Process analysis of Rb+ and Cs+ adsorption from salt lake brine by ammonium molybdophosphate composite material

In this paper ammonium molybdophosphate (AMP) and "ammonium molybdophosphate-zirconium phosphate-silica" (AMP-ZrP-SiO2) were prepared as trace Rb+ and Cs+. adsorbents. The two showed good adsorption performance for trace Rb+ and Cs+ when dealing with the salt lake brine. AMP-ZrP-SiO2 has better hydraulics performance, and is more suitable for column adsorption. The adsorption process, enthalpies (Delta H-0), Gibbs free energies (Delta G(0)), and activation energies (E-a) of Rb+ and Cs+ from salt lake brine by the two adsorbents were investigated. The results show that the adsorption processes of Rb+ and Cs+ on AMP and AMP-ZrP-SiO2 are spontaneous and endothermic. The adsorption order of various ions on the two adsorbents is Cs+>Rb+>K+>Mg2+>Na+>Li+ by comparing their Gibbs free energies. Through the analysis of activation energies indicates that AMP-ZrP-SiO2 is more efficient than AMP in the enrichment process of trace Rb+ and Cs+.