Science & Technology

Convert bio-based polymers to fertilizer

Figure 1. Using PIC degradation products as nitrogen-rich fertilizers closes sustainable loops, making bioplastics a much more attractive option to address the environmental problems posed by traditional petroleum-based plastics. Become.Credit: Tokyo Institute of Technology Daisuke Aoki

Plastics have swept the world for the past century and have been applied to almost every aspect of our lives. However, the rise of these synthetic polymers, which form the basis of plastics, contributes to many serious environmental problems. The worst of these is the disposal of non-biodegradable materials without overuse and recycling of petrochemical compounds. Only 14% of plastic waste is recycled, which rarely causes problems.

To solve the plastic conundrum, it is necessary to develop a “circulation” system that goes around completely after the raw materials used to make plastic are discarded and recycled. At Tokyo Institute of Technology, a team of scientists led by Assistant Professor Daisuke Aoki and Professor Hideyuki Otsuka is pioneering a novel concept. In a new eco-friendly process, the plastics (bioplastics) made from biomass are chemically recycled and returned to fertilizer. This study will be published on October 28, 2021. Green chemistry, A journal of the Royal Society of Chemistry, which focuses on innovative research on sustainable and environmentally friendly technologies.

The team focused on poly (isosorbide carbonate), a type of bio-based polycarbonate that has received a lot of attention as an alternative to petroleum-based polycarbonate, or “PIC”. PIC is manufactured using a non-toxic substance derived from glucose called isosorbide (ISB) as a monomer. The interesting part is that the carbonate link that binds to the ISB unit can be cleaved using ammonia (NH).3) In a process known as “am monolysis”. This process produces urea, a nitrogen-rich molecule that is widely used as fertilizer. Although this chemical reaction was not a secret of science, few studies on polymer degradation focused on the potential uses of all degradation products, not just monomers.

First, scientists investigated how well a complete amponology of PIC can be performed in water under mild conditions (30 ° C and atmospheric pressure). The rationale behind this decision was to avoid the use of organic solvents and excessive amounts of energy. The team carefully analyzed all reaction products through a variety of means, including nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and gel permeation chromatography.

They were able to produce urea in this way, but the degradation of PIC was not completed even after 24 hours and many ISB derivatives were still present. Therefore, when the researchers raised the temperature, they found that it could be completely decomposed at 90 ° C in about 6 hours. Dr. Aoki emphasizes the benefits of this approach. “The reaction takes place without a catalyst and shows that the ammonia decomposition of the PIC can be easily carried out using aqueous ammonia and heating. Therefore, this procedure is easy to operate and environmentally friendly from the viewpoint of chemical recycling. is.”

Finally, as a proof of concept that all PIC degradation products can be used directly as fertilizers, the team Arabidopsis, Model organisms. They found that plants treated with all PIC degradation products grow better than plants treated with urea alone.

The overall results of this study show the feasibility of developing a fertilizer system from plastic (Figure 1). Not only does this system help combat pollution and resource depletion, it also helps meet the growing global food demand. Dr. Aoki said as follows. “We are confident that our work is a milestone in the development of sustainable and recyclable polymer materials in the near future. The era of” bread from plastic “is just around the corner! “

Reference: “From Plastic to Fertilizer: Chemical Recycling of Bio-based Polycarbonate as a Fertilizer Source” October 28, 2021 Green chemistry..
DOI: 10.1039 / D1GC02327F

Convert bio-based polymers to fertilizer Convert bio-based polymers to fertilizer

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