Low pressure reverse osmosis and nanofiltration membranes and method for the production thereof
AssigneeHydranautics
InventorJohn Edward Tomaschke
Life of this patent
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Abstract
Novel low pressure reverse osmosis and nanofiltration membranes and a process for their preparation are disclosed. Polyamide reverse osmosis membranes are contacted with organic sulfonic acid solutions without the need for additional treatment by a rejection enhancing agent. These membranes provide sodium chloride rejections of greater than 20 percent and water fluxes greater than 15 gallons per square foot per day at a test pressure of 75 psi. Optimally treated membranes when tested similarly on 0.2 percent magnesium sulfate provide rejections greater than 95 percent with water fluxes greater than 15 gallons per square foot per day.
Claims11
A composite membrane useful for reverse osmosis or nanofiltration comprising:
- a supportive porous under-structure;
- and
- a top layer consisting of a crosslinked polyamide thin film which is adhered to the upper surface of the porous support structure, said top layer having been contacted with a solution of a C1–C6 alkyl, alkenyl, haloalkyl, haloalkenyl, or hydroxy sulfonic or disulfonic acid compound,
- whereby said membrane has a water flux of at least about 15 gfd and a rejection of at least 20 percent when tested an a 0.05 percent aqueous sodium chloride at 75 psi and 25° C.
Dependencies are inferred from the claim text.