Japan – As recently proved by experts from the Tokyo Institute of Technology, bioplastics may be chemically regenerated into nitrogen-rich fertilizers in an easy and environmentally acceptable manner.
Their discoveries pave the path for long-term circular systems that address concerns including plastic pollution, petrochemical resource depletion, and global famine.
Over the last century, plastics have taken the globe by storm, with applications in almost every facet of our lives. However, the emergence of these synthetic polymers, which serve as the foundation for plastics, has contributed to a slew of major environmental problems. The most serious of these are the excessive usage of petrochemical compounds and the dumping of non-biodegradable materials without recycling; just 14% of all plastic garbage is recycled, which barely makes a dent in the problem.
To overcome the plastic problem, we must create “circular” systems in which the raw materials used to make plastics are returned to the source after disposal and recycling. A team of scientists lead by Assistant Professor Daisuke Aoki and Professor Hideyuki Otsuka at Tokyo Institute of Technology is pioneering a revolutionary concept. Plastics made from biomass (bioplastics) are chemically regenerated back into fertilizers in their new environmentally friendly process. This discovery will be published in Green Chemistry, a Royal Society of Chemistry magazine devoted to breakthrough research on sustainable and eco-friendly technology.
Focus on PIC
The researchers concentrated on poly (isosorbide carbonate), or “PIC,” a bio-based polycarbonate that has received a lot of attention as an alternative to petroleum-based polycarbonates. As a monomer, PIC is made from isosorbide (ISB), a non-toxic substance obtained from glucose. The carbonate connections that connect the ISB units can be disrupted by ammonia (NH3) in a process known as ‘ammonolysis.’ The method yields urea, a nitrogen-rich chemical commonly used as a fertilizer. While this chemical reaction was not a surprise to scientists, few studies on polymer degradation have concentrated on the possible applications of all degradation products rather than just the monomers.
First, the researchers looked at how well complete ammonolysis of PIC could be performed in water under mild conditions (30°C and atmospheric pressure). This decision was made to avoid the usage of organic solvents and unnecessary amounts of energy. The researchers meticulously examined all of the reaction products using nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and gel permeation chromatography.
Despite the fact that they were able to manufacture urea in this manner, the decomposition of PIC was not complete even after 24 hours, with several ISB derivatives still present. As a result, the researchers increased the temperature and discovered that complete degradation could be accomplished in roughly six hours at 90°C! Dr. Aoki emphasizes the advantages of this approach “The reaction happens without the use of a catalyst, suggesting that ammonolysis of PIC may be simply accomplished using aqueous ammonia and heating. As a result, this technique is both operationally straightforward and environmentally friendly in terms of chemical recycling.”
Viability of fertilizer-from-plastics systems
Finally, the scientists conducted plant growth studies with Arabidopsis thaliana, a model organism, to demonstrate that all PIC breakdown products can be used directly as fertilizer. Plants treated with all PIC degradation products grew better than plants treated only with urea.
This study’s overall findings demonstrate the viability of building fertilizer-from-plastics systems. The systems can not only assist combat pollution and resource depletion, but they can also help fulfill the world’s rising food demand. Dr. Aoki ends on a positive note: “We are certain that our study will pave the way for the development of sustainable and recyclable polymer materials in the near future. The era of “bread from plastics” is rapidly approaching!”