Fluorinated Carboxylic Acid Purification via Low-Temperature Distillation
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Solution Overview
Problem
Conventional methods for recovering fluorinated carboxylic acids with etheric oxygen atoms from waste liquids in fluoropolymer production are inefficient, leading to high organic impurity content and reduced polymerization stability, resulting in colored and low-quality fluoropolymers.
Innovation Solution
A method involving the distillation and purification of fluorinated carboxylic acids from waste liquids, using an acid to convert the ammonium salt into the corresponding acid form, followed by extraction with an organic solvent and distillation at temperatures below 130°C to remove impurities and achieve high purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional recovery methods (acidification, heating, steam distillation) are applied to fluorinated carboxylic acids having etheric oxygen atoms, then the fluorinated carboxylic acid can be recovered, but the obtained product contains a large amount of organic impurities that are difficult to remove
Solution Approach 1:
The patent applies preliminary action by performing extraction with a specific organic solvent (dichloromethane, chloroform, or carbon tetrachloride) before distillation to remove organic impurities. This preliminary extraction step prevents the impurities from carrying over into the final product, solving the problem of difficult-to-remove organic contaminants that plagues conventional direct distillation methods.
Solution Approach 2:
The patent uses an organic solvent as an intermediary substance to separate and remove organic impurities from the fluorinated carboxylic acid. The solvent acts as a mediator that selectively extracts impurities during the extraction step, allowing the acid to be purified without direct high-temperature contact that would otherwise carry impurities into the final product.
2Quantity of substance
If conventional recovery methods are used, then fluorinated carboxylic acid can be obtained, but the organic impurities influence surface tension lowering properties and reduce polymerization stability
Solution Approach 1:
The patent performs preliminary extraction with organic solvent before the final distillation step to remove impurities that would otherwise affect polymerization stability. This advance removal of contaminants ensures that the recovered fluorinated carboxylic acid maintains its surface tension lowering properties and provides reliable polymerization stability when used as an emulsifier.
Solution Approach 2:
The patent converts the potentially harmful effect of organic impurities into a benefit by using them as extraction targets. The impurities, which would otherwise degrade polymerization stability, are selectively extracted and removed in the preliminary step, transforming the problem of impurity presence into an effective purification opportunity that enhances final product reliability.
3Quantity of substance
If conventional recovery methods are used, then fluorinated carboxylic acid can be recovered, but the obtained fluoropolymer will be colored and quality will be decreased
Solution Approach 1:
The patent applies preliminary extraction with organic solvent to remove coloring impurities and other contaminants before the final distillation and polymerization steps. This advance purification prevents the transfer of chromophoric impurities to the final fluoropolymer product, ensuring high quality and preventing discoloration that would otherwise occur with conventional direct distillation methods.
Solution Approach 2:
The organic solvent serves as an intermediary that selectively binds and removes coloring impurities and other quality-affecting contaminants during the extraction phase. This mediator substance protects the final fluoropolymer product from quality degradation by intercepting and removing harmful impurities before they can influence the polymerization process or final product appearance.
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 purifies fluorinated carboxylic acids, reducing organic impurities and improving polymerization stability, resulting in high-quality fluoropolymers suitable for industrial applications.
Implementation Method 1
adding an acid to liberate a fluorinated carboxylic acid having an etheric oxygen atom
Implementation Method 2
distillation at temperatures below 130°C to remove impurities and achieve high purity
Implementation Method 3
heating and separation into two layers, and subjecting the obtained organic liquid to steam distillation
Data Source
AI summary
To provide a method for purifying a fluorinated carboxylic acid having an etheric oxygen atom and its derivative, with small decomposition and inclusion of impurities. A liquid containing at least one member selected from the group consisting of a fluorinated compound represented by the following formula (1) and a fluorinated compound represented by the following formula (2) is held at a heating temperature of at most 150°C and distilled: RFOR1COOH (1) RFOR1COOR2 (2) RF is a linear or branched monovalent fluoroorganic group which may have an etheric oxygen atom in its main chain, R1 is a linear or branched bivalent organic group, and R2 is a linear or branched monovalent organic group. Further, the liquid is a liquid obtained from any of a waste liquid after an aqueous emulsion of a fluoropolymer is coagulated and the fluoropolymer is separated, an aqueous liquid obtained by cleaning an exhaust gas in a step of drying and/or a step of heat treatment of the separated fluoropolymer, and a liquid obtained by cleaning an anion exchange resin which has been brought into contact with the waste liquid or an aqueous dispersion obtained from the aqueous emulsion of the fluoropolymer, with an alkaline aqueous solution.