Environmental chemistry

Contamination

Nuclear chemistry

Adsorption

Organic chemistry

Inorganic chemistry

Chemistry

Ecology

Ferrous

Iron oxide

Chromite

Hexavalent chromium

Pyrolysis

Zerovalent iron

Chromium

Environmental remediation

Silicon

Biochar

Biology

Chemosphere

Silicon-rich biochar-supported nanoscale zero-valent iron (nZVI) was studied to evaluate enhanced removal of hexavalent chromium (Cr(VI)) in solution. The compositional structures of the nZVI and biochar-supported nZVI were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction and X-ray photoelectron spectra before and after Cr(VI) reaction. The removal amount of Cr(VI) by nZVI-RS700 (rice straw pyrolyzed at 700 °C) was considerably greater than that by nZVI and other biochar-supported nZVI samples. Upon the silicon was removed from RS700 (nZVI-RS700(-Si)), a significant decreased removal of Cr(VI) was observed. It was revealed that nZVI supported by silicate particles of biochar and the promotion of iron oxidation by SiO2 both contribute to the enhanced Cr(VI) removal. We found that the reduction and adsorption both contributed to the removal of Cr(VI), ferrous chromite (FeCr2O4) was observed on the surface of the nZVI-RS700 composite. The formation of FeCr2O4 is attributed to the reduction of Cr(VI) by nZVI and the adsorption of chromium oxide with iron on the surface of RS700. Therefore, RS700-supported nZVI can be used as a potential remediation reagent to treat Cr(VI)-contaminated groundwater.

Enhanced removal of Cr(VI) by silicon rich biochar-supported nanoscale zero-valent iron