New invention recycles cotton waste into new high-value fabrics

Swedish researchers have invented a method to convert waste cotton fabric into sugar, which can be used to make spandex, nylon or ethanol.

Light industry has been trying for decades to recycle used textiles, but the material is really hard to recycle and often ends up in landfills.

Experiment to convert cotton fabric into glucose. (Photo from Lund University)

To save this huge common material, scientists from Lund University in Sweden have invented a method to convert cotton into sugar, which in turn turns into high-value products such as spandex, nylon and ethanol.

About 25 million tons of cotton textiles are discarded around the world each year. When the different fabrics are added together, a total of more than 100 million tons of textiles and garments each year end up as waste. In Sweden, most of the textile waste goes directly to the incinerator to heat the county population. In other countries, textile waste has a worse fate, old clothes are often buried in landfills.

Some fabrics, with fibers that are so strong that they can be reused, are being made today and can be made many times, said Dr Edvin Ruth, a chemical engineering researcher at Lund University. more in the future. But a lot of fabrics go to waste because there are fibers that are too short to be reused, and more and more all cotton fibers are becoming too short for the regeneration process.

Dr. Edvin Ruth working at the Department of Chemical Engineering in Lund, accumulated a great deal of knowledge about the use of microorganisms and enzymes, various additives and catalysts to convert these carbohydrates' stable' in biomass into simpler molecules. Everything from bio-waste and black wine to straw and wood chips can become bio-alcohol, biogas and chemicals.

In research led by Dr. Edvin Ruth, a team of scientists successfully breaks down the plant fibers in cotton and cellulose fibers into smaller components. But no microorganisms or enzymes are involved in this process. This transformation involves soaking the waste cloth in sulfuric acid and obtaining a clear, dark amber sugar solution.

Lund University scientists have demonstrated a process to convert cotton fabric into sugar water to produce new fabric or ethanol. (Lund University Video).

Dr Ruuth, who adapted the 'recipe' for the degradation of cotton fibers with PhD students Dr Miguel Sanchis-Sebastiá and Professor Ola Wallberg explains: 'The key condition is to find the right combination of temperature and concentration. sulfuric acid'.

The team's plan is to produce chemicals, which can be used as raw materials for many other textiles such as spandex and nylon, or to produce ethanol.

According to Ruth, glucose is a very versatile molecule with many potential uses for ethanol production. From an ordinary cloth, the team extracted 5 liters of sugar solution, each liter containing the equivalent of 33 glucose tablets. But it is not possible to turn the liquid into fresh water because it also contains toxic sulfuric acid.

One of the challenges is overcoming the complex structure of cellulose cotton. The uniqueness of cotton is that cellulose has a high degree of crystallinity. This property makes it difficult to break down chemicals and reuse the resulting components. In addition, there are many surface treatments such as dyes and other contaminants that must be removed. More than that, structurally, a cotton scarf and an old pair of jeans are very different.

Technology is a very sophisticated process to find the right acid concentration, the right number of treatment stages and the right temperature. The idea of ​​hydrogenation of pure cotton was discovered in the 1800s. The main difficulty was to make the process efficient, economically viable and not polluting the environment.

The team started testing glucose extracts from litchi a year ago, with a very small starting point of 3-4%. Currently the research team reached 90%. Once the decomposition formula is perfected, the technique will be very simple and cheap to apply.

The new invention of the Lund University research team opens a new direction, considering textile waste as a raw material source for the recycling process into valuable chemical components to produce raw materials for all kinds of products. synthetic garment materials or ethanol, reimburse a part of the economic value lost when used fabrics or cotton products are buried in landfills.