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Identify the continuous liquid phase
Organic compounds in a water-based feed do not automatically require an organic solvent nanofiltration membrane. For OSN, the solvent itself is central to selection. Confirm solvent identity, mixture proportions, water content, temperature and concentration, including changes during concentration and cleaning.
Membranes, adhesives, seals and all wetted equipment materials must be compatible with the actual liquid. A solvent name on a screening list is not blanket confirmation of compatibility at every concentration and temperature.
Read OS reference data in context
The published OS reference cut-off is 100 Da, with reference flux of 65 LMH and MgSO4 rejection of at least 99.5%. These values use an aqueous test at 40 bar, 30°C and 0.2% MgSO4; flux may vary by approximately ±20%. They do not establish flux or solute rejection in the intended organic solvent.
Published limits include a maximum pressure of 70 bar, maximum pressure drop of 0.5 bar, filtration and cleaning temperature up to 60°C, filtration pH 2–12 and cleaning pH 1–13. Confirm their applicability to the selected element and solvent before setting operating conditions.
Evaluate the whole solvent cycle
Methanol, ethanol, propanol, acetone, acetonitrile, hexane, ethyl acetate, THF and DMF are examples for compatibility investigation. Mixture composition and solubility can change as the solvent passes through the membrane; solvent switching can also cause precipitation. Test retention, flux, product yield, cleaning and repeated operation with the actual mixture.
OSN can complement distillation, extraction and crystallization. Select the combined route using product and solvent mass balances, sustained operating data and project-specific equipment and solvent-handling requirements.
DoisTec technical comparison