Oxidative method for decolorizing textile materials
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Solution Overview
Problem
Current recycling methods for synthetic fiber textiles are hindered by the presence of colorants, which require costly and complex depolymerization and repolymerization steps, and existing wastewater treatment processes are not efficient in selectively removing colorants from polymer materials without degrading the polymers.
Innovation Solution
A method using a Fenton's reagent, comprising hydrogen peroxide and an iron catalyst, combined with a ketone such as acetone, to decolorize synthetic polymer materials like polyester textiles without significant degradation, by treating them at a pH of 4 or less and temperatures above 50°C, effectively removing colorants while preserving the polymer structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If depolymerization and repolymerization steps are used to remove colorants, then colorant removal is achieved, but process cost and complexity increase significantly
Solution Approach 1:
The patent extracts and removes only the colorant component from the polymer material using selective chemical treatment, while leaving the polymer structure intact. This avoids the need for complete depolymerization and repolymerization, thereby simplifying the process while achieving colorant removal.
Solution Approach 2:
The patent employs parameter changes by adjusting pH levels and using specific chemical reagents to selectively target and remove colorants without affecting the polymer. This selective approach based on chemical parameter manipulation eliminates the need for complex depolymerization- repolymerization cycles.
2Object-generated harmful factors
If conventional wastewater treatment processes are used to remove colorants, then colorant removal is attempted, but polymer degradation occurs
Solution Approach 1:
The patent applies local quality by using selective chemical treatment that targets only the colorant molecules with specific chemical properties, while the polymer material remains unaffected. This localized chemical action ensures colorant removal without compromising polymer structure stability.
Solution Approach 2:
The patent introduces chemical intermediaries (specific reagents and pH conditions) that facilitate selective colorant removal. These intermediaries interact preferentially with colorants rather than the polymer, enabling colorant extraction while preserving polymer integrity.
3Productivity
If colorants are present in recycled synthetic fibers, then recycling can proceed, but commercial attractiveness is reduced
Solution Approach 1:
The patent performs preliminary colorant removal treatment on recycled synthetic fibers before they enter the main recycling process. This preliminary decolorization step enhances the commercial value of recycled materials, making them more attractive for manufacturing applications while maintaining recycling efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves significant decolorization of synthetic polymers with minimal impact on their structure, allowing for the recycling and reuse of textiles, as evidenced by reduced K/S values and minimal changes in intrinsic viscosity and molecular weight.
Implementation Method 1
treating a dye-colored synthetic polymer with a treatment composition, the treatment composition comprising (a) hydrogen peroxide, (b) an iron-containing catalyst
Implementation Method 2
oxidative method for decolorizing textile materials
Implementation Method 3
the treating is carried out at a temperature of at least 50° C.
Implementation Method 4
an iron-containing catalyst
Data Source
AI summary
The disclosure relates to a method for decolorization of a dye-colored synthetic polymer, which includes the steps of treating a dye-colored synthetic polymer, such as polyester, with a treatment composition at pH 4 or less, the treatment composition comprising hydrogen peroxide, an iron catalyst, water, and a ketone. The resulting decolorized synthetic polymer is then separated from the treatment composition.