Contaminated Plastic Waste Decomposition Using Aqueous Nitric Acid
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Solution Overview
Problem
Current methods for decomposing contaminated plastic waste are inefficient, expensive, and lack economic viability, with less than 15% of global plastics being recycled due to high resource and labor requirements, and existing biological methods being costly and difficult to scale.
Innovation Solution
A method involving the addition of polyethylene plastic waste to a reaction vessel with aqueous nitric acid, followed by conditions such as temperature and pressure control, to produce decomposition products like succinic acid, glutaric acid, and nitro-substituted dicarboxylic acids, utilizing solid state catalysts and a batch or continuous process for efficient conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical recycling with thorough cleaning is used, then plastic waste can be recycled, but intensive resources and labor are required making it economically unviable
Solution Approach 1:
The patent replaces mechanical cleaning and sorting systems with a chemical treatment process using aqueous nitric acid. This chemical system automatically decomposes contaminants and functionalizes plastic surfaces, eliminating the need for labor-intensive mechanical cleaning while improving economic viability through automated batch or continuous processing.
Solution Approach 2:
The patent changes the chemical parameters of the plastic waste by treating it with aqueous nitric acid at controlled temperatures and concentrations. This transforms the plastic surface chemistry to create hydrophilic groups and functionalize the material, changing its properties from hydrophobic to hydrophilic and enabling new applications without requiring extensive mechanical preprocessing.
2Productivity
If pyrolysis is used to treat contaminated plastics, then decomposition occurs, but energy intensive processes produce low-grade fuels requiring expensive refinery steps
Solution Approach 1:
The patent changes the decomposition pathway by using aqueous nitric acid treatment at moderate temperatures instead of high-temperature pyrolysis. This chemical oxidation approach functionalizes the plastic into valuable dicarboxylic acids and other oxygenated compounds directly, avoiding the energy-intensive thermal cracking process and eliminating the need for expensive downstream refining.
Solution Approach 2:
The patent converts the harmful effect of oxidation (which typically degrades plastics) into a beneficial process by using controlled aqueous nitric acid treatment to selectively functionalize the plastic waste into valuable chemical products. Instead of complete combustion or degradation, the controlled oxidation creates useful dicarboxylic acids and hydrophilic polymers with commercial value.
3Productivity
If plastic incineration is used, then waste disposal occurs, but massive upfront capital and substantial power and maintenance are needed with adverse environmental consequences
Solution Approach 1:
The patent converts waste plastic into valuable chemical products through controlled chemical treatment with aqueous nitric acid, transforming a disposal problem into a resource recovery opportunity. This produces functionalized polymers and dicarboxylic acids with commercial applications, eliminating the need for complex incineration infrastructure and reducing environmental harm while creating economic value.
4Productivity
If biological methods are used for bioremediation, then plastic degradation occurs, but the process is expensive, inefficient, and difficult to scale
Solution Approach 1:
The patent replaces complex biological systems with a straightforward chemical treatment using aqueous nitric acid. This eliminates the need for cultivating and maintaining specialized microorganisms or insect larvae, simplifying the process to a controllable chemical reaction that can be easily scaled from laboratory to industrial production through batch or continuous processing.
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 decomposes contaminated plastic waste into valuable chemical products, enhancing recycling efficiency and reducing waste management costs, while diverting polyethylene from landfills and minimizing the use of oxidizing agents.
Implementation Method 1
adding aqueous nitric acid (HNO3) to the reaction vessel to give a mixture wherein the nitric acid has a concentration of about 67 to about 70 wt%... subjecting the mixture obtained in b. to conditions effective to decompose the plastic waste to produce decomposition products
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
This invention relates to the field of contaminated plastic waste decomposition. More specifically, the invention comprises methods and systems to decompose contaminated plastic waste and transform it into value-added products.