As millions of tons of diaper wastes accumulate in landfills, scientists developed a recycling technique to convert diaper polymers into usable adhesive. Researchers at University of Michigan worked with Procter & Gamble devised a chemical recycling process to unravel the matrix of polymer polyacrylic acid making up the superabsorbent materials of diapers.
Chemical recycling was deemed as the more efficient method since the diaper materials consist of a long chain of repeating polymer units. According to the researchers, chemical recycling aims to combine chemical transformations and chemistry to produce a valuable material. They also added that although they worked on clean diapers, cleanliness in recycling discarded diapers is assured as the chemical processes also aim to kill any bacteria present in used diapers.
Overview of the Method Used to Convert the Diaper Polymers into Adhesives/h3>
One of the authors, Takunda Chazovachii PhD, said that the superabsorbent polymers were created in ways that will enable the diaper materials to permanently retain water and withstand degradation. However, it makes the superabsorbent polymer much harder to recycle by way of mechanical recycling processes. As an alternative, they devised a chemical recycling process to convert the superabsorbent polymers into adhesives, since both materials are extracted from acrylic acid.
Study author Anne McNeil stated that the polymers found in diaper materials can be compared to a loosely woven fishing net repeatedly bound together to make them superabsorbent. What they needed to discover is a way to untangle the polymers into water soluble chains. Fellow researchers Chazovachii figured out that in order to break the crosslinks, the polymers should be heated with base or acid present.
Additionally, they also needed to determine whether the chemical recycling process can be carried out on an industrial scale. Study collaborators Jose Alfaro and Madeline Somers performed a life cycle assessment and were able to determine that chemical recycling would use 10 times less energy. Moreover, their life cycle study showed that the acid-based method would have carbon dioxide emissions that is 10 times lower in terms of global warming impact.