Abstract: In order to solve the gravity sedimentation problem of micron iron, this paper uses xanthan gum to modify the micron iron. The stability of the modified micro iron slurry was explored through sedimentation experiments and the degradation ability was explored by removing Cr(Ⅵ) pollutant. The results show that when the dosages of xanthan gum are 0.0, 1.0, 1.5, 2.0, 2.5, 3.0, 6.0 g/L respectively, the corresponding relative spectrophotometric values are 0.05, 0.25, 0.46, 0.57, 0.65, 0.73, 0.87 at the end of 5 h sedimentation experiment. The suspension stability of the modified micro iron slurry is gradually strengthened with the increase of the mass concentration of xanthan. Xanthan has the ability to inhibit the adsorption of Cr(Ⅵ) by micron iron, which can promote the reduction of Cr(Ⅵ) and improve the removal rate. With the increase of the concentration of xanthan gum, the corresponding Cr(Ⅵ) removal rates are 33.37%, 41.23%, 47.45%, 51.05%, 52.97%, 63.91% and 64.08%, respectively. It can be seen from the results that 6.0 g/L xanthan gum modified micron iron slurry has the best suspension stability and the addition of xanthan gum improves the reactivity of micron iron. However, when the mass concentration of xanthan gum exceeds 3.0 g/L, the removal rate of Cr(Ⅵ) is not significantly improved. The greater the concentration of xanthan gum, the more obvious the buffering effect of xanthan gum.

Key words: groudwater, modified micron iron, xanthan gum, Cr (Ⅵ), pollution remediation