Magnetic nanoparticle complex

1. A magnetic nanoparticle complex comprising:

a magnetic nanoparticle; and

a ligand associated with the magnetic nanoparticle, the ligand comprising a functional group capable of combining with an acid component or a conjugate base of the acid component, in an oil;

wherein:

the functional group comprises an ammonium group capable of combining with the conjugate base of the acid component;

a nitrogen atom of the ammonium group is bound with at least one hydrocarbon group; and

the hydrocarbon group is a substituted or unsubstituted C 8 -C 20 alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or aralkyl group.

2. The magnetic nanoparticle complex of claim 1 , wherein the functional group is bound with an anion which can be substituted by the conjugate base of the acid component.

3. The magnetic nanoparticle complex of claim 2 , wherein the anion is a hydroxide ion.

4. The magnetic nanoparticle complex of claim 1 , wherein the ligand comprises at least one carbamate group or at least one dithiocarbamate group.

5. The magnetic nanoparticle complex of claim 1 , wherein the ligand comprises the following structural units:

wherein:

R 1 is a CO 2 − or a CS 2 − group; and

R 2 and R 3 are each independently a hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or aralkyl group;

with the proviso that that R 2 and R 3 are not hydrogen concurrently, and at least one of R 2 and R 3 is a C 8 -C 20 hydrocarbon group.

6. The magnetic nanoparticle complex of claim 5 , wherein the ligand is derived from a compound of Formula I:

wherein n is an integer from 0 to 50, wherein a hydrogen atom of at least one NH group is replaced by a CO 2 − or a CS 2 − group and at least a portion of the hydrogen atoms in the secondary amino groups in the compound of Formula I are substituted by an aminoalkyl group, an aminocycloalkyl group, or an aminoaryl group.

7. A method for refining an oil comprising treating the oil with the magnetic nanoparticle complex according to claim 1 to reduce an amount of an acid component in the oil.

8. The method of claim 7 , wherein the oil is petroleum.

9. The method of claim 7 , wherein the acid component comprises naphthenic acid.

10. The method of claim 7 , further comprising separating the magnetic nanoparticle complex combined with the acid component or the conjugate base of the acid component by applying a magnetic field to a mixture of the oil and the magnetic nanoparticle complex.

11. The method of claim 7 , further comprising regenerating the magnetic nanoparticle complex combined with the acid component or the conjugate base of the acid component.

12. The method of claim 11 , wherein regenerating the magnetic nanoparticle complex comprises treating the magnetic nanoparticle complex combined with the acid component or the conjugate base of the acid component with an excess amount of a base component.

13. The method of claim 12 , wherein the base component comprises a metal hydroxide or an ammonium hydroxide.

14. The method of claim 7 , wherein the method is performed by a continuous process.

15. A magnetic nanoparticle complex comprising:

a magnetic nanoparticle; and

a ligand associated with the magnetic nanoparticle, the ligand comprising a functional group capable of combining with an acid component or a conjugate base of the acid component, in an oil;

wherein the ligand comprises the following structural units:

wherein:

R 1 is a CO 2 − or a CS 2 − group; and

R 2 and R 3 are each independently a hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or aralkyl group;

with the proviso that that R 2 and R 3 are not hydrogen concurrently, and at least one of R 2 and R 3 is a C 8 -C 20 hydrocarbon group.

16. The magnetic nanoparticle complex of claim 15 , wherein the ligand is derived from a compound of Formula I:

wherein n is an integer from 0 to 50, wherein a hydrogen atom of at least one NH group is replaced by a CO 2 − or a CS 2 − group and at least a portion of the hydrogen atoms in the secondary amino groups in the compound of Formula I are substituted by an aminoalkyl group, an aminocycloalkyl group, or an aminoaryl group.

17. A method for refining an oil comprising treating the oil with a magnetic nanoparticle complex to reduce an amount of an acid component in the oil;

wherein:

the magnetic nanoparticle complex comprises:

a magnetic nanoparticle; and

a ligand associated with the magnetic nanoparticle, the ligand comprising a functional group capable of combining with an acid component or a conjugate base of the acid component, in an oil;

wherein the ligand comprises the following structural units:

R 1 is a CO 2 − or a CS 2 − group; and

R 2 and R 3 are each independently a hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, aryl, or aralkyl group;

with the proviso that that R 2 and R 3 are not hydrogen concurrently, and at least one of R 2 and R 3 is a C 8 -C 20 hydrocarbon group.

18. The method of claim 17 , wherein the oil is petroleum.

19. The method of claim 17 , wherein the acid component comprises naphthenic acid.

20. The method of claim 17 , further comprising separating the magnetic nanoparticle complex combined with the acid component or a conjugate base of the acid component by applying a magnetic field to a mixture of the oil and the magnetic nanoparticle complex.

21. The method of claim 17 , further comprising regenerating the magnetic nanoparticle complex combined with the acid component or a conjugate base of the acid component.