Co-transport of Cr(VI) and Bentonite Colloid in Saturated Porous Media.

Transport of Cr(VI) at the presence of bentonite colloid was carried out in saturated porous media of 16–18 mesh and 40–60 mesh sand columns. Effects of flow rate, pH, ion strength, humic acid and bentonite concentrations on Cr(VI) migration were investigated. The results show that the increase of flow rate accelerated the breakthrough of Cr(VI) and BP, but the transport mass of dissolved Cr(VI) decreased by ~ 15.0% when flow rate increased to 2.5 ml min−1. Increasing IS to 10mM resulted in decrease of Cr(VI) transport mass by 6.86%–21.4%. Increase of pH and decrease of bentonite concentration favored the transport of dissolved Cr(VI). Humic acid had little effect on transport amount of Cr at pH7. Cr(VI) transport was dominated by the dissolved Cr(VI). The transport data of dissolved Cr(VI) were well described by the two-site model. The presence of BP reduced total Cr(VI) transport mass in co-transport.