“…Every year, the amount of discarded computer equipment around the world increases [25], which triggers the exponential growth of the "e-waste", including PCBs, so it is necessary to accelerate the research to develop an optimal process for the recovery of the PCBs, which can be environmentally friendly, compatible with hydrometallurgical processes and more cost-efficient, and which involves the use of sulfuric acid and oxygen, in comparison with those implicating the use of nitric acid, hydrochloric acid, peroxides and even aqua regia, as they are potential sources of pollution and health risks [26]. An optimum mechanism for the recovery of metal products is to submit them to the process of acid leaching using oxygen and sulfuric acid (pH 1.5) to dissolve the copper, nickel and zinc, with later gold retrieval [11,12,27].…”