Speciation modeling and sorption mechanism for decontamination of naturally occurring radionuclide from sulfuric acid liquor by anion exchange process

Various uranyl sulfate complexes are formed during the digestion of monazite mineral by sulfuric acid. Uranyl sulfate sorption by AMBERJET 4200 Cl has been studied to find out the proper mechanism, equilibrium and kinetics basis. At pH of 3.0 and 0.5 M SO₄^- the dominant solution species of U(VI) is [UO₂(SO₄)₃]^-4 anionic complex. High sorbent affinity and monolayer sorption mechanism are approved by different isotherms. The rate is found to be controlled by surface adsorption and intra-particle diffusion. The equilibrium equation and kinetic parameters are estimated. The thermodynamic studies reveal that the reaction is endothermic and spontaneous. (author)