University of Bath scientists have developed a new and simple method for upcycling plastic waste at room temperature, making the process more economically viable than before.
According to the team from Bath’s Center for Sustainable and Circular Technologies (CSCT), their mild and rapid chemical recycling process is best suited for polycarbonates, a robust class of plastics commonly used in construction and engineering.
The scientists note that they were able to completely break down commercial poly(bisphenol A carbonate) (BPA-PC) beads within 20 minutes at room temperature using a zinc-based catalyst and methanol.
The waste can then be converted into its chemical constituents, namely bisphenol A (BPA) and dimethyl carbonate (DMC), helping to preserve product quality over an infinite number of cycles.
BPA recovery prevents leakage of a potentially damaging environmental pollutant, and DMC is a valuable green solvent and building block for other industrial chemicals.
According to the scientists, the new catalyst is also tolerant to other commercial sources of BPA-PC (e.g. CD) and mixed waste feeds, increasing industrial relevance, whilst being amenable to other plastics (e.g. poly(lactic acid) (PLA) and poly(ethylene terephthalate) (PET)) at higher temperatures.
The team has also demonstrated a completely circular approach to producing several renewable poly(ester-amide)s (PEAs) based on terephthalamide monomers derived from waste PET bottles.
These materials have excellent thermal properties and could potentially be used in biomedical applications, for example drug delivery and tissue engineering.
The Bath research is significant as plastic waste residing in either landfill or the natural environment currently outweighs all living biomass (4 Giga tonnes).
No doubt, recycling rates are increasing across Europe, but traditional methods remain limited because the harsh re-melting conditions reduce the quality of the material each time it’s recycled.
According to the CSCT team, their technology has only been demonstrated on a small scale so far.
They are however working on catalyst optimization and plan to scale up the process (300 mL) with collaborators at the University of Bath.
Image and content: Pixabay/University of Bath