Method for absorbing an ion from a fluid

1. A method for absorbing an ion from a fluid, comprising;

dispersing an organic acid of the formula C a H b O c , where a≧7, b>0 and c>0, in water to form an anion surfactant solution;

mixing a divalent-metal cation M(II) containing compound with a trivalent-metal cation M(III) containing compound into said anion surfactant solution to form a precursor solution;

heating said precursor solution to form a solid layered double hydroxide product in solution;

separating said solid layered double hydroxide product from said solution;

calcining said solid layered double hydroxide product to form an absorption material of the formula M(II) x M(III)(OH) 2x+2 (Y/n).zH 2 O, where M(II) is a divalent metal cation, M(III) is a trivalent metal cation, x is a positive number between 1.5 and 12, Y is an anionic surfactant comprising at least 7 carbon atoms, n is a positive integer, and z is a positive number less than 10; and

contacting said absorption material with an aqueous solution containing at least one charged ion, said at least one charged ion selected from the group consisting of lead, arsenic, selenium, and combinations thereof.

2. The method of claim 1 wherein the divalent-metal containing compound comprises a divalent metal selected from Co 2+ , Ni 2+ , Zn 2+ , Mg 2+ , Cu 2+ , Cr 2+ , Mn 2+ , and Fe 2+ .

3. The method of claim 1 wherein the trivalent-metal containing compound comprises a divalent metal selected from Cr 3+ , Al 3+ , Fe 3+ , Sc 3+ , Ti 3+ , V 3+ , Mn 3+ , Co 3+ , Ni 3+ , Rh 3+ , Ru 3+ , and Ir 3+ .

4. The method of claim 1 wherein the organic acid is selected from stearic acid, terephthalic acid, elaidic acid, and oleic acid.

5. The method of claim 1 wherein the absorption material has a surface area of approximately 60 m 2 /g and an average pore size of approximately 20 nm.

6. The method of claim 1 wherein the solid layered double hydroxide product is monolayered.

7. The method of claim 1 wherein the solid layered double hydroxide product is bilayered.

8. A method for absorbing an ion from a fluid, comprising;

dispersing an organic acid selected from the group consisting of stearic acid, terephthalic acid, elaidic acid, and oleic acid in water in the presence of an hydroxide ion to form an anion surfactant solution;

mixing a divalent-metal cation M(II) containing compound with a trivalent-metal cation M(III) containing compound into said anion surfactant solution to form a precursor solution;

heating said precursor solution to form a solid layered double hydroxide product in solution;

separating said solid layered double hydroxide product from said solution;

calcining said solid layered double hydroxide product to form an absorption material of the formula M(II) x M(III)(OH) 2x+2 (Y/n).zH 2 O, where M(II) is a divalent metal cation, M(III) is a trivalent metal cation, x is a positive number between 1.5 and 12, Y is an anionic surfactant comprising at least 7 carbon atoms, n is a positive integer, and z is a positive number less than 10; and

contacting said absorption material with an aqueous solution containing at least one charged ion, said at least one charged ion selected from the group consisting of lead, arsenic, selenium, and combinations thereof.

9. The method of claim 8 wherein the divalent-metal containing compound comprises a compound selected from a Zn-containing compound and a Mg-containing compound.

10. The method of claim 9 wherein the trivalent-metal containing compound is an Al-containing compound.

11. The method of claim 8 wherein the aqueous solution had a pH greater than 6 and less than or equal to 10.

12. The method of claim 8 wherein the solid layered double hydroxide product is monolayered.

13. The method of claim 8 wherein the solid layered double hydroxide product is bilayered.