Direct electrochemical reduction method for removing selenium from wastewater

Abstract

Methods for selenium removal from wastewater are provided using direct electrochemical reduction. Advantageously, the technique can efficiently and continuously treat weakly acidic wastewater (pH 4-7) with 0.001-10 mM Se(IV) concentrations in a weakly acidic solution. Embodiments of the invention include Se(IV) electrochemically removed from the aqueous phase through either a four- or six-electron pathway, with the former generating Se(0) directly attached to the electrode surface and the latter producing Se(-II) that is subsequently converted to Se(0). A key feature of these embodiments is the use of moderate heating to ensure the process takes place at an elevated temperature (e.g., temperatures above the amorphous-to-crystalline transition for Se(0)), which the inventors discovered results in the creation of conductive crystalline Se on an electrode surface, thereby avoiding self-limiting nature of prior techniques which result in insulative amorphous deposition of Se(0) on the electrode.

Dependencies are inferred from the claim text.