Microwave hydrothermal fabrication of CuFeCr ternary layered double hydroxides with excellent Cr(VI) adsorption

CuFeCr ternary-layered double hydroxides (L-CuFeCr) were prepared via the microwave hydrothermal method and used as an adsorbent for removing hexavalent chromium (Cr(VI)) ions in aqueous solution. Powder X-ray diffraction confirmed the formation of well crystalline L-CuFeCr. Scanning electron microscopy and transmission electron microscopy showed that the spherical structure of L-CuFeCr was formed by the stacking of nanosheets. When the molar ratio of Cu/Fe/Cr was 6:2:1, the as-obtained L-CuFeCr possessed a larger specific surface area (100.3 m²/g) and exhibited a high adsorption performance. The saturated adsorption capacity reached 22.24 mg/g for Cr(VI) ions at pH= 2. The adsorption process of this new adsorbent fitted well with the pseudo-second-order kinetic model and the adsorption isotherm followed Langmuir adsorption isotherm, indicating a monolayer and chemical adsorption. This study demonstrates that L-CuFeCr can be used as an excellent adsorbent to remove Cr(VI) ions from aquatic environments.