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Active membrane of NanoFiltration (NF) and UltraFiltration (UF) for better productivity



In recent years, much effort has gone into manufacturing highly efficient membranes for industrial filtration and separation processes. Due to the unparalleled physical and chemical structures of nanomaterials, these have been used for the construction of nanofiltration (NF) and ultrafiltration (UF) membranes. When customers are in a process requiring different molecular weight limits (MWCO), they have to purchase many membranes. The present invention solves this problem by providing a single reusable polymeric membrane offering an adjustable MWCO.


The invention, a cellulose nanocrystal (CNC) membrane with adjustable pore size, aims to replace certain NF and UF membranes currently available on the market in order to offer flexibility to industry in their processes. Depending on process requirements, the end user will be able to actively control the pore size of this smart membrane, down to a few nanometers (nm), by simply bubbling CO2 and N2 through an aqueous solution. This active control allows the adjustment of the level of filtration and the flow rate. In addition, it reduces maintenance costs: since the end user can open the pores to clean the filter and then close them to reuse it as if it were brand new.


First switchable NF-UF membrane on the market.

  • Improved performance:

    • Switchability/active pore size control: control over the opening and closing of pores.

      • NMWCO range: 5,000 to 300,000 Da.

      • Nominal pore size range: 3 nm to 100 nm.

      • Switchability of the pore size: + -50% (ex: for a 10 nm membrane, it would have a pore size ranging from 5 to 15 nm).

    • Two “simple” stimuli for control: either by bubbling CO2 and N2 through the process fluid, or by changing the pH.

    • Accuracy/Repeatability of pore size adjustment: down to the nanometer.

    • Fast response to gas: MWCO adjustment in seconds.

    • Good pressure resistance (P): like standard membranes.

    • Good temperature resistance: 0-40°C, more than 40°C if P? 2 bar).

    • Good chemical compatibility: CNC is a bipolymer and can withstand various aqueous solutions. Functionalized CNC is hydrophilic after CO2 sparging and hydrophobic after N 2 sparging: allows it to be used for oil-and-grease-free (FOG) processes.

  • Economic :

    • for the Membrane Manufacturer:

      • Simple production method.

      • Low amount of active material needed to manufacture the membrane (~ 9gr/m2) and competitive cost of CNC material.

    • for the End User:

      • Use of simple/economic stimuli (CO2 and N2).

      • Increased operational flexibility and reduced maintenance costs:

        • Reduced the number of membranes to acquire.

        • Reusable: easy to wash/remove contaminations.

        • Robust and long operating time.

  • Ecological: energy-efficient process and excellent way to recover CO2. In addition, CNC is an abundant and renewable raw material.


Switchable nano-filtration and ultra-filtration and/or flow control, in different sectors:

  • Medical: hemodialysis, sterilization.

  • Industrial processes:  high quality/ultrapure feed water, recovery/recycling of process water.

  • Food and beverages: concentration, clarification, fractionation.

  • Pretreatment of drinking water and seawater: clarification, pretreatment by reverse osmosis (RO) and reverse electrodialysis (EDR) processes.

  • Biopharmaceutical:  laboratory equipment for centrifugation/separation.

  • Wastewater treatment: domestic/municipal/agricultural/industrial/marine/naval, membrane bioreactors (MBR), oil and grease free (FOG) processes, removal of endocrine disruptors (EDCs).

Usable for various liquids (compatible with cellulose), but pore size switching occurs when the pH is between 6 and 10. Outside this pH range, the membrane is used as a standard membrane.


Provisional patent pending 62/779,120

Operating license available

Project Director: Josianne Vigneault

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