초록 ▼

A novel water softening membrane and process for making the same is described. The membrane can be prepared by treating a polyamide reverse osmosis membrane with a strong mineral acid followed by treatment with a rejection enhancing agent. The resulting membrane at transmembrane pressures of 50 psi

A novel water softening membrane and process for making the same is described. The membrane can be prepared by treating a polyamide reverse osmosis membrane with a strong mineral acid followed by treatment with a rejection enhancing agent. The resulting membrane at transmembrane pressures of 50 psi can attain a magnesium sulfate rejection with a 0.2 percent aqueous solution of more than 90 percent with a water flux of more than 15 gallons per square foot per day.

대표청구항 ▼

A process comprising making a membrane having properties for enabling water softening, by, (a) contacting a crosslinked polyamide discriminating layer of a reverse osmosis membrane with an aqueous solution of a compatible strong mineral acid; (b) maintaining the membrane in contact with the acid at

A process comprising making a membrane having properties for enabling water softening, by, (a) contacting a crosslinked polyamide discriminating layer of a reverse osmosis membrane with an aqueous solution of a compatible strong mineral acid; (b) maintaining the membrane in contact with the acid at an elevated temperature for a period sufficient to produce a membrane having a flux of at least about 8 gfd and a MgSO4 rejection of at least about 65 percent when tested under reverse osmosis conditions at 50 psi and 25°C. using an aqueous solution of 0.2 weight percent MgSO4; and (c) contacting the membrane from step (b) with a rejection enhancing agent so as to produce a membrane having a MgSO4 rejection of at least about 85 percent.