Abstract
Magnetic sepiolite was synthesized by chemical precipitation of Fe3+ and Fe2+ at sepiolite suspension. Removal kinetics of U(VI) on sepiolite and magnetic sepiolite can be well fitted by pseudo-second-order and pseudo-first-order kinetic models, respectively. At pH < 5.0, U(VI) removal on sepiolite significantly decreased with increasing ionic strength, whereas U(VI) removal on magnetic sepiolite was independent of ionic strength. The maximum removal capacity of sepiolite and magnetic sepiolite at pH 5.0 and 298 K calculated from Langmuir model were 28.17 and 74.63 mg/g, respectively. XANES spectra suggested that U(VI) was partly reduced to U(IV) at long-term conditions.