Kinetic and mechanism of thorium(IV) transport through a bulk liquid membrane containing di-2-ethylhexyl phosphoric acid in kerosene

Kinetics and mechanism of thorium (IV) transport through a bulk liquid membrane containing di(-2-ethylhexyl) phosphoric acid in kerosene were investigated. The type and concentration of acid in donor and acceptor phases, initial concentration of thorium in donor phase, carrier concentration, and contact time were studied. The optimum transport of thorium were obtained with 0.0001 M HCl in donor phase, 1.5 M H2SO4 in acceptor phase, 0.2 M D2EHPA in kerosene, 50 mg L-1 of thorium in donor phases, and contact time of order of 960 min. The kinetics of thorium (IV) transport were investigated assuming a consecutive, irreversible extraction and back-extraction reactions. The activation energy values of extraction and back-extraction reactions were calculated to be 29.94 kJ mol-1 and 20.55 kJ mol-1, respectively,which indicates that the extraction process was controlled by the mixed regime (both kinetic and diffusion), and the back-extraction process was mainly controlled by diffusion process.