Modified zeolite defluorination adsorbent as well as preparation method and application thereof
By activating natural clinoptilolite with hydrochloric acid and hydrolyzing it at high temperature to support lanthanum compounds, a modified zeolite fluoride removal adsorbent was prepared. This solved the problems of large modifier dosage and interference from coexisting anions, achieving efficient and low-cost fluoride ion removal.
Patent Information
- Application Number
- CN202510956733.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-11
- Publication Date
- 2025-11-11
AI Technical Summary
Existing modified adsorbents require large amounts of modifiers to remove fluoride ions from mine water, have poor resistance to interference from coexisting anions, and are expensive and difficult to apply on a large scale using traditional preparation methods.
Using natural clinoptilolite as a base, a modified zeolite fluoride adsorbent was prepared by activating it with hydrochloric acid and hydrolyzing it at high temperature to support lanthanum compounds. This process avoids introducing too many hydroxyl groups and enhances the selective adsorption of fluoride ions.
It achieves efficient removal of fluoride ions from highly mineralized mine water, requires less modifier, produces stable effluent quality, has a simple treatment process, and reduces costs and environmental risks.
Smart Images
Figure CN120919965A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of mine water treatment technology, and in particular to a modified zeolite defluorination adsorbent, its preparation method, and its application. Background Technology
[0002] According to statistics, F in coal mine water in some areas of the Yellow River Basin in my country - The concentration of fluoride ions is 1.5-10 mg / L. According to the current Chinese standard "Technical Guidelines for Comprehensive Utilization of Mine Water" (GB / T 41019-2021), mine water discharge from the Yellow River Basin must comply with Class III requirements of the "Surface Water Environmental Quality Standard" (GB 3838-2002), where the fluoride ion concentration is ≤1.0 mL. Excessive intake of fluoride ions can harm human health and inhibit the growth of vegetation and crops.
[0003] Methods for removing low concentrations of fluoride ions from mine water generally include adsorption, chemical fluoride removal, ion exchange, and membrane separation. Chemical fluoride removal involves adding composite reagents to remove fluoride ions; however, adding large amounts of reagents can lead to residues in the water, introducing new pollutants and increasing the difficulty of subsequent mine water treatment. It also generates large amounts of sludge and may even produce hazardous waste, increasing treatment costs and environmental risks. Ion exchange resins have limited exchange capacity, are expensive, require frequent regeneration, and produce secondary pollution such as acids and alkalis; waste resin is classified as hazardous waste. Adsorption, on the other hand, offers advantages such as high defluorination efficiency, low operating costs, simple equipment, and convenient and safe operation, making it the most commonly used technology for defluorination in mine water. The mechanisms of adsorption defluorination mainly include coordination, ion exchange, van der Waals forces, and hydrogen bonding. Modified adsorbents are a crucial research area in adsorption defluorination.
[0004] In mining areas, hydroxyapatite is often used as an adsorbent in adsorption processes. However, hydroxyapatite has low selectivity for fluoride ions, resulting in low adsorption capacity, large dosage requirements, and poor adaptability to coexisting anions. Traditional modified adsorbent preparation methods include precipitation, layered double hydroxide (LDH) precipitation, and hydrothermal synthesis. For precipitation and LDH precipitation, the preparation process typically uses excess NaOH or ammonia to fix metal ions on the substrate surface, which introduces excessive hydroxyl groups. In fluoride removal applications, the adsorbent is selected based on its ability to adsorb fluoride ions. -The pH value is a crucial influencing factor. In fluoride-containing mine water, a large number of anions exchange with the hydroxyl groups on the surface of the adsorbent material, displacing excess hydroxyl groups and significantly increasing the pH value, deviating from the optimal range for fluoride removal. This results in a decrease in the adsorbent's adsorption capacity and poor adsorption efficiency. Hydrothermal synthesis typically does not require high-temperature sintering to prepare crystalline powders. Under hydrothermal conditions, metastable or other special condensed-state compounds can be synthesized, and the prepared crystals are relatively stable. However, most research on this method is limited to the preparation of powdered oxides, which has stringent preparation conditions, high costs, and is difficult to promote on a large scale.
[0005] To address the problems in the preparation of commonly used modified adsorbents, such as the large amount of modifiers required and the poor resistance of adsorbent materials to interference from coexisting anions, there is an urgent need to develop a new type of modified fluoride removal adsorbent that can efficiently remove fluoride ions from highly mineralized mine water through multiple mechanisms, improve the comprehensive utilization efficiency of mine water, and effectively alleviate the contradiction between sustainable development of coal mining enterprises and water resource shortage. Summary of the Invention
[0006] The primary objective of this invention is to provide a modified zeolite defluorination adsorbent that can efficiently remove fluoride ions from highly mineralized mine water through a variety of mechanisms.
[0007] The second objective of this invention is to provide a method for preparing a modified zeolite defluorination adsorbent, which aims to solve the problems of large amounts of modifier used in the preparation of traditional modified adsorbent materials and poor resistance to interference from coexisting anions during use.
[0008] The present invention provides a method for preparing a modified zeolite defluorination adsorbent, comprising the following steps: S1. Natural clinoptilolite is immersed in hydrochloric acid solution, shaken, washed, and dried to obtain activated natural clinoptilolite; S2. The activated natural clinoptilolite is placed in a lanthanum salt solution, impregnated and stirred for a period of time, then heated and stirred for high-temperature hydrolysis. After hydrolysis, it is filtered, and the resulting solidified material is dried to obtain a modified zeolite defluorination adsorbent.
[0009] Preferably, in step S1, the particle size of the natural clinoptilolite is 100-300 mesh.
[0010] Preferably, in step S1, the concentration of the hydrochloric acid solution is 0.1-0.5 mol / L; the solid-liquid ratio between the natural clinoptilolite and the hydrochloric acid solution is 1:10-1:20 (g / mL).
[0011] Preferably, in step S1, the oscillation speed is 180-220 r / min and the oscillation time is 1.8-2.5 h.
[0012] Preferably, in step S2, the solid-liquid ratio of the activated natural clinoptilolite to the lanthanum salt solution is 1:10 (g / mL); the concentration of lanthanum ions in the lanthanum salt solution is 18-55 mmol / L. The lanthanum salt in the lanthanum salt solution is preferably lanthanum chloride heptahydrate.
[0013] Preferably, step S2 is as follows: the activated natural clinoptilolite is placed in a lanthanum salt solution and impregnated and stirred at 25-85°C for 0.5-2.5 hours. Then, the temperature is raised to 105-255°C and stirred for another 1-1.5 hours for high-temperature hydrolysis. After filtration, the resulting solidified material is dried at 105-205°C for 0.8-1.5 hours to obtain the modified zeolite defluorination adsorbent.
[0014] The present invention also provides a modified zeolite defluorination adsorbent prepared by the above-mentioned method.
[0015] This invention provides the application of the above-mentioned modified zeolite defluorination adsorbent in removing fluoride ions from highly salinized fluoride-containing mine water.
[0016] Preferably, the pH range of the high-mineralization, fluoride-containing mine water to be treated is 3.0-9.0; F - Concentration of 1.5-10 mg / L; CO3 2- HCO3 - SO4 2- Concentrations less than 500 mg / L; Cl - Concentration less than 2000 mg / L.
[0017] Preferably, the pH of the high-mineralization fluoride-containing mine water to be treated is adjusted to 4.0-6.0. The modified zeolite defluorination adsorbent is added to the high-mineralization fluoride-containing mine water at a solid-liquid ratio of 1:1-5:1 (g / L), and the mixture is reacted with shaking at 15-45℃ for 2-12 hours. A 5-15% (w / w) acid or alkali solution is used to adjust the pH of the high-mineralization fluoride-containing mine water.
[0018] Beneficial effects: The modified zeolite defluoridation adsorbent provided by this invention can remove fluoride ions from highly mineralized fluoride-containing mine water through multiple mechanisms. It has the advantages of simple preparation process, low amount of modifier used, and strong resistance to interference from coexisting anions. It has a high removal effect on fluoride ions in mine water, stable effluent quality, and simple treatment process.
[0019] The modified zeolite defluorination adsorbent in this invention uses natural clinoptilolite as the base material, which has high mechanical strength and acid and alkali resistance, and can provide a large number of loading sites, thus exhibiting good loading performance for modified metal ions.
[0020] In preparing the modified zeolite defluorination adsorbent, this invention first activates natural clinoptilolite with hydrochloric acid. This process removes impurity metal ions from the zeolite channels, improves the pore structure, expands the pore size, and increases the pore volume, thereby enhancing its ability to adsorb La. 3+ The loading capacity is enhanced; on the other hand, acid activation introduces H+. + Acidic groups alter the surface properties of natural zeolite, improving the modified material's resistance to F under neutral and alkaline conditions. - The adsorption performance of activated natural clinoptilolite, loaded with a polycrystalline lanthanum compound via high-temperature hydrolysis, enhances its adsorption capacity for F in water. - It possesses highly efficient selective adsorption capacity and effectively improves the zeolite structure, thereby achieving the removal of F from mine water with high concentrations of coexisting anions. - Its function.
[0021] The loading mechanism of the modified zeolite defluorination adsorbent in this invention is quite different from that of traditional methods, and it does not introduce a large number of hydroxyl ions. It utilizes natural clinoptilolite to defluorinate La... 3+ Natural adsorption capacity and La 3+ Its inherent high-temperature hydrolysis properties make La 3+ By supporting zeolite in the form of polycrystalline phases such as La2(Si2O7), La2(C2O4)3, La(OH)3, and LaCl3·7H2O, the introduction of hydroxyl groups into the system is reduced. Furthermore, the preparation method of high-temperature hydrolysis followed by low-temperature calcination mitigates the impact of high-temperature calcination on La2(Si2O7), La2(C2O4)3, La(OH)3, and LaCl3·7H2O. 3+ Influenced by the zeolite structure, La was preserved. 3+ For F - High selective adsorption. Therefore, this invention significantly reduces the amount of lanthanum modifier used in lanthanum-modified zeolite and effectively improves the adsorption material's resistance to interference from coexisting ions, thereby achieving the removal of F from highly mineralized fluoride-containing mine water. - The effect of treating high-mineralized fluoride-containing mine water, after which F... - The mass concentration is less than 1 mg / L. Attached Figure Description
[0022] Figure 1 This is a scanning electron microscope image of natural clinoptilolite used in Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of activated natural clinoptilolite in Example 1 of the present invention; Figure 3 This is a scanning electron microscope image of the modified zeolite defluorination adsorbent obtained in Example 1 of the present invention; Figure 4 The XRD patterns of activated natural clinoptilolite and modified zeolite defluorination adsorbents prepared in Example 1 of this invention are shown below. Figure 5XPS image of the modified zeolite defluorination adsorbent prepared in Example 1 of this invention; Figure 6 The XRD patterns are of the modified zeolite defluorination adsorbent prepared in Example 1 of the present invention and the modified zeolite defluorination adsorbent after defluorination. Figure 7 The Fourier transform infrared spectra of the activated natural clinoptilolite, the modified zeolite defluorination adsorbent, and the defluorinated modified zeolite defluorination adsorbent prepared in Example 1 of this invention are shown. Detailed Implementation
[0023] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0024] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0026] Example 1 A method for preparing a modified zeolite defluorination adsorbent includes the following steps: S1. Natural clinoptilolite with a particle size of 150 mesh was impregnated in a hydrochloric acid solution with a concentration of 0.5 mol / L. The solid-liquid ratio between the natural clinoptilolite and the hydrochloric acid solution was 1:15 (g / mL). After shaking at a vibration speed of 200 r / min for 2 h, the solid and liquid were separated. The solidified material was washed until neutral and dried to obtain activated natural clinoptilolite. S2. The activated natural clinoptilolite was placed in a lanthanum salt solution of lanthanum chloride heptahydrate, with a solid-liquid ratio of 1:10 (g / mL) between the activated natural clinoptilolite and the lanthanum salt solution. The concentration of lanthanum ions in the lanthanum salt solution was 18.16 mmol / L. In the first stage, the mixture was impregnated and stirred at 25°C for 2 hours. In the second stage, the temperature was raised to 205°C and stirred for 70 minutes for high-temperature hydrolysis. After hydrolysis, the mixture was filtered, and the resulting solidified material was dried at 105°C for 50 minutes to obtain the modified zeolite defluorination adsorbent.
[0027] The scanning electron microscope (SEM) images of natural clinoptilolite, activated natural clinoptilolite, and modified zeolite fluoride adsorbents prepared in the above method are shown below. Figure 1 , Figure 2 and Figure 3 As shown.
[0028] Example 2 A method for preparing a modified zeolite defluorination adsorbent includes the following steps: S1. Natural clinoptilolite with a particle size of 100 mesh was impregnated in a hydrochloric acid solution with a concentration of 0.1 mol / L. The solid-liquid ratio between the natural clinoptilolite and the hydrochloric acid solution was 1:20 (g / mL). After shaking at a vibration speed of 180 r / min for 2.5 h, the solid and liquid were separated. The solidified material was washed until neutral and dried to obtain activated natural clinoptilolite. S2. The activated natural clinoptilolite was placed in a lanthanum salt solution of lanthanum chloride heptahydrate, with a solid-liquid ratio of 1:10 (g / mL) between the activated natural clinoptilolite and the lanthanum salt solution. The concentration of lanthanum ions in the lanthanum salt solution was 18 mmol / L. In the first stage, the mixture was impregnated and stirred at 85°C for 0.5 h. In the second stage, the temperature was raised to 255°C and stirred for 70 min for high-temperature hydrolysis. After hydrolysis, the mixture was filtered, and the resulting solidified material was dried at 205°C for 48 min to obtain the modified zeolite defluorination adsorbent.
[0029] Example 3 A method for preparing a modified zeolite defluorination adsorbent includes the following steps: S1. Natural clinoptilolite with a particle size of 300 mesh was impregnated in a hydrochloric acid solution with a concentration of 0.3 mol / L. The solid-liquid ratio between the natural clinoptilolite and the hydrochloric acid solution was 1:10 (g / mL). After shaking at a vibration speed of 220 r / min for 1.8 h, the solid and liquid were separated. The solidified material was washed until neutral and dried to obtain activated natural clinoptilolite. S2. The activated natural clinoptilolite was placed in a lanthanum salt solution of lanthanum chloride heptahydrate, with a solid-liquid ratio of 1:10 (g / mL) between the activated natural clinoptilolite and the lanthanum salt solution. The concentration of lanthanum ions in the lanthanum salt solution was 55 mmol / L. In the first stage, the mixture was impregnated and stirred at 50°C for 2.5 h. In the second stage, the temperature was raised to 105°C and stirred for 70 min for high-temperature hydrolysis. After hydrolysis, the mixture was filtered, and the resulting solidified material was dried at 150°C for 90 min to obtain the modified zeolite defluorination adsorbent.
[0030] Comparative Example 1: Unmodified natural clinoptilolite was used.
[0031] Comparative Example 2: Unactivated natural clinoptilolite with a particle size of 150 mesh was placed in a lanthanum salt solution of lanthanum chloride heptahydrate. After activation, the solid-liquid ratio of natural clinoptilolite to lanthanum salt solution was 1:10 (g / mL). The concentration of lanthanum ions in the lanthanum salt solution was 18.16 mmol / L. In the first stage, the mixture was impregnated and stirred at 25 °C for 2 h. In the second stage, the temperature was raised to 205 °C and stirred for 70 min for high-temperature hydrolysis. After hydrolysis, the mixture was filtered, and the resulting solidified product was dried at 105 °C for 50 min to obtain the product, unactivated modified zeolite.
[0032] Comparative Example 3: Following the method described in Example 1, only the particle size of the natural clinoptilolite was changed to 30 mesh.
[0033] Comparative Example 4: The method described in Example 1 was followed, except that the drying temperature was changed to 255°C.
[0034] Comparative Example 5: The method described in Example 1 was followed, except that the drying time was changed to 2 hours.
[0035] Application Test Case 1 Application of a modified zeolite defluoridation adsorbent in removing fluoride ions from highly salinized fluoride-containing mine water. The pH of the highly salinized fluoride-containing mine water to be treated is 7.98, and the CO3 content is... 2- HCO3 - SO4 2- Concentrations less than 500 mg / L; Cl - For concentrations less than 2000 mg / L, the pH of the high-mineralization fluoride-containing mine water to be treated was adjusted to 5 using a 10% hydrochloric acid or sodium hydroxide solution. Then, the modified zeolite defluorination adsorbent prepared in Example 1 was added to the high-mineralization fluoride-containing mine water to be treated. The solid-liquid ratios of the added amounts are shown in Table 1. The mixture was then shaken at 200 r / min for 2 hours at 25°C using a constant temperature water bath shaker.
[0036] Eight groups of high-mineralization fluoride-containing mine water samples were collected and tested, among which F - The initial concentration, total dissolved solids (TDS), dosage of modified zeolite defluoridating adsorbent, and effluent fluoride concentration are shown in Table 1. It can be seen that the effluent fluoride concentration... - The concentrations were all below 1 mg / L, meeting the Class III limit requirements of the "Surface Water Environmental Quality Standard".
[0037] Table 1
[0038] Performance testing: The activated natural clinoptilolite prepared in Example 1 and the modified zeolite defluorination adsorbent prepared in Example 1 were subjected to XRD tests. The test results are as follows: Figure 4 As shown, H-NZ is activated natural clinoptilolite, and La-H-NZ is a modified zeolite defluorination adsorbent.
[0039] The modified zeolite defluorination adsorbent prepared in Example 1 was subjected to XPS analysis. The XPS spectrum is shown below. Figure 5 As shown in the figure, the marked areas represent the locations where peak values change. We can see the peak changes in the positions of the zeolite silicate and carbonic acid components, which can be attributed to the combination of lanthanum and zeolite. Additionally, the appearance of the lanthanum hydroxide peak indicates the successful conversion of lanthanum hydroxide via high-temperature hydrolysis. However, because the lanthanum modification dosage used in this invention is relatively small—compared to the traditional lanthanum chloride:zeolite mass ratio of 1:1 or 1:2—the mass ratio between the lanthanum salt modifier and the activated natural clinoptilolite in this invention is approximately 1:15-40, resulting in a relatively smaller degree of peak variation.
[0040] In the traditional preparation process of lanthanum-modified zeolites, precipitation is typically used for loading. This process involves loading lanthanum onto the zeolite. 3+ La's natural adsorption capacity makes it 3+ Entering the zeolite channels, then using excess NaOH or ammonia to remove La 3+ The zeolite is immobilized in the form of La(OH)3. This method results in an excessive number of hydroxyl groups on the surface of the adsorbent material. In defluorination applications, these hydroxyl groups on the zeolite surface will react with F... - Ion exchange occurs, releasing a large number of hydroxyl groups into the reaction system. These hydroxyl groups then react with F... - Competitive adsorption occurs, which simultaneously raises the solution pH, thereby inhibiting lanthanum's adsorption to F. - The adsorption of F is further exacerbated by the presence of coexisting anions, making it difficult for traditional lanthanum-modified zeolites to adsorb F in systems with high concentrations of coexisting anions. - Secondly, most traditional studies on lanthanum-modified zeolites employ high-temperature calcination to further fix the lanthanum-modified zeolite. Research indicates that high-temperature calcination can cause La... 3+ The combination with the [O] structure in the zeolite framework allows La to... 3+ The transformation from the supported form of La(OH)3 to LaO3 occurs, and the bonding becomes tighter and the structure more stable with increasing calcination temperature and time. However, an overly stable [La-O] structure can lead to La… 3+ For F - The effective adsorption sites are reduced, which reduces the effectiveness of F. - The selective adsorption capacity decreases. Therefore, a large amount of lanthanum modifier is required in the preparation of lanthanum-modified zeolites, resulting in resource waste and increased costs.
[0041] The modified zeolite defluorination adsorbent prepared in Example 1 and the modified zeolite defluorination adsorbent after the above treatment were subjected to XRD tests. The test results are shown in the figure. Figure 6 As shown in the figure, La-H-NZ is the modified zeolite defluorination adsorbent, and La-H-NZ-F is the modified zeolite defluorination adsorbent after defluorination. The figure sufficiently demonstrates the successful adsorption of fluoride ions by the modified zeolite defluorination adsorbent and the adsorption form.
[0042] Fourier transform infrared spectroscopy analysis was performed on the activated natural clinoptilolite, the modified zeolite defluorination adsorbent prepared in Example 1, and the modified zeolite defluorination adsorbent after the above-mentioned defluorination treatment. The spectra are shown in the figure. Figure 7 As shown in the figure, the framework structure of the zeolite did not change significantly after lanthanum loading and defluorination, indicating that the modified zeolite defluorination adsorbent has good structural stability. Furthermore, in the changes of the -OH peak, Si-O-Al peak, and CO peak belonging to the zeolite structure, the peaks changed slightly after lanthanum loading; however, these peaks changed more significantly after defluorination. It is speculated that lanthanum modification causes lanthanum to combine with zeolite components, transforming Si-O-Al in the zeolite structure into Si-O-La, and CO and H₂O combining with La. Therefore, the basic structure of the zeolite did not change significantly after lanthanum loading; after defluorination, the La... 3+ With F - The polycrystalline lanthanum bonded to zeolite transforms into La-F and La-OF, resulting in a significant weakening of Si-O-Al, CO, and -OH peaks in the lanthanum-loaded zeolite, consistent with XRD analysis results.
[0043] The modified zeolite defluoridation adsorbents prepared in Examples 2-3 and the products of Comparative Examples 1-5 were used to treat the high-mineralization fluoride-containing mine water of Sample 7 in Table 1 according to the method of Application Test Example 1. The effluent water quality is shown in Table 2. In Table 2, the initial mass concentration of fluoride ions in the fluoride-containing mine water was 10 mg / L; the dosage of modified zeolite was 1.5 g / L; and the TDS was 100-1000 mg / L.
[0044] Table 2
[0045] As shown in Table 1, the fluoride concentration in the treated effluent is the best among the modified zeolite defluoridation adsorbents prepared in Example 1, making it the optimal example. The modified zeolite defluoridation adsorbents obtained in Examples 1-3 all showed significantly better defluoridation effects than those in Comparative Examples 1-5. Using the modified zeolite described in this invention for removing fluoride ions from highly salinized fluoride-containing mine water, fluoride ions can be stably removed from the water, ensuring that the fluoride ion concentration in the treated water is below the discharge limit of 1.0 mg / L.
[0046] Application Test Examples 2-3 and Application Test Comparative Examples 1 and 2 both treated the high-mineralization fluoride-containing mine water of Sample 7 in Table 1, and the treatment methods were basically the same as those in Application Test Example 1.
[0047] Application Test Example 2: Application of a modified zeolite defluoridation adsorbent in removing fluoride ions from highly salinized fluoride-containing mine water. The pH of the highly salinized fluoride-containing mine water to be treated is 7.98, and the CO3 content is... 2- HCO3 - SO4 2- Concentrations less than 500 mg / L; Cl - For concentrations less than 2000 mg / L, the pH of the high-mineralization fluoride-containing mine water to be treated was adjusted to 4 using a 10% hydrochloric acid or sodium hydroxide solution. Then, the modified zeolite defluorination adsorbent prepared in Example 1 was added to the high-mineralization fluoride-containing mine water to be treated at a solid-liquid ratio of 1.5:1 (g / L). The mixture was then shaken at 200 r / min for 12 h at 35°C using a constant temperature water bath shaker.
[0048] Application Test Example 3: Application of a modified zeolite defluoridation adsorbent in removing fluoride ions from highly salinized fluoride-containing mine water. The pH of the highly salinized fluoride-containing mine water to be treated is 7.98, and the CO3 content is... 2- HCO3 - SO4 2- Concentrations less than 500 mg / L; Cl - For concentrations less than 2000 mg / L, the pH of the high-mineralization fluoride-containing mine water to be treated was adjusted to 6 using a 10% hydrochloric acid or sodium hydroxide solution. Then, the modified zeolite defluorination adsorbent prepared in Example 1 was added to the high-mineralization fluoride-containing mine water to be treated at a solid-liquid ratio of 1.5:1 (g / L). The mixture was then shaken at 200 r / min for 6 hours at 45°C using a constant temperature water bath shaker.
[0049] Application test comparison example 1: The only difference from Application Test Example 1 is that the pH of the highly mineralized fluoride-containing mine water to be treated is adjusted to 7.
[0050] Application test comparison example 2: The only difference from Application Test Example 1 is that the pH of the highly mineralized fluoride-containing mine water to be treated was adjusted to 9.
[0051] The modified zeolite defluorination adsorbent prepared in Example 1 was used to treat the high-mineralization fluoride-containing mine water of sample 7 in Table 1 according to the methods of application test examples 2 and 3, and application test comparative examples 1 and 2. The effluent water quality is shown in Table 3.
[0052] Table 3
[0053] In summary, it can be seen that the test results of Application Test Example 1 are better. Adjusting the pH range of the high-mineralization fluoride-containing mine water to be treated to 4-6 is more conducive to the subsequent fluoride adsorption treatment. Its fluoride removal effect is far better than that of Application Test Comparative Examples 1 and 2.
[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing a modified zeolite defluorination adsorbent, characterized in that, Includes the following steps: S1. Natural clinoptilolite is immersed in hydrochloric acid solution, shaken, washed, and dried to obtain activated natural clinoptilolite; S2. The activated natural clinoptilolite is placed in a lanthanum salt solution, impregnated and stirred for a period of time, then heated and stirred for high-temperature hydrolysis. After hydrolysis, it is filtered, and the resulting solidified material is dried to obtain a modified zeolite defluorination adsorbent.
2. The preparation method of the modified zeolite defluorination adsorbent according to claim 1, characterized in that, In step S1, the particle size of the natural clinoptilolite is 100-300 mesh.
3. The preparation method of the modified zeolite defluorination adsorbent according to claim 1, characterized in that, In step S1, the concentration of the hydrochloric acid solution is 0.1-0.5 mol / L; the solid-liquid ratio between the natural clinoptilolite and the hydrochloric acid solution is 1:10-1:20 (g / mL).
4. The preparation method of the modified zeolite defluorination adsorbent according to claim 1, characterized in that, In step S1, the oscillation speed is 180-220 r / min; the oscillation time is 1.8-2.5 h.
5. The preparation method of the modified zeolite defluorination adsorbent according to claim 1, characterized in that, In step S2, the solid-liquid ratio of activated natural clinoptilolite to lanthanum salt solution is 1:10 (g / mL); the concentration of lanthanum ions in the lanthanum salt solution is 18-55 mmol / L.
6. The preparation method of the modified zeolite defluorination adsorbent according to claim 1, characterized in that, The specific steps of step S2 are as follows: the activated natural clinoptilolite is placed in a lanthanum salt solution and impregnated and stirred at 25-85℃ for 0.5-2.5h. Then, the temperature is raised to 105-255℃ and stirred for another 1-1.5h for high-temperature hydrolysis. After filtration, the solidified product obtained by filtration is dried at 105-205℃ for 0.8-1.5h to obtain the modified zeolite defluorination adsorbent.
7. A modified zeolite defluorination adsorbent prepared by the preparation method of any one of claims 1-6.
8. The application of the modified zeolite defluorination adsorbent of claim 7 in removing fluoride ions from highly salinized fluoride-containing mine water.
9. The application according to claim 8, characterized in that, The pH range of the highly mineralized, fluoride-containing mine water to be treated is 3.0-9.0; F - Concentration of 1.5-10 mg / L; CO3 2- HCO3 - SO4 2- Concentrations less than 500 mg / L; Cl - Concentration less than 2000 mg / L.
10. The application according to claim 9, characterized in that, The pH value of the high-mineralization fluoride-containing mine water to be treated is adjusted to 4.0-6.
0. The modified zeolite defluorination adsorbent is added to the high-mineralization fluoride-containing mine water to be treated at a solid-liquid ratio of 1:1-5:1 (g / L), and the mixture is shaken and reacted at 15-45℃ for 2-12 hours.