Process for simultaneous removal of hydrogen sulfide and heavy metals

Patent metadata

Field	Value
Publication number	US-12415726-B2
Application number	US-202217961318-A
Country	US
Kind code	B2
Filing date	Oct 6, 2022
Priority date	Oct 6, 2022
Publication date	Sep 16, 2025
Grant date	Sep 16, 2025

Abstract

A process for simultaneous removal of hydrogen sulfide (H 2 S) and heavy metals from mixture includes charging a contaminated aqueous composition containing heavy metal ions to a reactor. The process also includes passing a H 2 S-containing gas composition via a plurality of gas spargers through the contaminated aqueous composition present in the reactor to form a H 2 S-containing contaminated aqueous composition and a purified gas composition. The process further includes reacting the H 2 S from the H 2 S-containing contaminated aqueous composition with the heavy metal ions in the H 2 S-containing contaminated aqueous composition to form a metal sulfide precipitate in a metal-sulfide-containing contaminated aqueous composition. In addition, the process includes at least partially introducing the metal-sulfide-containing contaminated aqueous composition to a solid-liquid separator and removing the metal sulfide precipitate from the metal-sulfide-containing contaminated aqueous composition to form a purified aqueous composition.

First claim

The invention claimed is:

1. A process for simultaneous removal of hydrogen sulfide (H 2 S) and heavy metals from mixture, comprising:
charging a contaminated aqueous composition containing heavy metal ions to a reactor;
passing a H 2 S-containing gas composition via a plurality of gas spargers through the contaminated aqueous composition present in the reactor to form a H 2 S-containing contaminated aqueous composition and a purified gas composition;
reacting the H 2 S from the H 2 S-containing contaminated aqueous composition with the heavy metal ions in the H 2 S-containing contaminated aqueous composition to form a metal sulfide precipitate in a metal-sulfide-containing contaminated aqueous composition;
at least partially introducing the metal-sulfide-containing contaminated aqueous composition to a solid-liquid separator;
removing the metal sulfide precipitate from the metal-sulfide-containing contaminated aqueous composition to form a purified aqueous composition;
wherein the plurality of gas spargers is within the body of the contaminated aqueous composition to distribute the gas composition in the form of bubbles and is adjacent to a lower end of the reactor;
wherein the reactor is in fluid communication with the solid-liquid separator; and
wherein the H 2 S-containing gas composition is introduced to the reactor at a rate of 4 to 120 milliliters per minute (mL/min) per milligram of the heavy metal ions in the contaminated aqueous composition.

2. The process of claim 1 , wherein the heavy metal ions are at least one selected from the group consisting of chromium (Cr) ions, copper (Cu) ions, lead (Pb) ions, arsenic (As) ions, cadmium (Cd) ions, mercury (Hg) ions, aluminum (Al) ions, uranium (U) ions, strontium (Sr) ions, thallium (Tl) ions, zinc (Zn) ions, molybdenum (Mo) ions, tungsten (W) ions, manganese (Mn) ions, vanadium (V) ions, iron (Fe) ions, cobalt (Co) ions, and nickel (Ni) ions.

3. The process of claim 2 , wherein the Hg(II) ions are present in the contaminated aqueous composition at a concentration in a range of 0.1 to 1 mg/mL and the contaminated aqueous composition is in contact with the H 2 S-containing gas composition at a rate of 92 mL/min in the bubble column reactor, having a saturation time of 10 to 200 minutes, wherein the H 2 S-containing gas composition comprises 100 ppmv of H 2 S.

4. The process of claim 1 , wherein the H 2 S-containing gas composition is passed via four or more gas spargers through the contaminated aqueous composition present in the reactor, wherein each of the gas spargers has a colander aqueous structure with an average pore size in the range of about 1 μm to about 10 mm, and the four or more gas spargers are arranged in a helical shape in four quadrants of the reactor with each quadrant containing at least one gas sparger.

5. The process of claim 1 , wherein each of the spargers of the plurality of gas spargers have:
a first edge and a second edge;
a ratio of a length of each of the spargers of the plurality of gas spargers to a diameter of the reactor in a range of 1:20 to 1:5;
wherein the length of each of the spargers of the plurality of gas spargers is a vertical distance measured between the first edge and the second edge;
wherein the plurality of gas spargers are arranged with respect to one another in a helical pattern;
a vertical distance between the center of any two adjacent helically arranged gas spargers is in a range of 100% to 400% of the outer diameter of the helical pattern; and
a horizontal distance between the center of any two adjacent helically arranged gas spargers is in a range of 50% to 200% of the length of each of the spargers of the plurality of gas spargers.

6. The process of claim 1 , wherein the contaminated aqueous composition comprises at least one liquid selected from the group consisting of tap water, ground water, distilled water, deionized water, saltwater, hard water, fresh water, and wastewater.

7. The process of claim 1 , wherein the contaminated aqueous composition comprises at least one anionic species selected from nitrate, nitrite, sulfate, phosphate, fluoride, bromide, hydroxide, and chloride.

8. The process of claim 1 , wherein the heavy metal ions are mixed-metal ions in the form of a hydroxide salt selected from the group consisting of zinc-iron-aluminum (ZaFeAl) hydroxide, manganese-iron-aluminum (MnFeAl) hydroxide, cobalt-iron-aluminum (CoFeAl) hydroxide, and copper-iron aluminum hydroxide (CuFeAl), where the hydroxide salt of mixed-metal ions is supported on at least one support selected from the group consisting of a graphene, a graphene oxide, a reduced graphene oxide, an alumina, a carbon nanotube, an activated carbon, a metal organic framework (MOF), a zeolitic imidazolate framework (ZIF), and a covalent organic polymer (COP).

9. The process of claim 1 , wherein the reactor is a bubble column reactor in the form of a vertical cylindrical reactor containing at least one propeller agitator disposed therein, wherein the vertical cylindrical reactor has a bottom portion, a vertically oriented cylindrical body portion and a top portion, wherein the bottom portion is cone shaped or pyramidal, wherein a plurality of recirculation tubes fluidly connects the bottom portion of the vertical cylindrical reactor with the body portion of the vertical cylindrical reactor.

10. The process of claim 9 , wherein the reactor further comprises at least one reactor selected from the group consisting of a packed bed reactor and a slurry reactor.

11. The process of claim 9 , wherein the vertically oriented cylindrical body portion of the reactor is fluidly connected to a solid-liquid separator, wherein the solid-liquid separator is fluidly connected to a mixing tank, wherein the mixing tank is fluidly connected to an electrochemical cell containing an anode and a cathode, wherein the electrochemical cell is fluidly connected to a recovery unit.

12. The process of claim 1 , wherein the H 2 S-containing gas composition is natural gas.

13. The process of claim 12 , wherein the H 2 S-containing gas composition further comprises at least one gas selected from the group consisting of nitrogen, argon, methane, ethane, ethylene, propylene, propane, butane, butene, butadiene, and isobutylene.

14. The process of claim 1 , wherein the H 2 S is present in the H 2 S-containing gas composition at s concentration in a range of 10 to 200 parts per million by volume (ppmv) based on a total volume of the H 2 S-containing gas composition.

15. The process of claim 1 , wherein the heavy metal ions are present in the contaminated aqueous composition at a concentration in a range of 0.05 to 15 milligrams per milliliter (mg/mL).

16. The process of claim 1 , wherein during the passing and reacting the contaminated aqueous composition is in contact with the H 2 S-containing gas composition at a temperature in a range of from 15 to 40° C. and under a pressure of 0.9 to 1.2 bar.

17. The process of claim 1 , further comprising:
electrolyzing the purified aqueous composition to form hydrogen gas by:
at least partially introducing the purified aqueous composition to a mixing tank under continuous agitation;
charging an electrolyte solution to the mixing tank and mixing to form an electrolyte containing aqueous composition;
at least partially introducing the electrolyte containing aqueous composition to an electrochemical cell containing an anode and a cathode;
wherein both electrodes are at least partially immersed in the electrolyte containing aqueous composition;
applying a potential between the anode and cathode

Assignees

• Univ King Fahd Pet & Minerals

Inventors

• Onaizi Sagheer A

Classifications

• B01D53/8606

  only one sulfur compound other than sulfur oxides or hydrogen sulfide · CPC title

• C01P2006/80

  Compositional purity · CPC title

• C01B17/162

  from elemental sulfur and hydrogen · CPC title

• B01D2257/308

  Carbonoxysulfide COS · CPC title

• B01D53/485

  containing only one sulfur compound other than sulfur oxides or hydrogen sulfide · CPC title