| Popis: |
Rapid urbanization, a general improvement in living standards and increased consumption has resulted in the generation of unprecedented amounts of waste in recent years. E-waste contains over 1000 different substances; some are toxic and hazardous, which cause serious problems to the environment and on human health, hence sustainable and eco-friendly approach should be adopted to substantially recycle the e-waste. Printed circuit boards (PCBs) is prevalent in almost all of the electronic components and it is majorly categorised into FR-2 (single/double sided PCBs) and FR-4 (multi-layered PCBs). The substrates in FR-2 types are composed of phenol formaldehyde or paper-based cellulose materials. FR-4 substrates comprise of glass fibers- epoxy resins. The PCBs is always an interesting component for recyclers as it contains more than 28-30% metal. While recycling, the metallic elements are dismantled and reused for its material value, however non-metallic elements are left untreated because of its complex amalgamation. This unprocessed non-metallic waste PCB is either incinerated or landfilled leaving all the toxic elements. These toxic elements release obnoxious gases polluting the air, land and water. In this thesis, sustainable and novel processes have been developed to recycle non-metallic portions of waste PCBs into value-added products. High-temperature kinetics, thermal behaviour studies, structure and elemental compositions of PCB wastes of computer monitor and CPU were investigated. The results signify the presence of high rich carbon and glass fiber in non-metallic residues of monitor and CPU PCBs. Value-added products such as activated carbon electrodes for supercapacitor application, glass fiber-nano silicon carbide composite, lightweight aggregates and composite panels were produced from the non-metallic waste of PCBs. Sustainable and eco-friendly recycling approaches developed in this thesis provide an opportunity to recycle and utilise complex non-metallic PCB waste. |
