Abstract: The application of nanoscale zerovalent iron (nanoFe0) in contaminated groundwater is fast developed for environmental remediation in recent years. However, the reactivity of nanoFe0 is impacted by different environmental factors. Among them, the ubiquitous natural organic matter (NOM) is an important issue. Herein, humic acid (HA) is taken as a model of NOM and batch experiments were conducted on the effect of HA on the removal of Cr(Ⅵ) from water by nanoFe0. The results showed that the presence of HA could significantly mitigate the reaction rate and removal efficiency of Cr(Ⅵ), which is due to the adsorption of HA onto nanoFe0 and the decrease of active sites on the surface of nanoFe0. In addition, the dissolved oxygen could enhance the removal of Cr(Ⅵ) by nanoFe0. The interaction of HAnanoFe0Cr(Ⅵ) could provide theoretical and practical value for further revealing the mechanism of remediation systems.

Key words: humic acid, nanoscale zerovalent iron, hexavalent chromium, groundwater remediation, dissolved oxygen