Kinetics of extraction and back extraction of Pr(III) and Nd(III) nitrates from aqueous electrolyte solutions with a composite material based on polymer-supported tri-n-butyl phosphate at various temperatures

Abstract

Kinetics of extraction and back extraction of Pr(III) and Nd(III) nitrates from aqueous electrolyte solutions with a composite material (CM) based on polymer-supported tri-n-butyl phosphate (TBP) at 293.15–333.15 K is studied. The rate-determining stage of the processes is found to be the interfacial diffusion (film kinetics). The mass-transfer coefficients are determined, and, from their temperature dependences, the apparent activation energy E a is estimated. In extraction, the mass-transfer coefficients increase in passing from aqueous solutions of Pr(III) and Nd(III) nitrates to those containing 2 M NaNO3 and with increasing temperature. For the extraction, E a is found to be 25±1 kJ mol−1, and for back extraction, 15.5±1.0 kJ mol−1. The E a values are independent of particular Ln(III).