Synthesis of Metallic Nanoparticles from the Recovery of Secondary Sources: An Opportunity within the Circular Economy Process

Abstract

Waste recycling as secondary source has become important from the environmental perspective and the circular economy. In this context, any waste can become raw material to manufacture other products, such as nanoparticles. Thus, this study aims to provide a descriptive and critical view of metal recovery techniques and later use them as raw materials for nanoparticle synthesis. After scoping searches, an investigation was carried out and found a gap in the research on synthesizing nanoparticles from secondary sources. The possible technologies to recover metals are hydrometallurgical processes, pyrolysis, and bioleaching followed by purification processes. The advantages and disadvantages were discussed. Based on this analysis, hydrometallurgical processing was identified as the most suitable method and, consequently, the most used method for synthesizing nanoparticles. There is a difference in the size and shapes of nanoparticles synthesized by secondary sources and commercial salts.