So far, recycling cotton means converting into other cotton products. What if we could recycle cotton into Nylon and Spandex? Is it possible? The answer is a big YES! Researchers from Sweden’s Lund University have found a way to convert cotton into sugar, which in turn can be made into spandex, nylon, or ethanol.
Edvin Ruuth is working at the Department of Chemical Engineering in Lund. There is a great deal of information about using micro-organisms and enzymes to transform the “tougher” carbohydrates in biomass into simpler molecules. This means that everything from biological waste and black liquor to straw and wood chips can become bioethanol, biogas and chemicals. In the new research, scientists have succeeded in breaking down the plant fiber in cotton, the cellulose, into smaller components. However, no micro-organisms or enzymes are involved. Instead, the process involves soaking the fabrics in sulphuric acid. The result is a clear, dark, amber-colored sugar solution.
The researchers started making glucose out of fabrics a year ago, the return was a paltry three to four per cent. Now he and his colleagues have reached as much as 90 per cent. Once the recipe formulation is complete, it will be both relatively simple and cheap to use. However, for the process to become a reality, the logistics must work. There is currently no established way of managing and sorting various textiles that are not sent to ordinary clothing donation points.
Fortunately, a recycling center unlike any other in the world is currently under construction in Malmö, where clothing is sorted automatically using a sensor. Some clothing will be donated, rags can be used in industry and textiles with sufficiently coarse fibers can become new fabrics. The rest will go to district heating.
Hopefully, the proportion of fabrics going to district heating will be significantly smaller once the technology from Lund is in place. From a normal sheet, they extract five liters of sugar solution, with each liter containing the equivalent of 33 sugar cubes. However, you couldn’t turn the liquid into a soft drink as it also contains corrosive sulphuric acid.
Ruuth said, “What makes cotton unique is that its cellulose has a high crystallinity. This makes it difficult to break down the chemicals and reuse their components. In addition, there are a lot of surface treatment substances, dyes and other pollutants which must be removed. And structurally, a terrycloth towel and an old pair of jeans are very different. Thus it is a very delicate process to find the right concentration of acid, the right number of treatment stages and temperature.”
