**1. Introduction**

The electronics industry is the largest and fastest-growing manufacturing sector in the world. The PCBs are waste sources from electronic machines such as television boards, CD players, and cell phones. Researchers have reported that in recent years,

the average rate of PCB development has risen by 8.7% due to technological progress. The studies observed that the continuous increase in e-waste generation rates is due to the nation's population and technological growth. The studies predict that each individual would produce approximately 5173 kg of e-waste per year. The metallic composition consists primarily of 10–30% of copper (Cu) and other metals such as tin (Sn), zinc (Zn), lead (Pb), nickel (Ni), iron (Fe), silver (Ag), cadmium (Cd), gold (Au) and others, depending on the sources of printed circuit boards (PCB) [1–3]. A sample PCB is shown in **Figure 1**. Informal processing of e-waste in developing countries can lead to adverse effects on human health and environmental pollution. In 2016, 44.7 million metric tons of e-waste were generated globally [4, 5]. Health symptoms like headaches, dizziness, irritation in the eyes, nose, mouth, etc. are caused by exposure to Cu, which is present in landfills [6–8]. The methods that can be used to recover metals from PCBs are essentially physical, mechanical and chemical separations. Several studies on the feasibility of metal recovery from PCBs have been investigated in the last decade. Hydrometallurgical procedures, such as leaching, are very intentional in these studies.
