Hydrothermal Recycling of Polyester Cotton Blends
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Solution Overview
Problem
Conventional methods for recycling polyester-cotton blended fabrics require harmful substances or expensive solvents, leading to environmental burden and high production costs.
Innovation Solution
A recycling method using a hydrothermal reaction with a mixed aqueous solution of organic or inorganic acids and metal catalysts under controlled conditions to separate and recover polyester and cotton fibers efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional separation methods use harmful substances or expensive solvents as catalysts, then the separation of polyester and cotton fibers can be achieved, but the environmental burden increases and production costs rise
Solution Approach 1:
The patent changes the parameters of the reaction system by using mild organic acids (formic acid, acetic acid, oxalic acid, tartaric acid, citric acid, or methanesulfonic acid) instead of strong mineral acids, and employs metal catalysts (CuCl2, Ni(NO3)2, Co(NO3)2, FeCl3, or ZnCl2) to enable the reaction to proceed at lower temperatures (110-160°C) and pressures (1.5-12 bars), thereby reducing environmental burden while maintaining separation effectiveness
Solution Approach 2:
The patent employs inexpensive metal catalysts and organic acids that can be used in relatively high quantities (0.1-10 wt% acidic compound and 0.1-5 wt% metal catalyst based on total weight of mixed aqueous solution) to replace expensive and harmful conventional catalysts, making the process more environmentally friendly and cost-effective
2Reliability
If conventional separation methods use harmful substances or expensive solvents, then the separation of polyester and cotton fibers can be achieved, but the production cost increases
Solution Approach 1:
The patent optimizes reaction parameters including temperature (110-160°C), pressure (1.5-12 bars), and reaction time (1-6 hours) to achieve effective separation using inexpensive reagents, thereby reducing production costs while maintaining separation effectiveness
Solution Approach 2:
The patent uses cheap metal catalysts and organic acids that are readily available and inexpensive, replacing expensive conventional solvents like NMMO, thereby significantly reducing production costs
3Productivity
If the reaction is carried out at high temperatures, then the separation process can be completed, but the energy consumption increases and environmental burden worsens
Solution Approach 1:
The patent changes the temperature parameter from conventional high temperatures to a milder range (110-160°C) by introducing metal catalysts and organic acids that lower the activation energy of the hydrolysis reaction, thereby reducing energy consumption and environmental burden while maintaining reaction completion
Solution Approach 2:
The patent introduces metal catalysts and organic acids as intermediaries that facilitate the hydrolysis of cotton fibers at lower temperatures, acting as mediators between the aqueous solution and the fabric to enable effective separation under milder conditions
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
The method reduces production costs and environmental impact by shortening process time and lowering reaction temperatures while achieving high PET recovery rates.
Implementation Method 1
a recycling method using a hydrothermal reaction with a mixed aqueous solution of organic or inorganic acids and metal catalysts under controlled conditions to separate and recover polyester and cotton fibers efficiently
Implementation Method 2
a mixed aqueous solution of an acidic compound and a metal catalyst is added, a temperature is raised to 110° C. to 160° C., and a reaction is carried out for 1 to 6 hours to cleave the cotton fibers
Data Source
AI summary
The invention provides a recycling method of polyester cotton blended fabrics, which includes the following steps. First, the polyester cotton blend fabric is cuts into fragments. Afterwards, the fragments are placed in a reactor, a mixed aqueous solution of an acidic compound and a metal catalyst is added, a temperature is raised to 110° C. to 160° C., and a reaction is carried out for 1 to 6 hours to cleave the cotton fibers. Next, filter and separate to obtain cotton powders and a polyester fiber.