Iron-functionalized alginate for phosphate and other contaminant removal and recovery from aqueous solutions
A biodegradable iron-crosslinked alginate is useful as a remediation agent for environmental contaminants such as phosphate. When charged with phosphate, or other nutrients, the iron-functionalized alginate can be used as an agricultural fertilizer.
1. A biodegradable material comprising iron-functionalized alginate, wherein the iron-functionalized alginate is prepared by the process of:
reacting a source of FeCl 2 with sodium alginate to yield an iron-functionalized alginate bead; and
hardening the iron-functionalized alginate bead in FeCl 2 solution.
2. The biodegradable material of claim 1 wherein the iron-functionalized alginate is Fe(II)-functionalized alginate.
3. The biodegradable material of claim 1 wherein the bead comprises an entrapped nanoparticle.
4. The biodegradable material of claim 1 further comprising phosphorous-containing compound.
5. The biodegradable material of claim 1 further comprising a selenium containing compound.
6. A method for making the biodegradable material of claim 1 , the method comprising:
reacting a source of FeCl 2 with sodium alginate to yield an iron-functionalized alginate bead; and
hardening the iron-functionalized alginate bead in FeCl 2 solution.
7. A method for removing a contaminant from an aqueous medium comprising:
contacting the aqueous medium with the biodegradable material of claim 1 under conditions and for a time effective to sorb the contaminant.
8. The method of claim 7 wherein the contaminant comprises a phosphorous containing compound or a selenium containing compound.
9. The method of claim 8 wherein the contaminant comprises orthophosphate (PO 4 3 ), hydrogen phosphate (HPO 4 2− ), dihydrogen phosphate, (H 2 PO 4 − ), magnesium ammonium phosphate (MgNH 4 PO 4 .6H 2 O, struvite), hydroxyapatite, a polyphosphate, an organic phosphate, a selenate, Se(VI), SeO 4 −2 , a selenite, Se(IV), HSeO 3 , elemental selenium, a selenide, (Se-II), Se 2− , HSe − , or any combination thereof.
10. The method of claim 7 wherein the aqueous medium is a eutrophic lake, municipal and industrial wastewater, agricultural runoff, effluent from water or sewer treatment plants, acid mine drainage, sludge, groundwater, a reservoir, well water, a marsh, swamp, a bay, an estuary, a river, a stream, an aquifer, a tidal or intertidal area, a sea or an ocean.
11. The method of claim 7 wherein the pH of the aqueous environment is higher than 7.5.
12. The method of claim 7 wherein the biodegradable material is disposed within a stationary treatment medium.
13. The method of claim 12 wherein the stationary treatment medium comprises a permeable reactive barrier, a slurry wall, a filtration bed, or a filter.
14. The method of claim 7 further comprising:
collecting the used biodegradable material, wherein the used biodegradable material comprises a sorbed contaminant.
15. The method of claim 7 further comprising
applying the used biodegradable material to soil as a fertilizer, wherein the used biodegradable material comprises a sorbed contaminant, and wherein the sorbed contaminant comprises a nutrient.
16. The method of claim 15 wherein the nutrient comprises a phosphorous containing compound, a selenium containing compound, or a combination thereof.
17. The method of claim 7 , wherein the aqueous medium comprises surface water or groundwater, and wherein the contaminant comprises arsenic.
18. The method of claim 7 wherein the aqueous medium comprises an aquifer or well water.
19. A method for making a fertilizer comprising:
identifying an aqueous medium comprising a nutrient comprising phosphorus-containing compound or a selenium-containing compound, or both;
contacting the aqueous medium with the biodegradable material of claim 1 under conditions and for a time effective to sorb the nutrient onto the biodegradable material to yield a charged biodegradable material; and
incorporating the charged biodegradable material into a fertilizer composition.