Converting acrylic fibers to amidoxime-carboxylate containing polymer adsorbents for sequestering uranium and other elements from water
A fiber comprising a carbon chain backbone and amidoxime, carboxylate, and nitrile pendant groups. The fiber may be used for removing uranium from seawater and toxic metals from drinking water.
1. A method of removing uranium from seawater comprising contacting seawater with a fiber comprising a polymer having a structure comprising:
wherein R is an alkyl, a substituted alkyl, a cycloalkyl, a heterocycloalkyl, an aryl, or a heteroaryl group; and n is 100 to 10,000.
2. The method of claim 1 , wherein uranium is absorbed onto the fiber and the method further comprises removing the absorbed uranium from the fiber.
3. The method of claim 1 , wherein the fiber preferentially adsorbs uranium relative to vanadium.
4. The method of claim 1 , wherein the fiber has a V/U adsorption weight ratio of 2:1 to 1:2.
5. The method of claim 1 , wherein the fiber further comprises at least one carboxylate cation selected from Na + , K + , Cs + , Ca ++ , Mg ++ , and NH 4 + .
6. The method of claim 1 , wherein the fiber is made by a method comprising:
subjecting an acrylic, polyacrylonitrile, and/or polyacrylonitrile copolymer fiber to amidoximation under conditions sufficient for converting a portion of the nitrile pendant groups of the acrylic, polyacrylonitrile, and/or polyacrylonitrile copolymer fiber into amidoxime pendant groups resulting in an intermediate product; and
subjecting the intermediate product to carboxylation under conditions sufficient for converting a portion of the remaining nitrile pendant groups into carboxylate pendant groups.
7. The method of claim 1 , wherein R is methyl, ethyl, propyl, isopropyl, butyl, iso-butyl, sec-butyl, pentyl, 3-pentyl, or hexyl.
8. The method of claim 1 , wherein n is 1000 to 5000.
9. The method of claim 1 , wherein the fiber further comprises a Na + carboxylate cation.
10. The method of claim 9 , wherein R is methyl, ethyl, propyl, isopropyl, butyl, iso-butyl, sec-butyl, pentyl, 3-pentyl, or hexyl.
11. The method of claim 9 , wherein uranium is absorbed onto the fiber and the method further comprises removing the absorbed uranium from the fiber.
12. The method of claim 11 , wherein the fiber is in a form of a monofilament, a multifilament yarn, or a fabric.
13. The method of claim 9 , wherein the fiber is in a form of a monofilament, a multifilament yarn, or a fabric.
14. The method of claim 1 , wherein the fiber is in a form of a monofilament, a multifilament yarn, or a fabric.
15. The method of claim 1 , wherein the fiber has a diameter of 5 to 200 μm.