Phosphorus-removing and bacteriostatic modified zeolite filler, and preparation method and application thereof

Abstract

The application discloses a phosphorus-removing and bacterium-inhibiting modified zeolite filler and a preparation method and application thereof, and relates to the technical field of fillers, in particular to a preparation method of the phosphorus-removing and bacterium-inhibiting modified zeolite filler. The preparation method comprises the following steps: dissolving chitosan in acetic acid, stirring and uniformly dissolving, then adding dimethyl diallyl ammonium chloride solution, uniformly mixing, and then carrying out heating reaction; after the reaction is completed, cooling to room temperature, then adding acetone to generate a precipitate, washing, drying, and then grinding into powder to obtain quaternary ammonium chitosan; mixing natural zeolite, quaternary ammonium chitosan and water, uniformly stirring, then dropping into sodium hydroxide solution, washing, drying, and then obtaining chitosan-zeolite composite material; uniformly stirring the chitosan-zeolite composite material and lanthanum nitrate hexahydrate, adjusting pH to 11-14, stirring, washing, drying, and then obtaining lanthanum-chitosan-zeolite composite material; mixing the lanthanum-chitosan-zeolite composite material and cement, granulating, air-drying, steam curing, and drying. The filler obtained by the application has the advantages of non-toxicity, strong adsorption performance, good stability and the like.

Description

Technical Field

[0001] This invention relates to packing materials, their preparation methods, and applications, specifically a phosphorus-removing and antibacterial modified zeolite packing material, its preparation method, and its applications. Background Technology

[0002] Phosphorus is an essential nutrient for aquatic organisms such as algae, and excessive phosphorus levels in water bodies lead to eutrophication. Eutrophication causes irreversible problems such as biodiversity degradation, water quality deterioration, and changes in the composition and dominance of invasive species. Currently, phosphorus removal methods include chemical precipitation and activated sludge processes. These traditional treatment technologies can effectively remove phosphorus and meet discharge standards, but achieving deep phosphorus removal requires the addition of large amounts of chemical agents, resulting in high costs. Therefore, there is an urgent need for a low-cost, high-efficiency, and pollution-free technology to remove phosphorus from water bodies.

[0003] Constructed wetlands (CWs) are a promising ecological water treatment technology. Due to their low cost, ease of operation, and landscape potential, they have been widely used in recent years for the deep removal of phosphorus from wastewater or aquatic environments. Phosphorus removal in constructed wetlands is primarily achieved through the synergistic effect of the substrate, plants, and microorganisms. The substrate plays a dominant role, but traditional substrates such as sand, gravel, and natural zeolite, intended to support the growth of constructed wetland plants, typically lack phosphorus removal capabilities or have weak phosphorus removal capacity. Furthermore, the tendency for substrates to clog, leading to short lifespans, remains a problem, limiting the application of constructed wetlands in treating slightly polluted water bodies.

[0004] The basic structure of natural zeolite consists of silicon-oxygen tetrahedra and aluminum-oxygen tetrahedra, with the aluminum-oxygen tetrahedra carrying a negative charge. However, the adsorption effect of natural zeolite on phosphorus is not ideal. To improve its treatment performance, natural zeolite is usually modified. Currently, most research on the modification of natural zeolite and its denitrification and phosphorus removal performance focuses on enhancing its ammonia nitrogen removal capacity. For phosphate adsorption, rare earth modification, represented by lanthanum hydroxide, has been a widely studied modification technique in recent years, achieving removal even at low phosphorus concentrations. However, rare earth modification of natural zeolite alone does not have a significant antibacterial effect, and it cannot simultaneously remove phosphorus and inhibit bacteria, thus failing to alleviate biological blockage in constructed wetlands. Summary of the Invention

[0005] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a simple and convenient method for preparing phosphorus removal and antibacterial modified zeolite packing. Another purpose of this invention is to provide a phosphorus removal and antibacterial modified zeolite packing with fast adsorption, large adsorption capacity and good phosphorus removal and antibacterial effect. A further purpose of this invention is to provide an application of phosphorus removal and antibacterial modified zeolite packing in phosphorus adsorption and antibacterial treatment in constructed wetlands.

[0006] Technical solution: The preparation method of the phosphorus removal and antibacterial modified zeolite packing material of the present invention includes the following steps:

[0007] Step 1: Dissolve chitosan in acetic acid, stir and mix until dissolved, then add dimethyl diallyl ammonium chloride solution, mix evenly and heat to react. After the reaction is complete, cool to room temperature, then add acetone to form a precipitate, wash, dry and grind into powder to obtain quaternized chitosan.

[0008] Step 2: First, mix natural zeolite with quaternized chitosan and water, stir until homogeneous, then add it dropwise to a sodium hydroxide solution, wash and dry, then mix it with quaternized chitosan hexahydrate until homogeneous, adjust the pH to 11-14, stir, wash and dry; or first, mix natural zeolite with quaternized chitosan hexahydrate until homogeneous, adjust the pH to 11-14, stir, wash and dry, then mix it with quaternized chitosan and water, stir until homogeneous, then add it dropwise to a sodium hydroxide solution, wash and dry, to obtain a lanthanum-chitosan-zeolite composite material;

[0009] Step 3: Mix the lanthanum-chitosan-zeolite composite material with cement, granulate, air-dry, steam-cur, and dry to obtain phosphorus-removing and antibacterial modified zeolite filler.

[0010] Further, in step one, the mass ratio of chitosan, acetic acid, and dimethyl diallyl ammonium chloride solution is 4:1:1-2. The volume percentage of dimethyl diallyl ammonium chloride in the dimethyl diallyl ammonium chloride solution is 20-25 vol%. The heating temperature is 50-60℃, and the reaction time is 20-30 min.

[0011] Furthermore, in step two, the mass ratio of natural zeolite to quaternized chitosan is 3:0.5–1. The concentration of lanthanum nitrate hexahydrate is 0.1–0.5 mol / L.

[0012] Preferably, in step two, the natural zeolite is first stirred and mixed evenly with lanthanum nitrate hexahydrate, the pH is adjusted to 11-14, stirred, washed and dried, and then mixed with quaternized chitosan and water, stirred evenly, and then dropped into sodium hydroxide solution, washed and dried to obtain a lanthanum-chitosan-zeolite composite material with better antibacterial effect.

[0013] Furthermore, in step three, the mass ratio of the lanthanum-chitosan-zeolite composite material to cement is 2 to 8:1.

[0014] Furthermore, the washing and drying temperature is 50–60°C.

[0015] The phosphorus-removing and antibacterial modified zeolite packing obtained by the preparation method of the phosphorus-removing and antibacterial modified zeolite packing of the present invention.

[0016] The application of the phosphorus removal and antibacterial modified zeolite packing material described in this invention in phosphorus removal adsorption and antibacterial activity in constructed wetlands.

[0017] Furthermore, the application specifically includes the following steps: adding the phosphorus-removing and antibacterial modified zeolite filler to a phosphate-containing solution and fully saturating it for adsorption in a 25°C water bath shaker.

[0018] Preparation Principle: Chitosan is a biodegradable and non-toxic biopolymer material with low cost and broad-spectrum antibacterial properties. It also possesses active functional groups. The introduction of quaternary ammonium groups not only enhances chitosan's phosphorus removal ability but also strengthens its antibacterial effect. Quaternized chitosan and metal ions are chelated and co-loaded on the zeolite surface. The positively charged metal ions and functional groups can interact with the negatively charged bacterial membrane through electrostatic interactions, thereby interfering with the normal physiological functions of bacteria and leading to bacterial death.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0020] 1. The obtained packing material has the advantages of being non-toxic, having strong adsorption capacity and good stability. In particular, the packing material has antibacterial effect, which can not only alleviate the problem of short packing saturation time caused by matrix blockage, but also efficiently adsorb phosphorus in micro-pollutants.

[0021] 2. Adsorption and phosphorus removal experiments were conducted under low concentration conditions. The experimental results showed that the phosphorus removal material had a removal efficiency of more than 95% when the initial phosphorus concentration was 2 mg / L. It can be applied to the removal of phosphorus in slightly polluted water bodies. The preparation process of this invention is simple, and the prepared material has fast adsorption and large adsorption capacity. Attached Figure Description

[0022] Figure 1 This refers to the adsorption capacity of the materials prepared in Example 1, Comparative Example 1, and Comparative Example 2 for a phosphate concentration of 100 mg / L.

[0023] Figure 2 The adsorption and removal rates of the materials prepared in Example 1, Comparative Example 1, and Comparative Example 2 for a phosphate concentration of 2 mg / L are shown.

[0024] Figure 3 Example 1: Growth of bacteria on the surface of the material prepared in Comparative Example 1 on a plate, wherein a) Control group of Comparative Example 1, b) Control group of Example 1, c) Treatment group of Example 1, d) Treatment group of Comparative Example 1;

[0025] Figure 4 These are breakthrough curves at different initial phosphate concentrations;

[0026] Figure 5This is a comparison of the antibacterial effects of the materials prepared in Example 2, Comparative Example 1, Comparative Example 2, and Comparative Example 3 (0: Antibacterial zone of the material prepared in Comparative Example 1, 1: Antibacterial zone of the material prepared in Example 2, 2: Antibacterial zone of the material prepared in Comparative Example 3, 3: Antibacterial zone of the material prepared in Comparative Example 2).

[0027] Figure 6 This is an adsorption diagram of the materials prepared in Examples 1, 2, 1, 2, and 3 for a phosphate concentration of 2 mg / L. Detailed Implementation

[0028] Example 1

[0029] A method for preparing a phosphorus-removing and antibacterial modified zeolite filler includes the following steps:

[0030] (1) Rinse the natural zeolite three times with distilled water, then soak it in distilled water for 24 hours, changing the water every 4 hours to dissolve the impurities. Dry it in a drying oven at 60°C for 12 hours. Crush the dried zeolite and put it into a container for later use.

[0031] (2) Dissolve 1 g of chitosan in 50 mL of 5 vol% acetic acid and stir until dissolved. Slowly add 25 mL of 20 vol% dimethyl diallyl ammonium chloride solution and mix thoroughly. Immediately place the conical flask in a 55°C constant temperature magnetic stirrer and heat for 20 min. After the reaction is complete, cool to room temperature.

[0032] (3) Add an equal volume of acetone to the reaction system of step (2) in a fume hood to generate a large amount of white flocculent matter. After centrifugation, wash three times with anhydrous ethanol. Finally, put the product into a drying oven at 60°C and dry for 24 hours. Take it out and grind it to obtain a slightly yellow powder of quaternized chitosan.

[0033] (4) Dissolve the quaternized chitosan in water to form a quaternized chitosan solution of 10 g / L. Add 3 g of zeolite to 50 mL of the quaternized chitosan solution and stir on a magnetic stirrer for 4 h.

[0034] (5) Add the solution obtained in step (4) dropwise into a 1 mol / L NaOH solution. Then, wash the chitosan-zeolite composite with deionized water until the pH is constant, and dry it in an oven at 60°C to obtain the chitosan-zeolite composite material.

[0035] (6) Add 3g of chitosan-zeolite composite material to 50mL of 0.1mol / L (La(NO)3)3·6H2O solution and stir until homogeneous. Adjust the pH to 11 and stir at room temperature for 24h. After the reaction is complete, rinse the composite modified material with deionized water and then dry it in an oven at 60℃ for 24h to obtain lanthanum-chitosan-zeolite composite material.

[0036] (7) The lanthanum-chitosan-zeolite composite material was mixed with cement at a mass ratio of 2:1 and granulated to form spherical particles of 4-5 mm. The particles were air-dried for 24 hours and steam-cured for 2 hours. After drying, the phosphorus-removing and antibacterial modified zeolite filler was obtained.

[0037] Comparative Example 1

[0038] The natural zeolite was rinsed three times with distilled water, then soaked in distilled water for 24 hours, with the water changed every 4 hours to dissolve the impurities. After that, it was dried in a drying oven at 60°C for 12 hours. The dried zeolite was then crushed and placed in a container for later use.

[0039] Comparative Example 2

[0040] A method for preparing a chitosan-zeolite composite material includes the following steps:

[0041] (1) Rinse the natural zeolite three times with distilled water, then soak it in distilled water for 24 hours, changing the water every 4 hours to dissolve the impurities. Dry it in a drying oven at 60°C for 12 hours. Crush the dried zeolite and put it into a container for later use.

[0042] (2) Dissolve 1 g of chitosan in 50 mL of 5% acetic acid and stir until dissolved. Slowly add 25 mL of 20% dimethyl diallyl ammonium chloride solution and mix thoroughly. Immediately place the conical flask in a 55°C constant temperature magnetic stirrer and heat for 20 min. After the reaction is complete, cool to room temperature.

[0043] (3) Add an equal volume of acetone to the reaction system of step (2) in a fume hood to generate a large amount of white flocculent matter. After centrifugation, wash three times with anhydrous ethanol. Finally, put the product into a drying oven at 60°C and dry for 24 hours. Take it out and grind it to obtain a slightly yellow powder of quaternized chitosan.

[0044] (4) Add 3g of zeolite to 50mL of 10g / L quaternized chitosan solution obtained in step (3) and keep stirring on a magnetic stirrer for 4h.

[0045] (5) Add the solution obtained in step (4) dropwise into a 1 mol / L NaOH solution. Then, wash the chitosan-zeolite composite with deionized water until the pH is constant, and dry it in an oven at 60°C to obtain the chitosan-zeolite composite material.

[0046] Application Example 1

[0047] Adsorption and removal of phosphates from water:

[0048] Add 100 mL of phosphorus-containing solutions with concentrations of 2 mg / L and 100 mg / L to a 150 mL Erlenmeyer flask. Adjust the pH of the solution to 7 with dilute hydrochloric acid (0.1 mol / L) and sodium hydroxide solution (1 mol / L). Add 100 mg of the material prepared in Example 1, Comparative Example 1, and Comparative Example 2. Seal the flask with plastic wrap and place it in a constant temperature shaker. React for 24 h. After the reaction is complete, remove the flask and let it stand for 5 min. Use a 5 mL syringe to collect the supernatant of the phosphate solution and filter it using a 0.45 μm aqueous filter. Determine the concentration of the remaining phosphate using ammonium molybdate spectrophotometry.

[0049] The adsorption capacity of phosphate by the phosphorus-removing and antibacterial modified zeolite packing material prepared in Example 1 and the original natural zeolite material prepared in Comparative Example 1 as adsorbents was calculated. Figure 1 As shown, calculations show that the phosphorus-removing and antibacterial modified zeolite filler prepared in Example 1 has an adsorption capacity of 46.69 mg / g for phosphate ions, while the original natural zeolite material prepared in Comparative Example 1 has an adsorption capacity of 2.89 mg / g for phosphate ions, and the chitosan-modified zeolite prepared in Comparative Example 2 has an adsorption capacity of 14.68 mg / g for phosphate ions. Figure 2 As shown, in the low-concentration phosphorus treatment experiment of 2 mg / L, the phosphorus removal and antibacterial modified zeolite filler prepared in Example 1 achieved a phosphorus removal rate of up to 93%, while the removal rate of the original natural zeolite material prepared in Comparative Example 1 was only 6%, and the removal rate of the chitosan modified zeolite material prepared in Comparative Example 2 was 34%.

[0050] Application Example 2

[0051] Applications of antibacterial potential:

[0052] (1) Escherichia coli was cultured in 50 mL LB liquid medium for 12 h, then centrifuged at 5000 rpm for 10 min, washed several times with PBS, and stored in a 4℃ refrigerator for later use.

[0053] (2) Add a certain amount of natural zeolite from Comparative Example 1 and composite modified zeolite from Example 1 to the sterilized conical flask. Take 100 μL of the diluted bacterial solution and add it to 100 mL of phosphorus-containing solution for microbial experiments. Shake at 25 °C for 8 h.

[0054] (3) Take out the reaction system from step (2), discard the supernatant, wash the material three times with PBS buffer, and then use a vortex shaker to desorb the microorganisms attached to the surface of the material.

[0055] (4) Take 100 μL of bacterial suspension and dilute it four times in a 10-fold concentration gradient. Spread the bacterial suspension of each dilution onto LB medium and then place it in a constant temperature incubator at 37°C for 24 h. Observe the bacterial growth on the medium.

[0056] The phosphorus-removing and antibacterial modified zeolite filler prepared in Example 1 was surface-loaded with quaternized chitosan and La, which have antibacterial functions. 3+ ,like Figure 3 As shown, compared with unmodified natural zeolite, the phosphorus-removing and antibacterial modified zeolite packing prepared in Example 1 has antibacterial function and can alleviate the clogging problem of artificial wetland packing.

[0057] Example 2

[0058] A method for preparing a phosphorus-removing and antibacterial modified zeolite filler includes the following steps:

[0059] (1) Rinse the natural zeolite three times with distilled water, then soak it in distilled water for 24 hours, changing the water every 4 hours to dissolve the impurities. Dry it in a drying oven at 60°C for 12 hours. Crush the dried zeolite and put it into a container for later use.

[0060] (2) Dissolve 1 g of chitosan in 50 mL of 5% acetic acid and stir until dissolved. Slowly add 25 mL of 20% dimethyl diallyl ammonium chloride solution and mix thoroughly. Immediately place the conical flask in a 55°C constant temperature magnetic stirrer and heat for 20 min. After the reaction is complete, cool to room temperature.

[0061] (3) Add an equal volume of acetone to the reaction system of step (2) in a fume hood to generate a large amount of white flocculent matter. After centrifugation, wash three times with anhydrous ethanol. Finally, put the product into a drying oven at 60°C and dry for 24 hours. Take it out and grind it to obtain a slightly yellow powder of quaternized chitosan.

[0062] (4) Add 3g of the zeolite described in step (1) to 50mL of 0.1mol / L (La(NO)3)3·6H2O solution and stir until homogeneous. Adjust the pH to 11 and stir at room temperature for 24h. After the reaction is complete, rinse the composite modified material with deionized water and then dry it in an oven at 60℃ for 24h to obtain lanthanum modified zeolite material.

[0063] (5) Add 3g of the lanthanum-modified zeolite described in step (4) to 100mL of the quaternized chitosan solution obtained in step (3) at a concentration of 10g / L, and keep stirring on a magnetic stirrer for 4h.

[0064] (6) The solution obtained in step (5) is added dropwise to a 1 mol / L NaOH solution. Then, the lanthanum-chitosan-zeolite composite is washed with deionized water to a constant pH, then soaked in 5% glutaraldehyde overnight, and finally dried in an oven at 60°C to obtain the lanthanum and chitosan composite modified zeolite material.

[0065] Application Example 3

[0066] The phosphorus-removing and antibacterial modified zeolite packing material prepared in Example 1 was packed into a column with a cross-sectional diameter of 1 cm and a packing height of 2 cm. The water flow rate was controlled at 5 mL / min. The phosphorus-removing and antibacterial modified zeolite packing column was used to adsorb and remove phosphorus-containing wastewater with initial phosphorus concentrations of 5 mg / L, 10 mg / L, and 20 mg / L. Figure 4 As shown, under the condition of 25℃, after the phosphorus-containing wastewater was treated by the packed column, the phosphorus removal rate of the three columns reached 95% in the first 2 hours.

[0067] Comparative Example 3

[0068] A method for preparing lanthanum-modified zeolite materials includes the following steps:

[0069] (1) Rinse the natural zeolite three times with distilled water, then soak it in distilled water for 24 hours, changing the water every 4 hours to dissolve the impurities. Dry it in a drying oven at 60°C for 12 hours. Crush the dried zeolite and put it into a container for later use.

[0070] (2) Add 3g of the zeolite described in step (1) to 50mL of 0.1mol / L (La(NO)3)3·6H2O solution and stir until homogeneous. Adjust the pH to 11 and stir at room temperature for 24h. After the reaction is complete, rinse the composite modified material with deionized water and then dry it in an oven at 60℃ for 24h to obtain lanthanum modified zeolite material.

[0071] Antibacterial potential test:

[0072] Take 100 μL of a concentration of 10 7 A suspension of *E. coli* at approximately CFU / mL was poured onto the surface of a solid culture medium. The bacterial suspension was repeatedly spread using a spreading stick until it was evenly distributed on the surface of the medium. A suspension of the materials obtained in Examples 2, 1, 2, and 3 was prepared at a concentration of 0.2 g / mL. Filter paper was immersed in the suspension. Using tweezers, the filter paper containing the antibacterial material was placed in the center of the treated solid culture medium. The medium was incubated at 37°C for 24 hours, and the formation of a transparent inhibition zone was observed.

[0073] The results are as follows Figure 5As shown, a clear transparent antibacterial ring appeared around the long-lasting phosphorus removal modified zeolite material prepared in Example 2, proving that the long-lasting phosphorus removal modified zeolite material has an antibacterial effect and can alleviate the problem of biological blockage of the substrate when applied in constructed wetlands.

[0074] Example 3

[0075] A method for preparing a phosphorus-removing and antibacterial modified zeolite filler includes the following steps:

[0076] (1) Rinse the natural zeolite three times with distilled water, then soak it in distilled water for 24 hours, changing the water every 4 hours to dissolve the impurities. Dry it in a drying oven at 60°C for 12 hours. Crush the dried zeolite and put it into a container for later use.

[0077] (2) Dissolve 1 g of chitosan in 50 mL of 5% acetic acid and stir until dissolved. Slowly add 50 mL of 25 vol% dimethyl diallyl ammonium chloride solution and mix thoroughly. Immediately place the conical flask in a 50°C constant temperature magnetic stirrer and heat for 30 min. After the reaction is complete, cool to room temperature.

[0078] (3) Add an equal volume of acetone to the reaction system of step (2) in a fume hood to generate a large amount of white flocculent matter. After centrifugation, wash three times with anhydrous ethanol. Finally, put the product into a 50°C drying oven and dry for 24 hours. Take it out and grind it to obtain a slightly yellow powder of quaternized chitosan.

[0079] (4) Dissolve the quaternized chitosan in water to form a quaternized chitosan solution of 10 g / L. Add 3 g of zeolite to 100 mL of the quaternized chitosan solution and stir on a magnetic stirrer for 4 h.

[0080] (5) Add the solution obtained in step (4) dropwise into a 1 mol / L NaOH solution. Then, wash the chitosan-zeolite composite with deionized water until the pH is constant, and dry it in an oven at 50°C to obtain the chitosan-zeolite composite material.

[0081] (6) Add 3g of chitosan-zeolite composite material to 50mL of 0.5mol / L (La(NO)3)3·6H2O solution and stir until homogeneous. Adjust the pH to 14 and stir at room temperature for 24h. After the reaction is complete, rinse the composite modified material with deionized water and then dry it in an oven at 60℃ for 24h to obtain lanthanum-chitosan-zeolite composite material.

[0082] (7) The lanthanum-chitosan-zeolite composite material was mixed with cement at a mass ratio of 4:1 and granulated to form spherical particles of 4-5 mm. The particles were air-dried for 24 hours and steam-cured for 2 hours. After drying, the phosphorus-removing and antibacterial modified zeolite filler was obtained.

[0083] Example 4

[0084] A method for preparing a phosphorus-removing and antibacterial modified zeolite filler includes the following steps:

[0085] (1) Rinse the natural zeolite three times with distilled water, then soak it in distilled water for 24 hours, changing the water every 4 hours to dissolve the impurities. Dry it in a drying oven at 60°C for 12 hours. Crush the dried zeolite and put it into a container for later use.

[0086] (2) Dissolve 1 g of chitosan in 50 mL of 5% acetic acid and stir until dissolved. Slowly add 30 mL of 21 vol% dimethyl diallyl ammonium chloride solution and mix thoroughly. Immediately place the conical flask in a 60°C constant temperature magnetic stirrer and heat for 25 min. After the reaction is complete, cool to room temperature.

[0087] (3) Add an equal volume of acetone to the reaction system of step (2) in a fume hood to generate a large amount of white flocculent matter. After centrifugation, wash three times with anhydrous ethanol. Finally, put the product into a drying oven at 55°C and dry for 24 hours. Take it out and grind it to obtain a slightly yellow powder of quaternized chitosan.

[0088] (4) Dissolve the quaternized chitosan in water to form a 10 g / L quaternized chitosan solution. Add 3 g of zeolite to 80 mL of the quaternized chitosan solution and stir on a magnetic stirrer for 4 h.

[0089] (5) Add the solution obtained in step (4) dropwise into a 1 mol / L NaOH solution. Then, wash the chitosan-zeolite composite with deionized water until the pH is constant, and dry it in an oven at 55°C to obtain the chitosan-zeolite composite material.

[0090] (6) Add 3g of chitosan-zeolite composite material to 50mL of 0.3mol / L (La(NO)3)3·6H2O solution and stir until homogeneous. Adjust the pH to 12 and stir at room temperature for 24h. After the reaction is complete, rinse the composite modified material with deionized water and then dry it in an oven at 60℃ for 24h to obtain lanthanum-chitosan-zeolite composite material.

[0091] (7) The lanthanum-chitosan-zeolite composite material was mixed with cement at a mass ratio of 8:1 and granulated to form spherical particles of 4-5 mm. The particles were air-dried for 24 hours and steam-cured for 2 hours. After drying, the phosphorus-removing and antibacterial modified zeolite filler was obtained.

[0092] Example 5

[0093] A method for preparing a phosphorus-removing and antibacterial modified zeolite filler includes the following steps:

[0094] (1) Rinse the natural zeolite three times with distilled water, then soak it in distilled water for 24 hours, changing the water every 4 hours to dissolve the impurities. Dry it in a drying oven at 60°C for 12 hours. Crush the dried zeolite and put it into a container for later use.

[0095] (2) Dissolve 1 g of chitosan in 50 mL of 5% acetic acid and stir until dissolved. Slowly add 40 mL of 22 vol% dimethyl diallyl ammonium chloride solution and mix thoroughly. Immediately place the conical flask in a 52°C constant temperature magnetic stirrer and heat for 22 min. After the reaction is complete, cool to room temperature.

[0096] (3) Add an equal volume of acetone to the reaction system of step (2) in a fume hood to generate a large amount of white flocculent matter. After centrifugation, wash three times with anhydrous ethanol. Finally, put the product into a drying oven at 52°C and dry for 24 hours. Take it out and grind it to obtain a slightly yellow powder of quaternized chitosan.

[0097] (4) Dissolve the quaternized chitosan in water to form a 10 g / L quaternized chitosan solution. Add 3 g of zeolite to 70 mL of the quaternized chitosan solution and stir on a magnetic stirrer for 4 h.

[0098] (5) The solution obtained in step (4) is added dropwise to a 1 mol / L NaOH solution. Then, the chitosan-zeolite composite is washed with deionized water until the pH is constant, and dried in an oven at 52°C to obtain the chitosan-zeolite composite material.

[0099] (6) Add 3g of chitosan-zeolite composite material to 50mL of 0.2mol / L (La(NO)3)3·6H2O solution and stir until homogeneous. Adjust the pH to 13 and stir at room temperature for 24h. After the reaction is complete, rinse the composite modified material with deionized water and then dry it in an oven at 60℃ for 24h to obtain lanthanum-chitosan-zeolite composite material.

[0100] (7) The lanthanum-chitosan-zeolite composite material was mixed with cement at a mass ratio of 2:1 and granulated to form spherical particles of 4-5 mm. The particles were air-dried for 24 hours and steam-cured for 2 hours. After drying, the phosphorus-removing and antibacterial modified zeolite filler was obtained.

[0101] Example 6

[0102] A method for preparing a phosphorus-removing and antibacterial modified zeolite filler includes the following steps:

[0103] (1) Rinse the natural zeolite three times with distilled water, then soak it in distilled water for 24 hours, changing the water every 4 hours to dissolve the impurities. Dry it in a drying oven at 60°C for 12 hours. Crush the dried zeolite and put it into a container for later use.

[0104] (2) Dissolve 1 g of chitosan in 50 mL of 5% acetic acid and stir until dissolved. Slowly add 35 mL of 24 vol% dimethyl diallyl ammonium chloride solution and mix thoroughly. Immediately place the conical flask in a 58°C constant temperature magnetic stirrer and heat for 27 min. After the reaction is complete, cool to room temperature.

[0105] (3) Add an equal volume of acetone to the reaction system of step (2) in a fume hood to generate a large amount of white flocculent matter. After centrifugation, wash three times with anhydrous ethanol. Finally, put the product into a drying oven at 58°C and dry for 24 hours. Take it out and grind it to obtain a slightly yellow powder of quaternized chitosan.

[0106] (4) Dissolve the quaternized chitosan in water to form a 10 g / L quaternized chitosan solution. Add 3 g of zeolite to 60 mL of the quaternized chitosan solution and stir on a magnetic stirrer for 4 h.

[0107] (5) Add the solution obtained in step (4) dropwise into a 1 mol / L NaOH solution. Then, wash the chitosan-zeolite composite with deionized water until the pH is constant, and dry it in an oven at 58°C to obtain the chitosan-zeolite composite material.

[0108] (6) Add 3g of chitosan-zeolite composite material to 50mL of 0.4mol / L (La(NO)3)3·6H2O solution and stir until homogeneous. Adjust the pH to 11 and stir at room temperature for 24h. After the reaction is complete, rinse the composite modified material with deionized water and then dry it in an oven at 60℃ for 24h to obtain lanthanum-chitosan-zeolite composite material.

[0109] (7) The lanthanum-chitosan-zeolite composite material was mixed with cement at a mass ratio of 4:1 and granulated to form spherical particles of 4-5 mm. The particles were air-dried for 24 hours and steam-cured for 2 hours. After drying, the phosphorus-removing and antibacterial modified zeolite filler was obtained.

[0110] Example 7

[0111] 100 mg of the products obtained from Comparative Examples 1-3 and Examples 1-2 were added to 100 mL of a 2 mg / L phosphorus-containing solution. The solution was sealed with plastic wrap and placed in a constant-temperature shaker for 24 h. After the reaction, the solution was removed and allowed to stand for 5 min. The supernatant of the phosphate solution was collected using a 5 mL syringe and filtered through a 0.45 μm aqueous filter. The concentration of the remaining phosphate was determined using ammonium molybdate spectrophotometry. The results are as follows: Figure 6 The removal rate of phosphate in Comparative Example 1 was 5.64%, the removal rate of phosphate in Comparative Example 2 was 34.16%, the removal rate of phosphate in Comparative Example 3 was 90.57%, the removal rate of phosphate in Example 1 was 93.83%, and the removal rate of phosphate in Example 2 was 96.97%.

[0112] Comparative Example 4

[0113] The remaining steps of this comparative example are the same as those in Example 2, except that the (La(NO)3)3·6H2O solution in step (4) is replaced with (Nd(NO)3)3·6H2O. Phosphorus removal and antibacterial experiments were conducted, and the results showed that the phosphorus removal and antibacterial effects were lower than those in Example 2.

Claims

1. A method for preparing phosphorus removal and antibacterial modified zeolite filler for constructed wetlands, characterized in that, Includes the following steps: Step 1: Dissolve chitosan in acetic acid, stir and mix until dissolved, then add dimethyl diallyl ammonium chloride solution, mix evenly and heat to react. After the reaction is complete, cool to room temperature, then add acetone to form a precipitate, wash, dry and grind into powder to obtain quaternized chitosan. Step 2: First, mix natural zeolite with quaternized chitosan and water, stir until homogeneous, then add it dropwise to sodium hydroxide solution, wash and dry, then mix it with quaternized chitosan hexahydrate until homogeneous, adjust the pH to 11-14, stir, wash and dry; or first, mix natural zeolite with quaternized chitosan hexahydrate until homogeneous, adjust the pH to 11-14, stir, wash and dry, then mix it with quaternized chitosan and water, stir until homogeneous, then add it dropwise to sodium hydroxide solution, wash and dry, to obtain lanthanum-chitosan-zeolite composite material; Step 3: Mix the lanthanum-chitosan-zeolite composite material with cement, granulate, air dry, steam cure, and dry to obtain phosphorus-removing and antibacterial modified zeolite filler. In step one, the mass ratio of chitosan, acetic acid, and dimethyl diallyl ammonium chloride solution is 4:1:1~2. In step two, the mass ratio of natural zeolite to quaternized chitosan is 3:0.5~1, and the concentration of lanthanum nitrate hexahydrate is 0.1~0.5 mol / L; In step three, the mass ratio of the lanthanum-chitosan-zeolite composite material to cement is 2~8:

1.

2. The method for preparing a phosphorus removal and antibacterial modified zeolite filler for constructed wetlands according to claim 1, characterized in that: In step one, the volume percentage of dimethyl diallyl ammonium chloride in the dimethyl diallyl ammonium chloride solution is 20-25 vol.

3. The preparation method of the phosphorus removal and antibacterial modified zeolite filler for constructed wetlands according to claim 1, characterized in that: In step one, the heating temperature is 50~60℃ and the reaction time is 20~30min.

4. The method for preparing a phosphorus removal and antibacterial modified zeolite filler for constructed wetlands according to claim 1, characterized in that: The washing and drying temperature is 50~60℃.

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