Copper, iron and nitrogen treated adsorbent and method for producing same

Abstract

The carbonaceous material activated to form the precursor activated carbon is further improved by doping with copper, iron, and nitrogen and calcination. Carbonaceous materials include those derived from coal, wood, or coconut shells. Methods for doping the activated carbon are described. The described treatment process results in an adsorbent with excellent performance for removing chloramines and similar compounds from fluids, such as drinking water.

Description

[Technical Field]

[0001] REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 072,544, filed August 31, 2020, which is incorporated herein by reference in its entirety. Technical Field

[0002] Fluids, such as water, are routinely disinfected by adding oxidizing compounds, irradiating the water with ultraviolet light, or both. While these techniques are effective at disinfecting water, the disinfected water often contains the oxidizing compounds themselves, products of the oxidizing compounds when they dissolve in water, or reaction compounds resulting from irradiation of water containing various constituent compounds. Collectively, these various compounds include chlorine, chloramines, chloroform, trihalomethanes, haloacetic acids, organic peroxides, and hydrogen peroxide. These compounds are undesirable because they can change the odor and taste of the water, cause health problems, and potentially cause corrosion of water mains and pipes.

[0003] To remove these compounds, adsorbents are used. Adsorbents absorb and adsorb various compounds. In particular, the pores of the adsorbent allow for compound adsorption. However, pure adsorbents are inefficient, adsorbing only a small portion of the compounds that must be removed. To increase their effectiveness, adsorbents are sometimes treated with compounds to form catalytic adsorbents. The catalytic species are typically present on the surface of the adsorbent particles and function by catalyzing the chemical decomposition of undesirable compounds that are poorly adsorbed or absorbed on the adsorbent. By using both adsorption and catalytic mechanisms, catalytic adsorbents are significantly more efficient than pure, untreated adsorbents. Catalytic adsorbents have been demonstrated to be effective in removing chlorine, chloramines, chloroform, trihalomethanes, haloacetic acids, organic peroxides, and hydrogen peroxide from water and other fluids. Nevertheless, there remains a continuing need to improve the various processes that form such catalytic adsorbents, thereby improving overall adsorbent performance. The prior art documents relevant to the invention of this application are as follows (including documents cited in the international phase after the international filing date and documents cited when the application entered the national phase in other countries). 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[0004] The carbonaceous material that is activated to form the precursor activated carbon is further improved by doping with iron, copper, and nitrogen and calcining. The resulting adsorbent has excellent catalytic properties that are useful in the field of fluid purification.

[0005] 1. An adsorbent formed from a carbonaceous material that is activated to form a precursor activated carbon, the adsorbent comprising from about 2% to about 20% by weight nitrogen, measured on a dry precursor activated carbon basis, and from about 0.1% to about 4% by weight iron and copper, measured on a dry precursor activated carbon basis, and the adsorbent having a chloramine decomposition number (CDN) of from about 5 to about 75.

[0006] In another embodiment, the chloramine decomposition number is from about 20 to about 75.

[0007] In another embodiment, the adsorbent has a peroxide value of less than about 20 minutes.

[0008] In another embodiment, the adsorbent has a peroxide value of from about 1 minute to about 10 minutes.

[0009] In another embodiment, the amount of nitrogen is from about 2.5% to about 5% by weight.

[0010] In another embodiment, the amount of nitrogen is from about 1.4% to about 3.0% by weight.

[0011] In another embodiment, the sorbent is formed from a carbonaceous material formed from one or more of coal, wood, and coconut.

[0012] In another embodiment, at least a portion of the carbonaceous material is formed from coconut.

[0013] In another embodiment, the weight ratio of iron to copper is from about 25:75 to about 75:25.

[0014] In another embodiment, the weight ratio of iron to copper is about 50:50.

[0015] In one embodiment, there is a method of making an adsorbent, the method including: providing a carbonaceous material; activating the carbonaceous material to form a precursor activated carbon; optionally oxidizing the precursor activated carbon; doping the precursor activated carbon by contacting the precursor activated carbon with one or more compounds that are a copper source, an iron source, and a nitrogen source, thereby forming a doped precursor activated carbon; and calcining the doped precursor activated carbon by heating to a temperature of at least about 950° C. in a calcination atmosphere that does not cause any substantial oxidation or activation of the doped precursor activated carbon, thereby forming the adsorbent.

[0016] In another embodiment, the single compound is a copper source, an iron source, and a nitrogen source.

[0017] In another embodiment, the first compound is a copper source and an iron source, and the second compound is a nitrogen source.

[0018] In another embodiment, the first compound is a copper source and a nitrogen source, and the second compound is an iron source.

[0019] In another embodiment, the first compound is an iron source and a nitrogen source, and the second compound is a copper source.

[0020] In another embodiment, the first compound is a copper source, the second compound is an iron source, and the third compound is a nitrogen source.

[0021] In another embodiment, doping of the precursor activated carbon is carried out in a one-step process, which includes contacting the precursor activated carbon in an aqueous solution comprising a copper source, an iron source, and a nitrogen source.

[0022] In another embodiment, the copper source is copper(II) sulfate pentahydrate (CuSO . 5H2O), copper(II) chloride (CuCl2), copper(II) chloride dihydrate (CuCl2 . 2H2O), copper(II) nitrate (Cu(NO3)2), copper(II) nitrate monohydrate (Cu(NO3)2. H2O), copper(II) nitrate sesquihydrate (Cu(NO3)2 . 1.5H2O), copper(II) nitrate hemipentahydrate (Cu(NO3)2 . 2.5H2O), copper(II) nitrate trihydrate (Cu(NO3)2 . 3H2O), copper(II) nitrate hexahydrate (([Cu(H2O)6](NO3)2)), copper(II) acetate (Cu(CH3COO)2), copper(II) acetate monohydrate (Cu(CH3COO)2H2O), copper(II) formate tetrahydrate, Cu(NH3)6 +2 , copper(II) hydroxide carbonate, Cu2(OH)2CO3, compounds thereof, or mixtures thereof, and the iron source is one or more of iron(III) chloride hexahydrate (FeCl3·6H2O), iron(II) chloride tetrahydrate (FeCl2·4H2O), ammonium iron(III) sulfate dodecahydrate (NH4Fe(SO4)·12H2O), iron(II) sulfate heptahydrate (Fe2SO4·7H2O), ammonium iron(III) oxalate trihydrate ((NH4)3Fe(C2O4)3·3H2O), ammonium hexacyanoferrate(II) hydrate ((NH4)4[Fe(CN)6]·xH2O), ammonium iron(III) citrate ((NH4 )5[Fe(C6H4O7)2]), sodium ferrocyanide decahydrate (Na4Fe(CN)6·10H2O), sodium ferric oxalate (Na3Fe(C2O4)3), potassium ferrocyanide trihydrate (K4[Fe(CN)6]·3H2O), potassium ferricyanide (K3[Fe(CN)6]), potassium ferrous oxalate (K2[Fe(C2O4)2]), or iron(II) acetate tetrahydrate ((CH3COO)2Fe·4H2O), iron lactate dihydrate, iron lactate trihydrate, compounds thereof, or mixtures thereof, and the nitrogen source is one or more compounds in which nitrogen has an oxidation state of -3.

[0023] In another embodiment, the calcination is carried out at a temperature of about 800° C. to about 1050° C. in an N 2 atmosphere.

[0024] In another embodiment, oxidation is required and is performed.

[0025] In another embodiment, no oxidation is performed.

[0026] In another embodiment, the copper source is copper(II) sulfate pentahydrate (CuSO . 5H2O), the iron source is iron(III) chloride hexahydrate (FeCl3·6H2O), and the nitrogen source is one or more of urea or dicyandiamide (DCD).

[0027] In another embodiment, the calcination is carried out at a temperature of about 400° C. to about 1050° C. in an N 2 atmosphere.

[0028] In another embodiment, the calcination is carried out at a temperature of about 925°C to about 975°C in an N2 atmosphere.

[0029] In another embodiment, there is a method for removing chlorine, chloramines, or both chlorine and chloramines from a fluid, the method comprising: providing a sorbent, the sorbent formed from a carbonaceous material that is activated to form a precursor activated carbon, the sorbent comprising from about 2% to about 20% by weight nitrogen, measured on a dry precursor activated carbon basis, and from about 0.1% to about 4% by weight iron and copper, measured on a dry precursor activated carbon basis, the sorbent having a chloramine decomposition number (CDN) of from about 5 to about 75; and contacting the sorbent with the fluid.

[0030] In another embodiment, the fluid is liquid water.

[0031] In another embodiment, the water or adsorbent has previously undergone a disinfection process. [Brief explanation of the drawings]

[0032] Aspects, features, benefits, and advantages of the embodiments described herein will become apparent with regard to the following description, appended claims, and accompanying drawings.

[0033] [Figure 1] FIG. 1 illustrates a process according to one embodiment.

[0034] [Figure 2] FIG. 2 illustrates a process according to one embodiment.

[0035] [Figure 3] FIG. 3 illustrates a process according to one embodiment.

[0036] [Figure 4] Figure 4 shows the CDN and peroxide value versus the change in nitrogen content for Cu-Fe-N doped OLCs.

[0037] [Figure 5] FIG. 5 shows the CDN versus added metal loading using oxidized OLC.

[0038] [Figure 6] FIG. 6 shows the peroxide value versus added metal loading using oxidized OLC.

[0039] [Figure 7] FIG. 7 shows the CDN of oxidized OLCs doped with Cu—N, Fe—N, or Cu—Fe—N versus added nitrogen content.

[0040] [Figure 8] Figure 8 shows the CDN and peroxide values ​​versus the change in nitrogen content for Cu-Fe-N doped unoxidized OLCs.

[0041] [Figure 9] FIG. 9 shows the CDN versus added metal loading using unoxidized OLC.

[0042] [Figure 10] FIG. 10 shows the peroxide value versus added metal loading using unoxidized OLC. DETAILED DESCRIPTION OF THE INVENTION

[0043] The present disclosure is not limited to the particular systems, apparatus, and methods described, as these may vary. Moreover, the terminology used in the description is for the purpose of describing particular versions or embodiments only and is not intended to limit the scope of the invention. Furthermore, as described herein, any listing of a patent document, e.g., a U.S. patent, a U.S. patent application publication, a World Intellectual Property Organization publication, or a foreign patent application publication, means that such document is incorporated by reference in its entirety.

[0044] As used in this document, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Nothing herein should be construed as an admission that the embodiments described in this disclosure are not entitled to antedate such disclosure by virtue of prior invention. As used herein, the term "comprising" means "including, but not limited to."

[0045] As used herein, the term "about" means plus or minus 10% of the numerical value with which it is used. Thus, about 50% means a range of 45% to 55%.

[0046] As used herein, the term "adsorbent" refers to any material that exhibits adsorption, absorption, or a combination of adsorption and absorption properties. Adsorption refers to the physical attachment of atoms, ions, or molecules to the surface of the material. Absorption refers to the entry of atoms, ions, or molecules into and being retained by the bulk phase of the material. By way of example, adsorbents include activated carbon, reactivated carbon, natural and synthetic zeolites, silica, silica gel, alumina, zirconia, and diatomaceous earth. As used herein, an "adsorbent" is a material whose constituent components are substantially adsorbent and / or absorbent, with only minimal components that are not adsorbent and / or absorbent (e.g., the minimum amount of binder required for activated carbon pellets to maintain their shape).

[0047] As used herein, the term "sorbent" means any composition or composite that includes an adsorbent in a blend, mixture, composite, or compound with one or more additives that do not exhibit adsorbent properties. As an example, one embodiment of an adsorbent includes an activated carbon adsorbent mixed with a thermally conductive filler.

[0048] As used herein, the term "carbonaceous material" refers to a material containing carbon that has not been thermally or chemically activated. Carbonaceous materials may be mechanically, thermally, or chemically treated, and may even have weak adsorption properties, but do not adsorb compounds in the quantities expected of materials such as activated carbon. Examples of carbonaceous materials include, but are not limited to, bituminous coal, subbituminous coal, lignite, anthracite, wood, wood chips, sawdust, peat, nut shells, pits, coconut shells, babassu palm, macadamia nuts, dende nuts, peach pits, cherry pits, olive pits, walnut shells, wood, lignin, polymers, nitrogen-containing polymers, resins, petroleum pitch, bagasse, rice husks, corn husks, wheat husks and chaff, graphene, carbon nanotubes, or polymer fibers.

[0049] As used herein, the term "disinfection by-product" refers to compounds formed as a result of chemical reactions between organic and inorganic materials present in water, and compounds used during the disinfection process or compounds formed as a result of ultraviolet radiation exposure to organic and inorganic materials present in water. Examples of disinfection by-products include one or more of chlorine, chloramines, chloroform, trihalomethanes, haloacetic acids, organic peroxides, and hydrogen peroxide. However, it should be noted that compounds that are disinfection by-products may be present in water that has not undergone a disinfection process.

[0050] As used herein, the term "macropore" refers to pores within the adsorbent that are greater than about 50 nm in diameter.

[0051] As used herein, the term "mesopore" refers to pores within the adsorbent having diameters of about 2 nm to about 50 nm.

[0052] As used herein, the term "micropore" refers to pores within the adsorbent that are less than about 2 nm in diameter.

[0053] As used herein, "chloramine" means one or more of mono-chloramine (NH2Cl), di-chloramine (NHCl2), or tri-chloramine (NCl3).

[0054] The adsorbents or sorbents described herein are useful for removing chloroform and other similar volatile organic compounds (VOCs) from fluids, such as water. VOCs include styrene, alachlor, atrazine, benzene, carbofuran, carbon tetrachloride, chlorobenzene, chloropicrin, 2,4-dichlorophenoxyacetic acid (2,4-D), dibromochloropropane (DBCP), o-dichlorobenzene, p-dichlorobenzene, 1,2-dichloroethane, 1,1-dichloroethylene, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1,2-dichloropropane, cis-1,3-dichloropropylene, dinoseb, endrin, ethylbenzene, ethylene dibromide (EDB), haloacetonitriles (HANs), including bromochloroacetonitrile, dibromoacetonitrile, dichloroacetonitrile, and trichloroacetonitrile, 1,1-dichloro-2-propane, and one or more of haloketones (HK) including 1,1,1-trichloro-2-propanone, heptachlor (H-34, Heptox), heptachlor epoxide, hexachlorobutadiene, hexachlorocyclopentadiene, lindaine, methoxychlor, pentachlorophenol, simazine, styrene, 1,1,2,2-tetrachloroethane, tetrachloroethylene, toluene, 2,4,5-TP (Silvex), tribromoacetic acid, 1,2,4-trichlorobenzene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, bromoform, bromodichloromethane, trihalomethanes including chlorodibromomethane, or xylene. VOCs relevant to the drinking water sector are known in the industry and are described, for example, in NSF / ANSI 53-2019, designated a standard on May 6, 2019, which is incorporated by reference in its entirety. In some cases, VOC removal by an adsorbent or sorbent material is measured by the removal of the individual VOC species themselves. In other embodiments, VOC removal by an adsorbent or sorbent material is measured by the removal of a surrogate compound. A surrogate is a compound that is similar in chemical composition to the analyte of interest and that is present in the sample prior to preparation and analysis. For example, chloroform is an example of a surrogate for the compounds in this paragraph.

[0055] The adsorbents or sorbents described herein are also useful for removing other contaminants from water or other fluids, such as perfluoroalkyl and polyfluoroalkyl substances (PFAS). PFAS compounds include one or more of perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), and compounds produced by the GENX process, such as 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate and heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether.

[0056] The adsorbents or sorbents are also useful for removing a wide variety of emerging contaminants from water or other fluids, including one or more of meprobamate, phenytoin, atenolol, carbamazepine, tris(2-chloroethyl)phosphate (TCEP), tris(1-chloro-2-propyl)phosphate (TCPP), N,N-diethyl-meta-toluamide (DEET), metolachlor, trimethoprim, ibuprofen, naproxen, estrone, bisphenol A, linuron, or nonylphenol.

[0057] One embodiment of the overall process 10 of the present disclosure is illustrated in FIG. 1. In FIG. 1, a carbonaceous material is provided 20, and then the carbonaceous material is activated 30 to form a precursor activated carbon. Optionally, the precursor activated carbon is oxidized 40, meaning that oxidation 40 is performed in some embodiments, while oxidation 40 is not performed in certain other embodiments. After oxidation 40, the precursor activated carbon is doped 50, which provides the precursor activated carbon with certain amounts of copper, iron, and nitrogen dopants, thereby producing a doped precursor activated carbon. The doped precursor activated carbon is then calcined 60 by heating at a specific temperature and in a specific atmosphere, and cooled 70 in an inert atmosphere to substantially not change the pore structure and to substantially not oxidize or activate the doped precursor activated carbon. Completion of calcination 60 and cooling 70 produces an adsorbent material of the present disclosure.

[0058] Processing of carbonaceous materials The present disclosure provides one or more carbonaceous materials that are precursors to the final adsorbent. The carbonaceous materials may be mechanically, thermally, or chemically treated, and may even have weak adsorption properties, but the carbonaceous materials do not adsorb compounds in the quantities expected of materials such as activated carbon. Furthermore, the carbonaceous materials may be mechanically, thermally, or chemically treated, but they are not treated in a manner that activates the carbon. Examples of carbonaceous materials include, but are not limited to, bituminous coal, subbituminous coal, lignite, anthracite, wood, wood chips, sawdust, peat, nut shells, pits, coconut shells, babassu palm, macadamia nuts, dende nuts, peach pits, cherry pits, olive pits, walnut shells, wood, lignin, polymers, nitrogen-containing polymers, resins, petroleum pitch, bagasse, rice husks, corn husks, wheat husks and chaff, graphene, carbon nanotubes, or polymer fibers.

[0059] In some embodiments, the carbonaceous material is coconut. Coconut carbonaceous material is particularly useful because when coconut is activated to form activated carbon, it has excellent adsorption properties for chloroform and other organic compounds.

[0060] After the carbonaceous material is provided, it is processed through several non-limiting processing steps. These steps depend on the type of carbonaceous material and the desired form of the final activated carbon, and include one or more of the following: pyrolysis of the carbonaceous material to form charcoal, crushing the charcoal, mixing a binder with pulverized coal, briquetting the pulverized coal and binder, crushing the briquettes, sizing the crushed briquettes, and burning the sized briquettes or the briquettes themselves to carbonize, harden, or remove the binder. In all cases, however, the carbonaceous material in the form of fired briquettes or sized particles is thermally activated, chemically activated, or thermally and chemically activated. Thermal activation is performed by heating the fired briquettes or sized particles in the presence of one or more of water, oxygen, and carbon dioxide. Chemical activation is performed by impregnating the fired briquettes or sized particles in the presence of a strong acid, a strong base, or a salt. It should be noted that the inclusion of each of the above steps in the processing may vary depending on the carbonaceous material supplied. For example, if the carbonaceous material is coconut, the process steps would not include "reagglomeration" but would be mixing a binder with pulverized coal, compacting the pulverized coal and binder, crushing the compact, and adjusting the size of the crushed compact.

[0061] The processing of the carbonaceous material results in the formation of activated carbon. As described herein, this activated carbon is referred to as a "precursor activated carbon" because subsequent disclosures describe additional steps applied to the precursor activated carbon to further improve its performance. The performance of the precursor activated carbon depends on several factors, including the type and amount of one or more carbonaceous materials included, the type of activation, including chemical or thermal activation, and the level of activation imparted to the carbonaceous material to thereby form the precursor activated carbon. The performance of the precursor activated carbon is also affected by other processing steps, such as the milling and sizing of the reagglomerated carbonaceous material particles, the level of residual binder, and the final size of the precursor activated carbon.

[0062] In all embodiments, the precursor activated carbon is not separately treated or oxidized beyond the steps outlined above. Therefore, the precursor activated carbon maintains its own adsorption capacity and does not rely specifically on catalytic effects, resulting in a significant adsorption capacity for various disinfection by-products or other contaminant species. In some embodiments, the precursor activated carbon retains its adsorption capacity for substantially all organic compounds, including chloroform, VOCs, PFAS, and contaminants that emerge due to the internal pore structure of the precursor activated carbon.

[0063] Oxidation of precursor activated carbon The present disclosure contemplates any oxidation of the precursor activated carbon. In some embodiments, the precursor activated carbon is activated and then oxidized. In other embodiments, the precursor activated carbon is not activated and then oxidized. Oxidation of the precursor activated carbon refers to exposing the precursor activated carbon to molecular oxygen at a temperature sufficient to impart oxygen species or complexes on the surface of the activated carbon. Oxidation does not contemplate substantial modification of the pore structure of the precursor activated carbon.

[0064] For example, in some embodiments, oxidation is carried out by exposing the feedstock to an oxygen-containing environment and heating the feedstock to a temperature of about 150°C to about 1050°C. The temperature of oxidation may be about 150°C to about 250°C, about 250°C to about 350°C, about 350°C to about 450°C, about 450°C to about 550°C, about 550°C to about 650°C, about 650°C to about 750°C, or about 750°C to about 850°C, or any range comprising any of the disclosed endpoints or any combination of the above ranges or values ​​within those ranges. In other embodiments, the oxygen-containing environment is one or more of air, oxygen gas (O), oxygen plasma, hydrogen peroxide (H2O2), ozone (O3), nitrous oxide (N2O), or carbon dioxide (CO2).

[0065] In some embodiments, the oxygen-containing environment is dry and moisture-free or substantially moisture-free. The selection of the oxidation temperature and oxidizing agent and oxidation process does not substantially modify the pore structure of the precursor activated carbon. Therefore, if a more oxidizing oxygen-containing environment is selected, the temperature must be lowered to reduce the likelihood of further activation. Alternatively, if a higher temperature is selected, a less oxidizing oxygen-containing environment must be selected to reduce the likelihood of further activation.

[0066] Oxidation can also be accomplished electrochemically. Note that carbon oxidizes slowly in the presence of air with or without moisture at room temperature, and although this oxidation is slow, it is sufficient to eventually produce an oxidized carbon precursor. Alternatively, carbon may be oxidized in a non-thermal process using hydrogen peroxide, ozone, chlorine, persulfates, percarbonates, oxidizing acids such as nitric acid, air, pure oxygen, or any combination in the liquid or gas phase at temperatures below about 100°C. In some embodiments, the oxidation step is omitted, i.e., the sorbent feed material is not oxidized by any process faster than the slow oxidation described above that occurs spontaneously at room temperature under normal conditions.

[0067] Cu-Fe-N doping After the precursor activated carbon is prepared and optionally oxidized, it is further processed by doping with a copper-iron-nitrogen (Cu-Fe-N) compound. Doping with Cu-Fe-N imparts a Cu-Fe-N complex to the surface of the precursor activated carbon, thereby catalyzing disinfection by-products. Doping is achieved by contacting the precursor activated carbon with at least one copper source, at least one iron source, and at least one nitrogen source. In some embodiments, a single compound is a source of all three: copper, iron, and nitrogen. In yet other embodiments, a first compound is a source of copper and iron, and a second compound is a source of nitrogen. In yet other embodiments, a single compound is a source of copper and nitrogen, and a second compound is a source of iron. In yet other embodiments, a single compound is a source of iron and nitrogen, and a second compound is a source of copper.

[0068] The copper source is copper(II) sulfate pentahydrate (CuSO4 . 5H2O), copper(II) chloride (CuCl2), copper(II) chloride dihydrate (CuCl2 . 2H2O), copper(II) nitrate (Cu(NO3)2), copper(II) nitrate monohydrate (Cu(NO3)2 . H2O), copper(II) nitrate sesquihydrate (Cu(NO3)2 . 1.5H2O), copper(II) nitrate hemipentahydrate (Cu(NO3)2 . 2.5H2O), copper(II) nitrate trihydrate (Cu(NO3)2 . 3H2O), copper(II) nitrate hexahydrate (([Cu(H2O)6](NO3)2)), copper(II) acetate (Cu(CH3COO)2), copper(II) acetate monohydrate (Cu(CH3COO)2H2O), copper(II) formate tetrahydrate, Cu(NH3)6 +2 、In some embodiments, the copper source is provided as part of an aqueous solution. The copper source may be one or more of the following: copper hydroxide carbonate, Cu(OH)CO, compounds thereof, or mixtures thereof, or combinations thereof. In some embodiments, the copper source is provided as part of an aqueous solution. The iron source may be one or more of iron(III) chloride hexahydrate (FeCl·6H2O), iron(II) chloride tetrahydrate (FeCl·4H2O), ammonium iron(III) sulfate dodecahydrate (NH4Fe(SO4)·12H2O), iron(II) sulfate heptahydrate (Fe2SO4·7H2O), ammonium iron(III) oxalate trihydrate ((NH4)3Fe(C2O4)3·3H2O), ammonium hexacyanoferrate(II) hydrate ((NH4)4[Fe(CN)6]·xH2O), ammonium iron(III) citrate ((NH4)5[Fe(C6H4O7)2]), sodium ferrocyanide decahydrate ( Examples of suitable iron sources include, but are not limited to, one or more of: sodium ferric oxalate (NaFe(CN) 10H O), sodium ferric oxalate (NaFe(C O)), potassium ferrocyanide trihydrate (K[Fe(CN)] 3H O), potassium ferricyanide (K[Fe(CN)]), potassium ferrous oxalate (K[Fe(C O)]), iron(II) acetate tetrahydrate (CHCOO)Fe 4H O), iron lactate dihydrate, iron lactate trihydrate, urea (CO(NH)), dicyandiamide (DCD), compounds thereof, mixtures thereof, or combinations thereof. In some embodiments, the iron source is provided as part of an aqueous solution. The nitrogen source is not limited, and in some embodiments, includes any nitrogen source with an oxidation state of -3. Examples of nitrogen sources with an oxidation state of -3 include one or more ureas having the formula CO(NH) or dicyandiamide (DCD), or compounds thereof, mixtures thereof, or combinations thereof. In some embodiments, the nitrogen source is provided as part of an aqueous solution. Anhydrous copper or iron salt precursors, including CuCl, FeCl, and FeCl, are useful for the CuCl of the doping process. . Note the similarity to their hydrated counterparts, including FeCl₃·2H₂O, FeCl₃·6H₂O, and FeCl₂·4H₂O.

[0069] The above description of the nitrogen source, or a single source of iron or copper combined with nitrogen, or a single source of iron, copper, and nitrogen, includes several listed compounds, but such compounds in the combination of compounds are not so limited. In particular, applicants have found that those nitrogen compounds obtained in an oxidation state of -3 provide superior performance. Thus, in some embodiments, the nitrogen source is not limited, so long as the nitrogen source has an oxidation state of -3. The oxidation state of copper or iron is not believed to be critical to the results.

[0070] The doping process is not limited. In some embodiments, doping is carried out in one step. In the one-step process, the precursor activated carbon is treated by contacting the precursor activated carbon with a single solution, the single solution including a copper compound, an iron compound, and a nitrogen compound. For example, in one embodiment, doping is carried out in one step by contacting the precursor activated carbon with an aqueous solution including copper(II) sulfate pentahydrate, iron(III) chloride hexahydrate, and urea. In another embodiment, doping is carried out in one step by contacting the precursor activated carbon with an aqueous solution including copper(II) sulfate pentahydrate, iron(III) chloride hexahydrate, and dicyandiamide.

[0071] In the one-step process of doping the precursor activated carbon, the amount of copper compound, the amount of iron compound, and the amount of nitrogen compound doped can be controlled by one or more of: changing the concentration of the copper compound in the solution; changing the concentration of the iron compound in the solution; changing the nitrogen concentration in the solution; changing the length of time the solution is in contact with the precursor activated carbon; or changing the temperature of the solution.

[0072] After doping is achieved with the solution in the one-step process, the precursor activated carbon is dried to remove the water or other solvent, thereby leaving the copper, iron, and nitrogen compounds on the precursor activated carbon. The drying process is not limited and can be carried out by drying in air at about 100°C to about 150°C for up to 2 hours.

[0073] After the one-step process, the resulting doped and dried precursor activated carbon contains various amounts of copper, iron, and nitrogen. For example, the amount of copper added, measured on a dried precursor activated carbon basis, can be about 0.1 wt%, about 0.2 wt%, 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, about 0.7 wt%, about 0.8 wt%, about 0.9 wt%, about 1.0 wt%, about 1.1 wt%, about 1.2 wt%, about 1.3 wt%, about 1.4 wt%, about 1.5 wt%, about 1.6 wt%, about 1.7 wt%, about 1.8 wt%, about 1.9 wt%, about 2.0 wt%, about 2.1 wt%, about 2.2 wt%, about 2.3 wt%, about 2.4 wt%, about 2.5 wt%, about 2.6 wt%, about 2.7 wt%, about 2.8 wt%, about 2.9 wt%, about 3.0 wt%, about 3.1 wt%, about 3.2 wt%, about 3.3 wt%, about 3.4 wt%, about 3.5 wt%, about 3.6 wt%, about 3.7 wt%, about 3.8 wt%, about 3.9 wt%, about 3.9 wt%, about 4.0 wt%, about 4.1 wt%, about 4.2 wt%, about 4.3 wt%, about 4.4 wt%, about 4.5 wt%, about 4.6 wt%, about 4.7 wt%, about 4.8 wt%, about 4.9 wt%, about 4.9 wt%, about 5.0 wt%, about 5.1 wt%, about 5.2 wt%, about 5.3 wt%, about 5.4 wt%, about 5.5 wt%, about 5.6 wt%, about %, about 2.5 wt%, about 2.6 wt%, about 2.7 wt%, about 2.8 wt%, about 2.9 wt%, about 3.0 wt%, about 3.1 wt%, about 3.2 wt%, about 3.3 wt%, about 3.4 wt%, about 3.5 wt%, about 3.6 wt%, about 3.7 wt%, about 3.8 wt%, about 3.9 wt%, about 4.0 wt%, about 4.1 wt%, about 4.2 wt%, about 4.3 wt%, about 4.3 wt%, about 4.4 wt%, about 4.5 wt%, or any range including one or more of the above values ​​as endpoints. The amount of iron added, measured on a dry precursor activated carbon basis, is about 0.1 wt%, about 0.2 wt%, 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, about 0.7 wt%, about 0.8 wt%, about 0.9 wt%, about 1.0 wt%, about 1.1 wt%, about 1.2 wt%, about 1.3 wt%, about 1.4 wt%, about 1.5 wt%, about 1.6 wt%, about 1.7 wt%, about 1.8 wt%, about 1.9 wt%, about 2.0 wt%, about 2.1 wt%, about 2.2 wt%, about 2.3 wt%, about 2.4 wt%, about 2.5 wt%, about 2.6 wt%, about 2.7 wt%, about 2.8 wt%, about 2.9 wt%, about 3.0 wt%, about 3.1 wt%, about 3.2 wt%, about 3.3 wt%, about 3.4 wt%, about 3.5 wt%, about 3.6 wt%, about 3.7 wt%, about 3.8 wt%, about 3.9 wt%, about 4.0 wt%, about 4.1 wt%, about 4.2 wt%, about 4.3 wt%, about 4.4 wt%, about 4.5 wt%, about 4.6 wt%, about 4.7 wt%, about 4.8 wt%, about 4.9 wt%, about 5.0 wt%, about 5.1 wt%, about 5.2 wt%, about 5.3 wt%, about 5.4 wt%, about 5.5 wt%, about 5.6 wt%, about 5.7 wt%, about 5.8 wt%, about 5.9 wt%, about 6.0 wt%, about 6.1 wt%, about 6.2 wt%, %, about 2.5 wt%, about 2.6 wt%, about 2.7 wt%, about 2.8 wt%, about 2.9 wt%, about 3.0 wt%, about 3.1 wt%, about 3.2 wt%, about 3.3 wt%, about 3.4 wt%, about 3.5 wt%, about 3.6 wt%, about 3.7 wt%, about 3.8 wt%, about 3.9 wt%, about 4.0 wt%, about 4.1 wt%, about 4.2 wt%, about 4.3 wt%, about 4.3 wt%, about 4.4 wt%, about 4.5 wt%, or any range including one or more of the above values ​​as endpoints.The amount of nitrogen, as measured on a dry precursor activated carbon basis, is about 1.5 wt%, about 2.0 wt%, about 2.2 wt%, about 2.5 wt%, about 3.0 wt%, about 3.5 wt%, about 4.0 wt%, about 4.5 wt%, about 5.0 wt%, about 5.5 wt%, about 6.0 wt%, about 6.5 wt%, about 7.0 wt%, about 7.5 wt%, about 8.0 wt%, about 8.3 wt%, about 8.5 wt%, about 9.0 wt%, about 9.5 wt%, about 10.0 wt%, about 10.5 wt%, about 11.0 wt%, and about 11.5 wt%. 5% by weight, about 12.0% by weight, about 12.5% ​​by weight, about 13.0% by weight, about 13.5% by weight, about 14.0% by weight, about 14.5% by weight, about 15.0% by weight, about 15.5% by weight, about 16.0% by weight, about 16.5% by weight, about 16.7% by weight, about 17.0% by weight, about 17.5% by weight, about 18.0% by weight, about 18.5% by weight, about 19.0% by weight, about 19.5% by weight, about 20.0% by weight, or any range including one or more of the above values ​​as endpoints.

[0074] 2 illustrates one embodiment of a single-step doping process 50. In doping process 50, the precursor activated carbon is contacted with an aqueous solution containing a copper source, an iron source, and a nitrogen source, as indicated by box 51. The contacted precursor activated carbon is then dried 52. After drying, the doped precursor activated carbon is ready for calcination.

[0075] In another embodiment of the one-step process, precursor activated carbon is provided and then sprayed with an aqueous solution containing dissolved copper(II) sulfate pentahydrate, urea, and dissolved iron(III) chloride hexahydrate dopant. The precursor activated carbon is then allowed to stand for a predetermined period of time. After standing, the precursor activated carbon is dried for a predetermined period of time at a predetermined temperature. As an example, the aqueous solution contains about 0.19 wt.% Cu, about 12.1 wt.% N, and about 0.19 wt.% Fe, each measured by the weight of the dried precursor activated carbon. Furthermore, the standing time can be about 40 minutes, about 50 minutes, about 60 minutes, about 70 minutes, or about 80 minutes. Drying is performed at a temperature of about 100°C for about 4 hours, but the drying time and temperature can be varied. Once the drying process is complete, the doped precursor activated carbon is ready for calcination.

[0076] In another embodiment, the doping is carried out in two stages. In the two-stage process, the precursor activated carbon is treated by first contacting the precursor activated carbon with a solution containing copper and iron and optionally drying the precursor activated carbon containing copper and iron, and second contacting the precursor activated carbon containing copper and iron with a solution containing nitrogen and drying the precursor activated carbon containing copper, iron, and nitrogen. In another two-stage process, the precursor activated carbon is treated by first contacting the precursor activated carbon with a solution containing copper and nitrogen and optionally drying the precursor activated carbon containing copper and nitrogen, and second contacting the precursor activated carbon with a solution containing iron and drying the precursor activated carbon containing copper, iron, and nitrogen. In another two-stage process, the precursor activated carbon is treated by first contacting the precursor activated carbon with a solution containing copper and nitrogen and optionally drying the precursor activated carbon containing copper and nitrogen, and second contacting the precursor activated carbon with a solution containing iron and drying the precursor activated carbon containing copper, iron, and nitrogen. In another two-step process, the precursor activated carbon is treated by first contacting the precursor activated carbon with a solution containing iron and nitrogen and optionally drying the precursor activated carbon containing iron and nitrogen, and second contacting the precursor activated carbon containing iron and nitrogen with a solution containing copper and drying the precursor activated carbon containing copper, iron, and nitrogen.

[0077] In one such embodiment, doping is carried out in two steps by first contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate and dissolved iron(III) chloride hexahydrate, and second contacting the precursor activated carbon with an aqueous solution of urea. In one such embodiment, doping is carried out in two steps by first contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate and dissolved urea, and second contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate. In one such embodiment, doping is carried out in two steps by first contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate and aqueous solution of urea, and second contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate.

[0078] In another embodiment, two-step doping is carried out by first contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate and an aqueous solution containing dissolved iron(III) chloride hexahydrate, and secondly contacting the precursor activated carbon with an aqueous solution of dicyandiamide. In another embodiment, doping is carried out in two steps by first contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate and an aqueous solution of dicyandiamide, and secondly contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate. In another embodiment, doping is carried out in two steps by first contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate and an aqueous solution of dicyandiamide, and secondly contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate.

[0079] In the two-step process of doping the precursor activated carbon, the amount of copper compound, the amount of iron compound, and the amount of nitrogen compound doped can be controlled by one or more of: changing the concentration of the copper compound in the solution; changing the concentration of the iron compound in the solution; changing the concentration of the nitrogen compound in the solution; changing the length of time that one or more of the copper-containing solution, iron-containing solution, or nitrogen-containing solution contacts the precursor activated carbon; or changing the temperature of one or more of the copper-containing solution, iron-containing solution, or nitrogen-containing solution.

[0080] After the two-step process, the resulting doped and dried precursor activated carbon contains specific amounts of copper, iron, and nitrogen. For example, the amount of copper, as measured on a dried precursor activated carbon basis, can be about 0.1 wt%, about 0.2 wt%, 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, about 0.7 wt%, about 0.8 wt%, about 0.9 wt%, about 1.0 wt%, about 1.1 wt%, about 1.2 wt%, about 1.3 wt%, about 1.4 wt%, about 1.5 wt%, about 1.6 wt%, about 1.7 wt%, about 1.8 wt%, about 1.9 wt%, about 2.0 wt%, about 2.1 wt%, about 2.2 wt%, about 2.3 wt%, about 2.4 wt%, about 2.5 wt%, about 2.6 wt%, about 2.7 wt%, about 2.8 wt%, about 2.9 wt%, about 3.0 wt%, about 3.1 wt%, about 3.2 wt%, about 3.3 wt%, about 3.4 wt%, about 3.5 wt%, about 3.6 wt%, about 3.7 wt%, about 3.8 wt%, about 3.9 wt%, about 4.0 wt%, about 4.1 wt%, about 4.2 wt%, about 4.3 wt%, about 4.4 wt%, about 4.5 wt%, about 4.6 wt%, about 4.7 wt%, about 4.8 wt%, about 4.9 wt%, about 5.0 wt%, about 5.1 wt%, about 5.2 wt%, about 5.3 wt%, about 5.4 wt%, about 5.5 wt%, about 5.6 wt%, about 5.7 wt%, about 5.8 wt%, about %, about 2.3 weight%, about 2.4 weight%, about 2.5 weight%, about 2.6 weight%, about 2.7 weight%, about 2.8 weight%, about 2.9 weight%, about 3.0 weight%, about 3.1 weight%, about 3.2 weight%, about 3.3 weight%, about 3.4 weight%, about 3.5 weight%, about 3.6 weight%, about 3.7 weight%, about 3.8 weight%, about 3.9 weight%, about 4.0 weight%, about 4.1 weight%, about 4.2 weight%, about 4.3 weight%, about 4.3 weight%, about 4.4 weight%, and about 4.5 weight%. The amount of iron, measured on a dry precursor activated carbon basis, is about 0.1 wt%, about 0.2 wt%, 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, about 0.7 wt%, about 0.8 wt%, about 0.9 wt%, about 1.0 wt%, about 1.1 wt%, about 1.2 wt%, about 1.3 wt%, about 1.4 wt%, about 1.5 wt%, about 1.6 wt%, about 1.7 wt%, about 1.8 wt%, about 1.9 wt%, about 2.0 wt%, about 2.1 wt%, about 2.2 wt%, about 2.3 wt%, about 2.4 wt%, about 2.5 wt%, about 2.6 wt%, about 2.7 wt%, about 2.8 wt%, about 2.9 wt%, about 3.0 wt%, about 3.1 wt%, about 3.2 wt%, about 3.3 wt%, about 3.4 wt%, about 3.5 wt%, about 3.6 wt%, about 3.7 wt%, about 3.8 wt%, about 3.9 wt%, about 4.0 wt%, about 4.1 wt%, about 4.2 wt%, about 4.3 wt%, about 4.3 wt%, about 4.4 wt%, about 4.5 wt%, or any range including one or more of the above values ​​as endpoints.The amount of nitrogen, as measured on a dry precursor activated carbon basis, is about 1.5 wt%, about 2.0 wt%, about 2.2 wt%, about 2.5 wt%, about 3.0 wt%, about 3.5 wt%, about 4.0 wt%, about 4.5 wt%, about 5.0 wt%, about 5.5 wt%, about 6.0 wt%, about 6.5 wt%, about 7.0 wt%, about 7.5 wt%, about 8.0 wt%, about 8.3 wt%, about 8.5 wt%, about 9.0 wt%, about 9.5 wt%, about 10.0 wt%, about 10.5 wt%, about 11.0 wt%, and about 11.5 wt%. 5% by weight, about 12.0% by weight, about 12.5% ​​by weight, about 13.0% by weight, about 13.5% by weight, about 14.0% by weight, about 14.5% by weight, about 15.0% by weight, about 15.5% by weight, about 16.0% by weight, about 16.5% by weight, about 16.7% by weight, about 17.0% by weight, about 17.5% by weight, about 18.0% by weight, about 18.5% by weight, about 19.0% by weight, about 19.5% by weight, about 20.0% by weight, or any range including one or more of the above values ​​as endpoints.

[0081] 3 illustrates one embodiment of a two-step doping process 50. In doping process 50, a precursor activated carbon is contacted with an aqueous solution containing a copper source and an iron source, as indicated by box 51. The precursor activated carbon is then dried 52. After drying 52, the precursor activated carbon is contacted with an aqueous solution containing a nitrogen source, as indicated by box 53. After contact with the aqueous solution containing the nitrogen source, the precursor activated carbon is dried 54. After this second drying step, the doped precursor activated carbon is ready for calcination.

[0082] In another embodiment, the doping is carried out in three steps. In the three-step process, the precursor activated carbon is treated by first contacting the precursor activated carbon with a copper-containing solution and optionally drying the copper-containing precursor activated carbon; second contacting the copper-containing precursor activated carbon with an iron-containing solution and optionally drying the copper and iron-containing precursor activated carbon; and third contacting the copper and iron-containing precursor activated carbon with a nitrogen-containing solution and drying the copper, iron, and nitrogen-containing precursor activated carbon. In another three-step process, the precursor activated carbon is treated by first contacting the precursor activated carbon with an iron-containing solution and optionally drying the iron-containing precursor activated carbon; second contacting the iron-containing precursor activated carbon with a copper-containing solution and optionally drying the iron and copper-containing precursor activated carbon; and third contacting the iron and copper-containing precursor activated carbon with a nitrogen-containing solution and drying the copper, iron, and nitrogen-containing precursor activated carbon. In another three-step process, the precursor activated carbon is treated by, first, contacting the precursor activated carbon with a copper-containing solution and optionally drying the copper-containing precursor activated carbon, second, contacting the copper-containing precursor activated carbon with a nitrogen-containing solution and optionally drying the copper- and iron-containing precursor activated carbon, and third, contacting the copper- and nitrogen-containing precursor activated carbon with an iron-containing solution and drying the copper-, iron-, and nitrogen-containing precursor activated carbon. In another three-step process, the precursor activated carbon is treated by, first, contacting the precursor activated carbon with an iron-containing solution and optionally drying the iron-containing precursor activated carbon, second, contacting the copper-containing precursor activated carbon with a nitrogen-containing solution and optionally drying the iron- and nitrogen-containing precursor activated carbon, and third, contacting the iron- and nitrogen-containing precursor activated carbon with a copper-containing solution and drying the copper-, iron-, and nitrogen-containing precursor activated carbon. In another three-step process, the precursor activated carbon is treated by first contacting the precursor activated carbon with a nitrogen-containing solution and optionally drying the nitrogen-containing precursor activated carbon; second contacting the nitrogen-containing precursor activated carbon with a copper-containing solution and optionally drying the nitrogen- and copper-containing precursor activated carbon; and third contacting the nitrogen- and copper-containing precursor activated carbon with an iron-containing solution and drying the copper-, iron-, and nitrogen-containing precursor activated carbon.In another three-step process, the precursor activated carbon is treated by first contacting the precursor activated carbon with a nitrogen-containing solution and optionally drying the nitrogen-containing precursor activated carbon; second contacting the nitrogen-containing precursor activated carbon with an iron-containing solution and optionally drying the nitrogen- and iron-containing precursor activated carbon; and third contacting the nitrogen- and iron-containing precursor activated carbon with a copper-containing solution and drying the copper, iron, and nitrogen-containing precursor activated carbon.

[0083] In one such embodiment, doping is carried out in three steps by first contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate, second contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate, and third contacting the precursor activated carbon with an aqueous solution of urea. In another embodiment, doping is carried out in three steps by first contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate, second contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate, and third contacting the precursor activated carbon with an aqueous solution of urea. In another embodiment, doping is carried out in three steps by first contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate, second contacting the precursor activated carbon with an aqueous solution of urea, and third contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate. In another embodiment, doping is carried out in three steps by first contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate, second contacting the precursor activated carbon with an aqueous solution of urea, and third contacting the precursor activated carbon with an aqueous solution of dissolved copper(II) sulfate pentahydrate. In another embodiment, doping is carried out in three steps by first contacting the precursor activated carbon with an aqueous solution of urea, second contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate, and third contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate. In another embodiment, doping is carried out in three steps by first contacting the precursor activated carbon with an aqueous solution of urea, second contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate, and third contacting the precursor activated carbon with an aqueous solution of dissolved copper(II) sulfate pentahydrate.

[0084] In another embodiment, a three-step doping is carried out by first contacting the precursor activated carbon with an aqueous solution of dissolved copper(II) sulfate pentahydrate, second contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate, and third contacting the precursor activated carbon with an aqueous solution of dicyandiamide. In another embodiment, the doping is carried out in three steps by first contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate, second contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate, and third contacting the precursor activated carbon with an aqueous solution of dicyandiamide. In another embodiment, the doping is carried out in three steps by first contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate, second contacting the precursor activated carbon with an aqueous solution of dicyandiamide, and third contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate. In another embodiment, doping is carried out in three steps by first contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate, second contacting the precursor activated carbon with an aqueous solution of dicyandiamide, and third contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate. In another embodiment, doping is carried out in three steps by first contacting the precursor activated carbon with an aqueous solution of dicyandiamide, second contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate, and third contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate. In another embodiment, doping is carried out in three steps by first contacting the precursor activated carbon with an aqueous solution of dicyandiamide, second contacting the precursor activated carbon with an aqueous solution containing dissolved iron(III) chloride hexahydrate, and third contacting the precursor activated carbon with an aqueous solution containing dissolved copper(II) sulfate pentahydrate.

[0085] In the three-step process of doping the precursor activated carbon, the amount of copper compound, the amount of iron compound, and the amount of nitrogen compound doped can be controlled by one or more of: changing the concentration of the copper compound in the solution; changing the concentration of the iron compound in the solution; changing the concentration of the nitrogen compound in the solution; changing the length of time that one or more of the copper-containing solution, iron-containing solution, or nitrogen-containing solution contacts the precursor activated carbon; or changing the temperature of one or more of the copper-containing solution, iron-containing solution, or nitrogen-containing solution.

[0086] After the three-step process, the resulting doped and dried precursor activated carbon contains specific amounts of copper, iron, and nitrogen. For example, the amount of copper added, measured on a dried precursor activated carbon basis, can be about 0.1 wt%, about 0.2 wt%, 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, about 0.7 wt%, about 0.8 wt%, about 0.9 wt%, about 1.0 wt%, about 1.1 wt%, about 1.2 wt%, about 1.3 wt%, about 1.4 wt%, about 1.5 wt%, about 1.6 wt%, about 1.7 wt%, about 1.8 wt%, about 1.9 wt%, about 2.0 wt%, about 2.1 wt%, about 2.2 wt%, about 2.3 wt%, about 2.4 wt%, about 2.5 wt%, about 2.6 wt%, about 2.7 wt%, about 2.8 wt%, about 2.9 wt%, about 3.0 wt%, about 3.1 wt%, about 3.2 wt%, about 3.3 wt%, about 3.4 wt%, about 3.5 wt%, about 3.6 wt%, about 3.7 wt%, about 3.8 wt%, about 3.9 wt%, about 4.0 wt%, about 4.1 wt%, about 4.2 wt%, about 4.3 wt%, about 4.4 wt%, about 4.5 wt%, about 4.6 wt%, about 4.7 wt%, about 4.8 wt%, about 4.9 wt%, about 4.9 wt%, about 5.0 wt%, about 5.1 wt%, about 5.2 wt%, about 5.3 wt%, about 5.4 wt%, about 5.5 wt%, about 5.6 wt%, about 5.7 wt%, about %, about 2.5 wt%, about 2.6 wt%, about 2.7 wt%, about 2.8 wt%, about 2.9 wt%, about 3.0 wt%, about 3.1 wt%, about 3.2 wt%, about 3.3 wt%, about 3.4 wt%, about 3.5 wt%, about 3.6 wt%, about 3.7 wt%, about 3.8 wt%, about 3.9 wt%, about 4.0 wt%, about 4.1 wt%, about 4.2 wt%, about 4.3 wt%, about 4.3 wt%, about 4.4 wt%, about 4.5 wt%, or any range including one or more of the above values ​​as endpoints. The amount of iron added, measured on a dry precursor activated carbon basis, is about 0.1 wt%, about 0.2 wt%, 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, about 0.7 wt%, about 0.8 wt%, about 0.9 wt%, about 1.0 wt%, about 1.1 wt%, about 1.2 wt%, about 1.3 wt%, about 1.4 wt%, about 1.5 wt%, about 1.6 wt%, about 1.7 wt%, about 1.8 wt%, about 1.9 wt%, about 2.0 wt%, about 2.1 wt%, about 2.2 wt%, about 2.3 wt%, about 2.4 wt%, about 2.5 wt%, about 2.6 wt%, about 2.7 wt%, about 2.8 wt%, about 2.9 wt%, about 3.0 wt%, about 3.1 wt%, about 3.2 wt%, about 3.3 wt%, about 3.4 wt%, about 3.5 wt%, about 3.6 wt%, about 3.7 wt%, about 3.8 wt%, about 3.9 wt%, about 4.0 wt%, about 4.1 wt%, about 4.2 wt%, about 4.3 wt%, about 4.4 wt%, about 4.5 wt%, about 4.6 wt%, about 4.7 wt%, about 4.8 wt%, about 4.9 wt%, about 5.0 wt%, about 5.1 wt%, about 5.2 wt%, about 5.3 wt%, about 5.4 wt%, about 5.5 wt%, about 5.6 wt%, about 5.7 wt%, about 5.8 wt%, about 5.9 wt%, about 6.0 wt%, about 6.1 wt%, about 6.2 wt%, %, about 2.5 wt%, about 2.6 wt%, about 2.7 wt%, about 2.8 wt%, about 2.9 wt%, about 3.0 wt%, about 3.1 wt%, about 3.2 wt%, about 3.3 wt%, about 3.4 wt%, about 3.5 wt%, about 3.6 wt%, about 3.7 wt%, about 3.8 wt%, about 3.9 wt%, about 4.0 wt%, about 4.1 wt%, about 4.2 wt%, about 4.3 wt%, about 4.3 wt%, about 4.4 wt%, about 4.5 wt%, or any range including one or more of the above values ​​as endpoints.The amount of nitrogen, as measured on a dry precursor activated carbon basis, is about 1.5 wt%, about 2.0 wt%, about 2.2 wt%, about 2.5 wt%, about 3.0 wt%, about 3.5 wt%, about 4.0 wt%, about 4.5 wt%, about 5.0 wt%, about 5.5 wt%, about 6.0 wt%, about 6.5 wt%, about 7.0 wt%, about 7.5 wt%, about 8.0 wt%, about 8.3 wt%, about 8.5 wt%, about 9.0 wt%, about 9.5 wt%, about 10.0 wt%, about 10.5 wt%, about 11.0 wt%, and about 11.5 wt%. 5% by weight, about 12.0% by weight, about 12.5% ​​by weight, about 13.0% by weight, about 13.5% by weight, about 14.0% by weight, about 14.5% by weight, about 15.0% by weight, about 15.5% by weight, about 16.0% by weight, about 16.5% by weight, about 16.7% by weight, about 17.0% by weight, about 17.5% by weight, about 18.0% by weight, about 18.5% by weight, about 19.0% by weight, about 19.5% by weight, about 20.0% by weight, or any range including one or more of the above values ​​as endpoints.

[0087] Although one-step, two-step, and three-step Cu-Fe-N doping processes are disclosed above, the processes are not limited thereto. For example, additional dopants can be applied in additional steps or as part of any solution that contacts the precursor activated carbon.

[0088] The iron to copper ratio is not limited, and in some embodiments, the iron to copper ratio is about 10:90 to about 90:10, about 30:70 to about 70:30, about 60:40 to about 40:60, about 50:50, or any range within the foregoing ranges.

[0089] Heat treatment / calcination After one or more of the one-stage, two-stage, and three-stage Cu-Fe-N doping processes are complete, the doped precursor activated carbon is ready for a heat treatment, also known as calcination, during which the doped precursor activated carbon is heated in the presence of an inert atmosphere to achieve further transformation of the doped precursor activated carbon.

[0090] The calcination temperature of the doped precursor activated carbon is not limited. In some embodiments, the calcination is carried out at about 400°C, about 450°C, about 500°C, about 550°C, about 600°C, about 650°C, about 700°C, about 750°C, about 800°C, about 850°C, about 900°C, about 950°C, about 1000°C, about 1050°C, or any range of temperatures including one or more of the above values ​​as endpoints. In one embodiment, the calcination temperature is from about 900°C to about 1000°C.

[0091] An inert atmosphere for calcination is one that does not cause any substantial oxidation or activation of the doped precursor activated carbon at a particular temperature so as not to alter the pore structure of the doped precursor activated carbon. Thus, in many embodiments, the atmosphere contains no oxygen, carbon dioxide, or water, or the atmosphere contains oxygen, carbon dioxide, or water in amounts so small that no oxidation or activation occurs. Examples of calcination atmospheres include one or more of nitrogen gas (N), helium, neon, argon, krypton, xenon, and combinations thereof. Once calcination is complete, the resulting product is called an adsorbent.

[0092] In some embodiments, the adsorbent is granular activated carbon (GAC), defined as activated carbon particles sized to fit over a 50-mesh sieve (approximately 0.300 mm openings). In another embodiment, the adsorbent is powdered activated carbon (PAC), defined as particles that pass through an 80-mesh sieve (approximately 0.180 mm openings). While these particle size ranges are mentioned for activated carbon adsorbents, it is contemplated that any disclosed adsorbent may be measured by the above 50-mesh and 80-mesh sieve sizes. In yet another embodiment, the adsorbent is pelleted activated carbon.

[0093] Performance measurement / adsorption property evaluation The performance of the adsorbents of the present disclosure is measured in various ways, including the "chloramine decomposition number" (CDN), defined below. The chloramine decomposition number quantifies the amount of chloramine that can be removed from a fluid by the adsorbents of the present disclosure. Measurement of the CDN is known in the art, for example, U.S. Pat. No. 10,702,853, issued July 7, 2020, entitled "CHLORAMINE AND CHLORINE REMOVAL MATER AND HOD FOR MAKING THE SAME," which is incorporated herein by reference in its entirety.

[0094] The CDN is the absolute value multiplied by 1000 of a first-order linear kinetic fit applied to the natural logarithm of the chloramine concentration in water versus time, decreasing the initial chloramine concentration over 150 minutes. When ammonia is in equilibrium with the chlorine in solution, the form of chloramine is pH dependent. The chloramine solution contained ammonium chloride, sodium hypochlorite, and deionized water, resulting in a 1 L solution of 300 ppm chloramine at pH 9.0. At pH 9.0, the chloramine species present at equilibrium is the monochloramine form, which is the most difficult to decompose. Sodium carbonate was used to buffer the solution and maintain the solution pH during the evaluation. The chlorine solution contained sodium hypochlorite and deionized water, resulting in 1 L of 300 ppm chlorine solution. One liter of each 300 ppm solution was added to an Erlenmeyer flask placed in a water bath controlled at 20°C. For each sample run, a fixed volume of 2.0 mL of activated carbon (sized at 80 x 325 mesh) was added to 1 L of stirred chloramine or chlorine solution. The volume of carbon used was determined from the apparent density of 80 x 325 carbon measured by ASTM Method D-2854. The total chlorine concentration in the solution was measured at various time points over a 150-minute period by taking an aliquot and then analyzing it for total chlorine using standard HACH colorimetric EPA-approved Method 10070.

[0095] After the adsorbents were experimentally analyzed, the concentration versus time data for each adsorbent sample was replotted as the natural logarithm of total chlorine concentration versus time to linearize the data according to first-order kinetics. A linear fit was then applied to the data, and the slope of the linear fit was determined. Because the initial total chlorine concentration decreased over the 150 minutes, the slope was always negative. The absolute value of the slope, multiplied by 1000, was then used to quantify the rate of chloramine and chlorine degradation (removal). The greater the absolute slope, the more effective the adsorbent was at removing chlorine and chloramine. In these measurements, the slope resulting from the linear fit of the first-order kinetic experimental data (again multiplied by 1000) is referred to as the "chloramine decomposition number," or CDN. In the case of chlorine decomposition, this rate is referred to as the "chlorine decomposition number" of Cl-DN. These values ​​quantify the amount of chloramine and / or chlorine that can be removed from water by the adsorbents or sorbents of the present disclosure.

[0096] In addition to chloramines, the present disclosure is also effective for removing chlorine from fluids, such as aqueous streams. The ability of calcined activated carbon to remove chlorine was evaluated as described above, except that test solutions were made without the addition of ammonium chloride, thus containing 300 ppm chlorine. The particle size of the adsorbent for chlorine analysis was 95% approximately 325 mesh. However, the analysis of the chlorine concentration versus time data and the corresponding first-order kinetic slope remained the same, and the slope of the linear fit of this data is referred to as the "chlorine decomposition value," or Cl-DN, which again quantifies the amount of chlorine that can be removed from water by the adsorbents or sorbents of the present disclosure.

[0097] For CDNs, this disclosure uses values ​​of about 3.0, about 3.5, about 4.0, about 4.5, about 5.0, about 5.5, about 6.0, about 6.5, about 7.0, about 7.5, about 8.0, about 8.5, about 9.0, about 9.5, about 10.0, about 10.5, about 11.0, about 12.0, about 12.5, about 13.0, about 13.5, and about 14. 0, about 14.5, about 15.0, about 15.5, about 16.0, about 16.5, about 17.0, about 17.5, about 18.0, about 18.5, about 19.0, about 19.5, about 20.0, about 20.5, about 21.0, about 21.5, about 22.0, about 22.5, about 23.0, about 23.5, about 24.0, about 24.5, about 2 Contemplated are values ​​of 5.0, about 25.5, about 26.0, about 26.5, about 27.5, about 28.0, about 28.5, about 29.0, about 29.5, about 30.0, about 35.0, about 40.0, about 45.0, about 50.0, about 55.0, about 60.0, about 65.0, about 70.0, about 75.0, about 80.0, about 85.0, about 90.0, about 95.0, about 100.0, about 105.0, about 110.0, about 115.0, about 120.0, about 125.0, about 130.0, about 135.0, about 140.0, about 145.0, about 150.0, or any range of values ​​including at least two of these values ​​as endpoints. Alternatively, the CDN can be a range that includes these numbers as the lower end of the performance range, e.g., at least about 4.0, at least about 4.5, at least about 5.0, at least about 10.0, at least about 15.0, at least about 20.0, at least about 23.0, at least about 50.0, at least about 75.0, or at least about 100.0. In some embodiments, the chloramine decomposition number is measured with respect to mono-chloramines.

[0098] Also measured is the "peroxide decomposition number," also known as the "peroxide value." The peroxide value is a volumetric test, meaning that performance is measured and normalized to a specific volume of the adsorbent. Peroxide value testing is well known in the art and is described, for example, in U.S. Pat. No. 5,470,748, which is incorporated herein by reference in its entirety.

[0099] During peroxide value testing, the adsorbent is first ground to a fine mesh size fraction, with at least 90% by weight of the adsorbent, and in certain tests, at least 95% by weight, passing through a 325-mesh U.S. Standard Series sieve (44 μm opening size). A specific amount of ground adsorbent is placed in a vacuum flask (Dewar), and 100 mL of deionized water is added to the vacuum flask. The deionized water is added so that any ground adsorbent adhering to the sides of the vacuum flask is carried into the body of water at the bottom of the vacuum flask. Next, a 50 mL aliquot of aqueous buffer solution is added to the vacuum flask. The aqueous buffer solution is 0.5 molar in KHPO and 0.5 molar in KHPO. After the aqueous buffer solution is added, a magnetic stir bar is added to the vacuum flask and energized to begin stirring. The stirring speed is increased until a vortex greater than approximately 0.5 inches (1.27 cm) deep is formed in the mixture and the optimum stir bar speed is achieved. The optimum stir bar speed is selected such that further increases in stir bar speed do not significantly affect the decomposition time of the peroxide.

[0100] As explained in the previous paragraph, during the peroxide value test, a specific amount of adsorbent is added to a hydrogen peroxide buffer solution. Because this test is a volumetric test, the specific amount of adsorbent added to the hydrogen peroxide buffer solution is based on half (1 / 2) the apparent density of the adsorbent. Specifically, if the apparent density of the adsorbent is g / cm 3 When reported as , the mass in grams of adsorbent added to the solution is equal to one-half (1 / 2) of the adsorbent's measured apparent density. In buffer solutions, the catalytic properties of the adsorbent catalyze the peroxides, thereby causing their decomposition (i.e., hydrogen peroxide decomposes into water and oxygen gas).

[0101] Hydrogen peroxide catalysis is exothermic. Therefore, the rate of decomposition by the adsorbent can be estimated over time by measuring the temperature of the buffer solution. As used herein, "peroxide value" is the time in minutes required for the buffer solution containing the adsorbent sample to reach 75% of the maximum recorded temperature. A faster time, and therefore a smaller value, for the peroxide value indicates a more catalytically active and therefore better performing adsorbent. In some embodiments, the peroxide decomposition number measured in minutes is about 1.0, about 1.5, about 2.0, about 2.1, about 2.2, about 2.3, about 2.4, about 2.5, about 2.6, about 2.7, about 2.8, about 2.9, about 3.0, about 3.1, about 3.2, about 3.3, about 3.4, about 3.5, about 3.6, about 3.7, about 3.8, about 3.9, about 4.0, about 4.1, about 4.2, about 4.3, about 4.4, about 4.5, about 4.6, about 4.7, about 4.8, about 4.9, about 5.0, about 5.1, about 5.2, about 5.3, about 5.4, about 5.5, about 5.6, about 5.7, about 5.8, about 5.9, about 6.0, about 6.1, about 6.2, about 6.3, about 6.4, about 6.5, about 6.6, about 6.7, about 6.8, about 6.9, about 7.0, about 7.1, about 7.2, about 7.3, about 7.4, about 7.5, about 7.6, about 7.7, about 7.8, about 7.9, about 8.0, about 8.1, about 8.1, about 8.2, about 8.3, about 8.4, about 8.5, about 8.6, about 8.7, about 8.8, about 8.9, about 9.0, about 9.1, about 9.2, about 9.3, about 9.4, about 9.5, about 9.6, about 9.7, about 9.8, about 9. .2, about 5.3, about 5.4, about 5.5, about 5.6, about 5.7, about 5.8, about 5.9, about 6.0, about 6.1, about 6.2, about 6.3, about 6.4, about 6.5, about 6.6, about 6.7, about 6.8, about 6.9, about 7.0, about 7.1, about 7.2, about 7.3, about 7.4, about 7.5, about 7.6, about 7.7, about 7.8, about 7.9, about 8.0, about 8.1, about 8.2, about 8.3, about 8.4, about 8.5, about 8.6, about 8.7, about 8.8, about 8.9, about 9.0, about 9.1, about 9.2, about 9.3, about 9.4, about 9.5, about 9.6, about 9.7, about 9.8, about 9.9, about 10.0, about 10.1, about 10.2, about 10.3, about 10.4, about 10.5, about 10.6, about 10.7, about 10.8, about 10.9, about 11.0, about 11.1, about 11.2, about 11.3, about 11.4, about 11.5, about 11.6, about 11.7, about 11.8, about 11.9, about 12.0, about 12.1, about 12.2, about 12.3, about 12.4, about 12.5, about 12.6, about 12.7 , approximately 12.8, approximately 12.9, approximately 13.0, approximately 13.1, approximately 13.2, approximately 13.3, approximately 13.4, approximately 13.5, approximately 13.6, approximately 13.7, approximately 13.8, approximately 13.9, approximately 14.0, approximately 14.1, approximately 14.2, approximately 14.3, approximately 14.4, approximately 14.5, approximately 14.6, approximately 14.7, approximately 14.8, approximately 14.9, approximately 15.0, approximately 15.1, approximately 15.2, approximately 15.3, approximately 15.4, approximately 15.5, approximately 15.6, approximately 15.7, approximately 15.8, approximately 15.9, approximately 16.0, approximately 16.1, about 16.2, about 16.3, about 16.4, about 16.5, about 16.6, about 16.7, about 16.8, about 16.9, about 17.0, about 17.1, about 17.2, about 17.3, about 17.4, about 17.5, about 17.6, about 17.7, about 17.8, about 17.9, about 18.0, about 18.1, about 18.2, about 18.3, about 18.4, In some embodiments, the peroxide decomposition number, measured in minutes, is about 18.5, about 18.6, about 18.7, about 18.8, about 18.9, about 19.0, about 19.1, about 19.2, about 19.3, about 19.4, about 19.5, about 19.6, about 19.7, about 19.8, about 19.9, about 20.0, or any range formed from two or more of the above values ​​as range endpoints. In some embodiments, the peroxide decomposition number, measured in minutes, is about 10, about 15, about 20, about 25, about 30, about 35, about 40, about 45, or any range formed from two or more of the above values ​​as range endpoints.

[0102] The peroxide value is related to and correlates to the CDN and C1-DN, with each being a measure of the catalytic activity of the adsorbent. However, the correlation is not always precise, as each represents a different aspect of the adsorbent's catalytic activity. Furthermore, catalytic activity is only useful for the compounds being catalyzed; other compounds must be adsorbed to be effectively removed from the fluid stream. Therefore, a superior adsorbent will have superior performance in one or more of the CDN, C1-DN, peroxide value, and adsorption tests, and will therefore be able to effectively remove a wide range of compounds from the fluid stream.

[0103] Fluid Processing Another embodiment is directed to a method for purifying a fluid, e.g., water, by using the above-described chlorine and chloramine decomposition sorbents. In one embodiment, the fluid is treated by flowing the fluid over an adsorbent bed, introducing the fluid over a filter comprising the adsorbent, placing the adsorbent in a container for holding the fluid, or the like. In some embodiments, the above steps are combined in parallel or subsequently in series. In some embodiments, the fluid is water. In yet another embodiment, the fluid is water for consumption by humans, plants, animals, or marine life. In some embodiments, the fluid is in liquid form.

[0104] In other embodiments, the method for purifying a fluid includes additional steps. For example, in some embodiments, the method for purifying a fluid includes filtering the fluid, e.g., using a screen or sand filter, before, after, or both before and after contact with the adsorbent to remove particulates. In other embodiments, the method includes disinfecting the water to remove biological contaminants, e.g., bacteria or other microorganisms; in some embodiments, the method includes introducing a disinfectant into the fluid or irradiating the fluid with ultraviolet light. In yet other embodiments, the method includes purifying the fluid, adjusting the pH of the fluid, etc., and combinations thereof. In each of the above embodiments, the fluid may be water. [Example]

[0105] The following experimental examples are intended to better illustrate certain embodiments and are not intended to limit the disclosure. Example of a one-step process

[0106] Coconut carbonaceous material was supplied, processed, and activated. The resulting coconut activated carbon, available from Calgon Carbon Corporation under the product name OLC, is called precursor activated carbon. The coconut activated carbon is a granular activated carbon and is tested in a 12x40 size. The precursor activated carbon is oxidized in some tests but not others. After supplying the precursor activated carbon and possibly undergoing an optional oxidation step, the precursor activated carbon is ready to be doped with Cu, Fe, and N.

[0107] During Fe, Cu, and N doping, a one-step doping process is performed. The one-step doping process dopes oxidized or unoxidized precursor activated carbon with copper, iron, and nitrogen. During the one-step doping process, an aqueous solution containing CuSO4·5H2O, FeCl3·6H2O, and urea is contacted with the oxidized or unoxidized precursor activated carbon to obtain 0.2 wt% to 1.0 wt% Cu, 0.2 wt% to 1.0 wt% Fe, 2.2 wt% to 8.3 wt% N, and up to 15 wt% N, measured on the dry precursor activated carbon. The aqueous solution is contacted with the precursor activated carbon for up to 30 minutes at 25°C. After contacting the aqueous solution with the precursor activated carbon, the precursor activated carbon is dried, thereby producing the doped precursor activated carbon.

[0108] The doped precursor activated carbon is finally calcined, during which it is heated to a temperature of about 950°C for 1 hour under a pure N2 atmosphere.

[0109] Experimental results Figure 4 shows the effect of varying amounts of nitrogen doped into precursor activated carbon on CDN and peroxide values ​​while maintaining a total metal level of approximately 0.5 wt%. The results shown in Figure 4 are for a precursor activated carbon formed from coconut carbonaceous material and subsequently oxidized. This oxidized activated carbon was doped with Cu, Fe, and N. Figure 4 shows that for a total metal loading level of 0.5 wt%, the CDN and peroxide decomposition values ​​do not increase substantially after doping with approximately 4 wt% nitrogen.

[0110] Figures 5 and 6 demonstrate the effect of metal doping of precursor activated carbon on both the CDN and peroxide decomposition value of Cu-, Fe-, and N-doped oxidized precursor activated carbon prepared from coconut carbonaceous material. Doping such activated carbon precursors with Cu, Fe, and N results in higher CDN values ​​compared to doping precursor activated carbons formed from coconut carbonaceous material with Cu and N or Fe and N. Such Cu, Fe, and N doping also results in faster (and therefore superior) peroxide decomposition values ​​than doping with Cu and N or Fe and N.

[0111] Figure 7 shows a comparison of the effect of various amounts of nitrogen added to the oxidized precursor activated carbon on the CDN and peroxide decomposition numbers while maintaining total metal levels at approximately 0.5 wt% for Cu-N, Fe-N, and Cu-Fe-N.

[0112] Figure 8 shows the effect of varying amounts of nitrogen added to unoxidized precursor activated carbon on both the CDN and peroxide decomposition number of unoxidized precursor activated carbon formed from coconut carbonaceous material doped with Cu, Fe, and N while maintaining a total metal level of about 0.5 wt%. Figure 8 shows that for a total metal loading level of 0.5 wt%, the CDN increases linearly as more nitrogen is added to the carbon. The peroxide decomposition number also decreases as more nitrogen is added to the carbon.

[0113] Figures 9 and 10 show the effect of metal loading on both the CDN and peroxide decomposition rate of unoxidized precursor activated carbons formed from coconut doped with Cu, Fe, and N, respectively. Doping such unoxidized precursor activated carbons with Cu, Fe, and N results in higher CDN values ​​compared to unoxidized precursor activated carbons doped with Cu and N or Fe and N alone. Doping unoxidized precursor activated carbons formed from coconut carbonaceous material with Cu, Fe, and N results in faster peroxide decomposition rates compared to doping with Cu and N alone or Fe and N alone.

[0114] Table 1 shows a comparison between Cu-N, Fe-N, and Cu-Fe-N doped unoxidized activated carbons formed from wood carbonaceous materials. When a peroxide value is listed as ">60," it means that no temperature peak was observed after the 60-minute test period and the true peroxide value is for a period exceeding 60 minutes. This indicates a failure for this indicator. BGE is a granular wood-based activated carbon available from Calgon Carbon Corporation. AquaGuard® is a wood-based catalytic activated carbon for chlorine and chloramine removal in drinking water applications, available from Ingevity Corporation of North Charleston, South Carolina. [Table 1]

[0115] In the above detailed description, reference is made to the accompanying drawings, which form a part of this specification. In the drawings, like symbols typically identify like components unless the context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not intended to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are expressly contemplated herein.

[0116] The present disclosure is not limited with respect to the specific embodiments described in this application, which are intended as illustrative of various aspects. As will be apparent to those skilled in the art, many modifications and variations can be made without departing from the spirit and scope thereof. Functionally equivalent methods and apparatuses within the scope of the present disclosure, in addition to those recited herein, will be apparent to those skilled in the art from the foregoing description. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that the present disclosure is not limited to particular methods, reagents, compounds, compositions, or biological systems, as these may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0117] With respect to the use of virtually any plural and / or singular term herein, those skilled in the art can translate from the plural to the singular and / or from the singular to the plural as appropriate to the context and / or application. Various singular / plural arrangements may be expressly set forth herein for clarity.

[0118] Those skilled in the art will understand that the terms used herein, and particularly in the appended claims (e.g., the body of the appended claims), are generally intended as "open" terms in general terms (e.g., the term "including" should be interpreted as "including, but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "including, but not limited to," etc.). Although various compositions, methods, and devices are described in terms of "comprising" various components or steps (interpreted as meaning "including, but not limited to"), the compositions, methods, and devices can also "consist essentially of" or "consist of" the various components and steps, and such terminology should be interpreted as defining an essentially closed group of members. It will be further understood by those skilled in the art that where a specific number of recitations of the introduced claims are intended, such intention will be explicitly recited in the claim; in the absence of such recitation, no such intention exists.

[0119] For example, as an aid to understanding, the following appended claims may include the use of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed as implying that introducing a claim recitation with the indefinite article "a" or "an" limits a particular claim containing such an introduced claim recitation to embodiments containing only one of such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and an indefinite article such as "a" or "an" (e.g., "a" and / or "an" should be interpreted to mean "at least one" or "one or more"). The same applies to the use of specific articles used to introduce claim recitations.

[0120] Furthermore, even if a particular number of enumerations in the introduced claims are explicitly recited, those skilled in the art will recognize that such enumeration should be interpreted to mean at least the number recited (e.g., without other qualifiers, meaning at least two enumerations, or more than two enumerations, e.g., a bare enumeration and "two enumerations"). Furthermore, in those instances where a convention similar to "at least one of A, B, and C, etc." is used, generally, such structure is intended in the sense that one skilled in the art would understand the convention (e.g., "a system having at least one of A, B, and C" includes, but is not limited to, systems having A only, B only, C only, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). Moreover, in those instances where a convention similar to "at least one of A, B, or C, etc." is used, generally, such construction is intended in the sense that one of ordinary skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" includes, but is not limited to, systems having A only, B only, C only, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). It will be further understood by those of ordinary skill in the art that virtually any separate word and / or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibility of including that word, either of those words, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

[0121] Furthermore, when features or aspects of the present disclosure are described in terms of a Markush group, those skilled in the art will recognize that the present disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0122] As will be understood by those skilled in the art, for any and all purposes, including providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations thereof. A recited range can be readily recognized as fully descriptive and allowing for the same range to be divided into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily divided into lower, middle, and upper thirds, etc. Also, as will be understood by those skilled in the art, all language, such as "up to," "at least," etc., refers to a range that is inclusive of the recited numbers and can then be divided into subranges as discussed above. Finally, as will be understood by those skilled in the art, a range includes each individual member. Thus, for example, a group having 1 to 3 members refers to groups having 1, 2, or 3 members. Similarly, a group having 1 to 5 members refers to groups having 1, 2, 3, 4, or 5, etc.

[0123] Various of the above-described and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements may subsequently occur to those skilled in the art, each of which is also intended to be encompassed by the embodiments of the present disclosure.

Claims

1. 1. An adsorbent formed from a carbonaceous material that is activated to form a precursor activated carbon, the adsorbent comprising: 4% to 20% by weight of nitrogen, measured on the dry precursor activated carbon; 0.1% to 1% by weight of iron and 0.1% to 1% by weight of copper, measured on a dry precursor activated carbon basis; The weight ratio of the iron to the copper is 50:50; the adsorbent has a chloramine decomposition number (CDN) of 5 to 75, the CDN being the absolute value multiplied by 1000 of a first order linear kinetic fit applied to the natural logarithm of the chloramine concentration in water versus time, where the initial concentration of chloramine decreases over 150 minutes; and the adsorbent has a peroxide value of less than 20 minutes, the peroxide value being the time in minutes required for a buffer solution containing the adsorbent sample to reach 75% of the maximum recorded temperature; Adsorbent material.

2. 2. The adsorbent according to claim 1, wherein the chloramine decomposition value is 20 to 75.

3. 10. The adsorbent of claim 1, wherein the adsorbent has a peroxide value of less than 15 minutes.

4. 10. The adsorbent of claim 1, wherein the adsorbent has a peroxide value of from 1 minute to 10 minutes.

5. 2. The adsorbent of claim 1, wherein the amount of nitrogen is 4% to 10% by weight.

6. 2. The adsorbent of claim 1, wherein the amount of nitrogen is 10% to 20% by weight.

7. 10. The adsorbent of claim 1, wherein the adsorbent is formed from a carbonaceous material formed from one or more of coal, wood, and coconut.

8. 8. The adsorbent of claim 7, wherein at least a portion of said carbonaceous material is formed from coconut.

9. A method for making the adsorbent material of claim 1, comprising: providing a carbonaceous material; activating the carbonaceous material to form a precursor activated carbon; optionally oxidizing the precursor activated carbon; doping the precursor activated carbon by contacting the precursor activated carbon with one or more compounds that are a copper source, an iron source, and a nitrogen source, thereby forming a doped precursor activated carbon; and and calcining the doped precursor activated carbon by heating to a temperature of at least 950°C in a calcination atmosphere that does not cause any substantial oxidation or activation of the doped precursor activated carbon, thereby forming an adsorbent.

10. 10. The method of claim 9, wherein a single compound is the copper source, the iron source, and the nitrogen source.

11. 10. The method of claim 9, wherein a first compound is the copper source and the iron source, and a second compound is the nitrogen source.

12. 10. The method of claim 9, wherein a first compound is the copper source and the nitrogen source, and a second compound is the iron source.

13. 10. The method of claim 9, wherein a first compound is the iron source and the nitrogen source, and a second compound is the copper source.

14. 10. The method of claim 9, wherein a first compound is the copper source, a second compound is the iron source, and a third compound is the nitrogen source.

15. 10. The method of claim 9, wherein doping the precursor activated carbon is carried out in a one-step process comprising contacting the precursor activated carbon in an aqueous solution comprising the copper source, the iron source, and the nitrogen source.

16. The copper source is copper(II) sulfate pentahydrate (CuSO ４ ・5H ２ O), copper(II) chloride (CuCl ２ ), copper(II) chloride dihydrate (CuCl ２ ・2H ２ O), copper(II) nitrate (Cu(NO ３ ) ２ ), copper(II) nitrate monohydrate (Cu(NO ３ ) ２ ． H ２ O), copper(II) nitrate sesquihydrate (Cu(NO ３ ) ２ ． 1.5H ２ O), copper(II) nitrate hemipentahydrate (Cu(NO ３ ) ２ ． 2.5H ２ O), copper(II) nitrate trihydrate (Cu(NO ３ ) ２ ． 3H ２ O), copper(II) nitrate hexahydrate (([Cu(H ２ O) ６ ](NO ３ ) ２ )), copper(II) acetate (Cu(CH ３ COO) ２ ), copper(II) acetate monohydrate (Cu(CH ３ COO) ２ H ２ O), copper(II) formate tetrahydrate, Cu(NH ３ ) ６ ＋２ 、 Copper(II) hydroxide carbonate (Cu ２ (OH) ２ CO ３ ), compounds thereof, or mixtures thereof; The iron source is iron(III) chloride hexahydrate (FeCl ３ ・6H ２ O), iron(II) chloride tetrahydrate (FeCl ２ ・4H ２ O), ammonium iron(III) sulfate dodecahydrate (NH ４ Fe(SO ４ ) 12H ２ O), iron(II) sulfate heptahydrate (Fe ２ SO ４ ・7H ２ O), ammonium iron(III) oxalate trihydrate ((NH ４ ) ３ Fe(C ２ O ４ ) ３ ・3H ２ O), ammonium hexacyanoferrate(II) hydrate ((NH ４ ) ４ [Fe(CN) ６ ]・xH ２ O), ammonium iron(III) citrate ((NH ４ ) ５ [Fe(C ６ H ４ O ７ ) ２ ]), sodium ferrocyanide decahydrate (Na ４ Fe(CN) ６ ・10H ２ O), sodium ferric oxalate (Na ３ Fe(C ２ O ４ ) ３ ), potassium ferrocyanide trihydrate (K ４ [Fe(CN) ６ ]・3H ２ O), potassium ferricyanide (K ３ [Fe(CN) ６ ]), potassium ferrous oxalate (K ２ [Fe(C ２ O ４ ) ２ ]), or iron(II) acetate tetrahydrate ((CH ３ COO) ２ Fe 4H ２ O), iron lactate dihydrate, iron lactate trihydrate, compounds thereof, or mixtures thereof; 10. The method of claim 9, wherein the nitrogen source is one or more compounds in which the nitrogen has an oxidation state of −3.

17. Pre-sintering is N ２ 10. The method of claim 9, carried out at a temperature of 800°C to 1050°C in an atmosphere.

18. 10. The method of claim 9, wherein said oxidizing is necessary and performed.

19. 10. The method of claim 9, wherein said oxidizing is not performed.

20. The copper source is copper(II) sulfate pentahydrate (CuSO ４ ． 5H ２ O), wherein the iron source is iron(III) chloride hexahydrate (FeCl ３ ・6H ２ 17. The method of claim 16, wherein the nitrogen source is one or more of urea or dicyandiamide (DCD).

21. Pre-sintering is N ２ 10. The method of claim 9, carried out in an atmosphere at a temperature of 400°C to 1050°C.

22. Pre-sintering is N ２ 10. The method of claim 9, carried out in an atmosphere at a temperature of 925°C to 975°C.

23. 1. A method for removing chlorine, chloramines, or both chlorine and chloramines from a fluid, said method comprising: providing a sorbent, the sorbent formed from a carbonaceous material that is activated to form a precursor activated carbon, the sorbent comprising 4% to 20% by weight nitrogen, measured on a dry precursor activated carbon basis, and 0.1% to 1% by weight iron and 0.1% to 1% by weight copper, measured on a dry precursor activated carbon basis, wherein the weight ratio of the iron to the copper is 50:50; the sorbent having a chloramine decomposition number (CDN) of 5 to 75, the CDN being the absolute value multiplied by 1000 of a first-order linear kinetic fit applied to the natural logarithm of the chloramine concentration in water versus time, such that the initial concentration of chloramines decreases over 150 minutes; and the sorbent having a peroxide number of less than 20 minutes, the peroxide number being the time in minutes required for a buffer solution containing a sample of the sorbent to reach 75% of its maximum recorded temperature; contacting the adsorbent with a fluid; A method comprising:

24. 24. The method of claim 23, wherein the fluid is liquid water.

25. 24. The method of claim 23, wherein the water or the adsorbent has previously undergone a disinfection process.

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