Most clothing is blended. A typical garment mixes cotton and polyester fibers so intimately that mechanical separation is impossible — the fibers are spun together, woven together, sometimes fused at the yarn level. Textile recycling has treated this as a separation problem, searching for ways to sort one fiber from the other without destroying either. The problem has resisted solution for decades. About 92 million tonnes of textile waste enters landfills each year.
Researchers at the University of Amsterdam and Avantium (Nature Communications, 2025) dissolved the problem by dissolving one component. They soaked polycotton blends in 43% hydrochloric acid at room temperature for one to four days. The acid hydrolyzed every glycosidic bond in the cellulose, converting the cotton into glucose — a water-soluble sugar that washes away. The polyester remained intact, its ester bonds resistant to acid hydrolysis under these conditions. No heating. No pressure. No enzymes or catalysts. The cotton dissolved; the polyester survived.
The recovery rates were high: 75% of the cotton was recovered as glucose, and 78% of the polyester was recovered as clean fiber suitable for reprocessing. The glucose can serve as feedstock for biobased chemicals. The polyester can re-enter existing recycling streams. Pilot-scale trials at Avantium's Dawn plant confirmed scalability.
The structural observation: the separation was always chemically available. Cellulose and polyester have fundamentally different bond chemistries — glycosidic linkages versus ester linkages — and their vulnerability to acid hydrolysis differs by orders of magnitude. The reagent that exploits this difference, hydrochloric acid, is among the oldest and cheapest industrial chemicals. No novel chemistry was required. The solution was to stop framing the problem as separation and start framing it as selective destruction. You do not need to pull the fibers apart. You need to find a chemical environment where one fiber cannot survive and the other can. The environment existed all along. What changed was the question.