A multi-directional approach to e-waste plastics recycling: Ironmaking, aromatic oils and energy storage

Electronic waste (e-waste) is growing at an accelerated rate and is regarded as an aggravating economic, environmental, and social health problem globally. It’s a complex waste containing precious and toxic metals, plastics etc. which if recycled properly, can provide a range of environmental and economic benefits. Majority of the current technologies are focused solely on high-value precious and base metal recovery. Despite accounting for large proportion of e-waste, recycling of plastics has suffered, mainly due to lack of economic incentives in their recovery which is further exacerbated by their complex chemical composition and presence of harmful additives. Consequently, plastics have generally been landfilled/incinerated leading to pollution and resource depletion.This thesis aims at addressing this scenario and encompasses the development of several novel processes to recycle e-waste plastics. It demonstrates how their secondary use may potentially divert them from landfills and contribute to many high-end value-added applications such as energy storage. Styrene acrylonitrile type plastics from end-of-life printers (provided by an e-waste recycler in Sydney) were selected for this work.Firstly, the plastics were used as carbon source/reductant to extract iron from another low-value and Fe3O4-rich component of e-waste i.e. toner powder. A qualitative mechanism was proposed for the reduction of iron-oxide to metallic iron. Next, hydrocarbon oils with high calorific values (38.27 MJ/kg) were generated via non-catalytic thermal transformation of plastics. These oils were characterised using gas chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy followed by detailed qualitative mechanism for the formation of major oil components such as styrene, toluene, and naphthalene. The solid carbonaceous residues obtained from thermal transformation process were activated at 700-900 oC to produce porous activated carbons. Supercapacitor electrodes p