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Efficient Recycling of Polylactic Acid Using an Enzyme Found in Laundry Detergent!

May 29 , 2024

According to recent information provided by King's College London, scientists at King's College London have developed an innovative solution for recycling disposable bioplastics. They utilize an enzyme commonly found in laundry detergent to chemically recycle polylactic acid (PLA) within 40 hours. PLA is typically used in items like straws and food containers.

This new chemical recycling method was published in the journal Cell Reports Physical Science.

photo by《Cell Reports Physical Science》website

The researchers developed a depolymerization technique for PLA using ionic liquids. Ionic liquids are organic salts with a melting point below 100°C. It is known that enzymes required for depolymerizing plastics have low tolerance to ionic liquids and are generally insoluble in them.

The researchers began searching for an enzyme suitable for this task. They selected Candida antarctica lipase B (CaLB), a widely used enzyme commonly found in laundry detergent. The researchers chemically modified it to be soluble and stable in ionic liquids.

The modified enzyme was dissolved in the ionic liquid, and fragments of PLA plastic cups were soaked in the solution. The plastic fragments completely dissolved into the solution within 24 hours and, at 90°C for another 16 hours, fully degraded into the plastic's constituent parts—lactic acid. Lactic acid can be used to manufacture more plastic or other chemicals.

Dr. Alex Brogan stated, "We are now working with engineers to see how to improve this process through more precise pretreatment, such as grinding, which will allow us to work on a larger scale. The main improvement we need to demonstrate is that you can actually use the degraded plastic to manufacture plastic again, creating a closed loop."