Advancements in the field of electronic waste Recycling: Critical assessment of chemical route for generation of energy and valuable products coupled with metal recovery

Abstract

The technological advancements in the field of electrical and electronic equipment leads to the rapid increase in the obsolescence rate of these devices and the generation of electronic waste (e-waste). The problem is further exacerbated due to the limited awareness about disposal methods of e-waste coupled with limited viable recycling avenues. Rising demand and limited recycling capacity further lead to increased resource extraction and mining activities having a degenerative impact on biota. The improper recycling and unregulated accumulation of e-waste too has its ramifications on human health, economy, and environment at large. However, e-waste is also an asset as metals and plastics account for around 75 wt% of e-waste and provide an opportunity for resource recovery. Therefore, there is a need to find a sustainable solution for resource recovery and the sound management of e-waste. Hence, this review focuses on the current technologies from the aspect of e-waste management and resource recovery i.e. chemical conversion of e-waste plastic to valuable products as well as energy generation and metal recovery from e-waste using hydrometallurgical and pyrometallurgical approaches. This review covers various technologies such as pyrolysis, catalytic pyrolysis, gasification, and supercritical fluids to recycle e-waste plastic. In addition, the recovery of metals using hydrometallurgical technologies such as cyanide, thiosulfate, thiourea, halide, and acid leaching has also been critically discussed. The pyrometallurgical approach for the recovery of metals has also been discussed. This review considers the environment-friendly approach, economic value, and recycling efficiency of the process as important parameters for e-waste recycling. Novel and greener technologies for metal recovery are suggested for the future. The review recommends an integrated sustainable solution for e-waste recycling which includes e-waste plastic recycling and metal recovery which is expected to provide guidance for future research and technology development for industrial practice.