Supercritical CO2 Extraction for Depolymerized Polymer Purification
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Solution Overview
Problem
The challenge lies in purifying polymer products derived from depolymerization of plastic feedstock, specifically polyethylene, polypropylene, and polystyrene, as they often contain organic and inorganic impurities such as additives and degraded derivatives, which can result in products with dark color and petroleum odor, limiting their market applications.
Innovation Solution
A method involving supercritical fluid extraction, particularly using CO2 as the solvent, to remove impurities from depolymerized polymers by selecting the polymer, adding a solvent, heating to promote dissolution, performing extraction, depressurizing to isolate the purified polymer, and cooling, with parameters like temperature, pressure, and agitation rate optimized for effective impurity removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If depolymerization of plastic feedstock is performed to produce polymer products, then production cost is reduced and renewable polymer production is enabled, but the resulting polymer contains organic and inorganic impurities that cause dark color and petroleum odor
Solution Approach 1:
The patent applies extraction principles by using supercritical CO2 to selectively remove impurities from the depolymerized polymer product. The supercritical fluid extracts organic and inorganic contaminants while leaving the desired polymer product behind, thereby separating the harmful impurities from the useful product without requiring complex purification processes.
Solution Approach 2:
The patent utilizes parameter changes by adjusting temperature, pressure, and CO2 flow rate to optimize the extraction process. By controlling these parameters, the system achieves efficient impurity removal while maintaining polymer product quality. The supercritical state of CO2 is achieved through pressure and temperature adjustments, enabling effective extraction.
2Manufacturing precision
If conventional extraction methods are used to remove impurities, then purification can be achieved, but thermal oxidation and degradation of the polymer material occurs
Solution Approach 1:
The patent replaces conventional thermal extraction methods with supercritical fluid extraction. Instead of using heat to drive impurity removal, the system uses supercritical CO2 as a solvent that extracts impurities through diffusion and dissolution mechanisms. This substitution eliminates thermal oxidation and degradation while maintaining effective purification.
Solution Approach 2:
The patent creates an inert environment by using CO2 as the extraction solvent. CO2 is chemically inert and does not react with the polymer material or promote oxidation. This inert atmosphere prevents thermal oxidation and degradation during the extraction process, allowing purification to occur without compromising polymer integrity.
3Manufacturing precision
If multiple purification steps are implemented to remove all impurities, then product purity is improved, but process complexity and production time increase
Solution Approach 1:
The patent applies multi-functionality by using supercritical CO2 to simultaneously remove multiple types of impurities (organic compounds, inorganic particles, and colored substances) in a single extraction process. The supercritical fluid can dissolve various impurity types and the system can be configured to handle different impurity profiles, eliminating the need for multiple specialized purification steps.
Solution Approach 2:
The patent implements continuous extraction where supercritical CO2 flows continuously through the polymer material, maintaining constant extraction conditions. This continuous process ensures complete impurity removal without requiring discrete batch operations or multiple sequential steps. The continuous flow of CO2 allows for efficient, uninterrupted purification.
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 efficiently removes a high percentage of organic and inorganic impurities, improving the color and purity of the polymer products, thereby expanding their market usability and reducing production costs.
Implementation Method 1
removing organic and inorganic impurities from depolymerized polymers using supercritical fluid extraction
Implementation Method 2
heating the polymer and the solvent to promote dissolution of contaminants from the polymer into the solvent
Implementation Method 3
heating the polymer and the solvent to promote dissolution of contaminants from the polymer into the solvent
Implementation Method 4
depressurizing the reaction vessel to remove the contaminants suspended in the solvent to isolate a purified polymer
Implementation Method 5
cooling the purified polymer
Data Source
AI summary
A method for purifying polymers made from depolymerization of plastic can include selecting a polymer for purification, adding the polymer to a reaction vessel with a solvent, heating the mixture to promote migration of contaminants from the polymer to the solvent, performing an extraction technique to remove contaminants, depressurizing the reaction vessel to isolate a purified polymer, and allowing the purified polymer to cool. In some embodiments, the polymer is a polyethylene polymer. In other embodiments, the polymer is a polypropylene polymer. In some embodiments, the polymer is a polystyrene polymer. In some embodiments, the extraction technique is supercritical fluid extraction using supercritical CO2 as a solvent. Parameters including temperature, pressure, duration, agitation rate, starting solvent volume, and co-solvent addition for supercritical fluid extraction can be selected based on the properties of the polymer to be purified. The method can remove contaminating organic and inorganic compounds from the polymers.