Adsorption behaviors of tetracycline on magnetic graphene oxide sponge

•Magnetic graphene sponge (MGOS) was prepared for antibiotics tetracycline adsorption.•MGOS had huge capacity for tetracycline (473 mg/g), 50% higher than that of graphene oxide.•The adsorption process was moderately fast and could be described by pseudo-second-order model.•The small size and negative charge of Fe3O4 contributed to the improved performance of MGOS.

Magnetic nanoparticles were adopted for the synthesis of magnetic graphene adsorbents, but the incorporation of magnetic nanoparticles significantly reduced the adsorption capacity of graphene for antibiotics. In this study, we prepared magnetic graphene oxide sponge (MGOS) by lyophilizing the dispersion of Fe3O4 nanoparticles and graphene oxide (GO) for tetracycline adsorption. GO self-assembled to form large sheets that built the large pores in MGOS. Fe3O4 nanoparticles were attached on GO sheets, enabling the magnetic property of MGOS. The adsorption capacity of MGOS for tetracycline was 473 mg/g, showing 50% increase comparing to GO. The adsorption was moderately fast and could be described by pseudo-second-order model. The thermodynamics investigation indicated that the adsorption was endothermic and the driving force was entropy increase. The pH had mild influence on the adsorption, while ionic strength nearly had no impact. The implication to the applications of MGOS in antibiotics remediation is discussed.

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