Ionic liquids offer new solution to plastic recycling

Source: Xinhua| 2018-11-30 17:28:23|Editor: Lu Hui
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BEIJING, Nov. 30 (Xinhua) -- From plastic water bottles along the River Thames in the UK to plastic wrappings after China's "double 11" shopping spree, the problem of "white pollution" keeps ballooning.

Thanks to a salt in liquid state "ionic liquids," Chinese researchers from Ionic Liquids Clean Process Team (ILC), Institute of Process Engineering (IPE) under Chinese Academy of Sciences (CAS), have developed a new recycling technology to break polyester (PET) plastics down into their most basic molecules, to perpetually remake the plastic waste as its own raw material.

PET is the fourth-most-produced polymer in the world. It is widely used in daily life, in drinking bottles, carpet fibers, printable circuits, polyester fabrics and the like.

Although reducing usage and improving waste systems can put a dent in the plastics entering the environment, the rate of production is tremendous compared to its degradability.

Most recycled plastics are simply broken into pellets that are then remolded to make new plastic products of lesser quality.

The pollution caused by some traditional recycling methods is high while the efficiency is low, IPE Principal Investigator Lu Xingmei told Xinhua.

Ionic liquids have ions that refuse to stack neatly into crystals like table salt and make them exist as liquid. They stand out in the green chemistry movement because they rarely evaporate, so cannot be inhaled and do not form smog.

"Using ionic liquids as catalysts, we split the long polymer chains of PET plastics into constituent parts, increasing the final degradability to 100 percent in the lab and cutting the use of water in the recycling process by more than 75 percent," she said.

The Chinese researchers are discussing with British company Green Lizard Technologies plans to build a 10,000-tonne capacity PET plastic recycling facility in Britain.

Zhang Suojiang, director of ILC and director of IPE, believes commercializing the new technology will promote the promising future of the circular economy.

Dismantling plastics to their chemical parts provides building blocks to remake plastic products of equally high quality. Theoretically, it could lead to an infinite recycle, said Zhang.

It's still cheaper to burn plastic waste and or to throw it in landfills. The Chinese researchers are planning to make their new chemical recycling technology more economical.