阅读说明：本技术 一种可稳定产亚硝氮的脱氨催化剂、其制备方法及应用 (Deamination catalyst capable of stably producing nitrite nitrogen, preparation method and application thereof ) 是由 陈亦力 杨恒宇 莫恒亮 刘曼曼 李锁定 丑树人 侯琴 向春 赵文芳 于 2021-09-03 设计创作，主要内容包括：本发明提供一种可稳定产亚硝氮的脱氨催化剂、其制备方法及应用,其制备方法包括以下步骤：S1.制备锰氧化物前驱体；S2.向步骤S1中所述锰氧化物前驱体中掺杂Fe～(3+)、Ca～(2+)、Mg～(2+)、H-(3)BO-(3),得到可稳定产亚硝氮的脱氨催化剂。该方法通过对锰氧化物前驱体晶体在低温梯度加热条件下掺杂多种元素,增加晶体缺陷及活性位点的含量,提高催化剂的氨氮氧化能力,使氨氮催化氧化产物均为亚硝氮并稳定积累,为后续厌氧氨氧化过程提供稳定的亚硝氮来源,从而降低水体中总氮。(The invention provides a deamination catalyst capable of stably producing nitrite nitrogen, a preparation method and application thereof, wherein the preparation method comprises the following steps: s1, preparing a manganese oxide precursor; s2, doping Fe into the manganese oxide precursor in the step S1 3+ 、Ca 2+ 、Mg 2+ 、H 3 BO 3 To obtain the deamination catalyst capable of stably producing the nitrite nitrogen. The method has the advantages that multiple elements are doped into the manganese oxide precursor crystal under the low-temperature gradient heating condition, the content of crystal defects and active sites is increased, the ammonia nitrogen oxidation capacity of the catalyst is improved, ammonia nitrogen catalytic oxidation products are all nitrite nitrogen and are stably accumulated, and stable nitrite nitrogen is provided for the subsequent anaerobic ammonia oxidation processThe source of the nitrate nitrogen, thereby reducing the total nitrogen in the water body.)

1. A method for preparing a deamination catalyst capable of stably producing nitrite nitrogen is characterized by comprising the following steps:

s1, preparing a manganese oxide precursor;

s2, to step S1Manganese oxide precursor doped with Fe³⁺、Ca²⁺、Mg²⁺、H₃BO₃To obtain the deamination catalyst capable of stably producing the nitrite nitrogen.

2. The method for preparing a deamination catalyst capable of stably producing nitrite nitrogen according to claim 1, wherein the step S1 is specifically:

adding Mn²⁺And mixing and stirring the solution and the potassium permanganate solution to obtain a suspension, and then carrying out solid-liquid separation to obtain the manganese oxide precursor.

3. The method for preparing a deamination catalyst capable of stably producing nitrite nitrogen according to claim 2, wherein the step S1 specifically comprises the steps of:

s101, preparing Mn with the concentration of 1-3g/L²⁺A solution;

s102, preparing a potassium permanganate solution with the concentration of 1.3-4.2 g/L;

s103, adding Mn of 240-720mL/min²⁺The solution is mixed and reacted with 240-720mL/min potassium permanganate solution to obtain suspension, and then the manganese oxide precursor is obtained through solid-liquid separation.

4. The method for preparing a deamination catalyst capable of stably producing nitrite nitrogen according to claim 2, wherein the step S2 specifically comprises the steps of:

s201, dispersing the manganese oxide precursor in a solvent at a feed ratio of 40-100g/L to obtain a first dispersion liquid;

s202, adding Fe into the first dispersion liquid³⁺Solution of Fe in said first dispersion³⁺The concentration is 0.3-1g/L, then the solid-liquid separation is carried out to obtain Fe³⁺A doped manganese oxide;

s203, preparing Ca with the concentration of 30-50mg/L²⁺、20-30mg/L Mg²⁺、56-109mg/L H₃BO₃The doping solution of (1), the Fe³⁺Dispersing the doped manganese oxide in the doped solution at a feed ratio of 40-100g/L, and performing solid-liquid separation to obtain the stable nitrite production solutionA nitrogen deamination catalyst.

5. The method for preparing a deamination catalyst capable of stably producing nitrite nitrogen according to claim 4, wherein the step S2 specifically comprises the steps of:

s201, dispersing the manganese oxide precursor in a solvent at a feed ratio of 40-100g/L for 1-4h at 35-55 ℃ to obtain a first dispersion liquid;

s202, heating the first dispersion liquid to 55-95 ℃, and adding Fe into the first dispersion liquid³⁺Solution of Fe in said first dispersion³⁺The concentration is 0.3-1g/L, the temperature is kept for 2-8h, and then solid-liquid separation is carried out to obtain Fe³⁺A doped manganese oxide;

s203, preparing Ca with the concentration of 30-50mg/L²⁺、20-30mg/L Mg²⁺、56-109mg/L H₃BO₃The doping solution of (1), the Fe³⁺The doped manganese oxide is dispersed in the doped solution with the feeding ratio of 40-100g/L and is dispersed for 1-6h at the temperature of 55-95 ℃, and then solid-liquid separation is carried out, thus obtaining the deamination catalyst capable of stably producing the nitrite nitrogen.

6. The method for preparing a deamination catalyst capable of stably producing nitrous nitrogen as claimed in claim 5, further comprising performing, after step S203:

s204, dispersing the solid phase obtained by the solid-liquid separation in the step S203 in NH₄ ⁺Dispersing in the solution at 35-55 ℃ for 2-6h, and then carrying out solid-liquid separation to obtain the deamination catalyst capable of stably producing the nitrite nitrogen.

7. The method for preparing a deamination catalyst capable of stably producing nitrite nitrogen according to claim 6, wherein the deamination catalyst comprises:

fe in step S202³⁺The solution being a concentrated solution of Fe³⁺The concentration of (A) is 28-70 g/L;

NH in step S204₄ ⁺The concentration of the solution is 2-80 mg/L.

8. A catalyst prepared by the method for preparing a deamination catalyst capable of stably producing nitrite nitrogen according to any one of claims 1 to 7.

9. Use of a catalyst according to claim 8 as a deamination catalyst.

10. The method for treating the ammonia nitrogen wastewater is characterized by comprising the following steps:

using the catalyst of claim 8 to perform deamination treatment on ammonia nitrogen wastewater to obtain a nitrite-rich nitrogen product; and (3) treating the nitrite nitrogen-rich product by adopting a short-range nitrification-anaerobic ammonia oxidation process.

Technical Field

The invention belongs to the technical field of deamination catalysts, and particularly relates to a deamination catalyst capable of stably producing nitrite nitrogen, and a preparation method and application thereof.

Background

Water is an important natural resource on the earth and a life carrier substance, and the problem of water resource pollution is increasingly prominent along with the rapid development of industrial and agricultural industries in China. Among water pollutants, ammonia nitrogen pollution is the most common. The large amount of ammonia nitrogen is discharged, so that algae can be abnormally propagated in rivers, lakes and the like, the dissolved oxygen is reduced, and the eutrophication of a water body is caused; the ammonia nitrogen in the water body generates nitrate ions and nitrite ions with carcinogenic effect through the action of microorganisms, and the safety of aquatic organisms and human life is threatened.

At present, the removal of ammonia nitrogen in sewage generally comprises a physical and chemical method and a biological method. The physical and chemical methods include stripping, adsorption, chemical precipitation and ion exchange. The methods have the advantages of simple process flow, high treatment efficiency, stable treatment effect and the like. However, these methods generally have the problems of high energy consumption, easy secondary pollution, etc. Biological denitrification is the most widely applied method in municipal sewage treatment at present. The traditional biological denitrification method is mainly a nitrification and denitrification method and comprises two steps of nitrification and denitrification. In the nitrification stage, ammonia oxidizing bacteria oxidize ammonia nitrogen into nitrite nitrogen under aerobic conditions, and the nitrite nitrogen is further oxidized by nitrifying bacteria. In the denitrification stage, denitrifying bacteria convert nitrate and nitrite nitrogen to nitrogen gas under anoxic conditions. The process has the advantages of stable treatment effect, simple operation, no secondary pollution, low cost and the like. However, the process needs to add carbon source and alkalinity, needs to provide higher aeration rate, and nitrifying bacteria are sensitive to the environment, which results in higher equipment cost and operation cost.

The short-cut nitrification-anaerobic ammonia oxidation process is a process for converting ammonia nitrogen into nitrogen by using nitrite nitrogen as an electron acceptor under the anoxic condition through special ammonia oxidizing bacteria, and compared with the traditional biological denitrification method, the process has the advantages of no need of adding an organic carbon source, small required aeration amount, less generated carbon emission and sludge amount, low equipment operation cost, no secondary pollution and the like, and is an important novel water treatment process. However, in the ammonia oxidation process of the process, microorganisms grow slowly, are sensitive to the environment, and the system is started slowly, so that the oxidation product nitrite nitrogen is easy to convert into nitrate nitrogen and is difficult to accumulate. Therefore, there is a need to develop an ammonia oxidation process having higher selectivity and higher oxidation efficiency.

At present, municipal sewage denitrification mainly depends on biological method (nitrification and denitrification) removal, the carbon-nitrogen ratio of urban sewage in China is generally lower, and about 70 percent of BOD 5/total nitrogen of the urban sewage is lower than 4, so that the removal of the total nitrogen is always the most outstanding difficulty in sewage deep treatment for a long time, more than 50 percent of sewage treatment plants need to add carbon source medicaments such as methanol, sodium acetate and the like for a long time, and the average adding amount of the first-level A sewage treatment plants is about 23 mg/L. The local standards such as Beijing, Kunming and the like further improve the total nitrogen limit value to 5-10mg/L, and the water quality guarantee pressure and the economic burden of the produced water of a sewage treatment plant are heavier in the key link of denitrification.

The anaerobic ammonia oxidation technology is adopted for deep denitrification of municipal sewage, a carbon source is not required to be added, and the method has great advantage in economy. However, the use of the anaerobic ammonia oxidation technology requires that the front-end process can stably generate and accumulate the nitrite nitrogen, and the ammonia nitrogen concentration of the municipal sewage is low, namely only 40mg/L, so that the front-end process is difficult to stably generate and accumulate the nitrite nitrogen, and the anaerobic ammonia oxidation technology cannot be popularized in municipal sewage treatment.

The catalytic oxidation deammoniation technology is a novel water treatment technology developed in recent years, the main component of a catalyst is iron-manganese oxide, the main action process is that ammonia nitrogen in water is oxidized into nitrate nitrogen and nitrite nitrogen on the surface of the catalyst under the aerobic condition, and the process has high oxidation efficiency, convenient operation, no secondary pollution and wide application prospect. For example, chinese patent document CN105000722B provides an active filter material preparation system for removing ammonia nitrogen in water by catalytic oxidation, which utilizes a manganese dioxide catalytic membrane loaded on a quartz sand substrate to perform oxidation treatment of ammonia nitrogen in underground water, thereby solving the problems of unstable water production and secondary pollution of ammonia nitrogen treated by a biological method, but the product after oxidation treatment by the method is nitrate ions, and cannot provide a stable nitrite nitrogen accumulation amount when used in combination with an anaerobic ammonia oxidation process.

Disclosure of Invention

The invention solves the technical problem of providing a deamination catalyst capable of stably producing nitrite nitrogen, a preparation method and application thereof.

In order to solve the above problems, an aspect of the present invention provides a method for preparing a deamination catalyst capable of stably producing nitrite nitrogen, comprising the steps of:

s1, preparing a manganese oxide precursor;

s2, doping Fe into the manganese oxide precursor in the step S1³⁺、Ca²⁺、Mg²⁺、H₃BO₃To obtain the deamination catalyst capable of stably producing the nitrite nitrogen.

The method for preparing the deamination catalyst comprises the step of doping Fe into a manganese oxide precursor³⁺、Ca²⁺、Mg²⁺、H₃BO₃The crystal lattice defect in the manganese oxide crystal can be increased, so that the active site content of the catalyst is increased, the catalytic oxidation activity of the catalyst is improved, and the products of the catalytic oxidation treatment of ammonia nitrogen wastewater are nitrite nitrogen and stably accumulated, so that the catalyst can be used for the subsequent anaerobic ammonia oxidationThe method provides a stable nitrite nitrogen source, and the two methods are combined to reduce the total nitrogen in the water body. Specifically, the crystallinity of the catalyst crystal is reduced by the Fe element doped in the crystal, the content of oxygen cavities on the surface of the catalyst is improved, the adsorption and activation of gaseous oxygen are facilitated, active oxygen species on the surface of the catalyst are increased, the stability of the catalyst is stronger, and the service life of the catalyst is longer; ca, Mg and B elements are doped in the crystal, so that the electron transfer rate on the surface of the catalyst is improved, the catalytic activity of the deammoniation catalyst is improved, and oxidation products are nitrite nitrogen.

Preferably, step S1 is specifically:

adding Mn²⁺And mixing and stirring the solution and the potassium permanganate solution to obtain a suspension, and then carrying out solid-liquid separation to obtain the manganese oxide precursor.

The process mainly involves the following equations:

3Mn²⁺+2MnO₄ ^-+2H₂O＝5MnO₂+4H⁺

2Mn²⁺+O₂+2H₂O＝2MnO₂+4H⁺

preferably, step S1 specifically includes the following steps:

s101, preparing Mn with the concentration of 1-3g/L²⁺A solution;

s102, preparing a potassium permanganate solution with the concentration of 1.3-4.2 g/L;

s103, adding Mn of 240-720mL/min²⁺The solution is mixed and reacted with 240-720mL/min potassium permanganate solution to obtain suspension, and then the manganese oxide precursor is obtained through solid-liquid separation.

Further, the solid-liquid separation is completed by adopting a filtering and washing method.

Preferably, step S2 specifically includes the following steps:

s201, dispersing the manganese oxide precursor in a solvent at a feed ratio of 40-100g/L to obtain a first dispersion liquid;

s202, adding Fe into the first dispersion liquid³⁺Solution of Fe in said first dispersion³⁺The concentration is 0.3-1g/L, then the solid-liquid separation is carried out to obtain Fe³⁺A doped manganese oxide;

s203, preparing Ca with the concentration of 30-50mg/L²⁺、20-30mg/L Mg²⁺、56-109mg/L H₃BO₃The doping solution of (1), the Fe³⁺And dispersing the doped manganese oxide in the doped solution at a feed ratio of 40-100g/L, and then carrying out solid-liquid separation to obtain the deamination catalyst capable of stably producing nitrite nitrogen.

Through a large number of experimental trials, the doping amount of the elements is adopted, so that the lattice defect amount in the catalyst is optimal, the number of active sites is the largest, and the catalytic oxidation activity of the catalyst is the highest.

Preferably, step S2 specifically includes the following steps:

s201, dispersing the manganese oxide precursor in a solvent at a feed ratio of 40-100g/L for 1-4h at 35-55 ℃ to obtain a first dispersion liquid;

s202, heating the first dispersion liquid to 55-95 ℃, and adding Fe into the first dispersion liquid³⁺Solution of Fe in said first dispersion³⁺The concentration is 0.3-1g/L, the temperature is kept for 2-8h, and then solid-liquid separation is carried out to obtain Fe³⁺A doped manganese oxide;

s203, preparing Ca with the concentration of 30-50mg/L²⁺、20-30mg/L Mg²⁺、56-109mg/L H₃BO₃The doping solution of (1), the Fe³⁺The doped manganese oxide is dispersed in the doped solution with the feeding ratio of 40-100g/L and is dispersed for 1-6h at the temperature of 55-95 ℃, and then solid-liquid separation is carried out, thus obtaining the deamination catalyst capable of stably producing the nitrite nitrogen.

The invention adopts the doping of elements in the gradient heating process, the precursor crystal is aged in the gradient heating process, and the proper temperature for doping each element is selected, so that the doping elements are more uniformly dispersed in the crystal, and the catalytic oxidation activity of the catalyst is higher.

Further, in step S2, the manganese oxide precursor is dispersed in a sodium bicarbonate solution or a sodium carbonate solution. Dispersing in sodium bicarbonate solution or sodium carbonate solution to perform alkaline washing on manganese oxide, removing excessive acid in the material, and maintaining the materialFe with weakly alkaline surface and convenient doping³⁺And (4) hydrolyzing.

Preferably, after step S203, the method further comprises:

s204, dispersing the solid phase obtained by the solid-liquid separation in the step S203 in NH₄ ⁺Dispersing in the solution at 35-55 ℃ for 2-6h, and then carrying out solid-liquid separation to obtain the deamination catalyst capable of stably producing the nitrite nitrogen.

Dispersing the solid phase after solid-liquid separation in NH₄ ⁺In solution, the deammoniation catalyst may be pre-activated to promote faster deammoniation activity of the deammoniation catalyst, specifically, NH₄ ⁺The solution may be (NH)₄)₂SO₄And (3) solution.

Preferably, the concentration of the sodium bicarbonate solution in the step S201 is 1-6 mmol/L;

fe in step S202³⁺The solution is Fe³⁺Concentrated solution of (3), Fe³⁺The concentration of (A) is 28-70 g/L;

NH in step S204₄ ⁺The concentration of the solution is 2-80 mg/L.

Preferably, the Mn is²⁺Mn in solution²⁺Is MnSO₄、MnCl₂、Mn(NO₃)₂One or a mixture of more of the above;

said Fe³⁺Fe in solution³⁺Is FeCl₃、Fe(NO₃)₃、Fe₂(SO₄)₃One or a combination of several of them;

said Ca-containing²⁺、Mg²⁺、H₃BO₃In the doping solution of (2), Ca²⁺Is CaCl₂、Ca(NO₃)₂、CaSO₄One or a mixture of more of the above; mg (magnesium)²⁺Is MgCl₂、Mg(NO₃)₂、Mg(SO₄)₂One or a mixture of several of them.

Another aspect of the present invention provides a catalyst prepared by the above method for preparing a deamination catalyst capable of stably producing nitrite nitrogen.

In a further aspect the present invention provides the use of a catalyst as described above as a deamination catalyst.

In another aspect, the invention provides a method for treating ammonia nitrogen wastewater, comprising the following steps:

carrying out deamination treatment on the ammonia nitrogen wastewater by using the catalyst to obtain a nitrite nitrogen-rich product; and (3) treating the nitrite nitrogen-rich product by adopting a short-range nitrification-anaerobic ammonia oxidation process.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention relates to a deamination catalyst capable of stably producing nitrite nitrogen, a preparation method and application thereof, wherein Fe is doped into a manganese oxide precursor³⁺、Ca²⁺、Mg²⁺、H₃BO₃The method can increase lattice defects in the manganese oxide crystal, thereby increasing the content of active sites of the catalyst, improving the catalytic oxidation activity of the catalyst, and stably accumulating nitrite nitrogen in catalytic oxidation treatment products of ammonia nitrogen wastewater, thereby providing a stable nitrite nitrogen source for a subsequent anaerobic ammonia oxidation process. Specifically, the crystallinity of the catalyst crystal is reduced by the Fe element doped in the crystal, the content of oxygen cavities on the surface of the catalyst is improved, the adsorption and activation of gaseous oxygen are facilitated, active oxygen species on the surface of the catalyst are increased, the stability of the catalyst is stronger, and the service life of the catalyst is longer; ca, Mg and B elements are doped in the crystal, so that the electron transfer rate on the surface of the catalyst is improved, the catalytic activity of the deammoniation catalyst is improved, and oxidation products are nitrite nitrogen;

2. the invention further regulates the doping amount of each element, dopes the elements in the gradient heating process and selects the proper temperature for doping each element, so that each doping element of the catalyst can be dispersed more uniformly, the lattice defect amount in the catalyst is optimal, the number of active sites is the largest, and the catalytic oxidation activity of the catalyst is the highest;

3. the deamination catalyst capable of stably producing nitrite nitrogen can be used for treating ammonia nitrogen wastewater to generate nitrite nitrogen and stably accumulate the nitrite nitrogen, is combined with a shortcut nitrification-anaerobic ammonia oxidation process, provides a stable nitrite nitrogen source for the shortcut nitrification-anaerobic ammonia oxidation process, can degrade 0-100mg/L of ammonia nitrogen only by aeration under the condition of not adding any chemical agent, and has the advantages of convenient operation, low energy consumption and cost saving.

Drawings

FIG. 1 shows a manganese oxide precursor C-MnO obtained in example 1 of the present invention_xA micro-topography of;

FIG. 2 shows the deamination catalyst MC-Fe/MnO obtained in example 1 of the present invention_xA micro-topography of;

FIG. 3 shows a manganese oxide precursor C-MnO obtained in example 2 of the present invention_xA micro-topography of;

FIG. 4 shows the deamination catalyst MC-Fe/MnO obtained in example 2 of the present invention_xA micro-topography of;

FIG. 5 shows the deamination catalyst MC-Fe/MnO obtained in example 2 of the present invention_xThe change situation of ammonia nitrogen in inlet water, nitrate nitrogen and nitrite nitrogen in produced water along with the increase of the operation time is shown in the graph.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The preparation method of the deamination catalyst capable of stably producing the nitrite nitrogen, which is described in the embodiment, comprises the following steps of:

s101, preparing MnCl with concentration of 1.5g/L₂20L of solution;

s102, preparing 20L of potassium permanganate solution with the concentration of 3.3 g/L;

s103, under the stirring condition, adding MnCl₂Adding the solution and the potassium permanganate solution into a reaction tank at equal flow rates, wherein the flow rates of the solution and the potassium permanganate solution are both 500mL/min, uniformly stirring to obtain a suspension, filtering and washing to obtain the manganese oxide precursor C-MnO_xA filter cake having a water content of about 80%;

s201, subjecting the manganese oxide precursor C-MnO_xDispersing the filter cake in a sodium bicarbonate solution with the concentration of 4mmol/L at the feed ratio of 70g/L, and heating and stirring in a water bath at the temperature of 40 ℃ for 2 hours to obtain a first dispersion liquid;

s202, heating the first dispersion liquid to 80 ℃, and dropwise adding Fe into the first dispersion liquid while stirring³⁺FeCl with concentration of 56g/L₃Solution of Fe in said first dispersion³⁺The concentration is 0.5g/L, after the dripping is finished, the mixture is stirred for 6 hours under the condition of heat preservation, and then the mixture is filtered to obtain a filter cake, namely Fe³⁺A doped manganese oxide;

s203, preparing Ca with the concentration of 28mg/L²⁺、28mg/L Mg²⁺、60mg/L H₃BO₃In (C) is₂、MgSO₄、H₃BO₃Doping solution of said Fe³⁺Dispersing the doped manganese oxide in the doped solution at a feed ratio of 70g/L, heating and stirring in a water bath at 60 ℃ for 4h, filtering and washing to obtain doped Ca²⁺、Mg²⁺、H₃BO₃Manganese oxide of (1);

s204, doping Ca obtained in the step S203²⁺、Mg²⁺、H₃BO₃Is dispersed in NH₄ ⁺NH concentration of 30mg/L₄Adding the solution into Cl solution, stirring for 2 hours in water bath at 40 ℃, and then filtering and washing to obtain the deamination catalyst filter cake MC-Fe/MnO capable of stably producing nitrite nitrogen_xAnd the water content of the filter cake is about 80 percent, thus being the deamination catalyst capable of stably producing the nitrite nitrogen. The manganese oxide precursor C-MnO obtained in this example_xAnd deamination catalyst MC-Fe/MnO_xThe microscopic morphology of (A) is shown in FIGS. 1 and 2.

Weighing precursor C-MnO_xAnd MC-Fe/MnO_x10g of each catalyst filter cake is respectively put into a laboratory self-prepared water body with the ammonia nitrogen concentration of 40 mg/L. The self-prepared water contained only ammonium chloride and sodium bicarbonate and had a pH of 7.8. After stirring with aeration for 50 hours, the deammoniation performance was measured, and the results are shown in Table 1.

Example 2

The preparation method of the deamination catalyst capable of stably producing the nitrite nitrogen, which is described in the embodiment, comprises the following steps of:

s101, preparing MnCl with concentration of 3g/L₂28L of solution;

s102, preparing 28L of potassium permanganate solution with the concentration of 4 g/L;

s103, under the stirring condition, adding MnCl₂Adding the solution and the potassium permanganate solution into a reaction tank at equal flow rates, wherein the flow rates of the solution and the potassium permanganate solution are both 300mL/min, uniformly stirring to obtain a suspension, filtering and washing to obtain the manganese oxide precursor C-MnO_xA filter cake having a water content of about 70%;

s201, subjecting the manganese oxide precursor C-MnO_xDispersing the filter cake in sodium bicarbonate solution with the concentration of 6mmol/L at the feeding ratio of 50g/L, and heating and stirring in a water bath at the temperature of 55 ℃ for 2h to obtain first dispersion liquid;

s202, heating the first dispersion liquid to 60 ℃, and dropwise adding Fe into the first dispersion liquid while stirring³⁺FeCl with concentration of 28g/L₃Solution of Fe in said first dispersion³⁺The concentration is 0.7g/L, after the dropwise addition is finished, the mixture is stirred for 8 hours under the condition of heat preservation, and then the mixture is filtered to obtain a filter cake, namely Fe³⁺A doped manganese oxide;

s203, preparing Ca with the concentration of 40mg/L²⁺、30mg/L Mg²⁺、90mg/L H₃BO₃In (C) is₂、MgSO₄、H₃BO₃Doping solution of said Fe³⁺Dispersing the doped manganese oxide in the doped solution at a feed ratio of 50g/L, heating and stirring in a water bath at 75 ℃ for 3h, filtering and washing to obtain doped Ca²⁺、Mg²⁺、H₃BO₃Manganese oxide of (1);

s204, doping Ca obtained in the step S203²⁺、Mg²⁺、H₃BO₃Is dispersed in NH₄ ⁺NH concentration of 10mg/L₄Adding the solution into Cl solution, stirring the solution for 2 hours in a water bath at the temperature of 35 ℃, and then filtering and washing the solution to obtain the deamination catalyst filter cake MC-Fe/MnO capable of stably producing nitrite nitrogen_xThe water content of the filter cake is about 75 percent, namely the stable productA catalyst for deammoniation of nitrite nitrogen. The manganese oxide precursor C-MnO obtained in this example_xAnd deamination catalyst MC-Fe/MnO_xThe micro-topography of (A) is shown in FIGS. 3 and 4.

Weighing precursor C-MnO_xAnd MC-Fe/MnO_x10g of each catalyst filter cake is added into certain municipal sewage of Beijing with the ammonia nitrogen concentration of about 40mg/L, the pH value is 8.18, and the deammoniation performance is measured after aeration stirring for 50 hours, and the result is shown in Table 1.

TABLE 1

Example 3

The deammoniation catalyst filter cake synthesized in example 2 was used to perform ammonia nitrogen catalytic oxidation test on municipal sewage of a water plant in Beijing. The ammonia nitrogen content in the inlet water is 40mg/L, and the pH value is 8.18. In the test process, the feed ratio is 10g/L (calculated according to filter cakes), the hydraulic retention time is 4 hours, the stirring and aeration are continued, the ammonia nitrogen concentration of the inlet water and the nitrate nitrogen and nitrite nitrogen concentration of the produced water are tested, and the result is shown in figure 5. The catalyst is continuously operated for 30 days, the products are all nitrite nitrogen, and the performance is not attenuated. The catalyst synthesized by the gradient heating doping method can be used for continuously and stably degrading ammonia nitrogen in municipal sewage, and the products are nitrite nitrogen.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.