Chromium is mainly present in speciation of Cr(VI) and Cr(III), and it is well known that Cr(VI) is had high toxic, mobile and carcinogenic. Most common choice to handle Cr(VI) is reduction into Cr(III) with relatively low toxicity and stable state. In nature, several researchers reported that clay mineral could enhance the reduction of Cr(VI) in the aqueous phase like groundwater, however, the role or mechanisms of clay mineral on the Cr(VI) reduction was unclear. In this study, the role of clay minerals on the Cr(VI) reduction was investigated. The clay mineral does not enhance the reduction, but the ferrous leached from the clay mineral reduced Cr(VI) to Cr(III). The rate of Cr(VI) reduction was similar to that with same amounts of ferrous added into solution artificially. The acid-washed clay mineral did not reduce Cr(VI) because the acid washing removed leachable ferrous from the clay mineral. The clay minerals which do not contain any leachable ferrous could not reduce Cr(VI) at all. The reduction rate increased with the amounts of clay mineral added to solution because the ferrous leached from the clay mineral is linearly proportional to the amounts of clay mineral. Therefore, the results indicate that the role of clay mineral on the reduction of Cr(VI) is just supply of ferrous, a well known reductant for Cr(VI).<br/>

Role of clay minerals on Cr(VI) reduction

251st National Meeting (2016)

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