Extraction of uranium by amine, amide and benzamide grafted covalently on silica gel

Organic complexing moieties such as amine, 2degrees-amide and benzamide functional groups were covalently linked to silica gel by performing organomodification on commercially available silica gel. The extraction of uranium as a function of pit, time, concentration of uranium and the effect of ions such as Fe2+, CO2+, Ni2+ and CO32- on the distribution coefficient of uranium by sorbent was studied. The data was fitted into Langmuir adsorption isotherm. The selectivity of the sorbents towards uranium were found to decrease in the order gel-amine >> gel-benzamide congruent to gel-2degrees-amide at all pHs. The presence of metal ions such as Fe2+, CO2+, Ni2+ and CO32- were found to decrease the distribution coefficients (K-d, ml/g) of uranium and the decrease was very high when Fe2+ was present. The performance of the sorbent, gel-amine, under a given column condition was tested by following the breakthrough curve of uranium up to C/C-0 = 0.025. The sorbent was found to be good for the quantitative pre-concentration of uranium from a large amount of sodium.