Fabrication and performance of the ammonium molybdophosphate/polysulfone mixed matrix membranes for rubidium adsorption in aqueous solution

The separation of the rare and precious metal rubidium is still a challenge to hydrometallurgy and material science. A novel ammonium molybdophosphate (AMP)/polysulfone (PSf) mixed matrix membrane for rubidium adsorption and separation was prepared successfully by NIPs method via immobilizing AMP into the PSf porous membrane. FTIR, XRD, SEM tests indicate that AMP is embedded into the PSf matrix, and its crystalline structure remains intact. WCA tests show that the membrane surfaces are more and more hydrophilicity with the AMP blending content increasing. The fluxes increase approximately linearly from 210.2 to 370.2 L m(-2) h(-1) with the AMP content while the bovine serum albu rejections decrease from 97.8% to 88.5%. The Rb+ adsorption capacities of the membranes studied as a function of contact time, pH, Rb+ concentration, temperature, presence of various interference ions, and the Rb+ capacity is up to 98.4 mg g(-1) at the optimal adsorption conditions. The Rb+ adsorption on the AMP/PSf porous membrane complies with Langmuir adsorption isotherms and pseudo-second-order kinetic model. Finally, the reusability in Rb+ adsorption of the AMP/PSf porous membrane is investigated, and the recovery rate can still be maintained above 95% after five adsorption-desorption recycles.