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.