BORSIG Membrane Technology GmbH
Liquid Separation
OSN membranes for process innovation

Organic Solvent Nanofiltration Unit

The development of solvent-resistant membranes has provided a new separation technology for the treatment of liquid organic process mixtures to the petrochemical, chemical, pharmaceutical and food industries.

Organic Solvent Nanofiltration (OSN) or organophilic Nanofiltration (oNF) membranes have a high affinity for organic solvents and retain soluted molecules in the range of 200 to 1.000 g/mol.

Unlike conventional thermal separation technologies, OSN operates at mild conditions enabling the gentle concentration of temperature-sensitive molecules as well as less energy intensive solvent recovery.

Solvent based waste streams may be processed with OSN to recover valuable components, avoid product loss and reduce waste disposal costs.

The implementation of OSN may simplify the entire process by sustituting one or more separation steps. The modular design additionally allows for flexible capacity adjustment.

Organic Solvent Nanofiltration
Organic Solvent Nanofiltration


In bulk chemistry huge amounts of solvents with high purity requirements are produced. Purifying such a solvent from a small amount of higher molecular weighted impurities by rectification is an energy-intensive and sometimes even not economic process. OSN enable to produce a highly purified solvent by retaining the impurities

Homogeneous catalysts are high value raw materials. Their recovery from reaction mixtures is quite complex and often goes along with catalyst deactivation and material losses. OSN provides a non-thermal tool for recovery of the active catalyst complex.

OSN allows for concentration of crystalline mother liquors and simultaneous recovery of the solvent. No phase change such as evaporation or condensation is required. The solvent is recovered in the liquid phase. Energy savings and improved solvent management are the benefits.

Extraction processes require high amounts of solvents which have to be removed afterwards by evaporation processes. OSN membranes offer an attractive and economic alternative for solvent recovery e.g. from hexane-oil-miscella, without undergoing a phase change.

Fragrances derived from natural oils are used in the food and cosmetic industry.

For some products there are high sensory and optic requirements. OSN membranes enable the removal of colour molecules, which can cause undesired colouring of the end-product.

The Benefits

  • Non-thermal separation process
  • Gentle separation for heat-sensitive molecules and complexes
  • Potential for energy reduction
  • Debottlenecking and process simplicication
  • Reliable and safe operation
  • Modular system


BORSIG OSN Units are mostly set-up as “Feed- and Bleed” system.

The Feed-and Bleed system consists of a circulation loop with a partial recirculation and a continuous bleed stream of the concentrate. Fresh feed mixture is fed into the loop by the feed pump to balance the concentrate bleed and the permeate stream.


For more information on OSN please visit:


Organic Solvent Nanofiltration

One of our innovative membrane technologies is Organic Solvent Nanofiltration (OSN), a new separation technology for the treatment of liquid process streams in the molecular range. OSN is a pressure driven process
that operates at moderate or ambient temperatures. The separation takes place in the liquid phase. No phase transition is required for efficient separation.

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