Process with supercritical fluid in the pharmaceutical, cosmetic and food sectors

In the life science area, processing is increasingly done with fluids in the supercritical aggregate condition.

The advantage of these processes is in the use of solvents that are environmentally friendly and non-damaging to the product, mainly carbon dioxide. The requirements of the pharma & biotech markets are met by working at low temperatures and moderate pressures (gentle handling of the product).

The requirements for the metering and process diaphragm pumps are very specific in these applications.


LEWA metering pumps and process diaphragm pumps are very well suited for supercritical processes, since they meet all the relevant requirements.

Advantages of LEWA pumps:

  • Hermetically tight
  • Layout of high pressure pumps and their peripheral equipment for liquid gases (refrigeration equipment)
  • Suitable for thin, non-lubricating fluids
  • High operational reliability
  • Low wear, almost no particle contamination due to minimal movement of pump head parts
  • Easy to clean, food design available
  • Hygienic design possible for pharmaceutical applications (Ra < 0.5 μm electro-polished, ASME BPPE, EHEDG)
  • Installation in GMP areas/clean rooms
  • Material conforms to FDA (GRAS: Generally Recognized As Safe)
  • Installation possible in potentially explosive areas
  • Optimum pump head material, for example Hastelloy, available for highly corrosive media
  • Diverse connection geometries
  • Custom valves possible
  • Documentation on qualification/validation
  • Tested for wafer cleaning (Fraunhofer IPA Tested Device®)

It must be noted that carbon dioxide must be in the liquid state to be pumped. This is not practical in the gaseous state due to its compressibility.

Areas of application

LEWA metering pumps and process diaphragm pumps have been successfully used in the following processes:

  • Extraction processes with supercritical CO2 (Supercritical Fluid Extraction SFE), such as decaffeination, degreasing, phytoextraction, as well as the extraction of oil seed, omega fish oil, flavors and spices
  • Supercritical preparative liquid chromatography (Supercritical Fluid Chromatography SFC), as well as separation of optically active substances
  • Supercritical Fluid Reactions SFR
  • Particle formation (e. g., Particles from Gas Saturated Solutions PGSS), such as high-pressure spraying process for pulverizing greases, baked goods, etc.
  • Cleaning processes, e.g., process integrated separation of substances, such as pesticide removal (wool grease, lanolin)
  • Cell breakdown, inactivation (gentle sterilization)
Überkritische Fluide, CO2 Anwendungen

Industrial scCO2-Applications

Principle of the PGSS process:

  1. Conditioning and melting two reactants 1 and 2
  2. Feed and compression with LEWA high pressure pumps P1, P2 and P3
  3. Mixing both reactants with supercritical fluid in a static mixer (SM)
  4. Decompression in a spray tower (SP) via a nozzle
  5. Droplet formation
  6. Cooling of droplets and particle formation
  7. Generation of powder in the spray tower with cyclone (ZK)
Extraktion mit überkritischen Fluiden, Prozessschema

Illustration: Principle of the PGSS process

Source: Department of Process Technology, Transport processes, and particle design - technology, University Bochum




A supercritical fluid is a substance whose temperature and pressure are both over their critical point simultaneously (see diagram for CO2).

The critical temperature is the temperature over which the substance can no longer remain liquid, regardless of the pressure level.

Critical pressure is the pressure over which the substance can no longer form gas, regardless of the temperature.

Supercritical fluids have the density and good dissolving properties of fluids, as well as the viscosity, good compressibility, and diffusability of gases.

Due to their good mixing and mass transfer properties, they are classed as a fluid.

Important advantages of supercritical fluids:

  • Safe, cost-effective, environmentally friendly, non-toxic
  • They can replace organic solvents
  • Good influence over slight changes in operating conditions
  • Operating conditions under low temperature and pressure make them attractive for research and development in the pharmaceutical & biotechnology sector.

Selection criteria for the right supercritical fluid:

  • Physical-chemical properties of the desired mixture
  • Task of the solvent in the process in regards to solubility
  • Specific application
  • Safety, especially in regards to flammability, phase behavior under operating conditions
  • Cost of the fluid
  • Cost of the equipment

The most frequently used supercritical fluid is CO2.

Properties of carbon dioxide:

  • Low critical temperature (31.1°C)
  • Moderate critical pressure (73 bar)
  • Non-flammable
  • Non-toxic
  • Mixable with organic solvents
  • Recoverable after processing
  • Diffuses faster than conventional fluid solvents
  • GRAS status
  • Approved by the FDA for use in food and pharmaceuticals
  • Environmentally friendly
  • Cost-effective

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