LAUSR

Abstract Elution of sodium persulfate on spinel-type LiMn 2 O 4 were investigated based on the research of hydrolytic process of sodium persulfate solution at different conditions. The hydrolysis of sodium persulfate followed first order kinetics, and the activation energy and pre-exponential factor were 125.41 kJ·mol − 1 and 1.09 × 10 18  h − 1 , respectively. The stoichiometric ratio of S 2 O 8 2 − /H + /SO 4 2 − was 1:2:2. The SO 4 − free radicals were generated during the hydrolysis of sodium persulfate and the hydrolysis rate was determined by the formation rate of SO 4 − . With sodium persulfate solution as eluent, the ratios of both the lithium extraction and manganese loss were low below 35 °C. However, lithium ions were nearly extracted thoroughly with little manganese loss above 75 °C, because the SO 4 − generated in hydrolysis of sodium persulfate had an inhibitory effect on manganese loss. After sodium persulfate solution was hydrolyzed for 72 h at 75 °C, lithium ions were nearly extracted thoroughly, but manganese loss was serious. The products were characterized by scanning electron microscopy (SEM), thermogravimetry (TG), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results showed that the morphology and spinel-type structure were hardly changed after extraction of lithium, and the amount of trivalent manganese decreased with the process of elution. The elution, on the basis of hydrolysis of sodium persulfate, was found a reaction process which involved redox reaction and ion exchange reaction.