Ion sieve for adsorbing cesium ions and method for preparing the same

Abstract

The application belongs to the technical field of ion sieve, and discloses an ion sieve for adsorbing cesium ions and a preparation method thereof. 13 Then, the ion sieve for adsorbing cesium is obtained by immersing in an acid solution. The cesium ion sieve prepared by the high-temperature solid-phase method has good ion exchange selectivity for Cs+, high saturated exchange capacity, high crystallinity, pure product and good crystallization effect.

Description

TECHNICAL FIELD

[0001] The present application relates to ion sieve, in particular to a kind of ion sieve for adsorbing cesium ion and preparation method thereof. BACKGROUND

[0002] Cesium and its compounds are widely used in optical crystal, medicine, catalyst, nuclear energy, information industry, aerospace industry, fluorescent material, electronic technology and automation and other high-tech fields, also used in cesium atomic clock, photocell, and demand is steadily increasing.Cesium is a scarce resource, the average content of cesium in the earth's crust is 3.0 mg / L, seawater also contains cesium (content about 3.0 × 10-4 mg / L, total amount is large, concentration is low).In many salt lake brine in China contains cesium resources, mainly distributed in Qinghai, Tibet, Hubei and other places, in Zhabuye Salt Lake and other salt lake brine, geothermal water, hot spring in Qinghai-Tibet Plateau contains Cs + , in the lithium extraction mother liquor often also contains Cs + . Zhabuye Salt Lake, Cunmucuo Salt Lake and other Cs + content is 12.15-34.5 mg / L, has exploitation value. Nuclear reaction waste liquid contains a large amount of radioactive Cs137, which needs to be extracted and recovered.

[0003] From the seawater, nuclear waste liquid, salt lake brine and geothermal water and other low cesium content solutions, there are precipitation method, extraction method and ion exchange method (including inorganic ion exchange method and organic ion exchange method) etc., due to the low content of cesium, ion exchange method is a suitable method, among them, the selective inorganic ion exchange method is the preferred method for extracting Cs + from the above seawater, nuclear waste liquid and other dilute solutions, and the inorganic ion exchange method has the characteristics of environmental friendly. There are many studies on the use of inorganic ion exchange method to extract cesium, Xu Shiping, Yu Bo, Xie Jiali, You Xin-feng, Lehto, Wang Rongshu et al. use phosphomolybdate, titanium potassium ferrocyanide, nickel potassium ferrocyanide, sodium silicotitanate and other materials to adsorb and separate Cs + , and determine the ion exchange performance, the highest exchange capacity is 1.74 mmol Cs + / g sodium silicotitanate, Gao Shiyang et al. carried out the study of extracting potassium, rubidium and cesium with clinoptilolite, Huang Wenyan et al. prepared tin phosphate which is selective to cesium, Xiong Liangping, Lv Kai et al. prepared zirconium pyromorphophosphate and W-doped zirconium pyromorphophosphate, and the maximum exchange capacity is 1.66 mmol Cs + / g.

[0004] The controllable preparation of titanium-containing oxide mesoporous materials Cs2xTiyO(2x+y) has not yet attracted much attention. Existing controllable preparation methods for Cs2xTiyO(2x+y) involve cumbersome steps. For example, the sol-gel method is relatively slow, has a long experimental cycle, and requires surfactants, aging steps, and eluents. Another example is the high-temperature solid-phase method, which produces Cs2xTiyO(2x+y) mesoporous materials with complex compositions and poor stability, making it unsuitable for further exploration of cesium saturation adsorption capacity and unable to achieve selective separation of cesium ions. During the experiment, the inventors unexpectedly discovered that by using a suitable titanium source, a method for preparing an ion sieve for adsorbing cesium ions can be provided, which can successfully synthesize a single ion sieve. This ion sieve is expected to achieve new progress and breakthroughs in the three key indicators of saturation exchange capacity, selectivity, and stability. Summary of the Invention

[0005] To address the technical problems of cumbersome preparation methods, poor saturation exchange capacity, selectivity, and stability of existing cesium ion sieves, this invention provides a method for preparing an ion sieve that adsorbs cesium ions.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for preparing an ion sieve for adsorbing cesium ions includes the following steps:

[0008] S1. The titanium hydroxide is used as a titanium source, and is mixed and ground with cesium salt to obtain a cesium titanium composite.

[0009] S2. The cesium titanium composite is calcined to obtain the ion sieve precursor Cs2Ti6O. 13 ;

[0010] S3, the ion sieve precursor Cs2Ti6O 13 The ions are impregnated in an acid solution to obtain an ion sieve that adsorbs cesium.

[0011] The titanium hydroxide can be prepared using conventional methods. Preferably, the preparation method of the titanium hydroxide of the present invention is as follows: [The method involves] mixing Ti4... + NH4 + A titanium sulfate solution and ammonia were prepared in a molar ratio of 1:4. After the heating reaction was completed, the titanium hydroxide precipitate was filtered, washed, and dried to obtain pure titanium hydroxide.

[0012] Preferably, the molar ratio of titanium hydroxide to cesium carbonate is 3:2.

[0013] The preparation method of the ion sieve for adsorbing cesium ions provided by the application is as follows: the initial temperature of roasting is 20 DEG C, the temperature is raised to 100 DEG C at a temperature raising speed of 8 DEG C / min, then the temperature is raised to 400 DEG C at a temperature raising speed of 3 DEG C / min from 100 min, the temperature is kept at 400 DEG C for 120 min, finally the temperature raising speed is changed, the temperature is raised to 800 DEG C in 180 min, and the temperature is kept at 800 DEG C for 4 h.

[0014] Preferably, the roasting is carried out in a tube furnace which can be programmed to raise the temperature.

[0015] The acid solution can be selected from the acid solutions commonly used in the art, and preferably, the acid solution is a hydrochloric acid solution with a molar concentration of 0.2 mol / L; the acid solution can be placed in a constant temperature water bath oscillator for immersion for one week, and the ion sieve precursor after acid modification is filtered, washed and dried to obtain the ion sieve for adsorbing cesium.

[0016] Another object of the application is to provide the ion sieve for adsorbing cesium ions prepared by the above preparation method.

[0017] Finally, the application provides the application of the cesium ion sieve in the selective adsorption of cesium ions in seawater, nuclear waste liquid, salt lake brine and geothermal water.

[0018] The application provides an ion sieve for adsorbing cesium ions and a preparation method thereof. 13 The ion sieve precursor is immersed in an acid solution to obtain the ion sieve for adsorbing cesium. The ion sieve with stable crystal structure, high selectivity for cesium and good stability can be prepared by the high-temperature solid-phase method, the ion sieve can preferentially adsorb Cs+, the ion sieve has good ion exchange selectivity for Cs+, the ion sieve has high saturated exchange capacity for Cs+, and the titanium hydroxide is selected as the titanium source, Cs+ and Ti4+ are completely combined together, the reaction degree is good, the crystallinity is high, the product is pure, and the crystallization effect is good. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The SEM image of the cesium-containing ion sieve precursor Cs2Ti6O 13 provided by the application is shown in the figure;

[0020] Figure 2 The TEM image of the cesium-containing ion sieve precursor Cs2Ti6O 13 provided by the application is shown in the figure;

[0021] Figure 3 The XRD spectrum of the ion sieve precursor Cs2Ti6O 13 provided by Example 1 of the application is shown in the figure;

[0022] Figure 4 XRD pattern of the ion sieve precursor provided for Comparative Example 1;

[0023] Figure 5 XRD pattern of the ion sieve precursor provided for Comparative Example 2. DETAILED DESCRIPTION

[0024] The present application discloses a kind of ion sieve for adsorbing cesium ion and its preparation method, and those skilled in the art can learn from the content herein, and realize by improving process parameters appropriately.The particular need to point out is, all similar replacement and change are obvious to those skilled in the art, and they are all regarded as including in the present application.The method and application of the present application have been described by preferred embodiment, and relevant personnel can obviously make change or appropriate change and combination to the method and application described herein without departing from the content, spirit and scope of the present application, to realize and apply the present application technology.

[0025] In order for those skilled in the art to better understand the present application, the present application will be further described in detail below in conjunction with specific embodiments.

[0026] Example 1

[0027] S1, the titanium hydroxide and cesium carbonate described above are mixed in a molar ratio of 3:2, and are ground thoroughly to obtain a cesium-titanium composite;

[0028] S2, the ground composite is placed in a tube furnace capable of programmed temperature rising for high-temperature calcination; the initial temperature is 20℃, and the temperature rising speed is 8℃ / min, after 10min, the temperature is raised to 100℃; then the temperature rising speed is changed to 3℃ / min, and the temperature is raised to 400℃ after 100min, and stays at 400℃ for 120min; then the temperature rising speed is changed, and the temperature reaches 800℃ after 180min, and stays at 800℃ for 4h, to obtain an ion sieve precursor Cs2Ti6O 13 ;

[0029] S3, the cesium-containing ion sieve precursor Cs2Ti6O 13 obtained in step S2 is added into a 0.2mol / L hydrochloric acid solution, and is placed in a constant-temperature water bath shaker for immersion for one week, the ion sieve precursor after acid modification is filtered, washed, and dried to obtain an ion sieve capable of highly selective adsorption of cesium.

[0030] S2, the cesium-containing ion sieve precursor Cs2Ti6O 13 is subjected to scanning electron microscopy (SEM) test, and the SEM image is shown in Figure 1 , Figure 1 , Figure 1 (a) SEM image with magnification of 10000 times,Figure 1 (b) SEM image with magnification of 20000 times, the cesium ion sieve presents a scale-like structure under the magnification of 20000 times, and is uniformly distributed, the layered structure is beneficial to increase the solid-liquid contact area and improve the adsorption performance of the ion sieve.

[0031] The cesium-containing ion sieve precursor Cs2Ti6O 13 TEM test was performed, and a TEM image is shown in Figure 2 , Figure 2 (a) TEM image with magnification of 40000 times, Figure 2 (b) TEM image with magnification of 6000 times, Figure 2 It can be shown that the ion sieve precursor prepared by the high-temperature solid-phase method provided by the application has a scale-like structure and is uniformly distributed, which is basically consistent with the scanning electron microscope image, and the structure is stable.

[0032] 1 part of 0.1000 g of the cesium ion sieve after acid modification obtained in step S3 was weighed, and 50 ml of a mixed solution (pH=10) of Na + , K + , Cs + , Li + , Mg 2+ , Ca 2+ with a concentration of 0.100 mol / L was added, respectively, and was oscillated at 25℃ for one week, the ion concentration in the supernatant was measured, the ion exchange capacity of the ion sieve for each ion was calculated, and the ion exchange selectivity of the ion sieve was analyzed, which is shown in Table 1.

[0033] Table 1 Ion exchange capacity

[0034]

[0035] As can be seen from the table, in the solutions with the same concentration of Cs + , K + , Na + , Li + , Mg 2+ , Ca 2+ , the ion sieve provided by the application has an ion exchange capacity of 321.39 mg / g for Cs + , the ion sieve preferentially adsorbs Cs + , and the ion sieve has good ion exchange selectivity for Cs + .

[0036] Accurately take 0.1000 g of the acid-modified cesium ion sieve obtained in S3, and place it in a 0.100 mol / L Cs+ solution (pH = 10) for constant temperature oscillation immersion at 25°C. After one week, the ion concentration in the supernatant is measured, and the saturation exchange capacity of cesium ions is calculated according to the reduction amount of cesium ions. The final measured saturation exchange capacity of cesium ions is 471.59 mg / g. The calculation formula is as follows:

[0037]

[0038] Q: saturation exchange capacity, mg / g

[0039] C0: the content of Cs+ in the initial solution, mg / L

[0040] C: the content of Cs+ in the exchange solution, mg / L

[0041] V: the volume of the solution, L

[0042] W: the amount of the exchanger, g.

[0043] It is measured that the saturation exchange capacity of the cesium ions obtained in the application is 471.59 mg / g, accounting for 88.22% of the theoretical value 534.59 mg / g (the theoretical value of the saturation exchange capacity of cesium ions). The data shows that the cesium ions provided by the application have a relatively high saturation exchange capacity.

[0044] The ion sieve precursor Cs2Ti6O 13 is obtained in S2. The XRD pattern of the ion sieve precursor obtained in S2 is shown in Figure 3 , Figure 3 It can be seen that the ion sieve precursor Cs2Ti6O 13 obtained in the application has relatively obvious characteristic peaks, good peak shape, and few impurity peaks. The peak shape and diffraction angle position of the diffraction peak are basically consistent with the data of the standard spectrum PDF38-0170, indicating that the Cs + is completely combined with the Ti 4+ , the reaction degree is good, the crystallinity is high, and the product is ideal.

[0045] Comparative Example 1

[0046] S1, the titanium oxide and cesium carbonate are mixed in a molar ratio of 3:2, and are fully ground to obtain a cesium-titanium composite;

[0047] S2. The ground composite was placed in a tube furnace with programmed temperature rise and calcined at high temperature. The initial temperature was 20℃, and the temperature was increased to 100℃ after 10 min at a heating rate of 8℃ / min. Then, the temperature was increased to 400℃ after 100 min at a heating rate of 3℃ / min, and held at 400℃ for 120 min. Then, the heating rate was changed, and the temperature was increased to 800℃ after 180 min, and held at 800℃ for 4 h to obtain the product ion sieve precursor.

[0048] The ion sieve precursor was subjected to X-ray diffraction analysis, and its XRD pattern is shown in the figure. Figure 4 , Figure 4 The topmost spectrum is the XRD pattern of the ion sieve precursor from the reaction of titanium dioxide and cesium carbonate; spectrum #29-1360 is the XRD pattern of the standard titanium dioxide spectrum; and spectrum #38-170 is the XRD pattern of Cs₂Ti₆O. 13 Standard spectral XRD pattern, Figure 4 The results show that the reaction product of titanium dioxide and cesium carbonate is still mainly titanium dioxide, indicating that titanium dioxide does not react with cesium carbonate. The reason for this may be that titanium dioxide is more stable and does not easily react with other substances. Therefore, titanium dioxide is not selected as the titanium source to prepare ion sieves for adsorbing cesium ions.

[0049] Comparative Example 2

[0050] S1. Mix the above titanium sulfate and cesium carbonate in a molar ratio of 3:2 and grind thoroughly to obtain a cesium titanium complex;

[0051] S2. The ground composite was placed in a tube furnace with programmed temperature rise and calcined at high temperature. The initial temperature was 20℃, and the temperature was increased to 100℃ after 10 min at a heating rate of 8℃ / min. Then, the temperature was increased to 400℃ after 100 min at a heating rate of 3℃ / min, and held at 400℃ for 120 min. Then, the heating rate was changed, and the temperature was increased to 800℃ after 180 min, and held at 800℃ for 4 h to obtain the product ion sieve precursor.

[0052] The above ion sieve precursor was subjected to X-ray diffraction analysis, and its XRD pattern is shown in the figure. Figure 5 , Figure 5 The topmost image is the XRD pattern of the ion sieve precursor obtained from titanium sulfate and cesium carbonate; PDF#38-0170 shows the pattern for Cs₂Ti₆O. 13 Standard spectral XRD pattern, Figure 5 The XRD pattern of the ion sieve precursor produced by the reaction of titanium sulfate and cesium carbonate, after X-ray diffraction, compared with the standard spectrum, shows that the characteristic peaks are not obvious, the peak shapes are poor, and there are many impurity peaks, indicating that the reaction is not complete, the crystallinity is not high, and the product is not ideal. Therefore, titanium sulfate is not selected as the titanium source to prepare ion sieves that adsorb cesium ions.

[0053] The above merely describes the preferred embodiments of the present application, and it should be pointed out that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A method for preparing an ion-sieve for adsorbing cesium ions, characterized by, The method comprises the following steps: S1, titanium hydroxide as a titanium source is mixed with cesium salt and grinded to obtain a cesium-titanium compound; S2, calcining the cesium titanium complex to obtain ion sieve precursor Cs2Ti6O 13 ; S3, the ion-sieve precursor Cs2Ti6O 13 , adding acid solution to impregnate, to obtain cesium-adsorbed ion-sieve.

2. The method for preparing an ion sieve according to claim 1, wherein The cesium salt is cesium carbonate, and the molar ratio of the titanium hydroxide to the cesium carbonate is 3:

2.

3. The method of claim 1, wherein the ion sieve is prepared by the steps of: The initial temperature of the calcination is 20℃, the temperature is raised to 100℃ at a temperature raising speed of 8℃ / min, then the temperature is raised to 400℃ at a temperature raising speed of 3℃ / min for 100 min, the temperature is kept at 400℃ for 120 min, finally the temperature is raised to 800℃ at a changed temperature raising speed for 180 min, and the temperature is kept at 800℃ for 4 h.

4. The method for preparing an ion sieve according to claim 3, wherein The calcination is carried out in a tube furnace capable of programmed temperature raising.

5. The method of claim 1, wherein the ion sieve is prepared by the steps of: The acid solution is a hydrochloric acid solution, and the molar concentration of the hydrochloric acid solution is 0.2 mol / L.

6. The method for preparing an ion sieve according to claim 1 or 5, characterized by, The acid solution is placed in a constant temperature water bath oscillator, and the ion sieve precursor after acid modification is immersed for one week, then filtered, washed and dried to obtain the ion sieve adsorbing cesium.

7. The ion sieve adsorbing cesium ions prepared by the method for preparing the ion sieve according to any one of claims 1-6.

8. The application of the ion sieve according to claim 7 in selectively adsorbing cesium ions in seawater, nuclear waste liquid, salt lake brine and geothermal water.

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