CN110734133B - A kind of nanometer zero-valent iron-nickel composite porous material, its preparation method and its application - Google Patents

Abstract

The invention discloses a nano zero-valent iron-nickel composite porous material, a preparation method and application thereof, belonging to the technical field of water treatment, wherein the preparation method of the nano zero-valent iron-nickel composite porous material comprises the following steps: step S1, preparing nanometer zero-valent iron-nickel powder by taking natural laterite-nickel ore as a raw material; step S2, mixing the nano zero-valent iron-nickel powder with zeolite, cement, aluminum powder, quicklime, gypsum and a surfactant, and preparing a crude filler through pouring, foaming, cutting and autoclaving maintenance; and step S3, uniformly spreading the nano zero-valent iron-nickel powder on the surface of the rough filler, performing water dispersion curing, and then performing natural curing to obtain the nano zero-valent iron-nickel composite porous material. The nano zero-valent iron-nickel composite porous material prepared by the invention has a high-openness pore structure, and has higher biological activity, adsorption performance and ion exchange performance when being used as an artificial wetland substrate.

Description

A kind of nanometer zero-valent iron-nickel composite porous material, its preparation method and its application

technical field

The invention relates to the technical field of water treatment, in particular to a nano-zero-valent iron-nickel composite porous material, a preparation method and application thereof.

Background technique

With the continuous development of industrialization and economy, water pollution has brought serious long-term harm to human and biological health, especially the pollution caused by organic pollutants and heavy metal ions in water. Compared with traditional sewage treatment technology, constructed wetland system has obvious advantages such as less investment and low operating cost. It has become a sewage treatment technology with high economic and environmental benefits. It is widely used in domestic and foreign treatment of various domestic sewage and industrial Wastewater, constructed wetland system mainly uses the interaction between the filler matrix, aquatic plants and microorganisms in the wetland to purify the sewage through a series of physical, chemical and biological methods, and the filler in the system plays an important role in the wetland sewage treatment process. , is the main site of sewage treatment, which removes pollutants through interception, filtration, adsorption and precipitation.

At present, the filler matrix of constructed wetlands is mainly composed of soil, fine sand, coarse sand, gravel, broken tiles or ash, steel slag and other materials. However, these fillers simply piled up by materials generally suffer from insufficient mechanical strength, easy clogging, etc. The disadvantages of low nitrogen and phosphorus adsorption capacity, and its limited porosity, specific surface area and other properties seriously restrict the purification efficiency of constructed wetlands.

In view of the above-mentioned defects, the creator of the present invention finally obtained the present invention after a long period of research and practice.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned technical defects, the technical solution adopted in the present invention is to provide a preparation method of nano-zero-valent iron-nickel composite porous material, comprising the following steps:

Step S1, using natural laterite nickel-iron ore as a raw material to prepare nano-zero-valent iron-nickel powder;

In step S2, the nano-zero-valent iron-nickel powder is mixed with zeolite, cement, aluminum powder, quicklime, gypsum and surfactant, and the composite porous material is prepared by pouring, foaming, cutting, and autoclave curing;

In step S3, the nano-zero-valent iron-nickel powder is evenly spread on the surface of the composite porous material, and the nano-zero-valent iron-nickel powder is cured by scattered water and then naturally cured to obtain a nano-zero-valent iron-nickel composite porous material.

Optionally, step S1 specifically includes: crushing and screening the natural laterite nickel iron ore; and calcining in a reducing atmosphere to obtain the nano-zero-valent iron-nickel powder.

Optionally, the calcination temperature of the calcination in a reducing atmosphere is 200°C to 600°C, and the calcination time is 2h to 5h.

Optionally, the reducing atmosphere for calcination under reducing atmosphere includes hydrogen.

Optionally, the crushing and screening of the natural laterite nickel iron ore includes: crushing and screening the natural laterite nickel iron ore to obtain laterite nickel iron ore powder with a particle size of ≤0.0037 mm.

Optionally, the mass ratio of the nano zero-valent iron-nickel powder to the zeolite, the cement, the aluminum powder, the quicklime, the gypsum and the surfactant is 12:2:2:2: 1:1:1.

Optionally, the foaming condition in step S2 is 3.0 h to 3.5 h of gas generation at 60°C.

Optionally, the autoclaving curing conditions in step S2 are constant pressure autoclaving for 4 h to 12 h, and the autoclaving temperature is 180°C.

The present invention also provides a nano-zero-valent iron-nickel composite porous material prepared by the preparation method of the nano-zero-valent iron-nickel composite porous material according to any one of the above.

The invention also provides an application of the nano-zero-valent iron-nickel composite porous material in a constructed wetland.

Compared with the prior art, the beneficial effects of the present invention are:

1, the present invention adopts the nanometer zero-valent iron-nickel powder prepared by natural laterite nickel ore, which has relatively high chemical activity and catalytic activity, and the nanometer zero-valent iron-nickel obtained by utilizing the aerated concrete block production method as the main raw material Compared with the existing fillers, the composite porous material has higher biological activity, adsorption performance and ion exchange performance;

2. The nano-zero-valent iron-nickel composite porous material prepared by the present invention has a highly open pore structure, which provides a structural basis for the high load of microorganisms, and at the same time provides a good environment for the growth of microorganisms, which is conducive to the degradation of pollutants by microorganisms;

3. The nano-zero-valent iron-nickel composite porous material has a large specific surface area, which can effectively adsorb, filter and retain pollutants;

4. The nano-zero-valent iron-nickel composite porous material of the present invention contains nano-zero-valent iron-nickel powder, the nano-zero-valent iron-nickel powder contains nano-zero-valent nickel, and the nano-zero-valent nickel is oxidized to Ni ²⁺ On the one hand, the chemical reaction rate can be accelerated, and on the other hand, Ni ²⁺ can promote the growth of anaerobic microorganisms, so that the nano-zero-valent iron-nickel composite porous material has the functions of oxidizing ammonia nitrogen and denitrifying nitrogen.

5. The production process of the nano-zero-valent iron-nickel composite porous material is mature, reliable and convenient, and can be produced with the help of the current aerated concrete production technology, which has a high degree of mechanization and low production cost.

Description of drawings

Fig. 1 is the XRD pattern of nanometer zero-valent iron-nickel composite porous material in the embodiment of the present invention;

2 is a Micro-CT image of the outer surface of the nano-zero-valent iron-nickel composite porous material in the embodiment of the present invention;

3 is a Micro-CT image of the inner surface of the nano-zero-valent iron-nickel composite porous material in the embodiment of the present invention;

4 is a microscopic photo of protozoa and metazoa in a nano-zero-valent iron-nickel composite porous material-constructed wetland system at a resolution of 1 μm according to an embodiment of the present invention;

5 is a microscopic photo of protozoa and metazoa in the nano-zero-valent iron-nickel composite porous material-constructed wetland system at a resolution of 20 μm according to the embodiment of the present invention;

6 is a SEM image of the outer surface pores of the nano-zero-valent iron-nickel composite porous material-constructed wetland system according to the embodiment of the present invention;

FIG. 7 is a SEM image of the nano-zero-valent iron-nickel composite porous material-constructed wetland system in the embodiment of the present invention, where microorganisms are supported on the nano-zero-valent iron-nickel composite porous material.

Detailed ways

The above and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

The embodiment of the present invention provides a preparation method of nano-zero-valent iron-nickel composite porous material, comprising the following steps:

Step S1, using natural laterite nickel iron ore as raw material, preparing nanometer zero-valent iron-nickel powder;

In step S2, the nano-zero-valent iron-nickel powder is mixed with zeolite, cement, aluminum powder, quicklime, gypsum and surfactant, and the composite porous material is prepared by pouring, foaming, cutting, and autoclave curing;

In step S3, the nano-zero-valent iron-nickel powder is evenly spread on the surface of the composite porous material, and the nano-zero-valent iron-nickel composite porous material is prepared after curing with scattered water and then natural curing.

According to the present invention, the nano-zero-valent iron-nickel powder is first prepared by using laterite nickel iron ore as a raw material, and the specific steps are as follows: after crushing and sieving the laterite nickel iron ore, a laterite nickel iron having a particle size of ≤0.0037 mm is obtained ore powder, and then calcining the laterite nickel-iron ore powder in a reducing atmosphere to obtain the nano-zero-valent iron-nickel powder. The laterite nickel iron ore is crushed to increase its surface roughness, thereby increasing its specific surface area. The larger the adsorption amount of the molecule, and the larger the specific surface area of the laterite nickel iron ore, the more catalytically active sites it has, so the catalytic ability is correspondingly enhanced.

Wherein, the reducing atmosphere includes hydrogen, the calcination temperature is 200°C to 600°C, and the calcination time is 2h to 5h. The laterite nickel iron ore mainly includes hematite, goethite and nickel oxide, and when the laterite nickel iron ore is calcined in a hydrogen atmosphere, the hematite and goethite are reduced to nano-zero valent iron, Nickel oxide is reduced to nano-zero-valent nickel, and the main chemical reaction equations are shown in formulas (1) to (3):

Fe ₂ O ₃ +3H ₂ =2Fe ⁰ +3H ₂ O (1)

2FeOOH+3H ₂ =2Fe ⁰ +4H ₂ O (2)

NiO+H ₂ =Ni ⁰ +H ₂ O (3)

Next, a composite porous material is prepared, and the nano-zero-valent iron-nickel powder is mixed with the zeolite, the cement, the aluminum powder, the quicklime, the gypsum and the surfactant in a mass ratio of 12:2:2:2:1:1 : 1 to mix the ingredients, and add water to it and stir and mix for 30min to prepare a mixed slurry.

Wherein, the zeolite is used as the framework of the composite porous material, the present invention uses natural clinoptilolite, the cement is preferably Portland cement, the cement is used as a binder, the aluminum powder is used as a foaming agent, and the aluminum The powder content is 99%, the quicklime provides alkalinity, the particle size of the quicklime is less than 0.0037mm, and the quicklime content is more than 90%, the gypsum is used as a coagulant, the gypsum content is 90%, the Surfactants include laundry detergent or saponin powder.

The mixed slurry is put into a mold, and the mold is placed in an incubator for gas generation to obtain a block, wherein the temperature in the incubator is 60° C., and the gas generation time is 3.0h to 3.5h. The mold was taken out from the incubator, and the block was taken out from the mold, and the block was cut into cubes with a size of 10 mm with a brick cutter, and the cubes were placed in an autoclave Autoclave at 180°C for 4 h to 12 h to obtain a composite porous material, the composite porous material has a rich open pore structure,

In the final step S3, after the composite porous material is cooled, the nano-zero-valent iron-nickel powder is evenly spread on the surface of the composite porous material, so that the nano-zero-valent iron-nickel powder falls to the surface of the composite porous material. In the internal pores of the open pores of the composite porous material, spray water evenly on the surface of the composite porous material, and naturally maintain the composite porous material for 5 to 30 days, to obtain the nano-zero-valent iron-nickel composite porous material Material.

The invention obtains the nano-zero-valent iron-nickel powder by reducing and calcining natural laterite nickel iron ore, and uses the natural zeolite powder as a framework, high-strength Portland cement as a binder, aluminum powder as a foaming agent, and quicklime to provide Alkalinity and gypsum are used as coagulants, and washing powder or saponin powder are used as surfactants. After mixing ingredients, foaming, high-temperature autoclave molding, and finally evenly spraying the nano-zero-valent iron-nickel powder, the nanometer zero-valent iron-nickel powder is prepared. Zero-valent iron-nickel composite porous material. The raw material used is rich in resources, low in price, and the preparation method is mature and reliable, and the existing aerated concrete production process can be used to produce equipment, with high degree of mechanization and low production cost.

The invention adopts natural laterite nickel iron ore to prepare nano zero-valent iron-nickel powder, the nano-zero-valent iron-nickel composite powder contains nano-zero-valent iron and nano-zero-valent nickel, and nano-zero-valent nickel is oxidized to Ni ²⁺ , On the one hand, the electron transfer rate of nano-zero-valent iron Fe ⁰ is accelerated, thereby increasing the chemical reaction rate. The specific reaction mechanism is shown in formulas (4) to (12), and the nano-zero-valent iron-nickel powder Fe/Ni preferentially catalyzes the oxidation contaminants, and form reaction sites on the surface of the composite porous material, promote the formation of micro-galvanic cells to generate hole charges, accelerate the corrosion of the nano-zero-valent iron-nickel powder Fe/Ni, thereby improving the nano-zero valence Catalytic oxidation ability of Fe/Ni powder Fe/Ni promotes the degradation of micro-pollutants. The introduction of nano-zero-valent Ni metal can effectively improve the catalytic performance of iron-based materials, which is mainly due to the uniform distribution of fine Ni metal particles inside the material as catalytic active sites.

Fe ⁰ +2H ⁺ →Fe ²⁺ +H ₂ (9)

Fe ⁰ +2H ₂ O→Fe ²⁺ +H ₂ +2OH ^- (10)

2Ni ⁰ +H ₂ →2Ni-H(11)

Ni-H→Ni ⁰ +H ^* (12)

On the other hand, Ni ²⁺ can promote the growth of anaerobic microorganisms, so that all kinds of microorganisms are attached to the outer surface and inside of the nano-zero-valent iron-nickel composite porous material, and the microorganisms are on the outer surface of the nano-zero-valent iron-nickel composite porous material. And the internal formation of redox zoning, with the role of ammonia nitrogen oxidation and denitrification and denitrification.

XRD test was performed on the nano-zero-valent iron-nickel composite porous material, and the results are shown in FIG. 1 . Among them: Ca represents calcium oxide; H represents hematite; Fe-Ni represents nano-zero-valent iron-nickel; according to Figure 1, it can be seen that the nano-zero-valent iron-nickel composite porous material contains nano-zero-valent iron-nickel, hematite ore, calcium oxide, indicating that the nano-zero-valent iron-nickel composite porous material has been successfully prepared.

In another embodiment of the present invention, the prepared nano-zero-valent iron-nickel composite porous material is used in constructed wetlands, and the nano-zero-valent iron-nickel composite porous material is used as a constructed wetland filler to be mixed with aquatic plants such as water hyacinth, fox A constructed wetland system is constructed with algae, daffodils, spider plants, etc., and then the wastewater rich in nitrogen and phosphorus is introduced into the constructed wetland system for purification treatment.

Plants (such as aquatic plants or marsh plants, etc.), microorganisms (bacteria, fungi, etc.) and the nano-zero-valent iron-nickel composite porous material together constitute an interdependent organic system. Among them, the microorganisms in the constructed wetland system are the main force to degrade the pollutants in the water body. The aerobic microorganisms decompose most of the organic matter in the wastewater into carbon dioxide and water through respiration, and the anaerobic bacteria decompose the organic matter into carbon dioxide and methane. Nitrifying bacteria nitrify ammonium salts, and denitrifying bacteria reduce nitrate nitrogen to nitrogen gas. Through this series of actions, the main organic pollutants in the sewage can be degraded and assimilated to become part of the microbial cells, and the rest will be returned to nature as environmentally harmless inorganic substances. In addition, there are some protozoa and metazoans in the constructed wetland ecosystem. Insects and birds in the constructed wetland system can also participate in swallowing the organic particles deposited in the wetland system, and then assimilate the organic particles as nutrients. , so as to remove the particulate matter in the sewage to some extent.

The nano-zero-valent iron-nickel composite porous material prepared by the present invention has high open porosity, so that various microorganisms can be attached to the outer surface and inside of the nano-zero-valent iron-nickel composite porous material, and The zero-valent iron-nickel composite porous material forms redox zoning on the outer surface and inside, and has the functions of oxidizing ammonia nitrogen and denitrifying nitrogen at the same time. The nano-zero-valent iron-nickel composite porous material prepared by the invention can be used as an excellent microorganism carrier material with biological activity, and provides a place for the reproduction and growth of microorganisms. At the same time, the nano-zero-valent iron-nickel composite porous material as a filler also has the function of simultaneous denitrification and phosphorus removal in the constructed wetland, and can selectively adsorb ammonia nitrogen in water.

In the constructed wetland system, the plant rhizomes bring oxygen into the nano-zero-valent iron-nickel composite porous material dispersed around it, but the environment far from the plant roots is still in an anaerobic state, which forms an environmental change zone , which can improve the ability of constructed wetlands to remove complex pollutants (refractory organic matter) and nitrogen and phosphorus. The removal of most organic pollutants and nitrogen-phosphorus compounds in sewage can rely on microorganisms in the mechanism, but some pollutants such as heavy metals, sulfur, phosphorus, etc. can be reduced by the nano-zero-valent iron-nickel composite porous material and plant absorption. its concentration. The nano-zero-valent iron-nickel composite porous material can, on the one hand, remove ammonia nitrogen in wastewater by ion exchange and adsorption; The zeolite regeneration in the nano-zero-valent iron-nickel composite porous material is realized, and then iron-oxidizing bacteria and anammox bacteria that depend on nitrate are loaded. The ammonia nitrogen adsorbed by the nano-zero-valent iron-nickel composite porous material is converted into nitrate by aerobic ammonia oxidizing bacteria, and then washed into the sewage by the constructed wetland system. In the constructed wetland system, the nitrate is converted into nitrogen by denitrifying bacteria in the sewage. Not only is it beneficial to the removal of total nitrogen, but the denitrification process consumes the chemical oxygen demand (COD) in the sewage, reducing the COD load of the sewage treatment system. Using a small amount of organic matter in the gap of nano-zero-valent iron-nickel composite porous material as a carbon source, while degrading nitrate, it can oxidize ferrous minerals to form ferric hydroxide by relying on nitrate-type iron-oxidizing bacteria. In addition, the anaerobic conditions formed by the structure of the nano-zero-valent iron-nickel composite porous material itself make the denitrification reaction complete, and further improve the removal effect of nitrate nitrogen.

The nano-zero-valent iron-nickel composite porous material described in the present invention not only has the function of adsorbing ammonia nitrogen in water, but also is an efficient microbial carrier material, which can efficiently remove nitrogen and phosphorus in wastewater, and also has the function of adsorbing various organic pollutants in water. . The oxidation of nano-zero-valent Ni to Ni ²⁺ can not only accelerate the electron transfer rate of nano ^- iron, improve the chemical reaction rate, but also promote the growth of anaerobic microorganisms. The nano-zero-valent iron-nickel composite porous material can be applied to a constructed wetland matrix, as a carrier material for microorganisms, has the function of simultaneous denitrification and phosphorus removal, and is especially suitable for the treatment of eutrophic wastewater.

Example 1

The preparation steps of the nano-zero-valent iron-nickel composite porous material are as follows:

1.1 Using natural laterite nickel iron ore as raw material, calcining the laterite nickel iron ore at a temperature of 400 ° C for 3 hours in a hydrogen atmosphere to obtain nano-zero-valent iron nickel powder;

1.2 Weigh the nano zero-valent iron-nickel powder, natural zeolite powder, high-strength Portland cement, aluminum powder, quicklime, gypsum and washing powder according to the mass ratio of 12:2:2:2:1:1:1 , the above raw materials are batched, mixed, cast and foamed, and then autoclaved at 180 ° C, wherein the foaming time is 3.5h, the autoclaving time is 8h, and finally the nano zero-valent iron-nickel powder is evenly sprinkled After curing in bulk water for 20 days, the nano-zero-valent iron-nickel composite porous material was obtained;

Micro-computed tomography (Micro-CT) was performed on the nano-zero-valent iron-nickel composite porous material, and the results are shown in Figures 2-3. It can be seen that the inner and outer surfaces of the nano-zero-valent iron-nickel composite porous material are rough and porous, and its pore structure presents three-dimensional connectivity, with high porosity and high hydrophilicity, of which the porosity is 85%~ 95%, the higher porosity provides space for microorganisms to enter the nano-zero-valent iron-nickel composite porous material for attachment and growth, which is very suitable for the growth of microorganisms.

The average mesopore pore size of the nano-zero-valent iron-nickel composite porous material is 10nm-50nm, and the specific surface area is 90m ² /g-114m ² /g as measured by the nitrogen adsorption-desorption curve. The nano-zero-valent iron-nickel composite porous material The larger specific surface area is conducive to ion exchange adsorption, so that the load of microorganisms is higher, thereby improving the pollutant removal effect.

In this example, the nano-zero-valent iron-nickel composite porous material and the commercially available constructed wetland matrix were respectively loaded into two constructed wetland systems under the same conditions for pilot-scale operation and comparative test to investigate their effects on nitrogen, phosphorus and their pollutants. remove. Among them, the influent ammonia nitrogen concentration of the constructed wetland system is 10mg/L～300mg/L, the total nitrogen concentration is 10mg/L～350mg/L, the COD concentration is 10mg/L～200mg/L, and the P concentration is 0.1mg/L～ 5mg/L.

According to the results of the pilot test, the nano-zero-valent iron-nickel composite porous material-constructed wetland system composed of the nano-zero-valent iron-nickel composite porous material can achieve a removal rate of more than 97% of ammonia nitrogen and a total nitrogen removal rate of about one year. Reach over 86%, COD removal rate over 94%, P removal rate over 97%. The commercial constructed wetland matrix-constructed wetland system composed of commercially available constructed wetland substrates has a removal rate of 60% for ammonia nitrogen, 36% for total nitrogen, and 64% for COD in about a year. The removal rate was 47%.

By analyzing the composition and characteristics of protozoa and metazoans in the nano-zero-valent iron-nickel composite porous material-constructed wetland system, it can be seen that the nano-zero-valent iron-nickel composite porous material is used in the artificial wetland, and the treatment Sewage has a better effect. Figures 4-5 are photographs of the protozoa and metazoans in the nano-zero-valent iron-nickel composite porous material-constructed wetland system. From Figures 4 and 5, it is observed that the nano-zero-valent iron-nickel composite porous material- The protozoa and metazoa in constructed wetlands include rotifers, nematodes, oligochaetes, ciliates, bellworms and straw worms. Because rotifers are sensitive to organic matter and hypoxia, when dissolved organic matter is decomposed into inorganic matter, nitrogen is converted into nitrate, and the content of DO in wastewater is normal, rotifers will appear. Therefore, the appearance of rotifers also reflects the above The effluent quality of the nano-zero-valent iron-nickel composite porous material-constructed wetland system can meet the national discharge standard. The straw worm is sensitive to hypoxia, and its existence indicates that the microbes in the nano-zero-valent iron-nickel composite porous material-constructed wetland system have good oxygen supply. Nematodes are relatively sensitive to organic matter, but not particularly sensitive to oxygen. The appearance of nematodes indicates that the organic matter in the nano-zero-valent iron-nickel composite porous material-constructed wetland system has been largely degraded, and the aerobic biofilm is mature and stable.

The SEM test was performed on the nano-zero-valent iron-nickel composite porous material-constructed wetland system. The results are shown in Figures 6-7. It can be observed that the nano-zero-valent iron-nickel composite porous material has interconnected and evenly distributed macropores Most of the structures are distributed in the range of 10 μm to 20 μm. Fig. 6 shows the outer surface pore structure of the nano-zero-valent iron-nickel composite porous material, and it can be observed that the pores are wedge-shaped. This high-porosity, three-dimensional connected macroporous structure is beneficial to exert the bioconductivity of the nano-zero-valent iron-nickel composite porous material, that is, it is conducive to the adhesion and growth of microorganisms, the entry of nutrients and oxygen required by microorganisms, and the discharge of metabolites. . FIG. 7 is a SEM photograph of microorganisms loaded on the nano-zero-valent iron-nickel composite porous material. On the 7th to 15th day of operation of the nano-zero-valent iron-nickel composite porous material-constructed wetland system, there were many microorganisms adhering to the nano-zero-valent iron-nickel composite porous material, and the microorganisms were mostly filamentous and rod-shaped. Shaped bacteria, uneven distribution of microorganisms. According to the phenomenon observed by SEM, the nano-zero-valent iron-nickel composite porous material has a rough surface, which is suitable for the reproduction and growth of microorganisms.

The nano-zero-valent iron-nickel composite porous material prepared by the present invention, as a constructed wetland substrate, has a higher pollutant removal rate than the commercially available constructed wetland substrate, which is mainly due to the nano-zero-valent iron-nickel composite porous material The surface of the material is rough and has a large porosity, which provides favorable conditions for the reproduction and growth of microorganisms, and is an excellent carrier material for microorganisms; and the nano-zero-valent Ni in the nano-zero-valent iron-nickel composite porous material can be oxidized to Ni ²⁺ , Ni ²⁺ can also promote the growth of anaerobic microorganisms. In addition, the nano-zero-valent iron-nickel composite porous material has a large specific surface area, and can also effectively adsorb, filter and intercept pollutants.

Embodiment 2

2.1 Using natural laterite nickel iron ore as a raw material, calcining the laterite nickel iron ore at a temperature of 200 ° C for 5 hours in a hydrogen atmosphere to obtain nano-zero valent iron nickel powder;

2.2 Weigh the nano-zero-valent iron-nickel powder, natural zeolite powder, high-strength Portland cement, aluminum powder, quicklime, gypsum and saponin according to the mass ratio of 12:2:2:2:1:1:1 Powder, the above raw materials are batched, mixed, cast and foamed, and then autoclaved at a high temperature of 180 ° C, wherein the foaming time is 3h, the autoclaving time is 4h, and finally the nano zero-valent iron-nickel powder is evenly sprinkled The bulk water is cured for 5 days to obtain the nano-zero-valent iron-nickel composite porous material;

2.3 The nano-zero-valent iron-nickel composite porous material and the commercially available constructed wetland matrix were respectively loaded into two constructed wetland systems under the same conditions for pilot operation and comparative test to investigate the removal of nitrogen, phosphorus and pollutants.

Among them, the influent ammonia nitrogen concentration of the constructed wetland system is 10mg/L～200mg/L, the total nitrogen concentration is 10mg/L～276mg/L, the COD concentration is 15mg/L～150mg/L, and the P concentration is 0.2mg/L～ 6mg/L.

According to the results of the pilot test, the nano-zero-valent iron-nickel composite porous material-constructed wetland system composed of the nano-zero-valent iron-nickel composite porous material can achieve a removal rate of ammonia nitrogen of more than 94% and a total nitrogen removal rate of about one year. Reach over 88%, COD removal rate over 96%, P removal rate over 97%. The commercial constructed wetland matrix-constructed wetland system composed of commercially available constructed wetland substrates has a removal rate of 50% for ammonia nitrogen, 34% for total nitrogen, 54% for COD, and 54% for P removal. The rate was 57%.

Embodiment 3

3.1 Using natural laterite nickel iron ore as raw material, calcining the laterite nickel iron ore at a temperature of 600 ° C for 2 hours in a hydrogen atmosphere to obtain nano-zero-valent iron nickel powder;

3.2 Weigh the nano-zero-valent iron-nickel powder, natural zeolite powder, high-strength Portland cement, aluminum powder, quicklime, gypsum and surface activity according to the mass ratio of 12:2:2:2:1:1:1 After batching, mixing, casting and foaming for 3.5 hours, the above-mentioned raw materials were put into the autoclave curing kettle, and autoclaved for 12 hours under 12Mpa pressure and 180°C temperature, and finally sprinkled with the nano zero-valent iron evenly The nickel powder is cured in scattered water for 30 days to obtain the nano-zero-valent iron-nickel composite porous material;

3.3 The nano-zero-valent iron-nickel composite porous material and the commercially available constructed wetland matrix were respectively filled into two constructed wetland systems under the same conditions for pilot operation and comparative test to investigate the removal of nitrogen, phosphorus and pollutants.

Among them, the influent ammonia nitrogen concentration of the constructed wetland system is 10mg/L～150mg/L, the total nitrogen concentration is 10mg/L～100mg/L, the COD concentration is 10mg/L～150mg/L, and the P concentration is 0.1mg/L～ 2mg/L.

According to the results of the pilot test, the nano-zero-valent iron-nickel composite porous material-constructed wetland system composed of the nano-zero-valent iron-nickel composite porous material can achieve a removal rate of ammonia nitrogen of more than 93% and a total nitrogen removal rate of about one year. Reach more than 85%, the COD removal rate reaches more than 98%, and the P removal rate reaches more than 99%. The commercial constructed wetland matrix-constructed wetland system composed of commercially available constructed wetland substrates has a removal rate of 67% for ammonia nitrogen, 44% for total nitrogen, 64% for COD, and 64% for P removal. The rate was 27%.

The above descriptions are only preferred embodiments of the present invention, which are merely illustrative rather than limiting for the present invention. Those skilled in the art understand that many changes, modifications and even equivalents can be made within the spirit and scope defined by the claims of the present invention, but all fall within the protection scope of the present invention.

Claims (8)

1. A preparation method of a nano zero-valent iron-nickel composite porous material is characterized by comprising the following steps:

step S1, preparing nanometer zero-valent iron-nickel powder by taking natural laterite-nickel ore as a raw material; the method specifically comprises the following steps: crushing and screening the natural laterite-nickel ore to obtain laterite-nickel ore powder with the particle size of less than or equal to 0.0037mm, and calcining the laterite-nickel ore powder in a reducing atmosphere to obtain the nano zero-valent iron-nickel powder;

step S2, mixing the nano zero-valent iron-nickel powder with zeolite, cement, aluminum powder, quicklime, gypsum and a surfactant, and preparing a composite porous material through pouring, foaming, cutting and autoclaving maintenance;

and step S3, uniformly spreading the nano zero-valent iron-nickel powder on the surface of the composite porous material, and naturally curing after water dispersion curing to obtain the nano zero-valent iron-nickel composite porous material.

2. The method for preparing the nano zero-valent iron-nickel composite porous material according to claim 1, wherein the calcination temperature in the reducing atmosphere is 200 ℃ to 600 ℃, and the calcination time is 2h to 5 h.

3. The method of preparing a nano zero-valent iron-nickel composite porous material according to claim 2, wherein the reducing atmosphere calcined under a reducing atmosphere comprises hydrogen.

4. The preparation method of the nano zero-valent iron-nickel composite porous material as claimed in any one of claims 1 to 3, wherein the mass ratio of the nano zero-valent iron-nickel powder to the zeolite, the cement, the aluminum powder, the quicklime, the gypsum and the surfactant is 12:2:2:2:1: 1.

5. The method for preparing a nano zero-valent iron-nickel composite porous material according to claim 4, wherein the foaming condition in the step S2 is that gas is generated at 60 ℃ for 3.0h to 3.5 h.

6. The method for preparing a nano zero-valent iron-nickel composite porous material according to claim 5, wherein the autoclave curing condition in the step S2 is constant pressure autoclave curing for 4 to 12 hours, and the autoclave curing temperature is 180 ℃.

7. The nano zero-valent iron-nickel composite porous material prepared by the preparation method of the nano zero-valent iron-nickel composite porous material as claimed in any one of claims 1 to 6.

8. The application of the nano zero-valent iron-nickel composite porous material of claim 7 in constructed wetlands.

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