Activated carbon recovery and regeneration method

Abstract

One aspect of the present invention relates to a method for recovering and regenerating activated carbon, comprising heating an activated carbon molded body in an inert atmosphere, and recovering activated carbon from the activated carbon molded body.

Description

Technical Field

[0001] This invention relates to methods for the recovery and regeneration of activated carbon. In particular, it relates to methods for recovering and regenerating activated carbon from activated carbon blocks used in water treatment that have adsorbed organic compounds and organochlorine compounds. Background Technology

[0002] Trace amounts of chlorinated trihalomethanes are present in purified water such as tap water and water used in food processing. Chlorinated trihalomethanes are suspected carcinogens, making their presence in purified water a cause for concern. Chlorinated trihalomethanes include chloroform, bromodichloromethane, and dibromochloromethane, with chloroform accounting for approximately 40-50% of the chlorinated trihalomethanes in purified water. Furthermore, these chlorinated trihalomethanes are known to be formed by the reaction of humic substances in the raw water with chlorine used for disinfection. In addition, although present in trace amounts, they also include unreacted humic substances and reaction derivatives formed from the reaction of humic substances with chlorine.

[0003] In addition, groundwater contains chlorinated halogenated vinyl compounds, such as trichloroethylene, believed to originate from semiconductor-related manufacturing and / or dry cleaning industries, at concentrations higher than those of chlorinated trihalomethanes in purified water. These substances are generally toxic, making their presence a cause for concern.

[0004] As described above, with the increasing awareness of health in recent years, water purifiers are being used to remove organic compounds, such as chlorinated trihalomethanes and chlorinated halogenated vinyl compounds, contained in purified water and groundwater. Among such water purifiers, purification devices including activated carbon molded bodies are known, that is, technologies that use activated carbon filters to treat activated carbon and remove these substances.

[0005] On the other hand, with the focus on sustainable development goals, there is a growing trend of recovering and regenerating powdered and / or granular activated carbon from activated carbon molded bodies in water purifiers and reusing activated carbon.

[0006] To date, methods for regenerating activated carbon have included heating under nitrogen to remove organochlorine compounds (see, for example, Patent Document 1). Additionally, methods for regenerating activated carbon in the presence of superheated steam have been proposed (see, for example, Patent Document 2).

[0007] However, the techniques described in the prior art are techniques for removing adsorbates adsorbed by activated carbon, not techniques for directly regenerating activated carbon using activated carbon molded bodies. Therefore, these techniques do not consider situations where elements other than the activated carbon constituting the activated carbon molded body (such as organic binders, water purifier casings, and other components) are decomposed through heat treatment to produce substances, which then adhere to the activated carbon through adhesion or other means, thereby affecting the activated carbon's adsorption capacity. Therefore, the aforementioned techniques cannot be considered sufficient regeneration methods.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Publication No. 2001-316106

[0011] Patent Document 2: Japanese Patent Publication No. 2011-572 Summary of the Invention

[0012] Therefore, the main objective of this invention is to provide a method for recovering and regenerating activated carbon from an activated carbon molded body that has been used in the treatment of water purification, groundwater, etc. This method does not require disassembling the activated carbon molded body for the regeneration process and can recover and regenerate activated carbon from the activated carbon molded body itself.

[0013] The inventors conducted dedicated research to solve the above-mentioned problems and discovered that the above-mentioned problems could be solved by a method having the following structure. Based on this insight, they conducted further and repeated research, thereby completing the present invention.

[0014] That is, one aspect of the present invention relates to a method for recovering and regenerating activated carbon, comprising: heating an activated carbon molded body under an inert atmosphere, and recovering activated carbon from the activated carbon molded body. Detailed Implementation

[0015] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments.

[0016] The activated carbon recovery and regeneration method of this embodiment includes: According to the method of this embodiment, the activated carbon can be directly regenerated without disassembling the used activated carbon molded body, which is simple and low cost to recover activated carbon, and can restore and regenerate the adsorption performance of activated carbon.

[0017] First, the activated carbon molded body used in this embodiment will be described.

[0018] The activated carbon molded body used in the recycling and regeneration method of this embodiment is a molded body formed using activated carbon and binder resin, etc.

[0019] The raw materials for the activated carbon used in the activated carbon molded body of this embodiment are not particularly limited. Examples include: plant-based carbon materials (such as wood, wood shavings, charcoal, fruit shells such as coconut shells and walnut shells, fruit seeds, by-products of pulp manufacturing, lignin, waste molasses, and other plant-derived materials); mineral-based carbon materials (such as peat, lignite, brown coal, bituminous coal, anthracite, coke, coal tar, coal pitch, petroleum distillation residues, petroleum pitch, and other mineral-derived materials); synthetic resin-based carbon materials (such as phenolic resin, polyvinylidene chloride, acrylic resin, and other synthetic resin-derived materials); and natural fiber-based carbon materials (such as natural fibers such as cellulose, regenerated fibers such as rayon, and other natural fiber-derived materials). These carbon materials can be used alone or in combination of two or more.

[0020] The activated carbon used in the activated carbon molded body of this embodiment is obtained by carbonizing and / or activating the carbonaceous material as described above. When carbonization is required, it is usually carried out in the absence of oxygen or air at a temperature of, for example, around 400–800°C, preferably 500–800°C, and more preferably around 550–750°C. As an activation method, either gas activation or chemical reagent activation can be used, or a combination of gas activation and chemical reagent activation can be used. In particular, when used for water purification, gas activation, which leaves less residue of impurities, is preferred. Gas activation can be carried out by reacting the carbonized carbonaceous material with an activation gas (e.g., water vapor, carbon dioxide gas, etc.) at a temperature of, for example, around 700–1100°C, preferably 800–980°C, and more preferably around 850–950°C. Considering safety and reactivity, it is preferable to use a water vapor gas containing 10–40% by volume of water vapor as the activation gas. There are no particular limitations on activation time and heating rate; they can be appropriately selected based on the type, shape, and size of the carbonaceous material chosen.

[0021] The activated carbon molded body of this embodiment is not particularly limited, and activated carbon as described above can be used, and it can be molded by either dry molding or wet molding. Furthermore, the molded body preferably contains a thermoplastic resin as a constituent component. On the other hand, molded bodies containing thermosetting resin are not preferred because the thermosetting resin may stick together or turn into carbides derived from the thermosetting resin during regeneration.

[0022] Examples of dry activated carbon molded bodies include those obtained by the following methods.

[0023] First, the activated carbon, binder resin (e.g., polyethylene, polypropylene, polyethylene terephthalate, etc.) and stabilizer (e.g., magnesium salts, calcium salts, etc. of oleic acid, stearic acid, etc.) are mixed as described above and introduced into a partially or completely confined space (e.g., a mold).

[0024] The mold is heated to approximately 140°C to approximately 300°C using a convection furnace, hydraulic press, or infrared heater to sinter the polymer particles. Heating time and temperature vary depending on the size (mass) of the mold and the shape of the molded product. For example, heating time is typically approximately 1 to approximately 100 minutes. The mold is then cooled, and the porous product is removed. Molding pressure is generally not required, but pressure may be applied as needed.

[0025] Furthermore, examples of wet activated carbon molded bodies include those obtained by the following methods.

[0026] First, the activated carbon and fibrous binder as described above are mixed. Next, the mixture obtained by mixing the activated carbon and binder resin is dispersed in water to prepare a slurry. A wet activated carbon molded body can be manufactured through the following steps: a filtration step, in which the slurry is drawn up and filtered to obtain a pre-molded body; a drying step, in which the pre-molded body is dried to obtain a molded body; and a step of grinding the outer surface of the molded body as needed.

[0027] There are no particular limitations on fibrous binders, as long as they can be fibrillated to wrap around carbonaceous materials and thus be shaped; both synthetic and natural products can be widely used. Examples of such fibrous binders include: acrylic fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, cellulose fibers, nylon fibers, aramid fibers, and pulp. The fiber length of the fibrous binder is preferably less than 4 mm.

[0028] Two or more fibrous binders can be used in combination. Polyacrylonitrile fibers or pulp are particularly preferred as binders. This can further increase the density and strength of the molded body and suppress performance degradation.

[0029] In a preferred embodiment, the water permeability of the fibrous binder, expressed as a CSF value, is approximately 10 to 150 mL. In this embodiment, the CSF value is determined according to the Canadian Standard Freeness Method, JIS P8121 "Test Method for Filterability of Pulp". Alternatively, the CSF value can be adjusted, for example, by fibrillating the fibrous binder. If the CSF value of the fibrous binder is less than 10 mL, water permeability is not achieved, potentially resulting in lower strength and higher pressure loss in the molded body. On the other hand, if the CSF value exceeds 150 mL, the powdered activated carbon cannot be adequately retained, leading to reduced strength and potentially poorer adsorption performance in the molded body.

[0030] Generally, the proportions in the wet activated carbon molded body are as follows: 100 parts by weight of activated carbon, preferably 3 to 10 parts by weight of fibrous binder, more preferably 4.5 to 6 parts by weight of fibrous binder. It should be noted that when the wet activated carbon molded body contains other functional components described later, the phrase "100 parts by weight of activated carbon" can be rewritten as "100 parts by weight of activated carbon and other functional components combined".

[0031] Provided that the effect of the present invention is not inhibited, the wet activated carbon molded body may also contain other functional components. Examples of other functional components include lead adsorbent materials such as titanosilicate or zeolite powders that can adsorb and remove soluble lead, ion exchange resins or chelating resins, or various adsorbent materials containing silver ions and / or silver compounds to impart antibacterial properties.

[0032] Activated carbon molded bodies are typically assembled into filters for use. In the recycling and regeneration method of this embodiment, the activated carbon molded bodies are subjected to heat treatment as described later. At this time, the activated carbon molded bodies can be removed from the used activated carbon filter and then heated, or they can be processed directly without disassembling the used activated carbon filter.

[0033] In this embodiment, the activated carbon filter is not particularly limited in its structure as long as it contains the activated carbon molded body obtained above. It can also be a cylindrical filter that includes a sealing element and a core in addition to the activated carbon molded body. As for the core that can be used in this embodiment, it is not particularly limited as long as it can be inserted into the hollow part of the cylindrical filter to enhance the cylindrical filter. Preferred examples include a triangular pipe, a netron pipe, or a ceramic filter. In addition, it can also be used by wrapping non-woven fabric or the like around the outer periphery of the core and / or the outer periphery of the activated carbon molded body.

[0034] In this embodiment, the seals, core, and non-woven fabric included in the activated carbon filter can be subjected to the heat treatment described later, along with the activated carbon molded body as described above. This eliminates the need to remove the activated carbon molded body from the filter for recycling and regeneration, which is very useful for industrial applications.

[0035] Furthermore, the activated carbon filter is often installed inside the housing and used as a filter element. This filter element is installed in the water purifier for water circulation, and the water circulation method can be either a full filtration method that filters the total amount of raw water or a circulating filtration method. In this embodiment, when the housing (casing) is made of organic material, the filter element formed by installing the activated carbon filter inside the housing can be directly subjected to the heat treatment described later. Furthermore, even if the filter element contains known non-woven fabric filters, various adsorbent materials, mineral additives, ceramic filter materials, etc., it can be directly heated.

[0036] To date, known methods for regenerating activated carbon require removing only the activated carbon from the filter or cartridge to remove adsorbents. Activated carbon filters contain not only activated carbon but also organic materials such as binder resins, core materials, and non-woven fabrics contained within the activated carbon substrate. Therefore, a complex process is needed to remove these organic materials, leaving only the activated carbon.

[0037] In contrast, in the method of this embodiment, activated carbon can be recovered and regenerated directly from the activated carbon filter and filter element without disassembling them.

[0038] In this embodiment, the activated carbon filter after a certain period of water flow, or the activated carbon molded body contained in the activated carbon filter, is used in the activated carbon recovery and regeneration process. The water flow conditions in the water purifier equipped with the activated carbon filter are not particularly limited, but to prevent excessive pressure loss, for example, for applications lasting 100–5000 hours... -1 The activated carbon filter in a water purifier undergoes a regeneration process, where water is passed through at a spatial velocity (SV) for a specified time. During this process, the activated carbon adsorbs free residual chlorine, trihalomethanes, other trace organic compounds, and organochlorine compounds from the raw water and permeate.

[0039] In this embodiment, activated carbon can be regenerated from an activated carbon molded body that has adsorbed at least one of the organic compound and the organochlorine compound. According to the method of this embodiment, activated carbon can be regenerated without direct contact with these organic and organochlorine compounds attached to the activated carbon, thus offering an advantage in terms of safety.

[0040] The recycling and regeneration method of this embodiment includes heating the activated carbon molded body under an inert atmosphere. This heat treatment can be carried out by directly placing the activated carbon molded body (or activated carbon filter or filter element) into a reactor and heating it (heat treatment).

[0041] The inert atmosphere used in this embodiment refers to an atmosphere that does not have any activity (oxidizing effect) within the heating treatment temperature range of this embodiment. Specifically, it is preferable to have an atmosphere formed by a gas with an oxygen content of 5% or less, more preferably 2% or less, and even more preferably 1% or less. By performing heating treatment under this inert atmosphere, activated carbon is less likely to react, and the reduction of activated carbon can be suppressed.

[0042] Inert gases such as nitrogen, argon, water vapor, combustion gases, carbon dioxide, and carbon monoxide can be used as the inert atmosphere. Among these, water vapor is preferred from the viewpoint of shortening recovery and regeneration time and improving the recovery rate during regeneration. The reasons for this are as follows, but are not limited to these.

[0043] Due to the high thermal conductivity of water vapor, the adsorbates on activated carbon, as well as organic matter other than activated carbon that constitutes the activated carbon molded body, activated carbon filter, and filter element, decompose rapidly. Therefore, these substances are induced to volatilize from the activated carbon surface before being adsorbed and fixed, decomposing without damaging the activated carbon surface. As a result, the time required for recovery and regeneration can be shortened, and activated carbon with a high regeneration recovery rate can be achieved.

[0044] The inert gas can be used alone or in mixtures of multiple gases. The proportions of the mixed gases are not particularly limited; for example, in the case of nitrogen and water vapor, the molar ratio of each is preferably in the range of 1:100 to 100:1, more preferably in the range of 2:98 to 99:1, and even more preferably in the range of 5:95 to 95:5. Furthermore, the inert atmosphere of this embodiment may contain trace amounts of gases other than the inert gas to a degree that does not cause oxidation.

[0045] The flow rate of the inert gas (gas) in the heat treatment depends on the amount of activated carbon molded body present in the reactor and is therefore not particularly limited. Preferably, in order to facilitate heat transfer to the activated carbon molded body and to more easily remove compounds generated by decomposition, the flow rate is typically adjusted in the range of 0.01 L / min to 10000 L / min, more preferably 0.1 L / min to 8000 L / min, and even more preferably in the range of 0.4 L / min to 4000 L / min.

[0046] In this embodiment, the heat treatment temperature for heating the activated carbon molded body is preferably 500°C to 1200°C. If the temperature is too low, the adsorbed substances may not be able to volatilize or decompose and volatilize, potentially leaving residues, which is therefore undesirable. Furthermore, if the temperature is too high, the pores of the regenerated activated carbon may become clogged due to heat, resulting in a decrease in adsorption capacity, which is also undesirable. Therefore, heating is typically performed at 500°C to 1200°C, preferably 520°C to 800°C, and more preferably 550°C to 800°C.

[0047] The heating time (heat treatment time) of the activated carbon molded body is not particularly limited and can be appropriately determined according to the size of the activated carbon molded body and the adsorption capacity of the adsorbent, but it is usually in the range of 1 minute to 300 minutes. If the heating time is too short, there is a risk that the adsorbent detachment may not be sufficient. On the other hand, if the heating time is too long, the pores of the regenerated activated carbon may be blocked due to heat, thereby reducing the adsorption capacity, which is not preferable. Therefore, the heating time is usually in the range of 1 minute to 300 minutes, preferably in the range of 5 minutes to 240 minutes, and more preferably in the range of 10 minutes to 220 minutes.

[0048] In this embodiment, the adsorbent material attached to the activated carbon, as well as the organic materials such as binders and non-woven fabrics used in the activated carbon molding and filter, are decomposed and volatilized through the heat treatment. During decomposition, a portion is oxidized into carbon dioxide, but the volatiles contain carbon monoxide, various organic compounds, hydrogen chloride, etc. These substances cannot be directly emitted into the atmosphere; therefore, as needed, they are rendered harmless through methods such as absorbing acidic substances with an alkaline scrubber, flame combustion decomposition, or catalytic combustion decomposition.

[0049] In this embodiment, the heating treatment method is not particularly limited and can be either intermittent or continuous. For intermittent heating, any type such as a box furnace or muffle furnace can be used. For continuous heating, any type such as a mesh belt furnace, roller kiln, or pusher furnace can be used, as long as the material can be conveyed in a shaped state.

[0050] The activated carbon molded body after heat treatment can be removed after cooling. The temperature at which it is removed is preferably a temperature that will not be oxidized by oxygen in the air. Therefore, it is preferable to cool the activated carbon molded body to below 300°C, more preferably below 200°C, in the reactor, and then expose it to air.

[0051] In this embodiment, the activated carbon regenerated by heat treatment is sometimes retained in the shape of the molded body even after heat treatment. However, as needed, it can also be re-crushed into powdered activated carbon, granular activated carbon, and / or fibrous activated carbon using a device such as a belt press for recycling and reuse.

[0052] The adsorption performance and other properties of the activated carbon regenerated by the recycling and regeneration method of this embodiment are restored and regenerated.

[0053] This specification discloses various techniques as described above, and its main techniques are summarized below.

[0054] That is, the activated carbon recovery and regeneration method involved in the first technical solution of the present invention includes: heating the activated carbon molded body under an inert atmosphere, and recovering activated carbon from the activated carbon molded body.

[0055] According to this method, activated carbon can be processed directly without disassembling the used activated carbon mold, thus simplifying and regenerating activated carbon at low cost.

[0056] The second technical solution of the present invention relates to a recycling and regeneration method in which the activated carbon molded body comprises a thermoplastic resin as a constituent component, in the recycling and regeneration method of the first technical solution. According to this method, it is possible to suppress resin adhesion or the formation of resin-derived carbides during regeneration.

[0057] The third technical solution of the present invention relates to a recycling and regeneration method in which, in the recycling and regeneration method of the first or second technical solution, the activated carbon molded body is a molded body used for adsorbing at least one of organic compounds and organochlorine compounds. According to this method, activated carbon can be regenerated without direct contact with the adsorbent attached to the activated carbon molded body, thus offering advantages in terms of safety.

[0058] The fourth technical solution of the present invention relates to a recycling and regeneration method in which, in the recycling and regeneration methods of any one of the first to third technical solutions, the temperature at which the activated carbon molded body is heated is 500°C to 1200°C. It is believed that, accordingly, the adsorbents of the activated carbon and organic binders other than the activated carbon constituting the activated carbon molded body can be effectively removed.

[0059] The fifth technical solution of the present invention relates to a recycling and regeneration method in which, in any one of the recycling and regeneration methods of the first to fourth technical solutions, the inert atmosphere is an atmosphere containing water vapor. It is believed that, accordingly, the adsorbents of activated carbon and organic binders other than activated carbon in the activated carbon molded body decompose rapidly, thus shortening the recycling and regeneration time and enabling the regeneration of activated carbon with a high recovery rate.

[0060] The recycling and regeneration method according to the sixth technical solution of the present invention, in the recycling and regeneration method of any one of the first to fifth technical solutions, involves heating the activated carbon molded body together with the activated carbon filter containing the activated carbon molded body.

[0061] The seventh technical solution of the present invention relates to a recycling and regeneration method in any of the recycling and regeneration methods of the first to sixth technical solutions, wherein the activated carbon molding is heated together with the filter element containing the activated carbon filter when the activated carbon molding is heated. Accordingly, it has the following advantages: activated carbon can be recycled and regenerated by directly processing the activated carbon filter or filter element without removing the activated carbon molding from the activated carbon filter or disassembling the filter element.

[0062] The recycling and regeneration method according to the eighth technical solution of the present invention, in the recycling and regeneration method of any one of the first to seventh technical solutions, involves recycling activated carbon selected from at least one of powdered activated carbon, granular activated carbon, and fibrous activated carbon. It is believed that, accordingly, the aforementioned effects can be obtained more reliably.

[0063] Example

[0064] The present invention will be further described in detail below through embodiments; however, the present invention is not limited to any of the embodiments.

[0065] <Example 1>

[0066] An activated carbon filter (KURAFILTER, a registered trademark) manufactured by Kuraray was used as a water purifier for tap water for approximately 12 months, resulting in a post-adsorption filter. This filter consisted of polyethylene (PE) seals, a PE inner tube (core), acrylic fiber adhesive, and polypropylene (PP) fiber nonwoven fabric; however, the seals, core, and nonwoven fabric were removed from the filter.

[0067] Then, samples were cut for determining the iodine and methylene blue (MB) adsorption amounts of the molded body, and the remaining molded body was placed in a box furnace connected to a superheated steam generator UPSSW-20H. The body was then heated in a steam atmosphere (2 kg / hr, 5 ppm oxygen content (0.0005%)) at a temperature of 500°C for a set time of 30 minutes. After 30 minutes, the body was cooled to 200°C, and the treated material was removed. The acrylic fiber binder had decomposed and volatilized, and only activated carbon was recovered. The obtained activated carbon was in powder and granular form.

[0068] Then, the iodine adsorption and methylene blue adsorption amounts of the samples obtained before heat treatment for determining the iodine adsorption and methylene blue adsorption amounts of the molded body were determined by the method described later.

[0069] In addition, the adsorption capacity of iodine and methylene blue was also measured on the activated carbon after heat treatment.

[0070] The results are summarized in Table 1.

[0071] <Example 2>

[0072] Except for the heat treatment performed without disassembling the seals, core, and nonwoven fabric from the activated carbon filter, the activated carbon was recovered and regenerated in the same manner as in Example 1. As a result, in the treated material after heat treatment, the seals, core, adhesive, and nonwoven fabric had decomposed and volatilized, and only the activated carbon was recovered. The obtained activated carbon was in powder and granular form.

[0073] In addition, in Example 2, the activated carbon filter before heat treatment was cut and a portion of it was taken out as a sample for measuring the amount of iodine adsorption and methylene blue adsorption.

[0074] Then, the iodine adsorption and methylene blue adsorption were measured on the samples before and after heat treatment, in the same manner as in Example 1. The results are shown in Table 1.

[0075] <Example 3>

[0076] Except for replacing the used filters with unused ones (that is, testing was conducted directly on unused activated carbon filters), the recycling and regeneration were performed in the same manner as in Example 2. As a result, in the heat-treated product, the seals, core, adhesive, and nonwoven fabric decomposed and volatilized, and only the activated carbon was recovered. The obtained activated carbon was in powder and granular form.

[0077] The acquisition of each sample and the determination of iodine adsorption and methylene blue adsorption were carried out in the same manner as in Example 2. The results are shown in Table 1.

[0078] <Example 4>

[0079] Except for changing the heating temperature to 700°C, the recycling and regeneration were performed in the same manner as in Example 2. As a result, in the heat-treated product, the seals, core, adhesive, and nonwoven fabric decomposed and volatilized, and only activated carbon was recovered. The obtained activated carbon was in powder and granular form.

[0080] The acquisition of each sample and the determination of iodine adsorption and methylene blue adsorption were carried out in the same manner as in Example 2. The results are shown in Table 1.

[0081] <Example 5>

[0082] In Example 2, a steam atmosphere was introduced with a steam rate of 1 kg / hr, an oxygen content of 5 ppm (0.0005%), and a nitrogen rate of 20 L / min, and the volume ratio of steam to nitrogen was set to 50:50. Otherwise, the experiment was conducted in the same manner as in Example 4. The acquisition of each sample and the determination of iodine adsorption and methylene blue adsorption were performed in the same way as in Example 2. The results are shown in Table 1.

[0083] <Example 6>

[0084] In Example 2, a water vapor atmosphere was introduced with a water vapor rate of 200 g / Hr, an oxygen content of 5 ppm (0.0005%), and a nitrogen rate of 36 L / min. The volume ratio of water vapor to nitrogen was set to 10:90. Otherwise, the experiment was conducted in the same manner as in Example 4. The acquisition of each sample and the determination of iodine adsorption and methylene blue adsorption were performed in the same way as in Example 2. The results are shown in Table 1.

[0085] <Comparative Example 1>

[0086] Except for heating in air at 500°C, the recovery and regeneration were performed in the same manner as in Example 2. As a result, the activated carbon burned along with other organic materials during the heat treatment, and no activated carbon was recovered. The iodine adsorption and methylene blue adsorption of the activated carbon molded sample before heat treatment were measured in the same manner as in Example 2. The results are shown in Table 1.

[0087] <Comparative Example 2>

[0088] Except for replacing the used activated carbon filter with an unused one, the recycling and regeneration were performed in the same manner as in Comparative Example 1. As a result, the activated carbon burned along with other organic materials during heat treatment, and no activated carbon was recovered. The iodine adsorption and methylene blue adsorption of the activated carbon molded sample before heat treatment were measured in the same manner as in Example 2. The results are shown in Table 1.

[0089] <Comparative Example 3>

[0090] In Example 2, a water vapor atmosphere was introduced with a water vapor flow rate of 1 kg / hr, an oxygen content of 5 ppm (0.0005%), a nitrogen flow rate of 18 L / min, and an oxygen flow rate of 2 L / min. Otherwise, the experiment was conducted in the same manner as in Example 4. The acquisition of each sample and the determination of iodine and methylene blue adsorption amounts were performed in the same way as in Example 2. The results are shown in Table 1.

[0091] <Evaluation Methods>

[0092] (Iodine adsorption capacity and methylene blue adsorption capacity)

[0093] The adsorption performance of activated carbon was evaluated based on its iodine and methylene blue adsorption capacities.

[0094] The central portion of the activated carbon molded body was cut off, and the nonwoven fabric and core were removed. In this state, it was dried at 115°C for 24 hours. Then, it was pulverized into particles smaller than 45 μm using a sample mill, and the iodine and methylene blue adsorption capacities of the activated carbon molded body were determined according to the method specified in JIS K 1474:2014 (Test Method for Activated Carbon). Using the activated carbon obtained after heating the activated carbon molded body in the Examples and Comparative Examples, the iodine and methylene blue adsorption capacities of the regenerated activated carbon were determined according to JIS K 1474.

[0095]

[0096] (Inspection)

[0097] As clearly shown in Table 1, the activated carbon recovered and regenerated by the method of the present invention regained its adsorption performance (adsorption capacity) compared to its state after use (before heat treatment). Furthermore, it was confirmed that the method of the present invention can recover activated carbon by treating the activated carbon molded body, including the binder. Moreover, according to the results of Examples 2-6, activated carbon can be recovered without removing the seals, core, non-woven fabric, etc., from the activated carbon filter. Furthermore, by comparing Example 3 with other examples, it was confirmed that the method of the present invention can restore and regenerate used activated carbon to a state close to that of unused activated carbon.

[0098] In contrast, in Comparative Examples 1 and 2, where air was used instead of an inert gas for heating treatment, the activated carbon burned in both used and unused filters, leaving no residue after treatment. Furthermore, the results of Comparative Example 3 confirmed that even when using steam and nitrogen, the surface of the activated carbon turned white and could not be regenerated when a gas containing oxygen was used.

[0099] This application is based on Japanese Patent Application No. 2023-36446, filed on March 9, 2023, the contents of which are incorporated herein by reference.

[0100] To illustrate the invention, the invention has been appropriately and sufficiently described above with reference to specific examples and other embodiments. However, it should be understood that modifications and / or improvements to the described embodiments can be readily made by those skilled in the art. Therefore, any modified or improved embodiments implemented by those skilled in the art that do not depart from the scope of protection of the claims set forth in the claims are to be interpreted as being included within the scope of protection of those claims.

[0101] Industrial availability

[0102] This invention has broad industrial applicability in the fields of activated carbon and water purification using activated carbon.

Claims

1. A method for recovering and regenerating activated carbon, characterized in that... include: The activated carbon molded body is heated under an inert atmosphere, and the activated carbon is recovered from the activated carbon molded body.

2. The method for recovering and regenerating activated carbon according to claim 1, characterized in that, The activated carbon molded body contains thermoplastic resin as a constituent component.

3. The method for recovering and regenerating activated carbon according to claim 1, characterized in that, The activated carbon molded body is a molded body used for adsorbing at least one of organic compounds and organochlorine compounds.

4. The method for recovering and regenerating activated carbon according to claim 1, characterized in that, The temperature for heating the activated carbon molded body is 500℃~1200℃.

5. The method for recovering and regenerating activated carbon according to claim 1, characterized in that, The inert atmosphere is an atmosphere containing water vapor.

6. The method for recovering and regenerating activated carbon according to claim 1, characterized in that, When the activated carbon molded body is heated, it is heated together with the activated carbon filter containing the activated carbon molded body.

7. The method for recovering and regenerating activated carbon according to claim 6, characterized in that, When the activated carbon molded body is heated, it is heated together with the filter element containing the activated carbon filter.

8. The method for recovering and regenerating activated carbon according to claim 1, characterized in that, The recycled activated carbon is selected from at least one of powdered activated carbon, granular activated carbon, and fibrous activated carbon.

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