Zinc ion modified zeolite, method for preparing the same, and use thereof

Abstract

The application provides a zinc ion modified zeolite and a preparation method and application thereof. 2+ The modification of the zeolite by the zinc ion can balance the negative charge on the zeolite, so that the modified zeolite has reduced electrostatic repulsion to anions and can have more groups capable of combining with phosphates, and thus has the ability to remove phosphates. 2+ In the process of dynamically adsorbing ammonia nitrogen and phosphates in simulated and actual wastewater in a transfer station, the Thomas model is used for fitting. 2+ The adsorption capacity of the modified zeolite to the simulated water reaches 4.49 mg NH3-N / g and 3.04 mg P / g, and the adsorption capacity of the modified zeolite to the actual water reaches 2.35 mg NH3-N / g and 3.63 mg P / g. 2+ The modified zeolite has good adsorption effect on nitrogen and phosphorus in the continuous flow treatment of the actual water.

Description

Technical Field

[0001] This invention relates to the field of wastewater denitrification and phosphorus removal technology, and in particular to a zinc ion modified zeolite, its preparation method, and its application. Background Technology

[0002] In recent years, due to the accelerated pace of urbanization and the improvement of people's living standards, the amount of urban domestic waste generated has been increasing year by year. Waste transfer stations are a crucial link in the waste transportation process, and the wastewater from these stations is a secondary pollutant generated during the transfer. Its composition is very complex, containing large amounts of organic pollutants, ammonia nitrogen, phosphates, heavy metals, and toxic and harmful pollutants. Most of the wastewater from transfer stations ultimately ends up in urban wastewater treatment plants. If discharged directly into the municipal pipe network without strict treatment, it will severely impact the urban wastewater treatment system. High concentrations of nitrogen and phosphorus pollutants in transfer station wastewater can seriously affect the stability of the main biological processes in wastewater treatment plants. Currently, wastewater from transfer stations is mostly treated using a combination of biological treatment and membrane technology. Biological treatment is easily affected by water quality fluctuations, resulting in effluent ammonia nitrogen and phosphate levels failing to meet effluent standards. Membrane technology suffers from membrane fouling and high costs, and it is ineffective in removing ammonia nitrogen. Therefore, researching emergency nitrogen and phosphorus treatment methods for waste transfer station wastewater to ensure stable effluent quality meets discharge standards is crucial.

[0003] Meanwhile, research on emergency nitrogen and phosphorus treatment technologies for wastewater will become a hot topic in the coming years, and the development of new materials for the simultaneous recovery of resources such as ammonia nitrogen and phosphate is of great significance. Adsorption methods are used for the removal of ammonia nitrogen and phosphate from water due to their advantages of fast reaction speed and high removal efficiency. However, traditional adsorbents have drawbacks such as low adsorption capacity, poor selectivity, and poor reusability, making it urgent to develop new and highly efficient adsorbents for the removal and recovery of ammonia nitrogen and phosphate.

[0004] Zeolites are structures formed by silicon and aluminum as the core, with oxygen atoms distributed around them, creating silicon-oxygen tetrahedra and aluminum-oxygen tetrahedra. These tetrahedra are connected by vertices and share an oxygen atom. The aluminum-oxygen tetrahedra are negatively charged. Due to these structural characteristics, zeolites often possess functions such as ion exchange, adsorption, and catalysis. The internal spatial structure of zeolites is network-like, with numerous channels and cavities accounting for 40%–50% of their total volume. Simultaneously, their specific surface area can reach 400–1000 m². 2 The large specific surface area ( / g) of zeolites provides numerous adsorption sites for the adsorption process. Due to their negatively charged structure, zeolites require K+. + Na + Ca 2+The zeolite neutralizes charges with cations, and when stronger cations are present in the external environment, they exchange out the cations originally bound inside the zeolite. After ion exchange, it can be repeatedly regenerated using different methods to restore its ion exchange capacity. Furthermore, zeolite can form electrostatic attraction around itself, exhibiting good adsorption of polar molecules. However, because the zeolite surface is negatively charged, it has almost no effect on phosphate removal. Therefore, to enable zeolite to simultaneously remove ammonia nitrogen and phosphate, it needs to be modified and regulated. On the one hand, its ability to remove ammonia nitrogen needs to be maintained or enhanced; on the other hand, it needs to acquire the ability to remove phosphate.

[0005] Given the current problems with zeolite, it is necessary to improve it. Summary of the Invention

[0006] In view of this, the present invention proposes a zinc ion modified zeolite, its preparation method and application, to solve or partially solve the technical problems existing in the prior art.

[0007] In a first aspect, the present invention provides a method for preparing zinc ion-modified zeolite, comprising the following steps:

[0008] Zeolite is immersed in a zinc salt solution, allowing the zinc salt to be loaded onto the zeolite. After standing, the solid and liquid are separated, and the solid is collected, washed, and dried to obtain zinc ion modified zeolite.

[0009] Preferably, in the method for preparing zinc ion modified zeolite, the zinc salt in the zinc salt solution includes at least one of zinc nitrate, zinc chloride, and zinc sulfate.

[0010] Preferably, the method for preparing zinc ion modified zeolite involves immersing the zeolite in a zinc salt solution to load the zinc salt onto the zeolite. The controlled process conditions are: loading time of 1–30 h, temperature of 20–30 °C, and oscillation speed of 100–120 r / min.

[0011] Preferably, in the method for preparing the zinc ion modified zeolite, the zeolite is 1-2 mm in size.

[0012] Preferably, in the method for preparing zinc ion modified zeolite, the mass fraction of the zinc salt solution is 1-20%.

[0013] The mass ratio of zinc salt to zeolite in the zinc salt solution is 1:(0.5-3).

[0014] Preferably, the method for preparing the zinc ion modified zeolite involves a standing time of 40–60 min, a drying temperature of 100–110 °C, and a drying time of 12–16 h.

[0015] Secondly, the present invention also provides a zinc ion modified zeolite, which is prepared by the preparation method described above.

[0016] Thirdly, the present invention also provides an application of the zinc ion modified zeolite prepared by the preparation method described above, or the zinc ion modified zeolite described above, as an adsorbent for the simultaneous adsorption of nitrogen and phosphorus.

[0017] Preferably, the application includes the following steps:

[0018] Zinc-modified zeolite was added as an adsorbent to a mixed solution containing ammonia nitrogen and phosphate, and the reaction was shaken to allow ammonia nitrogen and phosphate to be adsorbed simultaneously by the adsorbent.

[0019] Preferably, the application further includes:

[0020] The adsorbent that has adsorbed ammonia nitrogen and phosphate is separated from the mixed solution;

[0021] The adsorbent that has adsorbed ammonia nitrogen and phosphate is eluted with alkaline solution, causing ammonia nitrogen and phosphate to desorb from the adsorbent. After washing and drying, the adsorbent is regenerated and can be recycled for adsorbing ammonia nitrogen and phosphate again.

[0022] The method for preparing zinc ion-modified zeolite according to the present invention has the following advantages over the prior art:

[0023] 1. The zinc ion-modified zeolite prepared by this invention retains or enhances the original ammonia nitrogen removal capacity of artificial zeolite, through Zn 2+ Modification balances the negative charge on the zeolite, reducing its electrostatic repulsion to anions. It also potentially gains more groups that can bind with phosphates, thus enabling phosphate removal. Traditional zeolites, due to their negative surface charge, have almost no effect on phosphate removal. In practical applications, adsorbents need to adsorb and separate target pollutants from various interfering contaminants; therefore, the adsorbent must have high selectivity for pollutants. Zn 2+ The modified zeolite was used to fit the dynamic adsorption of ammonia nitrogen and phosphate in wastewater from a simulated and actual transfer station. The Zn... 2+ The modified zeolite exhibited adsorption capacities of 4.49 mg NH3-N / g and 3.04 mg P / g for simulated water, and 2.35 mg NH3-N / g and 3.63 mg P / g for actual water, demonstrating the superior adsorption capacity of Zn. 2+ Modified zeolite showed good adsorption effect on nitrogen and phosphorus in actual continuous water treatment.

[0024] 2. The Zn prepared by this invention 2+Modified zeolite has the ability to be recycled and reused. After being reused five times, its ammonia nitrogen adsorption capacity can still be maintained at 74% of the initial value, and its phosphate adsorption capacity can still be maintained at 62% of the initial value. This good renewability shows its potential for practical application and promotion. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a scanning electron microscope image of the zeolite (a) used in Example 1;

[0027] Figure 2 The Zn prepared in Example 1 2+ Scanning electron microscope image of modified zeolite (b);

[0028] Figure 3 The BET test chart is shown for the zeolite used in Example 1;

[0029] Figure 4 The Zn prepared in Example 1 2+ BET test results for modified zeolite;

[0030] Figure 5 The zeolite used in Example 1 and the Zn prepared in Example 1 2+ XRD pattern of modified zeolite;

[0031] Figure 6 The images show the simultaneous adsorption of ammonia nitrogen and phosphate by the zinc ion-modified zeolite prepared in Examples 1 and 2.

[0032] Figure 7 The images show the simultaneous adsorption of ammonia nitrogen and phosphate by the zinc ion-modified zeolites prepared in Examples 1 and 3.

[0033] Figure 8 The images show the simultaneous adsorption of ammonia nitrogen and phosphate by the zinc ion-modified zeolites prepared in Examples 1 and 4.

[0034] Figure 9 For the dosage of Zn 2+ Effects of modified zeolite on the simultaneous adsorption of ammonia nitrogen and phosphate: (a) removal rate; (b) adsorption capacity.

[0035] Figure 10 The effect of solution pH on Zn 2+The effect of modified zeolite on the simultaneous adsorption of ammonia nitrogen and phosphate;

[0036] Figure 11 The effect of coexisting cations on the simultaneous adsorption of ammonia nitrogen and phosphate: (a) adsorption effect of ammonia nitrogen; (b) adsorption effect of phosphate.

[0037] Figure 12 The effect of coexisting anions on the simultaneous adsorption of ammonia nitrogen and phosphate: (a) adsorption effect of ammonia nitrogen; (b) adsorption effect of phosphate.

[0038] Figure 13 Zn 2+ Pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic curves of simultaneous adsorption of ammonia nitrogen and phosphate by modified zeolite;

[0039] Figure 14 Zn 2+ Fitting curves of the internal diffusion model for the simultaneous adsorption of ammonia nitrogen and phosphate by modified zeolite;

[0040] Figure 15 Zn 2+ Adsorption isotherms of modified zeolite for simultaneous adsorption of ammonia nitrogen and phosphate;

[0041] Figure 16 Zn 2+ Removal rate after repeated regeneration of modified zeolite;

[0042] Figure 17 Zn 2+ The adsorption capacity of modified zeolite after repeated regeneration;

[0043] Figure 18 This is a schematic diagram of a dynamic experimental adsorption device;

[0044] Figure 19 Zn 2+ Dynamic adsorption effect of modified zeolite on effluent from the biological section of a simulated waste transfer station;

[0045] Figure 20 Zn 2+ The dynamic adsorption effect of modified zeolite on the effluent from the biological section of a real waste transfer station. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0047] To better understand the invention and not to limit its scope, all figures indicating amounts, percentages, and other numerical values ​​used in this application should, in all cases, be understood to be modified by the word "approximately." Therefore, unless specifically stated otherwise, the numerical parameters listed in the specification and appended claims are approximate values ​​and may vary depending on the desired properties being sought. Each numerical parameter should at least be considered as obtained based on reported significant figures and through conventional rounding methods.

[0048] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0049] This application provides a method for preparing zinc ion-modified zeolite, comprising the following steps:

[0050] Zeolite is immersed in a zinc salt solution, allowing the zinc salt to be loaded onto the zeolite. After standing, the solid and liquid are separated, and the solid is collected, washed, and dried to obtain zinc ion modified zeolite.

[0051] Zn prepared by this invention 2+ Modified zeolite materials retain or enhance the original ammonia nitrogen removal capacity of synthetic zeolites through Zn 2+ The modification balances the negative charge on the zeolite, reducing its electrostatic repulsion of anions. It may also gain more groups that can combine with phosphates, thus enabling it to remove phosphates. In contrast, traditional zeolites, due to their negative surface charge, have almost no effect on removing phosphates.

[0052] In some embodiments, the zinc salt in the zinc salt solution includes at least one of zinc nitrate, zinc chloride, and zinc sulfate.

[0053] In some embodiments, zeolite is immersed in a zinc salt solution to load the zinc salt onto the zeolite. The controlled process conditions are: loading time of 1 to 30 hours, temperature of 20 to 30°C, and oscillation speed of 100 to 120 r / min.

[0054] Specifically, in the above embodiments, zeolite was added to the zinc salt solution and loaded in a water bath shaker: the loading time was 1 to 30 hours, the temperature was 20 to 30 degrees Celsius, and the shaking speed was 100 to 120 r / min.

[0055] In some embodiments, the zeolite is 1-2 mm in size.

[0056] In some embodiments, the zinc salt solution has a mass fraction of 1–20%.

[0057] In some embodiments, the mass ratio of zinc salt to zeolite in the zinc salt solution is 1:(0.5-3).

[0058] In some embodiments, the standing time is 40–60 min, the drying temperature is 100–110 °C, and the drying time is 12–16 h.

[0059] In some embodiments, zeolite is immersed in a zinc salt solution to load the zinc salt onto the zeolite. After standing, solid-liquid separation is performed, and the solid is collected. After washing until the pH of the effluent is neutral, it is dried to obtain zinc ion modified zeolite.

[0060] Based on the same inventive concept, the present invention also provides a zinc ion modified zeolite, which is prepared by the above-described preparation method.

[0061] Based on the same inventive concept, the present invention also provides an application of the zinc ion modified zeolite prepared by the above preparation method or the above zinc ion modified zeolite as an adsorbent for simultaneous adsorption of nitrogen and phosphorus.

[0062] Specifically, the above application includes the following steps:

[0063] Zinc-modified zeolite was added as an adsorbent to a mixed solution containing ammonia nitrogen and phosphate, and the reaction was shaken to allow ammonia nitrogen and phosphate to be adsorbed simultaneously by the adsorbent.

[0064] In some embodiments, during the oscillation reaction step, the oscillation speed is 140-180 r / min, and the oscillation reaction time is 2-24 h.

[0065] In the above embodiments, the mixed solution containing ammonia nitrogen and phosphate may also contain interfering ions in addition to ammonia nitrogen and phosphate, with the interfering ion being Na+. + K + Mg 2+ Ca 2+ Cl - SO4 2- HCO3 - and NO3 - At least one of them.

[0066] The Zn2+ modified zeolite prepared by this invention has recyclable properties. After five reuses, the ammonia nitrogen adsorption capacity can still be maintained at 74% of the initial value, and the phosphate adsorption capacity can still be maintained at 62% of the initial value. This good recyclability shows the potential for practical application and promotion.

[0067] In some embodiments, the above-described applications further include:

[0068] The adsorbent that has adsorbed ammonia nitrogen and phosphate is separated from the mixed solution by means of filtration or centrifugation;

[0069] The adsorbent that has adsorbed ammonia nitrogen and phosphate is eluted with alkaline solution, causing ammonia nitrogen and phosphate to desorb from the adsorbent. After washing and drying, the adsorbent is regenerated and can be recycled for adsorbing ammonia nitrogen and phosphate again.

[0070] The following specific embodiments further illustrate the zinc ion-modified zeolite of this application, its preparation method, and its application. This section further illustrates the content of the present invention in conjunction with specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0071] The zeolite used in the following examples has a particle size of 1-2 mm and the chemical formula is (SiO2). x (Al2O3) y Purchased from BKMAN Bio.

[0072] Example 1

[0073] This application provides a method for preparing zinc ion-modified zeolite, comprising the following steps:

[0074] S1. Wash and dry 10g of zeolite; prepare 100mL of Zn(NO3)2·6H2O solution with a mass fraction of 10%;

[0075] S2. Mix 10g of zeolite with 100mL of Zn(NO3)2·6H2O solution (Zn(NO3)2 to zeolite mass ratio 1:1) in a 250mL beaker. Incubate the mixture in a 25℃ water bath at 120rpm for 18 hours. After standing for a period, perform solid-liquid separation. Wash the solution multiple times with deionized water until the pH of the effluent is neutral. Dry the solution at 105℃ and collect the Zn. 2+ Modified zeolite materials.

[0076] Tested: Zn 2+ The modified zeolite has an average pore size of 8.21 nm.

[0077] Figure 1 This is a scanning electron microscope image of the zeolite (a) used in Example 1. Figure 2 The Zn prepared in Example 1 2+ Scanning electron microscope image of modified zeolite (b).

[0078] from Figures 1-2 As can be seen from the above, the zeolite used in Example 1 and the Zn prepared in Example 1 are different. 2+ The modified zeolites, both exhibiting similar morphologies and numerous irregular shapes, have relatively few and large pores, indicating that Zn... 2+ Modified zeolites primarily involve zinc entering the pores of the zeolite through ion exchange and existing within its channels, thus their external morphology remains largely unchanged.

[0079] Figure 3 The BET test result is shown for the zeolite used in Example 1. Figure 4 The Zn prepared in Example 1 2+ BET test results for modified zeolite.

[0080] from Figures 3-4 As can be seen from the above, the zeolite used in Example 1 and the Zn prepared in Example 1 are different. 2+ Modified zeolites, both materials are mainly mesoporous, with the average pore size of the synthetic zeolite being 14.02 nm. Zn 2+ The modified zeolite has an average pore size of 8.21 nm, and Zn 2+ The specific surface area, pore area, and average pore size of the modified zeolite are all reduced, which is due to the decrease in Zn. 2+ The formation of complexes through exchange reduces the pore volume.

[0081] Figure 5 The zeolite used in Example 1 ( Figure 5 The original zeolite and the Zn prepared in Example 1 2+ Modified zeolite ( Figure 5 Chinese Zn 2+ XRD pattern of zeolite.

[0082] from Figure 5 As can be seen from the figure, distinct diffraction peaks appear at diffraction angles 2θ of 12.6°, 16.3°, 21.9°, 24.3°, 27.5°, 30.3°, and 34.6°, which coincide with the characteristic peaks of clinoptilolite. The figure also shows that the original synthetic zeolite and the modified zeolite maintain similar characteristic diffraction peaks, with no new characteristic diffraction peaks appearing. This indicates that the modification using Zn... 2+ The modification did not significantly alter the original structure of the synthetic zeolite.

[0083] Example 2

[0084] This embodiment provides a method for preparing zinc ion modified zeolite, which is the same as in embodiment 1, except that the loading time in step S2 is 1h, 3h, 5h, 8h, 12h, 24h and 30h respectively, and the remaining process steps are the same as in embodiment 1.

[0085] Example 3

[0086] This embodiment provides a method for preparing zinc ion modified zeolite, similar to Embodiment 1, except that the mass fraction of the Zn(NO3)2·6H2O solution in step S1 (i.e., Zn 2+ The concentrations were 1%, 2%, 5%, 15%, and 20%, respectively, and the remaining process steps were the same as in Example 1.

[0087] Example 4

[0088] This embodiment provides a method for preparing zinc ion modified zeolite, which is the same as in Example 1, except that the mass ratio of zinc nitrate to zeolite is 1:0.5, 1:2 and 1:3 respectively, and the remaining process steps are the same as in Example 1.

[0089] The zinc ion-modified zeolites prepared in Examples 1-4 were tested for their simultaneous adsorption effects on ammonia nitrogen and phosphate. Figures 6-8 As shown. Figure 6 The images show the simultaneous adsorption of ammonia nitrogen and phosphate by the zinc ion-modified zeolite prepared in Examples 1 and 2. Figure 7 The images show the simultaneous adsorption of ammonia nitrogen and phosphate by the zinc ion-modified zeolites prepared in Examples 1 and 3. Figure 8 The images show the simultaneous adsorption of ammonia nitrogen and phosphate by the zinc ion-modified zeolite prepared in Examples 1 and 4.

[0090] Specifically, the nitrogen and phosphorus simultaneous adsorption test method is as follows: a mixed solution with ammonia nitrogen and phosphate concentration of 50 mg / L was prepared using NH4Cl and KH2PO4. The pH was adjusted to 7. 50 ml of the mixed solution was placed in a serum bottle, and adsorbent (i.e., zinc ion modified zeolite prepared in different examples) was added. The solution was shaken in a constant temperature shaking oven at 25°C and 140 rpm for 24 h. After the reaction was completed, the concentrations of ammonia nitrogen and phosphate were measured. In Examples 1 and 2, the amount of adsorbent added was 1.2 g; in Example 3, the amount of adsorbent added was 1.05 g; and in Example 4, the amount of adsorbent added was 1.1 g.

[0091] from Figure 6 It can be seen from this that Zn 2+The modified zeolite showed an increased phosphate removal rate from 56.8% to 93.9% between 1 and 18 hours, but no significant improvement was observed after 30 hours. Its adsorption efficiency for ammonia nitrogen remained relatively stable, consistently between 77.2% and 81.6%. Experimental analysis revealed that during simultaneous adsorption, Zn... 2+ Modified zeolite exhibits significantly higher adsorption efficiency for phosphates than zeolite alone. This is likely due to the presence of ammonia nitrogen, which neutralizes the negative charge on the modified zeolite surface, allowing for better adsorption of phosphate ions. In summary, this indicates that Zn... 2+ Sufficient loading time is required to load the zeolite from the reaction solution; too short a loading time can easily lead to incomplete loading or Zn. 2+ The distribution of phosphates is uneven, but excessively long loading times increase the cost of material preparation. Considering that increasing the loading time significantly improves the phosphate removal rate, a loading time of 18 hours was selected in subsequent preparations.

[0092] from Figure 7 The results show that as the zinc concentration increased from 1% to 20%, the phosphate removal rate increased from 48.3% to 79.6%. The removal rate did not change significantly when the zinc concentration increased from 10% to 20%, which may be due to the limited number of binding sites in the zeolite itself, and excessively high Zn concentrations... 2+ Concentration did not significantly increase its loading. As can be seen from the figure, as the zinc loading concentration gradually increases, Zn... 2+ The adsorption efficiency of modified zeolite for ammonia nitrogen showed little change, decreasing from 85.5% to 79.9%, which is close to the adsorption efficiency of the modified zeolite alone. This may be due to the presence of Zn. 2+ Increased concentration causes blockage of the pores on the surface of the zeolite, reducing the zeolite's ability to adsorb ammonia nitrogen.

[0093] from Figure 8 As can be seen, with the decrease in the zinc / zeolite mass ratio, the adsorption efficiency of zeolite for phosphate decreased from 82.3% to 66.1%; overall, the simultaneous adsorption of Zn... 2+ Modified zeolite exhibits stronger adsorption effects on ammonia nitrogen and phosphate than it does on adsorption alone.

[0094] Application Example 1

[0095] A mixed solution with initial ammonia nitrogen and phosphate concentrations of 50 mg / L was prepared using NH4Cl and KH2PO4. 50 ml of this mixed solution was transferred to a serum bottle, and the pH was adjusted to 7. Zn was then added at concentrations of 4 g / L, 8 g / L, 12 g / L, 16 g / L, 20 g / L, 24 g / L, and 30 g / L, respectively. 2+ Modified zeolite was shaken in a constant temperature shaking chamber at 25℃ and 140 rpm for 24 hours. After the reaction, the concentrations of ammonia nitrogen and phosphate were measured. Zn... 2+The preparation method of the modified zeolite is the same as in Example 1, except that the loading time is 16 hours.

[0096] like Figure 9 As shown, Zn 2+ The removal rate of ammonia nitrogen by modified zeolite increased steadily, with an adsorption capacity of 1.51–4.29 mg / g; Zn 2+ The removal rate of phosphate by modified zeolite has steadily increased, reaching a maximum of 91.75%.

[0097] Application Example 2

[0098] A mixed solution with initial ammonia nitrogen and phosphate concentrations of 50 mg / L was prepared using NH4Cl and KH2PO4. 50 ml of this mixed solution was placed in a serum bottle, and the Zn prepared in Example 1 was added. 2+ Modified zeolite, Zn 2+ The modified zeolite was added at a dosage of 24 g / L. The pH value was adjusted to 3-11 with NaOH and HCl. The mixture was shaken in a constant temperature shaking box at 25℃ and 140 rpm for 24 h. After the reaction was completed, the concentrations of ammonia nitrogen and phosphate and the pH of the solution were measured.

[0099] like Figure 10 As shown, the pH range of 2-12 has little effect on the removal rate of ammonia nitrogen; pH changes do not cause significant fluctuations in ammonia nitrogen adsorption. 2+ Modified zeolite has a significant impact on the adsorption effect of phosphate in the pH range of 2-12.

[0100] Application Example 3

[0101] A mixed solution with initial ammonia nitrogen and phosphate concentrations of 50 mg / L was prepared using NH4Cl and KH2PO4, and then 0, 5, and 10 mM Na were added respectively. + Ca 2+ K + Mg 2+ NO3 - Cl - SO4 2- HCO3 - Adjust the pH to 7, take 50 ml of the mixed solution into a serum bottle, and add the Zn prepared in Example 1. 2+ Modified zeolite, Zn 2+ The modified zeolite was added at a dosage of 22 g / L, and the mixture was shaken in a constant temperature shaking box at 25℃ and 140 rpm for 24 h. After the reaction was completed, the concentrations of ammonia nitrogen and phosphate were measured.

[0102] Figure 11 The effect of coexisting cations on the simultaneous adsorption of ammonia nitrogen and phosphate: (a) adsorption effect of ammonia nitrogen; (b) adsorption effect of phosphate.

[0103] Figure 12 The effect of coexisting anions on the simultaneous adsorption of ammonia nitrogen and phosphate: (a) adsorption effect of ammonia nitrogen; (b) adsorption effect of phosphate.

[0104] like Figure 11 As shown, in the presence of competing cations, Zn 2+ The modified zeolites showed a slight improvement in the adsorption efficiency of phosphates, while their adsorption efficiency for ammonia nitrogen decreased. Figure 12 As shown, in the presence of competing anions, Zn 2+ The adsorption efficiency of modified zeolites for ammonia nitrogen decreased slightly. However, their adsorption efficiency for phosphates showed a different pattern, except for HCO3. - All other anions have a promoting effect.

[0105] Application Example 4

[0106] Weigh 12g of adsorbent (Zn prepared in Example 1) 2+ Modified zeolite was added to 500 mL of a mixed solution of ammonia nitrogen and phosphate, both initially at a concentration of 50 mg / L (prepared using NH4Cl and KH2PO4), with a pH of 7. The solution was shaken in a constant-temperature shaking incubator at 25°C and 140 rpm for 24 hours. Samples were taken at intervals to determine the concentrations of ammonia nitrogen and phosphate. Figure 13 As shown, PFO(NH3-N), PSO(NH3-N), PFO(P), and PSO(P) are the pseudo-first-order and pseudo-second-order kinetic curves of ammonia nitrogen and phosphate, respectively. Zn 2+ The modified zeolite reaches equilibrium for ammonia nitrogen adsorption in approximately 9 hours, and for phosphate adsorption in approximately 24 hours. (Zn) 2+ The modified zeolite exhibits predominantly chemisorption for ammonia nitrogen and phosphate, with a significantly greater effect on ammonia nitrogen adsorption than on phosphate adsorption. An internal diffusion model was used for fitting the data, such as... Figure 14 As shown, this illustrates Zn 2+ The process of simultaneous adsorption of ammonia nitrogen and phosphate by modified zeolite is jointly controlled by liquid film diffusion and intraparticle diffusion.

[0107] Application Example 5

[0108] Prepare 500 mL of a mixed solution with an initial ammonia nitrogen concentration of 50 mg / L and phosphate concentrations ranging from 0 to 500 mg / L using NH4Cl and KH2PO4. Take 50 mL of this mixed solution into a serum bottle and weigh 1.2 g of the adsorbent (Zn prepared in Example 1). 2+Modified zeolite was subjected to isothermal adsorption for 24 h, and the phosphate content after adsorption was measured. Similarly, phosphate concentrations of 50 mg / L and ammonia nitrogen concentrations of 0–500 mg / L were subjected to isothermal adsorption for 24 h, and the ammonia nitrogen content after adsorption was measured. The data were fitted using Langmuir and Freundlich isotherm models, such as... Figure 15 As shown, this illustrates the effect of Zn at 25℃. 2+ The adsorption of ammonia nitrogen and phosphate by modified zeolite occurs through a combination of chemical and physical adsorption. The Langmuir model shows that the maximum adsorption capacities for ammonia nitrogen and phosphate during simultaneous adsorption are 19.74 mg / g and 26.28 mg / g, respectively. Fitting the data with the Freundlich model reveals that Zn... 2+ Modified zeolite exhibits better adsorption of ammonia nitrogen than phosphate, and both adsorption processes are relatively easy to perform.

[0109] Application Example 6

[0110] Take 12g of adsorbent (Zn prepared in Example 1) 2+ Modified zeolite was added to 500 mL of a mixed solution with an initial concentration of 50 mg / L for both ammonia nitrogen and phosphate (prepared using NH4Cl and KH2PO4) and a pH of 7. The solution was shaken for 24 hours at 25°C and 140 rpm. After the reaction, the concentrations of ammonia nitrogen and phosphate were measured. The adsorbent was recovered by washing and drying. Ammonia nitrogen and phosphate were then desorbed from the adsorbent using 0.1 M NaOH solution. The desorbed adsorbent was washed with deionized water until neutral, dried in a 105°C oven, and collected. This regeneration process was repeated five times. Figure 16 and Figure 17 As shown, after five desorption and regeneration cycles, Zn 2+ The adsorption capacity of the modified zeolite decreased from 1.76 mg NH3-N / g and 1.69 mg P / g to 1.30 mg NH3-N / g and 1.05 mg P / g, with the ammonia nitrogen adsorption capacity remaining at 74% and the phosphate adsorption capacity remaining at 62%.

[0111] Application Example 7

[0112] Dynamic Adsorption Experiment

[0113] The dynamic experimental setup consists of a storage tank, a peristaltic pump, a packed column, a collection tank, and matching tubing. The packed column is a 30cm long, 2.6cm inner diameter glassy column, supported at the bottom by glass wool and filled with adsorbent material at the top to a height of 4cm. After filling, deionized water is used for initial influent simulation until the column is completely filled. Simultaneously, the actual outflow rate is measured periodically and calibrated by adjusting the peristaltic pump. The influent direction is from bottom to top. Once the flow rate stabilizes at the preset value of 2.75ml / min, the formal experiment begins. The experimental setup is as follows: Figure 18 As shown. The influent was at an ambient temperature of 15℃ and a pH of 7. One set each of actual and simulated water were used for the biological treatment of landfill leachate effluent. The simulated water was prepared based on the quality of the actual water. The breakthrough time and breakthrough curve characteristics of the adsorption column were investigated for both actual and simulated water at fixed flow rates and bed heights. Figure 19 and Figure 20 As shown, Zn 2+ Modified zeolite exhibited good adsorption performance in dynamic adsorption. In simulated water quality, the dynamic adsorption capacities for ammonia nitrogen and phosphate reached 4.84 mg / g and 2.58 mg / g, respectively, while in actual water quality, the two indicators reached 2.55 mg / g and 2.73 mg / g, respectively.

[0114] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An application of zinc ion-modified zeolite as an adsorbent for the simultaneous adsorption of nitrogen and phosphorus; the application includes the following steps: Zinc ion-modified zeolite was added as an adsorbent to a mixed solution containing ammonia nitrogen and phosphate, and the reaction was shaken so that ammonia nitrogen and phosphate were simultaneously adsorbed by the adsorbent. The preparation method of the zinc ion modified zeolite includes the following steps: Zeolite is immersed in a zinc salt solution, so that the zinc salt is loaded on the zeolite. After standing, the solid and liquid are separated, the solid is collected, washed, and dried to obtain zinc ion modified zeolite. The zinc salt in the zinc salt solution includes at least one of zinc nitrate, zinc chloride, and zinc sulfate. Zeolite was impregnated in a zinc salt solution to load the zinc salt onto the zeolite. The controlled process conditions were: loading time of 18 h, temperature of 20–30 °C, and oscillation speed of 100–120 r / min. The particle size of the zeolite is 1-2 mm; The zinc salt solution has a mass fraction of 10%. The mass ratio of zinc salt to zeolite in the zinc salt solution is 1:

1.

2. The application as described in claim 1, characterized in that, Also includes: The adsorbent that has adsorbed ammonia nitrogen and phosphate is separated from the mixed solution; The adsorbent that has adsorbed ammonia nitrogen and phosphate is eluted with alkaline solution, causing ammonia nitrogen and phosphate to desorb from the adsorbent. After washing and drying, the adsorbent is regenerated and can be recycled for adsorbing ammonia nitrogen and phosphate again.

3. The application as described in claim 1, characterized in that, The standing time is 40-60 minutes, the drying temperature is 100-110℃, and the drying time is 12-16 hours.

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