Chemical adsorbent oxidation method and adsorbent produced thereby

Abstract

A sorbent material is described that has improved performance for removing chlorine and chloramines, among other toxic compounds. The sorbent material is formed by a process that includes oxidizing with an oxidizing agent, adding a nitrogen-containing compound, and calcining the sorbent. [Selection diagram] Figure 4

Description

Technical Field

[0001] Adsorbent materials having a high surface area and chemically modified to have catalytic properties are well known for their oxidation and decomposition properties. These properties are used in various fields, particularly for the removal and destruction of chlorine, chloramines, trihalomethanes, haloacetic acids, and hydrogen peroxide formed when water is disinfected. Adsorbent materials are typically formed from various activated carbons and carbonaceous chars that are heat-treated with a nitrogen-containing precursor and subsequently activated and / or oxidized to produce catalytic activated carbon. Alternatively, the nitrogen-containing precursor can be carbonized and activated. Activation and / or oxidation are usually carried out at high temperature using an activation gas such as steam (water), carbon dioxide, or oxygen. These methods are described in several U.S. patents, including U.S. Patent No. 6,342,129, U.S. Patent No. 6,706,194, U.S. Patent No. 5,356,849, U.S. Patent No. 5,338,458, and U.S. Patent No. 9,174,205, all of which are incorporated herein by reference in their entirety.

Background Art

[0002] Conventional nitrogen pretreatment and activation and / or oxidation techniques have drawbacks. The activation and / or oxidation process gasifies the surface portion of the carbonaceous char or other sorbent material, resulting in the formation of small pores when carbon or other materials on the surface of the adsorbent particles vaporize. These pores cause the high total surface area of the adsorbent material and contribute to its high performance. However, this gasification during the activation process is not selective for the materials removed from the surface because various forms of oxygen (air, pure O 2 , dissociated oxygen from steam, dissociated oxygen from CO 2 , etc.) at high temperature are strong carbon gasification and oxidizing agents. As a result, much of the incorporated nitrogen that is involved in the catalytic activity and is part of the surface skeleton of the adsorbent material is removed during the activation and / or oxidation process. This is a reverse effect, reducing the catalytic properties of the adsorbent material and its performance in the removal and destruction of harmful compounds from water.

[0003] Claiming priority to U.S. Provisional Application No. 62 / 458,371, filed on February 13, 2017, U.S. Patent Application Publication No. 2018 / 0229217, filed on February 13, 2018, discloses an improved process for treating adsorbent materials. Both of these disclosures are hereby incorporated by reference in their entirety.

[0004] Improvements in various steps of forming adsorbent materials continue to be needed. The present invention provides these improvements in a novel process. In particular, this specification is directed to an improved process for the chemical oxidation of adsorbents. The prior art document information related to the invention of this application is as follows (including documents cited during the international phase after the international filing date and documents cited when entering the national phase in other countries). (Prior Art Document) (Patent Document) (Patent Document 1) U.S. Patent No. 5,504,050 (Patent Document 2) U.S. Patent Application Publication No. 2012 / 0220451 (Patent Document 3) U.S. Patent Application Publication No. 2003 / 0209498 (Patent Document 4) U.S. Patent Application Publication No. 2008 / 0073290 (Patent Document 5) U.S. Patent Application Publication No. 2008 / 0161183 (Patent Document 6) U.S. Patent Application Publication No. 2011 / 0076210 (Patent Document 7) U.S. Patent Application Publication No. 2013 / 0023405 (Patent Document 8) U.S. Patent Application Publication No. 2014 / 0013942 (Patent Document 9) U.S. Patent Application Publication No. 2016 / 0023920 (Patent Document 10) U.S. Patent Application Publication No. 2016 / 0236169 (Patent Document 11) U.S. Patent Application Publication No. 2016 / 0346723 (Patent Document 12) U.S. Patent Application Publication No. 2019 / 0201870 (Patent Document 13) U.S. Patent No. 4,624,937 (Patent Document 14) U.S. Patent No. 4,921,826 (Patent Document 15) U.S. Patent No. 5,338,458 (Patent Document 16) U.S. Patent No. 5,356,849 (Patent Document 17) U.S. Patent No. 6,342,129 (Patent Document 18) U.S. Patent No. 6,706,194 (Patent Document 19) U.S. Patent No. 7,361,280 (Patent Document 20) U.S. Patent No. 7,923,410 (Patent Document 21) U.S. Patent No. 9,120,079 (Patent Document 22) U.S. Patent No. 9,120,079 (Patent Document 23) U.S. Patent No. 9,174,205 (Patent Document 24) Canadian Patent Application Publication No. 2485103 (Patent Document 25) Chinese Patent Application Publication No. 102553641 (Patent Document 26) Chinese Patent Application Publication No. 103626150 (Patent Document 27) German Patent Invention No. 3620425 (Patent Document 28) Japanese Unexamined Patent Application Publication No. 01-058331 (Patent Document 29) International Publication No. 2014164275 (Non-Patent Document) (Non-Patent Document 1) Sharifi et al. "Formation of Active Sites for Oxygen Reduction Reactions by Transformation of Nitrogen Functionalities in Nitrogen-Doped Carbon Nanotubes." ACS Nano, vol. 6, no. 10, 2012, pp. 8904 - 8912, doi:10.1021 / nn302906r (Non-Patent Document 2) "The Chemistry of Nitrogen and Phosphorous." Purdue Chemistry, Purdue University. (2006). chemed.chem.purdue.edu / genchem / topicreview / bp / ch10 / group5.php#negative. (Non-Patent Document 3) Extended European Search Report for EP Application No. 19754189.9 dated October 18, 2021 (Non-Patent Document 4) International Search Report and Written Opinion for PCT / US2018 / 017973 dated May 29, 2018 (Non-Patent Document 5) International Search Report and Written Opinion for PCTUS2019 / 17878 dated June 6, 2019 (Non-Patent Document 6) SEREDYCH et al., "Surface functional groups of carbons and the effects of their chemical character, density and accessibility to ions on electrochemical performance", Carbon, September 2008, Vol. 46(11):1475 - 1488 (Non-Patent Document 7) Supplementary European Search Report for European Patent Application No. 18 751 323.9 dated November 23, 2020

SUMMARY OF THE INVENTION

[0005] The present invention discloses a method for manufacturing an adsorbent, as well as an adsorbent manufactured by the process of the present invention. The present invention further discloses a filter assembly formed by including the adsorbent disclosed herein.

[0006] One embodiment is a method for manufacturing an adsorbent material product, the method comprising providing an adsorbent material raw material, oxidizing the adsorbent material raw material with an oxidizing agent, wherein the oxidizing agent is selected from the group consisting of nitric acid, potassium peroxymonosulfate, potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, peracetic acid, acetic acid, calcium hypochlorite, sodium hypochlorite, hypochlorous acid, benzoyl peroxide, sodium percarbonate, sodium perborate, organic peroxides, organic hydroperoxides, bleaching compounds, peroxide-based bleaching agents, chlorine-based bleaching agents, a mixture of hydrogen peroxide and urea, a mixture of peracetic acid and urea, and combinations thereof, oxidizing, adding a nitrogen-containing precursor to the oxidized adsorbent material raw material, wherein the nitrogen-containing precursor is a reduced nitrogen compound, adding, and heating the oxidized adsorbent material raw material and the nitrogen-containing precursor to a temperature of at least about 400°C in an inert atmosphere to form an adsorbent material product.

[0007] In another embodiment, the adsorbent material product has a chloramine destruction number (CDN) of at least about 2.0, where the CDN is 1000 times the absolute value of the first-order linear kinetics fit, and is applied to the natural logarithm of the chloramine concentration in water and the time when the initial concentration of chloramine decreases over 150 minutes.

[0008] In another embodiment, the adsorbent material product has a CDN of at least about 5.0.

[0009] In another embodiment, the adsorbent material product has a CDN of from about 10.0 to about 60.0.

[0010] In another embodiment, the adsorbent material product has a chlorine destruction number (C1-DN) of at least about 80.0, where the C1-DN is 1000 times the absolute value of the first-order linear kinetics fit, and is applied to the natural logarithm of the chlorine concentration in water and the time when the initial concentration of chlorine decreases over 150 minutes.

[0011] In another embodiment, the C1-DN value is from about 80.0 to about 250.0.

[0012] In another embodiment, the formed adsorbent has a nitrogen edge concentration of at least about 0.20 atomic %.

[0013] In another embodiment, the adsorbent material product has a nitrogen edge concentration of from about 0.20 atomic % to about 2.0 atomic %.

[0014] In another embodiment, the nitrogen-containing precursor has an oxidation state of -3.

[0015] In another embodiment, the adsorbent material raw material includes at least one of activated carbon, reactivated carbon, activated coke, and combinations thereof.

[0016] In another embodiment, heating the oxidized adsorbent material feedstock and the nitrogen-containing precursor is to at least 700 °C under an inert atmosphere, thereby forming an adsorbent material product.

[0017] In one embodiment, the adsorbent material product has a nitrogen edge concentration of at least about 0.20 atomic % and a chloramine destruction number (CDN) of at least about 2.0, where the CDN is 1000 times the absolute value of the first-order linear kinetics fit and is applied to the natural logarithm of the chloramine concentration in water and the time when the initial concentration of chloramine decreased over 150 minutes.

[0018] Another embodiment provides a method comprising providing an adsorbent material feedstock, oxidizing the adsorbent material feedstock with an oxidizing agent selected from the group consisting of nitric acid, potassium peroxymonosulfate, potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, peracetic acid, acetic acid, calcium hypochlorite, sodium hypochlorite, hypochlorous acid, benzoyl peroxide, sodium percarbonate, sodium perborate, organic peroxides, organic hydroperoxides, bleaching compounds, peroxide-based bleaching agents, chlorine-based bleaching agents, a mixture of hydrogen peroxide and urea, a mixture of peracetic acid and urea, and combinations thereof, adding a nitrogen-containing precursor to the oxidized adsorbent material feedstock, wherein the nitrogen-containing precursor is a reduced nitrogen compound, and heating the oxidized adsorbent material feedstock and the nitrogen-containing precursor to a temperature of at least about 400 °C under an inert atmosphere to form an adsorbent material product.

[0019] In another embodiment, the adsorbent material product has a CDN of from about 10.0 to about 60.0.

[0020] In another embodiment, the adsorbent material product has a CDN of at least about 5.0.

[0021] In another embodiment, the adsorbent material product has a chlorine destruction number (C1-DN) of at least about 80.0, where C1-DN is 1000 multiplied by the absolute value of the first-order linear kinetics fit, and is applied to the natural logarithm of the chlorine concentration in water and the time when the initial concentration of chlorine decreased over 150 minutes.

[0022] In another embodiment, the C1-DN value is from about 80.0 to about 250.0.

[0023] In another embodiment, the adsorbent material product has a nitrogen edge concentration of from about 0.20 atomic % to about 2.0 atomic %.

[0024] In another embodiment, the nitrogen-containing precursor has an oxidation state of -3.

[0025] In another embodiment, the adsorbent material product comprises an adsorbent material raw material that is at least one of activated carbon, reactivated carbon, activated coke, and combinations thereof.

[0026] In another embodiment, the step of heating the oxidized adsorbent material raw material and the nitrogen-containing precursor is heating to a temperature of at least 700 °C under an inert atmosphere, thereby forming the adsorbent material product.

[0027] One embodiment is a filter device comprising an adsorbent material product having a nitrogen edge concentration of at least about 0.20 atomic % and a chloramine destruction number (CDN) of at least about 2.0, where CDN is 1000 multiplied by the absolute value of the first-order linear kinetics fit, and is applied to the natural logarithm of the chloramine concentration in water and the time when the initial concentration of chloramine decreased over 150 minutes.

[0028] Another embodiment includes a step of providing an adsorbent material raw material, and a step of oxidizing the adsorbent material raw material with an oxidizing agent, where the oxidizing agent is selected from the group consisting of nitric acid, potassium peroxymonosulfate, potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, peracetic acid, acetic acid, calcium hypochlorite, sodium hypochlorite, hypochlorous acid, benzoyl peroxide, sodium percarbonate, sodium perborate, organic peroxides, organic hydroperoxides, bleaching compounds, peroxide-based bleaching agents, chlorine-based bleaching agents, a mixture of hydrogen peroxide and urea, a mixture of peracetic acid and urea, and combinations thereof; an oxidizing step; a step of adding a nitrogen-containing precursor to the oxidized adsorbent material raw material, where the nitrogen-containing precursor is a reduced nitrogen compound; an adding step; and a step of heating the oxidized adsorbent material raw material and the nitrogen-containing precursor to a temperature of at least about 400° C. in an inert atmosphere to form an adsorbent material product. The adsorbent material product is formed by a method having these steps.

[0029] In another embodiment, the adsorbent material product includes an adsorbent material raw material that is at least one of activated carbon, reactivated carbon, activated coke, and combinations thereof.

[0030] In another embodiment, the filter device further has at least one of a binder or a filler, or at least one or more additional adsorbent materials.

[0031] In another embodiment, the adsorbent material product is included in a filter device as particles, a solid monolith, a block, an extruded shape, a molded shape, a pressed shape, a roll substrate or sheet, a flat substrate or sheet, a spunbond shape, or a wet molded shape formed from a fiber slurry, or is included in a plurality of the aforementioned structures.

[0032] In another embodiment, heating the oxidized adsorbent material raw material and the nitrogen-containing precursor is up to a temperature of at least 700° C. in an inert atmosphere, thereby forming the adsorbent material product.

[0033] In another embodiment, the adsorbent material product has a CDN of at least about 5.0.

[0034] One embodiment is a method of treating a liquid, the method comprising contacting the liquid with an adsorbent material product having a nitrogen edge concentration of at least about 0.20 atomic % and a chloramine destruction number (CDN) of at least about 2.0, where the CDN is 1000 multiplied by the absolute value of the first order linear kinetics fit and is applied to the natural logarithm of the chloramine concentration in water and the time when the initial concentration of chloramine has decreased over 150 minutes.

[0035] In another embodiment, the adsorbent material product has a CDN of at least about 5.0.

Brief Description of the Drawings

[0036]

Figure 1

Modes for Carrying Out the Invention

[0037] Before the compositions and methods of the present invention are described, it should be understood that these are subject to change and that the present invention is not limited to the specific methods, compositions, or methodologies described. Also, the terminology used in the description is for the purpose of describing only particular versions or embodiments and is not intended to limit the scope of the present invention, which is limited only by the appended claims. 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. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, the preferred methods, devices, and materials are described herein. All publications mentioned herein are incorporated by reference in their entirety. In this specification, it should not be construed that the present invention admits a right to precedence over such disclosure by virtue of prior invention.

[0038] As used in this specification and the appended claims, it should also be noted that the singular forms "a", "an", and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, a reference to "a combustion chamber" is a reference to "one or more combustion chambers" and equivalents thereof known to those skilled in the art.

[0039] As used herein, the term "about" means plus or minus 10% of the numerical value of the number in which it is used. Thus, about 50% means in the range of 45% to 55%.

[0040] As used herein, the term "adsorbent" means any material exhibiting adsorption characteristics, absorption characteristics, or a combination of adsorption and absorption characteristics. Adsorption characteristics mean that atoms, ions, or molecules adhere to the surface of the adsorbent material. Absorption characteristics mean that atoms, ions, or molecules enter the bulk phase of the absorbent material and are retained therein.

[0041] As used herein, the term "adsorbent raw material" means any material that is untreated or substantially untreated and can be processed to form a material exhibiting adsorbent properties.

[0042] As used herein, the term "adsorbent intermediate material" means any adsorbent material or adsorbent raw material that has undergone at least one processing step.

[0043] As used herein, the term "adsorbent material raw material" means any material that can be used to form any adsorbent. The adsorbent material raw material is not limited and includes one or more of the adsorbent raw material and the adsorbent intermediate material.

[0044] As used herein, the term "adsorbent material product" means any material exhibiting adsorbent properties after at least one processing step of the adsorbent material raw material.

[0045] As used herein, the term "reduced nitrogen" means any nitrogen-containing molecule or nitrogen-containing compound in which nitrogen has an oxidation state of -3.

[0046] In some embodiments, the present specification discloses compositions for removing chloramine, chlorine, peroxide, and other harmful compounds using an adsorbent, as well as methods for manufacturing such adsorbents. In other embodiments, the present invention discloses devices and instruments such as filters containing a catalytic adsorbent material. The devices and instruments include water filters and liquid filters. In other embodiments, the present invention is directed to methods of using these devices and instruments for removing harmful compounds such as chloramine, chlorine, and peroxide.

[0047] Embodiments include a method for making an adsorbent material product and an adsorbent prepared by such a method. The method can include a step of oxidizing an adsorbent raw material. The step of oxidizing the adsorbent material raw material can be performed before adding a nitrogen-containing precursor. The oxidizing step can be carried out by various techniques. In some embodiments, the oxidizing step includes contacting the adsorbent raw material with an oxidizing agent. In some embodiments, the oxidizing agent includes at least one of nitric acid, potassium peroxymonosulfate, potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, peracetic acid, acetic acid, calcium hypochlorite, sodium hypochlorite, hypochlorous acid, benzoyl peroxide, sodium percarbonate, sodium perborate, organic peroxides, organic hydroperoxides, bleaching compounds, peroxide-based bleaching agents, chlorine-based bleaching agents, a mixture of hydrogen peroxide and urea, a mixture of peracetic acid and urea, and at least one combination of one or more of the above.

[0048] In some embodiments, the oxidizing step includes heating or otherwise treating the feed sorbent material and the chemical oxidant or oxidizing agent. In such embodiments, the heating step includes heating the feed sorbent material and the oxidizing agent to a temperature of about 25° C., about 50° C., about 75° C., about 100° C., about 125° C., about 150° C., about 175° C., about 200° C., about 225° C., about 250° C., about 275° C., about 300° C., about 325° C., about 350° C., about 375° C., about 400° C., and a range formed by a combination of any two of the above values. In some embodiments, the heating step is performed at any range with the above temperature values ​​being the lower end of the range, i.e., the heating is performed at at least about 25°C, at least about 50°C, at least about 100°C, at least about 125°C, at least about 150°C, at least about 175°C, at least about 200°C, at least about 225°C, at least about 250°C, at least about 275°C, at least about 300°C, at least about 325°C, at least about 350°C, at least about 375°C, at least about 400°C, or any combination of one or more of the aforementioned ranges. In yet another embodiment, the oxidation step is a non-thermal process and is performed without applying external heat to the mixture of oxidant and / or sorbent feedstock.

[0049] In some embodiments, multiple oxidation steps are performed on the sorbent material feedstock. The sorbent material feedstock includes one or more of the sorbent feedstock or the sorbent intermediate material. The number of oxidation steps is not limited and can be at least one oxidation step, at least two oxidation steps, at least three oxidation steps, or at least four oxidation steps. These steps are designated as a first oxidation step, a second oxidation step, a third oxidation step, a fourth oxidation step, etc. The above steps of contacting the sorbent feedstock with an oxidizing agent are in some embodiments combined with a step of oxidizing the sorbent feedstock under certain atmospheric conditions as described below.

[0050] Additional step or steps of oxidizing the adsorbent material under a particular atmosphere includes one or more of a particular atmospheric temperature, a particular atmospheric composition, or a particular atmospheric pressure. In some embodiments, the combined steps of the additional oxidation process are carried out by exposing the adsorbent material to an oxygen-containing environment and heating the material to a temperature of from about 150°C to about 1050°C. In some embodiments, the temperature of oxidation is from about 150°C to about 250°C, from about 250°C to about 350°C, from about 350°C to about 450°C, from about 450°C to about 550°C, from about 550°C to about 650°C, from about 650°C to about 750°C, from about 750°C to about 850°C, from about 850°C to about 950°C, from about 950°C to about 1050°C, or any of these disclosed endpoints, or a range consisting of any combination of the above ranges or values within those ranges.

[0051] In other embodiments, the oxidation step is carried out in an oxygen-containing environment including air, oxygen, steam, ozone, oxygen plasma, nitrogen oxide, and hydrogen peroxide, carbon dioxide, an inert gas, a noble gas, or any arbitrary combination of one or more of the above. The adsorbent material raw material is in contact with or disposed within the above oxygen-containing environment. The amount of oxygen is not limited. In some embodiments, the amount of oxygen is about 5 vol%, about 10 vol%, about 15 vol%, about 20 vol%, about 20.95 vol% (i.e., air), about 25 vol%, about 30 vol%, about 35 vol%, about 40 vol%, about 45 vol%, about 50 vol%, about 55 vol%, about 60 vol%, about 65 vol%, about 70 vol%, about 75 vol%, about 80 vol%, about 85 vol%, about 90 vol%, about 95 vol%, or about 100 vol% (i.e., pure oxygen). The amount of oxygen can be any combination of one or more of the above values to form a range. In some embodiments, the range is from about 0 vol% to about 20 vol%, from about 0 vol% to about 20.95 vol%, from about 20 vol% to about 40 vol%, from about 40 vol% to about 60 vol%, from about 60 vol% to about 80 vol%, or from about 80 vol% to about 100 vol%.

[0052] In some embodiments, the oxygen-containing environment is dry, containing no moisture or substantially no measurable moisture. In other embodiments, the oxidation environment of any of the above compounds can also be humidified. The level of humidification can be from about 10 - 20%, about 20 - 40%, about 40 - 60%, about 60 - 80%, about 80 - 100%, about 100% or saturated, or values and ranges obtained from any combination of the above endpoints or ranges.

[0053] In some embodiments, the oxidation is achieved by a non-thermal process. In such embodiments, the adsorbent is oxidized by contacting the adsorbent with an oxidizing acid such as hydrogen peroxide, ozone, chlorine, persulfate, percarbonate, nitric acid, or any combination thereof in the liquid or vapor phase at a temperature below about 100°C. Some adsorbents containing carbon oxidize slowly in the presence of air at room temperature, with or without moisture, and although this oxidation is slow, it is ultimately sufficient to produce the oxidized adsorbent precursor. In some embodiments, the oxidation step is omitted, i.e., the adsorbent material raw material is not oxidized in a process faster than the above-mentioned slow oxidation that occurs naturally at room temperature under normal conditions.

[0054] The adsorbent material raw material of the embodiments of the present disclosure is not limited and can be any material known in the art. In some embodiments, the adsorbent material raw material is an adsorbent raw material. The adsorbent raw material is not limited and includes carbonaceous materials, carbon black, bituminous coal, sub-bituminous coal, lignite, anthracite, peat, nut shells, pits, coconut shells, babassu nuts, macadamia nuts, dendê nuts, peach pits, cherry pits, olive pits, walnut shells, wood, lignin, polymers, nitrogen-containing polymers, resins, nitrogen-containing resins, petroleum pitch, bagasse, rice husks, corn husks, wheat husks and rice husks, graphene, carbon nanotubes, graphite, zeolites, silica, silica gel, alumina clay, diatomaceous earth, metal oxides, molecular sieves, or any combination of the listed materials. In some embodiments, the adsorbent material raw material is an adsorbent intermediate material. The adsorbent intermediate material is not limited and includes one or more of activated carbon, reactivated carbon, or activated coke. In some embodiments, the adsorbent material raw material is provided in a pre-oxidized state. For example, the adsorbent raw material can be an adsorbent intermediate product that is oxidized. In other embodiments, the adsorbent material raw material is provided in a non-oxidized state. For example, the adsorbent raw material can be an unoxidized adsorbent intermediate product or an adsorbent raw material.

[0055] In some embodiments, after the oxidation is complete, the adsorbent intermediate product is contacted with a reduced nitrogen-containing compound. As described above, the term "reduced nitrogen" means any nitrogen-containing molecule or nitrogen-containing compound in which nitrogen has an oxidation state of -3. Reduced nitrogen-containing compounds include one or more of ammonia, ammonium salts, ammonium carbonate and bicarbonate, ammonium thiocyanate, azodicarbonamide, diammonium phosphate, dicyandiamide, guanidine hydrochloride, guanidine thiocyanate, guanine, melamine, thiourea, and urea. The contacting step can be performed by any method. For example, the step of contacting the adsorbent intermediate can be achieved by a step of dry mixing the adsorbent intermediate with the reduced nitrogen-containing compound, a step of impregnating the adsorbent intermediate with a solution of the reduced nitrogen-containing compound, or a step of contacting the adsorbent intermediate with a gaseous reduced nitrogen-containing compound.

[0056] In other embodiments, the nitrogen source can be the adsorbent material raw material itself, alone or in combination with additional reduced nitrogen-containing raw materials. Such nitrogen-containing raw materials are not limited. Examples of nitrogen-containing raw materials include one or more of nitrogen-containing monomers and nitrogen-containing polymers. In some embodiments, the nitrogen-containing raw material is a monomer, oligomer, or polymer of acrylonitrile, polyacrylonitrile, urethane, polyurethane, amide, polyamide, nitrile rubber, and combinations of one or more thereof. When nitrogen-containing raw materials are selected, they can be combined with the disclosed process of adding additional nitrogen precursors, or they can be used alone, omitting the further step of adding nitrogen precursors. In some alternative embodiments, the adsorbent intermediate material produced by the activation of the nitrogen-containing raw material is mixed with other adsorbent intermediate materials or other adsorbents treated in accordance with the present invention, instead of mixing with other untreated adsorbents.

[0057] In some embodiments, the adsorbent material precursor is calcined by heating to a temperature greater than about 400 °C before, during, or both before and during exposure to the nitrogen-containing compound. In some embodiments, the adsorbent material precursor is calcined by heating to a temperature greater than about 700 °C before, during, or both before and during exposure to the nitrogen-containing compound. In some embodiments, the heating is performed after contacting the precursor with the nitrogen-containing compound. Calcination is generally performed by heating the adsorbent precursor or adsorbent intermediate to a temperature sufficient to reduce the presence of surface oxides on the adsorbent precursor or adsorbent intermediate. The temperature at which the surface oxides are removed can be from about 400 °C to about 1050 °C, from about 400 °C to about 1000 °C, from about 600 °C to about 1050 °C, from about 800 °C to about 1050 °C, from about 850 °C to about 950 °C, or any temperature range that incorporates the above endpoints or is within the range of the above ranges. The temperature of the heating and / or calcination can be about 350 °C, 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, about 1100 °C, about 1150 °C, about 1200 °C, or a range formed by any two of these values as endpoints. The calcination process atmosphere can include an inert nitrogen gas or a noble gas such as helium, argon, neon, krypton, xenon, and radon. The heating and / or calcination can be performed over a period of about 1 to about 120 minutes. After heating and / or calcination, the resulting adsorbent intermediate or adsorbent material product may be cooled in an inert and / or noble gas atmosphere.

[0058] In certain embodiments, the adsorbent intermediate product or adsorbent material product can be prepared by repeating various steps of the above process. For example, each step of oxidation, exposure to nitrogen-containing compounds, or calcination can be repeated 1, 2, 3, 4, 5, or 6 times after the first such step of oxidation, exposure to nitrogen-containing compounds, or calcination. In some embodiments, the steps of calcination, activation, and inert cooling can each be individually repeated 1, 2, 3, 4, 5, or 6 times after the first such step of calcination, activation, or inert cooling. Alternatively, any other method known to generate catalytic activity in the high-temperature adsorbent material raw material can be applied to the resulting product to further enhance its catalytic activity. The step of gas or oxygen-based oxidation can be further combined with the step of liquid or chemical-based oxidation. For example, oxidation in peracetic acid can be carried out after the oxidation step in air.

[0059] In some embodiments, the adsorbent intermediate materials are processed to make them suitable for their intended use. Such additional processing steps for the adsorbent intermediate materials are not limited and include, for example, grinding, dry mixing, impregnation, sorting, grading, screening, briquetting, or agglomeration of the adsorbent intermediate materials. The additional steps can be carried out at any point during the process and can be repeated for individual steps or specific steps.

[0060] In some embodiments, the adsorbent material product has an average particle diameter (MPD) of about 4 mm or less. In certain embodiments, the sorbent material product has an MPD formed from about 1 μm to about 4 mm, about 100 μm to about 4 mm, about 0.1 mm to about 4 mm, about 0.5 mm to about 4 mm, about 1.0 mm to about 4 mm, about 4.0 μm to about 1.5 mm, about 2.0 μm to about 3.5 mm, about 1 μm to about 3 mm, a partial range included in any of these ranges, or a range formed from a combination of the endpoints of these ranges. The pore shape of the adsorbent can vary depending on the embodiment, and the adsorbent can have a pore distribution including macropores (diameter greater than 50 nm), mesopores (diameter 2 nm to 50 nm), and micropores (diameter less than 2 nm).

[0061] The pore size distribution can affect the type of material that can be adsorbed by the adsorbent. Particularly in the case of hydrocarbon molecules, the tendency for molecules to be adsorbed by activated carbon depends on the pore size. Thus, the pore size and the distribution of pore sizes can be selected to determine which chemical species will or will not be adsorbed by the adsorbent. A narrow pore size distribution can be used to adsorb only a few selected contaminants, while a wide pore size distribution can adsorb a variety of compounds.

[0062] The adsorbent material products described above are useful in water purification systems, particularly in water purification systems used for purifying drinking water. Yet another embodiment of the present disclosure is directed to filter devices such as, for example, filters, filter cartridges, beds, and particulate or powdered carbon, where the adsorbent material products described above are included. One or more of the above filter devices can be used in combination.

[0063] Filter devices, particularly consumer filters in various embodiments, can have any design and can include at least a housing, the housing including a compartment configured to hold the adsorbent material products of the present disclosure. The form of the adsorbent material products is not limited and includes at least one of a granulated structure, a powdered structure, a solid structure, a porous structure, and combinations thereof. These various forms can be used for adsorbent products including activated carbon and other adsorbent products.

[0064] In some embodiments, the adsorbent material product used in the filter device is provided in the form of a solid monolith, block, extruded shape, molded shape, pressed shape, roll substrate or sheet, flat substrate or sheet, spunbond shape, or wet molded shape formed from a fiber slurry, or a combination thereof. Each of the above is formed from an adsorbent material product, or a mixture of an adsorbent intermediate material and a binder or filler. The binder is not limited and includes at least one of a polymer, an adhesive, a carbonizable material, and combinations thereof, and generates a solid structure with the adsorbent material. Examples of binder materials include polyolefins, polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polyvinyl acetate, acrylics and acrylates, nylon and other polyesters, acrylonitrile, and combinations of one or more of these. The filler is not limited and includes oxides, ceramics, clays, and minerals.

[0065] In some embodiments, the filter device includes additional components such as, for example, a screen or other means for holding activated carbon within a compartment, or an additional purification device such as a filtration membrane. In some embodiments, the housing may include various components necessary to enable incorporation of the filter into a device such as a pitcher or bottle device through which water flows from one compartment to another and passes through the filter during transfer, a device attached to a water pipe or faucet that causes water to pass through the filter before being discharged from the faucet, or various components necessary to enable delivery to a water distribution device. In particular, the filter device may include an inlet port for introducing water into the filter and an outlet port for distributing filtered or treated water from the filter. In some embodiments, the filter device can include removable connection means for connecting to a water source such as a sink pipe, hose, pipe fitting, faucet, water jet, etc. at the inlet.

[0066] It should be noted that within the filter device or when supplied in bulk, the adsorbent material product or adsorbent intermediate material of the present disclosure can be mixed with other adsorbent materials. Such mixing can occur during the manufacture of the adsorbent material itself or during the manufacture of the filter device. In some embodiments, the adsorbent material product or adsorbent intermediate material of the present disclosure is mixed within a manufacturing apparatus for manufacturing the filter device, such as within an extrusion apparatus or an injection molding apparatus. In some embodiments, the adsorbent material product or adsorbent intermediate material of the present disclosure is blended with other sorbent materials provided for removing the same compounds (i.e., chloramine and chlorine) or other compounds. Other contaminants to be removed include nitrates, lead, mercury, arsenic, and organic compounds.

[0067] In some embodiments, the filter device can include a filter housing having an elongated envelope made of an inert plastic material such as polystyrene, polyethylene, polypropylene, polyvinyl chloride, polytetrafluoroethylene, polyethylene terephthalate, silicone, cross-linked polyethylene (PEX), or any combination thereof, disposed within the filter housing to hold low-contact pH activated carbon or a mixture of low-contact pH activated carbon and neutral activated carbon. The filter housing can also be made of any suitable metal such as aluminum, steel, stainless steel, titanium, magnesium, and combinations thereof. The filter housing can also be formed of a metallized plastic, for example, electroplated or electroless plated or vapor-deposited aluminum, steel, stainless steel, titanium, magnesium, chromium, and any of the above polymers having combinations thereof. The filter housing and the envelope can be spaced apart from each other, and in some embodiments, a particulate filter such as filter paper can be disposed within the space to hold dust associated with the activated carbon. In certain embodiments, an additional adsorbent such as carbon cloth can be disposed within the space. In some embodiments, the filter can include a perforated plate, a grooved grid, a mesh grill, a screen, or other means for securing the envelope within the housing while allowing free flow of fluid through the housing.

[0068] In some embodiments, the adsorbent material feedstock that has been processed in accordance with the present invention to form an adsorbent intermediate material may be mixed with other adsorbent material feedstocks (i.e., adsorbent feedstock) that have not been processed by the process of the present invention. The adsorbent material feedstock, the adsorbent intermediate product, and the adsorbent feedstock are the same as those disclosed above.

[0069] The amount of untreated adsorbent raw material mixed with the adsorbent intermediate product of the present disclosure can be any amount useful for achieving the desired final performance. The amount of untreated adsorbent raw material can be about 5 to 95 wt%, about 20 to 95 wt%, about 40 to 95 wt%, about 60 to 95 wt%, about 80 to 95 wt%, or any combination of the previously described ranges, based on 100% of the total mixture of treated and untreated adsorbent raw materials. In some embodiments, the amount of untreated adsorbent can be about 10 wt%, about 20 wt%, about 30 wt%, about 40 wt%, about 50 wt%, about 60 wt%, about 70 wt%, about 80 wt%, about 90 wt%, or about 95 wt% based on 100 wt% of the total composition. At least two of the above amounts can be combined to form the endpoints of the range.

[0070] Commercial or municipal water treatment devices can include larger filter devices or tanks designed to be attached to large high-flow water pipes that provide beds arranged to receive water from natural sources during processing. Such devices are well known in the art, and chlorine and chloramine that destroy activated carbon can be included in any such device. In some embodiments, beds or tanks containing granular activated carbon can be placed at various locations along the flow path of the treatment plant, and the chlorine and chloramine-destroying activated carbon described above can be used in any or all of these beds or tanks. In certain embodiments, the water may contact the adsorbent material product at one or more locations within the treatment path, and in such embodiments, the adsorbent material product may be a chlorine and chloramine-destroying adsorbent material product. As described above, in such treatment devices, granular or powdered chlorine and chloramine-decomposing adsorbent products can be used alone or in a mixture of chlorine and chloramine-decomposing adsorbent products and non-chlorine and non-chloramine-destroying adsorbent products. The treatment devices and facilities can include additional tanks and components such as, for example, equalization tanks, clarifiers, biological treatment tanks or tanks, sand filtration devices, membrane filtration devices, etc. and combinations thereof. Alternatively, the treatment facility can include an adsorbent holding tank where powdered activated carbon is added to the water being treated and then collected after adsorption.

[0071] Further embodiments are directed to methods of purifying water using the chlorine and chloramine destruction adsorbent products described above. The contacting step can be carried out by any means including, for example, flowing water over or through a bed of an adsorbent material product that destroys chlorine and chloramine, or a mixture of activated carbon that destroys chlorine and chloramine and an adsorbent material product that does not destroy chlorine and chloramine; introducing water into a filtration device that includes chlorine and chlorine-destroyed activated carbon or a mixture of chlorine and chlorine-destroyed activated carbon and an adsorbent material product that does not destroy chlorine and chloramine; introducing an adsorbent material product having a chlorine and chlorine-destroyed adsorbent material or a mixture of a chlorine and chlorine-destroyed adsorbent material product and an adsorbent material product that does not destroy chlorine and chloramine into a container for holding water. In some embodiments, the method includes additional steps. For example, in some embodiments, the method of purifying water includes filtering the water using, for example, a screen or sand filter, before, after, or both before and after contacting an adsorbent material product that destroys chlorine and chloramine or a mixture of an adsorbent material product that destroys chlorine and chloramine and an adsorbent material product that does not destroy chlorine and chloramine to remove particulates. Further embodiments include disinfecting the water to remove biological contaminants such as bacteria or other microorganisms, and in some embodiments, the method can include introducing a disinfectant into the water. In yet another embodiment, the method can include purifying the water, adjusting the pH of the water, etc., and combinations thereof.

[0072] The performance of the absorbent material product of the present invention is measured in various ways, including the "chloramine destruction number" (CDN) or "chlorine destruction number" (CI-DN) quantified in the following experimental section. These values quantify the amount of chloramine and / or chlorine that can be removed from water by the absorbent of the present invention. For CDN or the chloramine destruction number, the present invention contemplates a range of values including 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 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, 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 25.0, 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, or at least two of these values as endpoints. Alternatively, the CDN can be 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 55.0, at least about 60.0, at least about 65.0, at least about 70.0, at least about 75.0, at least about 80.0, with these numerical values as the lower limit of performance. In some embodiments, the chloramine destruction number is measured with respect to monochloramine.

[0073] The performance based on the chlorine destruction number (Cl-DN) can be in a range composed of about 70.0, about 75.0, about 80.0, about 85.0, about 90.0, about 95.0, about 100.0, about 110.0, about 120.0, about 120.0, about 140.0, about 150.0, about 160.0, about 170.0, about 180.0, about 190.0, about 200.0, about 210.0, about 220.0, about 230.0, about 240.0, about 250.0, or at least two of these values as endpoints. The performance according to the chlorine destruction number can also be at least about 70.0, at least about 75.0, at least about 80.0, at least about 85.0, at least about 90.0, at least about 95.0, at least about 100.0, at least about 150.0, at least about 200.0, or at least about 250.0, or any combination of those ranges. The chlorine destruction number can be from about 80.0 to about 150.0, or from about 120.0 to about 200.0, or from about 170.0 to about 250.0.

[0074] The measurable factor of the performance of the adsorbent of the present invention is considered to be the amount of "edge" nitrogen, which is different from "central" nitrogen in that the "edge" nitrogen atoms are part of pyrrole or pyridine groups present at the edges of the graphite sheet or plane. These nitrogen atoms are the most unstable and interact with various compounds that the adsorbent comes into contact with, such as chloramine and chlorine atoms. The amount of edge nitrogen can be determined by surface analysis techniques such as X-ray photoelectron spectroscopy (XPS). The amount of edge nitrogen measured by XPS or other surface analysis techniques can be from about 0.1 atomic % to about 2.0 atomic %, from about 0.2 atomic % to about 1.7 atomic %, from about 0.2 atomic % to about 1.5 atomic %, or from about 0.2 atomic % to about 1.2 atomic %, from about 0.2 atomic % to about 1.0 atomic %, from about 0.2 atomic % to about 0.8 atomic %, from about 0.2 atomic % to about 0.6 atomic %, from about 0.2 atomic % to about 0.4 atomic %, or any combination of the above ranges. Also, the amount of edge nitrogen measured again by XPS or other surface analysis techniques can be about 0.1 atomic %, about 0.2 atomic %, about 0.3 atomic %, about 0.4 atomic %, about 0.5 atomic %, about 0.6 atomic %, about 0.7 atomic %, about 0.8 atomic %, about 0.9 atomic %, about 1.0 atomic %, about 1.1 atomic %, about 1.2 atomic %, about 1.3 atomic %, about 1.4 atomic %, about 1.5 atomic %, about 1.6 atomic %, about 1.7 atomic %, about 1.8 atomic %, about 1.9 atomic %, about 2.0 atomic %, or any range formed by a combination of two of these values as the endpoints of the range.

[0075] Examples The present invention has been described in considerable detail with reference to its specific preferred embodiments, but other versions are possible. Therefore, the spirit and scope of the appended claims should not be limited to the descriptions and preferred versions contained herein. Various aspects of the present invention are described with reference to the following non-limiting examples.

[0076] Example 1 Activated carbon samples were tested for the removal of chlorine and chloramines. Chloramines refer to monochloramine, dichloramine, and trichloramine. When ammonia is in equilibrium with chlorine in solution, the form of chloramine depends on the pH. A chloramine solution with 1.5 g of ammonium chloride, 12.5 mL of 5% sodium hypochlorite, and deionized water was mixed to obtain a 1 L solution of 300 ppm chloramine at pH 9.0. At a pH value of 9.0, the chloramine species present at equilibrium is the monochloramine form, which is the most difficult to destroy. During the evaluation, 1.25 g of sodium carbonate was used to buffer the solution to maintain the pH of the solution. The chlorine solution consisted of 12.5 mL of 5% sodium hypochlorite and deionized water to obtain a 1 L solution of 300 ppm chlorine. 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 analysis, a fixed volume of 2.0 mL of activated carbon (size 80×325 mesh) was added to the stirred 1 L chloramine or chlorine solution. The volume of carbon used was determined from the apparent density of the 80×325 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 aliquots and analyzing for total chlorine using the standard HACH colorimetric EPA-approved Method 10070. The concentration of chloramine was measured using NSF / ANSI-42 (2015).

[0077] After the activated carbon was experimentally analyzed, the concentration-versus-time data for each activated carbon sample was plotted. The results are shown in Figure 1. Subsequently, the results were replotted as the natural logarithm of the total chlorine concentration and time to linearize the data according to the first-order reaction kinetics theory. The replotted results are shown in Figure 2. Next, a linear fit was applied to the data and the slope of the linear fit was determined. Since the initial concentration of total chlorine decreased over a period of 150 minutes, the slope was always negative. As a result, the value obtained by multiplying the absolute value of the slope by 1000 was used to quantify the rate of chloramine and chlorine decomposition (removal). The greater the absolute slope, the more effective the activated carbon is in removing chlorine and chloramine. In these experiments, the slope obtained from the linear fit of the first-order kinetic experimental data multiplied by 1000 is called the "chloramine destruction number" or CDN. For chlorine decomposition, the same was done for the experimental results of chlorine concentration, and the value was called the "chlorine destruction number" of Cl-DN.

[0078] In addition to chloramine, this embodiment is also effective in removing chlorine from the aqueous stream. Although the ability of the calcined activated carbon to remove chlorine was evaluated as described above, since the test solution was prepared without adding ammonium chloride, the solution contained 300 ppm of chlorine. The activated carbon particle size for chlorine analysis was 95%-325 mesh, corresponding to 95% of the activated carbon particles passing through 325 mesh. This corresponds to an opening size of 44 μm. However, the analysis of the chlorine concentration-versus-time data and its first-order rate slope is the same. The slope of the linear fit of this data is called the "chlorine destruction number" or Cl-DN.

[0079] Example 2 Two types of coal-based activated carbons were used as adsorbent intermediate materials. FILTRASORB 400 (F400) is a bituminous coal-based activated carbon with an iodine number of 1000 (minimum), a maximum moisture of 2 wt%, an effective size of 0.55 mm to 0.75 mm, a maximum uniformity coefficient of 1.9, a minimum attrition number of 75, and a weight ratio screen size in the US Sieve series of up to 5 wt% at 12 mesh (opening 1700 μm) and up to 4 wt% at 40 mesh (opening 425 μm). F400 activated carbon is available from Calgon Carbon Corp., Pittsburgh, PA. CENTAUR is a coal-based activated carbon prepared according to U.S. Patent No. 6,342,129 and is available from Calgon Carbon Corp., Pittsburgh, PA. The identified samples in Table 1 were oxidized in air at 500 °C for 1 hour in a tubular furnace. After cooling the samples, the samples confirmed to have urea added were impregnated with a 50% aqueous urea solution at a ratio of 4 mL of urea solution to 10 mL of urea. Calcination was carried out in a tubular furnace at 950 °C for 1 hour in nitrogen and then cooled with nitrogen. Activation was carried out in a tubular furnace at 950 °C for 15 minutes in a steam environment. Preliminary oxidation of the activated carbon increases the final nitrogen content of the activated carbon. This is shown in Table 1. When measured by elemental analysis (Galbraith Labs), the pre-oxidized samples contained more nitrogen (total nitrogen, wt%) than the non-oxidized samples. All samples were treated with the same amount of urea precursor. Furthermore, the pre-oxidized samples were more effective in destroying chloramine due to their high CDN values.

Table 1

[0080] In the prior art, the presence of activation gas or oxidation gas at high temperatures has the adverse effect of reducing the product yield and potentially reducing the nitrogen content of the final product due to the attack of the carbon structure by oxygen at high temperatures. Table 1 shows the effectiveness and advantages of the calcination process as the CDN values of all calcined samples are higher than those of the activated samples. This is true for both non-oxidized activated carbon and pre-oxidized activated carbon, but the highest CDN value was obtained when the activated carbon was pre-oxidized. Figure 3 shows the relationship between total nitrogen and the CDN value in a graph.

[0081] Example 3 The type of nitrogen incorporated into the activated carbon was characterized using X-ray photoelectron spectroscopy (XPS). This method was applied to the activated carbon samples shown in Table 1. The type of nitrogen present in the activated carbon is characterized as either "edge" nitrogen or "central" nitrogen. In "edge" nitrogen, the nitrogen atom is part of a pyrrole or pyridine group at the edge or end of a graphite sheet or plane, and "edge" nitrogen is identified by having a binding energy of -399 eV during XPS analysis.

[0082] In "central" nitrogen, the nitrogen atom is bonded as part of the internal structure of several condensed aromatic rings. Central nitrogen has a characteristic binding energy of -401 eV when analyzed using XPS. In the disclosed embodiments, when examining the type of nitrogen present in the urea-treated F400 or CENTAUR activated carbon in Table 1, when the sample is calcined for steam activation, the percentage of "edge" type nitrogen increases significantly. This trend is emphasized in Table 2.

Table 2

[0083] In all embodiments, the calcined activated carbon shows an increased percentage of edge form nitrogen relative to the central form when compared to steam-activated activated carbon. All calcined samples also have higher CDN values than the steam-activated samples. In some cases, the CDN value can be almost doubled for the calcined samples compared to the steam-activated only samples. It is a novel and unexpected discovery of the present invention that calcining the activated carbon to inertness produces a greater fraction of edge nitrogen and that these samples exhibit a faster chloramine removal rate than the steam-activated (and thus gasified) counterparts.

[0084] Figure 4 shows the influence of various forms of nitrogen on CDN. The amount of nitrogen for each instance was determined by XPS. As the total atomic nitrogen increased, the CDN value also increased. Notably, the increase in total atomic nitrogen by XPS is due mainly to an increase in edge nitrogen rather than central nitrogen. Edge nitrogen is the most chemically unstable nitrogen during the gasification or activation process. However, during calcination, edge nitrogen tends to remain with the carbon structure.

[0085] Without wishing to be bound by theory, the results appear to show that the proposed nitrogen treatment results in an increase in edge nitrogen and that most of the increase in total or bulk nitrogen, including central and edge nitrogen, is a result of this addition of edge nitrogen. This is important because edge nitrogen affects the surface interaction of the adsorbent and thus the performance of the adsorbent.

[0086] Example 4 Table 3 shows the effect of the addition of water or steam to the air atmosphere used for oxidation. To test this effect, first, F400 carbon was oxidized in air at 500 °C for 1 hour in a tubular furnace without adding water, then impregnated with a urea solution, and calcined as in Example 2 above. The results of this test are shown in Table 3 as the "dry air" sample.

[0087] Next, F400 carbon was provided together with humidified air saturated with water vapor at 25°C. Next, the F400 carbon and the humidified air were heated in a tubular furnace to 500°C for 1 hour, followed by impregnation with a urea solution and calcined as shown in Example 2 above. The results of this test are shown in Table 3 as the "humidified air" sample. Table 3 shows that when water is used in combination with a primary oxidant (in this case air), the CDN of carbon is significantly improved.

Table 3

[0088] Example 5 Table 4 provides the effects of different nitrogen-containing precursors and their ability to impart catalytic activity to activated carbon. For these tests, all nitrogen-containing precursors were added to F400 carbon at a ratio of 1 mole of nitrogen to 10 moles of carbon from the activated carbon. For the purpose of calculating the molar amount of nitrogen added via the nitrogen-containing precursor in this experiment, it was assumed that the activated carbon was composed entirely, or 100%, of carbon atoms.

[0089] The nitrogen-containing precursors identified as "dry" in Table 4 were added as a dry mixture to the oxidized activated carbon due to the lack of water solubility. Those described as "gas" were used in the form of a gas after air oxidation of the activated carbon. From the experimental data shown in Table 4, only the nitrogen-containing precursors containing reduced nitrogen in the -3 oxidation state significantly increased the CDN value compared to the CDN values of other oxidation states.

[0090] It is also contemplated that the nitrogen source can be added to the adsorbent raw material or the adsorbent intermediate itself, or into them. In one experiment, polyacrylonitrile was provided as a nitrogen precursor having activated carbon as an adsorbent intermediate. Next, polyacrylonitrile and activated carbon were mixed as a dry mixture. The CDN of the resulting adsorbent product was 4.6. Without wishing to be bound by theory, it is believed that upon thermal decomposition of the polyacrylonitrile polymer, nitrogen compounds react with the carbon skeleton and affect the destruction of chloramine and similar compounds.

Table 4

[0091] Example 6 The pre-oxidized and calcined activated carbon was also evaluated for chlorine destruction characterized by the Cl-DN value. Table 5 shows the performance as a CENTAUR adsorbent product or adsorbent intermediate. Each CI-DN test was prepared as provided in Example 2 above. [Table 5]

[0092] In Table 5, the CI-DN of the steam-activated CENTAUR adsorbent intermediate material was 72.8. Even when the CENTAUR adsorbent intermediate material was pre-oxidized and calcined without adding a urea nitrogen-containing precursor, the Cl-DN still improved to approximately 84.6. However, as in the case of chloramine, when the CENTAUR activated carbon was used as an adsorbent intermediate material, pre-oxidized first, mixed with urea, and finally calcined, the Cl-DN increased dramatically to 145.9. This significant increase in the C1-DN value indicates that the activated carbon is very effective in removing chlorine when it is pre-oxidized, mixed with a nitrogen source in the -3 oxidation state, and calcined.

[0093] Example 7 The oxidation of carbon was carried out using the oxidizing agents discussed above. 50 g of F400 activated carbon was contacted with 150 mL of the oxidizing agent shown in Table 1 below. The concentration of the oxidizing agent ranged from 1 to 32% in water and was stirred for 24 to 72 hours while in contact with the carbon. The mixture was filtered and dried at 150 °C for 3 hours, and then impregnated with a 50% urea solution in water at a ratio of 10 g of carbon to 4 mL of the 50% urea solution. Next, the impregnated carbon was calcined in nitrogen at 950 °C for 1 hour. The results were measured for their chloramine destruction numbers and are listed in Table 6 below. [Table 6]

[0094] From these results, it has been shown that peracetic acid treatment yields excellent results with a CDN of 54.2. Other oxidizing agents such as potassium persulfate, potassium peroxymonosulfate, and peracetic acid also gave good results as oxidizing agents, following or in combination with the treatment with urea. Any other reduced nitrogen precursor, particularly nitrogen compounds in the -3 oxidation state, combined with the disclosed oxidizing agents, is expected to be suitable for the production of these high CDN values or the high C1-DN values described above.

[0095] Example 8 Additional tests were carried out using the CENTAUR activated carbon described in the previous example. 15 g of CENTAUR activated carbon was contacted with 150 mL of peracetic acid at a concentration up to 20.5% in water and stirred for up to 120 hours. The mixture was filtered and then the carbon was dried at 80 °C for up to 12 hours. After drying, the carbon was impregnated with a 50% urea solution in water at a ratio of 10 g of carbon to 4 mL of urea solution. The impregnated carbon was then calcined in nitrogen at 950 °C for 1 hour. The chloramine destruction number of the resulting carbon was measured and the results are shown in Table 7 below.

Table 7

[0096] From these results, it has been demonstrated that peracetic acid oxidation treatment results in a significant improvement in chloramine destruction with a CDN value of 24.9. This is compared to the pre-oxidized, similarly impregnated CENTAUR activated carbon with a CDN of only 11.9. Furthermore, air-oxidized and urea-impregnated CENTAUR achieved a CDN value of 21.8.

Claims

1. 1. A method for producing an adsorbent material product, the method comprising: providing a sorbent material feedstock, the sorbent material feedstock comprising at least one of activated carbon, reactivated carbon, activated coke, or combinations thereof; oxidizing the sorbent material feedstock with an oxidizing agent selected from the group consisting of nitric acid, potassium peroxymonosulfate, potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, peracetic acid, acetic acid, calcium hypochlorite, sodium hypochlorite, hypochlorous acid, benzoyl peroxide, sodium percarbonate, sodium perborate, organic peroxides, organic hydroperoxides, peroxide based bleaches, chlorine based bleaches, mixtures of hydrogen peroxide and urea, mixtures of peracetic acid and urea, and combinations thereof; contacting the oxidized sorbent material feedstock with a nitrogen-containing precursor, the nitrogen-containing precursor being a reduced nitrogen compound; heating the oxidized sorbent material feedstock and the nitrogen-containing precursor to a temperature of about 850° C. to about 1050° C. under an inert atmosphere to form the sorbent material product; having the sorbent material product having a nitrogen edge concentration of at least about 0.20 atomic percent and a chloramine destruction number (CDN) of at least about 2.0; the nitrogen edge concentration is measured by X-ray photoelectron spectroscopy; and The CDN is calculated by measuring the total chloramine concentration using NSF / ANSI-42 (2015) in a standard sample contacted with the adsorbent for 150 minutes, plotting the total chloramine concentration versus time, replotting as the natural logarithm of the total chloramine concentration versus time and linearizing the data according to first order kinetics, applying a linear fit to the data, obtaining the slope of the linear fit of the natural logarithm of the total chloramine concentration versus time, and multiplying the absolute value of the slope by 1000. method.

2. 10. The method of claim 1, wherein the adsorbent material product has a CDN of at least about 5.

0.

3. The method of claim 1 , wherein the adsorbent material product has a CDN of about 10.0 to about 60.

0.

4. 10. The method of claim 1, wherein the sorbent material product has a Chlorine Destruction Number (C1-DN) of at least about 80.0; The C1-DN is calculated by measuring the total chlorine concentration in a standard sample contacted with the sorbent for 150 minutes using HACH colorimetric EPA approved method 10070, plotting the total chlorine concentration versus time, replotting as the natural logarithm of the total chlorine concentration versus time and linearizing the data according to first order kinetics, applying a linear fit to the data, obtaining the slope of the linear fit of the natural logarithm of the total chlorine concentration versus time, and multiplying the absolute value of the slope by 1000. method.

5. 5. The method of claim 4, wherein the C1-DN value is from about 80.0 to about 250.

0.

6. 10. The method of claim 1, wherein the adsorbent material product has a nitrogen edge concentration of about 0.20 atomic % to about 2.0 atomic %.

7. 2. The method of claim 1, wherein the nitrogen-containing precursor comprises reduced nitrogen in an oxidation state of -3.

8. 2. The method of claim 1, wherein the step of heating the oxidized sorbent material feedstock and nitrogen-containing precursor comprises heating to a temperature of about 950° C. to about 1050° C. under an inert atmosphere, thereby forming the sorbent material product.

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