Are biodegradable plastics the terminator of white pollution? It looks difficult at the moment
In the 19th century, the American printer Hayt repeatedly experimented after seeing the reward for finding a substitute for ivory, and found that the substance obtained by adding camphor to nitrocellulose was hard but not brittle, and could be molded into various shapes at will. He named this material "Celluloid Nitrate", which is the earliest synthetic plastic in human history. In 1907, the American chemist Baekeland realized the artificial synthesis of polymer phenolic resin, which opened the prelude to the application of synthetic polymer plastic materials by mankind. The term plastic is derived from the Greek word "plastikos", which means a substance molded into any shape.
In the past half century, the output of plastics has increased by more than 20 times. They are lightweight and durable, with low cost and diverse functions, and become a ubiquitous product. Plastic footprints are found in every corner of the world, including the deepest part of the seabed, the highest peak of Mount Everest, and the polar ice caps.
Plastics are hard to degrade and harm the environment. Is it possible to change the material formula so that it will eventually degrade under certain environmental conditions after it is discarded? Biodegradable plastics are therefore highly sought after and high hopes are placed. But can biodegradable plastics cure plastic pollution?
Xu Zhonghua, vice president of R&D Asia of French Total Group and Chief Scientific Representative of Total China, believes that the large-scale promotion of bio-based degradable plastics is currently unrealistic. In an interview with The Paper, he said that for a long time, we still have to rely on traditional plastic products.
"The major prerequisite for the promotion of the use of bio-based plastics is to give priority to food security. In addition to the question of where the raw materials come from, the cost of bio-based degradable plastics is still higher than that of ordinary plastics. The technology of bio-based degradable plastics is continuing At the same time of innovation, we should strengthen the recycling and reuse of traditional plastics, give full play to their value, and gradually move towards an environment-friendly sustainable development path." Xu Zhonghua said.
Biodegradable plastic, the terminator of plastic pollution?
Where does plastic waste come from? The straws and packaging bags for online ordering, the tape and cushions in the express box, and the solid plastic particles in the shower gel are all produced in large quantities all the time. The global spread of the new crown epidemic has spawned a sudden increase in the demand for plastics. Disposable masks, protective clothing, gloves, and outer packaging of popular disinfection products are everywhere.
Most fossil-based plastics cannot be degraded, which means they may exist in nature for hundreds or even thousands of years. Beginning in the 1980s, scientists began to study whether plastic can be degraded and disappeared through the action of microorganisms in an environment where microorganisms are active. Polylactic acid (PLA) products derived from crops such as corn are currently the most successful bio-based degradable plastics. As it is a fully bio-based material, PLA is completely recyclable and biodegradable. It can be recycled mechanically or chemically, or in some cases, used as fertilizer through composting.
In addition to the well-known identity of the multinational oil and gas giant, Total has entered the field of degradable bio-based materials and biofuels very early. In 2007, Total and Galactic established a joint venture Futerro in Belgium to explore the use of renewable plant resources to produce PLA bioplastics. In 2018, Total and its Dutch partner Corbion launched a PLA plant in Thailand to produce bio-based polymers using non-GMO sugar cane as raw materials. The plant has an annual production capacity of 75,000 tons, making it the second largest PLA plant in the world.
Total's PLA plant in Thailand uses non-GMO sugarcane as raw material to produce bio-based polymers. Photo courtesy of Total
According to Xu Zhonghua, there are several development directions for degradable plastics: In addition to PLA that can completely decompose to produce carbon dioxide and water under certain conditions, there are also destructive biodegradable plastics that promote degradation through additives, and polymers that are traditional plastics. Add light-sensitive photoinitiator and other additives to the light-degradable plastic in the chain.
With the rise of the global plastic reduction movement, the emergence of “biodegradable plastics” on the market has been mistaken for “saviors” by many people. People seem to feel comfortable when they discard this plastic because they imagine that these plastics will eventually become Degradation in the environment will not cause harm. But it is worth noting that degradable plastics also need to be recycled, properly disposed of in a specific way, and should not be discarded at will.
One of the reasons why the plastic dilemma is difficult to solve is that people's requirements for materials are changing during the entire life cycle of a plastic product. "During use, the strength, temperature resistance, and moisture resistance of plastics must meet certain conditions. Even degradable plastics must be decomposed under the combined action of specific temperature, humidity and microorganisms after being discarded. It will “disappear” in the natural environment, otherwise it cannot be used at room temperature."
Biodegradable plastics are not a panacea. Xu Zhonghua said that at the beginning of the establishment of Total's PLA plant in Belgium, it also encountered many difficulties in product promotion. Even now, the entire biodegradable plastics industry still faces a series of common challenges. For example, the cost is higher than that of ordinary plastics, and the scope of application of bio-based materials has been narrowed.
But the more restrictive condition is that it cannot compete with food for resources. "Whether it is using bio-plastics or lubricating oil, the biggest challenge is where the raw materials come from. First of all, we cannot compete with traditional food crops for land resources. Under this basic premise, we should be as close as possible to provide a certain scale and cost of raw materials. Thailand is a very good choice for a low, long-term guaranteed supply of raw materials. "Total's PLA plant in Thailand is currently launching polylactic acid materials for different industries, which are used in food packaging, automotive interiors, etc. In general, PLA materials are more suitable for areas with higher food safety requirements, such as tea bags and capsule coffee.
Total PLA plant in Belgium, photo courtesy of Total
Based on the above reasons, Xu Zhonghua believes that there is still a development process for large-scale applications of bio-based degradable plastics. If all bio-based degradable plastics are adopted in the world today, it will have a great impact on food supply.
"At the current stage, it is more suitable for specific fields related to food and medical care. Perhaps in the future we can develop carbon dioxide-based plastics and finally decompose them into gases. But before further technological breakthroughs, we must completely rely on degradable plastics, and Quite a long way to go."
Plastic recycling under the ban is not only a matter for manufacturers
China is the world's largest producer and consumer of plastics. In 2019, China produced 63 million tons of waste plastics and recycled 18.9 million tons. From the "foreign garbage" ban to the new version of the "plastic restriction", China's plastic pollution control system has continued to upgrade in recent years.
In 2007, China officially issued the "plastic restriction order" for the first time. The core is to prohibit the production, sale, and use of ultra-thin plastic shopping bags nationwide from June of the following year, and to implement a paid use system for plastic shopping bags. The plastic restriction order has been implemented for more than ten years, and the effect of its implementation is quite controversial. But it is undeniable that with the rapid rise of e-commerce, express delivery and takeaway industries, disposable plastic packaging materials have switched the main battlefield, and consumption has not decreased but increased.
In 2019, an average of 7.08 million express shipments per hour were sent to the whole country. According to statistics from environmental protection agencies, the domestic express delivery industry consumed more than 39.8 billion meters of tape in 2018. These plastic tapes can wrap the earth nearly 1,000 times. In 2015, this number was only 425 times. 99% of express delivery waste plastic will be mixed into domestic waste and eventually burned or landfilled.
The upgraded version of the "Plastic Restriction Order" jointly issued by the National Development and Reform Commission and the Ministry of Ecology and Environment at the beginning of this year has set a clear timetable, and the policy measures for plastic reduction and recycling will be implemented throughout the production, circulation, use, recycling, and disposal of plastic products. All links.
"Plastic is a friend of mankind, not an enemy. It provides a lot of support and convenience for the development and progress of human society." Xu Zhonghua said that under the plastic restriction order, to achieve efficient plastic recycling, the most important thing is everyone's participation. The treatment of waste plastics is not only the business of manufacturers and scientists, but also the business of plastic users. The public's good garbage classification can greatly reduce the challenges of plastic recycling.
In February 2019, Total acquired Synova, a French plastic recycling company. Combine polymer expertise with Synova's recycling expertise to increase the supply of recycled polypropylene that can be used in automotive applications. Synova can produce 20,000 tons of polypropylene annually from recycled plastic.
Another important significance of plastic limit is to save the ocean. Every year, more than 8 million tons of plastic waste flows into the ocean around the world.
Plastic waste is discarded directly or from land through rivers, wind and eventually into the ocean.
According to the Bulletin of the State of China’s Marine Ecological Environment in 2019 by the Ministry of Ecology and Environment, the monitoring of marine debris in 49 regions across the country and the monitoring of marine microplastics at 15 points along the coast of the Bohai Sea and the East China Sea revealed that floating debris, Plastic garbage accounted for 84.1% and 81.7% of beach garbage, respectively; plastic garbage in the seabed was the largest, accounting for 92.6%, mainly fishing ropes, plastic ropes, plastic fragments and plastic bags.
In addition, the density of floating microplastics on the sea surface of the Bohai Sea and the East China Sea is 0.82 pieces/m3 and 0.25 pieces/m3 respectively. They are mainly threads, fibers and fragments. The main components are polyethylene, polyethylene terephthalate and Polypropylene. Microplastics refer to countless tiny fragments and particles formed by the decomposition of plastic garbage in seawater, and also include plastic microbeads added in daily chemical products.
Globally, according to the "Atlas of the Seas" published by the German Heinrich Behr Foundation, only 20% of the plastic waste in the ocean comes from the sea (mainly ships), and the remaining 80% comes from the land. Floating plastic clusters larger than some countries have formed in the Pacific and Atlantic.
"The governance of marine plastics is a global difficulty. For large marine plastics, the current common method is still salvage, but the salvage process will produce new pollution. Pollution that is invisible to the naked eye is more deadly. Marine microplastics adsorb heavy metals or other organic materials. After pollutants, they may be transmitted to the human body along the food chain." Xu Zhonghua appealed that marine microplastic pollution is like a new crown virus in a sense. It drifts with ocean currents and occurs somewhere, but the harm will not only stay In one place, there is a global crisis. "Marine microplastics governance requires global cooperation."
According to reports, Total is one of the founding members of the Plastic Waste Elimination Alliance, which has nearly 30 industry members covering all links of the plastic value chain. The alliance has pledged to invest 1.5 billion US dollars to develop solutions that can reduce plastic pollution in the environment, especially in the ocean.
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