A method for precipitating arsenic from a solution

The present invention relation to an electrochemical process for precipitating arsenic from a liquid formulation containing one or more of As(III) and As(V) ions or a mixture thereof, in the form of crystalline scorodite FeAsO4.2H2O particles, wherein the process comprises the steps of (i) supplying the formulation to a catholyte in a cathode compartment of an electrochemical cell equipped with a cathode comprising a gas diffusion electrode with a porous electrochemically active material, and adjusting the pH of the thus obtained catholyte EP 3 674 446 A1 to a value of between 0 and 2.0, which cathode compartment further contains a source of Fe ions in an amount which is such that the molar ratio in the catholyte of Fe ions to As ions is minimum 4.0;

(iii) supplying an O2 containing oxidant gas to the gas diffusion electrode; (iv) applying a potential to the cathode which is such as to cause reduction of the O2 contained in the oxidant gas to one or more of the corresponding peroxide, OH-, ionic and/or radical reactive oxygen containing species and (v) recovering precipitated, crystalline scorodite.