Extraction kinetics of thorium(IV) and lanthanum(III) nitrates from water-salt solutions of composite materials based on polymer carrier and trialkylamine at different temperatures

One studied the extraction kinetics of thorium [IV] and lanthanum [III] nitrates from the water-salt solutions by a polymer carrier and trialkylamine base composite material under 293.15-333.15 K. One determined the values of the mass transfer coefficients and on the basis of their temperature dependence one evaluated the activation apparent energy. The diffusion through the phase boundary (the film kinetics) is the speed-governing stage of the thorium [IV] and lanthanum nitrate absorption from the water-salt solutions by the composite material. The values of the mass transfer coefficients increase with the increase of the temperature and of the sodium nitrate concentration in the aqueous phase. Ea values do not depend on the sodium nitrate concentration and constitute 5.1±0.3 (Th) and 2.8±0.2 kJxmole-1[La] being typical for the diffusion-controllable processes. To ensure the practical application of the polymer carrier and trialkylamine base composite materials to extract thorium [IV] and lanthanum nitrates the extraction should be performed with the salting-out agents in the aqueous phase under the increased temperatures. It enables to reduce time period to perform the processes and to obtain the maximum values of the equilibrium concentrations of the components at the composition material phase