HEAVY METAL ADSORBENT, WATER PURIFICATION MATERIAL, AND METHOD OF MANUFACTURING HEAVY METAL ADSORBENT

Abstract

Provided is a heavy metal adsorbent consisting of a zeolite with a median diameter on a volume basis of 10.0 ?m or more and a pore volume measured in a pore volume calculation range of 10 nm to 1000 nm by a mercury intrusion method of 0.1000 cm.sup.3/g or less.

Claims

1.-9. (canceled)

10. A method of manufacturing a heavy metal adsorbent consisting of a zeolite with a median diameter on a volume basis of 10.0 m or more and a pore volume measured in a pore volume calculation range of 10 nm to 1000 nm by a mercury intrusion method of 0.1000 cm.sup.3/g or less, which comprises: adding a silicon-containing compound X and an aluminum-containing compound Y to a zeolite seed crystal-containing slurry A at a temperature of 60? C. to 200? C. simultaneously or in any order, wherein the addition of X satisfies the following (1), and the addition of Y satisfies the following (2): (1) a total addition amount of X is an amount such that a silicon element amount in X is 3.5 or more times amount of a silicon element amount in the zeolite seed crystals on a molar basis, and an addition amount of X per hour is 5.00 mol or less based on the silicon element amount in X with respect to 1 mol amount of silicon elements in the zeolite seed crystals; and (2) a total addition amount of Y is an amount such that an aluminum element amount in Y is 3.5 or more times amount of an aluminum element amount in the zeolite seed crystals on a molar basis, and an addition amount of Y per hour is 5.00 mol or less based on the aluminum element amount in Y with respect to 1 mol amount of aluminum elements in the zeolite seed crystals.

11. The method of manufacturing a heavy metal adsorbent according to claim 10, wherein a median diameter reduction rate of the zeolite after 600-second ultrasonication at an output of 40 W is 20% or less.

12. The method of manufacturing a heavy metal adsorbent according to claim 10, wherein the median diameter of the zeolite is 20.0 ?m or more and 50.0 ?m or less.

13. The method of manufacturing a heavy metal adsorbent according to claim 10, wherein the pore volume of the zeolite is 0.0200 cm.sup.3/g or less.

14. The method of manufacturing a heavy metal adsorbent according to claim 10, wherein the zeolite is selected from the group consisting of Type-A zeolite, Type-X zeolite, Type-Y zeolite, and Type-P zeolite.

15. The method of manufacturing a heavy metal adsorbent according to claim 10, wherein the zeolite is Type-X zeolite.

16. The method of manufacturing a heavy metal adsorbent according to claim 10, wherein the heavy metal is at least one heavy metal selected from the group consisting of lead, copper, zinc, and cadmium.

17. The method of manufacturing a heavy metal adsorbent according to claim 10, wherein a median diameter reduction rate of the zeolite after 600-second ultrasonication at an output of 40 W is 20% or less, the median diameter of the zeolite is 20.0 ?m or more and 50.0 ?m or less, the pore volume of the zeolite is 0.0200 cm.sup.3/g or less, the zeolite is Type-X zeolite, and the heavy metal is at least one heavy metal selected from the group consisting of lead, copper, zinc, and cadmium.

Description

EXAMPLES

[0103] The present invention will be further described with reference to Examples. However, the present invention is not limited to the embodiments shown in the Examples.

Example 1

<Preparation of Slurry A>

[0104] As zeolite seed crystals, 70 g of Type-X zeolite (manufactured by Sinanen Zeomic Co., Ltd., silicon element content: 17.7 mass %, aluminum element content: 15.1 mass %) was dispersed in 2468 g of water, and then 357 g of 48 mass % sodium hydroxide solution (manufactured by Tokuyama Corporation, sodium content (in terms of Na.sub.2O): 37.2 mass %) was added to prepare a slurry A.

[0105] <Addition of X, Y and Synthesis of Zeolite>

[0106] No. 3 soda silicate (manufactured by Fuji Chemical Co., Ltd., silicon content (in terms of SiO.sub.2): 29.1 mass %, sodium content (in terms of Na.sub.2O): 9.4 mass %) was used as a silicon element-containing compound X, and soda aluminate (manufactured by Asada Chemical Industry Co., Ltd., aluminum content (in terms of Al.sub.2O.sub.3): 19 mass %, sodium content (in terms of Na.sub.2O): 19.5 mass %) was used as an aluminum element-containing compound Y.

[0107] To a slurry A heated at 90? C. (addition temperature in Table 3) on a hotplate, soda silicate and soda aluminate were simultaneously added to a slurry A using separate metering pumps under the addition condition listed in Table 3 (addition-suspended period: none, addition rate during addition: constant). During the addition, the slurry A was stirred by a three-one motor, and the temperature of the slurry A was kept at the addition temperature (90? C.). The addition of soda silicate and the addition of soda aluminate were simultaneously finished at the time when the total addition amount of soda silicate reached an amount listed in Table 3 indicated as (X(Si)/A(Si)) and the total addition amount of soda aluminate reached the amount listed in Table 3 indicated as (Y(Al)/A(Al)). After the addition, the liquid temperature of the mixture was kept at the addition temperature (90? C.) for one hour, then the mixture was filtrated and washed with water, and further dried to produce zeolite particles.

Examples 2 to 5

[0108] Zeolite particles were prepared by the method described in Example 1, except that the items listed in Table 3 were changed as listed in Table 3.

Example 6

[0109] Zeolite particles were prepared by the method described in Example 1, except that the slurry A prepared by the method described below was used as the slurry A, and the items listed in Table 3 were changed as listed in Table 3.

<Preparation of Slurry A>

[0110] As zeolite seed crystals, 63 g of Type-P zeolite (manufactured by Sinanen Zeomic Co., Ltd., silicon element content: 20.8 mass %, aluminum element content: 12.4 mass %) was dispersed in 1732 g of water, and then 75 g of 48 mass % sodium hydroxide solution was added to prepare slurry A.

Example 7

[0111] Zeolite particles were prepared by the method described in Example 1, except that the slurry A prepared by the method described below was used as the slurry A, and the items listed in Table 3 were changed as listed in Table 3.

<Preparation of Slurry A>

[0112] As zeolite seed crystals, 129 g of Type-A zeolite (manufactured by Sinanen Zeomic Co., Ltd., silicon element content: 15.6 mass %, aluminum element content: 15.4 mass %) was dispersed in 1197 g of water, and then 2619 g of 48 mass % sodium hydroxide solution was added to prepare a slurry A.

Example 8

[0113] Zeolite particles were prepared by the method described in Example 1, except that the items listed in Table 3 were changed as listed in Table 3, and the addition of soda silicate and soda aluminate was performed at a constant addition rate within a period from the start of addition to one hour later from the start of addition (first addition period), the addition was thereafter suspended for one hour, and then the addition was performed at a constant addition rate for another one hour (second addition period).

Comparative Example 1

[0114] Zeolite particles were prepared by the method described in Example 1, except that the amount of the zeolite seed crystals was 0 g. Regarding X and Y, the addition rate and total addition amount thereof were set to be the same as in Example 1. However, since zeolite seed crystals were not used in Comparative Example 1, the addition rate and the total addition amount listed in Table 3 calculated based on the silicon element amount or aluminum element amount in zeolite seed crystals in the slurry A cannot be calculated for Comparative Example 1.

Comparative Examples 2 to 4

[0115] Zeolite particles were prepared by the method described in Example 1, except that the items listed in Table 3 were changed as listed in Table 3.

[0116] X-ray diffraction analysis of zeolite particles obtained in each of Examples 1 to 8 and Comparative Examples 1 to 4 revealed that the zeolite particles were zeolites of the types listed in Table 3.

TABLE-US-00003 TABLE 3 Type of Addition Addition X(Si)/ Y(Al)/ Zeolite Type of amount of amount of A(Si) A(Al) seed resulting X(Si) per Y(Al) per [Times [Times Addition crystals zeolite hour [mol] hour [mol] amount] amount] temperature Example 1 Type X Type X 1.59 1.27 7.9 6.4 90? C. Example 2 Type X Type X 1.59 1.27 4.8 3.8 90? C. Example 3 Type X Type X 3.97 3.18 7.9 6.4 90? C. Example 4 Type X Type X 1.59 1.27 11.1 8.9 90? C. Example 5 Type X Type X 0.79 0.64 7.9 6.4 70? C. Example 6 Type P Type P 2.45 1.57 9.8 6.3 95? C. Example 7 Type A Type A 0.93 0.91 3.7 3.6 85? C. Example 8 Type X Type X First First 7.9 6.4 90? C. addition addition period: period: 3.18 2.54 Second Second addition addition period: period: 1.59 1.27 Comparative No seed Type X 90? C. Example 1 crystal Comparative Type X Type X 0.98 0.71 3.4 2.5 90? C. Example 2 Comparative Type X Type X 1.59 1.27 7.9 6.4 40? C. Example 3 Comparative Type X Type X 7.94 6.35 7.9 6.4 90? C. Example 4

Comparative Example 5

[0117] Type-X zeolite using a binder was granulated by the method described below.

[0118] Type-X zeolite particles (manufactured by Sinanen Zeomic Co., Ltd., particle size: 3 ?m), 600 g, were dispersed in 1063 g of water, and 333 g of colloidal silica (SNOWTEX ST-30, manufactured by Nissan Chemical Corporation) was further added as a binder component to prepare a slurry C. The resulting slurry C was spray-granulated using a spray dryer (model: L-8, manufactured by Ohkawara Kakoki Co., Ltd.) to prepare a granulated zeolite.

Comparative Example 6

[0119] Binderless Type-X zeolite was prepared by the method described below.

[0120] The granulated zeolite prepared in Comparative Example 5, 50 g, was added to a plastic container containing 6 g of sodium aluminate powder (manufactured by Kishida Chemical Co., Ltd.), 58 g of 48 mass % sodium hydroxide solution, and 175 g of water, and the resulting mixture was heated at a liquid temperature of 85? C. for 17 hours under a static condition to prepare binderless zeolite in which a binder component in zeolite particles was converted into zeolites.

Comparative Example 7

[0121] A pulverized material of a commercially available binderless Type-X zeolite was prepared by the method described below.

[0122] Commercially available binderless Type-X zeolite granulated product (ZCI 10-22, manufactured by Z-Chemicals Inc.) was coarsely pulverized to prepare zeolite particles with a particle size of about 45 to 150 ?m using 100-mesh and 300-mesh sieves.

[0123] [Evaluation Method]

<Median Diameter, Pore Volume, and Median Diameter Reduction Rate>

[0124] Regarding Examples 1 to 7 and Comparative Examples 1 to 7, median diameters, pore volumes, and median diameter reduction rates were determined by the abovementioned method. Table 4 shows the results.

[0125] <Determination of Aluminum Amount>

[0126] The aluminum amount of each of Examples 1 to 8 and Comparative Examples 1 to 7 was determined by the method described below. Table 4 shows the results. As indicated in Table 4, the aluminum amounts in Examples 1 to 7 were found to be smaller than in Comparative Examples 1 to 7. Such results indicate that particle disintegration due to contact with water is suppressed in zeolite particles of Examples 1 to 7.

[0127] Zeolite particles, 5 g, and activated carbon (manufactured by Kowa Kagaku Kogyo K.K.), 50 g, were mixed using a mixer. The resulting mixture was put in a beaker containing 300 ml of simulated tap water (leachate specified in JIS S 3200-7:2010: 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 with a propeller stirrer for 24 hours. After 24 hours, the resulting mixture was subjected to solid-liquid separation using Advantec No. 5A filter paper (pore size: 7 ?m), and the aluminum content in the filtrate was determined by atomic absorption spectrophotometry to calculate the concentration (unit: ppb (on a mass basis)). Table 4 shows the results.

[0128] <Heavy Metal Adsorption Test 1>

[0129] Lead adsorption test was performed on Examples and Comparative Example listed in Table 5 by the method described below. Table 5 shows the results.

[0130] In a polypropylene container, 50 mg of an adsorbent (zeolite particles) was weighed, 500 ml of simulated tap water containing 10000 ppb (on a mass basis) of lead ions was added thereto, and the mixture was stirred for 24 hours using a propeller stirrer (number of revolutions: 150 rpm) (adsorption process).

[0131] After the 24-hour stirring, the resulting mixture was subjected to solid-liquid separation using a membrane filter (pore size: 0.45 ?m), and the lead ion concentration in the separated liquid was measured by an atomic absorption spectrophotometer. Lead removal rates were determined according to the expression described below.

Lead removal rate (%)=((a?b)/a)?100(%) [0132] a: Lead ion concentration before the addition of an adsorbent (10000 ppb) [0133] b: Lead ion concentration after adding an adsorbent and stirring for 24 hours (adsorption process)

[0134] <Heavy Metal Adsorption Test 2>

[0135] In a polypropylene container, 50 mg of an adsorbent in Example 1 (zeolite particles) was weighed, 500 ml of simulated tap water containing 2500 ppb (on a mass basis) of any one of copper ions, zinc ions, or cadmium ions was added thereto, and the mixture was stirred for 24 hours using a propeller stirrer (number of revolutions: 150 rpm) (adsorption process).

[0136] After 24-hour stirring, the resulting mixture was subjected to solid-liquid separation using a membrane filter (pore size: 0.45 ?m), and the concentration of copper ions, zinc ions, or cadmium ions in the separated liquid was measured by an atomic absorption spectrophotometer. Lead removal rates were determined according to the expression described below. Table 6 shows the results.

Removal rate (%)=((a?b)/a)?100(%) [0137] a: Metal ion concentration before the addition of an adsorbent (2500 ppb) [0138] b: Metal ion concentration after adding an adsorbent and stirring for 24 hours (adsorption process)

[0139] As widely known, zeolite has a function that adsorbs various heavy metals. Accordingly, it goes without saying that Examples other than the Examples, the test results of which are listed in Tables 5 and 6, have heavy metal adsorption abilities, similarly.

TABLE-US-00004 TABLE 4 Pore volume Median Calculation diameter range: Reduc- Alum- Median 10 nm to A B tion inum diameter 1000 nm value value rate amount [?m] [cm.sup.3/g] [?m] [?m] [%] [ppb] Example 1 27.9 0.0047 27.9 26.7 4.3 30 Example 2 22.3 0.0437 24.8 20.2 18.5 40 Example 3 24.9 0.0190 25.5 22.1 13.3 25 Example 4 50.3 0.0069 52.1 46.7 10.4 31 Example 5 29.2 0.0080 29.5 25.3 14.2 89 Example 6 35.3 0.0031 36.1 34.9 3.3 27 Example 7 54.2 0.0135 58.5 51.1 12.6 59 Example 8 26.5 0.0053 27.3 25.5 6.6 35 Comparative 3.9 0.1863 8.9 3.2 64.0 839 Example 1 Comparative 15.4 0.1110 23.9 7.9 66.9 450 Example 2 Comparative 9.3 0.2981 15.3 8.6 43.8 637 Example 3 Comparative 11.5 0.1451 19.3 7.8 59.5 346 Example 4 Comparative 52.5 0.1748 111.0 6.2 94.4 520 Example 5 Comparative 33.3 0.3869 44.5 17.7 60.2 257 Example 6 Comparative 41.6 0.4435 44.0 10.2 76.8 340 Example 7

TABLE-US-00005 TABLE 5 Lead ion concentration Lead removal after adsorption process rate (ppb) (%) Example 1 5 99.95 Example 3 2 99.98 Example 6 10 99.90 Comparative 5 99.95 Example 1 Example 7 15 99.85

TABLE-US-00006 TABLE 6 Copper ion Zinc ion Cadmium ion Concentration Concentration Concentration after after after adsorption Removal adsorption Removal adsorption Removal process rate process rate process rate (ppb) (%) (ppb) (%) (ppb) (%) Example 1 5 99.80 20 99.20 1 99.96

[0140] One aspect of the present invention is useful in various water purification fields such as tap water purification.