Preparation of ZIF-8-Based Functionalized Magnetic Nanocomposites and Their Application in Aqueous Environment

In this study, a functionalized magnetic powder complex porous carbon derived from ZIF-8 (ZIF-8@Na-Cit@Fe₃O₄NPs@AC(500°C)) was prepared and applied for the waste liquid containing MB, TC, and Cu²⁺ adsorption removal. The ZIF-8@Na-Cit@Fe₃O₄NPs@AC(500°C) perfectly inherited the feature of parent ZIF-8, posed a high specific surface area (SBET = 812.73 m² g⁻¹), be rich in surface nitrogen functional groups, and resulting in a good dynamic adsorption of the MB, TC, and Cu²⁺. The ZIF-8@Na-Cit@Fe₃O₄NPs@AC(500°C) exhibited the best adsorption performance of high-concentration waste liquid containing MB, TC, and Cu²⁺, with equilibrium adsorption capacity of MB (408 mg g⁻¹), TC (417 mg g⁻¹), and Cu²⁺ (386 mg g⁻¹), respectively. The acetone and toluene adsorption were spontaneously and exothermic, given the negative values of free energy (ΔG) and enthalpy (ΔH). The difference of MB, TC, and Cu²⁺ adsorption on ZIF-8@Na-Cit@Fe₃O₄NPs@AC(500°C) attributed to the affinity difference (polarity and molecular diameter) and the nitrogen-containing functional groups (π-π interaction and electrostatic attraction). Therefore, it was found that ZIF-8@Na-Cit@Fe₃O₄NPs@AC(500°C) could effectively adsorb MB, TC, and Cu²⁺, and ZIF-8@Na-Cit@Fe₃O₄NPs@AC(500°C) could remove more than 70% of the above pollutants after repeated use for four times; it has a good application prospect.