How to recycle diapers into stickers

A chemical recycling process devised by researchers from the University of Michigan allows to reduce the polluting impact of diapers and to save energy even in the production of adhesives

(photo: Pixabay) the importance of recycling is increasingly topical. One of the big problems is that of disposable diapers and sanitary napkins, which today are difficult to recycle. The polymers they are made of, in fact, are specially designed to retain liquids permanently and to be resistant and long-lasting. But now a team from the University of Michigan has developed a new system that could change things: thanks to a chemical recycling process, diapers could find new life in the form of adhesives, to the benefit of the planet. Here's how.

Chemical recycling

The intention of the researchers is to transform diapers into a different product that has at least the same value, if not even higher. With mechanical recycling (which breaks up polymers different from each other in terms of composition and length of the molecules) this is not possible, while it is possible with a chemical process.

"Absorbent and adhesive polymers both derive from acrylic acid - explains Takunda Chazovachii, one of the authors of the study published in Nature Communications -. This common origin inspired our idea of ​​recycling. ”

From diapers to adhesives in three steps

The process devised by US scientists to move from a network of absorbent polymers to adhesive polymers predict three stages.

First of all it is necessary to break the network of absorbent polymers in such a way as to obtain water-soluble chains. Chazovachii and colleagues found that this step is possible by heating the material in the presence of an acidic or basic substance. Thus the cross-links are broken. A more detailed analysis, then, allowed us to understand that the use of an acid was the most convenient both from an environmental point of view (with an impact on global warming 10 times less) and from an industrial point of view (it requires 10 times less energy than approach with a base).

The second step of the process aims to shorten the polymer chains thus obtained. This time, the researchers opted for a mechanical action, through sonication with tiny air bubbles which, when exploding, break the chains while leaving the bricks that constitute them intact. If desired, in some cases, sonication can be avoided by further streamlining the recycling process, which becomes even more ecological.

Finally, to make the adhesive chains, another chemical step with a solvent must be used ( which can be reused) which converts the acid groups of polymers into ester groups. And there you have it.

Double convenience

For the proposal to really be considered for large-scale applications, the researchers had to make a list of pros and cons of the process and sum up. What emerged is that their idea can not only help reduce the environmental impact of this type of waste, but could also have an industrial advantage. By comparing the process of producing adhesives through the recycling of diapers with the traditional process that obtains them from oil, the scientists calculated a 22% reduction in the impact in terms of climate warming and 25% in energy consumption. >
However, there is still a stumbling block to overcome. For the moment the tests have been carried out on clean nappies, but the team has announced that it is collaborating with industrial partners that deal with cleaning used nappies to demonstrate the effective validity of the process.


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Topics

Chemistry Climate Waste globalData.fldTopic = "Chemistry, Climate, Waste"

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