Cu(II) Removal from lithium bromide refrigerant by chemical precipitation and electrocoagulation

A combination of chemical precipitation and electrocoagulation was used to remove Cu(II) from lithium bromide refrigerant, and factors affecting the treatment efficiency were also studied. The corrosion inhibitor, Li2CrO4, was first precipitated from the refrigerant by reaction with Ba(OH)2, which also increased the refrigerant alkalinity to 30.0 meq/L. Significant Cu(II) and Fe(II,III) removals also occurred through adsorption and co-precipitation. The pretreated refrigerant was further treated in an electrocoagulation cell using iron electrodes, where Cu(II) removal occurred through coagulation, adsorption on and co-precipitation with ferrous and ferric hydroxides. Fe(II,III) concentration and alkalinity of the refrigerant did not change significantly during the electrochemical treatment. The optimal laboratory electrocoagulation conditions for the pretreated refrigerant were: current density at 4.0 mA/cm2 and for 3.0 min. Up to 98.5% of Cu(II) in the contaminated refrigerant could be removed by the combined treatments.