Double charge composite materials for contaminant removal and methods of making the same
A method for removing a contaminant from a fluid is provided. A positively charged layered double hydroxide is combined with a negatively charged clay material to form adsorption material. The adsorption material is contacted with an aqueous solution containing the contaminant to adsorb the contaminant onto the adsorption material.
1. A method for removing an ionic contaminant from a fluid, comprising:
introducing a solution comprising a material consisting essentially of an anionic layered double hydroxide with a cationic clay material into the fluid to form a flocculant adsorption material having oppositely charged components, the fluid comprising the ionic contaminant; and
absorbing the contaminant onto the flocculant adsorption material;
wherein the anionic layered double hydroxide comprises a crystalline, layered double hydroxide metal complex comprising an interlayer anion; and
wherein the anionic layered double hydroxide has the general formula:
M(II) 1-x M(III) x (OH) 2 (Y/ n ) z H 2 O
wherein 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 interlayer anion;
wherein Y is selected from the group consisting essentially of CO 3 2− , SO 4 2− , PO 4 3− and NO 3− ;
n is the charge of the interlayer anion;
z is a positive number;
M(II) is a divalent metal selected from the group consisting essentially of Co 2+ , Ni 2+ , Zn 2+ , Cu 2+ , Cr 2+ , Mn 2+ , and Fe 2+ ; and
M(III) is a trivalent metal selected from the group consisting essentially of Cr 3+ , Fe 3+ , Sc 3+ , Ti 3+ , V 3+ , Mn 3+ , Co 3+ , Ni 3+ , Rh 3+ , Ru 3+ , and Ir 3+ .
2. The method of claim 1 , wherein the adsorption material includes between about 1 and 50 wt. % of anionic layered double hydroxides.
3. The method of claim 1 , wherein the adsorption material includes between about 10 and 50 wt. % of anionic layered double hydroxides.
4. The method of claim 1 , wherein the ratio of layered double hydroxide to the cationic clay material is a preselected ratio that corresponds to the ionic contaminant.
5. The method of claim 1 , wherein the cationic clay material includes a swelling clay material.
6. The method of claim 1 , wherein the cationic clay material includes a smectite clay material.
7. The method of claim 1 , wherein the cationic clay material includes a montmorillonite clay.
8. The method of claim 1 , wherein the interlayer anion is selected from the group consisting of carbonate, sulfate, phosphate and nitrate anions.
9. The method of claim 1 , wherein the anionic layered double hydroxide and the cationic clay material are physically mixed before being introduced into the fluid to form the flocculant in a repository site or landfill.
10. The method of claim 1 , further comprising:
forming the anionic layered double hydroxide by co-precipitation of a divalent metal M(II) salt solution and a trivalent metal M (III) salt solution at a desired M(II)/M(III) molar ratio upon titration with a basic solution in the presence of the chosen interlayer anion to form the anionic layered double hydroxide;
wherein the anionic layered double hydroxide has the general formula:
M(II) 1-x M(III) x (OH) 2 (Y/ n ) z H 2 O
wherein 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 interlayer anion;
wherein Y is selected from the group consisting essentially of CO 3 2− , SO 4 2− , PO 4 3− and NO 3− ;
n is the charge of the interlayer anion;
z is a positive number;
M(II) is a divalent metal selected from the group consisting essentially of Co 2+ , Ni 2+ , Zn 2+ , Cu 2+ , Cr 2+ , Mn 2+ , and Fe 2+ ; and
M(III) is a trivalent metal selected from the group consisting essentially of Cr 3+ , Fe 3+ , Sc 3+ , Ti 3+ , V 3+ , Mn 3+ , Co 3+ , Ni 3+ , Rh 3+ , Ru 3+ , and Ir 3+ .
11. The method of claim 1 , wherein the flocculant adsorption material is formed in the presence of sand.