Preconcentration of U(VI) from aqueous solutions after sorption using Sorel’s cement in dynamic mode

Summary

Mg(OH)₂ was identified as a component of Sorel’s cement being a very strong sorbent for uranium. Sorel’s cement is a mixture of MgO, MgCl₂ and water. The optimal conditions for the adsorption of U(VI) was studied by the batch method. A contact time of 2 hours was found to be optimum. Maximum U(VI) uptake was observed in a pH range of 5.5-6.5 with a sorption constant of K_ads = 0.9 h^-1 at initial concentration of 20 ppm. Polypropylene columns filled with 2 g of Sorel’s cement at a mesh size of 35 were used for the preconcentration of uranium by passing 8 l of water containing 10 ppb U(VI). A flow rate of 0.25 ml/min and a bed height of 5 cm were found to be the optimum for the U(VI) separation. A 5 wt% triphenylphosphine oxide solution in toluene was used as an organic solvent for the separation of uranium from interfering elements such as iron(III) and thorium(IV), prior to spectrophotometric analysis. The determination of U(VI) was accomplished by adding Arsenazo III as a coloring reagent to the solution and using a UV-160A spectrophotometer.