L9: Percipitation, Extraction, Ion exchange Flashcards
What are the two main methods of synthesizing succinic acid?
Chemical synthesis via butane oxidation and fermentation from sugar.
What is the theoretical carbon yield of succinic acid from sugar via fermentation?
Greater than 1, based on sugar.
What are the downstream processing (DSP) requirements for small molecules like succinic acid?
High product concentration, high downstream yield, and easy separation from water and other components.
What are the typical challenges in succinic acid recovery from fermentation?
Removing cells, cell debris, proteins, and separating succinic acid from water, fermentation broth, and byproducts (e.g., acetic, lactic, pyruvic acids).
What pH challenges are associated with succinic acid fermentation?
Succinic acid exists as a salt at neutral pH, complicating crystallization and separation.
What are the three main routes for recovering succinic acid from fermentation?
Precipitation, electrodialysis, and liquid-liquid extraction.
What is the principle behind precipitation in DSP?
Solutes are brought out of solution as solids, often through pH adjustment, salt addition, or the use of organic solvents.
Why is ammonium sulfate commonly used in protein precipitation?
It has high solubility, low density for centrifugation, and stabilizes proteins in precipitated form for long-term storage.
What are the steps in the precipitation process?
Mixing, nucleation, growth by diffusion, and growth by fluid motion.
How does ionic strength or temperature affect flocculation during precipitation?
Increasing ionic strength or decreasing temperature minimizes electrostatic repulsion, enhancing flocculation.
What are the three common designs for precipitation reactors?
Batch reactor, tubular reactor, and continuous stirred-tank reactor (CSTR).
What is electrodialysis, and how is it used for succinic acid recovery?
It separates molecules through a membrane based on charge, driven by an electrical potential difference.
What are the key advantages and challenges of using liquid-liquid extraction in DSP?
It is efficient for separating solutes, but its effectiveness depends on solvent selection, solute properties, and phase miscibility.
What is the distribution coefficient (K), and why is it important in liquid-liquid extraction?
It defines solute distribution at equilibrium between two phases; higher K values improve extraction efficiency.
What are aqueous two-phase extraction systems, and when are they used?
Systems made of water-soluble polymers or polymer-salt combinations for non-denaturing separation of proteins and cells.
What is the significance of countercurrent flow in multi-stage extraction processes?
It maximizes the solute concentration gradient, enhancing recovery efficiency.
What are common extractors used in biotechnology for liquid-liquid extraction?
Agitated extraction columns and centrifugal extractors.
What are the advantages of precipitation for protein purification?
It reduces volume, simplifies equipment needs, is inexpensive, and stabilizes proteins for storage.
How does pH adjustment aid in protein precipitation?
Proteins precipitate at their isoelectric point (pI), minimizing solubility.
Why is PEG (polyethylene glycol) used in protein precipitation?
Because it produces a nonionic environment that encourages aggregation, it decreases the solubility of proteins.
What are the benefits of batch reactors in precipitation processes?
They produce compact and regular protein precipitates.
How does the tubular reactor design compare to batch reactors for precipitation?
Tubular reactors offer continuous operation with similar particle size distribution as batch reactors over time.
What factors influence the partition coefficient in liquid-liquid extraction?
Molecule size, pH, solvent type, temperature, and phase composition.
Why is crystallization desirable for succinic acid recovery?
It provides a pure, solid product but requires high concentrations to achieve supersaturation.
