The reduction of chromate ions by Fe(OH)(2) and the iron (II)-iron (III) hy
droxysulphate green rust, GR(SO42-), was studied to evaluate whether such s
ynthetic layered hydroxides and the corresponding natural green rust minera
l could be involved in the natural attenuation of contaminated environments
. The resulting Cr (III) bearing phases, which would govern the subsequent
behaviour of chromium, were clearly characterised. Both compounds proved to
be very reactive and oxidised instantaneously while chromate ions were red
uced to Cr (III) as evidenced by X-ray photoelectron spectroscopy. Mass bal
ance (ICP-AES) demonstrated that the Fe/Cr ratio inside the solid end produ
ct was equal to the initial Fe/Cr ratio. The solid phases, analysed by X-ra
y diffraction, Raman and Mossbauer spectroscopies were identified as Cr-sub
stituted poorly crystallised iron (III) oxyhydroxides in both cases, more p
recisely delta-FeOOH when starting with Fe(OH)(2) and ferrihydrite when sta
rting with GR(SO42-).