Preparation of a core-shell magnetic potassium nickel copper hexacyanoferrate/zeolitic imidazolate framework composite for rubidium adsorption

Magnetic substrates are favorable for separating adsorption-saturated powder adsorbents from solutions. Here, a core-shell magnetic potassium nickel copper hexacyanoferrate composite (MKNiCuFC@ZIF-8) modified with zeolitic imidazolate frameworks was synthesized for selective extraction of rubidium (Rb) in solution. MKNiCuFC@ZIF-8 was analyzed in depth using N2 adsorption-desorption, SEM, XRD, FT-IR, XPS, etc. Batch experiments were employed to assess the adsorption properties of MKNiCuFC@ZIF-8 for Rb+. The adsorption behavior based on the exchange behaviors of Rb+ and K+ conforms to the pseudo-second-order kinetic model. Meanwhile, the adsorption data are well fitted through the Langmuir isotherm model and reached a maximum adsorption amount of 1030.69 mg g−1 at 45 °C. Furthermore, MKNiCuFC@ZIF-8 could be regenerated with 90.3 % of absorbed Rb+ being desorbed in 1 mol L−1 of KCl within 24 h. The graphical abstract represents the synthesis procedure of the MKNiCuFC@ZIF-8 composite adsorbent. Potassium nickel copper hexacyanoferrate was generated on the surface of Fe3O4 coated with PDA using an in-situ approach and modified with ZIF-8, forming a magnetic composite (MKNiCuFC@ZIF-8). [Display omitted] •The Rb+ uptake onto MKNiCuFC is enhanced due to the ZIFs-grafted.•MKNiCuFC@ZIF-8 can be recovered from the solution using magnetic force.•Selectivity for Rb+ in the presence of interfering ions was confirmed.•The magnetic adsorbent can be validly regenerated using KCl.