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Fractionation of liquid mixtures, pastes or dispersions with supercritical carbon dioxide

Fractionation is the process of separating a mixture into its individual components based on differences in their physical or chemical properties. Supercritical CO2 serves as an excellent solvent for this purpose due to its unique properties :

  • Tunability: By adjusting temperature and pressure, the solvating power of CO₂ can be fine-tuned to selectively dissolve specific components.
  • Low Viscosity and High Diffusivity: These properties enhance mass transfer rates, making the fractionation process more efficient.
  • Environmental Benefits: CO₂ is non-toxic, non-flammable, and can be recycled within the process, reducing environmental impact.

CO2 can be used in the fractionation of liquid mixtures in both packed columns and thin film devices. The later is an innovative approach that offers efficient and environmentally friendly solutions for separating complex mixtures, especially those that are viscous or granular yet still flowable.

Grafik Extraction of liquid raw materials

Packed Column Fractionation

A packed column is a vertical cylindrical vessel filled with packing materials such as rings, saddles, or structured packings. These materials provide a large surface area for interaction between the liquid mixture and the supercritical CO₂.

How the Column Works in Relation to Mass Transfer

  • Counter-Current Flow: The liquid mixture is introduced at the top of the column, while supercritical CO₂ enters from the bottom.
  • Mass Transfer Mechanism: As the two phases flow past each other, components from the liquid phase diffuse into the CO₂ phase. The packing materials enhance contact and mass transfer efficiency.
  • Separation: The CO₂ laden with dissolved components exits the top, where pressure reduction allows for the recovery of the solutes. The depleted liquid exits the bottom of the column.

Substances Suitable for Fractionation Using Packed Columns

  • Edible Oils and Fats: Separation of specific triglycerides, fatty acids, or removal of contaminants like pesticides.
  • Essential Oils and Flavors: Extraction and purification of aromatic compounds from plants.
  • Pharmaceutical Compounds: Isolation and purification of active ingredients from complex mixtures or fermentation broth.
  • Polymers: Removal of residual monomers or solvents from polymer solutions.
  • Natural Extracts: Separation of bioactive compounds such as antioxidants, pigments, and vitamins.

Thin Film Device Fractionation

Thin film devices, such as wiped film evaporators, are designed for mixtures that are too viscous or granular for traditional packed columns.

  • Thin Film Formation: The liquid mixture is spread into a thin film over the internal surface of the thin.film equipment
  • Enhanced Mass Transfer: The thin film increases surface area and reduces diffusion distances, facilitating efficient mass transfer with supercritical CO₂.
  • Processing Viscous Mixtures: The mechanical agitation allows for the handling of high-viscosity fluids or dispersions.

Mixtures That Can Be Processed

  • Pastes: Such as peanut or other nut-pastes

  • High Viscosity Oils: Such as omega-3 rich fish oils or heavy vegetable oils.

  • Polymer Melts: Removal of solvents or low-molecular-weight fractions from molten polymers.

  • Dispersions and Emulsions: Separation of phases or extraction of specific components from complex mixtures.

Our Expertise at NATEX Prozesstechnologie GesmbH

At NATEX Prozesstechnologie GesmbH, we possess extensive knowledge and experience in developing high-pressure processes utilizing supercritical CO₂. Our capabilities include:

  • Process Development: Tailoring fractionation processes to specific mixtures and desired outcomes.
  • Pilot Plant Facilities: We have a pilot packed column and thin film devices that allow us to conduct experimental trials and optimize processes.
  • Scale-Up Expertise: Our experience ensures that processes developed at the pilot scale can be safely and effectively scaled up to industrial levels.

At NATEX Prozesstechnologie GesmbH, we are committed to advancing this field and providing our clients with innovative solutions backed by practical experience and state-of-the-art facilities.