Se can be then separated from the copper by oxidization, and distillation and evaporation of the remaining liquor yield a mixture of ZnO and InO. According to [66], sodium carbonate is the preferred agent to precipitate Cd and Te from the sulfuric acidic etchant effluent from the leaching process as it is less expensive, readily available and non-toxic. Wang and Fthenakis proved ion- exchange to be effective for separating Cd from Te in sulfuric acid media [61,62,71] (see Table 3).