Evonik's OSN membranes for efficient processing of hemp and cannabis

Evonik offers TWO STEP membrane-based organic solvent nanofiltration for efficient processing of cannabis.

Evonik’s OSN membrane technology of PuraMem® and DuraMem® allows Hemp/Cannabis processors to eliminate the winterization process and substantially reduce the decolorization and evaporation steps, thus leading to significant reductions in processing costs and improvements in yield and quality.

TWO STEP membrane-based organic solvent nanofiltration for efficient processing of cannabis


  • Faster and Simpler Processing - Elimination of Winterization – 100% wax, lipids, fats removal at ambient temperature.
  • Higher Purity, Quality and Yield of CBD/THC - Non-thermal processing also ensures the option of THCA / CBDA as an end product is available.
  • Lower Solvent Volume - Desolvation down to 3:1 or 4:1 can be achieved which represents 70-90% ethanol removal (depending on the starting concentration).
  • Lower OPEX and CAPEX - Evonik's OSN is easily scalable .

Faster and Simpler Processing of Cannabis

Frequently Asked Questions

  • For STEP 1, what is the dilution required?
    Dilution of 10:1 to 20:1 can be used (i.e. 20 parts solvent to 1 part CBD oil). We would recommend using a dilution of 20:1
  • What is the processing rate of your largest module?
    Our largest module is 8” in diameter and 40” in length and can process at an average permeate rate of 30 gallons/hr (125 L/hr).
  • But our requirement is higher?
    You can use multiples of the 8” modules to meet your requirements.
  • But our requirement is lower?
    You can use our 4” module or multiples of it. One 4” module processes at 6 gallons / hr (25 L/hr).
  • What temperatures and pressures are membranes operated at?
    You can operate at up to 50°C but normal operating temperature is ambient. Our membranes can be run at up to 60 bar (900 psi). Usual operating pressures are around 30 – 50 bar (450 – 750 psi). (Membranes can be operated at colder temperatures also but permeation rates would be slower)
  • How about OSN-2?
    Co-incidentally, the OSN-2 has similar permeate rates to OSN-1 and it is operated at similar temperatures and pressures to OSN-1. (Again, these rates are pertinent to ethanol)
  • How concentrated can I get?
    Typically, you can get down to ~ 3:1, but it depends a great deal on your specific composition.
  • So, I still need to do evaporation?
    Yes, but the majority of the volume (~ 70-90%) is removed by OSN-2. If you are doing a fractional distillation afterwards, you can skip the evaporation and take out the ethanol during the initial stages of the fractional distillation.
  • What happens to Terpenes?
    There are a range of Terpenes. It depends on their molecular weight, shape and structure. We don’t have specific data, but our guess would be that 50-60% of higher MW terpenes end up with the CBD and the rest in the permeate with ethanol.
  • Can I recycle the ethanol from OSN-2 and wouldn’t terpenes build up?
    The permeate from OSN-2 can be recycled back to extraction stage and/or the diafiltration stage of OSN-1. Terpenes would build up but after a few batches, the OSN-2 permeate can be disposed (you will have to track for yourself as to when to do that).
  • How about the color / chlorophyll?
    Our estimates are that 70-80% of the color (Chlorophyll, Carotenoids etc.) are removed by OSN-1. However, as Chlorophyll is a linear molecule, some of it permeates along. Most of our customers are happy with the color removal with OSN-1.
  • Can your membranes remediate (remove) pesticides?
    Again, we do not have specific data and there are pesticides of different MW and structures. From some of the data we have seen, we believe that 60-70% of pesticides are removed.
  • Can your membranes remediate (remove) THC?
    THC and CBD have the same molecular weight. Our membranes are not able to separate THC from CBD.
  • What happens to the waxes / lipids taken out by OSN-1?
    The waxes and lipids end up as a concentrated solution in the feed tank to the OSN-1 unit. They can be discharged at the end of the process and treated in the same way as you are currently treating the waxes/lipids collected after the winterization step.
  • What is the overall yield that I can expect?
    At least 90% overall yield.
  • What is the lifetime of the membrane? How often does it have to be replaced?
    One year is our nominal estimate for cost/benefit analysis purposes. In various natural oil / essential oil applications, we have seen our membrane lifetimes to be 2-3 years. OSN-1 membrane is a silicone membrane and, consequently, it does not foul readily. As it is taking out the bulk of the potentially fouling materials, such as waxes, fats and lipids, we would expect the OSN-2 life to be enhanced by having to process fairly clean solutions.
  • What kind of prefiltration is required for the OSN membrane?
    20-30 micron pre-filter would be recommended. It is usually a standard practice to have this in the commercial nanofiltration skids.
  • Can the membrane be cleaned? What is the process?
    For most applications we recommend flushing with the process solvent at 10°C higher temperature than normal processing temperature (i.e. 10°C above ambient).
  • I’ve seen that aqueous membranes can foul quickly. Do the OSN membranes have the same problem?
    Our OSN-1 membrane is a silicone membrane and is not prone to fouling. Biofouling is less prevalent in OSN processes as mostly solvent processing is being used.
  • I have concerns about leaching from your membrane. Any data you can share?
    We have data showing non-detect levels of leachables and extractables. One of the actions recommended would be to initially flush the membranes with the process solvent and carry out the analysis on the permeate and retentate to satisfy yourself of the absence of any extractables and leachables.
  • Does your membrane’s flux decrease over time, like other membranes I have used? If so, what is the expected rate?
    All membranes show this behavior. However, as mentioned earlier, the membranes would have a nominal life of about 1 year and any decline in flux would be minimal during this period.
  • Does the pore size of your membranes change with increasing temperature?
    Generally the rejection is lower as temperature goes higher. However, for all practical purposes the change in rejection is fairly minor.
  • Can I backflush the membrane with N2 gas to clean it?
    We do not recommend any backflushing
  • How can I evaluate OSN technology?
    You can rent a lab unit (MCXF Unit) from Evonik or its partners to carry out initial feasibility studies. You can, if you wish, go directly to a pilot unit – this can also be leased from Evonik or its partners .
  • Can I get an idea of the costs?
  • Does Evonik build the full system skid?
    No. Evonik only makes the membrane modules. Evonik will put you in contact with suitable OEMs (skid builders) for the skid.
  • What is the price of the 8” modules?
  • What is the lead time for the membrane modules?
    If the modules are in stock, it is 6-8 weeks from the time of receipt of PO.
  • Do we buy membranes directly from you or through the OEM?
    Both options are possible.