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The ARC Laureate project primarily involved high temperature transformations of e-waste over a multi-year period at the UNSW SMaRT Centre. This work helped to establish crucial steps in SMaRT's microrecycling science journey.
Researchers using various thermal processes discovered that synthesis of materials from waste is possible by enabling multiple reactions to harness the selective properties of various materials.
This help lay the foundations for the development of novel microrecycling pathways to generate different materials from complex waste, using high temperature transformations.
Melting, degradation, diffusion or evaporation of different materials are triggered at various temperatures and times. By activating various micro mechanisms, such as, 'thermal micronizing' and 'nano wiring', enables the selective synthesis of materials from macro to nano scales at temperatures ranges of between 400-1550o C.
For instance, selective synthesis of materials makes it possible to transform glass and plastic together through 'thermal nano-wiring' at high temperature which generates ceramic products such as silicon carbide nanowires, which have a range of industrial applications.
In another example, the glass fraction of e-waste (a rich source of silica SiO2) and carbon obtained from waste tyres, have been extracted through a fast heating technique to synthesise excellent quality nano-scale SiC. Researchers also synthesised manganese oxide MnO and zinc oxide ZnO nanoparticles from spent batteries via their 'thermal nano-sizing' technique.
Why are these breakthroughs important?
The global supply of rare earth elements (REEs) is under considerable strain, so the recovery of REEs from e-waste is strategically vital.
The selective thermal isolation techniques at SMaRT make it possible to recover these and other the rare earth oxides (i.e., Nd, Pr and Dy) from permanent Nd-Pr-Dy magnets sourced from e-waste.
Using outdated computer printed circuit boards (PCBs), SMaRT is able to selectively transform them into various metallic alloys via thermal transformation, such as copper-based tin, zinc, lead alloys.
For the first time, the SMaRT Center invented the direct production of value-added nano particles of metal alloys from selective thermal transformation where degradation of the waste plastics of circuit board created a reducing environment to enhance the processing at relatively low temperatures.
Professor Sahajwalla is the recipient of an Australian Research Council Georgina Sweet Australian Laureate Fellowship. This Fellowship supports her project in e-waste research and her
Science 50:50 program to inspire young women into science.