Lactic Acid Purification via Partial Conversion Electrodialysis
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Solution Overview
Problem
Current methods for producing lactic acid through fermentation struggle to achieve high purity while maintaining economical efficiency, often resulting in substantial power consumption and waste by-products.
Innovation Solution
A process involving salt exchange of magnesium lactate to form a monovalent lactate salt, followed by water-splitting electrodialysis with partial conversion and recycling of lactate salt, minimizes power consumption and waste by-products by separating lactic acid through vapour-liquid separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If water-splitting electrodialysis is used to convert lactate salt into lactic acid, then high purity lactic acid can be produced, but power consumption increases substantially
Solution Approach 1:
The patent applies partial conversion in the electrodialysis process, converting only a portion of the lactate salt to lactic acid in each pass. The unconverted lactate salt is recycled back to the electrodialysis unit, allowing the process to achieve high purity lactic acid while minimizing power consumption by avoiding complete conversion in a single pass.
Solution Approach 2:
The patent implements a continuous recycling loop where unconverted lactate salt from the electrodialysis process is returned to the electrodialysis unit for further conversion. This continuous action ensures high overall conversion efficiency and purity while distributing the energy demand across multiple passes rather than requiring excessive power in a single pass.
2Productivity
If complete conversion of lactate salt to lactic acid is achieved through electrodialysis, then high yield is obtained, but power consumption and operational costs increase
Solution Approach 1:
The patent deliberately limits the conversion in each electrodialysis pass to partial conversion (not complete conversion), accepting that some lactate salt remains unconverted. This unconverted salt is then recycled back to the electrodialysis unit, achieving high overall yield while significantly reducing the power consumption that would result from attempting complete conversion in a single pass.
Solution Approach 2:
The patent recycles the unconverted lactate salt that exits the electrodialysis process back to the electrodialysis unit for further conversion. This recovery and reuse of the unconverted material ensures high overall yield while avoiding the excessive power consumption that would result from designing the process to achieve complete conversion in one pass.
3Manufacturing precision
If ion exchangers are used to purify lactic acid, then high purity is achieved, but waste by-products are generated requiring resin regeneration
Solution Approach 1:
The patent replaces the chemical ion exchange process (which generates waste by-products requiring resin regeneration) with a physical electrodialysis process. The electrodialysis process uses ion-selective membranes and electric fields to separate and purify lactic acid without generating waste by-products, thereby achieving high purity while eliminating the need for resin regeneration and waste disposal.
Solution Approach 2:
The patent converts the challenge of having unconverted lactate salt exiting the electrodialysis process into a benefit by recycling it back to the electrodialysis unit. This approach not only achieves high purity lactic acid production without waste by-products but also ensures high overall conversion efficiency by giving the unconverted material another opportunity to be converted.
4Device complexity
If fermentation broth is directly subjected to water-splitting electrodialysis, then process complexity is reduced, but fermentation-derived impurities foul the ion-permeable membranes
Solution Approach 1:
The patent performs preliminary concentration and purification of the fermentation broth before subjecting it to water-splitting electrodialysis. This preliminary action removes or reduces fermentation-derived impurities that would otherwise foul the ion-permeable membranes, ensuring reliable and sustained membrane performance throughout the electrodialysis process.
Solution Approach 2:
The patent introduces an intermediate concentration and purification step between fermentation and electrodialysis. This intermediate process acts as a mediator that prepares the fermentation broth for electrodialysis by removing harmful impurities, thereby protecting the ion-permeable membranes from fouling while maintaining overall process efficiency.
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 process achieves high-purity lactic acid production with low power consumption and minimal waste, as all compounds can be recycled, reducing non-reusable components and maintaining process efficiency.
Implementation Method 1
subjecting the aqueous medium comprising the monovalent lactate salt to water-splitting electrodialysis, to produce a first solution comprising monovalent base and a second solution comprising lactic acid and monovalent lactate salt
Implementation Method 2
Water-splitting electrodialysis in particular allows the direct conversion of the lactate salt into lactic acid and base
Implementation Method 3
separating the second solution comprising lactic acid and monovalent lactate salt into lactic acid and a solution comprising the monovalent lactate salt by vapour-liquid separation
Data Source
AI summary
The present invention discloses a process for the preparation of lactic acid comprising the steps of: a) providing an aqueous medium comprising magnesium lactate; b) adding to the aqueous medium comprising magnesium lactate a monovalent base to form an aqueous medium comprising a water soluble monovalent lactate salt and a solid magnesium base; c) separating the magnesium base from the aqueous medium comprising the water soluble monovalent lactate salt; d) adjusting the concentration of the monovalent lactate salt in the aqueous medium to a value between 10 and 30 wt.%, e) subjecting the aqueous medium comprising the monovalent lactate salt to water-splitting electrodialysis, to produce a first solution comprising monovalent base and a second solution comprising lactic acid and monovalent lactate salt, the electrodialysis being carried out to a partial conversion of 40 to 98 mole%; f) separating the second solution comprising lactic acid and monovalent lactate salt into lactic acid and a solution comprising the monovalent lactate salt by vapour-liquid separation; g) recycling the solution of step f) comprising the monovalent lactate salt to step d).