Quaternary Phosphonium Arylcarboxylate Solvents for Carboxylic Acid Extraction
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Solution Overview
Problem
Current methods for recovering C1 to C4 carboxylic acids from aqueous streams face challenges due to unfavorable vapor-liquid equilibrium and high energy costs, with existing solvents exhibiting poor partitioning and high costs, particularly for acetic acid extraction.
Innovation Solution
The use of quaternary phosphonium arylcarboxylates as extraction solvents, which demonstrate high acid partition coefficients and selectivity for C1 to C4 carboxylic acids, enabling efficient separation from water and reducing the need for high solvent volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional organic solvents are used for extraction, then the extraction process can proceed, but the partition coefficient is low requiring high levels of solvent and the selectivity between carboxylic acid and water is poor
Solution Approach 1:
The patent changes the chemical structure parameters of the solvent by using quaternary phosphonium cations with specific alkyl chain lengths (C12-C20) and arylcarboxylate anions, which fundamentally alters the solvent's interaction properties with carboxylic acids and water, achieving high partition coefficients and selectivity
Solution Approach 2:
The invention uses composite ionic liquid systems combining quaternary phosphonium cations with specific arylcarboxylate anions (such as p-toluenesulfonate, mesylate, or trifluoromethanesulfonate), creating a tailored solvent composition that achieves both high partition coefficient and selectivity for carboxylic acid extraction
2Device complexity
If simple distillation is used to recover glacial acids, then the process is simple, but the vapor-liquid equilibrium is unfavorable and energy costs are high
Solution Approach 1:
The ionic liquid acts as an intermediary extraction solvent that preferentially binds carboxylic acids from the aqueous phase, creating a concentrated extract phase that can then be processed more efficiently. This intermediary step overcomes the unfavorable VLE of direct distillation by first concentrating the acid in a separate phase
Solution Approach 2:
The process utilizes liquid-liquid phase separation between the ionic liquid extractant and the aqueous feed, creating distinct phases that allow for efficient separation. The phase transition from a single aqueous phase to two liquid phases enables selective acid concentration before final recovery
3Reliability
If extraction is performed to partition carboxylic acid into water-immiscible solvent, then bulk water is removed, but the solvent must be immiscible with water and show sufficient affinity and capacity for the lower carboxylic acid
Solution Approach 1:
The patent optimizes the hydrophobicity parameter of the phosphonium cation by selecting alkyl chains of C12-C20 length, which provides sufficient water immiscibility while maintaining adequate solubility for carboxylic acids through the balanced hydrophobic-hydrophilic character of the ionic liquid
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 approach significantly enhances the extraction factor, leading to lower capital and energy costs and improved recovery efficiency of lower carboxylic acids, particularly at low acid concentrations, facilitating energy-efficient and cost-effective separation.
Implementation Method 1
The composition comprises (a) a quaternary phosphonium arylcarboxylate salt and (b) a non-ionic organic solvent... The equilibrium partition coefficient for component A (the lower carboxylic acid) is defined as follows: K = [A]organic/[A]aqueous. The partition coefficient is a measure of the relative concentrations of the solute to be extracted in the two phases.
Data Source
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AI summary
This invention relates to solvents for extracting Cito C^arboxylic acids from aqueous streams. More specifically, the extraction solvents include one or more salts composed of a phosphonium cation and an arylcarboxylate anion. The extraction solvents may further include one or more non-ionic liquid organic solvents as an enhancer. The extraction solvents are useful for extracting aqueous mixtures containing one or more lower carboxylic acids, such as monocarboxylic acids, alkoxycarboxylic acids, and halogen-containing carboxylic acids. Formula (I)