阅读说明：本技术 一种银-钴锰层状双氢氧化物复合材料及其制备方法和应用 (Silver-cobalt-manganese layered double hydroxide composite material and preparation method and application thereof ) 是由 姜传佳 林楚霞 余家国 叶家伟 于 2020-10-15 设计创作，主要内容包括：本发明公开了一种银-钴锰层状双氢氧化物复合材料及其制备方法和应用,所述银-钴锰层状双氢氧化物复合材料包括钴锰层状双氢氧化物基底和生长在所述钴锰层状双氢氧化物基底表面的银纳米颗粒。所述钴锰层状双氢氧化物基底通过共沉淀法制备,共沉淀在氮气氛围中进行。通过浸渍-硼氢化钠还原法在所述钴锰层状双氢氧化物基底上负载银纳米颗粒。本发明的制备工艺简单,本发明的复合材料可以在室温下高效去除室内空气中的甲醛,节能环保。(The invention discloses a silver-cobalt-manganese layered double hydroxide composite material and a preparation method and application thereof. The cobalt-manganese layered double hydroxide substrate is prepared by a coprecipitation method, and the coprecipitation is carried out in a nitrogen atmosphere. And loading silver nanoparticles on the cobalt-manganese layered double hydroxide substrate by an impregnation-sodium borohydride reduction method. The preparation process is simple, the composite material can efficiently remove formaldehyde in indoor air at room temperature, and the composite material is energy-saving and environment-friendly.)

1. The silver-cobalt-manganese layered double hydroxide composite material is characterized by comprising a cobalt-manganese layered double hydroxide substrate and silver nanoparticles growing on the surface of the cobalt-manganese layered double hydroxide substrate.

2. The silver-cobalt manganese layered double hydroxide composite material according to claim 1, characterized in that the mass percentage of the silver nanoparticles to the total mass of the composite material is between 0.02% and 0.4%, preferably between 0.05% and 0.2%.

3. The silver-cobalt manganese layered double hydroxide composite material as claimed in claim 1, wherein the specific surface area of the composite material is 100-120m²Per g, pore volume of 0.5-0.7cm³Per g, the average pore diameter is 20-30 nm;

the thickness of the cobalt-manganese layered double hydroxide substrate is 10-20 nanometers, and the particle size of the silver nanoparticles is 2-5 nanometers.

4. The silver-cobalt manganese layered double hydroxide composite material according to claim 1, wherein said cobalt manganese layered double hydroxide substrate is prepared by a co-precipitation method, the co-precipitation being performed in a nitrogen atmosphere.

5. The silver-cobalt-manganese layered double hydroxide composite material according to claim 1, wherein silver nanoparticles are supported on the cobalt-manganese layered double hydroxide substrate by an impregnation-sodium borohydride reduction method.

6. The silver-cobalt manganese layered double hydroxide composite material according to claim 4, wherein said cobalt manganese layered double hydroxide substrate is prepared by the following method:

step 1, preparing a cobalt-manganese layered double hydroxide precursor solution: dissolving cobalt nitrate hexahydrate, manganese nitrate tetrahydrate, sodium nitrate and ammonium fluoride in deionized water aerated by nitrogen, and stirring at room temperature in nitrogen atmosphere until solute is completely dissolved;

step 2, preparing cobalt-manganese layered double hydroxide: magnetically stirring the cobalt-manganese layered double hydroxide precursor solution prepared in the step 1 in a nitrogen aeration atmosphere, adding a hydrogen peroxide solution, stirring, adding a sodium hydroxide solution in the stirring process for coprecipitation, aging after the coprecipitation process is finished, centrifuging, cleaning and drying after the aging is finished to obtain the cobalt-manganese layered double hydroxide;

preferably, in the step 1, the molar ratio of cobalt nitrate hexahydrate, manganese nitrate tetrahydrate, sodium nitrate and ammonium fluoride is (1.5-2.5): 1: (4-6): (10-15);

preferably, the stirring time in the nitrogen atmosphere in the step 2 is 20-40 minutes, and when the hydrogen peroxide solution is added, the molar ratio of the hydrogen peroxide to the manganese nitrate tetrahydrate in the step 1 is (0.6-0.8): 1, stirring for 5-15 minutes after adding a hydrogen peroxide solution, wherein when a sodium hydroxide solution is added, the concentration of NaOH is 0.05-0.2mol/L, the dropping speed is 5-30 mu L/s, the pH is adjusted to 8-10, and the aging time is 6-14 hours;

preferably, after the aging is finished, the composite material is centrifugally separated, washed by deionized water and absolute ethyl alcohol in sequence, and then dried in an oven at the temperature of 40-50 ℃.

7. The silver-cobalt manganese layered double hydroxide composite material according to claim 5, wherein said cobalt manganese layered double hydroxide substrate is prepared by the following method: the silver nanoparticles are loaded by the following method:

step 1, adding silver nitrate into deionized water to obtain silver-containing solution with the concentration of 0.03-0.08 g/L;

step 2, placing the cobalt-manganese layered double hydroxide substrate in deionized water, dropwise adding the silver-containing solution, soaking, adding a sodium borohydride solution into the solution for reduction, and after reduction, centrifugally separating, washing and drying to obtain the silver-cobalt-manganese layered double hydroxide composite material;

preferably, in the step 2, the dipping time is 1-3 hours, the reduction time is 0.5-1 hour, the mixture is taken out, washed by deionized water and absolute ethyl alcohol in sequence, and then dried in an oven at 40-50 ℃.

8. Use of a silver-cobalt manganese layered double hydroxide composite material according to any one of claims 1 to 7 for the removal of formaldehyde.

9. The use according to claim 8, wherein the formaldehyde removal per g of the composite material is between 2 and 4mg at room temperature in 5 to 10 minutes.

10. The preparation method of the silver-cobalt manganese layered double hydroxide composite material is characterized by comprising the following steps of:

step 1, preparing a cobalt-manganese layered double hydroxide precursor solution: dissolving cobalt nitrate hexahydrate, manganese nitrate tetrahydrate, sodium nitrate and ammonium fluoride in deionized water aerated by nitrogen, and stirring at room temperature in nitrogen atmosphere until solute is completely dissolved;

step 2, preparing cobalt-manganese layered double hydroxide: magnetically stirring the cobalt-manganese layered double hydroxide precursor solution prepared in the step 1 in a nitrogen aeration atmosphere, adding a hydrogen peroxide solution, stirring, adding a sodium hydroxide solution in the stirring process for coprecipitation, aging after the coprecipitation process is finished, centrifuging, cleaning and drying after the aging is finished to obtain the cobalt-manganese layered double hydroxide;

step 3, adding silver nitrate into deionized water to obtain silver-containing solution with the concentration of 0.03-0.08 g/L;

step 4, placing the cobalt-manganese layered double hydroxide substrate obtained in the step 2 into deionized water, dropwise adding the silver-containing solution, soaking, adding a sodium borohydride solution into the solution for reduction, and performing centrifugal separation, washing and drying after reduction to obtain a silver-cobalt-manganese layered double hydroxide composite material;

preferably, in the step 1, the molar ratio of cobalt nitrate hexahydrate, manganese nitrate tetrahydrate, sodium nitrate and ammonium fluoride is (1.5-2.5): 1: (4-6): (10-15);

preferably, the stirring time in the nitrogen atmosphere in the step 2 is 20-40 minutes, and when the hydrogen peroxide solution is added, the molar ratio of the hydrogen peroxide to the manganese nitrate tetrahydrate in the step 1 is (0.6-0.8): 1, stirring for 5-15 minutes after adding a hydrogen peroxide solution, wherein when a sodium hydroxide solution is added, the concentration of NaOH is 0.05-0.2mol/L, the dropping speed is 5-30 mu L/s, the pH is adjusted to 8-10, and the aging time is 6-14 hours; after the aging is finished, centrifugally separating out the composite material, sequentially cleaning the composite material by using deionized water and absolute ethyl alcohol, and then drying the composite material in an oven at the temperature of 40-50 ℃;

preferably, in the step 4, the dipping time is 1-3 hours, the reduction time is 0.5-1 hour, the mixture is taken out, washed by deionized water and absolute ethyl alcohol in sequence, and then dried in an oven at 40-50 ℃.

Technical Field

The invention relates to the technical field of material chemistry, in particular to a silver-cobalt-manganese layered double hydroxide composite material and a preparation method and application thereof.

Background

Formaldehyde is a main indoor air pollutant and is derived from furniture and other building decoration materials, cosmetics, detergents and other daily necessities, and cooking, incense burning, smoking and other household activities. Formaldehyde has a series of health effects on the human body, including causing morbid architectural syndrome, increasing the risk of developing cancer, causing chromosome aberration, changing the number of blood cells, causing fetal malformation, etc., and has been identified as a carcinogen. Therefore, how to effectively remove formaldehyde in air has become an urgent problem to be solved, and research and development of a high-efficiency, high-performance, and high-stability removal material to remove formaldehyde in air in a large amount in a short time has been the direction of much research.

Disclosure of Invention

The invention aims to provide a silver-cobalt-manganese layered double hydroxide composite material aiming at the problems of low stability, low removal efficiency or harsh removal conditions of materials for removing formaldehyde in the prior art.

The invention also aims to provide a preparation method of the silver-cobalt manganese layered double hydroxide composite material.

The invention also aims to provide application of the silver-cobalt manganese layered double hydroxide composite material as a formaldehyde removing material.

The technical scheme adopted for realizing the purpose of the invention is as follows:

a silver-cobalt manganese layered double hydroxide composite material comprises a cobalt manganese layered double hydroxide substrate and silver nanoparticles growing on the surface of the cobalt manganese layered double hydroxide substrate.

In the technical scheme, the mass of the silver nanoparticles accounts for 0.02-0.4% of the total mass of the composite material, and preferably 0.05-0.2%;

the specific surface area of the composite material is 100-120m²Per g, pore volume of 0.5-0.7cm³(ii)/g, the average pore diameter is 20-30 nm.

In the technical scheme, the thickness of the cobalt-manganese layered double hydroxide substrate is 10-20 nm, and the particle size of the silver nanoparticles is 2-5 nm.

In the technical scheme, the cobalt-manganese layered double hydroxide substrate is prepared by a coprecipitation method, and the coprecipitation is carried out in a nitrogen atmosphere.

In the technical scheme, silver nanoparticles are loaded on the cobalt-manganese layered double hydroxide substrate by an impregnation-sodium borohydride reduction method.

In the technical scheme, the cobalt-manganese layered double hydroxide substrate is prepared by the following method:

step 1, preparing a cobalt-manganese layered double hydroxide precursor solution: dissolving cobalt nitrate hexahydrate, manganese nitrate tetrahydrate, sodium nitrate and ammonium fluoride in deionized water aerated by nitrogen, and stirring at room temperature in nitrogen atmosphere until solute is completely dissolved;

step 2, preparing cobalt-manganese layered double hydroxide: and (2) magnetically stirring the cobalt-manganese layered double hydroxide precursor solution prepared in the step (1) in a nitrogen aeration atmosphere, adding a hydrogen peroxide solution, stirring, adding a sodium hydroxide solution in the stirring process for coprecipitation, aging after the coprecipitation process is finished, centrifuging, cleaning and drying after the aging is finished to obtain the cobalt-manganese layered double hydroxide.

In the technical scheme, in the step 1, the molar ratio of cobalt nitrate hexahydrate, manganese nitrate tetrahydrate, sodium nitrate and ammonium fluoride is (1.5-2.5): 1: (4-6): (10-15).

In the technical scheme, the stirring time in the nitrogen atmosphere in the step 2 is 20-40 minutes, and when the hydrogen peroxide solution is added, the molar ratio of the hydrogen peroxide to the manganese nitrate tetrahydrate in the step 1 is (0.6-0.8): 1, stirring for 5-15 minutes after adding the hydrogen peroxide solution, wherein when the sodium hydroxide solution is added, the concentration of NaOH is 0.05-0.2mol/L, the dropping speed is 5-30 mu L/s, the pH is adjusted to 8-10, and the aging time is 6-14 hours.

In the technical scheme, after the aging is finished, the composite material is centrifugally separated, washed by deionized water and absolute ethyl alcohol in sequence, and then dried in an oven at 40-50 ℃.

In the above technical solution, the silver nanoparticles are loaded by the following method:

step 1, adding silver nitrate into deionized water to obtain silver-containing solution with the concentration of 0.03-0.08 g/L;

and 2, placing the cobalt-manganese layered double hydroxide substrate in deionized water, dropwise adding the silver-containing solution, soaking, adding a sodium borohydride solution into the solution for reduction, and performing centrifugal separation, washing and drying after reduction to obtain the silver-cobalt-manganese layered double hydroxide composite material.

In the technical scheme, in the step 2, the dipping time is 1-3 hours, the reduction time is 0.5-1 hour, the obtained product is taken out, washed by deionized water and absolute ethyl alcohol in sequence, and then dried in an oven at 40 ℃.

In another aspect of the invention, the silver-cobalt manganese layered double hydroxide composite material is applied to removing formaldehyde.

In the technical scheme, the formaldehyde removal amount per g of the composite material can reach 2-4mg within 5-10 minutes at room temperature.

In another aspect of the present invention, a method for preparing a silver-cobalt-manganese layered double hydroxide composite material comprises the following steps:

step 1, preparing a cobalt-manganese layered double hydroxide precursor solution: dissolving cobalt nitrate hexahydrate, manganese nitrate tetrahydrate, sodium nitrate and ammonium fluoride in deionized water aerated by nitrogen, and stirring at room temperature in nitrogen atmosphere until solute is completely dissolved;

step 2, preparing cobalt-manganese layered double hydroxide: magnetically stirring the cobalt-manganese layered double hydroxide precursor solution prepared in the step 1 in a nitrogen aeration atmosphere, adding a hydrogen peroxide solution, stirring, adding a sodium hydroxide solution in the stirring process for coprecipitation, aging after the coprecipitation process is finished, centrifuging, cleaning and drying after the aging is finished to obtain the cobalt-manganese layered double hydroxide;

step 3, adding silver nitrate into deionized water to obtain silver-containing solution with the concentration of 0.03-0.08 g/L;

and 4, placing the cobalt-manganese layered double hydroxide substrate obtained in the step 2 into deionized water, dropwise adding the silver-containing solution, soaking, adding a sodium borohydride solution into the solution for reduction, and performing centrifugal separation, washing and drying after reduction to obtain the silver-cobalt-manganese layered double hydroxide composite material.

In the technical scheme, in the step 1, the molar ratio of cobalt nitrate hexahydrate, manganese nitrate tetrahydrate, sodium nitrate and ammonium fluoride is (1.5-2.5): 1: (4-6): (10-15);

preferably, the stirring time in the nitrogen atmosphere in the step 2 is 20-40 minutes, and when the hydrogen peroxide solution is added, the molar ratio of the hydrogen peroxide to the manganese nitrate tetrahydrate in the step 1 is (0.6-0.8): 1, stirring for 5-15 minutes after adding a hydrogen peroxide solution, wherein when a sodium hydroxide solution is added, the concentration of NaOH is 0.05-0.2mol/L, the dropping speed is 5-30 mu L/s, the pH is adjusted to 8-10, and the aging time is 6-14 hours; after the aging is finished, centrifugally separating out the composite material, sequentially cleaning the composite material by using deionized water and absolute ethyl alcohol, and then drying the composite material in an oven at the temperature of 40-50 ℃;

in the step 4, the dipping time is 1-3 hours, the reduction time is 0.5-1 hour, the obtained product is taken out, washed by deionized water and absolute ethyl alcohol in sequence, and then dried in an oven at 40 ℃.

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

1. the method selects reducible cobalt-manganese oxide with an ultrathin layered structure as a carrier of the formaldehyde removing material, can provide a larger specific surface area, is beneficial to dispersing silver nanoparticles, selects cheaper noble metal silver as an active component, and prepares the silver-cobalt-manganese layered double hydroxide composite room-temperature formaldehyde removing material which can efficiently remove formaldehyde in indoor air at room temperature without heating or illumination and special equipment requirements.

2. The preparation process is simple, high-temperature calcination is not involved, and the preparation process is easy to regulate and control; the required raw materials are cheap and easy to obtain, the production cost is low, and the requirements of wide production in practical application can be greatly met.

3. Compared with the existing silver-based formaldehyde removal material, the composite material prepared by the invention has low silver content (lower than 0.5%), and the silver nanoparticles are uniformly dispersed, so that the high formaldehyde removal efficiency of the material is ensured, and the production cost of the material is reduced.

4. The composite material prepared by the invention is in the form of earthy yellow powder, and is easy to store and process into various shapes and sizes.

Drawings

In fig. 1, (a), (b), and (c) are a scanning electron microscope photograph, a transmission electron microscope photograph, and a high-resolution transmission electron microscope photograph of the silver-cobalt-manganese layered double hydroxide composite material of example 1, respectively.

Fig. 2 is an X-ray diffraction pattern of the silver-cobalt manganese layered double hydroxide composite material of example 1.

In fig. 3, (a), (b), and (c) are respectively energy dispersive X-ray energy spectrum (EDS) surface distribution diagrams of the elements cobalt, manganese, and silver in the silver-cobalt-manganese layered double hydroxide composite material of example 1.

Fig. 4 is an X-ray photoelectron spectroscopy (XPS) graph of the silver-cobalt manganese layered double hydroxide composite obtained in example 1.

Fig. 5 is a fourier transform infrared spectrum of the silver-cobalt manganese layered double hydroxide composite material obtained in example 1.

Fig. 6 is a nitrogen adsorption desorption isotherm of the silver-cobalt manganese layered double hydroxide composite material obtained in example 1.

Fig. 7 (a) and (b) are graphs showing the concentration change data of formaldehyde and carbon dioxide in the silver-cobalt-manganese layered double hydroxide composite material obtained in example 1 of the present invention at room temperature.

Detailed Description

The present invention will be described in further detail with reference to specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

The preparation method of the silver-cobalt manganese layered double hydroxide composite material comprises the following steps:

(1) preparing a cobalt-manganese layered double hydroxide precursor solution: dissolving a certain amount of cobalt nitrate hexahydrate (0.2183g), manganese nitrate tetrahydrate (0.0941g), sodium nitrate (0.1530g) and ammonium fluoride (0.1852g) in a certain amount (250mL) of deionized water aerated with nitrogen, and stirring at room temperature under nitrogen atmosphere until the solute is completely dissolved;

(2) preparation of cobalt-manganese layered double hydroxide: magnetically stirring the cobalt-manganese layered double hydroxide precursor solution prepared in the step (1) in a nitrogen aeration atmosphere for 30 minutes, adding 25 mu L of hydrogen peroxide solution with the concentration of 30 wt% into the solution, violently stirring for 10 minutes, then adding sodium hydroxide solution while stirring, wherein the concentration of NaOH is 0.1mol/L, the dropping rate is 10 mu L/s, the pH value is adjusted to 9, after the in-situ coprecipitation process is completed, standing and aging the material at room temperature for 6 hours, separating the composite material through high-speed centrifugation (14600rpm) after the aging is completed, sequentially washing the composite material with a large amount of deionized water and absolute ethyl alcohol, and then drying the composite material in an oven at 40 ℃;

(3) preparing a silver-cobalt-manganese layered double hydroxide composite material: adding 4.0mg of silver nitrate into 100mL of deionized water to prepare a silver-containing solution (with the concentration of 0.04g/L), dispersing the cobalt-manganese layered double hydroxide material (0.1g) prepared in the step (2) into 20mL of deionized water, dropwise adding 20mL of the prepared silver-containing solution under vigorous stirring, continuously soaking for 3 hours under vigorous stirring, quickly adding 10mL of 0.2mol/L sodium borohydride solution into the solution, reducing for 1 hour, centrifuging (14600rpm) to separate a solid product, sequentially washing for 3 times by using deionized water and absolute ethyl alcohol, and then placing in an oven at 40 ℃ for drying to prepare the silver-cobalt-manganese layered double hydroxide composite material.

Example 2

The silver-cobalt manganese layered double hydroxide composite material obtained in example 1 was subjected to physicochemical property characterization.

In fig. 1, (a), (b), and (c) are a scanning electron microscope photograph, a transmission electron microscope photograph, and a high-resolution transmission electron microscope photograph of the silver-cobalt-manganese layered double hydroxide composite material obtained in example 1, respectively. As can be seen from the figure, the prepared material is of a nano flaky structure, silver nano particles are distributed uniformly, and lattice stripes with the spacing of 0.26nm in the figure correspond to {012} crystal planes of the cobalt-manganese layered double hydroxide.

Fig. 2 is an X-ray diffraction pattern of the silver-cobalt manganese layered double hydroxide composite material obtained in example 1. The spectrogram is consistent with the diffraction peak height of a PDF standard card (JCPDS No. 89-0460) of the cobalt-manganese layered double hydroxide; fewer peaks indicate higher purity of the sample. No diffraction peaks were observed which matched the standard card of silver (JCPDS No. 87-0720), mainly due to the very low silver loading and the small and uniformly dispersed particles.

Fig. 3(a), (b), and (c) are respectively energy dispersive X-ray energy spectrum (EDS) surface distribution diagrams of the elements cobalt, manganese, and silver in the silver-cobalt-manganese layered double hydroxide composite material obtained in example 1. The distribution profiles of cobalt (Co) and manganese (Mn) elements are consistent, and the formation of a cobalt-manganese compound is confirmed; silver (Ag) content is relatively low, EDS signal is weak, but distribution is uniform.

Fig. 4 is an X-ray photoelectron spectroscopy (XPS) graph of the silver-cobalt manganese layered double hydroxide composite material obtained in example 1. Scanning the XPS spectrum (FIG. 4a) showed that there were Co, Mn, Ag, O elements in the sample (the C1s peak in the spectrum was from contaminating carbon inevitably introduced during the XPS measurement). The high resolution Ag 3d spectrum (fig. 4b) shows that the silver in the sample comprises +1 valent silver and metallic state 0 valent silver; the Co 2p spectrum (fig. 4c) shows that the cobalt in the sample is +2 valent cobalt; the Mn 2p spectrum (fig. 4d) shows that the manganese in the sample includes +2, +3, and +4 manganese.

Fig. 5 is a fourier transform infrared spectrum of the silver-cobalt manganese layered double hydroxide composite material obtained in example 1. 3408cm in the figure^-1The strong absorption peak can be attributed to the material laminate and the stretching vibration peak of the hydroxyl functional group for absorbing water; 1626cm^-1The absorption peak can be attributed to the delta (H) of water adsorbed on the surface of the material₂O) bending vibration; 1474 and 1356cm^-1The strong absorption peak of the catalyst is probably caused by NO between Co-Mn double hydroxide layers₃ ^–Is caused by vibration of; 400-700cm^-1In the range (e.g., 645 and 549 cm)^-1Where) the absorption peaks are associated with metal-oxygen (Co-O and Mn-O) or metal-hydroxyl (Co-OH and Mn-OH) vibrations in the material.

Fig. 6 is a nitrogen adsorption desorption isotherm of the silver-cobalt manganese layered double hydroxide composite material obtained in example 1. The nitrogen adsorption and desorption isotherm of the material belongs to an IV-type isotherm, which indicates that mesopores and macropores exist in the material; the hysteresis ring appearing in the relative pressure range of 0.8-1.0 belongs to H3 type, and corresponds to slit type mesopores formed among the nanosheets.

Table 1 shows the actual content of silver element, and the specific surface area, pore volume, and average pore diameter of the silver-cobalt manganese layered double hydroxide composite material obtained in example 1.

TABLE 1

Example 3

Room temperature catalyzed formaldehyde removal test.

The room temperature formaldehyde removal performance of the silver-cobalt manganese layered double hydroxide composite material prepared in example 1 was tested.

The test procedure was carried out at room temperature (25 ℃ C.) with a relative humidity of 50% in a 6L chamber formaldehyde reactor. In order to eliminate the possibility of photocatalytic oxidative decomposition caused by light ray injection and reduce the influence of formaldehyde adsorbed on the inner wall of a box body of the reactor on experimental results, the inner wall of an organic glass box of the box-type formaldehyde reactor is tightly covered with a layer of aluminum foil paper. The specific test process is as follows:

firstly, 100mg of the silver-cobalt-manganese layered double hydroxide composite material is put into a dry glass culture dish with the diameter of 10cm, and the culture dish cover connected with a pulling rope is tightly covered on the culture dish filled with the sample. Then the sealed culture dish is smoothly sent to the bottom of the box type formaldehyde reactor, and a pulling rope passes through a sealing hole at the top of the reactor and is fixed outside the box. Then, injecting about 5 microliter of formaldehyde solution (38 wt%) into the box body through a formaldehyde injection port at the top of the reactor, opening a fan with the power of 5W installed at the bottom of the reactor to accelerate the flow balance of the gas in the reactor, completely volatilizing the formaldehyde solution after 2-3h, enabling the formaldehyde in the reactor to reach the adsorption/desorption balance, and extracting the gas through the formaldehyde injection port to maintain the initial concentration of the formaldehyde in the reactor at about 100 ppm. And (3) extracting a traction rope from the outside of the reaction box to uncover the culture dish cover, so that the composite material is contacted with formaldehyde, and starting a formaldehyde removal activity test for 1 h.

The concentration of formaldehyde and carbon dioxide in the reactor was measured in real time during the test using an infrared photoacoustic spectroscopy multiple gas monitor (inova Air Tech Instruments 1412 i). The performance of the composite for room temperature catalyzed formaldehyde removal was evaluated by two criteria: the first is the reduction of formaldehyde concentration at the end of the reaction, and the second is the difference (Delta CO) between carbon dioxide concentration and initial concentration at the end of the reaction₂). Generally speaking, formaldehyde reduction and CO₂The more the amount of the produced, the better the formaldehyde removing activity of the material.

The room temperature catalytic formaldehyde decomposition performance is shown by figure 7. As can be seen from FIG. 7a, the formaldehyde concentration in the reactor rapidly decreased from 100ppm to 69ppm within 6 minutes of the start of the activity test, after which the formaldehyde concentration in the reactor was substantially stabilized in the range of 68 to 72 ppm. At 20 to 60 minutes, there was a tendency for the formaldehyde concentration to rise slowly, primarily due to desorption of formaldehyde adsorbed on the inner wall of the reactor into the air in the reactor before the test began. On the other hand, as can be seen from fig. 7b, there was no significant increase in the carbon dioxide concentration in the reactor during the test, indicating that formaldehyde was removed mainly by adsorption, but the occurrence of incomplete oxidation could not be excluded. The silver-cobalt-manganese layered double hydroxide composite material prepared by the embodiment of the invention can remove formaldehyde in air at room temperature.

The silver-cobalt-manganese layered double hydroxide composite material of the present invention was prepared by adjusting the process parameters according to the contents of the present invention, and exhibited substantially the same properties as those of example 1.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.