Removal of Hexavalent Chromium Using Nanoscale Zero-Valent Iron Stabilized by Poly (?-Glutamic Acid)

Hexavalent chromium (Cr(VI)) is one of the most toxic components in heavy metal pollution. The reduction of highly toxic Cr(VI) into much less toxic trivalent chromium (Cr(III)) is a promising and common method of remediating Cr(VI) contamination. Nanoscale zero-valent iron (nZVI) is an important nanoparticle to facilitate environmental remediation. It was reported on the fabrication of a bionanocomposite (nZVI@PGA), i.e. nZVI stabilized and modified by poly (?-glutamic acid) (PGA). The bionanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The processes of Cr(VI) conversion by nZVI, PGA and nZVI@PGA were investigated and optimized. Compared to unmodified nZVI, nZVI@PGA displayed higher activity in acidic environment. The pH and PGA loading were optimized. The maximum unit removal of Cr(VI) by nZVI@PGA can reach 340 mg/g in acidic environment. The results demonstrated that nZVI@PGA can convert about 97.3 % Cr(VI) (initial concentration was 20 mg/L) in 30 min at pH=3. nZVI@PGA owns high stability and reactivity, and has potential to remove Cr(VI) of sewage in the future.