Preparation, characterization and enhanced adsorption performance for Cr(VI) of mesoporous NiFe2O4 by twice pore-forming method

Magnetic mesoporous NiFe2O4 with higher surface area has been prepared by the twice pore-forming method, including the calcination of the oxalate precursor and leaching of ZnO pore-forming agent. The X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and BET surface area measurement are used to evaluate the pore structural parameters and surface chemistry of the adsorbent respectively. The pore-forming mechanism is proposed based on the experimental results. The adsorption behavior of mesoporous NiFe2O4 for Cr(VI) is investigated in detail. The results show that kinetic data follow a pseudo-second-order model and equilibrium data are well fitted by the Langmuir model. The maximum adsorption capacity is 43.68 mg g−1 at pH 2. The removal for Cr(VI) is mainly physisorption process derived from coulombic interaction. The as-prepared TPF-NiFe2O4 is promising as sorbent for Cr(VI) removal because of its higher adsorption capacity, separation convenience and highly efficient reusability.