Multifunctional hierarchical cabbage-like nZVI-Fe3O4/C composites for efficient chromium (VI) removal

There is an interesting yet challenging task to develop a facile procedure for designing multifunctional carbonaceous materials for environmental applications. In this research, multifunctional hierarchical cabbage-like carbonaceous materials (Fe/CCMs-X) have been fabricated via a facile hydrothermal carbonization (HTC) of furfural in the presence of cobalt acetylacetonate, followed by simple impregnation iron salts and heating treatment. The structure, morphology and magnetic properties were characterized by powder X-ray diffraction (XRD), N 2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM) techniques; and its adsorption behaviors of Cr(VI) were investigated in detail. Batch experiments were conducted at relatively mild conditions (pH ∼ 3). The adsorption equilibrium data was best fitted by Langmuir isotherm model and the adsorption kinetics followed pseudo-second-order models. The maximum capacity predicted by the Langmuir model is 75.3   mg/g for Fe/CCMs-800. Furthermore, thermodynamic parameters (Δ H >   0, Δ S >   0, and Δ G <   0) revealed that the sorption reaction was a spontaneous and endothermic process. Most of important, the excellent magnetism (79.9   emu   g −1 ) provided an ideal magnetic-separation performance from aqueous systems. It demonstrated that this newly prepared multifunctional hierarchical carbonaceous materials (Fe/CCMs-X) are promising sorbents for chromium(VI) ions removal from water.