Purification of carbon nanotubes based on the chemistry of fenton's reagent

1. A method comprising the steps of:

a) preparing an aqueous slurry of impure carbon nanotube (CNT) material, wherein the impure CNT material comprises Fe impurities and CNTs;

b) adding a non-oxidizing mineral acid to the aqueous slurry to adjust and maintain pH of said aqueous slurry between about 1 and about 3, thereby providing an acidic slurry;

c) adding hydrogen peroxide to the acidic slurry to form an oxidative slurry, wherein at least some of the Fe impurities are converted into Fe 2+ , and wherein Fe 2+ present in the oxidative slurry catalyzes a production of hydroxyl radicals; and

d) utilizing the hydroxyl radicals to purify the CNT material and provide purified CNTs.

2. The method of claim 1 , wherein the CNTs in the impure CNT material are selected from the group consisting of single-wall carbon nanotubes, double-wall carbon nanotubes, multi-wall carbon nanotubes, and combinations thereof.

3. The method of claim 1 , further comprising seeding the aqueous slurry with catalytic Fe 2+ by adding an iron salt.

4. The method of claim 1 , further comprising stirring the oxidative slurry to facilitate purification.

5. The method of claim 1 , further comprising a step of allowing phase separation to occur such that the purified CNTs are separated from other oxidative slurry components.

6. The method of claim 5 , further comprising a step of decanting to additionally separate the purified CNTs from other oxidative slurry components.

7. The method of claim 1 , further comprising a repetition of at least one of the steps of which the method is comprised.

8. The method of claim 1 , wherein the non-oxidizing mineral acid is hydrochloric acid.

9. A method comprising the steps of:

a) preparing an aqueous slurry of impure carbon nanotube (CNT) material, wherein the impure CNT material comprises CNTs;

b) establishing a source of Fe 2+ ions in the aqueous slurry to provide a catalytic slurry;

c) adding a non-oxidizing mineral acid to the catalytic slurry to provide an acidic slurry;

d) adding hydrogen peroxide to the acidic slurry to provide an oxidative slurry with a pH between about 1 and about 3, wherein the Fe 2+ ions catalyze a production of hydroxyl radicals; and

e) utilizing the hydroxyl radicals in the oxidative slurry to purify the CNT material and provide purified CNTs.

10. The method of claim 9 , wherein the CNTs in the impure CNT material are selected from the group consisting of single-wall carbon nanotubes, double-wall carbon nanotubes, multi-wall carbon nanotubes, and combinations thereof.

11. The method of claim 9 , wherein the source of Fe 2+ ions in the aqueous slurry is established by adding an iron salt.

12. The method of claim 9 , further comprising stirring the oxidative slurry to facilitate purification.

13. The method of claim 9 , further comprising a step of allowing phase separation to occur such that the purified CNTs are separated from other oxidative slurry components.

14. The method of claim 13 , further comprising a step of decanting to additionally separate the purified CNTs from other oxidative slurry components.

15. The method of claim 9 , further comprising a repetition of at least one of the steps of which the method is comprised.

16. The method of claim 9 , wherein the non-oxidizing mineral acid is hydrochloric acid.

17. A method comprising the steps of:

a) preparing an aqueous slurry of impure carbon nanotube (CNT) material, wherein the impure CNT material comprises small-diameter carbon nanotubes;

b) establishing a source of Fe 2+ ions in the aqueous slurry to provide a catalytic slurry;

c) adding a non-oxidizing mineral acid to the catalytic slurry to provide an acidic slurry;

d) adding hydrogen peroxide to the acidic slurry to provide an oxidative slurry with a pH between about 1 and about 3, wherein the Fe 2+ ions catalyze a production of hydroxyl radicals; and

e) utilizing the hydroxyl radicals in the oxidative slurry to purify the CNT material and provide purified CNTs.

18. The method of claim 17 , wherein the source of Fe 2+ ions in the aqueous slurry is established by adding an iron salt.

19. The method of claim 17 , further comprising stirring the oxidative slurry to facilitate purification.

20. The method of claim 17 , further comprising a step of allowing phase separation to occur such that the purified CNTs are separated from other oxidative slurry components.

21. The method of claim 20 , further comprising a step of decanting to additionally separate the purified CNTs from other oxidative slurry components.

22. The method of claim 17 , further comprising a repetition of at least one of the steps of which the method is comprised.

23. The method of claim 17 , wherein the non-oxidizing mineral acid is hydrochloric acid.

24. A method comprising the steps of:

a) preparing an aqueous slurry of impure carbon nanotube (CNT) material, wherein the impure CNT material comprises CNTs;

b) establishing a source of metal ions in the aqueous slurry to provide a catalytic slurry;

c) adding a non-oxidizing mineral acid to the catalytic slurry to provide an acidic slurry;

d) adding hydrogen peroxide to the acidic slurry to provide an oxidative slurry with a pH between about 1 and about 3, wherein the metal ions catalyze a production of hydroxyl radicals; and

e) utilizing the hydroxyl radicals in the oxidative slurry to purify the CNT material and provide purified CNTs.

25. The method of claim 24 , wherein the metal ions are selected from the group consisting of Cu(I), Ti(III), Cr(II), Co(II), Mn(III), and combinations thereof.

26. The method of claim 24 , wherein the non-oxidizing mineral acid is hydrochloric acid.