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

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 m(2).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.