Method for oxidizing chemical adsorbents and adsorbents produced thereby

Abstract

To provide sorbent material products that have enhanced performance in removing chloramine.SOLUTION: A sorbent material product has a nitrogen edge concentration of at least about 0.20 atom% and a chloramine destruction number (CDN) of at least about 2.0, and the nitrogen edge concentration is measured using x-ray photoelectron spectroscopy. The CDN is calculated by the steps of: determining the total concentration of chloramine using NFS / ANSI-42 (2015) in a standard sample that has been in contact with the sorbent over 150 minutes; plotting the total concentration of chloramine versus time; replotting the data as the natural logarithm of total chlorine concentration vs. time to linearize the data according to first order kinetic theory; applying a linear fit to the data; obtaining the slope of the linear fit of the natural logarithm of the total concentration of chloramine versus time; and multiplying the absolute value of the slope by 1000.SELECTED DRAWING: 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 nitrogen-containing precursors 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 temperatures 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 with respect to the material removed from the surface because various forms of oxygen (air, pure O2, dissociated oxygen from steam, dissociated oxygen from CO2, etc.) at high temperatures are strong carbon gasifying and oxidizing agents. As a result, much of the incorporated nitrogen that is involved in the catalytic activity and is part of the surface framework 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] An improved process for processing adsorbent materials is disclosed in U.S. Patent Application Publication No. 2018 / 0229217, filed on 13 February 2018, claiming priority to U.S. Provisional Application 62 / 458,371, filed on 13 February 2017. Both of these disclosures are incorporated herein by reference in their entirety.

[0004] Improvements to various processes for forming adsorbent materials are still needed. This invention provides these improvements through novel processes. In particular, this specification covers improved processes for the chemical oxidation of adsorbents. The following are prior art documents related to the invention of this application (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): (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 Specification (Patent Document 3) U.S. Patent Application Publication No. 2003 / 0209498 Specification (Patent Document 4) U.S. Patent Application Publication No. 2008 / 0073290 Specification (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 Specification (Patent Document 8) U.S. Patent Application Publication No. 2014 / 0013942 (Patent Document 9) U.S. Patent Application Publication No. 2016 / 0023920 Specification (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 Specification (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) Specification of Chinese Patent Application Publication No. 102553641 (Patent Document 26) Specification of Chinese Patent Application Publication No. 103626150 (Patent Document 27) German Patent No. 3620425 Specification (Patent Document 28) Japanese Patent Application Laid-Open No. 01-058331 (Patent Document 29) International Publication No. 2014164275 (Non-patent literature) (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 Literature 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; adding a nitrogen-containing precursor to the oxidized adsorbent material raw material, wherein the nitrogen-containing precursor is a reduced nitrogen compound; 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 breakdown number (CDN) of at least about 2.0, where CDN is the absolute value of the first-order linear kinetic fit multiplied by 1000 and applied to the natural logarithm of the chloramine concentration in water and the time it takes for the initial chloramine concentration to decrease over 150 minutes.

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

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

[0010] In another embodiment, the adsorbent material product has a chlorine depletion number (C1-DN) of at least about 80.0, where C1-DN is the absolute value of the first linear kinetic fit multiplied by 1000, and is applied to the natural logarithm of the chlorine concentration in water and the time it takes for the initial chlorine concentration to decrease over 150 minutes.

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

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

[0013] In another embodiment, the adsorbent material product has a nitrogen edge concentration of 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, the oxidized adsorbent material raw material and nitrogen-containing precursor are heated to a temperature of at least 700°C in an inert atmosphere, thereby forming the adsorbent material product.

[0017] In one embodiment, the adsorbent material product has a nitrogen edge concentration of at least about 0.20 atomic percent and a chloramine breakdown number (CDN) of at least about 2.0, where CDN is the absolute value of the first-order linear kinetic fit multiplied by 1000, and is applied to the natural logarithm of the chloramine concentration in water and the time it takes for the initial chloramine concentration to decrease over 150 minutes.

[0018] Another embodiment is an adsorbent material product formed by a method comprising the steps of: 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, mixtures of hydrogen peroxide and urea, mixtures of peracetic acid and urea, and combinations thereof; adding a nitrogen-containing precursor to the oxidized adsorbent material raw material, wherein the nitrogen-containing precursor is a reducing nitrogen compound; 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.

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

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

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

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

[0023] In another embodiment, the adsorbent material product has a nitrogen edge concentration of 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 includes an adsorbent material raw material which 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 nitrogen-containing precursor is to heat them to a temperature of at least 700°C in an inert atmosphere to form the adsorbent material product.

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

[0028] Another embodiment is an adsorbent material product formed by a method comprising the steps of: 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, mixtures of hydrogen peroxide and urea, mixtures of peracetic acid and urea, and combinations thereof; adding a nitrogen-containing precursor to the oxidized adsorbent material raw material, wherein the nitrogen-containing precursor is a reducing nitrogen compound; 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.

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

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

[0031] In another embodiment, the adsorbent material product is included in the filter device as a wet-molded shape formed from particles, solid monoliths, blocks, extruded shapes, molded shapes, pressed shapes, roll substrates or sheets, flat substrates or sheets, spunbond shapes, or fiber slurry, or is included in a plurality of the aforementioned structures.

[0032] In another embodiment, the oxidized adsorbent material raw material and nitrogen-containing precursor are heated 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 at least about 5.0 CDN.

[0034] One embodiment is a method for processing a liquid, the method comprising the step of contacting the liquid with an adsorbent material product having at least about 0.20 atomic% nitrogen edge concentration and at least about 2.0 chloramine breakdown number (CDN), where CDN is the absolute value of the first linear kinetic fit multiplied by 1000, and is applied to the chloramine concentration in water and the natural logarithm of the time it takes for the initial chloramine concentration to decrease over 150 minutes.

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

[0036] [Figure 1] Figure 1 shows the results of plotting the concentration versus time data for each activated carbon sample after experimental analysis of the activated carbon. [Figure 2] Figure 2 shows the above results replotted as the natural logarithm of total chlorine concentration against time. [Figure 3] Figure 3 shows the relationship between total nitrogen and CDN values ​​in a graph. [Figure 4] Figure 4 shows the effects of various forms of nitrogen on CDN. [Modes for carrying out the invention]

[0037] Before describing the compositions and methods of the present invention, it should be understood that these are subject to change, and the present invention is not limited to the specific methods, compositions, or methodologies described herein. Furthermore, the terms used herein are intended solely to describe specific versions or embodiments and are 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 those skilled in the art. Similar or equivalent methods and materials may be used in carrying out or testing embodiments of the present invention, but preferred methods, apparatus, and materials are described herein. All publications referenced herein are incorporated in their entirety by reference. Nothing herein should be construed as acknowledging that the present invention does not have prior rights to such disclosures by prior art.

[0038] It should also be noted that, as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include multiple references unless the context explicitly indicates otherwise. Thus, for example, a reference to “a combustion chamber” is a reference to “one or more combustion chambers,” and its equivalents known to those skilled in the art, and so on.

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

[0040] As used herein, the term “adsorbent” means any material exhibiting adsorption properties, absorption properties, or a combination of adsorption and absorption properties. Adsorption properties mean that atoms, ions, or molecules adhere to the surface of the adsorbent material. Absorption properties 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 treated 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. Adsorbent material raw material is not limited to and includes one or more adsorbent raw materials and adsorbent intermediate materials.

[0044] As used herein, the term “adsorbent material product” means any material that exhibits adsorbent properties after at least one processing step of an 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, this specification discloses compositions for removing chloramines, chlorine, peroxides, and other harmful compounds using adsorbents, as well as methods for producing such adsorbents. In other embodiments, the present invention discloses apparatus and equipment such as filters containing catalytic adsorbent materials. The apparatus and equipment include water filters and liquid filters. In other embodiments, the present invention covers methods for using these apparatus and equipment to remove harmful compounds such as chloramines, chlorine, and peroxides.

[0047] Embodiments include methods for producing adsorbent material products and adsorbents prepared by such methods. The method may include a step of oxidizing an adsorbent raw material. The step of oxidizing the adsorbent raw material can be carried out before adding a nitrogen-containing precursor. The oxidation step can be carried out by various techniques. In some embodiments, the oxidation step includes contacting the adsorbent raw material with an oxidizing agent. In some embodiments, the oxidizing agent includes 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 bleaches, chlorine-based bleaches, mixtures of hydrogen peroxide and urea, mixtures of peracetic acid and urea, and at least one of the above combinations.

[0048] In some embodiments, the oxidation step includes heating or otherwise treating the adsorbent material raw materials and the chemical oxidizing agent or oxidizing agent. In such embodiments, the heating step includes heating the adsorbent material raw materials and the oxidizing agent to a temperature in the range formed by 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 any combination of any two of the above values. In some embodiments, the heating step is carried out within any range where the above temperature values ​​are the lower limit of the range, i.e., heating is carried out 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 above ranges. In yet another embodiment, the oxidation step is a non-thermal process and is carried out without applying external heating to the mixture of oxidizing agent and / or adsorbent raw materials.

[0049] In some embodiments, multiple oxidation steps are performed on the adsorbent material supply material. The adsorbent material supply material comprises one or more adsorbent raw materials or adsorbent intermediate materials. The number of oxidation steps is not limited and may 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 indicated as the first oxidation step, the second oxidation step, the third oxidation step, the fourth oxidation step, and so on. The above steps of contacting the adsorbent raw material with an oxidizing agent are combined in some embodiments with steps of oxidizing the adsorbent raw material under specific atmospheric conditions described below.

[0050] An additional or multiple step of oxidizing the adsorbent material under a specific atmosphere includes one or more of a specific atmospheric temperature, a specific atmospheric composition, or a specific 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 about 150°C to about 1050°C. In some embodiments, the oxidation temperature is a range consisting of 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, about 750°C to about 850°C, about 850°C to about 950°C, about 950°C to about 1050°C, or any of these disclosed endpoints, or any combination of the above ranges or values ​​within those ranges.

[0051] In other embodiments, the oxidation process is carried out in an oxygen-containing environment including air, oxygen, vapor, ozone, oxygen plasma, nitrogen oxides, and hydrogen peroxide, carbon dioxide, inert gases, noble gases, or any combination of one or more of the above. The adsorbent material raw materials are in contact with or placed in the above oxygen-containing environment. The amount of oxygen is not limited. In some embodiments, the amount of oxygen is about 5% by volume, about 10% by volume, about 15% by volume, about 20% by volume, about 20.95% by volume (i.e., air), about 25% by volume, about 30% by volume, about 35% by volume, about 40% by volume, about 45% by volume, about 50% by volume, about 55% by volume, about 60% by volume, about 65% by volume, about 70% by volume, about 75% by volume, about 80% by volume, about 85% by volume, about 90% by volume, about 95% by volume, or about 100% by volume (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 approximately 0% to approximately 20%; approximately 0% to approximately 20.95%; approximately 20% to approximately 40%; approximately 40% to approximately 60%; approximately 60% to approximately 80%; or approximately 80% to approximately 100%.

[0052] In some embodiments, the oxygen-containing environment is dry and contains no moisture or substantially no measurable moisture. In other embodiments, the oxidizing environment for any of the above compounds can also be humidified. The level of humidification can be 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, oxidation is achieved by a non-thermal process. In such embodiments, the adsorbent is oxidized in the liquid or vapor phase at a temperature below about 100°C by contacting the adsorbent with an oxidizing acid such as hydrogen peroxide, ozone, chlorine, persulfates, percarbonates, nitric acid, or any combination thereof. Some adsorbents containing carbon oxidize slowly in the presence of air, with or without moisture, at room temperature; this oxidation is slow but is eventually sufficient to produce an oxidized adsorbent precursor. In some embodiments, the oxidation step is omitted, i.e., the adsorbent material raw material is not oxidized by a process faster than the slow oxidation that occurs naturally at room temperature under normal conditions.

[0054] The adsorbent material raw materials of the embodiments of this disclosure are not limited and are any materials known in the art. In some embodiments, the adsorbent material raw materials are adsorbent raw materials. The adsorbent raw materials are not limited and include carbonaceous materials, carbon black, bituminous coal, subbituminous coal, lignite, anthracite, peat, nut shells, pits, coconut shells, babassu nuts, macadamia nuts, dendezza 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 enumerated materials. In some embodiments, the adsorbent material raw materials are adsorbent intermediate materials. The adsorbent intermediate materials are not limited and include one or more 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 may 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 may be an unoxidized adsorbent intermediate product or adsorbent raw material.

[0055] In some embodiments, after oxidation is complete, the adsorbent intermediate is contacted with a reduced nitrogen-containing compound. As stated above, the term “reduced nitrogen” means any nitrogen-containing molecule or compound in which nitrogen has an oxidation state of -3. Reduced nitrogen-containing compounds include one or more of the following: 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 carried out in any manner. For example, the contacting step of the adsorbent intermediate can be achieved by dry mixing the adsorbent intermediate with the reducing nitrogen-containing compound, impregnating the adsorbent intermediate with a solution of the reducing nitrogen-containing compound, or contacting the adsorbent intermediate with a gaseous reducing nitrogen-containing compound.

[0056] In other embodiments, the nitrogen source may be the adsorbent material raw material itself, either 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 nitrogen-containing monomers and nitrogen-containing polymers. In some embodiments, the nitrogen-containing raw materials are monomers, oligomers, or polymers of acrylonitrile, polyacrylonitrile, urethane, polyurethane, amide, polyamide, nitrile rubber, and one or more combinations thereof. Where nitrogen-containing raw materials are selected, they may be combined with a disclosed step of adding a further nitrogen precursor, or they may be used alone without the additional step of adding a nitrogen precursor. 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 processed according to the present invention, instead of mixing with other untreated adsorbents.

[0057] In some embodiments, the adsorbent material raw material is calcined by heating to a temperature higher than about 400°C before, during, or both before and during exposure to the nitrogen-containing compound. In some embodiments, the adsorbent material raw material is calcined by heating to a temperature higher than about 700°C before, during, or both before and during exposure to the nitrogen-containing compound. In some embodiments, heating is performed after contacting the raw material with the nitrogen-containing compound. Calcination is generally performed by heating the adsorbent raw material or adsorbent intermediate product to a temperature sufficient to reduce the presence of surface oxides on the adsorbent raw material or adsorbent intermediate product. The temperature at which surface oxides are removed may be about 400°C to about 1050°C, about 400°C to about 1000°C, about 600°C to about 1050°C, about 800°C to about 1050°C, about 850°C to about 950°C, or any temperature range that incorporates the above endpoints or is within the above range. The heating and / or calcination temperature may be approximately 350°C, approximately 400°C, approximately 450°C, approximately 500°C, approximately 550°C, approximately 600°C, approximately 650°C, approximately 700°C, approximately 750°C, approximately 800°C, approximately 850°C, approximately 900°C, approximately 950°C, approximately 1000°C, approximately 1050°C, approximately 1100°C, approximately 1150°C, approximately 1200°C, or a range formed with any two of these values ​​as endpoints. The calcination process atmosphere may include inert nitrogen gas or noble gases such as helium, argon, neon, krypton, xenon, and radon. Heating and / or calcination can be carried out over a period of approximately 1 to approximately 120 minutes. After heating and / or calcination, the resulting adsorbent intermediate product or adsorbent material product may be cooled in an inert and / or noble gas atmosphere.

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

[0059] In some embodiments, adsorbent intermediates are treated to make them suitable for their intended use. Such additional treatment steps for adsorbent intermediates are not limited to and include, for example, grinding, dry mixing, impregnation, sorting, grading, screening, briquetting, or agglomeration of the adsorbent intermediates. Additional steps can be performed at any point in the process, and individual steps or specific steps can be repeated.

[0060] In some embodiments, the adsorbent material product has an average particle size (MPD) of about 4 mm or less, and in certain embodiments, the sorption material product has an MPD of 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 may vary depending on the embodiment, and the adsorbent may have a pore distribution including macropores (greater than 50 nm in diameter), mesopores (2 nm to 50 nm in diameter), and micropores (less than 2 nm in diameter).

[0061] Pore ​​size distribution can influence the types of materials that can be adsorbed by an adsorbent. In particular, for hydrocarbon molecules, the tendency of molecules to be adsorbed by activated carbon depends on pore size. Therefore, by selecting pore size and pore size distribution, it is possible to determine which chemical species will be adsorbed or not adsorbed by the adsorbent. A narrow pore size distribution can be used to adsorb only a small number of 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 relates to filter devices such as filters, filter cartridges, beds, and particulate or powdered carbon, which include the adsorbent material products described above. One or more of the above filter devices can be used in combination.

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

[0064] In some embodiments, adsorbent material products used in filter devices are provided in the form of solid monoliths, blocks, extruded shapes, molded shapes, pressed shapes, roll substrates or sheets, flat substrates or sheets, spunbond shapes, or wet-molded shapes formed from fiber slurries, or combinations 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 polymers, adhesives, carbonizable materials, and combinations thereof, which create 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 one or more combinations thereof. The filler is not limited and includes oxides, ceramics, clays, and minerals.

[0065] In some embodiments, the filter device includes additional components such as screens or other means for holding activated carbon within a compartment, or additional purification devices such as a filtration membrane. In some embodiments, the housing may include various components necessary to enable the filter to be incorporated 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, or various components necessary to ensure that water is delivered to a water pipe or faucet-mounted device or water distribution device, causing the water to pass through the filter before being discharged from the faucet. In particular, the filter device may include an inlet port for introducing water into the filter and an outlet port for distributing the filtered or treated water from the filter. In some embodiments, the filter device may include removable connecting means for connecting to a water source such as a sink pipe, hose, pipe fittings, faucet, or fountain at the inlet.

[0066] It should be noted that, when supplied in a filter device or in bulk, the adsorbent material products or adsorbent intermediates of this disclosure may be mixed with other adsorbent materials. Such mixing may occur during the manufacture of the adsorbent material itself or during the manufacture of the filter device. In some embodiments, the adsorbent material products or adsorbent intermediates of this disclosure are mixed in a manufacturing apparatus for producing a filter device, such as being mixed in an extruder or injection molding apparatus. In some embodiments, the adsorbent material products or adsorbent intermediates of this disclosure are blended with other sorbent materials provided to remove the same compounds (i.e., chloramines and chlorine) or other compounds. Other contaminants to be removed include nitrites, lead, mercury, arsenic, and organic compounds.

[0067] In some embodiments, the filter device may 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, placed inside 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 may also be made of any suitable metal such as aluminum, steel, stainless steel, titanium, magnesium, or combinations thereof. The filter housing may also be formed of any of the above polymers having metallized plastics, for example, electroplated or electroless plated or vapor-deposited aluminum, steel, stainless steel, titanium, magnesium, chromium, or combinations thereof. The filter housing and envelope may be spaced apart from each other, and in some embodiments, a particulate filter, such as filter paper, may be placed in the space to hold dust associated with the activated carbon. In certain embodiments, an additional adsorbent, such as carbon cloth, may be placed in the space. In some embodiments, the filter may include a perforated plate, a grooved grid, a mesh grill, a screen, or other means for securing the envelope inside the housing while allowing free flow of fluid through the housing.

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

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

[0070] Commercial or municipal water treatment systems may include larger filter devices or tanks designed to be attached to large, high-flow water pipes that provide beds positioned to receive water from natural sources during treatment. Such devices are well known in the art, and activated carbon-destroying chlorine and chloramines can be included in any such device. In some embodiments, beds or tanks containing granular activated carbon may 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, water may come into contact with an adsorbent material product at one or more locations in 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 systems, granular or powdered chlorine and chloramine-destroying adsorbent products can be used alone, or in mixtures of chlorine and chloramine-destroying adsorbent products and non-chlorine and chloramine-destroying adsorbent products. Treatment systems and equipment may include additional tanks and components such as, for example, balancing tanks, purifiers, biological treatment tanks or tanks, sand filters, membrane filters, etc., and combinations thereof. Alternatively, the treatment facility includes an adsorbent holding tank into which powdered activated carbon is added to the water being treated and then collected after adsorption.

[0071] Further embodiments relate to methods for purifying water using the chlorine and chloramine-destroying adsorbent products described above. The contact step can be carried out by any means, including, for example, flowing water over or through a bed of a chlorine and chloramine-destroying adsorbent material product, or a mixture of chlorine and chloramine-destroying activated carbon and a non-chlorine and chloramine-destroying adsorbent material product; introducing water into a filtration device containing chlorine and chlorine-destroying activated carbon or a mixture of chlorine and chlorine-destroying activated carbon and a non-chlorine and chlorine-destroying adsorbent material product; or introducing an adsorbent material product having a chlorine and chlorine-destroying adsorbent material or a mixture of chlorine and chlorine-destroying adsorbent material product and a non-chlorine and chlorine-destroying adsorbent material product into a container for holding water. In some embodiments, the method includes additional steps. For example, in some embodiments, a method for purifying water includes filtering the water using, for example, a screen or sand filter before, after, or both after, contact with an adsorbent material product that destroys chlorine and chloramines or a mixture of an adsorbent material product that destroys chlorine and chloramines and a non-chlorine and chloramine-destroying agent, in order to remove particulate matter. In further embodiments, the method includes disinfecting the water to remove biological contaminants such as bacteria or other microorganisms, and in some embodiments, the method may include introducing a disinfectant into the water. In yet another embodiment, the method may include steps of purifying the water, adjusting the pH of the water, and combinations thereof.

[0072] The performance of the sorbing material products of the present invention is measured by various methods, including the "chloramine destruction number" (CDN) or "chlorine destruction number" (CI-DN), which are quantified in the following experimental sections. These values ​​quantify the amount of chloramine and / or chlorine that can be removed from water by the adsorbent of the present invention. With respect to CDN or chloramine destruction numbers, the present invention relates to approximately 3.0, approximately 3.5, approximately 4.0, approximately 4.5, approximately 5.0, approximately 5.5, approximately 6.0, approximately 6.5, approximately 7.0, approximately 7.5, approximately 8.0, approximately 8.5, approximately 8.5, approximately 9.0, approximately 9.5, approximately 10.0, approximately 10.5, approximately 11.0, approximately 12.0, approximately 12.5, approximately 13.0, approximately 13.5, approximately 14.0, approximately 14.5, approximately 15.0, approximately 15.5, approximately 16.0, approximately 16.5, approximately 17.0, approximately 17.5, approximately 18.0, approximately 18.5, approximately 19.0, approximately 19.5. Intend to have values ​​in the range of approximately 20.0, 20.5, 21.0, 21.5, 22.0, 22.5, 23.0, 23.5, 24.0, 24.5, 25.0, 25.5, 26.0, 26.5, 27.5, 28.0, 28.5, 29.0, 29.5, 30.0, 35.0, 40.0, 45.0, 50.0, 55.0, 60.0, 65.0, 70.0, 75.0, 80.0, or an endpoint of at least two of these values. Alternatively, the CDN may have these values ​​as lower limits for performance, 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 55.0, at least about 60.0, at least about 65.0, at least about 70.0, at least about 75.0, and at least about 80.0. In some embodiments, the chloramine destruction number is measured with respect to monochloramine.

[0073] Performance based on the chlorine breakdown number (Cl-DN) may be in the range of approximately 70.0, 75.0, 80.0, 85.0, 90.0, 95.0, 100.0, 110.0, 120.0, 120.0, 140.0, 150.0, 160.0, 170.0, 180.0, 190.0, 200.0, 210.0, 220.0, 230.0, 240.0, 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 about 80.0 to about 150.0, or about 120.0 to about 200.0, or about 170.0 to about 250.0.

[0074] The measurable factor in the performance of the adsorbent of the present invention is considered to be the amount of “edge” nitrogen, which differs from “center” nitrogen in that “edge” nitrogen atoms are part of pyrrole or pyridine groups present at the edge 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 chloramines 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 may be about 0.1 atomic% to about 2.0 atomic%, about 0.2 atomic% to about 1.7 atomic%, about 0.2 atomic% to about 1.5 atomic%, or about 0.2 atomic% to about 1.2 atomic%, about 0.2 atomic% to about 1.0 atomic%, about 0.2 atomic% to about 0.8 atomic%, about 0.2 atomic% to about 0.6 atomic%, about 0.2 atomic% to about 0.4 atomic%, or any combination of the above ranges. Furthermore, the amount of edge nitrogen, again measured by XPS or other surface analysis techniques, may be approximately 0.1 atomic%, 0.2 atomic%, 0.3 atomic%, 0.4 atomic%, 0.5 atomic%, 0.6 atomic%, 0.7 atomic%, 0.8 atomic%, 0.9 atomic%, 1.0 atomic%, 1.1 atomic%, 1.2 atomic%, 1.3 atomic%, 1.4 atomic%, 1.5 atomic%, 1.6 atomic%, 1.7 atomic%, 1.8 atomic%, 1.9 atomic%, 2.0 atomic%, or any range formed by a combination of two of these values ​​as the endpoints of the range.

[0075] Examples While the present invention has been described in considerable detail with reference to certain preferred embodiments, other versions are also 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 embodiments.

[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 pH. A chloramine solution containing 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 of 9.0, the chloramine species present in equilibrium is the monochloramine form, which is the most difficult to break down. During evaluation, the solution was buffered with 1.25 g of sodium carbonate 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. Each 1 L solution of 300 ppm 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 (80 × 325 mesh size) was added to 1 L of stirred chloramine or chlorine solution. The volume of carbon used was determined from the apparent density of 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 the total chlorine using the standard HACH colorimetric EPA-approved method 10070. The chloramine concentration 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. The results were then replotted as the natural logarithm of total chlorine concentration versus time, and the data was linearized according to first-order kinetic theory. The replotted results are shown in Figure 2. Next, a linear fit was applied to the data, and the gradient of the linear fit was determined. The gradient was always negative because the initial total chlorine concentration decreased over a period of 150 minutes. As a result, the rate of chloramine and chlorine decomposition (removal) was quantified using the absolute value of the gradient multiplied by 1000. The larger the absolute gradient, the more effective the activated carbon is in removing chlorine and chloramine. In these experiments, the gradient obtained from the linear fit of the experimental data with a 1000-fold first-order kinetic theory is called the "chloramine decomposition number" or CDN. For chlorine decomposition, the same procedure is followed for the experimental results of chlorine concentration, and this value is called the "chlorine decomposition number" of Cl-DN.

[0078] In addition to chloramine, this embodiment is also effective in removing chlorine from aqueous streams. While the ability of calcined activated carbon to remove chlorine was evaluated as described above, the test solution was prepared without the addition of ammonium chloride, and therefore the solution contains 300 ppm of chlorine. The activated carbon particle size for the chlorine analysis was 95%-325 mesh, corresponding to 95% of the activated carbon particles passing through the 325 mesh. This corresponds to an opening of size 44 μm. However, the analysis of chlorine concentration and time data and their first-order velocity gradients is the same. The gradient of the linear fit of this data is called the "chlorine breakdown number" or Cl-DN.

[0079] Example 2 Two types of coal-based activated carbon were used as adsorbent intermediate materials. FILTRASORB 400 (F400) is a bituminous activated carbon with a minimum iodine count of 1000, maximum moisture content of 2 wt%, effective size of 0.55 mm to 0.75 mm, maximum uniformity coefficient of 1.9, minimum abrasion count of 75, and a weight-to-weight ratio screen size of up to 5 wt% at 12 mesh (opening 1700 μm) and up to 4 wt% at 40 mesh (opening 425 μm) in the US Sieve series. F400 activated carbon is available from Calgon Carbon Corp. in Pittsburgh, Pennsylvania. CENTAUR is a coal-based activated carbon prepared according to U.S. Patent No. 6,342,129 and is available from Calgon Carbon Corp. in Pittsburgh, Pennsylvania. The identified samples in Table 1 were oxidized in air at 500°C for 1 hour in a tubular furnace. After cooling the samples, samples confirmed to contain urea were impregnated with a 50% urea aqueous solution at a ratio of 4 mL of urea solution to 10 mL of urea. Calculation was performed in a tubular furnace at 950°C for 1 hour under nitrogen, followed by cooling under nitrogen. Activation was performed in a tubular furnace at 950°C for 15 minutes under steam. Pre-oxidation of the activated carbon increased the final nitrogen content of the activated carbon, as shown in Table 1. Elemental analysis (Galbraith Labs) showed that the pre-oxidized samples contained more nitrogen (total nitrogen, wt%) than the unoxidized samples. All samples were treated with the same amount of urea precursor. Furthermore, the pre-oxidized samples were more effective at destroying chloramines due to their higher CDN values. [Table 1]

[0080] In conventional techniques, the presence of an activating or oxidizing gas at high temperatures has adverse effects, such as reducing product yield and potentially lowering the nitrogen content of the final product due to oxygen attack on the carbon structure 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 was true for both non-oxidizing and pre-oxidizing activated carbon, but the highest CDN values ​​were obtained when the activated carbon was pre-oxidized. Figure 3 shows a graph of the relationship between total nitrogen and CDN value.

[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 “center” nitrogen. In “edge” nitrogen, the nitrogen atom is part of a pyrrole or pyridine group located at the edge or border of the 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. Analysis using XPS reveals that central nitrogen has a characteristic bond energy of -401 eV. In the disclosed embodiments, examining the types of nitrogen present in urea-treated F400 or CENTAUR activated carbon in Table 1, the percentage of "edge" type nitrogen increases significantly when the sample is calcined against steam activation. This trend is highlighted in Table 2. [Table 2]

[0083] In all embodiments, calcined activated carbon exhibits an increased percentage of edge nitrogen relative to central nitrogen compared to steam-activated activated carbon. All calcined samples also have higher CDN values ​​than steam-activated samples. In some cases, the CDN value of calcined samples can be nearly double that of steam-activated-only samples. A novel and unexpected finding of the present invention is that inert calcination of activated carbon generates a larger fraction of edge nitrogen, and these samples exhibit a superior and faster chloramine removal rate than their steam-activated (and therefore gasified) counterparts.

[0084] Figure 4 shows the effect of various forms of nitrogen on CDN. The amount of nitrogen in each instance was determined by XPS. As total atomic nitrogen increased, the CDN value also increased. Notably, the increase in total atomic nitrogen by XPS was mainly due 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] While we do not wish to be bound by theory, the results appear to indicate that the proposed nitrogen treatment results in an increase in edge nitrogen, and that the majority of the increase in total nitrogen 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 interactions of the adsorbent, and consequently, affects the performance of the adsorbent.

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

[0087] Next, F400 carbon was provided with humidified air saturated with water vapor at 25°C. The F400 carbon and humidified air were then heated in a tubular furnace to 500°C for 1 hour, followed by impregnation with urea solution and calcination 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 the CDN of carbon is significantly improved when water is used in combination with a primary oxidizer (in this case, air). [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 per 10 moles of carbon from the activated carbon. For the purpose of calculating the amount of nitrogen added via the nitrogen-containing precursors in this experiment, it was assumed that the activated carbon was composed entirely of carbon atoms, or 100% of carbon atoms.

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

[0090] The nitrogen source may also be added to the adsorbent raw material or adsorbent intermediate itself, or within them. In one experiment, polyacrylonitrile was provided as a nitrogen precursor with activated carbon as the adsorbent intermediate. The polyacrylonitrile and activated carbon were then mixed as a dry mixture. The resulting adsorbent product had a CDN of 4.6. While we do not wish to be bound by theory, it is thought that the thermal decomposition of the polyacrylonitrile polymer causes nitrogen compounds to react with the carbon skeleton, influencing the breakdown of chloramines and similar compounds. [Table 4]

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

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

[0093] Example 7 Carbon oxidation was carried out using the oxidizing agents considered 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 the mixture was stirred for 24 to 72 hours while in contact with the carbon. The mixture was filtered, dried at 150°C for 3 hours, and then impregnated with 50% urea solution in water at a ratio of 10 g of carbon to 4 mL of 50% urea solution. Next, the impregnated carbon was calcined in nitrogen at 950°C for 1 hour. The results were measured for the number of chloramines destroyed and are listed in Table 6 below. [Table 6]

[0094] These results demonstrate 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 yielded good results as oxidizing agents, either following or in combination with urea treatment. Any other reducing nitrogen precursors, particularly nitrogen compounds in the -3 oxidation state, in combination with the disclosed oxidizing agents are expected to be suitable for generating these high CDN values ​​or the high C1-DN values ​​mentioned above.

[0095] Example 8 Additional tests were conducted 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 of up to 20.5% in water and stirred for up to 120 hours. The mixture was filtered, and the carbon was then 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 obtained carbon was measured, and the results are shown in Table 7 below. [Table 7]

[0096] These results demonstrate that peracetic acid oxidation treatment results in a significant improvement in chloramine decomposition, with a CDN value of 24.9. This is compared to similarly impregnated, unpre-oxidized CENTAUR activated carbon, which has a CDN of only 11.9. Furthermore, air-oxidized and urea-impregnated CENTAUR achieved a CDN value of 21.8.

Claims

1. An adsorbent material product having at least about 0.20 atomic% nitrogen edge concentration, at least about 20.0 chloramine destructive number (CDN), and at least about 80.0 chlorine destructive number (Cl-DN), The aforementioned nitrogen edge concentration is measured by X-ray photoelectron spectroscopy. The CDN is calculated by the following steps: measuring the total concentration of chloramine in a standard sample that has been in contact with the adsorbent for 150 minutes using NSF / ANSI-42 (2015); plotting the total concentration of chloramine against time; re-plotting the total concentration of chloramine against time as the natural logarithm and linearizing the data according to first-order reaction kinetics; applying a linear fit to the data; obtaining the gradient of the linear fit of the natural logarithm of the total concentration of chloramine against time; and multiplying the absolute value of the gradient by 1000. The Cl-DN is calculated by the following steps: measuring the total chlorine concentration in a standard sample that has been in contact with the adsorbent for 150 minutes using the HACH colorimetric EPA-approved method 10070; plotting the total chlorine concentration against time; re-plotting the total chlorine concentration against time as a natural logarithm and linearizing the data according to first-order reaction kinetics; applying a linear fit to the data; obtaining the gradient of the linear fit of the natural logarithm of the total chlorine concentration against time; and multiplying the absolute value of the gradient by 1000. Adsorbent material products.

2. The adsorbent material product according to claim 1, wherein the adsorbent material product has a CDN of about 20.0 to about 60.

0.

3. An adsorbent material product according to claim 1, wherein the Cl-DN value is approximately 80.0 to approximately 250.

0.

4. An adsorbent material product according to claim 1, wherein the adsorbent material product has a nitrogen edge concentration of about 0.20 atomic% to about 2.0 atomic%.

5. The adsorbent material product according to claim 1, wherein the nitrogen-containing precursor contains reduced nitrogen in an oxidized state of -3.

6. A filter device having an adsorbent material product having at least about 0.20 atomic% nitrogen edge concentration, at least about 20.0 chloramine destruction number (CDN), and at least about 80.0 chlorine destruction number (Cl-DN), The aforementioned nitrogen edge concentration is measured by X-ray photoelectron spectroscopy. The CDN is calculated by the following steps: measuring the total concentration of chloramine in a standard sample that has been in contact with the adsorbent for 150 minutes using NSF / ANSI-42 (2015); plotting the total concentration of chloramine against time; re-plotting the total concentration of chloramine against time as the natural logarithm and linearizing the data according to first-order reaction kinetics; applying a linear fit to the data; obtaining the gradient of the linear fit of the natural logarithm of the total concentration of chloramine against time; and multiplying the absolute value of the gradient by 1000. The Cl-DN is calculated by the following steps: measuring the total chlorine concentration in a standard sample that has been in contact with the adsorbent for 150 minutes using the HACH colorimetric EPA-approved method 10070; plotting the total chlorine concentration against time; re-plotting the total chlorine concentration against time as a natural logarithm and linearizing the data according to first-order reaction kinetics; applying a linear fit to the data; obtaining the gradient of the linear fit of the natural logarithm of the total chlorine concentration against time; and multiplying the absolute value of the gradient by 1000. Filter device.

7. A filter device according to claim 6, wherein the filter device further comprises at least one binder or filler, or at least one or more additional adsorbent materials.

8. A filter device according to claim 6, wherein the adsorbent material product is included in the filter device as particles, solid monoliths, blocks, extruded shapes, molded shapes, pressed shapes, roll substrates or sheets, flat substrates or sheets, spunbond shapes, or wet-molded shapes formed from a fiber slurry, or is included in one of the aforementioned structures.

9. A filter device according to claim 6, wherein the adsorbent material product has a CDN of about 20.0 to about 60.

0.

10. A method for processing a liquid, the method comprising the step of contacting the liquid with an adsorbent material product having at least about 0.20 atomic% nitrogen edge concentration, at least about 20.0 chloramine destructive number (CDN), and at least about 80.0 chlorine destructive number (Cl-DN), The aforementioned nitrogen edge concentration is measured by X-ray photoelectron spectroscopy. The CDN is calculated by the following steps: measuring the total concentration of chloramine in a standard sample that has been in contact with the adsorbent for 150 minutes using NSF / ANSI-42 (2015); plotting the total concentration of chloramine against time; re-plotting the total concentration of chloramine against time as the natural logarithm and linearizing the data according to first-order reaction kinetics; applying a linear fit to the data; obtaining the gradient of the linear fit of the natural logarithm of the total concentration of chloramine against time; and multiplying the absolute value of the gradient by 1000. The Cl-DN is calculated by the following steps: measuring the total chlorine concentration in a standard sample that has been in contact with the adsorbent for 150 minutes using the HACH colorimetric EPA-approved method 10070; plotting the total chlorine concentration against time; re-plotting the total chlorine concentration against time as a natural logarithm and linearizing the data according to first-order reaction kinetics; applying a linear fit to the data; obtaining the gradient of the linear fit of the natural logarithm of the total chlorine concentration against time; and multiplying the absolute value of the gradient by 1000. method.

11. The method according to claim 10, wherein the adsorbent material product has about 20.0 to about 60.0 CDN.

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