The Interfacial Properties Of Cyanex923 And The Solvent Extraction Kinetics Of RE (â…¢)

The materials of rare earth are important function materials. Rare earth elements are important modification agents and adulterate elements, which can improve the properties of traditional materials. The solvent extraction kinetics of La(â…¢), Y(â…¢), Sm(â…¢) and Yb(â…¢) with Cyanex923 in n-heptane from nitrate medium and the interfacial properties of Cyanex923 have been investigated. The goal of this work is to further understand the relationship between the interfacial properties of Cyanex923 and the initial extraction rate, and to offer evidences for extraction mechanism and fundamental information for the applications of solvent extraction of rare earth.1. Using a constant interfacial cell with laminar flow, mass transfer kinetics of La(â…¢), Y(â…¢), Sm(â…¢) and Yb(â…¢) has been studied. The effects of stirring speed, temperature and specific interface on extraction rate have been reviewed. The results show that the values of apparent activation energy (Ea) of purified Cyanex923 extraction are 32.0KJ.mor-1,16.4 KJ.mol-1, 15.1 KJ.mol-1 and 19.2 KJ-mol"1, respectively. Ea of Yb(IQ) with unpurified Cyanex923 extraction is 12.9 KJ.mol-1. The mass transfer of La(m) is controlled by mixed controlled process, the others are controlled by diffusion. The chemical reactions of extraction process occur at the interface.2. The equations of initial extraction rate of La (â…¢), Y (â…¢) and Yb (â…¢) have been obtained. The results show that the extraction mechanism may be changed with the increasing of concentration of Cyanex923. During the process of extraction Yb(â…¢), the impurities of Cyanex923 have better kinetic synergism.3. Using Sigma 701 interfacial tension instrument, the effects of temperature, ion strength, pH value and different thinner on the properties of Cyanex923 have been studied. The interfacial parameters on extractant are obtained.4, According to the interfacial adsorption properties of Cyanex923 and the information of extraction kinetics, the mechanisms of extraction RE(â…¢) have been analyzed.