Heavy metal adsorbent, water purification material and manufacturing method of heavy metal adsorbent

Abstract

The present invention provides a heavy metal adsorbent comprising zeolite, wherein the median particle size of the zeolite based on volume is 10.0 μm or more, and the pore volume measured in the pore volume calculation range of 10 nm to 1000 nm by mercury intrusion porosimetry is 0.1000 cm 3 / g or less.

Description

Technical Field

[0001] The present invention relates to a heavy metal adsorbent, a water purification material, and a method for manufacturing a heavy metal adsorbent. Background Art

[0002] Various granulated zeolites are disclosed in Patent Documents 1 to 3 (the entire disclosures of these documents are hereby incorporated by reference in their entirety).

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-190942

[0004] Patent Document 2: Japanese Patent Application Laid-Open No. 57-122932

[0005] Patent Document 3: WO2006 / 082898A1 Summary of the Invention

[0006] In recent years, there has been a demand to reduce heavy metals contained in tap water. For example, as a specific example of heavy metals contained in tap water, lead can be cited. The reason for the mixing of lead in tap water is considered to be that the water pipes installed in the first half of the 1900s were lead pipes.

[0007] As a method for removing heavy metals from tap water, a method of adsorbing heavy metals to a water purifier filter has been widely used. In this regard, the fact that zeolite can adsorb and remove heavy metal ions (such as lead ions) in water has long been known. Therefore, for the purpose of adsorbing and removing heavy metal ions contained in tap water, a water purifier filter in which zeolite is mixed with an activated carbon filter has been used in recent years. However, existing zeolites are too fine for use in water, so they flow out of the water purifier filter. In particular, since zeolite contains aluminum in its constituent elements, the outflow of fine zeolite into drinking water prepared by passing tap water through a water purifier filter causes aluminum elements to be mixed into the drinking water, which is not preferable.

[0008] An object of one aspect of the present invention is to provide a heavy metal adsorbent made of zeolite suitable for water purification use.

[0009] As described above, the use of particulate zeolite in water purification results in the mixing of aluminum into drinking water. Therefore, the particle size of zeolite, which is usually mixed in the activated carbon filter of a water purifier, is considered preferably 10 μm or more. For this reason, granulating zeolite to increase its particle size can be considered. As a method for granulating zeolite, a method of granulating zeolite using a binder (see Patent Document 1), a method of further zeolitizing the binder portion of granulated zeolite to obtain binder-free zeolite (see Patent Document 2), etc. have been proposed. In addition, a method of pseudo-granulating by attaching zeolite to the surface of activated carbon via a polymer has also been proposed (see Patent Document 3). However, the physical strength of the granulated zeolite obtained by the above methods is insufficient. Therefore, when manufacturing a filter by mixing activated carbon and these granulated zeolites, due to physical friction during the kneading process, the particles will collapse, and as a result, the micronized zeolite particles will flow out from the water purifier filter. In addition, even for a filter obtained by processing under conditions where physical friction is suppressed as much as possible, when in actual use and in contact with water, the granulated body will gradually collapse, resulting in the micronized zeolite particles flowing out from the water purifier filter. In this regard, the inventors considered that in the granulated zeolite obtained by the above methods, there are a large number of pores (such as mesopores and / or macropores) in the particles. Therefore, not only is the physical strength of the granulated body weak, but also when in contact with water, the strength will be further weakened due to the inflow of water molecules into the pores. In response to this, the inventors conducted in-depth research and as a result newly discovered a heavy metal adsorbent made of the following zeolite. The pore volume of the following zeolite is 0.1000 cm 3 / g or less. The inventors speculate that this, for example, helps the particles not to collapse easily during the friction in manufacturing the activated carbon filter and contact with water. However, it should be noted that the speculation described in this specification is not limited to the present invention.

[0010] One aspect of the present invention is as follows.

[0011] [1] A heavy metal adsorbent comprising zeolite, wherein the median particle size of the zeolite based on volume is 10.0 μm or more, and the pore volume measured for the pore volume calculation range of 10 nm to 1000 nm by mercury intrusion porosimetry is 0.1000 cm 3 / g or less.

[0012] [2] The heavy metal adsorbent according to [1], wherein the reduction rate of the median particle size of the zeolite after ultrasonic treatment at an output power of 40 W for 600 seconds is 20% or less.

[0013] [3] The heavy metal adsorbent according to [1] or [2], wherein the median particle size is 20.0 μm or more and 50.0 μm or less.

[0014] [4] The heavy metal adsorbent according to any one of [1] to [3], wherein the pore volume is 0.0200 cm 3 / g or less.

[0015] [5] The heavy metal adsorbent according to any one of [1] to [4], wherein the zeolite is selected from zeolite A, zeolite X, zeolite Y, and zeolite P.

[0016] [6] The heavy metal adsorbent according to any one of [1] to [5], wherein the zeolite is zeolite X.

[0017] [7] The heavy metal adsorbent according to any one of [1] to [6], wherein the heavy metal is one or more heavy metals selected from lead, copper, zinc, and cadmium.

[0018] [8] The heavy metal adsorbent according to [1], wherein the reduction rate of the median particle size of the zeolite after ultrasonic treatment at an output power of 40 W for 600 seconds is 20% or less,

[0019] the median particle size is 20.0 μm or more and 50.0 μm or less,

[0020] the pore volume is 0.0200 cm 3 / g or less,

[0021] the zeolite is zeolite X, and

[0022] the heavy metal is one or more heavy metals selected from lead, copper, zinc, and cadmium.

[0023] [9] A water purification material comprising the heavy metal adsorbent according to any one of [1] to [8].

[0024]

[10] The method for producing the heavy metal adsorbent according to any one of [1] to [8] above, the method comprising:

[0025] Adding a silicon compound X and an aluminum compound Y to a zeolite seed-containing slurry A at a temperature in the range of 60°C to 200°C simultaneously or in any order,

[0026] The addition of the above X satisfies the following (1), and the addition of the above Y satisfies the following (2).

[0027] (1) The total addition amount of X is such that the amount of silicon element in X based on mol is 3.5 times or more the amount of silicon element in the zeolite seed,

[0028] Based on the amount of silicon element in X per 1 mol of silicon element in the zeolite seed, the addition amount of X per hour is 5.00 mol or less.

[0029] (2) The total addition amount of Y is an amount such that the amount of aluminum element in Y on a molar basis is 3.5 times or more the amount of aluminum element in the zeolite seed crystal.

[0030] Based on the amount of aluminum element in Y per 1 mol of the aluminum element in the zeolite seed crystal, the addition amount of Y per hour is 5.00 mol or less.

[0031] According to one aspect of the present invention, a heavy metal adsorbent made of zeolite suitable for water purification use, and a water purification material containing the heavy metal adsorbent can be provided. Further, according to one aspect of the present invention, a method for manufacturing the above heavy metal adsorbent can be provided. Detailed Description of the Invention

[0032] [Heavy Metal Adsorbent]

[0033] One aspect of the present invention relates to a heavy metal adsorbent containing zeolite, the median particle size of the zeolite on a volume basis being 10.0 μm or more, and the pore volume measured for the pore volume calculation range of 10 nm to 1000 nm by mercury intrusion porosimetry being 0.1000 cm 3 / g or less.

[0034] Hereinafter, the above heavy metal adsorbent will be described in more detail.

[0035] <Zeolite>

[0036] The above heavy metal adsorbent contains zeolite having a median particle size and a pore volume within the above ranges. Zeolite can be a hydrous aluminosilicate containing an alkali metal or an alkaline earth metal in aluminosilicates, formed by a rigid anionic framework having regular channels (tubular pores) and cavities (voids). Zeolites can be classified into synthetic zeolites such as type A zeolite, type X zeolite, type Y zeolite, type P zeolite, type T zeolite, type L zeolite, β-type zeolite, ZSM-5; and natural zeolites such as mordenite, clinoptilolite, and chabazite. The zeolite constituting the above heavy metal adsorbent is preferably a synthetic zeolite, preferably a zeolite selected from type A zeolite, type X zeolite, type Y zeolite, and type P zeolite, more preferably a zeolite selected from type A zeolite, type X zeolite, and type P zeolite, and still more preferably type X zeolite.

[0037] (Median Particle Size)

[0038] The "median particle size" in the present invention and this specification is the median particle size based on volume. The "median particle size" is also referred to as "D50" and can be measured by the laser diffraction scattering particle size distribution measurement method. As a specific example of the measurement conditions, the following measurement conditions can be cited. The median particle size recorded in the Examples section described later is the value measured by the laser diffraction scattering particle size distribution measurement method under the following measurement conditions.

[0039] Measuring device: MT3300EXII manufactured by MicrotracBEL

[0040] Calculation mode: MT3000II

[0041] Standard: Volume standard

[0042] Transmittance: Transmission

[0043] Shape: Non-spherical

[0044] Solvent: Water

[0045] Particle refractive index: 1.39

[0046] Ultrasonic treatment: Output power 40W, time 120 seconds

[0047] Flow rate: 65%

[0048] From the viewpoint of suppressing the outflow of zeolite particles when applied to water purification, the median particle size of the above zeolite is 10.0 μm or more, preferably 15.0 μm or more, and more preferably 20.0 μm or more. In addition, from the viewpoint of the adsorption rate of heavy metals, the median particle size of the above zeolite is preferably 60.0 μm or less, more preferably 55.0 μm or less, and further preferably 50.0 μm or less.

[0049] (Pore volume)

[0050] The "pore volume" in the present invention and this specification is the pore volume measured by the mercury intrusion method for the pore volume calculation range of 10 nm to 1000 nm. As a specific example of the measurement conditions, the following measurement conditions can be cited. The pore volume recorded in the Examples section described later is the value measured by the mercury intrusion method under the following measurement conditions.

[0051] Measuring device: Pore Master 60-GT manufactured by Quanta Chrome

[0052] Sample amount: Approximately 0.3 - 0.4 g

[0053] Sample cell: Small cell (10φ × 30 mm)

[0054] Measurement range: 20 psia to 60000 psia (10 μm to 0.0036 μm)

[0055] Calculation range of pore volume: 10 to 1000 nm (0.01 μm to 1 μm)

[0056] The pore volume of the above zeolite is 0.1000 cm 3 / g or less. Zeolites with a pore volume of 0.1000 cm 3 / g or less are considered to have high physical strength and little reduction in strength due to contact with water. These properties can help reduce the outflow of zeolite particles from the water purifier filter as described above. From the above perspective, the pore volume of the above zeolite is preferably 0.0800 cm 3 / g or less, more preferably 0.0600 cm 3 / g or less, further preferably 0.0400 cm 3 / g or less, even more preferably 0.0200 cm 3 / g or less. The pore volume of the above zeolite can be, for example, 0.0010 cm 3 / g or more, 0.0020 cm 3 / g or more or 0.0030 cm 3 / g or more, but is not limited to the values exemplified here.

[0057] (Median particle size reduction rate)

[0058] For zeolites, from the perspective of reducing the outflow of fine particles of zeolites from the water purifier filter as described above, high physical strength is preferred. As an index of the physical strength of zeolites, the median particle size reduction rate obtained by the following method can be cited.

[0059] Except that only the ultrasonic treatment conditions are changed to the conditions described in Table 1 below, under the same conditions as the measurement conditions of the median particle size previously listed as a specific example, the median particle size A value under the condition of no ultrasonic treatment and the median particle size B value after 5 times of ultrasonic treatment are measured respectively. When measuring the A value, the output power of the ultrasonic wave is set to 0 W and the flow rate is set to 65% as described above. When measuring the B value, a total of 5 times of ultrasonic treatment are carried out under the ultrasonic treatment conditions shown in Table 1. Therefore, the total ultrasonic treatment time is 600 seconds. When measuring the B value, the flow rate is set to 65% as described above. According to the measured A value and B value, the median particle size reduction rate (unit: %) is calculated by the following calculation formula. The median particle size reduction rate obtained in this way is recorded as "the median particle size reduction rate after 600 seconds of ultrasonic treatment with an output power of 40 W", or simply recorded as "the median particle size reduction rate".

[0060] Median particle size reduction rate = [(A - B) / A] × 100

[0061] [Table 1]

[0062] Ultrasonic treatment conditions Median particle size [A] under no ultrasonic treatment conditions Output power OW (*), time 600 seconds Median particle size [B] after 5 times of ultrasonic treatment Output power 40W, time 120 seconds × 5

[0063] *) Ultrasonic treatment OFF

[0064] The above zeolite can exhibit a median particle size reduction rate of 20.0% or less. The fact that the above zeolite can exhibit a median particle size reduction rate of 20.0% or less can contribute to the above zeolite having a pore volume within the previously described range. The median particle size reduction rate of the above zeolite is preferably 18.0% or less, more preferably 16.0% or less, further preferably 14.0% or less, still further preferably 12.0% or less, and even further preferably 10.0% or less. Additionally, the median particle size reduction rate of the above zeolite can be, for example, 0%, 0% or more, greater than 0%, 0.1% or more, 0.5% or more, 1.0% or more, 2.0% or more, or 3.0% or more. The smaller the value of the median particle size reduction rate of the above zeolite, the better, and it is preferably 0%.

[0065] As the heavy metals that can be adsorbed by the above heavy metal adsorbent, metals with a specific gravity of 4 or more can be cited. For example, various heavy metals such as lead, copper, cadmium, zinc, nickel, and mercury can be listed. In one aspect, the above heavy metal adsorbent can be used as a lead adsorbent. For example, as previously described, since it is desired to reduce the lead contained in tap water, it is preferable that the above heavy metal adsorbent functions as a lead adsorbent. In one aspect, the above heavy metal adsorbent can function as a copper adsorbent, a zinc adsorbent, a cadmium adsorbent, etc. Additionally, in one aspect, the above heavy metal adsorbent can function as one or more selected from a lead adsorbent, a copper adsorbent, a zinc adsorbent, and a cadmium adsorbent, and can also function as 2, 3, or 4 of them. The above heavy metal adsorbent can be used, for example, as a component contained in the water purifier filter of a water purifier.

[0066] The above heavy metal adsorbent can be manufactured by the manufacturing method of the heavy metal adsorbent according to one aspect of the present invention described in detail below. Among them, the above heavy metal adsorbent only needs to contain zeolite with a median particle size based on volume of 10.0 μm or more and a pore volume measured within the pore volume calculation range of 10 nm to 1000 nm by mercury intrusion porosimetry of 0.1000 cm 3 / g or less, and is not limited to the heavy metal adsorbent manufactured by the above manufacturing method.

[0067] [Water purification material]

[0068] One aspect of the present invention relates to a water purification material containing the above heavy metal adsorbent. The water purification material may be composed only of the above heavy metal adsorbent, or may contain the heavy metal adsorbent and one or more other components. For example, as one aspect of the water purification material, a water purifier filter obtained by mixing the above heavy metal adsorbent with an activated carbon filter can be cited. Regarding the details of the above water purification material, publicly known techniques related to water purification materials containing zeolite can be applied.

[0069] [Method for manufacturing heavy metal adsorbent]

[0070] One aspect of the present invention relates to a method for manufacturing the above heavy metal adsorbent. The manufacturing method includes: adding a silicon-containing compound X and an aluminum-containing compound Y to a zeolite seed slurry A at a temperature in the range of 60°C to 200°C. Further, the addition of the above X satisfies the following (1), and the addition of the above Y satisfies the following (2).

[0071] (1) The total addition amount of X is such that, on a molar basis, the amount of silicon element in X is 3.5 times or more the amount of silicon element in the zeolite seed,

[0072] Based on the amount of silicon element in X relative to 1 mol of silicon element in the zeolite seed, the addition amount of X per hour is 5.00 mol or less.

[0073] (2) The total addition amount of Y is such that, on a molar basis, the amount of aluminum element in Y is 3.5 times or more the amount of aluminum element in the zeolite seed,

[0074] Based on the amount of aluminum element in Y relative to 1 mol of aluminum element in the zeolite seed, the addition amount of Y per hour is 5.00 mol or less.

[0075] Hereinafter, the above manufacturing method will be described in more detail.

[0076] <Slurry A>

[0077] Slurry A contains zeolite seeds. The zeolite seeds may be synthetic zeolites or natural zeolites, and may be one or more zeolites selected from synthetic zeolites and natural zeolites. Synthetic zeolites can be industrially manufactured and generally have high purity. Therefore, as the zeolite seeds, synthetic zeolites are preferred. From the viewpoint of suppressing the generation of by-products other than the target zeolite, it is preferred that the framework structure of the zeolite seeds is the same as that of the target zeolite to be manufactured. For example, in order to manufacture zeolite A, it is preferred to use zeolite A as the seed, and in order to manufacture zeolite X, it is preferred to use zeolite X as the seed. The slurry is a mixture of a liquid and a solid, and slurry A contains at least zeolite seeds as the solid. The liquid of slurry A preferably contains water, and more preferably is water.

[0078] As components that can be optionally contained in Slurry A, one or more of alkali metal compounds can be cited. From the viewpoint of promoting zeolite production, it is preferred that Slurry A contains an alkali metal compound. As the alkali metal compound, the alkali metal compounds commonly used in zeolite production can be used without any limitation. As preferred alkali metal compounds, sodium hydroxide (also referred to as "caustic soda"), potassium hydroxide, etc. can be cited. As the alkali metal compound, one kind can be used alone, or two or more kinds can be used in any proportion in combination.

[0079] The content of the liquid (preferably water) in Slurry A and the content of the alkali metal compound that can be optionally contained can be set according to the type of target zeolite. For example, in the case where water is used as the liquid for zeolite production and a sodium-containing compound is used as the alkali metal compound, it can be preferably set appropriately within the molar ratio range described in Table 2 below. It should be noted that for the liquid (preferably water), all the amounts used in zeolite production can be contained in Slurry A, or a part or all of the amounts can be added simultaneously with the addition of the silicon-containing compound X and the aluminum-containing compound Y. Regarding the addition of the liquid (preferably water), unlike the addition of the silicon-containing compound X and the aluminum-containing compound Y described later, it is not necessary to strictly control the addition amount per hour. The same applies in the case where an alkali metal compound is used for zeolite production.

[0080] The addition of the silicon-containing compound X and the addition of the aluminum-containing compound Y to Slurry A can be carried out while controlling the temperature of Slurry A within the range of 60°C to 200°C. 60°C to 200°C is the crystallization temperature of the zeolite. The temperature of Slurry A can be set according to the type of target zeolite. During the addition of the silicon-containing compound X and the addition of the aluminum-containing compound Y, the temperature of Slurry A can be kept constant, or it can also change as long as it is within the above range. The temperature control of Slurry A can be carried out by a known temperature control method such as a heater. When adding the silicon-containing compound X and when adding the aluminum-containing compound Y to Slurry A, stirring Slurry A is preferred because the contact efficiency between the zeolite seed crystals and other raw materials is improved. Stirring can be carried out using the methods commonly used in zeolite production, for example, a propeller type stirrer such as a Three-One Motor can be used.

[0081] <Silicon-containing compound X>

[0082] As the silicon-containing compound X, the silicon-containing compounds commonly used in zeolite production can be used without any limitation. As preferred silicon-containing compounds, sodium silicate (also referred to as "sodium metasilicate" or "water glass"), potassium silicate, colloidal silica, silica powder, etc. can be cited. As the silicon-containing compound, one kind can be used alone, or two or more kinds can be used in any proportion in combination.

[0083] <Aluminum-containing compound Y>

[0084] As the aluminum-containing compound Y, an aluminum-containing compound commonly used in zeolite production can be used without any limitation. Preferred aluminum-containing compounds include aluminum hydroxide, sodium aluminate (also known as "Sodium aluminate"), alumina gel, etc. As the aluminum-containing compound, one kind can be used alone, or two or more kinds can be used in any proportion.

[0085] <Total amount of raw materials>

[0086] The amounts of the liquid (preferably water) as a raw material other than the zeolite seed, the silicon-containing compound X, and the aluminum-containing compound Y, and the amount of the alkali metal compound used optionally can be set according to the type of the target zeolite. For example, when water is used as the liquid for zeolite production and a sodium-containing compound is used as the alkali metal compound, it can be preferably set appropriately within the range of the molar ratios described in Table 2 below. In Table 2, the more preferred ranges are described in parentheses. When calculating the molar ratios described in Table 2, the components from the zeolite seed are not considered. That is, the sodium content in the sodium-containing compound is calculated as a value in terms of Na2O, the silicon content in the silicon-containing compound X is calculated as a value in terms of SiO2, and the aluminum content in the aluminum-containing compound Y is calculated as a value in terms of Al2O3. Each conversion value can be obtained by calculation based on the content of each element in each raw material compound.

[0087] [Table 2]

[0088]

[0089] <Adding the silicon-containing compound X and the aluminum-containing compound Y to the slurry A>

[0090] Adding the silicon-containing compound X and the aluminum-containing compound Y to the slurry A can be carried out simultaneously or in any order. The silicon-containing compound X can be added to the slurry A directly in a liquid or solid state, or can be added to the slurry A as a solution prepared by mixing the silicon-containing compound X with a solvent. The aluminum-containing compound Y can be added to the slurry A directly in a liquid or solid form, or can be added to the slurry A as a solution prepared by mixing the aluminum-containing compound Y with a solvent.

[0091] In the case of adding both the silicon-containing compound X and the aluminum-containing compound Y simultaneously, the silicon-containing compound X and the aluminum-containing compound Y may be mixed before being added to the slurry A, or may be added to the slurry A separately without mixing before being added. For example, a solution (such as an aqueous solution) containing the silicon-containing compound X and the aluminum-containing compound Y may be prepared and added to the slurry A. On the other hand, in the case of adding the silicon-containing compound X and the aluminum-containing compound Y sequentially, either one of the additions may be started first, and either one of the additions may be ended first. The addition of the other may be started during the addition of one, or the addition of the other may be started after the addition of one is completed.

[0092] The addition of the silicon compound X to the slurry A is carried out in a manner that satisfies the following (1), and the addition of the aluminum-containing compound Y to the slurry A is carried out in a manner that satisfies the following (2). The addition carried out in a manner that satisfies the following (1) and (2) is preferred in preparing zeolite having a median particle size within the previously described range and a pore volume within the previously described range.

[0093] (1) The total addition amount of X is an amount such that the amount of silicon element in X on a mol basis is 3.5 times or more the amount of silicon element in the zeolite seed (also referred to as "X(Si) / A(Si)").

[0094] Based on the amount of silicon element in X relative to 1 mol of silicon element in the zeolite seed, the addition amount of X per hour (also referred to as "the addition amount of X(Si) per hour") is 5.00 mol or less.

[0095] (2) The total addition amount of Y is an amount such that the amount of aluminum element in Y on a mol basis is 3.5 times or more the amount of aluminum element in the zeolite seed (also referred to as "Y(Al) / A(Al)").

[0096] Based on the amount of aluminum element in Y relative to 1 mol of aluminum element in the zeolite seed, the addition amount of Y per hour (also referred to as "the addition amount of Y(Al) per hour") is 5.00 mol or less.

[0097] Regarding the addition of the silicon-containing compound X, "X(Si) / A(Si)" is 3.5 times or more, preferably 3.7 times or more, more preferably 4.0 times or more. In addition, there is no particular limitation on the upper limit of "X(Si) / A(Si)". The larger the value of "X(Si) / A(Si)", the longer the manufacturing time and the higher the manufacturing cost. Therefore, considering the manufacturing time and manufacturing cost, "X(Si) / A(Si)" is preferably 15.0 times or less, and more preferably 14.0 times or less, 13.0 times or less, 12.0 times or less in sequence.

[0098] The addition of the silicon-containing compound X is carried out such that the total addition amount is 3.5 times or more in terms of “(X(Si) / A(Si))” and the amount of silicon element in X per 1 hour is 5.00 mol or less based on 1 mol of the silicon element in the zeolite seed crystal.

[0099] Regarding the addition of the silicon-containing compound X to the slurry A, as long as the “amount of X(Si) added per 1 hour” is 5.00 mol or less, the addition can be carried out at a constant addition rate during the addition, or the addition rate can be changed during the addition. In addition, between the start of the addition and the end of the addition of the total addition amount of X, the addition can be continuously carried out without stopping, or a period including the stop of the addition can be included.

[0100] In the case where the addition of the total addition amount of X ends after 1 hour or more than 1 hour from the start of the addition, let the start of the addition be T start and the end of the addition of the total addition amount of X be T end and let T start to T end The amount of X added during any 1-hour period between them (based on the amount of silicon element in X relative to 1 mol of the silicon element in the zeolite seed crystal) is defined as the “amount of X(Si) added per 1 hour”. The above-mentioned any 1 hour may sometimes be only the addition implementation period, sometimes include the addition stop time and the addition implementation period, and sometimes be only the addition stop period. As an example, in the case where the addition of the total addition amount of X ends 80 minutes after the start of the addition, the above-mentioned any 1 hour can be, for example, the period from the start of the addition (0 minutes) to 60 minutes later, or the period from 10 minutes after the start of the addition to 70 minutes later, or the period from 20 minutes after the start of the addition to 80 minutes later. In the case where the addition of the total addition amount of X ends after 1 hour or more than 1 hour from the start of the addition, in the present invention and this specification, “the amount of X(Si) added per 1 hour is 5.00 mol or less” means that for any 1 hour starting from any moment between the start of the addition and the end of the addition, the amount of X added during this 1-hour period (based on the amount of silicon element in X relative to 1 mol of the silicon element in the zeolite seed crystal) is 5.00 mol or less.

[0101] On the other hand, in the case where the total addition amount of X is completed after T minutes (where "T minutes" is less than 60 minutes) from the start of addition and within less than 1 hour, in the present invention and this specification, "the addition amount of X (Si) per 1 hour is 5.00 mol or less" means that when the total amount of X added within T minutes is set as x mol (based on the amount of silicon element in X relative to 1 mol of silicon element in the zeolite seed crystal), the value calculated by "x × 60 / T" is 5.00 mol or less. For example, in the case where the addition of the total addition amount of X is completed 30 minutes after the start of addition and 2.00 mol of X (based on the amount of silicon element in X relative to 1 mol of silicon element in the zeolite seed crystal) is added within these 30 minutes, "x × 60 / 30" is "2.00 × 60 / 30" = 4.00 mol, and thus, the addition amount of X (Si) per 1 hour is 4.00 mol. The above-mentioned T minutes may sometimes be only the addition implementation period, and may sometimes include the addition stop time and the addition implementation period.

[0102] The addition amount of X (Si) per 1 hour is 5.00 mol or less, preferably 4.50 mol or less, and more preferably 4.00 mol or less. In addition, in the case where the addition of the total addition amount of X is completed 1 hour or more than 1 hour after the start of addition, for the addition amount of X (Si) per 1 hour, it is 0 mol when the entire 1 hour is a period of stopping addition, and it can be 0.10 mol or more or 0.50 mol or more when part or all of the 1 hour is an addition implementation period. On the other hand, in the case where the addition of the total addition amount of X is completed in less than 1 hour from the start of addition, the addition amount of X (Si) per 1 hour can be 0.10 mol or more or 0.50 mol or more, for example.

[0103] Regarding the addition of the aluminum-containing compound Y, "Y(Al) / A(Al)" is 3.5 times or more, preferably 3.7 times or more. In addition, there is no particular limitation on the upper limit of "Y(Al) / A(Al)". The larger the value of "Y(Al) / A(Al)", the longer the manufacturing time and the higher the manufacturing cost. Therefore, considering the manufacturing time and manufacturing cost, "Y(Al) / A(Al)" is preferably 12.0 times or less, and more preferably 11.0 times or less, 10.0 times or less, and 9.0 times or less in sequence.

[0104] The addition of the aluminum-containing compound Y is carried out in such a way that the total addition amount is 3.5 times or more in terms of "(Y(Al) / A(Al))", and the addition amount of Y per 1 hour (also recorded as "the addition amount of Y(Al) per 1 hour") is 5.00 mol or less based on the amount of aluminum element in Y relative to 1 mol of aluminum element in the zeolite seed crystal.

[0105] Regarding the addition of aluminum compound Y to pulp slurry A, as long as the "amount of Y(Al) added per 1 hour" is 5.00 mol or less, the addition can be carried out at a constant addition rate during the addition, or the addition rate can be changed during the addition. In addition, between the start of the addition and the end of the addition of the total amount of Y added, the addition can be continuously carried out without stopping, or a period of stopping the addition can be included.

[0106] In the case where the addition of the total amount of Y added ends after 1 hour or more than 1 hour from the start of the addition, let the start of the addition be T start , and let the end of the addition of the total amount of X added be T end , and let T start to T end The amount of Y added during any 1-hour period between them (based on the amount of aluminum element in Y relative to 1 mol of aluminum element in the zeolite seed crystal) is defined as the "amount of Y(Al) added per 1 hour". The above-mentioned any 1 hour may sometimes be only the addition implementation period, sometimes include the addition stop time and the addition implementation period, and sometimes be only the addition stop period. As an example, in the case where the addition of the total amount of Y added ends 80 minutes after the start of the addition, the above-mentioned any 1 hour can be, for example, the period from the start of the addition (0 minutes) to 60 minutes later, or the period from 10 minutes after the start of the addition to 70 minutes later, or the period from 20 minutes after the start of the addition to 80 minutes later. In the case where the addition of the total amount of Y added ends after 1 hour or more than 1 hour from the start of the addition, in the present invention and this specification, "the amount of Y(Al) added per 1 hour is 5.00 mol or less" means that for any 1 hour starting from any moment between the start of the addition and the end of the addition, the amount of Y added during this 1-hour period (based on the amount of aluminum element in Y relative to 1 mol of aluminum element in the zeolite seed crystal) is 5.00 mol or less.

[0107] On the other hand, in the case where the total addition amount of Y ends after T minutes (where "T minutes" is less than 60 minutes) from the start of addition and less than 1 hour, in the present invention and this specification, "the addition amount of Y(Al) per 1 hour is 5.00 mol or less" means that when the total amount of Y added within T minutes is set to y mol (based on the amount of aluminum element in Y relative to 1 mol of aluminum element in the zeolite seed), the value calculated by "y×60 / T" is 5.00 mol or less. For example, in the case where the addition of the total amount of Y ends 30 minutes after the start of addition and 2.00 mol of Y (based on the amount of aluminum element in Y relative to 1 mol of aluminum element in the zeolite seed) is added within these 30 minutes, "y×60 / 30" is "2.00×60 / 30" = 4.00 mol. Accordingly, the addition amount of Y(Al) per 1 hour is 4.00 mol. The above-mentioned T minutes may sometimes be only the addition implementation period, and may sometimes include the addition stop time and the addition implementation period.

[0108] The addition amount of Y(Al) per 1 hour is 5.00 mol or less, preferably 4.50 mol or less, more preferably 4.00 mol or less, and further preferably 3.50 mol or less. In addition, in the case where the addition of the total amount of Y ends 1 hour or more after the start of addition, for the addition amount of Y(Al) per 1 hour, it is 0 mol when the entire 1 hour is a period of stopping addition, and it can be 0.10 mol or more or 0.50 mol or more when part or all of the 1 hour is an addition implementation period. On the other hand, in the case where the addition of the total amount of Y ends in less than 1 hour from the start of addition, the addition amount of Y(Al) per 1 hour can be 0.10 mol or more or 0.50 mol or more, for example.

[0109] After the addition of X and Y to slurry A is completed, known post-treatment can be carried out as needed to obtain the target zeolite. For example, after the addition of X and Y to slurry A is completed, solid-liquid separation and water washing treatment are carried out, and further drying treatment is carried out, whereby the target zeolite can be obtained. The obtained zeolite can be in the form of granules, that is, zeolite particles. It should be noted that after the addition of X and Y to slurry A is completed, if the liquid temperature of the obtained mixture is further maintained at a temperature at which crystallization of the zeolite occurs, the crystallinity of the obtained zeolite can be improved, and thus it is preferred. The holding time is not particularly limited and can be appropriately set according to the type of the target zeolite and the liquid temperature of the above mixture, and can generally be in the range of 30 minutes to 24 hours.

[0110] Examples

[0111] Hereinafter, the present invention will be further described based on examples. However, the present invention is not limited to the embodiments shown in the examples.

[0112] [Example 1]

[0113] <Preparation of Slurry A>

[0114] 70 g of zeolite X (manufactured by Sinanen Zeomic Co., Ltd., silicon element content: 17.7% by mass, aluminum element content: 15.1% by mass) as a zeolite seed was dispersed in 2468 g of water. Then, 357 g of a 48% by mass sodium hydroxide solution (manufactured by Tokuyama Corporation, sodium content (in terms of Na2O): 37.2% by mass) was added to obtain Slurry A.

[0115] <Addition of X and Y, Synthesis of Zeolite>

[0116] Sodium silicate No. 3 (manufactured by Fuji Chemical Co., Ltd., silicon content (in terms of SiO2): 29.1% by mass, sodium content (in terms of Na2O): 9.4% by mass) was used as the silicon element-containing compound X, and sodium aluminate (manufactured by Asada Chemical Industry Co., Ltd., aluminum content (in terms of Al2O3): 19% by mass, sodium content (in terms of Na2O): 19.5% by mass) was used as the aluminum element-containing compound Y.

[0117] For Slurry A heated to 90 °C (the "addition temperature" in Table 3) using a hot plate, sodium silicate and sodium aluminate were added to Slurry A under the addition conditions described in Table 3 using respective metering pumps (no addition stop period, constant addition rate during addition). During the addition, Slurry A was stirred using a Three-One Motor, and the temperature of Slurry A was maintained at the addition temperature (90 °C). When the total addition amount of sodium silicate reached the amount shown in Table 3 in terms of "(X(Si) / A(Si))" and the total addition amount of sodium aluminate reached the amount shown in Table 3 in terms of "(Y(Al) / A(Al))", the addition of sodium silicate and the addition of sodium aluminate were ended simultaneously. After the addition was completed, the liquid temperature of the mixture was maintained at the addition temperature (90 °C) for 1 hour, then filtered and washed with water, and further dried to obtain zeolite particles.

[0118] [Examples 2 - 5]

[0119] As shown in Table 3, the items described in Table 3 were changed. Other than that, zeolite particles were obtained by the method described for Example 1.

[0120] [Example 6]

[0121] Slurry A prepared by the following method was used as Slurry A, and as shown in Table 3, the items described in Table 3 were changed. Other than that, zeolite particles were obtained by the method described for Example 1.

[0122] <Preparation of Slurry A>

[0123] 63 g of P-type zeolite (manufactured by Sinanen Zeomic Corporation, silicon element content: 20.8% by mass, aluminum element content: 12.4% by mass) as a zeolite seed was dispersed in 1732 g of water. Then, 75 g of a 48% by mass sodium hydroxide solution was added to obtain Slurry A.

[0124] [Example 7]

[0125] Slurry A prepared by the following method was used as Slurry A, and the items described in Table 3 were changed as shown in Table 3. Except for this, zeolite particles were obtained by the method described for Example 1.

[0126] <Preparation of Slurry A>

[0127] 129 g of A-type zeolite (manufactured by Sinanen Zeomic Corporation, silicon element content: 15.6% by mass, aluminum element content: 15.4% by mass) as a zeolite seed was dispersed in 1197 g of water. Then, 2619 g of a 48% by mass sodium hydroxide solution was added to obtain Slurry A.

[0128] [Example 8]

[0129] The items described in Table 3 were changed as shown in Table 3. For the addition of sodium silicate and sodium aluminate, it was carried out at a constant addition rate for 1 hour (the first addition period) from the start of addition, then stopped for 1 hour, and further carried out at a constant addition rate for 1 hour (the second addition period) thereafter. Except for this, zeolite particles were obtained by the method described for Example 1.

[0130] [Comparative Example 1]

[0131] The zeolite seed was 0 g. Except for this, zeolite particles were obtained by the method described for Example 1. For X and Y, the addition rate and total addition amount were set to be the same as in Example 1. However, in Comparative Example 1, since no zeolite seed was used, the addition rate and total addition amount described in Table 3 calculated based on the amount of silicon element or aluminum element contained in the zeolite seed in Slurry A could not be calculated.

[0132] [Comparative Examples 2 - 4]

[0133] The items described in Table 3 were changed as shown in Table 3. Except for this, zeolite particles were obtained by the method described for Example 1.

[0134] For Examples 1 - 8 and Comparative Examples 1 - 4, X-ray diffraction analysis was performed on the obtained zeolite particles, and as a result, it was confirmed that they were zeolites of the types shown in Table 3.

[0135] [Table 3]

[0136]

[0137] [Comparative Example 5]

[0138] The X-type zeolite using an adhesive was granulated by the method described below.

[0139] 600 g of X-type zeolite particles (manufactured by Sinanen Zeomic, particle size: 3 μm) were dispersed in 1063 g of water, and 333 g of colloidal silica (SNOWTEX ST-30 manufactured by Nissan Chemical Industries, Ltd.) as an adhesive component was further added to obtain slurry C. The obtained slurry C was spray granulated using a spray dryer (manufactured by Okawara Chemical Machinery Co., Ltd., model: L-8) to obtain a zeolite granulated product.

[0140] [Comparative Example 6]

[0141] The binder-free X-type zeolite was prepared by the method described below.

[0142] 50 g of the zeolite granulated product obtained in Comparative Example 5 was added to a plastic container containing 6 g of sodium aluminate powder (manufactured by Kishida Chemical Co., Ltd.), 58 g of a 48 mass% sodium hydroxide solution, and 175 g of water, and heated to a liquid temperature of 85°C for 17 hours while standing to obtain a binder-free zeolite in which the binder component in the zeolite particles was converted into zeolite.

[0143] [Comparative Example 7]

[0144] The pulverized product of a commercially available binder-free X-type zeolite was obtained by the method described below.

[0145] The commercially available binder-free X-type zeolite granular product (ZCI10-22 manufactured by Z-Chem) was coarsely pulverized, and sieves with 100 meshes and 300 meshes were used to obtain zeolite particles having a particle size of about 45 to 150 μm.

[0146] [Evaluation Method]

[0147] <Median particle size, pore volume, median particle size reduction rate>

[0148] For Examples 1 to 7 and Comparative Examples 1 to 7, the median particle size, pore volume, and median particle size reduction rate were determined by the method described above. The results are shown in Table 4.

[0149] <Quantification of aluminum content>

[0150] For Examples 1 to 8 and Comparative Examples 1 to 7, the aluminum content was quantified by the following method. The results are shown in Table 4. As shown in Table 4, for Examples 1 to 7, it was confirmed that the aluminum content was less than that of Comparative Examples 1 to 7. This result indicates that for the zeolite particles of Examples 1 to 7, the disintegration of the particles caused by contact with water was suppressed.

[0151] 5 g of zeolite particles and 50 g of activated carbon (manufactured by Kowa Chemical Co., Ltd.) were mixed using a mixer. The resulting mixture was put into a beaker containing 300 ml of simulated tap water (leaching solution specified in JIS S3200-7:2010: pH 7.0 ± 0.1, hardness 45 ± 5 mg / L, alkalinity 35 ± 5 mg / L, residual chlorine 0.3 mg ± 0.1 mg / L), and stirred for 24 hours using a propeller stirrer. After 24 hours, solid-liquid separation was performed using No. 5A filter paper (pore size 7 μm) manufactured by Advantech Co., Ltd., and the aluminum content in the filtrate was quantified by atomic absorption spectrometry, and the concentration (unit: ppb (mass basis)) was calculated. The results are shown in Table 4.

[0152] <Heavy metal adsorption test 1>

[0153] For the examples and comparative examples shown in Table 5, the lead adsorption test was performed by the following method. The results are shown in Table 5.

[0154] 50 mg of an adsorbent (zeolite particles) was weighed in a polypropylene container, and 500 ml of simulated tap water containing 10,000 ppb (mass basis) of lead ions was added thereto, and stirred (rotation speed: 150 rpm) for 24 hours (adsorption treatment) using a propeller stirrer.

[0155] After stirring for 24 hours, solid-liquid separation was performed using a membrane filter (pore size: 0.45 μm), and the lead ion concentration in the separated liquid was measured using an atomic absorption spectrophotometer. The lead removal rate was calculated according to the following calculation formula.

[0156] Lead removal rate (%) = ((a - b) / a) × 100 (%)

[0157] a: Lead ion concentration before adding the adsorbent (10,000 ppb)

[0158] b: Lead ion concentration after adding the adsorbent and stirring (adsorption treatment) for 24 hours

[0159] 50 mg of the adsorbent (zeolite particles) of Example 1 was weighed in a polypropylene container, and 500 ml of simulated tap water containing any one of copper ions, zinc ions, or cadmium ions at 2,500 ppb (mass basis) was added thereto, and stirred (rotation speed: 150 rpm) for 24 hours (adsorption treatment) using a propeller stirrer.

[0160] After stirring for 24 hours, solid-liquid separation was carried out using a membrane filter (pore size: 0.45 μm), and the concentrations of copper ions, zinc ions, or cadmium ions in the separated liquid were measured with an atomic absorption photometer. The lead removal rate was calculated according to the following calculation formula. The results are shown in Table 6.

[0161] Removal rate (%) = ((a - b) / a) × 100 (%)

[0162] a: Metal ion concentration before adding the adsorbent (2500 ppb)

[0163] b: Metal ion concentration after adding the adsorbent and stirring (adsorption treatment) for 24 hours

[0164] As is well known, zeolite has the function of adsorbing various heavy metals. Therefore, examples other than those shown in Table 5 and Table 6, which show the test results, also certainly have the heavy metal adsorption ability.

[0165] [Table 4]

[0166]

[0167] [Table 5]

[0168]

[0169] [Table 6]

[0170]

[0171] One aspect of the present invention is useful in various water purification fields such as the purification of tap water.

Claims

1. A heavy metal adsorbent comprising zeolite, wherein the median particle size of the zeolite based on volume is 10.0 μm or more and 60.0 μm or less, and the pore volume measured in the pore volume calculation range of 10 nm to 1000 nm by mercury intrusion porosimetry is 0.1000 cm 3 / g or less, The reduction rate of the median particle size of the zeolite after ultrasonic treatment at an output power of 40 W for 600 seconds is 20.0% or less. The zeolite is selected from zeolite X, zeolite Y, and zeolite P.

2. The heavy metal adsorbent according to claim 1, wherein the median particle size is 20.0 μm or more and 50.0 μm or less.

3. The heavy metal adsorbent according to claim 1, wherein The fine pore volume is 0.0200 cm 3 / g or less.

4. The heavy metal adsorbent according to claim 1, wherein the zeolite is zeolite X.

5. The heavy metal adsorbent according to claim 1, wherein the heavy metal is one or more heavy metals selected from lead, copper, zinc, and cadmium.

6. The heavy metal adsorbent according to claim 1, wherein the median particle size is 20.0 μm or more and 50.0 μm or less, The pore volume is 0.0200 cm 3 / g or less, the zeolite is zeolite X, and the heavy metal is one or more heavy metals selected from lead, copper, zinc, and cadmium.

7. A water purification material comprising the heavy metal adsorbent according to any one of claims 1 to 6.

8. A method for manufacturing a heavy metal adsorbent, which is a method for manufacturing the heavy metal adsorbent according to any one of claims 1 to 6, the method comprising: adding a silicon compound X and an aluminum compound Y to a zeolite seed slurry A at a temperature in the range of 60°C to 200°C simultaneously or in any order, the addition of X satisfies the following (1), and the addition of Y satisfies the following (2): (1) The total addition amount of X is such that the amount of silicon element in X in terms of mol is 3.5 times or more the amount of silicon element in the zeolite seed, based on the amount of silicon element in X per 1 mol of silicon element in the zeolite seed, the addition amount of X per 1 hour is 5.00 mol or less; (2) The total addition amount of Y is such that the amount of aluminum element in Y in terms of mol is 3.5 times or more the amount of aluminum element in the zeolite seed, based on the amount of aluminum element in Y per 1 mol of aluminum element in the zeolite seed, the addition amount of Y per 1 hour is 5.00 mol or less.

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