Adsorption method for at least one of cesium and strontium employing silicotitanate having sitinakite structure
11471855 · 2022-10-18
Assignee
Inventors
- Yoju SHIMIZU (Yamaguchi, JP)
- Hajime Funakoshi (Yamaguchi, JP)
- Keisuke TOKUNAGA (Yamaguchi, JP)
- Shigeru Hirano (Yamaguchi, JP)
- Takashi Sakuma (Tokyo, JP)
- Makoto Komatsu (Tokyo, JP)
- Takeshi Izumi (Tokyo, JP)
Cpc classification
B01J20/3007
PERFORMING OPERATIONS; TRANSPORTING
B01J20/28011
PERFORMING OPERATIONS; TRANSPORTING
International classification
B01J20/30
PERFORMING OPERATIONS; TRANSPORTING
Abstract
The present invention provides a composition that includes a silicotitanate that has a sitinakite structure, the composition having higher cesium adsorptivity than conventional compositions. The present invention also provides a production method for the composition that includes a silicotitanate that has a sitinakite structure. The production method does not require the use of hazardous or deleterious materials, can generate a product using a compound that is easily acquired, and can use a general-purpose autoclave. Also provided is a silicotitanate composition that has higher strontium adsorptivity than the present invention. Provided is a silicotitanate composition that contains niobium and a silicotitanate that has a sitinakite structure, the composition having at least two or more diffraction peaks selected from the group consisting of 2θ=8.8°±0.5°, 2θ=10.0°±0.5°, and 2θ=29.6°±0.5°.
Claims
1. An adsorption method for at least one of cesium and strontium, comprising contacting a medium containing at least one of cesium and strontium with a silicotitanate composition, wherein the silicotitanate composition comprises a silicotitanate having a sitinakite structure and niobium, and has at least two or more diffraction peaks at X-ray diffraction (XRD) angles selected from the group consisting of 2θ=8.8±0.5°, 2θ=10.0±0.5°, and 2θ=29.6±0.5°, wherein the silicotitanate composition has at least X-ray diffraction angles 20 and X-ray diffraction peak intensity ratios that are shown in the following Table: TABLE-US-00023 TABLE 1 X-RAY DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 8.8 ± 0.5 5 OR MORE AND 20 OR LESS 10.0 ± 0.5 5 OR MORE AND 20 OR LESS 11.3 ± 0.5 100 29.6 ± 0.5 5 OR MORE AND 40 OR LESS and wherein the medium containing at least one of cesium and strontium is at least one of soil, waste materials, seawater, or groundwater.
2. The adsorption method according to claim 1, wherein the silicotitanate composition comprises a crystalline substance having at least two or more diffraction peaks at X-ray diffraction angles selected from the group consisting of 2θ=8.8±0.5°, 2θ=10.0±0.5° and 2θ=29.6±0.5°.
3. The adsorption method according to claim 2, wherein the crystalline substance is a niobate.
4. An adsorption method for at least one of cesium and strontium, comprising contacting a medium containing at least one of cesium and strontium with a silicotitanate composition, wherein the silicotitanate composition comprises a silicotitanate having a sitinakite structure and niobium, and has at least diffraction peaks at X-ray diffraction (XRD) angles of 2θ=27.8±0.5° and 2θ=29.4±0.5°, wherein the silicotitanate composition has at least X-ray diffraction angles 2θ and X-ray diffraction peak intensity ratios that are shown in the following table: TABLE-US-00024 TABLE 2 X-RAY DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 11.3 ± 0.5 100 27.8 ± 0.5 30 OR MORE AND 70 OR LESS 29.4 ± 0.5 30 OR MORE AND 70 OR LESS and wherein the medium containing at least one of cesium and strontium is at least one of soil, waste materials, seawater, or groundwater.
5. The adsorption method according to claim 4, wherein the silicotitanate composition comprises a crystalline substance having at least diffraction peaks at X-ray diffraction angles of 2θ=27.8±0.5° and 2θ=29.4±0.5°.
6. The adsorption method according to claim 5, wherein the crystalline substance is a silicotitanate having a vinogradovite structure.
Description
BRIEF DESCRIPTION OF DRAWINGS
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EXAMPLES
(26) Hereinafter, the present invention will be described specifically with reference to Examples. However, the present invention is not limited to these Examples.
(27) (Powder X-Ray Diffraction Measurement)
(28) An XRD pattern of a sample was measured using a general X-ray diffractometer (trade name: MXP3HF-type X-ray diffractometer, manufactured by MAC Science Co. Ltd.). Measurement conditions are as follows.
(29) Radiation source: CuKα-ray (λ=1.5405 Å)
(30) Measurement mode: step scan
(31) Scan condition: 0.04°/second
(32) Divergence slit: 1.00 deg.
(33) Scattering slit: 1.00 deg.
(34) Receiving slit: 0.30 mm
(35) Measurement time: 3.00 seconds
(36) Measurement range: 2θ=5.0° to 60.0°
(37) A sitinakite structure was identified by comparison of the obtained XRD pattern with XRD peaks of silicotitanate of sitinakite structure described in Reference Document 1 or 2 or Reference HP.
(38) (Composition Analysis of Silicotitanate Composition)
(39) The composition analysis of a crystallized product was measured by a general ICP method. In the measurement, a general ICP-AES (device name: OPTIMA3000DV, manufactured by PerkinElmer Inc.) was used.
(40) (Measurement of Sr and Cs Ion Concentrations)
(41) As a medium to be treated, an aqueous solution containing at least any of Cs and Sr and metal ions that simulated seawater components (hereinafter also referred to as “simulated seawater”) was prepared, and subjected to an adsorption treatment. The aqueous solution was appropriately diluted, and the Sr ion concentration in the aqueous solution was measured by the ICP method. In the measurement, a general ICP-AES (device name: OPTIMA3000DV, manufactured by PerkinElmer Inc.) was used. The concentrations of Ca, Mg, Na, and K were measured in the same manner.
(42) The Cs concentration in the aqueous solution was measured by ICP-MASS (device name: NExION300S, manufactured by PerkinElmer Inc.).
(43) From the obtained concentration of each metal, Kd of each metal was calculated.
(44) (Removal Ratio of Metal)
(45) The removal ratio of each metal by the adsorption treatment was determined by the following equation (2):
Removal ratio=(C.sub.0−C)/C.sub.0×100 (2).
(46) C.sub.0: metal ion concentration in metal ion-containing aqueous solution before adsorption treatment (ppm)
(47) C: metal ion concentration in metal ion-containing aqueous solution in adsorption equilibration (ppm)
(48) (Measurement of Particle Diameter Distribution)
(49) A cumulative curve of particle diameter distribution was measured by light-scattering particle size distribution measurement. In the measurement, a general light-scattering particle diameter distribution measurement device (MICROTRAC HRA MODEL: 9320-X1000 manufactured by NIKKISO CO., LTD.) was used. As a pre-treatment, a sample was suspended in distilled water and dispersed by an ultrasonic homogenizer for 2 minutes. From the obtained cumulative curve of particle diameter distribution, the average particle diameter and the cumulative value at which the particle diameter was 10 μm were obtained.
(50) (Observation of Particles)
(51) The particles of the sample were observed by a general scanning electron microscope (device name: JSM-6390LV, manufactured by JEOL Ltd.).
Example 1
(52) 20 g of sodium silicate (SiO.sub.2; 29.1% by weight), 46 g of an aqueous solution of titanium sulfate (TiO.sub.2; 13.31% by weight), 50 g of sodium hydroxide (NaOH; 48% by weight), and 77 g of pure water were mixed to obtain a raw material mixture of the following composition.
(53) Si/Ti mole ratio=1.31
(54) Na/Ti mole ratio=3.3
(55) H.sub.2O/Ti mole ratio=82
(56) The obtained raw material mixture was in a gel form.
(57) A part of the obtained raw material mixture was collected, separated into a solid and a liquid, washed with hot water, and dried in the air at 80° C., to obtain the raw material mixture in a powder form. An XRD chart of the powder of the raw material mixture is shown in
(58) The raw material mixture in the gel form was charged in a stainless steel autoclave (trade name: KH-02, manufactured by HIRO COMPANY) with stirring. The raw material mixture was crystallized by heating at 180° C. for 72 hours, to obtain a crystallized product.
(59) The pressure during crystallization was 0.8 MPa, which corresponded to a water vapor pressure at 180° C. The crystallized product was cooled, filtered, washed, and dried to obtain a silicotitanate composition in a powder form.
(60) From an XRD chart of the obtained silicotitanate composition, a peak attributable to a component other than a sitinakite structure was not confirmed. The silicotitanate composition of this example was confirmed to be a single phase of S-type silicotitanate. The XRD chart of the silicotitanate composition of this example is shown in
(61) The Si/Ti mole ratio of the obtained silicotitanate composition was 0.68, and the Na/Ti mole ratio was 1.07. Results of composition analysis of the obtained silicotitanate composition are shown in Table 6.
Example 2
(62) A crystallized product was obtained in the same manner as in Example 1 except that a raw material mixture had the following composition.
(63) Si/Ti mole ratio=1.25
(64) Na/Ti mole ratio=3.6
(65) H.sub.2O/Ti mole ratio=82
(66) The obtained raw material mixture was an amorphous silicotitanate gel, and the pressure during crystallization was 0.8 MPa. The crystallized product was cooled, filtered, washed, and dried to obtain a silicotitanate composition in a powder form.
(67) From an XRD chart of the obtained silicotitanate composition, an XRD peak attributable to a component other than a sitinakite structure was not confirmed. The silicotitanate composition of this example was confirmed to be a single phase of S-type silicotitanate. The XRD chart of the silicotitanate composition of this example is shown in
(68) The Si/Ti mole ratio of the obtained silicotitanate composition was 0.75, and the Na/Ti mole ratio was 1.31. Results of composition analysis of the obtained silicotitanate composition are shown in Table 6.
(69) (Evaluation of Sr Adsorption Properties)
(70) For the obtained silicotitanate composition, the Sr selective adsorption properties from simulated seawater were evaluated. As the simulated seawater containing Sr, an aqueous solution containing the following composition was prepared using NaCl, MgCl.sub.2, CaCl.sub.2, Na.sub.2SO.sub.4, KCl, and a Sr standard solution. This aqueous solution was used as a measurement solution.
(71) Na: 870 ppm by weight (derived from NaCl)
(72) Mg: 118 ppm by weight
(73) Ca: 41 ppm by weight
(74) Na: 126 ppm by weight (derived from Na.sub.2SO.sub.4)
(75) K: 32 ppm by weight
(76) Sr: 1 ppm by weight
(77) (Herein, the total concentration of Na was 996 ppm by weight)
(78) To 1 L of the measurement solution, 0.05 g of the silicotitanate composition was added, and the mixture was mixed with stirring at 25° C. and 800 rpm for 24 hours. Thus, the adsorption properties were evaluated. As a pre-treatment, the silicotitanate composition was heated at 100° C. in the air for 1 hour. After mixing, the silicotitanate composition was separated from the measurement solution by filtration. The Sr concentration in the collected measurement solution was measured.
(79) From the concentration of each component in the measurement solution after the evaluation of the adsorption properties, Kd.sub.(Sr) was determined by the aforementioned equation (1), and the removal ratio was determined by the aforementioned equation (2).
(80) After the evaluation of the adsorption properties, the Sr concentration in the measurement solution was 0.52 ppm by weight, the calcium concentration was 38 ppm by weight, and the magnesium concentration was 110 ppm by weight. Kd of each metal was as follows.
(81) Kd.sub.(Sr): 18,000 mL/g
(82) Kd.sub.(Ca): 1,600 mL/g
(83) Kd.sub.(Mg): 1,500 mL/g
(84) The removal ratio of each metal was as follows.
(85) Sr: 48%
(86) Ca: 7.3%
(87) Mg: 6.8%
(88) Therefore, Kd.sub.(Sr) was 10,000 mL/g or more, and was larger than Kd.sub.(Ca) and Kd.sub.(Mg). The Sr removal ratio was larger than calcium and magnesium removal ratios. The silicotitanate composition of this example was confirmed to have Sr adsorption selectivity in the coexistence of seawater component.
(89) (Evaluation of Cs Adsorption Properties)
(90) For the obtained silicotitanate composition, the Cs selective adsorption properties from simulated seawater were evaluated. As simulated seawater containing Cs, an aqueous solution containing the following composition was prepared using NaCl, MgCl.sub.2, CaCl.sub.2, Na.sub.2SO.sub.4, KCl, and a Cs standard solution. This aqueous solution was used as a measurement solution.
(91) Na: 1,740 ppm by weight (derived from NaCl)
(92) Mg: 236 ppm by weight
(93) Ca: 82 ppm by weight
(94) Na: 252 ppm by weight (derived from Na.sub.2SO.sub.4)
(95) K: 64 ppm by weight
(96) Cs: 1 ppm by weight
(97) (Herein, the total concentration of Na was 1,992 ppm by weight)
(98) To 1 L of the measurement solution, 0.05 g of the silicotitanate composition was added, and the mixture was mixed with stirring at 25° C. and 800 rpm for 24 hours. As a pre-treatment, the silicotitanate composition was heated at 100° C. in the air for 1 hour. After mixing, the silicotitanate composition was separated from the measurement solution by filtration. The Cs concentration in the collected measurement solution was measured.
(99) After the evaluation of the adsorption properties, the Cs concentration in the measurement solution was 0.08 ppm by weight.
(100) From the concentration of each component in the measurement solution after the evaluation of the adsorption properties, Kd.sub.(Cs) was determined by the aforementioned equation (1), and the removal ratio was determined by the aforementioned equation (2).
(101) Kd.sub.(Cs) was 230,000 mL/g. The Cs removal ratio was 92%. In the silicotitanate composition of this example, Kd.sub.(Cs) was 100,000 mL/g or more, and the Cs removal ratio was larger. Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 6.
Example 3
(102) A crystallized product was obtained in the same manner as in Example 1 except that a raw material mixture had the following composition.
(103) Si/Ti mole ratio=1.14
(104) Na/Ti mole ratio=4.0
(105) H.sub.2O/Ti mole ratio=82
(106) The obtained raw material mixture was an amorphous silicotitanate gel, and the pressure during crystallization was 0.8 MPa. The crystallized product was cooled, filtered, washed, and dried to obtain a silicotitanate composition in a powder form.
(107) From an XRD chart of the obtained silicotitanate composition, an XRD peak attributable to a component other than a sitinakite structure was not confirmed. The silicotitanate composition of this example was confirmed to be a single phase of S-type silicotitanate. The XRD chart of the silicotitanate composition of this example is shown in
(108) The Si/Ti mole ratio of the obtained silicotitanate composition was 0.72, and the Na/Ti mole ratio was 1.25. Results of composition analysis of the obtained silicotitanate composition are shown in Table 6.
Example 4
(109) 20 g of sodium silicate (SiO.sub.2; 29.1% by weight), 71 g of an aqueous solution of titanium oxysulfate (TiOSO.sub.4; 8.2% by weight), 63 g of sodium hydroxide (NaOH; 48% by weight), and 41 g of pure water were mixed to obtain an amorphous silicotitanate gel of the following composition.
(110) Si/Ti mole ratio=1.34
(111) Na/Ti mole ratio=3.3
(112) H.sub.2O/Ti mole ratio=82
(113) To the obtained amorphous silicotitanate gel, a silicotitanate having a crystal of sitinakite structure was added as a seed crystal in an amount of 1% by weight relative to the amorphous silicotitanate gel. Subsequently, the gel was crystallized in the same manner as in Example 1. The crystallized product was further cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(114) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 5. The XRD pattern is shown in
(115) TABLE-US-00005 TABLE 5 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 11.4 100 27.6 39
(116) The Sr and Cs selective adsorption properties of the silicotitanate composition obtained in this example were evaluated using simulated seawater containing Sr and Cs as a medium to be treated. As the simulated seawater, an aqueous solution containing the following composition was prepared using NaCl, MgCl.sub.2, CaCl.sub.2, Na.sub.2SO.sub.4, KCl, a Sr standard solution, and a Cs standard solution.
(117) Na: 870 ppm by weight (derived from NaCl)
(118) Mg: 118 ppm by weight
(119) Ca: 41 ppm by weight
(120) Na: 126 ppm by weight (derived from Na.sub.2SO.sub.4)
(121) K: 32 ppm by weight
(122) Cs: 1 ppm by weight
(123) Sr: 1 ppm by weight
(124) (Herein, the total concentration of Na was 996 ppm by weight)
(125) To 1 L of the simulated seawater, 0.05 g of the silicotitanate composition of this example was added, and the simulated seawater was stirred at 25° C. and 800 rpm for 24 hours. The Sr and Cs adsorption properties of the silicotitanate composition were evaluated. As a pre-treatment, the silicotitanate composition was heated at 100° C. in the air for 1 hour.
(126) After the evaluation of the adsorption properties, the Sr concentration in the simulated seawater was 0.86 ppm by weight, and the Cs concentration was 0.021 ppm by weight. Kd of each metal was as follows.
(127) Kd.sub.(Cs): 932,000 mL/g
(128) Kd.sub.(Sr): 3,260 mL/g
(129) The removal ratio of each metal was as follows.
(130) Cs: 98.9%
(131) Sr: 14%
(132) Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 6.
(133) TABLE-US-00006 TABLE 6 Si/Ti M/Ti Cs REMOVAL Sr REMOVAL MOLE RATIO MOLE RATIO Kd.sub.(Cs) RATIO [%] Kd.sub.(Sr) RATIO [%] EXAMPLE 1 0.68 1.07 NOT MEASURED NOT MEASURED NOT MEASURED NOT MEASURED EXAMPLE 2 0.75 1.31 230,000 92.0 18,000 48 EXAMPLE 3 0.72 1.25 NOT MEASURED NOT MEASURED NOT MEASURED NOT MEASURED EXAMPLE 4 0.67 1.04 932,000 98.9 3,260 14
Comparative Example 1
(134) 9 g of tetraethyl orthosilicate and 10 g of tetraisopropyl orthotitanate were mixed, and the mixture was mixed in a mixed solution of 9 g of a sodium hydroxide solution (NaOH; 48% by weight) and 49 g of water to obtain a raw material mixture having the following composition.
(135) Si/Ti mole ratio=1.30
(136) Na/Ti mole ratio=3.3
(137) H.sub.2O/Ti mole ratio=82
(138) The obtained raw material composition was a silicotitanate gel. The silicotitanate gel included 6.6% by weight of ethyl alcohol and 7.5% by weight of isopropyl alcohol as byproducts. Since a large amount of alcohol was included, crystallization was not achieved by heating at 180° C. using the same autoclave as in Examples.
Comparative Example 2
(139) A raw material mixture and a crystallized product were obtained in the same manner as in Example 1 except that titanium oxide (anatase type TiO.sub.2 powder) was used instead of a titanium sulfate aqueous solution. The resulting crystallized product was cooled, filtered, washed, and dried to obtain a powder product.
(140) From an XRD chart of the obtained powder product, a peak attributable to titanium oxide was confirmed, but a peak attributable to a sitinakite structure was not confirmed. The XRD chart of the product of this comparative example is shown in
(141) From the XRD chart of the raw material mixture of this comparative example, an XRD peak of titanium oxide (anatase type TiO.sub.2 powder) and an XRD peak of crystalline titanium oxide were confirmed. The raw material mixture of this comparative example was confirmed to be a mixture of crystalline titanium oxide but not to be a silicotitanate gel.
Example 5
(142) 20 g of sodium silicate (SiO.sub.2; 29.1% by weight), 46 g of an aqueous solution of titanium sulfate (TiO.sub.2; 13.31% by weight), 50 g of sodium hydroxide (NaOH; 48% by weight), and 77 g of pure water were mixed to obtain an amorphous silicotitanate gel of the following composition.
(143) Si/Ti mole ratio=1.31
(144) Na/Ti mole ratio=3.3
(145) H.sub.2O/Ti mole ratio=82
(146) To the obtained amorphous silicotitanate gel, 0.73 g of niobium oxide (Nb.sub.2O.sub.5) powder was added, to obtain a raw material mixture including an amorphous silicotitanate gel of the following composition.
(147) Si/Ti mole ratio=1.31
(148) Na/Ti mole ratio=3.3
(149) H.sub.2O/Ti mole ratio=82
(150) Nb/Ti mole ratio=0.2
(151) A crystallized product was obtained by crystallizing the raw material mixture in the same manner as in Example 1 except that the aforementioned raw material mixture was used. The pressure during crystallization was 0.8 MPa. The crystallized product was cooled, filtered, washed, and dried in the same manner as in Example 1 to obtain a niobium-containing silicotitanate composition in a powder form.
(152) From an XRD chart of the obtained niobium-containing silicotitanate composition, an XRD peak attributable to a component other than a sitinakite structure was not confirmed. The silicotitanate composition of this example was confirmed to be a single phase of S-type silicotitanate. The XRD chart of the silicotitanate composition of this example is shown in
(153) The Si/Ti mole ratio of the obtained niobium-containing silicotitanate composition was 0.67, the Na/Ti mole ratio was 1.35, and the Nb/Ti mole ratio was 0.16. Results of composition analysis of the obtained silicotitanate composition are shown in Table 9.
(154)
(155)
(156) (Evaluation of Sr Adsorption Properties)
(157) The Sr selective adsorption properties were evaluated in the same manner as in Example 2. After the evaluation of the adsorption properties, the Sr concentration in the measurement solution was 0.50 ppm by weight, the calcium concentration that was a seawater component was 39.5 ppm by weight, and the magnesium concentration was 115 ppm by weight. Kd of each metal determined by the above-described equation (1) was as follows.
(158) Kd.sub.(Sr): 20,000 mL/g
(159) Kd.sub.(Ca): 7,600 mL/g
(160) Kd.sub.(Mg): 5,200 mL/g
(161) The removal ratio of each metal determined by the above-described equation (2) was as follows.
(162) Sr: 50%
(163) Ca: 3.6%
(164) Mg: 2.5%
(165) Therefore, Kd.sub.(Sr) was 10,000 mL/g or more, and was larger than Kd of calcium and magnesium. The Sr removal ratio was larger than calcium and magnesium removal ratios. The silicotitanate composition of this example was confirmed to have Sr adsorption selectivity in the coexistence of seawater component.
(166) As compared with Example 2 in which Nb was not contained, the Sr removal ratio was larger. The silicotitanate composition was confirmed to have excellent Sr adsorption selectivity in the coexistence of seawater component.
(167) (Evaluation of Cesium Adsorption Properties)
(168) For the obtained silicotitanate composition, the Cs selective adsorption properties from simulated seawater were evaluated in the same manner as in Example 2.
(169) After the evaluation of the adsorption properties, the Cs concentration in the measurement solution was 0.011 ppm by weight. By the above-described equation (1), Kd.sub.(Cs) was 1, 800,000 mL/g. The Cs removal ratio was 98.9%. Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 9.
(170) Kd.sub.(Cs) was very large as described above, and the removal ratio was also larger.
(171) As compared with Example 2 in which Nb was not contained, the Sr and Cs removal ratios in the coexistence of seawater component in Example 4 were larger. A performance effect of a niobium additive was confirmed.
Example 6
(172) 20 g of sodium silicate (SiO.sub.2; 29.1% by weight), 72 g of titanium oxysulfate (TiO.sub.2; 16.3% by weight), 50 g of sodium hydroxide (NaOH; 48% by weight), and 77 g of pure water were mixed to obtain an amorphous silicotitanate gel of the following composition.
(173) Si/Ti mole ratio=1.34
(174) Na/Ti mole ratio=3.3
(175) H.sub.2O/Ti mole ratio=82
(176) To the obtained amorphous silicotitanate gel, 0.98 g of niobium hydroxide (Nb(OH).sub.5) powder was added to obtain a raw material mixture including an amorphous silicotitanate gel of the following composition.
(177) Si/Ti mole ratio=1.34
(178) Na/Ti mole ratio=3.3
(179) H.sub.2O/Ti mole ratio=82
(180) Nb/Ti mole ratio=0.35
(181) A crystallized product was obtained by crystallizing the raw material mixture in the same manner as in Example 1 except that the aforementioned raw material mixture was used. The crystallized product was cooled, filtered, washed, and dried in the same manner as in Example 1 to obtain a niobium-containing silicotitanate composition in a powder form.
(182) From an XRD chart of the obtained niobium-containing silicotitanate composition, an XRD peak attributable to a component other than a sitinakite structure was not confirmed. The silicotitanate composition of this example was confirmed to be a single phase of S-type silicotitanate. The XRD chart of the silicotitanate composition of this example is shown in
(183) The Si/Ti mole ratio of the obtained niobium-containing silicotitanate composition was 0.73, the Na/Ti mole ratio was 1.35, and the Nb/Ti mole ratio was 0.33. Results of composition analysis of the obtained silicotitanate composition are shown in Table 9.
(184) (Evaluation of Sr and Cs Adsorption Properties)
(185) For the obtained silicotitanate composition, the Sr and Cs selective adsorption properties from simulated seawater were evaluated. Simulated seawater having the following composition was prepared using NaCl, MgCl.sub.2, CaCl.sub.2, a Sr standard solution, and a Cs standard solution.
(186) Na: 996 ppm by weight
(187) Mg: 118 ppm by weight
(188) Ca: 41 ppm by weight
(189) Sr: 1 ppm by weight
(190) Cs: 1 ppm by weight
(191) To 1 L of the simulated seawater, 0.05 g of the silicotitanate composition was added, and the mixture was mixed with stirring at 25° C. and 800 rpm for 24 hours. Thus, the adsorption properties were evaluated.
(192) After the evaluation of the adsorption properties, the Sr concentration in the simulated seawater was 0.63 ppm by weight, the Cs concentration was 0.008 ppm, the calcium concentration was 39.5 ppm by weight, and the magnesium concentration was 115 ppm by weight. Kd of each metal determined by the above-described equation (1) was as follows.
(193) Kd.sub.(Sr): 12,000 mL/g
(194) Kd.sub.(Cs): 2,400,000 mL/g
(195) Kd.sub.(Ca): 5,000 mL/g
(196) Kd.sub.(Mg): 5,200 mL/g
(197) The removal ratio of each metal determined by the above-described equation (2) was as follows.
(198) Sr: 37%
(199) Cs: 99.2%
(200) Ca: 3.7%
(201) Mg: 2.5%
(202) Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 9.
(203) Therefore, Kd.sub.(Sr) was 10,000 mL/g or more, Kd.sub.(Cs) was 100,000 mL/g or more, and they were larger than Kd of calcium and magnesium. The Sr and Cs removal ratios were larger than calcium and magnesium removal ratios. The silicotitanate composition of this example was confirmed to have Sr and Cs adsorption selectivities in the coexistence of seawater component.
(204) As compared with Example 2 in which the composition of simulated seawater was different but Nb was not contained, the Sr and Cs removal ratios were larger. The silicotitanate composition was confirmed to have excellent Sr and Cs adsorption selectivities in the coexistence of seawater component.
Example 7
(205) An amorphous silicotitanate gel was obtained in the same manner as in Example 4 except that the amorphous silicotitanate gel had the following composition.
(206) Si/Ti mole ratio=1.34
(207) Na/Ti mole ratio=3.3
(208) Nb/Ti mole ratio=0.2
(209) H.sub.2O/Ti mole ratio=82
(210) The amorphous silicotitanate gel was crystallized in the same manner as in Example 1, and the crystallized product was further cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(211) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 7, and was confirmed to be a single phase of S-type silicotitanate composition. The XRD pattern is shown in
(212) TABLE-US-00007 TABLE 7 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 11.3 100 27.4 40
(213) The Sr and Cs selective adsorption properties were evaluated in the same manner as in Example 4. After the evaluation of the adsorption properties, the Sr concentration in the simulated seawater was 0.85 ppm by weight, and the Cs concentration was 0.007 ppm by weight. Kd of each metal was as follows.
(214) Kd.sub.(Cs): 2,840,000 mL/g
(215) Kd.sub.(Sr): 3,530 mL/g
(216) The removal ratio of each metal was as follows.
(217) Cs: 99.3%
(218) Sr: 15%
(219) Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 9.
Example 8
(220) An amorphous silicotitanate gel was obtained in the same manner as in Example 4 except that the amorphous silicotitanate gel had the following composition.
(221) Si/Ti mole ratio=1.34
(222) Na/Ti mole ratio=3.3
(223) Nb/Ti mole ratio=0.35
(224) H.sub.2O/Ti mole ratio=82
(225) The amorphous silicotitanate gel was crystallized in the same manner as in Example 1, and the crystallized product was further cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(226) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 8, and was confirmed to be a single phase of S-type silicotitanate composition. The XRD pattern is shown in
(227) TABLE-US-00008 TABLE 8 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 11.3 100 27.5 38
(228) The Sr and Cs selective adsorption properties were evaluated in the same manner as in Example 1. After the evaluation of the adsorption properties, the Sr concentration in the simulated seawater was 0.73 ppm by weight, and the Cs concentration was 0.008 ppm by weight. Kd of each metal was as follows.
(229) Kd.sub.(Cs): 2,480,000 mL/g
(230) Kd.sub.(Sr): 7,400 mL/g
(231) The removal ratio of each metal was as follows.
(232) Cs: 99.2%
(233) Sr: 27%
(234) Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 9.
Comparative Example 3
(235) 9 g of tetraethyl orthosilicate and 10 g of tetraisopropyl orthotitanate were mixed, and the mixture was mixed in a mixed solution of 9 g of a sodium hydroxide solution (NaOH; 48% by weight) and 49 g of water to obtain a raw material mixture having the following composition.
(236) Si/Ti mole ratio=1.18
(237) Na/Ti mole ratio=0.3.8
(238) H.sub.2O/Ti mole ratio=82
(239) The obtained raw material mixture was a silicotitanate gel. The silicotitanate gel included 6.5% by weight of ethyl alcohol and 7.6% by weight of isopropyl alcohol as byproducts. For a removal treatment of alcohols as byproducts, a nitrogen gas was blown into the silicotitanate gel from an upper portion of an autoclave. After 12 hours, to the obtained amorphous silicotitanate gel, 0.73 g of niobium oxide (Nb.sub.2O.sub.5) powder was added, to obtain a raw material mixture including an amorphous silicotitanate gel of the following composition.
(240) Si/Ti mole ratio=1.18
(241) Na/Ti mole ratio=3.8
(242) H.sub.2O/Ti mole ratio=82
(243) Nb/Ti mole ratio=0.2
(244) A crystallized product was obtained by crystallizing the raw material mixture in the same manner as in Example 1 except that the aforementioned raw material mixture was used. The pressure during crystallization was 0.8 MPa. The crystallized product was cooled, filtered, washed, and dried in the same manner as in Example 1 to obtain a niobium-containing silicotitanate composition in a powder form.
(245) From an XRD chart of the obtained niobium-containing silicotitanate composition, an XRD peak attributable to a component other than a sitinakite structure was not confirmed. Therefore, the silicotitanate composition of this comparative example was confirmed to be a single phase of S-type silicotitanate. The XRD chart of the silicotitanate composition of this comparative example is shown in
(246) The Si/Ti mole ratio of the obtained niobium-containing silicotitanate composition was 0.66, the Na/Ti mole ratio was 1.23, and the Nb/Ti mole ratio was 0.17. Results of composition analysis of the obtained silicotitanate composition are shown in Table 9.
(247)
(248) (Evaluation of Sr Adsorption Properties)
(249) For the obtained silicotitanate composition, the Sr and Cs selective adsorption properties from simulated seawater were evaluated. Simulated seawater having the following composition was prepared using NaCl, MgCl.sub.2, CaCl.sub.2, a Sr standard solution, and a Cs standard solution.
(250) Na: 996 ppm by weight
(251) Mg: 118 ppm by weight
(252) Ca: 41 ppm by weight
(253) Sr: 1 ppm by weight
(254) Cs: 1 ppm by weight
(255) To 1 L of the simulated seawater, 0.05 g of the silicotitanate composition was added, and the mixture was mixed with stirring at 25° C. and 800 rpm for 24 hours. Thus, the adsorption properties were evaluated.
(256) After the evaluation of the adsorption properties, the Sr concentration in the simulated seawater was 0.85 ppm by weight, the Cs concentration was 0.34 ppm, the calcium concentration that was a seawater component was 38.0 ppm by weight, and the magnesium concentration was 110 ppm by weight. Kd of each metal determined by the above-described equation (1) was as follows.
(257) Kd.sub.(Sr): 3,500 mL/g
(258) Kd.sub.(Cs): 39,000 mL/g
(259) Kd.sub.(Ca): 1,600 mL/g
(260) Kd.sub.(Mg): 1,500 mL/g
(261) The removal ratio of each metal determined by the above-described equation (2) was as follows.
(262) Sr: 15%
(263) Cs: 66%
(264) Ca: 7.3%
(265) Mg: 6.8%
(266) Results of Cs and Sr adsorptivities of the silicotitanate composition of this comparative example are shown in Table 9.
(267) Kd.sub.(Sr) was less than 10,000 mL/g, and Kd.sub.(Cs) was less than 100,000 mL/g. The silicotitanate composition of this comparative example was confirmed to have inferior Sr and Cs adsorption selectivities in the coexistence of seawater component.
(268) As compared with Example 5 in which the composition of simulated seawater was different but Nb was contained, Kd.sub.(Sr) and Kd.sub.(Cs) were lower. This shows that the Sr and Cs adsorption selectivities in the coexistence of seawater component are inferior.
(269) TABLE-US-00009 TABLE 9 Si/Ti M/Ti Nb/Ti Cs REMOVAL Sr REMOVAL MOLE RATIO MOLE RATIO MOLE RATIO Kd.sub.(Cs) RATIO [%] Kd.sub.(Sr) RATIO [%] EXAMPLE 5 0.67 1.35 0.16 1,800,000 98.9 20,000 50 EXAMPLE 6 0.73 1.35 0.33 2,400,000 99.2 12,000 37 EXAMPLE 7 0.69 1.17 0.19 2,840,000 99.3 3,530 15 EXAMPLE 8 0.73 1.35 0.33 2,480,000 99.2 7,400 27 COMPARATIVE 0.66 1.23 0.17 39,000 66.0 3,500 15 EXAMPLE 3
Example 9
(270) 20 g of sodium silicate (SiO.sub.2; 29.1% by weight), 71 g of an aqueous solution of titanium oxysulfate (TiOSO.sub.4; 8.2% by weight), 63 g of sodium hydroxide (NaOH; 48% by weight), and 41 g of pure water were mixed to obtain an amorphous silicotitanate gel of the following composition.
(271) Si/Ti mole ratio=1.37
(272) Na/Ti mole ratio=3.3
(273) H.sub.2O/Ti mole ratio=82
(274) To the obtained amorphous silicotitanate gel, 8.0 g of niobium hydroxide (Nb(OH).sub.5) powder and a silicotitanate having a crystal of sitinakite structure as a seed crystal in an amount of 1% by weight relative to the amorphous silicotitanate gel were added. Subsequently, an amorphous silicotitanate gel including an amorphous silicotitanate gel of the following composition was obtained.
(275) Si/Ti mole ratio=1.37
(276) Na/Ti mole ratio=3.3
(277) Nb/Ti mole ratio=0.4
(278) H.sub.2O/Ti mole ratio=82
(279) The amorphous silicotitanate gel was charged in a stainless steel autoclave (trade name: KH-02, manufactured by HIRO COMPANY) with stirring. The amorphous silicotitanate gel was crystallized by heating at 180° C. for 72 hours, to obtain a crystallized product.
(280) The pressure during crystallization was 0.8 MPa, which corresponded to a water vapor pressure at 180° C. The crystallized product was cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(281) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 10. The XRD pattern is shown in
(282) TABLE-US-00010 TABLE 10 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 11.3 100 27.7 57 29.4 54
(283) The Cs and Sr selective adsorption properties were evaluated in the same manner as in Example 4. After the evaluation of the adsorption properties, the Cs concentration in the simulated seawater was 0.020 ppm by weight, and the Sr concentration was 0.40 ppm by weight. Kd of each metal was as follows.
(284) Kd.sub.(Cs): 980,000 mL/g
(285) Kd.sub.(Sr): 30,000 mL/g
(286) The removal ratio of each metal was as follows.
(287) Cs: 98.0%
(288) Sr: 60%
(289) Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 13.
Example 10
(290) An amorphous silicotitanate gel was prepared in the same manner as in Example 9 except that the amorphous silicotitanate gel had the following composition:
(291) Si/Ti mole ratio=1.37
(292) Na/Ti mole ratio=3.3
(293) Nb/Ti mole ratio=0.5
(294) H.sub.2O/Ti mole ratio=82
(295) The amorphous silicotitanate gel was crystallized in the same manner as in Example 1, and the crystallized product was further cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(296) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 11. The XRD pattern is shown in
(297) TABLE-US-00011 TABLE 11 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 11.3 100 27.8 56 29.5 57
(298) The Sr and Cs selective adsorption properties were evaluated in the same manner as in Example 4. After the evaluation of the adsorption properties, the Cs concentration in the simulated seawater was 0.032 ppm by weight, and the Sr concentration was 0.35 ppm by weight. Kd of each metal was as follows.
(299) Kd.sub.(Cs): 605,000 mL/g
(300) Kd.sub.(Sr): 37,300 mL/g
(301) The removal ratio of each metal was as follows.
(302) Cs: 96.8%
(303) Sr: 65%
(304) Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 13.
Example 11
(305) An amorphous silicotitanate gel was prepared in the same manner as in Example 9 except that the amorphous silicotitanate gel had the following composition.
(306) Si/Ti mole ratio=1.37
(307) Na/Ti mole ratio=3.3
(308) Nb/Ti mole ratio=0.6
(309) H.sub.2O/Ti mole ratio=82
(310) The amorphous silicotitanate gel was crystallized in the same manner as in Example 1, and the crystallized product was further cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(311) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 12. The XRD pattern is shown in
(312) TABLE-US-00012 TABLE 12 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 11.3 100 27.5 47 29.5 36
(313) The Cs and Sr selective adsorption properties were evaluated in the same manner as in Example 4. After the evaluation of the adsorption properties, the Cs concentration in the simulated seawater was 0.012 ppm by weight, and the Sr concentration was 0.54 ppm by weight. Kd of each metal was as follows.
(314) Kd.sub.(Cs): 1,650,000 mL/g
(315) Kd.sub.(Sr): 16,900 mL/g
(316) The removal ratio of each metal was as follows.
(317) Cs: 98.8%
(318) Sr: 56%
(319) Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 13.
(320) TABLE-US-00013 TABLE 13 Si/Ti M/Ti Nb/Ti Cs REMOVAL Sr REMOVAL MOLE RATIO MOLE RATIO MOLE RATIO Kd.sub.(Cs) RATIO [%] Kd.sub.(Sr) RATIO [%] EXAMPLE 9 0.79 1.40 0.37 980,000 98.0 30,000 60 EXAMPLE 10 0.82 1.49 0.46 605,000 96.8 37,300 65 EXAMPLE 11 0.86 1.62 0.56 1,650,000 98.8 16,900 56
Example 12
(321) An amorphous silicotitanate gel was prepared in the same manner as in Example 9 except that the amorphous silicotitanate gel had the following composition.
(322) Si/Ti mole ratio=1.37
(323) Na/Ti mole ratio=3.3
(324) Nb/Ti mole ratio=0.8
(325) H.sub.2O/Ti mole ratio=82
(326) The amorphous silicotitanate gel was charged in a stainless steel autoclave (trade name: KH-02, manufactured by HIRO COMPANY) with stirring. The amorphous silicotitanate gel was crystallized by heating at 180° C. for 72 hours, to obtain a crystallized product.
(327) The pressure during crystallization was 0.8 MPa, which corresponded to a water vapor pressure at 180° C. The crystallized product was cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(328) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 14. The XRD pattern is shown in
(329) TABLE-US-00014 TABLE 14 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 8.8 15 10.0 14 11.3 100 29.7 28
(330) The Cs and Sr selective adsorption properties were evaluated in the same manner as in Example 4. After the evaluation of the adsorption properties, the Cs concentration in the simulated seawater was 0.017 ppm by weight, and the Sr concentration was 0.53 ppm by weight. Kd of each metal was as follows.
(331) Kd.sub.(Cs): 1,160,000 mL/g
(332) Kd.sub.(Sr): 17,700 mL/g
(333) The removal ratio of each metal was as follows.
(334) Cs: 98.3%
(335) Sr: 47%
(336) Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 22.
Example 13
(337) An amorphous silicotitanate gel was prepared in the same manner as in Example 9 except that the amorphous silicotitanate gel had the following composition.
(338) Si/Ti mole ratio=1.37
(339) Na/Ti mole ratio=3.3
(340) Nb/Ti mole ratio=1.0
(341) H.sub.2O/Ti mole ratio=82
(342) The amorphous silicotitanate gel was crystallized in the same manner as in Example 1, and the crystallized product was further cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(343) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 15. The XRD pattern is shown in
(344) TABLE-US-00015 TABLE 15 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 8.8 17 10.0 14 11.3 100 29.7 30
(345) The Cs and Sr selective adsorption properties were evaluated in the same manner as in Example 4. After the evaluation of the adsorption properties, the Cs concentration in the simulated seawater was 0.021 ppm by weight, and the Sr concentration was 0.44 ppm by weight. Kd of each metal was as follows.
(346) Kd.sub.(Cs): 932,000 mL/g
(347) Kd.sub.(Sr): 25,500 mL/g
(348) The removal ratio of each metal was as follows.
(349) Cs: 97.9%
(350) Sr: 56%
(351) Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 22.
Example 14
(352) An amorphous silicotitanate gel was prepared in the same manner as in Example 9 except that the amorphous silicotitanate gel had the following composition.
(353) Si/Ti mole ratio=1.34
(354) Na/Ti mole ratio=3.3
(355) Nb/Ti mole ratio=0.4
(356) H.sub.2O/Ti mole ratio=123
(357) The amorphous silicotitanate gel was crystallized in the same manner as in Example 1, and the crystallized product was further cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(358) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 16. The XRD pattern is shown in
(359) TABLE-US-00016 TABLE 16 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 8.7 9 9.9 8 11.2 100 29.6 10
(360) The Cs and Sr selective adsorption properties were evaluated in the same manner as in Example 4. After the evaluation of the adsorption properties, the Cs concentration in the simulated seawater was 0.0038 ppm by weight, and the Sr concentration was 0.71 ppm by weight. Kd of each metal was as follows.
(361) Kd.sub.(Cs): 5,240,000 mL/g
(362) Kd.sub.(Sr): 8,250 mL/g
(363) The removal ratio of each metal was as follows.
(364) Cs: 99.62%
(365) Sr: 29%
(366) Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 22.
Example 15
(367) An amorphous silicotitanate gel was prepared in the same manner as in Example 9 except that the amorphous silicotitanate gel had the following composition.
(368) Si/Ti mole ratio=1.34
(369) Na/Ti mole ratio=3.3
(370) Nb/Ti mole ratio=0.5
(371) H.sub.2O/Ti mole ratio=114
(372) The amorphous silicotitanate gel was charged in a stainless steel autoclave (trade name: KH-02, manufactured by HIRO COMPANY) with stirring. The amorphous silicotitanate gel was crystallized by heating at 180° C. for 72 hours, to obtain a crystallized product.
(373) The pressure during crystallization was 0.8 MPa, which corresponded to a water vapor pressure at 180° C. The crystallized product was cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(374) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 17. The XRD pattern is shown in
(375) TABLE-US-00017 TABLE 17 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 8.8 10 10.0 10 11.2 100 29.6 14
(376) The Cs and Sr selective adsorption properties were evaluated in the same manner as in Example 4. After the evaluation of the adsorption properties, the Cs concentration in the simulated seawater was 0.0037 ppm by weight, and the Sr concentration was 0.67 ppm by weight. Kd of each metal was as follows.
(377) Kd.sub.(Cs): 5,390,000 mL/g
(378) Kd.sub.(Sr): 10,100 mL/g
(379) The removal ratio of each metal was as follows.
(380) Cs: 99.63%
(381) Sr: 33%
(382) Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 22.
Example 16
(383) An amorphous silicotitanate gel was prepared in the same manner as in Example 9 except that the amorphous silicotitanate gel had the following composition.
(384) Si/Ti mole ratio=1.34
(385) Na/Ti mole ratio=3.3
(386) Nb/Ti mole ratio=0.6
(387) H.sub.2O/Ti mole ratio=123
(388) The amorphous silicotitanate gel was crystallized in the same manner as in Example 1, and the crystallized product was further cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(389) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 18. The XRD pattern is shown in
(390) TABLE-US-00018 TABLE 18 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 8.8 14 10.0 11 11.2 100 29.6 20
(391) The Cs and Sr selective adsorption properties were evaluated in the same manner as in Example 4. After the evaluation of the absorption properties, the Cs concentration in the simulated seawater was 0.0044 ppm by weight, and the Sr concentration was 0.64 ppm by weight. Kd of each metal was as follows.
(392) Kd.sub.(Cs): 4,530,000 mL/g
(393) Kd.sub.(Sr): 11,300 mL/g
(394) The removal ratio of each metal was as follows.
(395) Cs: 99.56%
(396) Sr: 36%
(397) Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 22.
Example 17
(398) An amorphous silicotitanate gel was prepared in the same manner as in Example 9 except that the amorphous silicotitanate gel had the following composition.
(399) Si/Ti mole ratio=1.34
(400) Na/Ti mole ratio=3.3
(401) Nb/Ti mole ratio=0.6
(402) H.sub.2O/Ti mole ratio=109
(403) The amorphous silicotitanate gel was crystallized in the same manner as in Example 1, and the crystallized product was further cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(404) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 19. The XRD pattern is shown in
(405) TABLE-US-00019 TABLE 19 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 8.7 11 10.0 10 11.2 100 29.6 18
(406) The Cs and Sr selective adsorption properties were evaluated in the same manner as in Example 4. After the evaluation of the adsorption properties, the Cs concentration in the simulated seawater was 0.0029 ppm by weight, and the Sr concentration was 0.62 ppm by weight. Kd of each metal was as follows.
(407) Kd.sub.(Cs): 6,880,000 mL/g
(408) Kd.sub.(Sr): 12,300 mL/g
(409) The removal ratio of each metal was as follows.
(410) Cs: 99.71%
(411) Sr: 38%
(412) Results of Cs and Sr adsorptivities of the silicotitanate composition of this example are shown in Table 22.
Example 18
(413) An amorphous silicotitanate gel was prepared in the same manner as in Example 9 except that the amorphous silicotitanate gel had the following composition.
(414) Si/Ti mole ratio=1.34
(415) Na/Ti mole ratio=3.3
(416) Nb/Ti mole ratio=0.5
(417) H.sub.2O/Ti mole ratio=109
(418) The amorphous silicotitanate gel was crystallized in the same manner as in Example 1 except that the crystallization time was changed to 24 hours, and the crystallized product was further cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(419) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 20. The XRD pattern is shown in
(420) TABLE-US-00020 TABLE 20 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 8.8 9 10.0 8 11.3 100 29.7 11
(421) The Sr selective adsorption properties were evaluated in the same manner as in Example 4. After the evaluation of the adsorption properties, the Sr concentration in the simulated seawater was 0.70 ppm by weight. Kd.sub.(Sr) was as follows.
(422) Kd.sub.(Sr): 9,700 mL/g
(423) The removal ratio of each metal was as follows.
(424) Sr: 30%
(425) Results of Sr adsorptivity of the silicotitanate composition of this example are shown in Table 22.
Example 19
(426) An amorphous silicotitanate gel was prepared in the same manner as in Example 9 except that the amorphous silicotitanate gel had the following composition and a seed crystal was not added to the gel.
(427) Si/Ti mole ratio=1.34
(428) Na/Ti mole ratio=3.3
(429) Nb/Ti mole ratio=0.5
(430) H.sub.2O/Ti mole ratio=109
(431) The amorphous silicotitanate gel was crystallized in the same manner as in Example 1 except that the crystallization time was changed to 24 hours, and the crystallized product was further cooled, filtered, washed, and dried to obtain a silicotitanate composition.
(432) From results of XRD measurement, the obtained silicotitanate composition was confirmed to have an X-ray diffraction angle and a diffraction peak intensity ratio shown in Table 21. The XRD pattern is shown in
(433) TABLE-US-00021 TABLE 21 DIFFRACTION ANGLE 2θ [°] XRD PEAK INTENSITY RATIO 8.8 10 10.0 10 11.2 100 29.6 15
(434) The Sr selective adsorption properties were evaluated in the same manner as in Example 4. After the evaluation of the adsorption properties, the Sr concentration in the simulated seawater was 0.67 ppm by weight. Kd.sub.(Sr) was as follows.
(435) Kd.sub.(Sr): 9,850 mL/g
(436) The Sr removal ratio was as follows.
(437) Sr: 33%
(438) Results of Sr adsorptivity of the silicotitanate composition of this example are shown in Table 22.
(439) TABLE-US-00022 TABLE 22 Si/Ti M/Ti Nb/Ti Cs REMOVAL Sr REMOVAL MOLE RATIO MOLE RATIO MOLE RATIO Kd.sub.(Cs) RATIO [%] Kd.sub.(Sr) RATIO [%] EXAMPLE 12 0.98 1.86 0.75 1,160,000 98.3 17,700 47 EXAMPLE 13 1.50 2.06 1.05 932,000 97.9 25,500 56 EXAMPLE 14 0.70 1.19 0.39 5,240,000 99.62 8,250 29 EXAMPLE 15 0.74 1.38 0.48 5,390,000 99.63 10,100 33 EXAMPLE 16 0.75 1.33 0.56 4,530,000 99.56 11,300 36 EXAMPLE 17 0.74 1.27 0.57 6,880,000 99.71 12,300 38 EXAMPLE 18 0.70 1.19 0.48 NOT MEASURED NOT MEASURED 9,700 30 EXAMPLE 19 0.96 1.65 0.46 NOT MEASURED NOT MEASURED 9,850 33
(440) The present invention has been described in detail with reference to specific embodiments. It will be apparent to one skilled in the art that various changes and modifications can be made thereto without departing from the spirit and scope of the present invention.
(441) The entire disclosures of JP2014-147677 filed on Jul. 18, 2014, JP2015-039326 filed on Feb. 27, 2015, JP2015-096690 filed on May 11, 2015, and JP2015-096691 filed on May 11, 2015 including specifications, claims, drawings, and abstracts are incorporated herein in its entirety by reference.
INDUSTRIAL APPLICABILITY
(442) The present invention provides a production method for a composition including a silicotitanate having a sitinakite structure that can achieve safety production using an inexpensive raw material and can use a general-purpose autoclave. The obtained silicotitanate composition allows harmful ions such as Cs and Sr in the coexistent of seawater, groundwater, and contaminated water to be efficiently treated.