Composite polyamide membrane having azo content and high acid content
A thin film composite polyamide membrane comprising a porous support and a thin film polyamide layer characterized by possessing: i) an azo (—N═N—) content of from 0.40% to 1.00%, as measured by pyrolysis gas chromatography; and ii) a dissociated carboxylate content of at least 0.40 mol/kg as measured by RBS at pH 9.5.
1. A thin film composite polyamide membrane comprising a porous support and a thin film polyamide layer characterized by possessing:
i) an azo (—N═N—) content of from 0.40% to 1.00%, as measured by pyrolysis gas chromatography; and
ii) a dissociated carboxylate content of at least 0.40 mol/kg as measured by RBS at pH 9.5.
2. The membrane of claim 1 wherein the thin film polyamide layer is further characterized by possessing a dissociated carboxylate content of at least 0.45 mol/kg.
3. The membrane of claim 1 wherein the thin film polyamide layer is further characterized by possessing an azo content of from 0.40% to 0.75%.
4. The membrane of claim 1 wherein the thin film polyamide layer is further characterized by producing a ratio of dimers represented by Formula V and VI from 2.0% to 4.0% upon pyrolysis at 650° C. as measured by GS MS
5. The membrane of claim 4 wherein the thin film polyamide layer is further characterized by producing a ratio the dimers of from 2.6% to 4.0%.
6. The membrane of claim 4 wherein the thin film polyamide layer is further characterized by producing a ratio the dimers of from 2.7% to 4.0%.
7. The membrane of claim 4 wherein the thin film polyamide layer is further characterized by producing a ratio the dimers of from 3.0% to 4.0%.