Study on the mechanism of distribution, preservation and occurrence state for the remediation of Cr(VI) from chrome slag soil-water belt

Abstract

The pollution of Cr(VI) in chrome slag soil-water belt is a very serious pollution problem due to industrial expansion in China. In this paper, the transmission characteristics of stabilizing nanoscale zero-valent iron (nZVI) in chrome slag soil-water belt are investigated by carrying out a simulatively penetrating experiment, in which use of soil column is made for ， the elution process test of Cr(VI), the long-time maintained experiment and the chemical state analysis of Cr in the washed soil column. The results showed that the chrome slag soil-water belt-a and c were liable to be penetrated. The chrome slag soil-water belt-b had relatively slow penetration rate. The concentration of Cr(VI) in the leachate in the long-time maintained experiment was bigger than short-time test. When the reaction proceeded with 0.37g/L of nZVI, the final fixed rate of Cr(VI) in the chrome slag soil-water belt-c was 97.55%. It makes sense to use excessive nZVI to maintain the reducing effect of reaction system. On the whole, distribution of Cr in various states is different in different soil samples. The residual state accounts for the largest proportion, followed by the adsorption state and the organic combination state. The residual state increases with the depth of soil column. For the carbonate bounded state, it reaches maximum proportion at mid-depths. However, the proportion of organic bounded state keeps decreased with the increase of soil depth. The research results in this paper provide an important reference for the practitioner regarding the remediation of soil and groundwater pollution.