Magnetic zeolite imidazole framework material-8 as an effective and recyclable adsorbent for removal of ceftazidime...

Zeolitic imidazolate framework-8 (ZIF-8) was synthesized by solvothermal method and the adsorption pore size was adjusted by changing the amount of template agent. The ZIF-8@SiO₂@Fe₃O₄ derived from self-assembly of ZIF-8 and SiO₂@Fe₃O₄ were then synthesized and used for ceftazidime (CAZ) removal. ZIF-8 was a regular dodecahedral particle with uniform particle size. The pore diameter was 6.47 nm and the specific surface area was 1182.5 m²·g^-1 in ZIF-8@SiO₂@Fe₃O₄. The adsorption of CAZ on ZIF-8@SiO₂@Fe₃O₄ as a function of adsorption temperature, contact time, ionic strength solution pH, and humic acid concentration were investigated. The error of equilibrium adsorption capacity between model fitting and actual experiments is only 1.19%. Kinetics for CAZ removal on ZIF-8@SiO₂@Fe₃O₄ was found to follow pseudo-second-order kinetics. Langmuir, Freundlich and Sips isotherm fitted the adsorption data well and gave similar correlation coefficients, suggesting a single layer adsorption of CAZ on ZIF-8@SiO₂@Fe₃O₄. The ZIF-8@SiO₂@Fe₃O₄ showed no apparent loss in CAZ adsorption after five cycles. These features indicate that the ZIF-8@SiO₂@Fe₃O₄ may be a promising adsorbent for CAZ removal from aqueous solution.