Textile recycling
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Solution Overview
Problem
Current textile recycling methods are inefficient and environmentally harmful, particularly for polyester/cotton blends, as they often use toxic solvents like DMSO or hydrochloric acid, leading to significant cotton waste and energy consumption, and do not effectively recycle cellulose fibers, resulting in substantial textile waste ending up in landfills.
Innovation Solution
A method utilizing ionic liquids, such as N-Methylmorpholine-N-oxide (NMMO), 1-Allyl-3-methylimidazolium chloride (AMIM-CL), and 1-butyl-3-methylimidazolium acetate (BMIM-OAc), to dissolve cellulose fibers from textile blends, allowing for their separation and re-spinning into high-quality, virgin-like fibers, while avoiding the use of toxic chemicals and minimizing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DMSO is used to dissolve polyester, then polyester can be separated, but the process becomes toxic and requires high temperatures
Solution Approach 1:
The patent changes the chemical parameter by substituting DMSO with ionic liquids (specifically imidazolium-based ionic liquids), which have different solvation properties. This allows polyester dissolution and separation to occur at lower temperatures while eliminating the toxicity associated with DMSO, thus resolving the contradiction between effective separation and harmful factors
Solution Approach 2:
The patent converts the previously harmful high-temperature requirement into a benefit by using ionic liquids that enable dissolution at milder conditions. The ionic liquids' unique properties (low volatility, high thermal stability, and tunable solvation) transform the process from harmful to beneficial, achieving effective polyester separation without toxicity or excessive energy consumption
2Reliability
If hydrochloric acid is used to hydrolyze cotton, then cotton can be separated, but a substantial portion of cotton is wasted
Solution Approach 1:
The patent changes the chemical parameter by replacing hydrochloric acid with ionic liquids. The ionic liquids selectively dissolve polyester through coordination interactions without hydrolyzing or degrading the cotton cellulose structure. This preserves the cotton fibers in their intact form, eliminating the substantial cotton waste that occurs with acid hydrolysis while maintaining effective separation
Solution Approach 2:
The ionic liquid acts as an intermediary substance that mediates the separation process. It selectively interacts with polyester components through its cation-anion pairs, dissolving only the polyester while leaving cotton untouched. This intermediary approach enables precise selective dissolution without the non-selective destructive action of strong acids on cotton
3Productivity
If conventional recycling methods are used, then some textile waste is recovered, but only 1% is chemically recycled and most ends up in landfills
Solution Approach 1:
The patent creates a universal chemical recycling system using ionic liquids that can process multiple types of textile waste, particularly polyester-containing blends. The method simultaneously achieves fiber separation, purification, and regeneration in one process flow, enabling chemical recycling of a much broader range of textiles compared to conventional methods, thus dramatically increasing the productivity of waste recovery
Solution Approach 2:
The patent implements a complete recovery system where textile waste is not discarded but fully recovered and regenerated. The ionic liquid process dissolves polyester, separates it from natural fibers, and then regenerates both components into high-quality reusable fibers. This closed-loop approach converts what would be landfill waste into valuable recovered materials, eliminating the 99% loss rate of conventional recycling
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 energy-efficient, environmentally benign recycling of cellulose fibers, reducing textile waste, conserving resources, and producing fibers indistinguishable from virgin ones, thereby addressing the inefficiencies and environmental concerns of existing methods.
Implementation Method 1
dissolve cellulose fibers from textile blends
Data Source
AI summary
A textile recycling method receives textile-waste-to-be-recycled, sorts the waste to isolate cellulose-containing articles from non-cellulose-containing articles, and re-sizes at least some of the cellulose-containing articles to create feedstock. The feedstock is processed in a cellulose solvent reactor, which has at least one ionic liquid. The ionic liquid dissolves intermolecular cellulose bonds of the feedstock to create a spinning dope. Cellulose fibers dissolved in the cellulose-bearing spinning dope solution are extruded in a cellulose coagulation bath reservoir to reconstitute at least some of the cellulose fibers, and the reconstituted fibers are wet-spun to form a continuous cellulose thread that is commercially indistinguishable from virgin fiber thread. Synthetic fiber material is vacuum-extracted or mechanically extracted from the cellulose-bearing solution and recycled into a continuous synthetic thread. Original color of textile-waste-to-be-recycled can be retained or removed, and new color can be added.