Recycling is easy to advocate, it is harder to do. In theory, paper, plastics, glass and metals can all be recycled but in practice, well that’s a different story. Aluminum, for example, is readily recycled. The metal can be melted down and used to make aluminum’s properties being affected. But such is not the case for plastics. Take, for example, polyethylene terephthalate, the plastic used to make those ubiquitous water and soft drink bottles. You can recognize this plastic by the number one recycling logo printed on the bottom. Yes, PET, as the plastic is abbreviated, can be recycled, although the bottles cannot be refilled. Plastic is not as inert as glass and there is no way to know what someone may have stored in an empty plastic bottle. Maybe some cleaning agent, or gasoline that could have been absorbed by the plastic. So the bottles cannot be refilled, but they can be recycled. How? The plastic is mechanically ground up, melted, usually mixed with virgin plastic, and formed into fabrics, carpeting, packaging and plastic lumber. But not made into new bottles. The problem is that the process by which plastics are made involves the stringing together of small molecules, called monomers, into long chains known as polymers. This is accomplished by the use of catalysts that are usually metal oxides or hydroxides. A small residue of these always stays behind in the plastic and causes a problem when the plastic is melted down and reformed into a novel form. The embedded catalyst weakens the plastic so that it isn’t suitable for a bottle, although it is fine for other uses.
A more attractive idea would be to break the plastic down into its original monomer components and sue these to make a polymer again. This can be done, but it requires high temperatures and pressures, which in turn make the process prohibitively expensive. The search is therefore on to fin a way to break the plastic down into its original components in a more environmentally friendly fashion. And new researchers at IBM and Stanford University may have come up with such a process. It all hinges on “organocatalysts,” an exciting area of research. Unlike most industrial catalysts, organic catalysts do not contain metal atoms and usually work under mild conditions. Plastic bottles can be chopped up, placed in a solution with the catalysts, and have their polymeric components be broken down into monomers. These monomers can be immediately reacted again with organic catalysts to form new polymers. If the process can be made to work on a large scale, it would go a long way towards making the recycling of bottles efficient and economic. Of course all of this is contingent on people placing bottles in the recycling bin in the first place, which many just don’t do. Most of the 13 billion plastic bottles disposed of each year globally end up in landfills. Of course it would be bar better to cut down on the use of these bottles in the first place. A glass and a tap make a very nice environmentally friendly combo.