Fig. 3
From: Oxidation of arsenite to arsenate on birnessite in the presence of light
Characterization of surface species after reaction: arsenic K-edge XANES spectra of HSA Na-birnessite exposed to As(III) for 8Â h under dark and light conditions. Also shown is the arsenic K-edge XANES spectrum of HSA Na-birnessite exposed to As(V) under dark conditions for 8Â h, and spectra for As(III) and As(V) solutions. (All the plots were offset for clarity)