| Abstract |
Electrical and electronic components, the silent orchestrators of our technological symphony, have been crucial for enabling societal advances. From the simple beginnings of vacuum tubes to the complex circuitry in today's smartphones, the role and type of electronic components have continued to evolve. The components of electrical and electronic equipment once it has reached the end of its useful life as a product are called electronic waste (e-waste). The exponential growth of electronic devices has made e-waste management an important environmental issue. Improper disposal of e-waste to landfills has serious environmental consequences for the global ecosystem. The majority of discarded e-waste such as computers, mobile phones, televisions, printers, and so on, are embedded with printed circuit boards (PCBs), which are an essential and basic component. PCBs of e-waste contain many different metals including precious metals (Ag, Au, Pd, Pt, etc.), critical elements (Li, Ni, Ga, graphite, rare earth elements, etc.) and non-critical metals (Al and Fe) in varying percentages depending on the electronics. In the emerging era of circular economy recycling, waste printed circuit boards (wPCBs) of any e-waste are seen as an alternative to processing mining ores to meet future metals demand. Different recycling methods such as mechanical separation, pyrometallurgy, hydrometallurgy, biohydrometallurgy, pyrolysis, electrolysis and supercritical fluid technologies have been explored to extract the valuable metals from e-waste. This article aims to provide a critical review of the different recycling routes for e-waste, with a focus on the emerging supercritical fluid technologies (SFT), and their opportunities and challenges. This review will compare the emerging SFTs for existing processes used in industry and other alternative treatment methods. The specific areas of comparison include technical complexity and environmental impacts. |