According to a report on October 10th, Beijing time, according to foreign media reports, due to the excessive use of human beings, about 8 billion tons of plastic waste has been accumulated in the surface and the ocean. It is no wonder that plastics have been poor in recent years.
But the importance of plastics is also beyond doubt. The invention of plastic revolutionized life in the 20th century. It is durable, versatile, and hygienic. Such materials are almost non-existent in nature. Without plastics, we would never be able to make records, tapes, movie films, etc. Naturally, we would not be able to record music, film movies, or develop modern medicine. Auto parts, light aircraft materials, satellites and spaceships also rely on plastics, making global travel and space exploration possible, not to mention computers, mobile phones and various network technologies. Look around. If there is no plastic, our life will be difficult.
Despite the importance of plastics, the disposal of plastics has always been a difficult issue. Not only that, the source of plastics is also a headache. Plastics are made from fossil fuels, and about 40% of the oil and natural gas consumed by humans each year are used to produce plastic polymers. It may not sound like much, but it still involves fossil fuel mining and climate change.
Bioplastics-does it sound so good?
Do we have alternatives? Bioplastics such as polylactic acid (PLA) are now a development area that many people are focusing on, such as disposable tableware made of potatoes, plastic bottles made of corn, garbage bags made of food waste, etc., although it sounds It seems like an ideal solution, but the fact is far from simple. First of all, bioplastics are not as easily degraded as they sound, and generally require industrial processing. Not only that, the production of bioplastics also requires a lot of energy, and the carbon dioxide emissions from harvesting crops and processing raw materials are even greater than traditional plastics.
Foreign researchers recently investigated the environmental impact of the production of plastic bottles from various materials, including corn and recyclable polyester, and found that the performance of bioplastics is not satisfactory.
Taking into account the cost of fertilizers, transportation and harvesting costs, the benefits of plastics made from biological materials are the worst, and the best performers are plastics produced from crude oil. The researchers said this was not the result they wanted to see.
The water and fertilizers used to produce bioplastics will also pollute rivers and estuaries, leading to eutrophication of water bodies. In addition, if people accidentally throw biological waste into recyclable waste, these substances will pollute the entire recycling chain. Reduce the quality of recycled plastics.
So from the current point of view, the performance of bioplastics is quite disappointing.
In addition to bioplastics, there is another alternative: to use carbon dioxide to make plastics. Scientists have worked hard in this field for more than ten years, and now they finally see the light of hope.
Making plastics with carbon dioxide
Scientists pointed out that instead of using fossil fuels as raw materials for plastics, we might as well do the opposite, using some chemical techniques to make plastics from waste carbon dioxide, which will revolutionize the entire petrochemical industry. Most of the carbon dioxide currently comes from hydrogen production, but researchers are still trying to capture carbon dioxide in industrial waste gas. This approach can not only reduce the use of fossil fuels, but also have an impact on climate change and reduce greenhouse gas emissions.
The key to using carbon dioxide to produce plastics lies in the design of catalysts, such as compounds containing metals such as copper. Scientists have discovered that there is a catalyst that allows carbon dioxide and epoxide to react to form a class of substances called "polyether polycarbonate polyols", which are the basis for the production of polyurethanes, which are often used to make beds Mats, cushions and refrigerator insulation.
Making mattresses with gas
A German company is producing a special mattress called Cardyon, where 20% of the material is made of carbon dioxide. Considering that the current annual production of polyurethane in the world exceeds 15 million tons, if the raw materials are replaced with carbon dioxide, it will inevitably have a huge impact.
British company Econic is also using carbon dioxide to produce polyurethane, hoping to launch foam, paint, sealant and elastic fiber products within two years. The quality of these materials is not only comparable to traditional plastics, but even better than traditional plastics in some respects. Econic pointed out that some of the materials they produce have better performance, such as fire resistance and scratch resistance.
The company estimates that if 30% of the polyol is made of carbon dioxide, it can reduce 90 million tons of carbon dioxide emissions, which is equivalent to a variety of 4 million trees, or a reduction of 2 million cars. In addition, due to the low price of carbon dioxide (about 100 US dollars per ton, compared to the standard raw material propylene oxide price of about 2000 US dollars per ton), for a factory with an annual output of 50 metric tons, annual savings of 1,000 Ten thousand U.S. dollars.
Scientists even have a bigger "ambition": use carbon dioxide to produce ethylene. At present, about half of the plastics produced in the world are made of ethylene, so ethylene is one of the most important industrial raw materials in the world. Researchers are developing a copper-containing catalyst that allows carbon dioxide and water to produce ethylene when energized.
Perhaps it will be another 20 years before polyethylene plastics made from carbon dioxide can reach commercial scale, but after 30 to 40 years, we can no longer produce ethylene from fossil fuels, so we have no choice, Other methods must be sought.
British scientists have invented a method to combine carbon dioxide with sugars such as xylose to produce polycarbonate (which can be used to produce recyclable containers such as baby bottles). The current polycarbonate production process generally uses phosgene (a highly toxic gas used as a chemical weapon in World War I) and a chemical called bisphenol A. Bisphenol A has estrogen-like properties and has been banned for baby products in Canada and other countries. If polycarbonate is produced on the basis of carbohydrates, its production and use safety will be greatly improved, making it more suitable for the production of medical implants, sutures, and organ scaffolds.
American scientists have also invented a new technology that uses electrocatalysts containing nickel and phosphorus to combine water and carbon dioxide under the action of electric current to produce complex carbon-containing molecules that can be used to produce plastics and pharmaceutical products. The researchers said that the essence of this process is equivalent to artificial photosynthesis and can be more efficient than natural photosynthesis.
Traditional plastic production methods may be the current norm, but they are not ideal. The production of single-molecule substances from fossil fuels consumes energy and pollutes the environment. Because the chemical reaction driven by thermal energy is slow, energy-consuming, and inefficient, we must find another way to find a better solution. (leaf)
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