Phase-Transfer Catalytic Textile Fixation in Supercritical CO₂ Fluid
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Solution Overview
Problem
The traditional textile dyeing industry faces challenges in dyeing and fixing natural-fibre textiles in supercritical carbon dioxide fluid due to the hydrophobicity of the fluid, which limits the application of traditional dyes and auxiliaries, and the weak acidity of the fluid makes it difficult to improve fixation efficiency and reduce reaction temperature.
Innovation Solution
A phase-transfer catalytic fixation method using disperse reactive dyes in supercritical carbon dioxide fluid, where a phase-transfer catalyst transports an ionized alkaline substance from the aqueous phase to the hydrophobic fluid phase, facilitating a reaction with functional groups on the fibres, employing sodium hydroxide, sodium carbonate, or sodium phosphate as the alkaline substance and perfluorooctyl quaternary ammonium salt as the catalyst, under specific pressure and temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional ionic or high polarity dyes are used in supercritical carbon dioxide fluid, then the hydrophobicity of the fluid is improved, but the application of traditional dyes is greatly limited
Solution Approach 1:
The patent introduces a phase transfer catalyst as an intermediary substance that mediates between the hydrophobic supercritical carbon dioxide fluid and the ionic fixing catalyst. The catalyst has both hydrophobic and hydrophilic parts, allowing it to transport ions from the aqueous phase into the hydrophobic supercritical fluid phase, enabling the fixing reaction to proceed effectively.
2Speed
If hydrophilic fibres are placed in hydrophobic supercritical carbon dioxide fluid, then the fluid penetration is improved, but the wetting and swelling of fibres are greatly limited
Solution Approach 1:
The phase transfer catalyst acts as an intermediary that facilitates the interaction between the hydrophobic supercritical fluid and the hydrophilic fibre surface. By transporting the fixing catalyst to the fibre surface, it enables effective fixation without requiring extensive fibre wetting or swelling in the hydrophobic medium.
Solution Approach 2:
The patent changes the physical and chemical parameters of the system by using supercritical carbon dioxide fluid with specific pressure and temperature conditions. This creates a unique state where the fluid has both gas-like diffusivity for rapid penetration and liquid-like density for effective mass transfer, while the phase transfer catalyst enables chemical reactions at the fibre interface.
3Device complexity
If the fixation reaction is performed in supercritical carbon dioxide fluid without phase transfer catalyst, then the processing simplicity is improved, but the fixation efficiency is greatly limited
Solution Approach 1:
The phase transfer catalyst serves as a crucial intermediary that enables the fixation reaction to proceed efficiently in the supercritical carbon dioxide fluid system. It transports the fixing catalyst ions into the hydrophobic medium where they can react with the dye on the fibre, significantly improving fixation efficiency while maintaining relative processing simplicity.
4Use of energy by moving object
If the fixation temperature is reduced to improve energy efficiency, then the energy consumption is improved, but the reactivity of functional groups on fibres is greatly limited
Solution Approach 1:
The patent utilizes parameter changes by operating at specific supercritical conditions (pressure and temperature) of carbon dioxide. The supercritical state provides enhanced solubility and mass transfer characteristics that compensate for lower temperatures, while the phase transfer catalyst lowers the activation energy required for the fixation reaction, enabling effective fixation at reduced temperatures and improving energy 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 enhances the reactivity of functional groups on fibres, improving dye fixation efficiency and reducing processing time, making it suitable for waterless dyeing of natural-fibre textiles in supercritical carbon dioxide fluid.
Implementation Method 1
take phase-transfer catalyst as the carrier of circulated supercritical carbon dioxide fluid, then the ionized fixing catalytic alkaline substance is transported from aqueous phase to hydrophobic supercritical carbon dioxide fluid phase
Implementation Method 2
hydrophilic fibres can also get better adsorption and diffusion of dyes in the dry state without pretreatment such as wetting because the structure of the optimized dye is small
Implementation Method 3
the active groups in the dyes can react with the functional groups on fibres, so that dyes are connected with fibres by covalent bonds and fixed
Data Source
AI summary
A phase-transfer catalytic color fixation processing method for textile includes the following steps: (1) dry-dyeing a textile with disperse reactive dyes in supercritical carbon dioxide fluid under waterless condition; (2) putting the textile in a phase-transfer catalytic fixation device, taking phase-transfer catalyst as the carrier of circulated supercritical carbon dioxide fluid, transporting the ionized fixing catalytic alkaline substance from aqueous phase to hydrophobic supercritical carbon dioxide fluid phase, getting full contact with functional groups on fibers, resulting in the fixing catalytic reaction with disperse reactive dyes.