Fig. 2
From: Oxidation of arsenite to arsenate on birnessite in the presence of light
On/off cycling of light effects on As(III) oxidation: As(V) production resulting from a As(III)/birnessite suspension at pH 5 under oxic conditions. The open symbols indicate times that the suspension was exposed to light and the closed symbols indicate times where the light was turned off. Even at relatively long reaction times light enhances the formation rate of As(V)