Source: Academic Headlines
In 1907, The Belgian-American chemist Leo Baekeland invented a cheap, non-flammable general-purpose plastic, known as Bakelite. This invention marked the beginning of the modern plastics industry, and Baekeland was known as the "father of plastics".
But plastic, once known as one of the greatest inventions of the 20th century, is now considered one of the most failed inventions, and it is ubiquitous, bringing great convenience to human life while seriously polluting the earth's home on which we live.
Even more frightening is that this rugged material often takes hundreds of years to degrade.
The problem is, if the degradation time of hundreds of years is shortened to a few days, or even a few hours, like this:
So, can the problem of "white pollution" be solved?
Today, research teams from The University of Texas at Austin and DEVCOM ARL-South offer a new way of thinking about solving the world's most pressing problem, "white pollution."
With the help of artificial intelligence technology, the research team has invented a new type of enzyme that has the potential to promote the large-scale recycling of PET plastics (a kind of plastic, common language for beverage bottles, films, packaging, etc.), and recycling and reusing plastics at the molecular level can greatly reduce unnecessary environmental pollution.
The research paper, entitled "Machine learning-aided engineering of hydrolases for PET depolymerization," was published in the authoritative scientific journal Nature on April 28.
(Source: Nature)
Biological enzymes created by artificial intelligence
Plastic, which is already used in every aspect of our daily lives, is a necessity that we can hardly leave. But poorly managed plastic waste can pollute the ecological environment on land and at sea.
Theoretically, this problem can be avoided by plastic recycling, but the recycling of many plastics is not simply mechanical recycling, but involves melting and reprocessing, the process is very complicated, and the quality of the new plastic produced is not as good as the original plastic.
PET plastic is a common and safe plastic in daily life, accounting for 12% of the world's plastic waste, and is mostly found in applications such as synthetic fiber production, food-containing containers and thermoforming.
PET plastics can be recycled by being broken down into molecular-grade monomers, but the standard chemical depolymerization process is energy-intensive and requires large amounts of alkalis and acids, so it is not economically or ecologically feasible.
Another potential solution is the use of enzymes, which have led to much progress in research on plastic recycling enzymes over the past 15 years, but so far scientists have not found enzymes that work efficiently at low temperatures and cannot be used in large-scale industrial production, hindering the development of this recycling strategy.
In this work, the researchers used machine learning models to predict which mutations in the new enzyme could allow discarded plastics to break down quickly at low temperatures, and they tested them on 51 plastic containers, 5 different polyester fibers and fabrics, and all water bottles made of PET plastic, and demonstrated the effectiveness of the enzyme.
Figure | improve the performance of enzymes with the help of machine learning methods (Source: the paper)
This enzyme enables the closed-loop recycling of PET plastics, which can break down plastic into smaller monomers at temperatures below 50 degrees Celsius and then chemically repolymerize them. In some cases, PET plastic can be completely decomposed within 24 hours.
The research team says potential applications for the enzyme include cleaning up landfills and doing environmental remediation. They plan to expand the production of this enzyme in future work for use in large-scale industrial production.
How much do you know about plastic?
Plastic refers to a high molecular weight synthetic resin / petroleum as the main component, the addition of appropriate additives, such as plasticizers, stabilizers, antioxidants, flame retardants, lubricants, colorants, etc., processed and molded plastic (flexible) materials, or cured crosslinking to form a rigid material.
Plastic garbage is difficult to decompose naturally, if it flows into the ocean, it will lead to accidental ingestion, suffocation, poisoning, etc., affecting the marine ecology; incineration of plastic waste will also cause air pollution, polyvinyl chloride (PVC) and polycarbonate (Polycarbonates) and other plastics, and even under certain conditions will release harmful substances or endocrine interferons, endangering the reproductive function of organisms.
So, what types of plastics are included? What are their uses? Xuejun summarized some common plastics and special plastics for the reader's reference:
1. Common plastic types and uses
Polyethylene terephthalate (PET): beverage bottles, films, packaging.
Polypropylene (PP): Food packaging, household appliances, auto parts (e.g. safety rods).
Polystyrene (PS): Packaging materials, food packaging, disposable cups, plates, cutlery, CD and DVD folders.
High impact polystyrene (HIPS): Packaging materials, disposable cups.
ABS resin/Acrylonitrile butadiene styrene (ABS): Covers electronic devices (e.g., monitors, printers, keyboards).
Polyester (PES): fibers, textiles.
Polyamides (PA): Fiber production, golf balls, fishing lines, automotive coatings.
Polyvinyl chloride (PVC): pipe fittings production, shower curtains, window frames and floor coverings.
Polyurethanes (PU): foam insulation, fire protection, fire extinguishing foam.
Polycarbonate (PC): Discs, sunglasses, protective covers, safety glasses, indicators, lenses.
Polyvinylidene chloride (PVDC): Packaging (such as food and pharmaceuticals).
Polyethylene (PE): film, packaging bags (generally common plastic bags), filling bottles (such as shower gel, detergents), water pipes.
Polycarbonate/Acrylonitrile Butadiene Styrene (PC/ABS): A blend of PC and ABS plastics for more robust use in automotive interiors and exterior accessories, mobile phone cases.
2. Other types of plastics and uses
Polymethyl methacrylate (PMMA): Contact lenses, glass (such as plexiglass).
Polytetrafluoroethylene (PTFE): Heat-resistant, low-friction coatings: non-stick-free pots, sealing tapes for plumbers, waterslides in playgrounds, etc.
Polyetheretherketone (PEEK): Chemical and thermoplastic resistant, high biocompatibility, use of medical implants, aerospace products.
Polyetherimide (PEI): High temperature resistant, chemically stable, non-crystalline polymer.
Phenolic resin (Phenolics, PF): Commonly known as bakelite, high modulus, relative heat resistance, fire resistance and excellent polymer. Used in electrical equipment insulation parts, paper laminated products, thermal insulation foam materials.
Urea-formaldehyde (UF): tableware, ornaments, electrical parts, distribution appliances, telephone handsets, auto parts, plywood, adhesives, coatings, buttons, containers, mahjong cards, hour hand plates, chopsticks, clothing buckles, bottle caps, etc.
Melamine formaldehyde (MF): resin processing of glass, tableware, ornaments, electrical accessories and shells, switchboards, mechanical parts, auto parts, liguang boards, coatings, adhesives, containers, paper, cloth.
Polylactic acid (PLA): A molecule that can be broken down by microorganisms and converted by corn starch. What is currently available on the market is a transparent box for water eggs.