Packed Leaching Extraction for Plastic Contaminant Removal
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Solution Overview
Problem
Current methods for recycling plastics, particularly films, are inadequate in removing both surface and bulk contaminants to achieve the high purity levels required for demanding applications, especially due to the limitations of mechanical recycling and solvent-based purification techniques.
Innovation Solution
A method involving packed leaching extraction, where a leaching solvent is used at temperatures below the plastic's primary melting point, with a solvent-to-plastic mass ratio less than 5:1, and pressures between atmospheric and 1,000 atm, to extract contaminants like alkyl phenols, bisphenols, dioxins, and PCBs, achieving a significant reduction in contaminant concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical recycling and solvent-based purification techniques are used, then plastic recycling is achieved, but contaminant removal efficiency is insufficient for demanding applications
Solution Approach 1:
The patent applies parameter changes by operating the extraction process at temperatures below the plastic's melting point (maintaining solid state) and using elevated pressures (up to 1,000 atm) to enhance contaminant removal efficiency without requiring complex phase change equipment or multi-step processing
Solution Approach 2:
The patent directly extracts contaminants from the plastic matrix using supercritical or pressurized fluids as leaching agents, removing multiple types of contaminants (alkyl phenols, bisphenols, dioxins, PCBs) in a single integrated process step, achieving at least 55% contaminant concentration reduction
2Productivity
If higher temperatures are used to increase contaminant removal rate, then extraction efficiency improves, but plastic degradation and energy consumption increase
Solution Approach 1:
The patent changes the pressure parameter to supercritical or elevated pressure ranges while maintaining temperatures below the plastic melting point, creating a supercritical fluid environment that dramatically increases contaminant solubility and mass transfer rates without thermal degradation of the plastic matrix
Solution Approach 2:
The patent utilizes phase transition of the leaching solvent to a supercritical state under elevated pressure and temperature conditions, enabling enhanced extraction capability while maintaining process conditions that prevent plastic degradation, with the solvent returning to liquid state upon pressure release for easy separation
3Manufacturing precision
If solvent-to-plastic mass ratio is increased to improve extraction efficiency, then contaminant removal increases, but solvent consumption and process complexity increase
Solution Approach 1:
The patent uses elevated pressure (up to 1,000 atm) to increase the density and solvating power of the leaching solvent, enabling effective contaminant extraction at lower solvent-to-plastic mass ratios, thereby reducing solvent consumption while maintaining high purification efficiency
Solution Approach 2:
The patent implements a continuous extraction process where the supercritical or pressurized solvent continuously percolates through the plastic material, maximizing contaminant removal efficiency per unit of solvent and enabling solvent regeneration and reuse, reducing overall solvent consumption
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 effectively reduces contaminant concentrations by at least 55% or to the limit of quantification, producing a purer plastic suitable for use in sensitive applications, outperforming existing technologies in contaminant removal efficiency.
Implementation Method 1
extracting said individual contaminates from said first plastic... wherein said extraction is packed leaching wherein said temperature is below the primary melting point of the first plastic
Implementation Method 2
using a leaching solvent... to extract contaminants like alkyl phenols, bisphenols, dioxins, and PCBs
Implementation Method 3
wherein said pressure is between about atmospheric and 1,000 atm
Data Source
AI summary
The present invention generally relates to a method of reducing contamination from plastics. The resulting purer plastic can be used in demanding applications.