Polystyrene Recycling with Selective Brominated Contaminant Removal
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Solution Overview
Problem
Polystyrene waste containing brominated flame retardants is difficult to recycle due to their affinity with the polymer, leading to undesirable recycled materials, and existing methods struggle to selectively retain or remove these contaminants based on the intended use of the recycled polystyrene.
Innovation Solution
The use of specific benzenic solvents and solvent mixtures with varying alkyl substituents, combined with hydrocarbon non-solvents, allows for the differential solubility of brominated polybutadiene polystyrene copolymers, enabling their selective retention or removal through dissolution and precipitation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional recycling methods are used on polystyrene waste containing brominated flame retardants, then the recycling process can be performed with simple procedures, but the recycled polystyrene quality deteriorates due to contamination with brominated contaminants
Solution Approach 1:
The patent extracts brominated contaminants from polystyrene waste using selective solvents. The solvent system preferentially dissolves brominated polymeric flame retardants while leaving the polystyrene matrix intact, allowing separation and purification of the recycled polystyrene from harmful contaminants
Solution Approach 2:
The patent introduces a selective solvent as an intermediary substance between the polystyrene waste and the recycling process. This solvent acts as a mediator that selectively interacts with brominated contaminants, enabling their removal without affecting the base polymer
2Manufacturing precision
If brominated flame retardants are completely removed from polystyrene waste, then the recycled polystyrene quality improves, but additional processing steps and complexity are required
Solution Approach 1:
The patent changes the chemical parameters of the recycling process by using a specifically formulated solvent system with selective solubility characteristics. This parameter change enables preferential dissolution of brominated contaminants at controlled concentrations and temperatures, achieving high-quality recycling without overly complex equipment
3Loss of energy
If brominated polymeric flame retardants are retained in recycled polystyrene, then cost savings are achieved, but the recycled material becomes less desirable for certain applications
Solution Approach 1:
The patent makes the recycling process dynamic and adaptable by allowing selective retention or removal of brominated flame retardants based on the intended application. The solvent treatment can be adjusted or omitted depending on whether the recycled polystyrene will be used in applications requiring flame retardancy or where purity is paramount
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 separates brominated polybutadiene polystyrene copolymers from polystyrene waste, allowing for the production of high-quality recycled polystyrene suitable for various applications, including insulation, while retaining the copolymers when desired.
Implementation Method 1
combining the polystyrene waste with a second solvent chosen from benzenes substituted with one to four, optionally one or two, substituents each chosen from C1 to C4 alkyl, wherein at least one of the one to four substituents is isopropyl, a solvent mixture comprising about 45 wt % to about 95 wt % of a first solvent or the second solvent and about 5 wt % to about 55 wt % of a hydrocarbon polystyrene non-solvent
Implementation Method 2
to obtain a polystyrene/second solvent mixture and a solid comprising the copolymer, the hydrocarbon polystyrene non-solvent being a C5 to C8 hydrocarbon
Data Source
AI summary
The present disclosure relates to methods of removing brominated contaminants from polystyrene waste and recovering the brominated contaminants. The present disclosure further relates to methods of recycling polystyrene waste, wherein the recycling comprises retention of brominated contaminants or removal of contaminants. The present disclosure also relates to use of monocyclic aromatic benzenic solvents in the removal and/or recovery of brominated contaminants from polystyrene waste and in the recycling of polystyrene waste. Moreover, the present disclosure relates to use of the recovered brominated contaminants in the manufacture of polystyrene products such as insulation.