CN112371123A - Supported silver-doped manganese dioxide catalyst and preparation method and application thereof - Google Patents

Supported silver-doped manganese dioxide catalyst and preparation method and application thereof Download PDF

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CN112371123A
CN112371123A CN202011354156.1A CN202011354156A CN112371123A CN 112371123 A CN112371123 A CN 112371123A CN 202011354156 A CN202011354156 A CN 202011354156A CN 112371123 A CN112371123 A CN 112371123A
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manganese dioxide
silver
fiber
plant tannin
mass
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CN112371123B (en
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黄婷
马贺伟
陈丽飞
陈勇
王泽胜
许洁
孙清
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Jiaxing University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
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    • B01J23/68—Silver or gold with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/688—Silver or gold with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium with manganese, technetium or rhenium
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    • B01D53/46—Removing components of defined structure
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    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
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Abstract

The invention relates to the technical field of catalytic materials, and provides a preparation method of a supported silver-doped manganese dioxide catalyst, which comprises the steps of firstly utilizing plant tannin extract to pretreat skin fibers to enable the plant tannin to be attached to the surfaces of the skin fibers; then, the reaction among oxazolidine, plant tannin and the leather fiber is utilized to enable the plant tannin to be combined on the leather fiber in a covalent bond mode; then, the potassium permanganate, the silver nitrate and the plant tannin are subjected to redox reaction to realize the in-situ generation and loading of the active manganese dioxide and the silver on the leather fiber simultaneously; by controlling the dosage ratio of the potassium permanganate to the silver nitrate, the generated silver and the manganese dioxide play a synergistic catalytic role, and the catalytic removal effect of the material on formaldehyde in the air is effectively improved. Experimental results show that the removal rate of formaldehyde by the supported silver-doped manganese dioxide catalyst prepared by the preparation method provided by the invention can reach more than 87% at normal temperature.

Description

Supported silver-doped manganese dioxide catalyst and preparation method and application thereof
Technical Field
The invention relates to the technical field of catalytic materials, in particular to a supported silver-doped manganese dioxide catalyst and a preparation method and application thereof.
Background
Indoor air formaldehyde pollution has attracted great attention. The long-term formaldehyde exposure of human body can cause respiratory disease, reduce immunity, seriously threaten health. The formaldehyde in the interior decoration material is gradually released, and the release period can reach 15 years at most. The national standard GB/T18883-2002 indoor air quality Standard stipulates that the indoor formaldehyde concentration is less than 0.1mg/m3The mandatory national standard GB 50325-3And the concentration of the indoor formaldehyde in the II type civil building engineering is less than or equal to 0.08mg/m3However, at present, the indoor formaldehyde concentration is far higher than the standard requirement under most conditions in China.
One of the effective ways to solve formaldehyde pollution is to purify and remove formaldehyde in air, so that the purification of formaldehyde in indoor air becomes one of the important technologies for ensuring public health and improving life quality. Various methods for purifying indoor formaldehyde pollution have been developed, and among them, transition metal oxides, especially activated manganese dioxide, have received attention from researchers because of its low cost and its ability to effectively catalyze the decomposition of formaldehyde. Although the catalytic effect of manganese dioxide is relatively low at ambient temperatures compared to noble metal catalysts (e.g., Pt, Pd, Rh). However, the noble metal catalyst has high cost and scarce resources, so that the large-scale use is limited. Therefore, the catalytic removal of formaldehyde based on manganese dioxide has been one of the hot spots of research, wherein the improvement of the catalytic effect of manganese dioxide has been the main direction of research.
The doping method is one of means for effectively improving the catalytic activity of the metal oxide. The existing literature shows that the doping of silver can effectively improve the effect of catalytic decomposition of formaldehyde by manganese dioxide. For example, patent CN 102198404a reports a method of doping metal into manganese dioxide molecular sieve, and a silver-loaded nano manganese dioxide catalyst is obtained. However, the scheme of doping metal to manganese dioxide molecular sieve has the following drawbacks: firstly, in order to improve the catalytic effect, the doping amount of the metal is often required to be increased, but the cost for preparing the catalytic material is higher; secondly, the catalyst prepared by the scheme of doping metal into the manganese dioxide molecular sieve is powdery, is easy to accumulate and agglomerate in the using process, is easy to reduce the purification effect, and has low catalytic activity in application; the existing material of load-type active manganese dioxide has the defect that the stability of the catalytic material is low due to the fact that manganese dioxide is easy to fall off.
Disclosure of Invention
The invention aims to provide a supported silver-doped manganese dioxide catalyst, and a preparation method and application thereof.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of a supported silver-doped manganese dioxide catalyst, which comprises the following steps:
(1) mixing the skin fiber, water and plant tannin extract, and performing adsorption reaction to obtain the skin fiber with the surface adsorbing the plant tannin;
(2) dispersing the skin fiber with the surface adsorbed with the plant tannin obtained in the step (1) in water, then mixing with oxazolidine solution, and reacting at 40-65 ℃ for 2-8 h to obtain plant tannin modified skin fiber;
(3) dispersing the plant tannin modified leather fiber obtained in the step (2) in water, mixing with a mixed solution of potassium permanganate and silver nitrate, and carrying out an oxidation-reduction reaction to obtain a supported silver-doped manganese dioxide catalyst;
and (3) taking 10-40 parts by mass of the sheath fiber, wherein the mass of the potassium permanganate in the mixed solution of the potassium permanganate and the silver nitrate in the step (3) is 0.35-1.5 parts, and the mass of the silver nitrate is 0.08-0.65 part.
Preferably, the plant extract of step (1) comprises a wattle extract, a myrica extract or a quebracho extract.
Preferably, the mass ratio of the hide fibers, the water and the plant tannin extract in the step (1) is (10-40): (200-800): (5-20).
Preferably, the mass concentration of the oxazolidine solution in the step (2) is 60-75%.
Preferably, the mass of the oxazolidine solution in the step (2) is 0.5-4.5 parts by mass based on 10-40 parts by mass of the sheath fiber.
Preferably, the mixing in the step (3) comprises mechanically stirring for 2-4 hours, and then standing for 8-12 hours.
The invention also provides a supported silver-doped manganese dioxide catalyst prepared by the preparation method in the technical scheme, which comprises leather fibers and silver and manganese dioxide loaded on the leather fibers; the loading amount of the manganese dioxide is 1-6% of the weight of the supported silver-doped manganese dioxide catalyst, and the loading amount of the silver is 0.2-4% of the weight of the supported silver-doped manganese dioxide catalyst.
The invention also provides the application of the supported silver-doped manganese dioxide catalyst in the technical scheme in purifying formaldehyde in air.
The invention provides a preparation method of a supported silver-doped manganese dioxide catalyst, which comprises the following steps: mixing the skin fiber, water and plant tannin extract, and performing adsorption reaction to obtain the skin fiber with the surface adsorbing the plant tannin; dispersing the obtained skin fiber with the surface adsorbed with the plant tannin in water, then mixing with oxazolidine solution, and reacting for 2-8 h at 40-65 ℃ to obtain plant tannin modified skin fiber; dispersing the obtained plant tannin modified leather fiber in water, then mixing with a mixed solution of potassium permanganate and silver nitrate, and carrying out an oxidation-reduction reaction to obtain a supported silver-doped manganese dioxide catalyst; the weight of the potassium permanganate in the mixed solution of the potassium permanganate and the silver nitrate is 0.35-1.5 parts, and the weight of the silver nitrate is 0.08-0.65 part, calculated by 10-40 parts of the sheath fiber. Firstly, mixing hide fiber, water and plant tannin extract, and pretreating the hide fiber by utilizing the adsorption action between the plant tannin and the hide fiber to ensure that the plant tannin is uniformly attached to the surface of the hide fiber; then, by utilizing the reaction among oxazolidine, the plant tannin and the skin fiber, the plant tannin is combined on the skin fiber in a covalent bond mode, so that the plant tannin and the skin fiber are integrated to obtain the plant tannin modified skin fiber; and then, realizing in-situ generation and loading of active manganese dioxide and silver on the leather fibers by utilizing the redox reaction of potassium permanganate, silver nitrate and plant tannin to obtain the supported silver-doped manganese dioxide catalyst. The active manganese dioxide, the silver and the leather fiber are firmly combined, and the stability is high; the invention controls the loading capacity of manganese dioxide and silver nitrate in the supported silver-doped manganese dioxide catalyst by controlling the usage amount of the sheath fiber, potassium permanganate and silver nitrate; by controlling the dosage ratio of the potassium permanganate to the silver nitrate, the generated silver and the manganese dioxide can cooperatively play a catalytic role, the dosage of the silver nitrate can be reduced, the catalyst with good catalytic performance is obtained under the condition of low silver loading, and the cost for preparing the catalyst is reduced. Experimental results show that the supported silver-doped manganese dioxide catalyst prepared by the preparation method has a good formaldehyde purification effect at normal temperature, and the formaldehyde removal rate can reach more than 87%; and the catalytic material continuously treats formaldehyde for 72 hours, has good formaldehyde removal effect and good stability.
Drawings
FIG. 1 is a graph showing the heat resistance test of a supported silver doped manganese dioxide catalyst prepared in example 1;
FIG. 2 is an X-ray diffraction pattern of a supported silver-doped manganese dioxide catalyst prepared in example 1;
FIG. 3 is a graph showing a heat resistance test of the vegetable tannin modified leather fiber prepared in comparative example 1;
FIG. 4 is an X-ray diffraction pattern of the vegetable tannin modified skin fibers prepared in comparative example 1.
FIG. 5 is a molecular structure diagram of oxazolidine form I.
Detailed Description
The invention provides a preparation method of a supported silver-doped manganese dioxide catalyst, which comprises the following steps:
(1) mixing the skin fiber, water and plant tannin extract, and performing adsorption reaction to obtain the skin fiber with the surface adsorbing the plant tannin;
(2) dispersing the skin fiber with the surface adsorbed with the plant tannin obtained in the step (1) in water, then mixing with oxazolidine solution, and reacting at 40-65 ℃ for 2-8 h to obtain plant tannin modified skin fiber;
(3) dispersing the plant tannin modified leather fiber obtained in the step (2) in water, mixing with a mixed solution of potassium permanganate and silver nitrate, and carrying out an oxidation-reduction reaction to obtain a supported silver-doped manganese dioxide catalyst;
the weight of the potassium permanganate in the mixed solution of the potassium permanganate and the silver nitrate is 0.35-1.5 parts, and the weight of the silver nitrate is 0.08-0.65 part, calculated by 10-40 parts of the sheath fiber.
The invention mixes the leather fiber, water and plant tannin extract to carry out adsorption reaction to obtain the leather fiber with the surface adsorbing the plant tannin.
In the present invention, the sheath fiber is preferably obtained from cow leather. The operation of obtaining the sheath fiber from the cowhide is not particularly limited in the present invention, and may be performed by a method known to those skilled in the art. In the present invention, the operation of the sheath fiber obtained from cow hide is preferably: sequentially cleaning, degreasing, unhairing, liming, splitting and deliming the raw material skin, and removing hair and non-skin collagen components; then removing minerals by using an acetic acid aqueous solution, adjusting the pH value to 4.8-5.0 by using an acetic acid-sodium acetate buffer solution, dehydrating by using absolute ethyl alcohol, drying under reduced pressure until the moisture content is less than 10%, and finally crushing and screening to obtain the skin fiber with the particle size of 10-20 meshes, wherein the moisture content is 9% -12%, the ash content is not more than 0.4%, and the pH value is within the range of 5.0-5.5. In the present invention, the operation of the sheath fiber obtained from cow leather is described in detail in "leather chemistry and arts (supra)" scientific Press, 2001.
In the present invention, the plant extract preferably comprises a wattle extract, a myrica extract or a quebracho extract. In the present invention, the tannin content in the plant tannin extract is preferably not less than 65%. The source of the extract of wattle, myrica or quebracho is not particularly limited in the present invention and may be any commercially available product known to those skilled in the art.
In the invention, the mass ratio of the skin fiber, the water and the plant tannin extract is preferably (10-40): (200-800): (5-20), more preferably (15-30): (300-700): (6-15). In the present invention, when the mass ratio of the hide fiber, water and plant tannin extract is in the above range, the hide fiber and plant tannin extract can be sufficiently dispersed in water, which is more favorable for the plant tannin to be uniformly adsorbed on the hide fiber.
In the present invention, the mixture of said hide fibres, water and plant tannin extract is preferably: firstly, mixing the hide fibers with water to obtain a hide fiber dispersion liquid, and then mixing the hide fiber dispersion liquid with the plant tannin extract.
In the present invention, the mixing of the sheath fiber with water is preferably performed under stirring conditions. The stirring rate is not particularly limited in the present invention, and a stirring rate known to those skilled in the art may be used. In the invention, the stirring speed is preferably 200-250 rpm. In the invention, the temperature during stirring is preferably 20-30 ℃, and more preferably 22-28 ℃; the stirring time is preferably 10-20 min, and more preferably 15 min.
In the present invention, the skin fiber dispersion liquid is subjected to an adsorption reaction during the mixing process with the plant tannin extract. In the invention, the temperature of the adsorption reaction is preferably 20-30 ℃, and more preferably 22-28 ℃; the time of the adsorption reaction is preferably 2-5 h, and more preferably 3-4 h. In the present invention, the adsorption reaction is preferably carried out under stirring. The stirring rate is not particularly limited in the present invention, and a stirring rate known to those skilled in the art may be used. In the invention, the stirring speed is preferably 200-250 rpm. In the invention, when the parameter of the adsorption reaction is in the range, the plant tannin can be adsorbed in the hide fiber more favorably. In the invention, the skin fiber and the plant tannin extract form a solid-liquid system in water, and the stirring can promote the uniform dispersion of the skin fiber and the plant tannin extract in the water, thereby being more beneficial to promoting the adsorption reaction and being more beneficial to uniformly dispersing the plant tannin on the skin fiber.
After the adsorption reaction is finished, the invention preferably carries out solid-liquid separation on the system after the adsorption reaction to obtain the skin fiber with the surface adsorbing the plant tannin. The operation of the solid-liquid separation in the present invention is not particularly limited, and the operation of the solid-liquid separation known to those skilled in the art may be employed. In the present invention, the operation of the solid-liquid separation is preferably filtration. In the present invention, said filtration enables the separation of the plant tannin extract not adsorbed to the hide fibres.
After the skin fiber with the surface adsorbed with the plant tannin is obtained, the skin fiber with the surface adsorbed with the plant tannin is dispersed in water, then mixed with oxazolidine solution, and reacted for 2-8 h at the temperature of 40-65 ℃ to obtain the plant tannin modified skin fiber.
The invention disperses the skin fiber with the surface adsorbing the plant tannin in water to obtain the skin fiber dispersion liquid with the surface adsorbing the plant tannin. In the present invention, the water is preferably 100 to 600 parts by mass, more preferably 150 to 550 parts by mass, based on 10 to 40 parts by mass of the sheath fiber. In the present invention, when the mass of the water is in the above range, the skin fibers having the plant tannin adsorbed on the surface thereof can be sufficiently dispersed.
The present invention preferably disperses the skin fibers having the plant tannin adsorbed on the surface in water under stirring. In the invention, the stirring time is preferably 10-20 min, and more preferably 15 min. The stirring speed is not particularly limited, and the solid-liquid dispersion can be realized by adopting the conventional stirring speed of a person skilled in the art. In the invention, the stirring speed is preferably 200-250 rpm. In the invention, the stirring can fully disperse the skin fiber with the surface adsorbed with the plant tannin in the water, which is beneficial to the subsequent reaction.
After the skin fiber dispersion liquid with the surface adsorbed with the plant tannin is obtained, the skin fiber dispersion liquid with the surface adsorbed with the plant tannin is mixed with oxazolidine solution, and the mixture reacts for 2-8 hours at the temperature of 40-65 ℃ to obtain the plant tannin modified skin fiber.
According to the invention, the pH value of the skin fiber dispersion liquid with the surface adsorbed with the plant tannin is preferably adjusted to 3-4, and more preferably 3-3.5 before the skin fiber dispersion liquid is mixed with the oxazolidine solution. In the present invention, the agent for adjusting the pH is preferably a weakly acidic agent, and more preferably an aqueous solution of formic acid or acetic acid. In the invention, when the pH value of the dispersion is adjusted to the range, the reaction of the oxazolidine with the skin fiber and the plant tannin is facilitated, the formation of a covalent bond is promoted, and the crosslinking effect of the oxazolidine with the skin fiber and the plant tannin is further improved.
The operation of mixing the skin fiber dispersion liquid with the surface adsorbed with the plant tannin and the oxazolidine solution is not particularly limited in the invention, and the mixing mode known to those skilled in the art can be adopted.
In the present invention, the mass concentration of the oxazolidine solution is preferably 60% to 75%, more preferably 65% to 70%. The source of the oxazolidine solution is not particularly limited in the present invention, and commercially available products well known to those skilled in the art may be used. In the invention, the structural formula of the oxazolidine is shown in figure 5.
In the present invention, the oxazolidine solution is preferably 0.5 to 4.5 parts by mass, more preferably 1.5 to 3 parts by mass, based on 10 to 40 parts by mass of the sheath fiber. In the present invention, when the mass of the oxazolidine solution is in the above range, the covalent bond reaction between the plant tannin and the skin fiber can be promoted, and the plant tannin is bonded to the skin fiber in the form of a covalent bond, thereby integrating the plant tannin and the skin fiber.
After the mixed solution of the skin fiber with the surface adsorbed with the plant tannin and the oxazolidine solution is obtained, the mixed solution of the skin fiber with the surface adsorbed with the plant tannin and the oxazolidine solution is reacted for 2-8 hours at the temperature of 40-65 ℃. In the invention, the reaction temperature is preferably 45-60 ℃, and more preferably 50-55 ℃; the reaction time is preferably 2-8 h, and more preferably 3-7 h. In the present invention, when the temperature and time of the reaction are within the above ranges, it is more advantageous to promote the formation of covalent bonds.
In the present invention, the reaction of the mixture of the surface-adsorbed vegetable tannin skin fibers and the oxazolidine solution at 40 to 65 ℃ is preferably carried out under stirring. The stirring rate is not particularly limited in the present invention, and a stirring rate known to those skilled in the art may be used. In the invention, the stirring speed is preferably 200-250 rpm. In the present invention, the stirring can promote the covalent bond reaction.
In the invention, in the reaction process of the formation of the covalent bond, oxazolidine can react with amino in the skin fiber and benzene ring in the plant tannin to form bridge bond crosslinking between the plant tannin and the skin fiber, so that the covalent bond bonding between the plant tannin and the skin fiber is promoted, and the bonding between the plant tannin and the skin fiber is stable.
After the mixed solution of the skin fiber with the surface adsorbed with the plant tannin and the oxazolidine solution is reacted for 2-8 hours at the temperature of 40-65 ℃, the invention preferably performs solid-liquid separation on the product obtained by the reaction to obtain the plant tannin modified skin fiber. The operation of the solid-liquid separation is not particularly limited in the present invention, and may be performed in a manner known to those skilled in the art. In the present invention, the solid-liquid separation is preferably filtration. In the present invention, the filtration can separate the vegetable tannin modified skin fibers obtained from the reaction from the solution.
After the plant tannin modified leather fiber is obtained, the plant tannin modified leather fiber is dispersed in water, and then is mixed with a mixed solution of potassium permanganate and silver nitrate to carry out redox reaction, so that the supported silver-doped manganese dioxide catalyst is obtained.
The vegetable tannin modified leather fiber is dispersed in water to obtain vegetable tannin modified leather fiber dispersion liquid. In the present invention, the water is preferably 100 to 600 parts by mass, more preferably 150 to 550 parts by mass, based on 10 to 40 parts by mass of the sheath fiber. In the present invention, when the water mass is in the above range, the vegetable tannin-modified skin fibers can be sufficiently dispersed in the water.
The present invention preferably disperses the vegetable tannin-modified skin fibers in water under stirring conditions. In the invention, the stirring time is preferably 10-20 min, and more preferably 15 min. The stirring speed is not particularly limited, and the solid-liquid dispersion can be realized by adopting the conventional stirring speed of a person skilled in the art. In the invention, the stirring speed is preferably 200-250 rpm. In the invention, the stirring can fully disperse the vegetable tannin modified leather fiber in water, which is beneficial to fully carrying out the subsequent oxidation-reduction reaction.
In the invention, the mass of the potassium permanganate in the mixed solution of the potassium permanganate and the silver nitrate is 0.35-1.5 parts, preferably 0.4-1.0 part, calculated by 10-40 parts of the mass of the sheath fiber; the mass of the silver nitrate is 0.04-0.65 part, preferably 0.06-0.5 part. In the invention, when the quality of the potassium permanganate and the silver nitrate in the sheath fiber and the mixed solution is in the range, the amount of doped silver can be controlled, and the weak synergetic catalysis effect of the silver and the manganese dioxide caused by the too small amount of doped silver can be prevented; and the situation that the synergistic catalysis effect is weak due to the fact that the manganese dioxide is wrapped by excessive silver doping amount can be prevented, so that the catalyst with high catalysis performance can be obtained under the condition that a small amount of silver is added, and the preparation cost of the catalyst is reduced.
In the invention, the adding speed of the mixed solution of potassium permanganate and silver nitrate is preferably 0.08-10 mL/min, and more preferably 0.1-8 mL/min. In the invention, the rate of the oxidation-reduction reaction can be controlled by controlling the dropping speed of the potassium permanganate solution, so that more active manganese dioxide and silver can be formed on the leather fiber, and the catalytic efficiency of the catalytic material can be further improved.
In the present invention, the mixing of the plant tannin modified skin fiber dispersion liquid with the mixed solution of potassium permanganate and silver nitrate preferably includes mechanical stirring and standing in sequence. In the invention, the mechanical stirring time is preferably 2-4 h, and more preferably 2.5-3.5 h. In the invention, the speed of the mechanical stirring is preferably 200-250 rpm. In the invention, the standing time is preferably 8-12 h, and more preferably 9-11 h. In the present invention, the mixing is preferably performed at room temperature, and more preferably 22 to 25 ℃. In the invention, the mixing process is an oxidation-reduction reaction process, and the stirring can promote the plant tannin modified leather fibers to contact with potassium permanganate and silver nitrate so as to promote the oxidation-reduction reaction; the standing is, on the one hand, aging to cause the formed activated manganese dioxide to be fully deposited on the sheath fibers, and, on the other hand, to cause the residual potassium permanganate in the solution to be fully reacted with the tannins on the sheath fibers.
The invention preferably adds the mixed solution of potassium permanganate and silver nitrate into the vegetable tannin modified skin fiber dispersion liquid in the process of mechanical stirring. In the invention, the adding of the mixed solution of potassium permanganate and silver nitrate into the plant tannin modified skin fiber dispersion liquid preferably comprises the following steps: adding a mixed solution of potassium permanganate and silver nitrate into the plant tannin modified skin fiber dispersion liquid in batches, dropwise adding a pH regulator after adding the mixed solution of potassium permanganate and silver nitrate each time, more preferably, dividing the mixed solution of potassium permanganate and silver nitrate into three equal parts, dropwise adding a first part of the mixed solution of potassium permanganate and silver nitrate into the plant tannin modified skin fiber dispersion liquid, and dropwise adding the pH regulator to ensure that the pH value of the system is preferably 5.2-5.8, more preferably 5.5, so as to obtain a first mixed solution system; dropwise adding a second part of the mixed solution into the first mixed solution system, and then dropwise adding a pH regulator to make the pH value of the system preferably be 4.8-5.4, more preferably 5.0, so as to obtain a second mixed solution system; and (3) after the third part of the mixed solution is dripped into the second mixed solution system, dripping a pH regulator to ensure that the pH value of the system is preferably 4.7-4.0, more preferably 4.5, and obtaining a third mixed solution system. In the invention, the plant tannin on the skin fiber reacts with potassium permanganate and silver nitrate more quickly, and the reaction sites of the plant tannin on the skin fiber are gradually reduced along with the dropwise addition, so that the reaction speed is slowed down; according to the invention, the mixed solution of potassium permanganate and silver nitrate is added in several times, and the pH value can be adjusted after the mixed solution is added every time, so that the reaction system is in an environment most favorable for the reaction of potassium permanganate and silver nitrate with plant tannin, the plant tannin on the skin fiber is promoted to react with potassium permanganate and silver nitrate, and more favorable reaction of the plant tannin with potassium permanganate and silver nitrate is carried out to generate manganese dioxide and silver.
In the present invention, the pH adjuster is preferably an organic acid, more preferably acetic acid, formic acid or citric acid. The source of the acetic acid, formic acid or citric acid is not particularly limited in the present invention, and commercially available products known to those skilled in the art may be used.
After the redox reaction is completed, the invention preferably sequentially filters, washes and dries the product of the redox reaction to obtain the supported silver-doped manganese dioxide catalyst. The operation of the filtration, washing and drying in the present invention is not particularly limited, and may be performed by a method known to those skilled in the art. In the present invention, the solvent for washing is preferably water. The invention does not specially limit the washing degree, and can remove impurities on the product supported silver doped manganese dioxide catalyst. In the invention, the washing is carried out until the aqueous solution is colorless and transparent. The temperature and time for drying are not particularly limited, and the supported silver-doped manganese dioxide catalyst can be dried. In the invention, the drying temperature is preferably 40-70 ℃, and more preferably 50 ℃; the drying time is preferably 24-48 h, and more preferably 36 h.
The preparation method of the supported silver-doped manganese dioxide catalyst provided by the invention comprises the steps of pretreating the leather fibers by using the plant tannin extract, so that the plant tannin is uniformly attached to the surfaces of the leather fibers; then, the reaction among oxazolidine, plant tannin and the leather fiber is utilized to enable the plant tannin to be combined on the leather fiber in a covalent bond mode; and then, the in-situ generation and loading of the active manganese dioxide and the silver on the skin fiber are realized by utilizing the redox reaction of potassium permanganate, silver nitrate and plant tannin, and in the obtained supported silver-doped manganese dioxide catalyst, the active manganese dioxide, the silver and the skin fiber are firmly combined, the stability is higher, and the problem that the manganese dioxide and the silver are easy to fall off is solved.
The invention also provides a supported silver-doped manganese dioxide catalyst prepared by the preparation method in the technical scheme, which comprises leather fibers and silver and manganese dioxide loaded on the leather fibers.
In the invention, the loading amount of the manganese dioxide is preferably 1-6% of the mass of the supported silver-doped manganese dioxide catalyst, and more preferably 1.5-3%; the loading amount of the silver is preferably 0.2-4% of the weight of the supported silver-doped manganese dioxide catalyst, and more preferably 0.3-2.7%. In the invention, when the loading amounts of manganese dioxide and silver in the supported silver-doped manganese dioxide catalyst are in the ranges, the loading amount of silver is less, the cost is lower, meanwhile, the synergetic catalytic effect between the silver and the manganese dioxide is strong, and the prepared catalyst has excellent catalytic effect.
In the invention, the leather fiber is firmly combined with the manganese dioxide and the silver loaded on the leather fiber, the manganese dioxide and the silver are not easy to fall off, and the stability of the catalytic material is improved.
The invention also provides the application of the supported silver-doped manganese dioxide catalyst in purifying formaldehyde in air.
In the invention, the application method of the supported silver-doped manganese dioxide catalyst in the technical scheme is not particularly limited, and a method for catalytically purifying formaldehyde in air, which is well known to those skilled in the art, can be adopted. In the present invention, the method for catalytically purifying formaldehyde in air is preferably: the catalytic material is fixed in a fixed bed through quartz wool, mixed gas of formaldehyde and air is introduced into a continuous flowing fixed bed device, and outlet gas is absorbed and derivatized through 2' 4-dinitrophenylhydrazine. The amount of the catalytic material is not particularly limited, and can be adjusted according to the amount of the mixed gas to be treated. The total flow rate of the mixed gas of formaldehyde and air is not particularly limited in the present invention, and the total flow rate of the mixed gas to be treated may be conventionally performed by those skilled in the art. The concentration of formaldehyde in the mixed gas is not particularly limited, and can be determined according to the concentration of formaldehyde in the mixed gas to be treated.
In the embodiment of the invention, when the dosage of the supported silver doped manganese dioxide catalyst is 0.5-1.5 g, the supported silver doped manganese dioxide catalyst is usedThe total flow rate of the mixed gas is preferably 400-600 mL/min; the concentration of formaldehyde in the mixed gas is preferably 50-80 mu g/m3More preferably 60 to 65 μ g/m3. In the present invention, when the amount of the supported silver-doped manganese dioxide catalyst and the concentration of formaldehyde in the mixed gas and the mixed gas are within the above ranges, formaldehyde in the mixed gas can be sufficiently removed, so that the supported silver-doped manganese dioxide catalyst can be used for purifying low-concentration formaldehyde in air.
In the invention, the scheme for detecting the application effect of the supported silver-doped manganese dioxide catalyst in purifying formaldehyde in air is preferably to determine the gas absorbed and derivatized by 2', 4-dinitrophenylhydrazine by using a liquid chromatograph. The type of the liquid chromatograph is not particularly limited in the present invention, and a liquid chromatograph known to those skilled in the art may be used. In the present invention, the liquid chromatograph is preferably an agilent 1200 or 1260 with UV or DAD detector.
In the invention, the supported silver-doped manganese dioxide catalyst, namely manganese dioxide and silver, are uniformly distributed on the leather fiber, so that the catalytic activity is higher, the manganese dioxide and silver are firmly combined with the leather fiber, the catalytic material is good in stability, and the catalytic material can be suitable for purifying formaldehyde in air.
In order to further illustrate the present invention, the following detailed description is provided in connection with examples, which should not be construed to limit the scope of the invention.
Example 1
(1) Weighing 10g of 10-20 meshes of skin fiber, adding the 10g of skin fiber into 200g of water, stirring for 10min at the temperature of 25 ℃, then adding 7.8g of wattle bark tannin extract with the tannin content of 70%, and continuously stirring for 3h at the temperature of 25 ℃ to carry out adsorption reaction; filtering to obtain skin fiber with plant tannin adsorbed on the surface; (the mass ratio of the skin fiber to the water to the plant tannin extract is 10: 200: 7.8)
(2) Adding the obtained skin fiber with the surface adsorbed with the plant tannin into 200g of water, stirring for 10min, adjusting the pH value of a system to be 3.2 by using an acetic acid solution, then dropwise adding 2g of 67% oxazolidine solution, stirring for 4h at the temperature of 55 ℃, reacting, and filtering to obtain the plant tannin modified skin fiber; (when the mass of the sheath fiber was 10 parts, the mass of the oxazolidine solution was 2 parts.)
(3) Adding the obtained plant tannin modified skin fiber into 200g of water, stirring for 10min, dividing a mixed solution of 50mL of potassium permanganate and silver nitrate into three equal parts, dropwise adding the first part of the mixed solution into the plant tannin extract modified skin fiber dispersion liquid at the speed of 0.8mL/min, and after dropwise adding, adjusting the pH value of the system to 5.5 by using acetic acid to obtain a first mixed solution system; then, dropwise adding the second part of mixed solution into the first mixed solution system at the speed of 0.8mL/min, and after dropwise adding, adjusting the pH value of the system to 5.0 by using acetic acid to obtain a second mixed solution system; finally, dropwise adding the third mixed solution into the second mixed solution system at the speed of 0.8mL/min, and after dropwise adding, adjusting the pH value of the system to 4.5 by using acetic acid to obtain a third mixed solution system; then stirring the obtained third mixed solution system for 3 hours, and standing for 12 hours; and filtering to separate out fibers, washing the fibers with water until the aqueous solution is colorless and transparent, and then drying the fibers at the temperature of 50 ℃ for 36 hours to obtain the supported silver-doped manganese dioxide catalyst. (based on 10 parts by mass of the sheath fiber, 0.79 part by mass of potassium permanganate and 0.08 part by mass of silver nitrate)
The manganese (Mn) content in the supported silver-doped manganese dioxide catalyst was measured to be 2.5% and the silver (Ag) content was measured to be 0.5% by an atomic absorption spectrophotometer.
The supported silver-doped manganese dioxide catalyst prepared in this example was subjected to a heat resistance test using a differential scanning calorimeter, and the obtained graph is shown in fig. 1. As can be seen from FIG. 1, the thermal denaturation temperature of the supported silver-doped manganese dioxide catalyst is 109-112 ℃.
The supported silver-doped manganese dioxide catalyst prepared in this example was tested using an X-ray diffractometer and the X-ray diffraction pattern obtained is shown in figure 2. As can be seen from fig. 2, diffraction peaks appear at diffraction angles 2 θ of 37 ° and 2 θ of 66 °, indicating that the main crystal phase of the prepared sample is δ -MnO2(ii) a Meanwhile, it can be seen from fig. 2 that the manganese dioxide crystal peak is weak, indicating that manganese dioxide is well dispersed and distributed. In addition, the characteristic diffraction peak of Ag does not appear in FIG. 2 because of silverThe doping amount is less and the dispersion is high; but the Ag content in the material can be measured to be about 0.5 percent by an atomic absorption spectrophotometer.
Example 2
(1) Weighing 10g of 10-20 meshes of skin fiber, adding the 10g of skin fiber into 200g of water, stirring for 10min at the temperature of 25 ℃, then adding 7.8g of wattle bark tannin extract with the tannin content of 70%, and continuously stirring for 3h at the temperature of 25 ℃ to carry out adsorption reaction; filtering to obtain skin fiber with plant tannin adsorbed on the surface; (the mass ratio of the skin fiber to the water to the plant tannin extract is 10: 200: 7.8)
(2) Adding the obtained skin fiber with the surface adsorbed with the plant tannin into 200g of water, stirring for 10min, adjusting the pH value of a system to be 3.2 by using an acetic acid solution, then dropwise adding 2g of 67% oxazolidine solution, stirring for 4h at the temperature of 55 ℃, reacting, and filtering to obtain the plant tannin modified skin fiber; (when the mass of the sheath fiber was 10 parts, the mass of the oxazolidine solution was 2 parts.)
(3) Adding the obtained plant tannin modified leather fiber into 200g of water, stirring for 10min, dividing a mixed solution of 50mL of potassium permanganate and silver nitrate into three equal parts, dropwise adding the first mixed solution into the plant tannin modified leather fiber dispersion liquid at the speed of 0.8mL/min, and after dropwise adding, adjusting the pH value of the system to 5.5 by using acetic acid to obtain a first mixed solution system; then, dropwise adding the second part of mixed solution into the first mixed solution system at the speed of 0.8mL/min, and after dropwise adding, adjusting the pH value of the system to 5.0 by using acetic acid to obtain a second mixed solution system; finally, dropwise adding the third mixed solution into the second mixed solution system at the speed of 0.8mL/min, and after dropwise adding, adjusting the pH value of the system to 4.5 by using acetic acid to obtain a third mixed solution system; then stirring the obtained third mixed solution system for 3 hours, and standing for 12 hours; and filtering to separate out fibers, washing the fibers with water until the aqueous solution is colorless and transparent, and then drying the fibers at the temperature of 50 ℃ for 36 hours to obtain the supported silver-doped manganese dioxide catalyst. (based on 10 parts by mass of the sheath fiber, 0.79 part by mass of potassium permanganate and 0.42 part by mass of silver nitrate)
The Mn content and the Ag content of the supported silver-doped manganese dioxide catalyst are respectively measured by an atomic absorption spectrophotometer to be 2.4% and 2.2%.
Example 3
(1) Weighing 10g of 10-20 meshes of skin fiber, adding the skin fiber into 200g of water, stirring for 10min at the temperature of 25 ℃, then adding 7.6g of bayberry tannin extract with the tannin content of 72%, and continuously stirring for 3h at the temperature of 25 ℃ to carry out adsorption reaction; filtering to obtain skin fiber with plant tannin adsorbed on the surface; (the mass ratio of the skin fiber to the water to the plant tannin extract is 10: 200: 7.6)
(2) Adding the obtained skin fiber with the surface adsorbed with the plant tannin into 200g of water, stirring for 10min, adjusting the pH value of a system to be 3.2 by using an acetic acid solution, then dropwise adding 2g of 67% oxazolidine solution, stirring for 4h at the temperature of 55 ℃, reacting, and filtering to obtain the plant tannin modified skin fiber; (when the mass of the sheath fiber was 10 parts, the mass of the oxazolidine solution was 2 parts.)
(3) Adding the obtained plant tannin modified leather fiber into 200g of water, stirring for 10min, dividing a mixed solution of 50mL of potassium permanganate and silver nitrate into three equal parts, dropwise adding the first mixed solution into the plant tannin modified leather fiber dispersion liquid at the speed of 0.8mL/min, and after dropwise adding, adjusting the pH value of the system to 5.5 by using acetic acid to obtain a first mixed solution system; then, dropwise adding the second part of mixed solution into the first mixed solution system at the speed of 0.8mL/min, and after dropwise adding, adjusting the pH value of the system to 5.0 by using acetic acid to obtain a second mixed solution system; finally, dropwise adding the third mixed solution into the second mixed solution system at the speed of 0.8mL/min, and after dropwise adding, adjusting the pH value of the system to 4.5 by using acetic acid to obtain a third mixed solution system; then stirring the obtained third mixed solution system for 3 hours, and standing for 12 hours; and filtering to separate out fibers, washing the fibers with water until the aqueous solution is colorless and transparent, and then drying the fibers at the temperature of 50 ℃ for 36 hours to obtain the supported silver-doped manganese dioxide catalyst. (based on 10 parts by mass of the sheath fiber, 0.79 part by mass of potassium permanganate and 0.1 part by mass of silver nitrate)
The Mn content of the supported silver-doped manganese dioxide catalyst is measured to be 2.6 percent and the Ag content is measured to be 0.6 percent by an atomic absorption spectrophotometer.
Example 4
(1) Weighing 10g of 10-20 meshes of skin fiber, adding the 10g of skin fiber into 200g of water, stirring for 10min at the temperature of 25 ℃, adding 8.4g of bayberry tannin extract with the tannin content of 72%, and continuously stirring for 3h at the temperature of 25 ℃ to perform adsorption reaction; filtering to obtain skin fiber with plant tannin adsorbed on the surface; (the mass ratio of the skin fiber to the water to the plant tannin extract is 10: 200:8.4)
(2) Adding the obtained skin fiber with the surface adsorbed with the plant tannin into 200g of water, stirring for 10min, adjusting the pH value of a system to be 3.2 by using an acetic acid solution, then dropwise adding 2g of 67% oxazolidine solution, stirring for 4h at the temperature of 55 ℃, reacting, and filtering to obtain the plant tannin modified skin fiber; (when the mass of the sheath fiber was 10 parts, the mass of the oxazolidine solution was 2 parts.)
(3) Adding the obtained plant tannin modified leather fiber into 200g of water, stirring for 10min, dividing a mixed solution of 50mL of potassium permanganate and silver nitrate into three equal parts, dropwise adding the first mixed solution into the plant tannin modified leather fiber dispersion liquid at the speed of 0.8mL/min, and after dropwise adding, adjusting the pH value of the system to 5.5 by using acetic acid to obtain a first mixed solution system; then, dropwise adding the second part of mixed solution into the first mixed solution system at the speed of 0.8mL/min, and after dropwise adding, adjusting the pH value of the system to 5.0 by using acetic acid to obtain a second mixed solution system; finally, dropwise adding the third mixed solution into the second mixed solution system at the speed of 0.8mL/min, and after dropwise adding, adjusting the pH value of the system to 4.5 by using acetic acid to obtain a third mixed solution system; then stirring the obtained third mixed solution system for 3 hours, and standing for 12 hours; and filtering to separate out fibers, washing the fibers with water until the aqueous solution is colorless and transparent, and then drying the fibers at the temperature of 50 ℃ for 36 hours to obtain the supported silver-doped manganese dioxide catalyst. (based on 10 parts by mass of the sheath fiber, 0.79 part by mass of potassium permanganate and 0.42 part by mass of silver nitrate)
The Mn content and the Ag content of the supported silver-doped manganese dioxide catalyst are respectively measured by an atomic absorption spectrophotometer to be 2.6% and 2.1%.
Comparative example 1
(1) Weighing 10g of 10-20 meshes of skin fiber, adding the 10g of skin fiber into 200g of water, stirring for 10min at the temperature of 25 ℃, then adding 7.8g of wattle bark tannin extract with the tannin content of 70%, and continuously stirring for 3h at the temperature of 25 ℃ to carry out adsorption reaction; filtering to obtain skin fiber with plant tannin adsorbed on the surface; (the mass ratio of the skin fiber to the water to the plant tannin extract is 10: 200: 7.8)
(2) Adding the obtained skin fiber with the surface adsorbed with the plant tannin into 200g of water, stirring for 10min, adjusting the pH value of a system to be 3.2 by using an acetic acid solution, then dropwise adding 2g of 67% oxazolidine solution, stirring for 4h at the temperature of 55 ℃, reacting, and filtering to obtain the plant tannin modified skin fiber; (when the mass of the sheath fiber was 10 parts, the mass of the oxazolidine solution was 2 parts.)
The plant tannin modified leather fiber prepared in the comparative example was subjected to a heat resistance test using a differential scanning calorimeter, and the obtained curve is shown in fig. 3. As can be seen from FIG. 3, the thermal denaturation temperature of the vegetable tannin modified skin fibers is about 111-113 ℃. As can be seen from a combination of fig. 1 and 3, the thermal denaturation temperatures of the two catalytic materials prepared in example 1 and comparative example 1 were substantially identical, indicating that the structure of the sheath fibers was not destroyed during the introduction of the silver-doped active manganese dioxide.
The vegetable tannin modified leather fiber prepared in the example was tested by an X-ray diffractometer, and the X-ray diffraction pattern obtained is shown in fig. 4. As can be seen from fig. 4, the vegetable tannin-modified leather fiber prepared in comparative example 1 did not show a manganese dioxide diffraction peak.
Comparative example 2
(1) Weighing 10g of 10-20 meshes of skin fiber, adding the skin fiber into 200g of water, stirring for 10min at the temperature of 25 ℃, then adding 7.6g of bayberry tannin extract with the tannin content of 72%, and continuously stirring for 3h at the temperature of 25 ℃ to carry out adsorption reaction; filtering to obtain skin fiber with plant tannin adsorbed on the surface; (the mass ratio of the skin fiber to the water to the plant tannin extract is 10: 200: 7.6)
(2) Adding the obtained skin fiber with the surface adsorbed with the plant tannin into 200g of water, stirring for 10min, adjusting the pH value of a system to be 3.2 by using an acetic acid solution, then dropwise adding 2g of 67% oxazolidine solution, stirring for 4h at the temperature of 55 ℃, reacting, and filtering to obtain the plant tannin modified skin fiber; (when the mass of the sheath fiber was 10 parts, the mass of the oxazolidine solution was 2 parts.)
Comparative example 3
(1) Weighing 10g of 10-20 meshes of skin fiber, adding the 10g of skin fiber into 200g of water, stirring for 10min at the temperature of 25 ℃, then adding 7.8g of wattle bark tannin extract with the tannin content of 70%, and continuously stirring for 3h at the temperature of 25 ℃ to carry out adsorption reaction; filtering to obtain skin fiber with plant tannin adsorbed on the surface; (the mass ratio of the skin fiber to the water to the plant tannin extract is 10: 200: 7.8)
(2) Adding the obtained skin fiber with the surface adsorbed with the plant tannin into 200g of water, stirring for 10min, adjusting the pH value of a system to be 3.2 by using an acetic acid solution, then dropwise adding 2g of 67% oxazolidine solution, stirring for 4h at the temperature of 55 ℃, reacting, and filtering to obtain the plant tannin modified skin fiber; (when the mass of the sheath fiber was 10 parts, the mass of the oxazolidine solution was 2 parts.)
(3) Adding the obtained plant tannin modified leather fiber into 200g of water, stirring for 10min, then adding 50mL of potassium permanganate solution with the concentration of 0.1mol/L at the speed of 0.8mL/min, stirring for 3h after the dropwise addition is finished, and standing for 12 h; and filtering to separate out the fibers, washing the fibers with water until the aqueous solution is colorless and transparent, and then drying the fibers at the temperature of 50 ℃ for 36 hours to obtain the catalytic material with the active manganese dioxide supported on the fibers. (Potassium permanganate 0.79 part by mass of sheath fiber 10 parts)
The mass percentage of Mn in the material is measured to be 2.5 percent by an atomic absorption spectrophotometer.
Comparative example 4
(1) Weighing 10g of 10-20 meshes of skin fiber, adding the 10g of skin fiber into 200g of water, stirring for 10min at the temperature of 25 ℃, then adding 7.8g of wattle bark tannin extract with the tannin content of 70%, and continuously stirring for 3h at the temperature of 25 ℃ to carry out adsorption reaction; filtering to obtain skin fiber with plant tannin adsorbed on the surface; (the mass ratio of the skin fiber to the water to the plant tannin extract is 10: 200: 7.8)
(2) Adding the obtained skin fiber with the surface adsorbed with the plant tannin into 200g of water, stirring for 10min, adjusting the pH value of a system to be 3.2 by using an acetic acid solution, then dropwise adding 2g of 67% oxazolidine solution, stirring for 4h at the temperature of 55 ℃, reacting, and filtering to obtain the plant tannin modified skin fiber; (when the mass of the sheath fiber was 10 parts, the mass of the oxazolidine solution was 2 parts.)
(3) Adding the obtained plant tannin modified leather fiber into 200g of water, stirring for 10min, then adding 50mL of silver nitrate solution at the speed of 0.8mL/min, stirring for 3h after the dropwise addition is finished, and standing for 12 h; filtering to separate out the fiber, washing with water for 3 times, and drying the fiber at the temperature of 50 ℃ for 36 hours to obtain the catalytic material with the silver loaded on the leather fiber. (silver nitrate in an amount of 0.1 part by mass when the sheath fiber is 10 parts by mass)
The mass percentage of Ag in the material is 0.6 percent measured by an atomic absorption spectrophotometer.
Application example 1
The application performance of the supported silver-doped manganese dioxide catalysts prepared in examples 1 to 4 was tested: introducing mixed gas of formaldehyde and air into a continuous flowing fixed bed device, wherein the pressure is normal pressure, the total flow of the gas is 500mL/min, and the concentration of the formaldehyde is 60-65 mu g/m3To (c) to (d); 0.8g of catalytic material was fixed in a fixed bed by quartz wool. And (3) absorbing and derivatizing outlet gas by using 2' 4-dinitrophenylhydrazine, and then determining by using a liquid chromatograph. The experiment was carried out continuously for 72h at 25 ℃ and the average removal of formaldehyde at different times is shown in Table 1.
TABLE 1 removal of formaldehyde from supported silver doped manganese dioxide catalysts prepared in examples 1-4
Figure BDA0002802100340000161
As can be seen from table 1, the supported silver-doped manganese dioxide catalysts prepared in examples 1 and 3 have formaldehyde removal rates of 86% or more, and the removal effects of the supported silver-doped manganese dioxide catalysts are the best; the materials prepared in examples 2 and 4 have formaldehyde removal rate of more than 82%, which shows that the materials prepared from different plant tannin extracts have certain difference in practical effect, but have better formaldehyde removal rate.
Application example 2
0.8g of the vegetable tannin extract treated skin fibers prepared in comparative examples 1 and 2 were respectively loaded into a fixed bed, and the experimental conditions were the same as those of application example 1, and the formaldehyde removal rate was continuously 72 hours at 25 ℃ as shown in Table 2.
TABLE 2 removal of formaldehyde from materials prepared in comparative examples 1-2
Figure BDA0002802100340000171
As can be seen from table 2, the skin fibers treated with the plant tannin prepared in comparative examples 1 to 2 do not contain active manganese dioxide and silver, and have a certain removal effect on formaldehyde, but the removal efficiency is obviously low, and the maximum removal rate is only about 32.8%; meanwhile, along with the prolonging of the treatment time, the formaldehyde removal rate is obviously reduced, because the process mainly has an adsorption effect; when the adsorption is saturated, the formaldehyde is not removed. The reason why the formaldehyde removal rate is high and stable in table 1 is that the active manganese dioxide and silver in the catalytic material are firmly combined with the sheath fiber, so that the catalytic material has good stability and can continuously catalyze and decompose formaldehyde.
0.8g of each of the materials prepared in comparative examples 3 and 4 was charged into the fixed bed, and the removal rate of formaldehyde by continuous 72 hours at 25 ℃ in the same experimental conditions as in application example 1 is shown in Table 3.
TABLE 3 removal of formaldehyde from materials prepared in comparative examples 3-4
Figure BDA0002802100340000172
As can be seen from table 3, the material prepared in comparative example 3, which contains activated manganese dioxide, has a formaldehyde removal rate of up to 80.4%, but less than the removal rate in table 1 (e.g., example 1, 87.5%); while the material prepared in comparative example 4 contained only silver, the formaldehyde removal rate was comparable to that in table 2 (up to 31.7%), indicating that the silver in the material had a weak ability to remove formaldehyde. The results in this table show that the silver doped manganese dioxide material prepared in the present invention provides better formaldehyde removal than the material containing either silver or manganese dioxide alone.
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.

Claims (8)

1. A preparation method of a supported silver doped manganese dioxide catalyst comprises the following steps:
(1) mixing the skin fiber, water and plant tannin extract, and performing adsorption reaction to obtain the skin fiber with the surface adsorbing the plant tannin;
(2) dispersing the skin fiber with the surface adsorbed with the plant tannin obtained in the step (1) in water, then mixing with oxazolidine solution, and reacting at 40-65 ℃ for 2-8 h to obtain plant tannin modified skin fiber;
(3) dispersing the plant tannin modified leather fiber obtained in the step (2) in water, mixing with a mixed solution of potassium permanganate and silver nitrate, and carrying out an oxidation-reduction reaction to obtain a supported silver-doped manganese dioxide catalyst;
and (3) taking 10-40 parts by mass of the sheath fiber, wherein the mass of the potassium permanganate in the mixed solution of the potassium permanganate and the silver nitrate in the step (3) is 0.35-1.5 parts, and the mass of the silver nitrate is 0.04-0.65 part.
2. A method according to claim 1, wherein said plant extract of step (1) comprises a wattle extract, a myrica extract or a quebracho extract.
3. The preparation method according to claim 1, characterized in that the mass ratio of the hide fibers, the water and the plant tannin extract in the step (1) is (10-40): (200-800): (5-20).
4. The preparation method according to claim 1, wherein the mass concentration of the oxazolidine solution in the step (2) is 60% to 75%.
5. The method according to claim 1, wherein the oxazolidine solution in the step (2) is in a mass of 0.5 to 4.5 parts by mass based on 10 to 40 parts by mass of the sheath fiber.
6. The preparation method of claim 1, wherein the mixing in the step (3) comprises mechanically stirring for 2-4 hours and then standing for 8-12 hours.
7. The supported silver-doped manganese dioxide catalyst prepared by the preparation method of any one of claims 1 to 6, which comprises sheath fibers and silver and manganese dioxide supported on the sheath fibers; the loading amount of the manganese dioxide is 1-6% of the weight of the supported silver-doped manganese dioxide catalyst, and the loading amount of the silver is 0.2-4% of the weight of the supported silver-doped manganese dioxide catalyst.
8. Use of the supported silver doped manganese dioxide catalyst of claim 7 for the purification of formaldehyde in air.
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CN113368901A (en) * 2021-06-11 2021-09-10 嘉兴学院 Silica gel loaded active manganese dioxide material and preparation method and application thereof
CN115000412A (en) * 2022-06-01 2022-09-02 山东省科学院新材料研究所 Preparation method and application of surface modified carbon cloth 3D framework
CN115000412B (en) * 2022-06-01 2023-11-24 山东省科学院新材料研究所 Preparation method and application of surface modified carbon cloth 3D framework

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