Propionic Acid Recovery via Liquid-Liquid Extraction
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Solution Overview
Problem
Current methods for producing propionic acid from glycerol face challenges such as low yield, productivity, and difficulties in purification due to acidic pH inhibition and the presence of by-products, making microbial production economically non-competitive with petrochemical routes.
Innovation Solution
A method involving acidification of the aqueous mixture to pH below 4.5, followed by extraction with a heavy extractant and optional light extractant as a diluent, and subsequent vacuum evaporation to separate propionic acid, allowing for the recovery and purification of propionic acid without the need for filtration steps and achieving high product purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If propionic acid is produced by propionibacteria via the dicarboxylic acid pathway, then propionic acid can be obtained from renewable resources, but low yield and productivity occur due to inhibition of propionic acid on cell growth and synthesis
Solution Approach 1:
The patent applies liquid-liquid extraction to remove propionic acid from the fermentation broth as it accumulates. The organic solvent extracts propionic acid from the aqueous phase, reducing the inhibitory concentration in the fermentation medium and allowing continuous high-yield production without cell growth inhibition
Solution Approach 2:
The patent introduces an organic solvent as an intermediary substance that mediates the transfer of propionic acid from the aqueous fermentation broth to the organic phase. This intermediary enables selective separation and concentration of propionic acid while maintaining favorable conditions for microbial growth
2Quantity of substance
If extractive propionic acid fermentation is used to alleviate inhibition, then propionic acid production can proceed at higher concentrations, but the process becomes more complex with additional extraction steps
Solution Approach 1:
The patent combines the fermentation and extraction processes into a unified system where extraction occurs continuously during fermentation. The organic solvent is introduced directly into the fermentation reactor, merging two separate unit operations into one integrated process that simplifies overall complexity
Solution Approach 2:
The patent implements continuous extraction during the fermentation process rather than batch extraction after completion. The organic solvent continuously removes propionic acid as it is produced, maintaining constant extraction action throughout the entire fermentation period and enabling sustained high concentrations
3Productivity
If conventional chemical synthesis from petroleum feedstocks is used, then propionic acid can be produced efficiently, but it cannot utilize renewable resources
Solution Approach 1:
The patent changes the fundamental parameter of feedstock type from petroleum-based to biomass-based (lignocellulosic materials). By modifying the carbon source parameter while maintaining efficient fermentation and extraction processes, the system achieves both renewable resource utilization and high production efficiency
Solution Approach 2:
The patent creates a versatile production system that can utilize various renewable feedstocks (lignocellulosic biomass, agricultural waste, etc.) not just specific substrates. The combined fermentation-extraction platform is adaptable to multiple carbon sources, providing universal applicability across different renewable resources
4Stability of the object's composition
If propionic acid fermentation is performed at acidic pH to maintain product stability, then propionic acid can be preserved, but microbial growth and propionic acid synthesis are inhibited
Solution Approach 1:
The patent segments the system into two distinct phases: an aqueous phase for fermentation where microorganisms grow at near-neutral pH, and an organic phase for propionic acid extraction. This segmentation allows the fermentation environment to maintain conditions optimal for microbial growth while the extracted propionic acid remains stable in the organic phase
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 enables the efficient recovery and purification of propionic acid, allowing for the recycling of remaining glycerol and extraction diluent, resulting in a superior product purity and economic feasibility of bio-based propionic acid production.
Implementation Method 1
subjecting the aqueous mixture to an extraction with extracting agent comprising a heavy extractant and optionally a light extractant as a diluent to obtain an extract containing the extracting agent and organic acids
Implementation Method 2
subjecting the extract to vacuum evaporation to separate propionic acid-containing organic acids from the extractant
Implementation Method 3
subjecting the extract to vacuum evaporation to separate propionic acid-containing organic acids from the extractant
Data Source
AI summary
The present invention provides a method for purifying and recovering propionic acid from an aqueous mixture containing a fermentation product obtained from a fermentation process using glycerol as substrate, the method comprising optionally acidifying the aqueous mixture to a pH below 4.5, subjecting the aqueous mixture to an extraction with extracting agent containing a heavy extractant and optionally a light extractant as a diluent to obtain an extract comprising the extracting agent and organic acids, and a raffinate comprising water and any unreacted glycerol, and subjecting the extract to vacuum evaporation to separate propionic acid-containing organic acids from the extractant.