherms were investigated. The sorption efficiency increases with pH; this can be attributed to the deprotonation of carboxylic acid and amine groups and to the formation of polynuclear poly-hydrolyzed uranyl species. Sorption isotherms (fitted by the Langmuir equation) show sorption capacities at saturation of the monolayer of 147 and 168 mg U g-1 for Arg-Cell and Glu-Cell, respectively (compared to 78 mg U g-1 for cellulose); maximum sorption capacities at equilibrium (experimental values) reach 138, 160 and 73.4 for Arg-Cell, Glu-Cell and cellulose, respectively. Uranyl sorption is endothermic, spontaneous for amino-acid derivatives of cellulose (contrary to exothermic for cellulose). Uptake kinetics for the different sorbents are fitted by the pseudo-second order rate equation. Uranium can be desorbed using sulfuric acid solutions and the sorbents can be recycled for a minimum of five cycles of sorption/desorption: the decrease in sorption capacities at the fifth cycle does not exceed 13 %. Finally, application of the bench scale results to the extraction of uranium from Gattarian Granite uranium mineralization sample. Uranium desorption efficiency attain 93.2, 92.4 and 87.6 % for maximum sorption capacity of 128 109 and 39 mg/g for Glu-Cell, Arg-Cell and Cell, respectively; which the actual efficiency is found to be 80, 78.09 and 53.42 % following the application on the liquor solution of Gattarian Granite. |