Water-Soluble Solvent Extraction for Recycled Plastic Decontamination
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Solution Overview
Problem
Existing methods for recycling plastics fail to effectively remove non-intentionally added substances (NIAS) such as organic contaminants from the plastic matrix and surface, including degradation products, adhesive residues, and other contaminants, which are not addressed by conventional mechanical recycling or existing washing technologies.
Innovation Solution
A method using a water-soluble non-volatile solvent with a boiling point greater than 180°C at atmospheric pressure to extract organic contaminants from recycled plastics, followed by solvent recovery and recycling, including steps of extraction, rinsing, and centrifugation to ensure complete removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional mechanical recycling and washing methods are used, then physical impurities such as soil, dust, and surface contaminants can be removed, but chemical impurities including non-intentionally added substances (NIAS), adhesive residues, and contaminants within the plastic matrix cannot be effectively removed
Solution Approach 1:
The patent introduces a solvent as an intermediary substance to extract and remove chemical impurities, adhesive residues, and NIAS from the plastic matrix. The solvent acts as a mediator that selectively dissolves these contaminants while leaving the plastic matrix intact, enabling the removal of harmful chemical substances that conventional washing methods cannot eliminate.
Solution Approach 2:
The patent changes the physical-chemical parameters of the washing process by introducing a solvent with specific properties (boiling point greater than 180°C at atmospheric pressure, water-soluble, non-volatile). This parameter change enables the extraction of chemical impurities that cannot be removed by conventional water washing, thereby improving the purity of recycled plastic.
2Manufacturing precision
If volatile solvents are used for extraction, then organic contaminants can be removed, but solvent losses occur and the system becomes complex due to high pressure requirements
Solution Approach 1:
The patent changes the key parameter of the solvent from volatile to non-volatile by selecting solvents with boiling points greater than 180°C at atmospheric pressure. This parameter change eliminates solvent losses associated with evaporation and allows the extraction process to occur at atmospheric pressure, simplifying the system while maintaining effective removal of organic contaminants.
Solution Approach 2:
The patent employs a non-volatile solvent that can be easily separated from the plastic matrix through simple rinsing and centrifugation, eliminating the need for complex high-pressure separation systems. The solvent serves its purpose effectively and can be removed without causing environmental pollution or requiring sophisticated recovery systems.
3Object-affected harmful factors
If oxidation methods are used to remove contaminants, then odours and some organic compounds can be removed, but heavy contaminants and non-oxidisable organic molecules remain
Solution Approach 1:
The patent introduces a solvent as an intermediary extraction medium that can dissolve and remove a broad spectrum of organic contaminants including heavy non-volatile substances and non-oxidisable molecules. This solvent-based extraction mechanism complements oxidation methods by providing a universal removal mechanism that does not depend on the oxidisable nature of the contaminants.
Solution Approach 2:
The patent changes the removal mechanism from chemical oxidation to solvent extraction by selecting a non-volatile, water-soluble solvent with high boiling point. This parameter change enables the removal of contaminants that resist oxidation, achieving complete decontamination of the plastic matrix.
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
Effectively reduces the concentration of organic contaminants within and on the surface of recycled plastics, improving their quality and sustainability by using a solvent-based decontamination process that maintains atmospheric pressure and recycles solvents.
Implementation Method 1
extracting the non-intentionally added substances (NIAS) from the plastic matrix using a water-soluble non-volatile solvent
Implementation Method 2
centrifugation to ensure complete removal
Data Source
AI summary
The invention relates to a method for decontaminating recycled plastic materials, which comprises the steps of selecting, grinding, washing, rinsing, drying and decontaminating, wherein decontaminating is carried out by means of the steps of extracting and rinsing, and extracting is carried out using a water-soluble solvent having a boiling point greater than 180° C. at atmospheric pressure.