A modified zeolite material for simultaneously removing ammonia nitrogen and phosphate in wastewater and a preparation method thereof

Abstract

The application discloses a modified zeolite material for synchronously removing ammonia nitrogen and phosphate in wastewater and a preparation method thereof. The application takes natural zeolite as a carrier, takes synchronously adsorbing ammonia nitrogen and phosphate as a target, carries out function regulation on the zeolite, modifies and regulates the internal structure and surface physical and chemical properties of the zeolite in a targeted manner, successfully obtains Zr-Na-Z composite material which can efficiently and synchronously remove low-concentration ammonia nitrogen and phosphate, and has a good application prospect in the fields of nitrogen and phosphorus wastewater treatment and lake sediment pollutant passivation. The method is suitable for batch construction of adsorption materials, and the preparation process is simple and efficient. In the adsorption experiment of simulated low-concentration water bodies with a simulated concentration of 10 mg / l ammonia nitrogen and 2 mg / l phosphate, the adsorption capacity of the modified zeolite material prepared by the application for ammonia nitrogen is increased from 2.92 mg / g to 3.52 mg / g, and the adsorption capacity of the modified zeolite material prepared by the application for phosphate is increased from 0 mg / g to 0.94 mg / g, which are both significantly increased.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a modified zeolite material for simultaneously removing ammonia nitrogen and phosphate from wastewater and its preparation method. Background Technology

[0002] The discharge of domestic sewage and industrial wastewater has become a significant source of global water pollution, with a marked increase in nitrogen and phosphorus concentrations in lakes and rivers, leading to serious ecological and environmental problems. The intensifying eutrophication of water bodies not only affects water quality but also has a profound impact on aquatic ecosystems. The large volume and wide distribution of these two types of pollutants have placed enormous pollution pressure on the aquatic environment, severely impacting the self-purification capacity and ecological balance of water bodies. Therefore, effectively controlling the discharge of ammonia nitrogen and phosphorus into water bodies has become a major environmental protection issue that urgently needs to be addressed.

[0003] Natural zeolite, as an important mineral material, possesses excellent ion exchange capacity and adsorption properties. Natural zeolite is a class of hydrous alkali or alkaline earth metal aluminosilicate minerals. Due to its unique crystal structure, it can accommodate cations in the lattice vacancies, thereby achieving ion exchange. The abundant pore structure of natural zeolite enables it to effectively adsorb pollutants in water during water treatment. Compared with synthetic zeolite, natural zeolite is not only inexpensive but also abundant and easily accessible.

[0004] In recent years, research on the removal of ammonia nitrogen using natural zeolites has attracted widespread attention from researchers both domestically and internationally. Through simple modification methods such as salt, high-temperature, and alkali treatment, researchers have successfully prepared several modified zeolites with good ammonia nitrogen removal performance. While these modified zeolites exhibit excellent performance in ammonia nitrogen removal, they still suffer from the drawback of not being able to be regenerated multiple times, limiting their economic viability and sustainability in practical applications.

[0005] On the other hand, phosphorus exists primarily in water as anions, which creates electrostatic repulsion between it and the negatively charged zeolite framework, resulting in poor phosphorus adsorption by natural zeolites. To improve the phosphorus removal capacity of natural zeolites, researchers are exploring various modification methods, including surface modification and the preparation of composite materials.

[0006] For example, Chinese patent document CN111530412A discloses a method for synthesizing a simultaneous denitrification and phosphorus removal adsorbent based on natural zeolite. By introducing lanthanum element during the synthesis of molecular sieves from natural zeolite, a lanthanum-modified molecular sieve adsorbent with simultaneous denitrification and phosphorus removal performance is prepared. The prepared adsorbent has a good adsorption effect on ammonium and phosphate ions, but its ability to remove ammonia nitrogen from wastewater still needs to be further improved. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a modified zeolite material for the simultaneous removal of ammonia nitrogen and phosphate from wastewater, and its preparation method. By first modifying natural zeolite with zirconium and then with sodium, the goal of simultaneously removing ammonia nitrogen and phosphate from wastewater can be achieved.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A method for preparing a modified zeolite material for simultaneous removal of ammonia nitrogen and phosphate from wastewater includes the following steps:

[0010] S1. Add natural zeolite and soluble zirconium salt to deionized water, mix evenly and shake. After shaking is complete, evaporate the deionized water, and then dry, wash and dry again to obtain zirconium-modified natural zeolite.

[0011] S2. Add zirconium-modified natural zeolite to NaCl solution and mix evenly to obtain a solid-liquid mixture. Then, place the solid-liquid mixture in a water bath shaker for shaking treatment. After shaking is completed, take out the solid, wash and dry it to obtain the modified zeolite material.

[0012] Specifically, in step S1, the mass ratio of natural zeolite to soluble zirconium salt is 10:2-6. In some embodiments of the present invention, for example, 10:2, 10:3, 10:4, 10:5, or 10:6 can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0013] The natural zeolite is 40-80 mesh, and the soluble zircon salt is selected from ZrOCl2·8(H2O) or ZrO(NO3)2·2H2O.

[0014] Specifically, in step S1, the ratio of natural zeolite to deionized water is 1g:10-15mL. In some embodiments of the present invention, for example, 1g:10mL, 1g:11mL, 1g:12mL, 1g:13mL, 1g:14mL, and 1g:15mL can be selected; however, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0015] Specifically, in step S1, the rotational speed of the shaking table during the oscillation process is 100-400 r / min. In some embodiments of the present invention, for example, 100 r / min, 200 r / min, 300 r / min, or 400 r / min can be selected; the oscillation time is 18-36 h, for example, 18 h, 24 h, 30 h, or 36 h can be selected; but it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0016] Specifically, in step S2, the ratio of zirconium-modified natural zeolite to NaCl solution is 1g:15-30mL. In some embodiments of the present invention, for example, 1g:15mL, 1g:20mL, 1g:25mL, or 1g:30mL can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] The concentration of the NaCl solution is 0.1-1.5 mol / L, for example, 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.5 mol / L, 0.8 mol / L, 1.0 mol / L, 1.2 mol / L, 1.5 mol / L; but is not limited to the listed values, other unlisted values ​​within the range are also applicable.

[0018] Specifically, in step S2, the rotational speed of the oscillator is 100-300 r / min, for example, 100 r / min, 150 r / min, 200 r / min, 250 r / min, or 300 r / min can be selected; the oscillation time is 4-8 h, for example, 4 h, 5 h, 6 h, 7 h, or 8 h can be selected; but it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0019] The present invention provides a modified zeolite material prepared by the above preparation method.

[0020] The present invention also provides the application of the above-mentioned modified zeolite material in wastewater treatment.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) This invention uses natural zeolite as a carrier and aims to simultaneously adsorb ammonia nitrogen and phosphate. It modifies the function of zeolite, specifically modifies and regulates the internal structure and surface physicochemical properties of zeolite, and successfully obtains a Zr-Na-Z composite material that can efficiently and simultaneously remove low concentrations of ammonia nitrogen and phosphate. It has good application prospects in the fields of nitrogen and phosphorus wastewater treatment and lake sediment pollutant passivation. This method is suitable for batch construction of adsorption materials and the preparation process is simple and efficient.

[0023] (2) In the adsorption experiment of water with a simulated concentration of 10 mg / L ammonia nitrogen and 2 mg / L phosphate, the modified zeolite material prepared in this invention showed a significant increase in adsorption capacity of ammonia nitrogen from 2.92 mg / g to 3.52 mg / g and adsorption capacity of phosphate from 0 mg / g to 0.94 mg / g compared with the original zeolite.

[0024] (3) The applicant also found that the adsorption effect of the adsorbent material obtained by first modifying natural zeolite with zirconium and then with sodium was better than that obtained by first modifying with sodium and then with zirconium. This may be because if sodium modification is performed first, due to the principle of ion exchange used in salt modification, some Na ions will be exchanged out during high-concentration zirconium regulation, resulting in a decrease in its removal efficiency for ammonia nitrogen. However, if zirconium regulation modification is performed first, phosphate removal is carried out using the principle of surface zirconium oxide anion ligand exchange, and the resulting zirconium oxide is more stable, adheres to the zeolite surface, is not easily detached during the next salt modification, and can more efficiently improve its removal rate for ammonia nitrogen. Attached Figure Description

[0025] Figure 1 SEM image of natural zeolite in Comparative Example 1;

[0026] Figure 2 EDS plot of natural zeolite for Comparative Example 1;

[0027] Figure 3 SEM image of the modified zeolite material prepared in Example 1;

[0028] Figure 4 The image shows the EDS diagram of the modified zeolite material prepared in Example 1. Detailed Implementation

[0029] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0030] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.

[0031] The natural zeolite used in this invention has a mesh size of 40-80.

[0032] Example 1

[0033] A method for preparing a modified zeolite material for simultaneous removal of ammonia nitrogen and phosphate from wastewater includes the following steps:

[0034] S1. Add 10g of natural zeolite and 4g of ZrOCl2·8(H2O) to 100mL of deionized water, mix well and shake. The shaking speed of the shaker is 200r / min and the shaking time is 24h. After shaking, place it in a 100℃ water bath to evaporate and remove the deionized water. Transfer the obtained material to a 105℃ oven and dry for 2h. Wash the obtained product 5 times with deionized water and dry it again in a 105℃ oven for 2h to obtain zirconium-modified natural zeolite.

[0035] S2. Add 10g of zirconium-modified natural zeolite to 200mL of 1.0mol / L NaCl solution and mix well to obtain a solid-liquid mixture. Then, place the solid-liquid mixture in a water bath shaker and shake it at a speed of 200r / min, a water temperature of 25℃, and a shaking time of 6h. After shaking, wash it three times with deionized water, collect the solid, and dry it in a 105℃ forced-air drying oven for 12h to obtain the modified zeolite material.

[0036] Example 2

[0037] A method for preparing a modified zeolite material for simultaneous removal of ammonia nitrogen and phosphate from wastewater includes the following steps:

[0038] S1. Add 10g of natural zeolite and 4g of ZrOCl2·8(H2O) to 100mL of deionized water, mix well and shake. The shaking speed of the shaker is 200r / min and the shaking time is 24h. After shaking, place it in a 100℃ water bath to evaporate and remove the deionized water. Transfer the obtained material to a 105℃ oven and dry for 2h. Wash the obtained product 5 times with deionized water and dry it again in a 105℃ oven for 2h to obtain zirconium-modified natural zeolite.

[0039] S2. Add 10g of zirconium-modified natural zeolite to 200mL of 0.1mol / L NaCl solution and mix well to obtain a solid-liquid mixture. Then, place the solid-liquid mixture in a water bath shaker and shake it at a speed of 200r / min, a water temperature of 25℃, and a shaking time of 6h. After shaking, wash it three times with deionized water, collect the solid, and dry it in a 105℃ forced-air drying oven for 12h to obtain the modified zeolite material.

[0040] Compared with Example 1, Example 2 uses a NaCl solution with a concentration of 0.1 mol / L.

[0041] Example 3

[0042] A method for preparing a modified zeolite material for simultaneous removal of ammonia nitrogen and phosphate from wastewater includes the following steps:

[0043] S1. Add 10g of natural zeolite and 4g of ZrOCl2·8(H2O) to 100mL of deionized water, mix well and shake. The shaking speed of the shaker is 200r / min and the shaking time is 24h. After shaking, place it in a 100℃ water bath to evaporate and remove the deionized water. Transfer the obtained material to a 105℃ oven and dry for 2h. Wash the obtained product 5 times with deionized water and dry it again in a 105℃ oven for 2h to obtain zirconium-modified natural zeolite.

[0044] S2. Add 10g of zirconium-modified natural zeolite to 200mL of 1.5mol / L NaCl solution and mix well to obtain a solid-liquid mixture. Then, place the solid-liquid mixture in a water bath shaker and shake it at a speed of 200r / min, a water temperature of 25℃, and a shaking time of 6h. After shaking, wash it three times with deionized water, collect the solid, and dry it in a 105℃ forced-air drying oven for 12h to obtain the modified zeolite material.

[0045] Compared with Example 1, Example 3 changed the concentration of NaCl solution to 1.5 mol / L.

[0046] Comparative Example 1

[0047] Natural zeolite was used as the adsorbent material without any modification treatment.

[0048] Comparative Example 2

[0049] A method for preparing a modified zeolite material includes the following steps:

[0050] 10g of natural zeolite and 4g of ZrOCl2·8(H2O) were added to 100mL of deionized water, mixed evenly, and shaken. The shaking speed of the shaker was 200r / min, and the shaking time was 24h. After shaking, the mixture was placed in a 100℃ water bath to evaporate and remove the deionized water. The resulting material was then transferred to a 105℃ oven and dried for 2h. The product was then washed 5 times with deionized water and dried again in a 105℃ oven for 2h to obtain the modified zeolite material.

[0051] Compared with Example 1, Comparative Example 2 did not undergo sodium ion modification treatment.

[0052] Comparative Example 3

[0053] A method for preparing a modified zeolite material for simultaneous removal of ammonia nitrogen and phosphate from wastewater includes the following steps:

[0054] S1. Add 10g of natural zeolite to 200mL of 1.0mol / L NaCl solution and mix well to obtain a solid-liquid mixture. Then, place the solid-liquid mixture in a water bath shaker and shake it at a speed of 200r / min, a water temperature of 25℃, and a shaking time of 6h. After shaking, wash it three times with deionized water, collect the solid, and dry it in a 105℃ forced-air drying oven for 12h to obtain sodium-modified zeolite.

[0055] S2. Add 10g of sodium-modified zeolite and 4g of ZrOCl2·8(H2O) to 100mL of deionized water, mix well and shake. The shaking speed of the shaker is 200r / min and the shaking time is 24h. After shaking, place it in a 100℃ water bath to evaporate and remove the deionized water. Transfer the obtained material to a 105℃ oven and dry for 2h. Wash the obtained product 5 times with deionized water and dry it again in a 105℃ oven for 2h to obtain the modified zeolite material.

[0056] Compared with Example 1, in Comparative Example 3, natural zeolite was first modified with sodium and then modified with zirconium.

[0057] SEM images of natural zeolite in Comparative Example 1 are as follows: Figure 1 As shown, the EDS of natural zeolite is as follows: Figure 2 As shown, the SEM image of the modified zeolite material prepared in Example 1 is as follows. Figure 3 As shown, the EDS of the modified zeolite material is as follows: Figure 4 As shown in the figure, compared with the original zeolite, the modified zeolite material has no particle fragments on its surface, and the surface becomes more loose, rough and uneven, with obvious grooves. After loading zirconium oxide, more granular substances appear on the surface, and some of the previous grooves are filled. The particles are loosely arranged and relatively evenly dispersed. Compared with the original zeolite, the relative mass ratio of Zr and Na elements on the surface of the modified zeolite material is significantly increased. The relative mass of Na element increases from 0.8% to 1.4%, and the relative mass of Zr element increases from 0% to 10.7%.

[0058] The samples prepared in Examples 1-3 and Comparative Examples 1-3 were respectively added to simulated wastewater. The concentrations of ammonia nitrogen (as N) and phosphate (as P) in the simulated wastewater were 10 mg / L and 2.0 mg / L, respectively. The solution pH was 7.0, the dosage was 2.0 g / L, the adsorption time was 6 h, the temperature was 25 °C, and the water bath shaker speed was 200 r / min. The removal efficiency of ammonia nitrogen and phosphate was determined.

[0059] The experimental results are shown in the table below:

[0060] Ammonia nitrogen adsorption capacity (mg / g) Phosphate adsorption capacity (mg / g) Example 1 3.52 0.94 Example 2 2.87 0.97 Example 3 3.49 0.94 Comparative Example 1 2.92 0 Comparative Example 2 1.61 0.99 Comparative Example 3 3.05 0.88

[0061] Comparative Example 2 did not involve sodium ion modification. In Example 2, the NaCl solution concentration was 0.1 mol / L; in Example 1, the NaCl solution concentration was 1 mol / L; and in Example 3, the NaCl solution concentration was 1.5 mol / L. As shown in the table above, the phosphate removal effect of the samples slightly decreased with increasing NaCl modification concentration, exhibiting a slight antagonistic effect. However, the ammonia nitrogen removal effect increased with increasing NaCl modification concentration. After reaching 1.0 mol / L, further increasing the NaCl concentration did not significantly improve the ammonia nitrogen removal effect. Considering economic factors, a 1.0 mol / L NaCl solution was the optimal choice for modification.

[0062] As can be seen from Example 1 and Comparative Example 3, the adsorbent material obtained by first modifying natural zeolite with zirconium and then with sodium has a better adsorption effect on ammonia nitrogen and phosphate than the adsorbent material obtained by first modifying with sodium and then with zirconium.

[0063] Finally, it should be noted that the above embodiments do not limit the present invention in any way. Those skilled in the art can make modifications and improvements based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. An application of a modified zeolite material in the simultaneous removal of ammonia nitrogen and phosphate from wastewater, characterized in that, The preparation method of the modified zeolite material includes the following steps: S1. Add natural zeolite and soluble zirconium salt to deionized water, mix evenly and shake. After shaking is complete, evaporate the deionized water, and then dry, wash and dry again to obtain zirconium-modified natural zeolite. S2. Add zirconium-modified natural zeolite to NaCl solution and mix evenly to obtain a solid-liquid mixture. Then, place the solid-liquid mixture in a water bath shaker for shaking treatment. After shaking is completed, take out the solid, wash and dry it to obtain the modified zeolite material. In step S1, the mass ratio of natural zeolite to soluble zirconium salt is 10:2-6.

2. The application according to claim 1, characterized in that, In step S1, the soluble zirconium salt is selected from ZrOCl2·8(H2O) or ZrO(NO3)2·2H2O.

3. The application according to claim 1, characterized in that, In step S1, the ratio of natural zeolite to deionized water is 1g:10-15mL.

4. The application according to claim 1, characterized in that, In step S1, the rotation speed of the shaking table during the oscillation process is 100-400 r / min, and the oscillation time is 18-36 h.

5. The application according to claim 1, characterized in that, In step S2, the ratio of zirconium-modified natural zeolite to NaCl solution is 1g:15-30mL.

6. The application according to claim 1, characterized in that, In step S2, the concentration of the NaCl solution is 0.1-1.5 mol / L.

7. The application according to claim 1, characterized in that, In step S2, the rotation speed of the oscillator is 100-300 r / min, and the oscillation time is 4-8 h.

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