Abstract: An experiment was carried out on nanoscale zero-valent iron (NZVI) reducing Cr(Ⅵ) in water to explore effects of NZVI application rate, initial concentrations of Cr(Ⅵ), initial pHs, and organic acids on the reduction. It was found that NZVI efficiently reduced Cr(Ⅵ) in water at a rate 7 and 13 times higher than that of iron powder and filings, respectively. Under the condition of the initial concentration of Cr(Ⅵ) being 20 mg•L^-1 and the NZVI application rate being 5g•L^-1, the reduction rate reached 82% after 24 h of incubation. Low pH solution pH promoted corrosion of NZVI, which raised Cr(Ⅵ) reduction rate.The highest reduction rate occured in solution being 3.0 in pH. Among organic acids, oxalic acid, malonic acid and succinic acid all significantly improved the effect of NZVI reducing Cr(Ⅵ), and followed the order of oxalic acid > malonic acid > succinic acid.

Key words: nanoscale zero-valent iron (NZVI), hexavalent chromium, reduction, influencing factor