Anodic Behavior of Gold in Alkaline Thiourea Solution

Anodic behaviours of gold and its associated elements, such as silver, copper, and nickel and iron in a thiourea solution were investigated by using a linear potential scanning method and a detailed study was made of all factors affecting anodic polarization of gold in alkaline thiourea solution. The authors made choice of stabilizers for thiourea. The results show that provided thiourea occurs stably in the alkaline medium, selective dissoulution of gold can be achieved. Anodic potential is a critical factor affecting dissolation of gold in the alkaline thiourea solution. Excessively high temperatures and potential can cause easily irreversible decomposition of thiourea, producing elemental sulfur which can passivate the surface of gold. However, Na 2SO 3 can depress effectively the irreversible decomposition of the alkaline thiourea solution, improving greatly the polarization of gold in the alkaline thiourea solution.