Environmentalists all over the world have often vocalized the threats and challenges related to plastic waste management over decades. Now, these concerns have been given a ray of hope by the research done at Cornell University, New York. This study aims to ease the process of chemical recycling by turning the plastic waste back into the natural products it was manufactured from.
Plastics constitute a wide range of synthetic or semi-synthetic materials which incorporate polymers as a key ingredient. They are organic (carbon-based) products that are light, cheap, durable, and flexible. However, used plastic waste takes a considerable amount of time to decompose. The everyday use of plastic bags takes 10-20 years to decompose, plastic bottles take around 450 years and plastic items in landfills take around 1000 years to decompose. Today, about 300 million tons of plastic waste is produced every year, which is roughly equivalent to the weight of the entire human population. As, a result, huge amounts of plastic waste are accumulated in the Earth's environment, creating plastic pollution. This plastic pollution can affect land, waterways, and oceans and prove to be harmful to wildlife, their habitat, and human beings. It is also suggested by researchers that by 2050, there will be more plastic in the ocean than fish (by weight). In the ocean, marine animals are hugely impacted due to plastic waste. They suffer from mechanical effects, like entanglement in the plastic waste, problems because of ingestion of the plastic, or issues due to exposure to the chemicals released by the plastic waste. It also affects human beings and other animals through direct or indirect consumption.
Efforts have been put in recycling plastic waste for decades. According to the United States recycling statistics, around 2 million tons of plastic waste was recycled by the US in 2018, which is only 12.2% of the total plastic waste generated by them. Only 9% of the total plastic waste produced by the world has been recycled by now. 12% of the plastic waste has been incinerated while the remaining 79% lies accumulated in dumps, landfills, or the natural environment. Fortunately, researchers at Cornell University have found a way to clean up all this mess.
Researchers at the College of Engineering, Cornell University have published a study that aims to ease the process of chemical recycling. Chemical recycling is the process of turning waste products into natural resources by breaking it down physically into the smaller molecules it was originally produced from. It is a growing industry and has wide applications, including plastic waste management. The paper “Consequential Life Cycle Assessment and Optimization of High-Density Polythene Plastic Waste Chemical Recycling” was published in the journal ACS Sustainable Chemistry & Engineering on September 13th 2021. Fengqi You, the Roxanne E. and Michael J. Zak Professor in Energy Systems Engineering and doctoral student Xiang Zhao gave the details in the paper, with a framework including mathematical models and methodologies that factors a range of things including chemical recycling equipment, process, energy sources, effects on the environment and the market for finished products. The framework given in the paper is the first comprehensive analysis of its kind. It quantifies the life-cycle environmental effects of the chemical recycling of plastic waste such as human toxicity and climate change.
Researchers like Fengqi You, are helping to propagate the idea and benefits of chemical recycling among the waste industry and are also paving the way for the future of this emerging industry. The process of chemical recycling creates a ‘circular economy, i.e., the waste product is transformed completely into a natural resource. It also paves the way for recycling plastics such as high-density polyethene, used to make products like rigid bottles, toys, underground pipes and mail package envelopes, more commonly. The paper talks about the benefits of consequential life-cycle optimization as opposed to the traditional analytical tools. In a scenario designed to minimize environmental effects and maximize economic outputs, the process of life-cycle optimization produced more than 14% reduction in the emission of greenhouse gases, and more than 60% decrease in photochemical air pollution as opposed to the attributional life-cycle assessment approach used typically in environmental assessment studies.
The paper also gives a plethora of choices and variables in the technological part of the process. For example – in market conditions where there is strong demand for basic products like ethylene or propylene, the framework recommends a particular kind of chemical separation technology; whereas in market conditions demanding butane or isobutane, another kind of technology is advised. The outcome of the chemical recycling process on the environment is based on the variables like the process for supplying the chemical feedstocks and products. For example – according to the framework, onsite production of butene produces a 20% reduction in photochemical air pollution from recycling plants compared to having it supplied; whereas onsite use of natural gas causes an increase in the potentially harmful ionizing radiation by almost 37%.
“It’s a chemical process and there are so many possibilities,” Fengqi You said. “If we want to invest in chemical recycling, what technology would we use? That depends on the composition of our waste, the variants of polyethene plastic, and it depends on current market prices for end products like fuels and hydrocarbons.” “There’s always something we can twist and adjust in the technology and process, and that’s the tricky part”, he added. He also said that with the introduction of new chemical recycling techniques and changes in markets, life-cycle optimization will still be a powerful guiding tool for the emerging industry.
This revolutionary study was supported partly by the National Science Foundation. This study opens doors to new and efficient possibilities in the field of chemical recycling and also facilitates the effective management of plastic waste. Such researches and discoveries prove to be a boon to the degrading environment of the planet.
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