Synthesis of MnO_2·0.5H_2O by solid method and its adsorption dynamics for Li~+

The lithium ion-sieve MnO2 ·0.5H2O was prepared by two-step solid phase and its adsorption properties were investigated by XRD and all sorts of relevant dynamic models.The separation characteristics of the lithium ion-sieve for the main metal ions in Salt Lake and circulation adsorption performance were also studied.The results show that the rise of pH is in favour of the adsorption of lithium ion-sieve,but in strong alkali solution the dissolution loss of the lithium ion-sieve also increases accordingly.The adsorption data fit better for the pseudo-second-order rate equation and Langmuir adsorption isotherm equation,and the correlation coefficients reach above 0.998 and 0.993,respectively.The performance of dynamic boundary models is not satisfactory.The lithium ion-sieve has good selectivity for lithium and circulation adsorption performance is very good.This suggests that the adsorption process is chemical adsorption with a single layer and a complicated process with some control steps.