Towards magnetic responsive chalcogenides for efficient separation in water treatment: facile synthesis of magnetically layered chalcogenide Fe3O4/KMS-1 composite adsorbents and their zinc removal application in water

Abstract

A facile strategy was designed to prepare magnetically layered chalcogenide Fe₃O₄/KMS-1 (FK) composite adsorbents combining the advantages of rapid magnetic separation and satisfactory adsorption performance under vigorous stirring in ethanol solution at room temperature. The dispersion degree of Fe₃O₄ in ethanol was superior to that in water, which gave a better result with the preparation in ethanol. Characterization by SEM-EDS, XRD, magnetic test, N₂ physical-adsorption and TG-DTG demonstrated formation of FK and its adsorption performance. The results showed that the Fe₃O₄ microspheres could be well distributed over the surface of KMS-1 by electrostatic attraction in ethanol and the obtained FK could be easily separated from water after adsorption using a magnet. The pH slightly affected the adsorption capacity in the range of 3 to 6. Both KMS-1 and Fe₃O₄ retained their own original adsorption capacity in FK and FK_0.3 was the best composite adsorbent when the mass ratio of Fe₃O₄ and KMS-1 was 0.3. As the amount of loaded Fe₃O₄ was decreased, the adsorption capacity of the composite adsorbents increased. The kinetic data of FK_0.3 fit well with pseudo-second-order models. The co-existing ions had a slight effect on the removal of Zn(II) by FK_0.3. The interlayer spacing of KMS-1 in FK increased from 0.851 nm to 1.123 nm after adsorption. The FK composite adsorbents can be considered as an excellent recoverable adsorbent in the treatment of wastewater.