Electrochemical reduction of arsenic (III) with cadmium metal

The kinetics of aqueous arsenic (III) reduction to amorphous arsenic with cadmium metal are presented. Two reaction mechanisms are observed in this system. With arsenic concentrations greater than approximately 0.2 gm/1 in solutions containing one molar sulfuric acid, the reduction of arsenyl ion on the cadmium surface is rate controlling. When arsenic concentrations are less than this value, reaction rate is mass-transport controlled. The reduction of arsenic (III) with cadmium powder at pH 2 is also presented.