Solid-liquid extraction behavior of trivalent rare earths by tributyl phosphate at high temperatures

Solid–liquid extraction behaviors of trivalent rare earths (La–Lu, Y) from ammonium thiocyanate solution by tributyl phosphate using molten paraffin wax as diluent were studied and optimum extraction conditions were determined. In 10 mL of aqueous RE³⁺ solution where C_RE(III) = 4.0 × 10⁻³ mol·L⁻¹, when additions of tributyl phosphate and ammonium thiocyanate are 5.00 mL and 2.80 g, respectively, extraction distribution ratios are over 10. The procedure can be used for rapid extraction separation of rare earths. An extraction mechanism was also investigated, and the complex species extracted into organic phase is RE(TBP)(SCN)(NO₃)₂. © 1999 John Wiley & Sons, Inc. Lab Robotics and Automation 11: 229–233, 1999