Separating Cellulose from Polyester Blends via Ionic Liquid Dissolution
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Solution Overview
Problem
Current recycling strategies for cotton/polyester blends are inefficient, often degrading either the cellulose or polyester components, and lack effective methods for simultaneous upcycling of both materials, particularly due to the heterogeneity of these blends and the complexity of processing steps involved.
Innovation Solution
A method using superbase-based ionic liquids, such as DBNH OAc, to selectively dissolve cellulose from cotton/polyester blends, allowing for the separation and subsequent processing of both components without significant degradation, enabling the production of high-quality cellulose fibers and purified polyester through dry-jet wet spinning and solvent recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical separation is used for cotton/polyester blends, then the separation process is simple, but the separation is ineffective due to heterogeneity of the blend
Solution Approach 1:
The patent replaces mechanical separation methods with chemical dissolution using ionic liquids. The ionic liquid selectively dissolves cellulose from the cotton/polyester blend, allowing chemical separation instead of mechanical sorting. This substitution enables effective separation of heterogeneous blends that cannot be separated by mechanical means alone.
2Manufacturing precision
If dissolution of polyester is used, then separation can be achieved, but the process requires elevated temperatures and degrades the cellulosic component
Solution Approach 1:
Instead of dissolving polyester to separate the blend, the patent inverts the approach by selectively dissolving cellulose while leaving polyester intact. The ionic liquid is chosen to have selective affinity for cellulose, reversing the conventional dissolution strategy and preventing degradation of the cellulosic component while achieving separation.
3Manufacturing precision
If hydrolysis or glycolysis is used to degrade polyester, then polyester can be separated, but the cellulosic component is also affected and the process is complex
Solution Approach 1:
The patent extracts and removes polyester from the blend through selective dissolution of cellulose in ionic liquid, followed by filtration. This extraction approach separates polyester without requiring complex hydrolysis or glycolysis reactions, simplifying the processing steps while achieving effective separation of both components.
4Manufacturing precision
If NMMO is used to dissolve cellulose, then cellulose can be separated, but the method requires additional processing steps and depolymerization of polyester first
Solution Approach 1:
The patent changes the solvent parameter from NMMO to superbase-based ionic liquids, which enable direct dissolution of cellulose from the blend without requiring prior polyester depolymerization. This parameter change simplifies the process by eliminating intermediate steps while maintaining effective cellulose separation and enabling direct fiber spinning.
5Loss of substance
If conventional recycling methods are used, then some material can be recovered, but both cellulose and polyester components are degraded
Solution Approach 1:
The patent introduces ionic liquid as an intermediary solvent that enables selective dissolution and separation of cellulose from polyester. This intermediary allows both components to be recovered in their original forms without degradation, as the ionic liquid can be removed and both cellulose and polyester maintain their structural integrity through the separation process.
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 approach enables the targeted upcycling of cellulose and non-destructive recovery of polyester, producing fibers with tenacities ranging from 25-47 cN tex-1 and allowing for the recycling of solvents and waste water, thus providing a more sustainable and efficient recycling process.
Implementation Method 1
mixing the material comprising a blend of cellulose and polyester with a first portion of superbase-based ionic liquid, e.g. DBNH OAc to dissolve a first portion of cellulose and form a first cellulose solution and a first residue comprising polyester
Data Source
AI summary
According to an example aspect of the present invention, there is provided a method of separating cellulose and polyester from a material comprising a blend of cellulose and polyester, said method comprising the steps of mixing the material comprising a blend of cellulose and polyester with a first portion of superbase-based ionic liquid to dissolve a first portion of cellulose and form a first cellulose solution and a first residue comprising polyester, removing the first residue comprising polyester from the first cellulose solution, and directing the first cellulose solution to one or more further processing steps.