Semidry Acid Hydrolysis of Polyester/Cotton Blends through In Situ Catalyst Loading

Polyester/cotton blends, which represent over 60% of the textile market, present a significant challenge for chemical recycling. Conventional solution acid hydrolysis suffers from high acid consumption and low solid/liquid ratios and results in severe equipment corrosion due to the acid-resistant nature of polyester. To address the limitation, we developed an in situ catalyst-loaded semidry acidic hydrolysis method for depolymerization of polyester/cotton blends. By leveraging hydrogen bonding between cotton and a phosphomolybdic acid (PMA) catalyst, the acidic catalyst is anchored onto the fabric, forming localized acid microreactors that facilitate the hydrolysis of polyester without requiring an additional aid solution. The semidry hydrolysis process cuts acid usage to 1/100 of conventional processes, increases the solid–liquid ratio by 3 times, and accelerates the reaction rate by 25 times, while achieving a TPA yield exceeding 94%. The corrosion is markedly suppressed. Both the impregnation solution and the used catalyst are recyclable, contributing to a more sustainable catalytic process. The study offers a sustainable and efficient strategy for recycling blended fabrics with a broad applicability.