Systems for catalytically removing oxidized contaminants from a fluid and related methods
The present invention relates to systems and methods for catalytic removal of oxidized contaminants (for example, nitrite, chromate, chlorate, trichloroethene, CFC-11, 4-nonylphenol, RDX, and perfluorooctanoate) from water and wastewater. In some aspects, the catalytic method of removing oxidized contaminants comprises using precious metal nanoparticles as catalysts to reduce the oxidized contaminants.
1 . A method of establishing a catalyst film for long-term removal of oxidized contaminants from a fluid, the method comprising:
providing a non-porous gas transfer membrane, wherein the non-porous gas transfer membrane comprises a gas-phase side and a liquid-phase side;
contacting the liquid-phase side of the non-porous gas transfer membrane with a precious metal medium, the precious metal medium comprising a precious metal salt and a solvent; and
contacting the gas-phase side of the non-porous gas transfer membrane with hydrogen (H 2 ) gas at a sufficient partial pressure to convert at least 90% of the precious metal salt in the precious metal medium to an elemental form in the form of nanoparticles with a mean diameter of less than 5 nm;
wherein the elemental form of the precious metal is deposed on the liquid-phase side of the non-porous gas transfer membrane thereby forming the catalyst film.
2 . The method of claim 1 , wherein the precious metal salt comprises palladium (II).
3 . The method of claim 2 , wherein the precious metal salt further comprises rhodium (III), ruthenium (III), or iridium (IV).
4 . The method of claim 2 , wherein the precious metal salt consists of:
palladium (II),
palladium (II) and rhodium (III),
palladium (II) and ruthenium (III), or
palladium (II) and iridium (IV).
5 . The method of claim 1 , wherein the pH of the precious metal medium is 7±0.5.
6 . The method of claim 1 , wherein the gas-phase side of the non-porous gas transfer membrane is contacted with H 2 gas at a sufficient partial pressure to convert at least 99% of the precious metal in the precious metal medium to elemental form.
7 . The method of claim 1 , wherein the sufficient partial pressure of H 2 gas to convert at least 90% of the precious metal in the precious metal medium to elemental form is 10±1 psig.
8 . The method of claim 1 , wherein the concentration of the precious metal in the precious metal medium is 0.1-5 mM.
9 . The method of claim 8 , wherein the concentration of the precious metal in the precious metal medium is 0.1±0.01 mM, 1±0.1 mM, 2±0.2 mM, or 5±0.5 mM.
10 . The method of claim 1 , wherein the solvent is selected from the group consisting of: water, salt solution, hydrochloric acid, methanol, ethanol, acetonitrile, toluene, dichloromethane, chloroform, and tetrahydrofuran.
11 . A method of removing oxidized contaminants from a fluid, the method comprising:
establishing a catalyst film, the catalyst film comprising precious metal nanoparticles on a non-porous gas transfer membrane;
contacting a fluid containing oxidized contaminants with the catalyst film; and
contacting the catalyst film with hydrogen (H 2 ) gas at a sufficient partial pressure to reduce the oxidized contaminants;
wherein the oxidized contaminants are selected from at least one member of the group consisting of: chlorophenols, 2,4-dichlorophenoxyacetic acid, 3,6-dichloro-2-methoxybenzoic acid, 1-chloro-3-ethylamino-5-isopropylamino-2,4,6-triazine, 3,5-dibromo-4-hydroxybenzonitrile, trichloroacetic acid, trichloroacetonitrile, NDMA, bromochloroiodomethane, chloroform, CFC-11, CFC-12, CFC-113, phenol, nitrophenols, PFAS 1,3,5-Trinitro-1,3,5-triazinane, 1,3,5,7-Tetranitro-1,3,5,7-tetrazoctane, and TNT.
12 . The method of claim 11 , wherein the step of establishing a catalyst film comprises:
providing the non-porous gas transfer membrane, the non-porous gas transfer membrane comprising a gas-phase side and a liquid-phase side;
contacting the liquid-phase side of the non-porous gas transfer membrane with a precious metal medium, the precious metal medium comprising a precious metal salt and a solvent; and
contacting the gas-phase side of the non-porous gas transfer membrane with H 2 gas at a sufficient partial pressure to convert at least 90% of the precious metal salt in the precious metal medium to elemental form.
13 . The method of claim 12 , wherein the catalyst film is deposed on the liquid-phase side of the non-porous gas transfer membrane.
14 . A method of establishing a catalyst film for long-term removal of oxidized contaminants from a fluid, the method comprising:
providing a non-porous gas transfer membrane, wherein the non-porous gas transfer membrane comprises a gas-phase side and a liquid-phase side;
contacting the liquid-phase side of the non-porous gas transfer membrane with a precious metal medium, the precious metal medium comprising a precious metal salt and a solvent; and
contacting the gas-phase side of the non-porous gas transfer membrane with hydrogen (H 2 ) gas at a sufficient partial pressure to convert at least 90% of the precious metal salt in the precious metal medium to an elemental form;
wherein:
the oxidized contaminants are selected from at least one member of the group consisting of: chlorophenols, 2,4-dichlorophenoxyacetic acid, 3,6-dichloro-2-methoxybenzoic acid, 1-chloro-3-ethylamino-5-isopropylamino-2,4,6-triazine, 3,5-dibromo-4-hydroxybenzonitrile, trichloroacetic acid, trichloroacetonitrile, NDMA, bromochloroiodomethane, chloroform, CFC-11, CFC-12, CFC-113, phenol, nitrophenols, PFAS, 1,3,5-Trinitro-1,3,5-triazinane, 1,3,5,7-Tetranitro-1,3,5,7-tetrazoctane, and TNT; and
the elemental form of the precious metal is in the form of a nanoparticle and is deposed on the liquid-phase side of the non-porous gas transfer membrane.
15 . The method of claim 14 , wherein the precious metal salt comprises palladium (II).
16 . The method of claim 15 , wherein the catalyst film consists of precious metal nanoparticles with a mean diameter of less than 5 nm.
17 . The method of claim 15 , wherein the precious metal salt further comprises rhodium (III), ruthenium (III), or iridium (IV).
18 . The method of claim 15 , wherein the precious metal salt consists of:
palladium (II),
palladium (II) and rhodium (III),
palladium (II) and ruthenium (III), or
palladium (II) and iridium (IV).
19 . The method of claim 14 , wherein the sufficient partial pressure of H 2 gas to convert at least 90% of the precious metal in the precious metal medium to elemental form is 10±1 psig.