Subcritical Water Cellulose Extraction from Cotton Blends
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Solution Overview
Problem
The recycling of textile fibers is hindered by the complexity of fiber mixtures and fluctuations in molecular properties of cellulose, leading to high costs and inefficient processing methods that result in low-quality cellulose products.
Innovation Solution
A method involving the treatment of cotton or cotton-PET blends with subcritical water in a reactor at temperatures of 130-180°C and pressures of 1-10 bar for 1-120 minutes to produce high-purity cellulose with a predetermined average degree of polymerization (DP) of 300-1000, preferably 450-650.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aggressive additives (acids and/or bases) are used as catalysts in the processing of cotton into cellulose, then the processing efficiency is improved, but the quality of the end product deteriorates due to unstable polymer fibers and undesirable by-products
Solution Approach 1:
The patent changes the fundamental processing parameters by replacing aggressive chemical catalysts with subcritical water conditions (temperature 100-200°C, pressure corresponding to saturated vapor pressure). This parameter change enables efficient cellulose extraction while maintaining polymer stability and avoiding harmful by-products, thus resolving the contradiction between processing efficiency and product quality
Solution Approach 2:
The patent introduces subcritical water as an intermediary medium that facilitates the extraction of cellulose from cotton without requiring aggressive acids or bases. The subcritical water acts as a gentle yet effective catalyst and solvent, enabling high processing efficiency while preserving the quality and stability of the cellulose polymer fibers
2Manufacturing precision
If complex separation processes are used to handle fiber mixtures, then the purity of cellulose is improved, but the device complexity and processing cost increase
Solution Approach 1:
The patent directly extracts pure cellulose from cotton or cotton blends using subcritical water treatment, obtaining cellulose with at least 90% purity in a single integrated process. This extraction approach eliminates the need for complex multi-step separation processes, thereby maintaining high purity while reducing device complexity and processing costs
Solution Approach 2:
The subcritical water treatment process serves multiple functions simultaneously: it acts as a catalyst, solvent, and purification medium in one integrated step. This multi-functional approach replaces what would otherwise require multiple separate processing stages, simplifying the overall device complexity while achieving high cellulose purity
3Productivity
If energy-consuming processing steps are used to process textile waste material, then the cellulose extraction efficiency is improved, but the energy consumption increases
Solution Approach 1:
The patent utilizes subcritical water conditions (temperature 100-200°C, pressure corresponding to saturated vapor pressure) to optimize the extraction efficiency. This parameter range achieves high cellulose extraction efficiency while avoiding excessive energy consumption associated with higher temperature processes, thus resolving the contradiction between productivity and energy use
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 enables the production of high-quality cellulose with a purity of at least 90% and a controlled DP range, facilitating the production of high-purity cellulose products like viscose and lyocell without the need for aggressive additives or complex separation processes.
Implementation Method 1
an educt of cotton or of a mixture of cotton and PET with a fiber length of at most 1 mm is treated in a reactor with subcritical water at a temperature of 130-180° C. and a pressure in a range of 1-10 bar
Implementation Method 2
treated in a reactor with subcritical water at a temperature of 130-180° C. and a pressure in a range of 1-10 bar for approx. 1-120 min wherein a cellulose polymer with an average degree of polymerization (DP), which can be predetermined, of 300-1000 DP
Data Source
AI summary
A method for the production of a cellulosic polymer with a cellulose content of at least 92% from textile waste material, wherein an educt of a mixture of cotton and PET with a fire length of at most 1 mm is treated in a reactor with subcritical water at a temperature of 130-200° C., particularly preferably between 160° C.-200° C. and a pressure in a range of between 1-25 bar, preferably between 1-10 bar for about 1-120 mins and wherein a cellulose polymer with an average degree of polymerisation of between 450-650 is formed.