Evaluation and Comparative Analysis of Heavy Metal Leaching Efficiency by Nitric Acid, Perchloric Acid and Sulfuric Acid from Moroccan Phosphate Solid Waste

This article presents a comprehensive study into the leaching of heavy metals such as Al, As, Cd, Cu, Zn, Ni, Fe and Cr from Moroccan phosphate solid waste. Sulfuric acid, perchloric acid and nitric acid were used as leaching agents at various concentrations (0.5 M, 1 M, 2 M, 3 M and 4 M) under ambient temperature conditions, maintaining a particle size of 160 µm and a stirring time of 1 hour. To optimize the efficiency of metal extraction, research focused on the subtle interplay between acid selection and concentration. Nitric acid appears as the front runner, consistently showing excellent leaching results for all metals, especially at higher concentrations. Although perchloric acid does not exceed the efficiency of nitric acid, its performance is competitive and position it as a viable alternative, with encouraging results, especially at moderate concentrations. Sulfuric acid shows different trends in metal leaching efficiency, highlighting the need for separate and customized approaches. At lower concentrations it shows moderate effectiveness, with leaching efficiency varying depending on the metal. As acid concentration increases, extraction efficiency changes, requiring careful consideration of specific metal properties. In the hierarchy of leaching agents, the position studied is nitric acid > perchloric acid > sulfuric acid, indicating the superior performance of nitric acid, followed by perchloric acid, compared to sulfuric acid during metal leaching.