Selective leaching mechanisms of zinc from industrial waste using hybrid acids: Sustainable synthesis of Nano-ZnO.

Zinc-containing dust (ZCD) has received extensive attention because it is a hazardous waste rich in various metals. This study innovatively proposed a hybrid acid leaching agent based on malic acid (MA) and sulfuric acid to selectively extract Zn from ZCD and successfully prepare nano-ZnO materials. The leaching experiments show that among the combinations of various organic acids and sulfuric acid, MA and sulfuric acid are superior in the selective leaching of Zn. Under optimal conditions, the leaching ratios of Zn, Pb, and Fe are 97.70%, 0.88%, and 2.95%, respectively. In addition, the use of hybrid acids can reduce sulfuric acid consumption by more than 46%. The Molecular dynamics simulation indicate that the interaction between the hybrid acid with ZnO and PbO was stronger (PbO > ZnO > FeO). The radial distribution function (RDF) reveals that Zn and Pb ions form strong coordination structures with some oxygen atoms in MA, thereby confirming that MA plays a crucial role in preventing the dissolution of Fe. Finally, spherical nano-ZnO with a purity of 98.14% and an average particle size of 68.60 nm is obtained from the leaching solutions by precipitation method. This study provides a green and sustainable alternative for the selective recovery of Zn from ZCD.