Ultra-violet treatment of membranes and resulting membrane

1. A membrane comprising:

a first outer surface having a plurality of pores in a skin layer;

the plurality of pores having a closed perimeter in the skin layer;

a second outer surface;

a porous supporting layer connecting the first outer surface to the second outer surface; and

wherein the first outer surface comprises a melt-fused skin layer from exposure to ultra-violet light;

wherein the melt-fused skin layer has a depth and the depth extends for 500 nanometers or less; and

wherein the membrane has a throughput capacity expressed as a mass of filtrate weighed after 10 minutes of filtration, and wherein the throughput capacity is between about 100 to 1000 grams.

2. The membrane of claim 1 , wherein the second outer surface has a plurality of pores having a closed perimeter, and wherein the second outer surface comprises a skin layer.

3. The membrane of claims 1 or 2 , wherein the membrane has a log reduction value greater than or equal to 7.

4. The membrane of claims 1, 2, or 3 , wherein the membrane's first outer surface is made from a poly (arylene ether) such as polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, or polysulfone.

5. The membrane of claim 4 , wherein the first outer surface has a yellow tint.

6. The membrane of claim 4 , wherein the first outer surface has a matte sheen.

7. The membrane of claim 4 , wherein a time-of-flight secondary mass spectrometry (TOF-SIMS) analysis of the first outer surface shows degradation species comprising sulfur.

8. The membrane of claims 1, 2, or 3 , wherein the supporting layer comprises a three-dimensional sponge-like network having a separating layer with a plurality of pores and the pores in the separating layer are smaller than the pores in the first outer surface.

9. The membrane of claim 1 , wherein the second surface comprises a plurality of pores in a skin layer; the plurality of pores having a closed perimeter in the skin layer; and wherein the second outer surface comprises a melt-fused skin layer from exposure to ultra-violet light.

10. A method of increasing the pore size in an outer surface of a membrane, the method comprising:

providing a membrane having a first outer surface having a plurality of pores in a skin layer; the plurality of pores having a closed perimeter in the skin layer; and the membrane having a second outer surface and a porous supporting layer connecting the first outer surface to the second outer surface; and

exposing the first outer surface to a pulsed ultra-violet flashlamp radiation, thereby generating a melt-fused skin layer, whereby the pores in the first surface are increased in size after exposure to the pulsed ultra-violet flashlamp radiation;

wherein the membrane, after exposing the first outer surface to the pulsed ultra-violet flashlamp radiation, has a throughput capacity expressed as a mass of filtrate weighed after 10 minutes of filtration, and wherein the throughput capacity is between about 100 to 1000 grams.

11. The method of claim 10 , wherein the membranes first outer surface is made from a poly (arylene ether) such as polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, or polysulfone.

12. The method of claim 11 , wherein the first outer surface comprises polyethersulfone and an energy absorbed by the first outer surface is between about 45 to 440 mJ/cm 2 .

13. The method of claim 10 , wherein the pores have a pore diameter and the pore diameter is increased in size between about 10 to about 100 percent.

14. The method of claim 10 , wherein the first outer surface has a surface porosity and the surface porosity is increased between about 20 to about 200 percent.

15. The method of claim 10 , wherein the throughput capacity of the membrane is increased by at least 20 percent.

16. The method of claim 10 , wherein the membrane has a log reduction of at least 7.

17. The method of claim 10 , wherein a pulse duration for the pulsed ultra-violet flashlamp radiation is between about 2 to about 100 μs.

18. The method of claim 10 , wherein a total energy output of a xenon flashlamp is between about 25 to 200 mJ/cm 2 per pulse.