title: Solvent extraction kinetics of rare earth elements.
abstract: The kinetics of solid-liquid extraction of rare earth elements (RE) (La, Ce, Sm, Dy and Yb) were studied with 1-(2-pyridylazo)-2-naphthol (PAN) at 60 degrees C using paraffin wax as a diluent. The rate of extraction is first order with respect to metal ion and hydrogen ion in the aqueous phase and second order with respect to the extractant in the organic phase. The rate-determining step is the formation of an [RE(PAN)(2)](+) complex between RE(3+) and PAN in the aqueous phase. The rate constant for the extraction was found to be about 10(11) 1 mol(-1) s(-1). The temperature dependence of extraction rate was determined and the activation parameters were calculated.
authors.affiliation: Department of Chemistry, Northwest Normal University, Lanzhou, People's Republic of China.
authors.forename: J
authors.initials: J
authors.lastname: Gao
authors.forename: B
authors.initials: B
authors.lastname: Peng
authors.forename: H
authors.initials: H
authors.lastname: Fan
authors.forename: J
authors.initials: J
authors.lastname: Kang