Organic solvent nanofiltration

Evonik's OSN membranes for fine chemistry and pharma applications

Evonik's PuraMem® stand for innovative membranes for organic solvent nanofiltration. These OSN membranes provide efficient separations at near-ambient temperatures without the need for a phase change of the liquid feed.


Processing APIs and their intermediates at lower (ambient) temperature minimises damage to these often complex molecules. APIs and intermediates can be concentrated or purified using OSN membranes without exposure to damaging heat.

Active Pharmaceutical Ingredients (APIs) and their intermediates are typically complex molecules that are produced in multi-stage syntheses. To produce these molecules in high purity and high yield it is essential to minimise losses in each reaction and separation step. The complex nature of these species makes them temperature sensitive – heat damage during synthesis and separation can reduce yield, reduce purity or reduce both. Separations such as concentration or purification operations can be carried out effectively with OSN membranes at relatively low temperatures (ambient temperature or below). Molecules of 200+ Da molecular weight can be retained by OSN membranes which allows smaller molecules to be separated from larger molecules, i.e. purification, or the target molecule can be retained by the membrane and concentrated. Evonik’s range of DuraMem® and PuraMem® OSN membranes can be used for these applications.

Non-thermal Solvent Recovery

Our PuraMem® range of OSN membranes provide the separation capability for recovering process solvents without the need for heating and cooling. Solvents can be recovered at high purity with an energy-efficient OSN process.

Evonik has developed the PuraMem® range of OSN membranes for applications in a very broad range of organic solvents. By selection of the appropriate membrane, both inorganic chemicals and organic compounds (200+ Da molecular weight) can be highly retained by the OSN membrane allowing high purity solvent to pass through the membrane. This allows solvent of >99% purity to be recovered at high yield without the need to evaporate and condense the solvent. This provides a significant saving in energy consumption versus conventional evaporation or distillation unit operations.


Many fine chemical synthetic routes require the process solvent to be exchanged for different reaction types. OSN membranes allow the solvents to be switched at room temperature without using conventional thermal techniques.

OSN membranes are capable of retaining a wide variety of intermediate or product molecules (200+ Da molecular weight) while allowing solvents to pass through the membrane. A solvent exchange can be affected by allowing the initial solvent to permeate the membrane at room temperature and adding the second (switch) solvent to the filtration system. As the filtration progresses, the second solvent replaces the first solvent leading to an effective method of generating the desired solvent exchange. This is particularly effective if the second solvent boils at a lower temperature than the first solvent, which is challenging to achieve via conventional thermal technologies. Evonik has developed the PuraMem® range of OSN membranes, which can be utilised for a broad range of solvent exchanges.

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