Enhanced chitosan/Fe0-nanoparticles beads for hexavalent chromium removal from wastewater

Fe0 nanoparticles (NZVI) were successfully immobilized on epichlorohydrin/chitosan beads (ECH–CS–NZVI beads) for reduction of Cr(VI) from wastewater. Characterization with scanning electron microscope (SEM) showed that ECH–CS–NZVI beads with an average aperture size of 23.2 μm mainly consisted of Fe, O, C and N. Fourier transform infrared (FTIR) spectrum suggested that ECH could be grafted to CS–NZVI beads. A marked decrease in crumpling ratios indicated that the mechanical strength of Fe0-nanoparticles–chitosan (CS–NZVI) beads was obviously enhanced by cross-linking of epichlorohydrin (ECH). The thermal stability of ECH–CS–NZVI beads was also enhanced. Cr(VI) concentration, NZVI dosage, pH values and reaction temperature played an important role in the lifetime and using efficiency of ECH–CS–NZVI beads. Under all experimental conditions, the removal of Cr(VI) using ECH–CS–NZVI beads was consistent with pseudo first-order reaction kinetics. A removal rate could be maintained as high as 76.6% and 48.2% on the second and third runs, respectively, which hinted that ECH–CS–NZVI beads could be regenerated. The study demonstrates that ECH–CS–NZVI beads could become an effective and promising technology for in situ remediation of Cr(VI).

► ECH–CS–NZVI beads were prepared with high mechanical strength, offering a way to effectively use NZVI.
► ECH–CS–NZVI beads were effective to remove Cr(VI) from wastewater.
► ECH–CS–NZVI beads could be regenerated.
► ECH–CS–NZVI beads could become an effective technology for in situ remediation to Cr(VI).