Plastic\u2019s toughest problem may have just met its smartest solution.<\/p>\n
A team of scientists from the National Renewable Energy Laboratory (NREL), the University of Massachusetts Lowell, and the University of Portsmouth in England has unveiled a game-changing enzymatic recycling process of breaking down PET, the world\u2019s most widely used plastic.<\/p>\n
For the first time, breaking down used PET into its building blocks is not only cleaner than making new plastic from oil, it\u2019s also cheaper and has a lower carbon footprint.<\/p>\n
A smarter chemical switch<\/p>\n
Led by the U.S. Department of Energy\u2019s National Renewable Energy Laboratory (NREL) and the University of Portsmouth\u2019s Centre for Enzyme Innovation, the research introduces a subtle but pivotal chemical switch by replacing sodium hydroxide with ammonium hydroxide.<\/p>\n
That single tweak has unlocked a self-sustaining recycling loop that slashes chemical use by 99 percent, reduces energy consumption by 65 percent, and cuts operating costs by nearly three-quarters.<\/p>\n
\u201cSometimes, the key to a global challenge lies in rethinking a single chemical,\u201d said Professor Andrew Pickford, director at Portsmouth\u2019s enzyme centre and a senior author of the study.<\/p>\n
\u201cBy choosing a different base, one that could be recycled within the process, we managed to close a loop and significantly improve both the sustainability and the economics of the system.\u201d<\/p>\n
The new process tackles long-standing hurdles in enzymatic recycling. While mechanical recycling is energy-efficient, it can\u2019t handle much of the PET waste stream, such as coloured plastics, thermoforms, and textile fibres.<\/p>\n
Enzymatic recycling can break PET down to its core chemical components, but until now, high costs and environmental drawbacks have held it back.<\/p>\n
The closed-loop process brings the cost of recycled PET down to $1.51 per kilo, cheaper than virgin plastic, which currently sells for $1.87.<\/p>\n
Ammonium hydroxide not only maintained the optimal pH for enzymatic PET breakdown but also regenerated itself during the process through thermolysis of a byproduct. This nearly eliminated the need for fresh acid and base chemicals.<\/p>\n
\u201cDespite the advantages of enzymatic recycling for complex plastic waste streams, the field has encountered multiple challenges for realistic implementation. Here we have taken a multidisciplinary approach that incorporates multiple innovations to realize an economically viable and scalable process,\u201d Dr Gregg Beckham, co-lead of this study.<\/p>\n
Cracking closed-loop code<\/p>\n
In parallel, the researchers enhanced plastic pre-treatment through optimized extrusion and quenching, achieving complete depolymerization within 50 hours.<\/p>\n
The process also improved ethylene glycol recovery by increasing its concentration during fed-batch processing, boosting efficiency for this second key PET component.<\/p>\n
\u201cPET is one of the most widely used plastics in the world, and its current low recycling rates are a major environmental concern,\u201d Pickford said.<\/p>\n
\u201cThis is the first-time enzymatic recycling of PET<\/a> has looked not only environmentally preferable, but commercially viable. It\u2019s the sort of progress we need if we\u2019re serious about ending plastic pollution.\u201d<\/p>\n