Value-added products from thermochemical treatments of contaminated e-waste plastics
Résumé
The rise of electronic waste (e-waste) generation around the globe has become a major concern in recent times and their recycling is mostly focussed on the recovery of valuable metals such as gold (Au), silver (Ag) and copper (Cu) etc. However, a significant weight fraction of e-waste consists of plastics (25-30%) that are either discarded or incinerated. There is a growing need for recycling of these e-waste plastics majority of them are made from high-quality polymers (composites) such as acrylonitrile butadiene styrene (ABS), high impact polystyrene (HIPS); polycarbonate (PC); polyamide (PA); polypropylene (PP); and epoxies. However, these plastics are contaminated with hazardous materials such as brominated flame retardants (BFRs) and heavy metals (such as lead and mercury). Under any thermal stress, the bromine element (Br) present in the e-waste plastics produces environmentally hazardous pollutants, such as hydrogen bromide or polybrominated diphenyl ethers/furans (PBDE/Fs). The discarded plastics can lead to the leaching of toxins into the environment. Therefore, removal of the toxics chemicals from the e-waste plastics is prerequisite before considering any thermal process. This review article gives a detailed account of e-waste plastics recycling and recovery using thermochemical processes, such as extraction and pyrolysis. A basic framework of the existing processes has been established by reviewing the most interesting findings in recent times and the prospects that they open in the field recycling of e-waste plastics.
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