Enhanced adsorption efficiency of inorganic chromium (VI) ions by using carbon-encapsulated hematite nanocubes

Abstract In this study, carbon-encapsulated hematite nanocubes with an edge length of ~20 nm (α-Fe2O3@C) were prepared by a two-step hydrothermal method using glucose as a carbon source. The α-Fe2O3@C nanocomposite was found to exhibit enhanced adsorption efficiency for inorganic chromium (VI) ions as compared to bare α-Fe2O3 nanocubes. At optimized conditions, the maximum adsorption capacity and removal efficiency of Cr(VI) using α-Fe2O3@C nanocomposites were 76.92 mg g−1 and 97.6%. The influence of carbon content on the structural features, and on the mechanism of adsorption of the α-Fe2O3@C nanocomposites were investigated and discussed. Adsorption data revealed that the adsorption behavior of the α-Fe2O3@C nanocomposites for chromium (VI) showed good agreement with both Langmuir and pseudo-second-order kinetic models. Moreover, the α-Fe2O3@C nanocomposites still retain high chromium (VI) removal efficiency after three recycles. Carbon-encapsulated hematite nanocubes with high Cr(VI) removal efficiency and excellent regenerability will become a promising absorbent toward the treatment of heavy metals from water solution.