A mineral composite defluorination material, its preparation method and application

Abstract

This invention provides a mineral composite defluorination material, its preparation method, and its application. The method involves sequentially adding magnesium salt and zeolite to water, ultrasonically mixing, then dissolving in citric acid, followed by adding anhydrous ethanol and heating to obtain a reaction solution. The reaction solution is then heated to a gel-like state, dried, and subjected to a first calcination. After cooling, a second calcination is performed to obtain the final product, which is then ground to obtain the mineral composite defluorination material. This method results in smaller, porous magnesium oxide particles with a larger specific surface area and smaller pore size, which is beneficial for defluorination of fluoride. ‑ During the adsorption process, MgO reacts with water to form Mg(OH)2, and then OH... ‑ With F ‑ Further reaction, increased F ‑ Removal efficiency, and the Mg in this material 2+ The low leaching rate effectively solves the problem of unstable magnesium oxide properties after zeolite loading, and the Mg content is low. 2+ The problem of excessive leaching is addressed, but the material's adsorption performance is improved, and it also possesses antibacterial properties, making it a promising candidate for application.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water treatment, and particularly relates to a mineral composite fluorine removal material and a preparation method and application thereof. BACKGROUND

[0002] Fluoride pollution of water has been recognized as one of the most serious problems worldwide. The industrial wastewater discharge standard of China requires that the mass concentration of fluoride therein is below 10 mg / L. According to the regulation of the World Health Organization, the concentration of fluoride in drinking water exceeding 1.5 mg / L will cause harm to human health, and long-term drinking of high-fluoride water will cause dental fluorosis and skeletal fluorosis. In view of the toxic effect of fluoride on human health, it is very urgent to find an effective and reliable technology to remove excessive fluoride in water environment. There are various technologies for removing fluoride in water environment, and the commonly used ones are precipitation method, membrane method and adsorption method. Compared with the precipitation method and the membrane method, the adsorption method has been proved to be a practical method for removing excessive fluoride in drinking water, because it has the advantages of low cost, easy operation, high removal rate and reusable adsorbent. However, the selection of adsorbent in the adsorption method is a key problem.

[0003] Magnesium oxide has good electrostatic attraction, is a suitable adsorbent for anions, and is cheap, environmentally friendly, non-toxic, has the least impact on the environment, and has low solubility. The sludge formed in the water treatment process is more easily precipitated and filtered out than the sludge formed by other alkalis. Artificial zeolite is composed of silicates and aluminates, has a porous structure and a highly regular crystal structure, has a large specific surface area, and has good adsorption performance. The magnesium oxide is loaded on the zeolite to combine the advantages of the two materials and synthesize a new material with better adsorption performance. However, the system is not mature at present, and relevant studies show that the property of the zeolite loaded with magnesium oxide is unstable, and a large amount of magnesium ions will seep out during the fluorine removal process, which brings new problems to water treatment. SUMMARY

[0004] The present application aims at the above-mentioned deficiencies of the prior art, and provides a mineral composite fluorine removal material and a preparation method and application thereof.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] The first object of the present application is to provide a preparation method of a mineral composite fluorine removal material, comprising the following specific steps:

[0007] Step S1: sequentially adding a magnesium salt and a zeolite into water, ultrasonically mixing, then adding citric acid to dissolve, and then adding anhydrous ethanol to perform a heating reaction, to obtain a reaction solution;

[0008] Step S2: heating the reaction solution obtained in step S1 into a gel state, drying, then performing a first calcination, cooling, then performing a second calcination, to obtain a final product, and grinding the final product to obtain the mineral composite fluorine removal material.

[0009] Further, in step S1, the concentration of the magnesium salt is 120-130 g / L, the concentration of the zeolite is 1-2 g / L, and the ultrasonic power is 300-500 W for 5-30 min.

[0010] Further, in step S1, the magnesium salt includes any one of magnesium nitrate, magnesium chloride and magnesium sulfate.

[0011] Further, in step S1, the concentration of the citric acid is 40-50 g / L, the stirring temperature is 70-90℃, and the stirring time is 1-4 h.

[0012] Further, in step S2, the drying temperature is 120-150℃, and the drying time is 2-5 h.

[0013] Further, in step S2, the first calcination temperature is 400-500℃, and the first calcination time is 2-3 h.

[0014] Further, the second calcination temperature is 550-650℃, and the second calcination time is 0.5-1 h.

[0015] A second object of the present application is to provide a mineral composite fluoride removal material prepared by the above method.

[0016] A third object of the present application is to provide an application of the above mineral composite fluoride removal material in water treatment.

[0017] A fourth object of the present application is to provide a method for removing fluorine from wastewater by using the above mineral composite fluoride removal material, wherein the dosage of the mineral composite fluoride removal material is 0.1-2 g / L at a pH of 3-4.

[0018] Compared with the prior art, the present application has the following advantages:

[0019] (1) The present application provides a mineral composite fluoride removal material, a preparation method and an application thereof. The magnesium salt and the zeolite are sequentially added to water, ultrasonically mixed, then citric acid is added for dissolution, followed by the addition of anhydrous ethanol for heating reaction to obtain a reaction liquid. The reaction liquid is heated to be gel-like, then first calcination is performed. After cooling, second calcination is performed to obtain a final product, which is ground to obtain the mineral composite fluoride removal material. This method forms smaller magnesium oxide particles with a porous structure, has a larger specific surface area and a smaller pore size, and is beneficial to the adsorption of F - In the adsorption process, MgO reacts with water to generate Mg(OH)2, then OH - further reacts with F - to improve the removal efficiency of F - , and the Mg 2+The amount of exudation is low, and the effective solution is that the nature of the zeolite loaded magnesium oxide is unstable, Mg 2+ The problem of a large amount of exudation is solved, the adsorption performance of the material is improved (the maximum adsorption capacity is up to 115.4 mg / g), the material also has antibacterial performance, and has good application prospect.

[0020] (2) The preparation method is simple and low in cost, the mineral composite defluorination material prepared has simple use method, good defluorination effect, antibacterial performance, good market value and application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 SEM images of the mineral composite defluorination material prepared in Examples 1-5 and the MgO material prepared in Comparative Example 1;

[0022] Figure 2 TEM images of the mineral composite defluorination material prepared in Examples 1-5, the MgO material prepared in Comparative Example 1 and the Zeolite material prepared in Comparative Example 2;

[0023] Figure 3 XRD images of the mineral composite defluorination material prepared in Examples 1-5 and the MgO material prepared in Comparative Example 1, the Zeolite material of Comparative Example 2;

[0024] Figure 4 BET images of the Zeo 20 -MgO material prepared in Example 2;

[0025] Figure 5 Adsorption effect comparison chart of the mineral composite defluorination material prepared in Examples 1-5 and the MgO material prepared in Comparative Example 1;

[0026] Figure 6 F - adsorption influence trend chart;

[0027] Figure 7 F - concentration influence trend chart of the mineral composite defluorination material;

[0028] Figure 8 Adsorption time of the mineral composite defluorination material on adsorption effect;

[0029] Figure 9 Salt resistance test result chart of the mineral composite defluorination material;

[0030] Figure 10 pH influence trend chart of the mineral composite defluorination material on adsorption effect;

[0031] Figure 11XPS comparison chart of mineral composite fluoride removal material before and after adsorption;

[0032] Figure 12 FTIR comparison chart of mineral composite fluoride removal material before and after adsorption;

[0033] Figure 13 Mg 2+ Leakage trend chart with adsorption time;

[0034] Figure 14 Mineral composite fluoride removal material against E. coli test result chart;

[0035] Figure 15 Mineral composite fluoride removal material against S. aureus test result chart. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the present application clearer, the specific embodiments of the present application will be further described in detail below with reference to the specific examples and drawings. If the specific technology or condition is not specified in the examples, it is carried out according to the technology or condition described in the literature in the art or according to the product instruction. If the reagent or instrument used is not specified by the manufacturer, it is a conventional product that can be obtained from the market.

[0037] The zeolite used in this embodiment is artificial zeolite, (SiO2) x (Al2O3) y , Aladdin, CAS No.: 1318-02-1.

[0038] Example 1

[0039] The preparation method of the mineral composite fluoride removal material provided in this embodiment has the following steps:

[0040] 770mg of magnesium nitrate and 10mg of zeolite (Zeo 10 ) were weighed into 3ml of pure water, ultrasonicated for 5min at 500W, 288mg of citric acid was added, and stirred at 25℃ until dissolved, then 3ml of anhydrous ethanol was added, the stirring temperature was 80℃, and the stirring time was 2h. After the reaction was completed, it was dried at 150℃ for 2h, calcined at 400℃ for 3h, cooled, then calcined at 600℃ for 1h, and the product was collected after grinding, i.e. Zeo 10 -MgO was obtained.

[0041] Example 2

[0042] The preparation method of the mineral composite fluoride removal material provided in this embodiment has the following steps:

[0043] 770mg of magnesium nitrate and 20mg of zeolite (Zeo 20) into 3ml pure water, 500W ultrasonic for 5min, add 288mg citric acid, 25℃ stirring until dissolved, then add 3ml anhydrous ethanol, stirring temperature is 80℃, stirring time is 2h. After the reaction is completed, 150℃ drying for 2h, 400℃ calcination for 3h, after cooling again 600℃ calcination for 1h, after grinding to collect the product, Zeo 20 -MgO.

[0044] Example 3

[0045] The preparation method of the mineral composite fluoride removal material provided in this example has the following steps:

[0046] Take 770mg magnesium nitrate and 40mg zeolite (Zeo 40 ) into 3ml pure water, 500W ultrasonic for 5min, add 288mg citric acid, 25℃ stirring until dissolved, then add 3ml anhydrous ethanol, stirring temperature is 80℃, stirring time is 2h. After the reaction is completed, 150℃ drying for 2h, 400℃ calcination for 3h, after cooling again 600℃ calcination for 1h, after grinding to collect the product, Zeo 40 -MgO.

[0047] Example 4

[0048] The preparation method of the mineral composite fluoride removal material provided in this example has the following steps:

[0049] Take 770mg magnesium nitrate and 80mg zeolite (Zeo 80 ) into 3ml pure water, 500W ultrasonic for 5min, add 288mg citric acid, 25℃ stirring until dissolved, then add 3ml anhydrous ethanol, stirring temperature is 80℃, stirring time is 2h. After the reaction is completed, 150℃ drying for 2h, 400℃ calcination for 3h, after cooling again 600℃ calcination for 1h, after grinding to collect the product, Zeo 80 -MgO.

[0050] Example 5

[0051] The preparation method of the mineral composite fluoride removal material provided in this example has the following steps:

[0052] Take 770mg magnesium nitrate and 120mg zeolite (Zeo 120 ) into 3ml pure water, 500W ultrasonic for 5min, add 288mg citric acid, 25℃ stirring until dissolved, then add 3ml anhydrous ethanol, stirring temperature is 80℃, stirring time is 2h. After the reaction is completed, 150℃ drying for 2h, 400℃ calcination for 3h, after cooling again 600℃ calcination for 1h, after grinding to collect the product, Zeo 120 -MgO.

[0053] Comparative Example 1

[0054] Weigh 770 mg of magnesium nitrate and add it to 3 ml of pure water. Sonicate at 500 W for 5 min, then add 288 mg of citric acid and stir at 25 °C until dissolved. Add 3 ml of anhydrous ethanol and stir at 80 °C for 2 h. After the reaction is complete, dry at 150 °C for 2 h, calcine at 400 °C for 3 h, cool, and then calcine at 600 °C for 1 h. Grind and collect the product to obtain MgO.

[0055] Comparative Example 2

[0056] Weigh 500 mg of zeolite and add it to 3 ml of pure water. Sonicate at 500 W for 5 min, then add 288 mg of citric acid and stir at 25 °C until dissolved. Add 3 ml of anhydrous ethanol and stir at 80 °C for 2 h. After the reaction is complete, dry at 150 °C for 2 h, calcine at 400 °C for 3 h, cool, and then calcine at 600 °C for 1 h. Grind and collect the product to obtain Zeolite.

[0057] To better illustrate the performance and defluorination effect of the mineral composite defluorination material prepared in this invention, the applicant conducted the following research:

[0058] 1. Microscopic morphology characterization of mineral composite defluorination materials

[0059] Characterization of mineral composite defluorination materials: including SEM, TEM, XRD, and BET to characterize the morphology and crystal phase of the materials.

[0060] like Figure 1 and Figure 2 As shown in the figure, the addition of zeolite forms smaller, porous magnesium oxide particles, which is more conducive to the adsorbent's absorption of F. - The adsorption occurs. The adsorbent after adsorption exhibits a sheet-like morphology.

[0061] like Figure 3 As shown in the figure, Zeo 20 The peaks of the MgO material are in the same position as those of MgO, indicating that the main component of the composite material is MgO. However, the peaks of the material are all wider than those of MgO, and the peaks of MgO become lower and lower as the zeolite content increases, which may be due to the addition of zeolite.

[0062] like Figure 4 As shown in the figure, the average specific surface area of ​​MgO is 32.07 m². 2 / g, with an average pore size of 31.76nm, Zeo 20 The average specific surface area of ​​the MgO material is 45.44 m². 2 / g, with an average pore size of 26.00nm. The addition of zeolite can give the material a higher specific surface area and a smaller pore size, which is beneficial for the material to react with F. - Adsorption. It should be noted that the specific surface area and pore size of zeolite cannot be measured.

[0063] 2. Adsorption performance test of mineral composite defluorination materials

[0064] Adsorption experiment: The fluoride ion adsorption effect of the synthesized composite mineral was determined. 1 g / L of the composite mineral was added to a 100 mg / L fluoride solution and stirred for 12 hours to reach adsorption equilibrium. After centrifugation at 8000 rpm for 5 min, the supernatant was collected, and the fluoride concentration in the liquid was measured using a fluoride electrode. - Concentration, based on the F concentration in the solution before and after adsorption. - The concentration difference was used to calculate the effect of the composite mineral on F. - The adsorption capacity was determined. The effects of adsorbent mass, ionic strength, adsorption time, impurity ion concentration (NaCl), and pH on the adsorption effect were measured.

[0065] Mg 2+ Exudation test: using MgO and Zeo 20 -MgO and two other materials adsorb F in the solution - F - The concentration of the adsorbent was 1 g / L and the concentration of the adsorbent was 100 ppm. Samples were taken at adsorption times of 1 h, 2 h, 3 h, 4 h, and 6 h, and filtered through a 0.45 μm filter membrane. The Mg content in the solution was then measured. 2+ The concentration.

[0066] like Figure 5 As shown in the figure, in the MgO of Comparative Example 1 and the MgO of Examples 1-5, Zeo 20 -MgO materials have the best defluorination effect.

[0067] like Figure 6 As shown in the figure, Zeo 20 -MgO materials have a higher adsorption capacity than MgO and Zeolite, and the adsorption capacity for F increases with increasing adsorbent mass. - The adsorption capacity also increases accordingly.

[0068] like Figure 7 As shown in the figure, it can be seen that with F - With increasing concentration, the adsorbent's effect on F - The adsorption capacity of Zeo also increases accordingly, and 20 - The adsorption capacity of MgO material is higher than that of MgO and Zeolite.

[0069] like Figure 8 As shown in the figure, Zeo 20- The MgO material has the fastest fluorine adsorption rate in the first 60 minutes of adsorption, and the rate slows down but still shows an upward trend. The adsorption rate reaches more than 90% at 360 minutes, while the adsorption amount of MgO shows a downward trend after 180 minutes.

[0070] like Figure 9 As shown in the figure, the NaCl concentration has little effect on the fluoride absorption of the adsorbent, indicating that the mineral composite fluoride removal material has salt resistance.

[0071] like Figure 10 As shown, Zeo 20 - The adsorption capacity of the MgO material was higher than that of the control group. Under strongly acidic conditions (pH=3), the adsorption effect of the adsorbent was the best, with an adsorption rate of 96.71%. Under strongly alkaline conditions (pH=11), the effect was the worst. Even at pH=9, the adsorption rate reached more than 90%.

[0072] like Figure 11 As shown in the figure, from the O1s spectrum, the bond energies of Mg-O and Mg-OH before adsorption are 530 eV and 532 eV, respectively, with little difference in their contents. However, the adsorbed F... - The peak is located around 532 eV, and the peak at 530 eV disappears, containing only Mg-OH. These results indicate that during adsorption, MgO reacts with water to form Mg(OH)2, and then Mg(OH)2 reacts with F... - Further reactions.

[0073] like Figure 12 As shown in the figure, the adsorption of F - The appearance of peak 3693 in the complex later confirmed that the formation of -OH favors F - Adsorption.

[0074] like Figure 13 As shown in the figure, the adsorption of F - The appearance of peak 3693 in the complex later confirmed that the formation of -OH favors F - Adsorption.

[0075] like Figure 14 As shown in the figure, it can be seen that with the increase of adsorption time, Zeo 20 -MgO material Mg 2+ The leaching rate is much lower than that of MgO materials. Within 2-5 hours of adsorption, Zeo 20 -MgO material Mg 2+ The exudate concentration is no higher than 0.7 mg / L.

[0076] 3. Antibacterial properties of mineral composite defluorination materials

[0077] Antibacterial test: The antibacterial properties of magnesium oxide-zeolite composites were evaluated using the plate coating method.

[0078] like Figure 14 and 15 As shown, it can be seen from Zeo 20 -MgO materials showed good antibacterial properties against Escherichia coli and Staphylococcus aureus.

[0079] For any points not covered above, existing technologies shall apply.

[0080] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for producing a mineral composite defluoridation material, characterized by, The method comprises the following specific steps: S1, adding magnesium salt and zeolite into water in sequence, mixing uniformly under ultrasonic, then adding citric acid to dissolve, and then adding anhydrous ethanol to perform heating reaction to obtain a reaction solution; S2, heating the reaction solution obtained in step S1 into a gel, drying, then performing first calcination, and after cooling, performing second calcination to obtain a final product, and grinding to obtain a mineral composite fluoride removal material; the first calcination is performed at a temperature of 400-500 DEG C for 2-3 h; the second calcination is performed at a temperature of 550-650 DEG C for 0.5-1 h.

2. The production method according to claim 1, wherein In step S1, the concentration of the magnesium salt is 120-130 g / L, the concentration of the zeolite is 1-2 g / L, and the ultrasonic is performed at 300-500 W for 5-30 min.

3. The production method according to claim 1, wherein The magnesium salt includes any one of magnesium nitrate, magnesium chloride and magnesium sulfate.

4. The production method according to claim 2, wherein In step S1, the concentration of the citric acid is 40-50 g / L.

5. The production method according to claim 1, wherein In step S2, the drying is performed at a temperature of 120-150 DEG C for 2-5 h.

6. A mineral composite fluoride removal material prepared by the preparation method in any one of claims 1-5.

7. Application of the mineral composite fluoride removal material in claim 6 in water treatment.

8. A method for removing fluorine from waste water using the mineral composite fluorine removal material according to claim 6, characterized in that, The dosage of the mineral composite fluoride removal material is 0.1-2 g / L under the condition that the pH is 3-4.

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