Construction of MnO2@ZIF-8 core-shell nanocomposites for efficient removal of Sr2+ from aqueous solution

Novel MnO2@ZIF-8 nanocomposites were synthesized for efficient adsorptive removal of Sr2+ from aqueous solution. ZIF-8 nanoparticles with controlled morphology and size were first synthesized by using amino acids to modulate the crystal nucleation and growth. Then, a layer of MnO2 nanoparticles were deposited on ZIF-8 surface by using the adsorbed amino acid molecules as binding sites to mediate MnO2 mineralization and by adjusting the reactive KMnO4 concentration to control the size and surface density of the MnO2 nanoparticles. The as-prepared MnO2@ZIF-8 nanocomposites showed a core-shell structure and displayed superior performance in Sr2+ adsorption and removal from aqueous solution. The adsorption process can be described well by the pseudo-second-order equation. The adsorption isotherm accords well with the Langmuir model and the maximum adsorption capacity can reach 65.7 mg/g. The study paves a new way to develop novel inorganic nanocomposites as highly efficient and potential adsorbents for the treatment of radionuclide-containing wastewater.