# Adsorptive Decolorization of a Disodium Terephthalate Solution from Monomer Recycling of Polyester

## TL;DR

This paper explores using activated carbon to remove color from recycled polyester solutions, improving the quality of recycled materials for a circular economy.

## Contribution

The study identifies optimal conditions for decolorization using activated carbon, enabling high-quality polyester recycling.

## Key findings

- Activated carbon effectively decolorizes disodium terephthalate solutions under neutral pH and 80 °C.
- The process meets industrial color specifications for recycled terephthalic acid.

## Abstract

The global economy is increasingly faced with the challenge of accepting its responsibility for recycling polyester textile waste. With back-to-monomer recycling technologies, PET can be recycled to its monomers, terephthalic acid and ethylene glycol. The recycling of polyester-containing textiles requires the complete separation of all contaminating materials, dyes, and additives, which can only be achieved by depolymerization technologies. This article presents the adsorptive decolorization of a disodium terephthalate solution from the alkaline hydrolysis of polyester textile waste. The influence of different adsorbents, temperature (30–80 °C), and pH value (7–12) on the adsorptive decolorization process is investigated. As a result, activated carbons for decolorization have been identified. It was found that the adsorption process is favorable at neutral pH and a temperature of 80 °C. The findings show that a color value within the industrial specification can be obtained for recycled terephthalic acid using activated carbon adsorption. This adds a key step for high-quality textile-to-textile recycling and thus contributes to a circular economy for polyester.