Method of dye clearing textiles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for removing excess dye from polyester fabric, such as reduction clearing with sodium dithionite, are hazardous, lead to persistent surfactants, and result in environmental contamination due to sulfur-containing compounds, and are not biodegradable.
Innovation Solution
A process using a weak organic acid like ascorbic acid or citric acid to remove excess dye from polyester fabric by maintaining contact at elevated temperatures and then raising the pH to between 9 and 12, eliminating the need for sulfur-containing compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sodium dithionite is used for reduction clearing, then excess dye is removed from polyester fabric, but hazardous conditions, persistent surfactants, and environmental contamination occur
Solution Approach 1:
The patent changes the chemical parameters of the clearing agent from strong reducing agents (sodium dithionite) to weak organic acids (ascorbic acid, citric acid). This parameter change maintains the dye removal effectiveness while eliminating the hazardous properties, persistence issues, and environmental contamination associated with sulfur-containing compounds
Solution Approach 2:
The patent employs weak organic acids that are biodegradable and environmentally friendly, replacing the persistent and hazardous sodium dithionite. These short-living, biodegradable substances are broken down naturally after use, eliminating the persistence problems and reducing environmental contamination in wastewater
2Reliability
If sodium dithionite is used for reduction clearing, then excess dye is removed, but sulfur-containing compounds cause persistence and biodegradability issues
Solution Approach 1:
The patent changes the chemical composition from sulfur-containing compounds to carbon-based weak organic acids. This parameter change transforms the molecular structure from persistent sulfur compounds to biodegradable organic substances that are naturally broken down by microorganisms, eliminating persistence issues while maintaining clearing effectiveness
Solution Approach 2:
The patent converts the previously harmful sulfur-containing compounds into beneficial biodegradable organic acids. These weak organic acids not only remove excess dye effectively but also serve as environmentally friendly substances that enhance rather than harm the ecosystem, turning a potential pollutant into a beneficial agent
3Reliability
If conventional reduction clearing is used, then excess dye is removed, but extensive wastewater treatment is required
Solution Approach 1:
The patent changes the chemical nature of the clearing agent from non-biodegradable sulfur compounds to biodegradable weak organic acids. This parameter change fundamentally alters the wastewater characteristics, making it much easier to treat through conventional biological treatment processes and reducing the complexity and cost of wastewater treatment facilities
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 safely and effectively removes excess dye, reduces environmental pollution, and improves dye fastness without the hazards and persistence issues of sulfur-containing compounds, while being more cost-effective and environmentally friendly.
Implementation Method 1
The process of removing excess dye that serves to eliminate these problems is called reduction clearing. Reduction clearing usually uses a strong reducing agent at a high temperature and pH to remove excess dye.
Implementation Method 2
adding a solution of a weak organic acid or a salt thereof to the fabric in a dyeing vessel, raising the temperature and allowing the acid or salt thereof to remain in contact with the fabric for a period of time
Implementation Method 3
The pH is then raised to between pH 9 and pH 12 after the reduction clearing treatment using a weak acid
Data Source
AI summary
A process to remove excess dye from dyed polyester fabric comprising adding a solution of a weak organic acid to the fabric in a dyeing vessel, raising the temperature in the vessel to at least 80 °C, allowing the acid to react with the fabric for at least 6 minutes and removing all liquid.