A novel chemical recycling approach disassembles polyester and spandex into useful monomers, while preserving cotton and nylon for potential reuse. This method may enhance textile waste recycling by reducing the necessity for sorting and separation procedures.

Source: ChemistryWorld

Approximately 100 billion clothing items are sold annually, with the rise of 'fast fashion' since the early 2000s contributing to increased textile production. However, the production and short lifespan of inexpensive garments have significant environmental consequences.

Andini and her team in the U.S. have demonstrated a rapid and straightforward chemical recycling technique that can be applied to common components in mixed textiles. Using microwave-assisted glycolysis with a zinc oxide catalyst, they can separate polyester, cotton, nylon, and spandex in mixed waste streams.

Initially, the researchers applied the catalytic conditions to pure samples of polyester and cotton, the most prevalent fibers in the market. Polyester broke down into monomers, with 90% converting into bis(2-hydroxyethyl) terephthalate (BHET), a valuable material for yarns, resins, and filaments. Cotton experienced an 8% mass loss but remained largely intact. They then tested the method on T-shirts composed of a 50:50 blend of polyester and cotton, achieving complete depolymerization of polyester at temperatures above 210°C in under 15 minutes.

Given the diverse nature of actual textile waste with various additives and impurities, the team examined the process on textiles with different dyes and finishes. This led to a decreased BHET yield, indicating that additives might impede the zinc oxide catalyst's effectiveness.

The researchers also investigated blends with other common textile fibers. Treating a 90% nylon/10% spandex blend left nylon unchanged while breaking down spandex into monomers, including 4,4′-methylenedianiline, a crucial element in polyurethane foam and fiberglass plastics.

When the method was applied to mixtures containing polyester, cotton, spandex, and nylon, the team succeeded in depolymerizing polyester and spandex while keeping cotton and nylon intact.