Synthesis of ZnO nanopowder using zinc Zamak dross and adsorption of Pb

Abstract

In this study, zinc oxide nanopowder (ZnONPDs) was successfully recovered from zinc die casting alloys’ (ZAMAK) dross using a facile dissolution and pH-controlled precipitation approach for removal of lead (II) ions from aqueous solutions. XRD patterns showed that ZnONPDs, calcined at 240°C, exhibited a hexagonal unit cell structure with an average crystallite size of 36.46 nm. FE-SEM micrographs revealed that the ZnONPDs are spherical and hexagonal in shape. TEM images showed the morphology and particle size of synthesized ZnONPDs with an average size of 23.81 nm. XRF and EDS analyses confirmed the high purity of the prepared ZnONPDs. The BET surface area of ZnONPDs was 33.85 m²/g. Adsorption experiments exhibited the maximum removal of Pb2+ ions 100% at the optimal conditions (25 ppm Pb2+ ions, 20 min contact time, 30 mg adsorbent per 100 ml of solution). The pH and zeta potential confirmed that a pH range from 5 to 9 was optimal for the adsorption study. The zeta potential within this range indicated a high level of stability for the particles in the suspensions, effectively preventing flocculation and agglomeration. XPS results conclusively demonstrated the successful adsorption of Pb onto the surface of ZnONPDs. The ZnONPDs synthesized in this study were shown to be promising candidates for use in adsorption processes, indicating that they could be highly useful in wastewater treatments removing toxic metal ions.