硫酸根离子强化零价铁去除Cr(Ⅵ)的试验研究

Generally, zerovalent iron (ZVI) is considered to have low intrinsic reactivity toward Cr (VI) removal, and on the other hand, Cr (VI) could also cause surface passivation of ZVI. To address this issue, sulfate was introduced into a ZVI column system and its effect on ZVI performance and the corresponding mechanisms was investigated in depth. According to the results of this work, without the presence of SO₄ ^2-, little Cr (VI) could be removed by ZVI column, and the effluent concentrations of Cr (VI) and total Cr would quickly exceed the maximum contaminant limitation of drinking water. While, upon the addition of 1~3mmol/L SO₄ ^2-, both the concentrations of Cr(VI) and total Cr deceased rapidly and met the drinking water standards. Furthermore, this good ZVI performance kept unchanged during the following running time (~240h) in this work, and more longer duration could be expected. The XPS analysis of the reacted ZVI samples indicated Cr(VI) could be reduced to Cr(III), implying Cr(VI) reduction was its main removal mechanism by ZVI. With respect to the role of SO₄ ^2-, it was believed to be able to accelerate ZVI corrosion and thus enhance the Cr(VI) reduction.