Particulate medium prepared from partially decomposed organic matter for selective sorption between competing metal ions in aqueous solutions

Patent metadata

Field	Value
Publication number	US-10173213-B2
Application number	US-201615052403-A
Country	US
Kind code	B2
Filing date	Feb 24, 2016
Priority date	Mar 15, 2013
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

A process for the preparation of a granulated or pelletized sorption medium from a partially decomposed organic material like peat, followed by low-temperature thermal activation of the sorption medium to produce a high degree of granule or pellet hardness balanced against an efficacious level of ion-exchange and adsorption capacity, followed by chemical treatment of the sorption material via a preselected solution of soluble salts (called “APTsorb II*M”) for use in a wastewater treatment process where competing toxic metal cations are present in the wastewater is provided by this invention. Depending upon the M + cations contributed to the peat granule sorption activity sites by the preselected salt used in the salt solution treatment step, the granules exhibit a selectivity α of a first type of more-toxic metal cations (such as cadmium, lead, copper, or other metals at high concentrations) over a second type of less-toxic metal cations of (such as zinc, aluminum, or iron) in the wastewater; greater adsorption activity for the first type of more-toxic metal cations; and greater breakthrough capacity for the first type of more-toxic metal cations. This allows the end user to target the more-toxic metals for adsorption by the sorption medium containing the cations contributed by the preselected solution of soluble salts.

First claim

We claim:

1. A process for the production from partially decomposed organic matter of a sorption media for use in the treatment of aqueous solutions comprising at least one more-toxic metal and at least one less-toxic metal to remove at least one type of aqueous contaminant therein, comprising the steps of:
(a) supplying an amount of the partially decomposed moisture-bearing organic matter to a granulating machine;
(b) granulating the partially decomposed organic matter after introducing a synergistic interactive agent;
(c) drying the granules;
(d) thermally activating the granules without chemical activation using an activation heat medium at a temperature of about 175-287° C., wherein the granule has a Ball-Pan Hardness number of about 75%-400% and is suitable for sorption of the aqueous contaminant found in the aqueous solution; and
(e) chemically treating the thermally-activated granule with a salt solution preselected in the form of a soluble salt compound having a cation constituent and an anion constituent, wherein:
(i) the cation constituent of the salt solution is selected from the group consisting of any 1 + or 2 + cation of, without limitation, ammonium (NH 4 + ), ammonium groups (NR 4 + ), sodium, potassium, lithium, cesium, beryllium, magnesium, calcium, barium, manganese, copper, zinc, strontium, and iron;
(ii) the anion constituent of the salt solution is selected from the group consisting of SO 4 2− , HSO 4 − , SO 3 2− , NO 3 − , NO 2 − , PO 4 3− , HPO 4 2− , H 2 PO 4 − , Cl − , I − , Br − , F − , HCOO − , CH 3 COO − , C 2 H 5 COO − , C 3 H 7 COO − , C 4 H 9 COO − , ClO 4 − , HCO 3 − , or CO 3 2− ;
(iii) the chemical treatment of the granule with the salt solution places the selected cations provided by the cation constituent of the salt solution onto the active adsorption sites in the granule;

(f) wherein the presence of the cations of the cation constituent of the salt solution on the active sites of the granule interacts with the synergistic interactive agent to alter the coefficient that defines the solution equilibrium of the aqueous solution to influence the adsorption capacity of the thermally-activated and chemically-treated sorption medium granules to selectively adsorb the more-toxic metal cations at the expense of the less-toxic metal contaminant cations, and increase the adsorption activity of the granules for the more-toxic metal cations, so that the granules can sorb the more-toxic metal cations from the treated aqueous solution, while leaving a substantial portion of the less-toxic metal contaminant cations in the aqueous solution.

2. The process of claim 1 , wherein the synergistic interactive agent is calcium carbonate or another alkaline earth metal carbonate compound.

3. The process of claim 1 , wherein the synergistic interactive agent is a non-water soluble salt made out of anions of polyprotic acids selected from the group consisting of PO 4 3− , HPO 4 2− , H 2 PO4 − , SO 4 2− , HSO 4 − , C 2 O 4 2− (oxalic acid), HC 2 O 4 − , C 6 H 8 O 4 2− (adipic acid), C 6 H 9 O 4 − (adipic acid), C 6 H 4 (COO) 2 2− (phthalic acid), and C 6 H 4 C 2 O 4 H − , and cations of an alkaline earth metal cations selected from the group consisting of Ca 2+ , Mg 2+ , Be 2+ , Ba 2+ , and Sr 2+ .

4. The process of claim 1 , wherein for an aqueous solution containing cadmium as the more-toxic metal cations and zinc as the less-toxic metal cations, the selectivity of the granule for the cadmium cations over the zinc cations is 1.62<α≤3.00 when the initial influent concentration is C Cd =30 ppm and C Zn =30 ppm.

5. The process of claim 1 , wherein for an aqueous solution containing cadmium as the more-toxic metal cations and zinc as the less-toxic metal cations, the cadmium adsorption activity of the granule, as measured by cadmium concentration in the aqueous solution, is 1.02 ppm<C Cd ≤0.209 ppm when the initial influent concentration is C Cd =30 ppm and C Zn =30 ppm.

6. The process of claim 1 , wherein for an aqueous solution containing cadmium as the more-toxic metal cations and zinc as the less-toxic metal cations, the zinc adsorption activity of the granule, as measured by zinc concentration in the aqueous solution, is 1.54 ppm<CZn≤0.387 ppm when the initial influent concentration is C Cd =30 ppm and C Zn =30 ppm.

7. The process of claim 1 , wherein the granule used within an aqueous solution treatment further comprises a greater breakthrough capacity for the more-toxic metal cations.

8. The process of claim 7 , wherein for an aqueous solution containing cadmium as the more-toxic metal cations and zinc as the less-toxic metal cations, the breakthrough capacity for cadmium cations of the granule is 2.99-3.04 mg/g Cd at 50 ppb at 0.1 m/hr flow velocity when the initial influent concentration is C Cd =30 ppm and C Zn =30 ppm.

9. The process of claim 7 , wherein the pre-selected soluble salt compound for the salt solution used in the chemical treatment step for the production of the sorption medium results in an improved breakthrough capacity for the more-toxic metal contaminant up to 21.32 mg/g at 50 ppb of the major toxic metal.

10. The process of claim 1 , wherein the more-toxic metal contaminant found in the aqueous solution is selected from the group consisting of a chemical element or compound that poses a health risk to humans or animals, or is otherwise subject to environmental laws or regulations in the form of heavy metals comprising arsenic, lead, mercury, cadmium, manganese, iron, nickel, copper, molybdenum, cobalt, chromium, palladium, stannum, or aluminum; radioactive materials like cesium or various isotopes of uranium; selenium and boron.

11. The process of claim 1 , wherein the less-toxic metal contaminant found in the aqueous solution is selected from the group consisting of a chemical element or compound found in an aqueous solution that does not necessarily pose a health risk to humans or animals or is otherwise subject to environmental laws or regulations in the form of metals comprising magnesium, beryllium, strontium, barium, calcium, manganese, copper, zinc, iron, potassium, lithium, ammonium, and ammonium groups.

12. The process of claim 1 , wherein the partially decomposed organic matter is selected from the group consisting of compost media, livestock manure, sewage sludge, and combinations thereof.

13. The process of claim 12 , wherein the partially decomposed organic matter is compost media.

14. The process of claim 13 , wherein the compost media is selected from the group consisting of leaf compost media, peat, plant by-products, and combinations thereof.

15. The process of claim 1 , wherein the aqueous solution comprises a water-based solution containing an environmental impurity as a solute produced by manufacturing, agricultural, or mining industries, or population communities.

16. The process of claim 1 , wherein the granule temperature during the drying step is conducted at a temperature of about 80-400° C.

17. The process of claim 16 , wherein the moisture level of peat granules is reduced within the drying step from about 40% wt. to about 10-14% wt.

18. The process of claim 1 , wherein the granules are thermally activated in an inert environment.

19. The process of claim 1 wherein the activation heat medium comprises steam or carbon dioxide, nitrogen or other inert media, or combinations thereof at a temperature of about 175-287° C. until the desired level of hardness and activation is achieved.

20. The process of claim 1 , w

Assignees

• American Peat Tech Llc
• Univ Minnesota

Inventors

• Kolomitsyn Igor V
• Jones Peggy Wallgren
• Green Douglas A

Classifications

• C02F2001/425

  using cation exchangers · CPC title

• B01J20/3078

  Thermal treatment, e.g. calcining or pyrolizing · CPC title

• C02F1/286

  using natural organic sorbents or derivatives thereof · CPC title

• B01J20/3085

  Chemical treatments not covered by groups B01J20/3007 - B01J20/3078 · CPC title

• B01J20/3021

  Milling, crushing or grinding · CPC title