CN111974156A

CN111974156A - Preparation method of scavenger for efficiently degrading gaseous pollutants

Info

Publication number: CN111974156A
Application number: CN201910441717.2A
Authority: CN
Inventors: 任晓伟; 高新华
Original assignee: Ningxia High Energy Environmental Protection Technology Co ltd; Ningxia University
Current assignee: Ningxia High Energy Environmental Protection Technology Co ltd; Ningxia University
Priority date: 2019-05-24
Filing date: 2019-05-24
Publication date: 2020-11-24

Abstract

The invention belongs to the technical field of air purification, and particularly relates to a preparation method of a noble metal-visible light degradation indoor air pollutant scavenger. The scavenger is Ag, amorphous silicon or TiO₂The nano material formed by taking the molecular sieve immersed by the surfactant as the shell has high degradation and removal effects on indoor pollutants such as formaldehyde, benzene and TVOC. The method is simple to operate, has a good purification effect, and has a certain economic value.

Description

Preparation method of scavenger for efficiently degrading gaseous pollutants

Technical Field

The invention belongs to the technical field of air purification, and particularly relates to a scavenging agent for removing formaldehyde, benzene and TVOC at room temperature and a preparation method thereof.

Background

The decoration materials are usually artificial boards, sandwich boards, glue, paint, coating, adhesives, granite, marble, ceramic tiles, gypsum and the like, and the materials contain various pollutants such as formaldehyde, benzene, ammonia, radon and the like, which form indoor air pollutants. Indoor air pollutants such as formaldehyde have irritation effect on skin mucosa, sensitization effect on human body, and can cause allergic dermatitis, mottle, bronchial asthma, etc. It also has strong carcinogenicity and carcinogenicity, and can cause nasopharyngeal carcinoma and leukemia, for example.

The problem of indoor air pollution has attracted people's attention. However, most indoor scavengers sold in the market at present are only surface sealing agents, but are not really 'decomposers of indoor pollutants such as formaldehyde'. But a film is formed on the surface of the plate or furniture to temporarily block the release of air pollutants such as formaldehyde, and once the film is damaged due to moisture or heat, the air pollutants such as formaldehyde can be emitted again, thus being harmful to the health of people.

With the increasing emphasis on the removal of air pollutants, researchers began to utilize photocatalytic TiO compounds₂However, its use for degrading indoor air pollutants also exposes some problems. Such as TiO₂The removal of indoor pollutants requires irradiation of ultraviolet light, visible light is not utilized by more than 5%, and the ultraviolet light is harmful to human bodies, so that the application of the material in the field of air purification is limited to a certain extent. Because of competitive adsorption of water and contaminants during the adsorption process, water will reduce TiO₂Activity and lifetime of the catalyst; in a photocatalytic process TiO₂The catalyst is easy to agglomerate, and the catalytic performance of the catalyst is greatly reduced.

Disclosure of Invention

The present invention is directed to overcoming the problems of the prior art as described above and providing a novel material for the catalytic degradation of indoor air pollutants. The main component of the scavenger of the invention is TiO ₂And a molecular sieve. Scavenger utilization engineered materialsUnder the irradiation of visible light, indoor pollutants such as formaldehyde, benzene and TVOC are spontaneously adsorbed, and the physical and chemical properties of the material degrade the adsorbed pollutants. The scavenger prepared by the invention belongs to a nano material and has a core-shell structure. Wherein, TiO₂Taking the molecular sieve immersed by the surfactant as a shell, and modifying by Ag element. The scavenger has dual functions of degrading catalysis and hydrophobicity. In practical application, the removal rate of indoor pollutants reaches more than 95%.

The technical scheme of the invention is as follows:

(1) mixing ammonia water and ethanol at room temperature, stirring, adjusting pH to alkalinity, preferably pH 8-9, adding titanium dioxide powder, stirring for 30min, and marking as solution A;

(2) mixing tetraethoxysilane and dimethyldiethoxysilane according to the volume ratio of 5-10: 1, mixing, and adding diatomite, wherein the diatomite accounts for 0.2-3 times of the titanium dioxide powder and is marked as solution B; quickly adding the solution B into the solution A, stirring, and carrying out vacuum drying for 8h at 100 ℃ to obtain powder C;

(3) NaAlO in molar ratio₂、NaOH、H₂O = 1: 1.5: 10-14.7, mixing NaAlO₂Mixing NaOH and water uniformly, and marking as solution D; mix powder C and solution D and stir well until ready to use as solution E.

(4) Weighing a molecular sieve and a surfactant, wherein the surfactant is more than 1.5 times of the molecular sieve in mass, adding ethanol, and soaking the molecular sieve and the surfactant for more than 12 hours when ethanol liquid is required to submerge the molecular sieve and the surfactant; coarse filtering, taking solid, and marking as the soaked molecular sieve; drying is not required.

(5) Mixing the soaked molecular sieve with the solution E, stirring thoroughly, placing in a hydrothermal crystallization kettle, performing hydrothermal crystallization at 100-300 deg.C for 12-24 hr, filtering, and drying to obtain molecular sieve coated TiO₂The core-shell material of (1).

(6) And (3) immersing the core-shell material obtained in the step (5) into 0.001-3mol/L silver nitrate solution, placing the core-shell material under 365nm ultraviolet lamp irradiation for 5-10min, adding hexamethylenetetramine and 0.001-0.5mol/L silver nitrate solution, uniformly stirring, and placing the core-shell material into a crystallization kettle at the crystallization temperature of 90 ℃ for crystallization for 1 h.

The molecular sieve is preferably a hydrophobic molecular sieve; the hydrophobic molecular sieve is preferably a molecular sieve with methyl targeted positioning on a molecular sieve skeleton, and can be a commercially available hydrophobic molecular sieve or a self-made hydrophobic molecular sieve.

The method is characterized in that in the step (5), the addition amount of the soaked molecular sieve is 2-5 times of the mass of the powder C. The product obtained in step (5) still has hydrophobic properties, and the microporous or hierarchical pore structure of the molecular sieve is retained.

The surfactant is preferably one or two of stearic acid and sodium dodecyl benzene sulfonate.

In the scheme, the step (2) provides amorphous silicon for the step (4).

The soaking enables the surfactant to permeate into the pore structure of the molecular sieve, and the surfactant effectively improves the efficiency of the molecular sieve. And (3) providing more energy, ion charges and the like for preparing the core-shell structure material in the step (5) and removing indoor pollutants, so that the removing effect is obvious. The diatomite provides silicon element on one hand, and provides a small amount of Al2O3, Fe2O3, CaO and MgO on the other hand, so that the adsorption performance and the catalytic activity of the material are improved.

The prepared material is sprayed on the surface of a plate, furniture or home decoration to achieve the effect of removing indoor air pollutants.

The core-shell material designed and prepared by the invention forms the main component of the scavenger for removing indoor air pollutants. The catalytic material promotes electrons on an excited valence band to jump to a conduction band by a core-shell structure to form high-activity electrons with negative charges, further forms holes on the valence band, promotes photoelectrons to transfer, forms Schottky barriers for capturing the electrons from the outside, and effectively acts as electron traps to block the recombination of the electrons and the holes. When the enriched photoelectrons are captured by the oxidizing substances on the surface (such as formaldehyde and the like), electrons are continuously consumed in the process to cause energy level reduction, so that the photoelectrons can continuously flow to the surface of the material to keep Fermi level balance, and the photoelectron-hole recombination is reduced after the circulation, thereby enhancing the photocatalytic performance and leading the photoelectrons to have better absorption catalytic degradation performance in a visible light region.

Drawings

Fig. 1 is an SEM picture of example 1.

Detailed Description

The present invention will be described in further detail with reference to examples. The invention is not limited to the examples given.

Example 1

(1) Adding 150mL of 25% ammonia water into absolute ethyl alcohol at room temperature, mixing and stirring, adjusting the pH value to 7.5-8.2, adding 50g of titanium dioxide powder, and stirring for 30min to obtain a solution A;

(2) mixing 100mL of ethyl orthosilicate and 10mL of dimethyl diethoxysilane, and adding 25g of diatomite to obtain a solution B; quickly adding the solution B into the solution A, stirring, and carrying out vacuum drying for 8h at 100 ℃ to obtain powder C;

(3) NaAlO in molar ratio₂、NaOH、H₂O = 1: 1.5: 14.7, mixing NaAlO₂Mixing NaOH and water uniformly, and marking as solution D; mix powder C and solution D and stir well until ready to use as solution E.

(4) Weighing SAP0-34 molecular sieve with methyl modification 2 times of the powder C, weighing sodium dodecylbenzene sulfonate 1.5 times of the molecular sieve, adding ethanol to submerge the solid, stirring, and soaking the molecular sieve for more than 12 h; coarse filtering, taking solid, and marking as the soaked molecular sieve; drying is not required.

(5) Mixing the soaked molecular sieve with the solution E, stirring thoroughly, placing in a hydrothermal crystallization kettle, performing hydrothermal crystallization at 100-300 deg.C for 12-24 hr, filtering, and drying to obtain molecular sieve coated TiO ₂The core-shell material of (1).

(6) And (3) immersing the core-shell material obtained in the step (5) into 0.001mol/L silver nitrate solution, placing the core-shell material under 365nm ultraviolet lamp irradiation for 5-10min, adding hexamethylenetetramine and 0.001mol/L silver nitrate solution, uniformly stirring, placing the core-shell material into a crystallization kettle, and crystallizing at the crystallization temperature of 90 ℃ for 1h to obtain the target material.

Example 2

(1) Mixing 300mL of 25% ammonia water with absolute ethyl alcohol at room temperature, stirring, adjusting the pH value to 8-9, adding 100g of titanium dioxide powder, and stirring for 30min to obtain a solution A;

(2) mixing 50mL of ethyl orthosilicate and 10mL of dimethyl diethoxysilane, adding 40g of diatomite, and marking as a solution B; quickly adding the solution B into the solution A, stirring, and carrying out vacuum drying for 8h at 100 ℃ to obtain powder C;

(3) NaAlO in molar ratio₂、NaOH、H₂O = 1: 1.5: 10, mixing NaAlO₂Mixing NaOH and water uniformly, and marking as solution D; mix powder C and solution D and stir well until ready to use as solution E.

(4) Weighing 2 times of the mass of the powder C to obtain a SAP0-34 molecular sieve with methyl modification, weighing 2 times of the mass of the molecular sieve to obtain stearic acid, adding ethanol to submerge the solid, stirring, and soaking the molecular sieve for 48 h; coarse filtering, taking solid, and marking as the soaked molecular sieve; drying is not required.

(6) And (3) immersing the core-shell material obtained in the step (5) into 1mol/L silver nitrate solution, placing the core-shell material under 365nm ultraviolet lamp irradiation for 5-10min, adding hexamethylenetetramine and 1mol/L silver nitrate solution, uniformly stirring, placing the core-shell material in a crystallization kettle, and crystallizing at the crystallization temperature of 90 ℃ for 1h to obtain the target material.

Example 3

(1) Adding 150mL of 25% ammonia water into absolute ethyl alcohol at room temperature, mixing and stirring, adjusting the pH value to 7.5-8.5, adding 50g of titanium dioxide powder, and stirring for 30min to obtain a solution A;

(2) mixing 100mL of ethyl orthosilicate and 10mL of dimethyl diethoxysilane, and adding 100g of diatomite to obtain a solution B; quickly adding the solution B into the solution A, stirring, and carrying out vacuum drying for 8h at 100 ℃ to obtain powder C;

(4) Weighing a commercially available hydrophobic molecular sieve according to 2.5 times of the mass of the powder C, weighing sodium dodecyl benzene sulfonate according to 2 times of the mass of the weighed molecular sieve, adding ethanol, enabling ethanol liquid to submerge solids, stirring, and soaking the molecular sieve for 48 hours; coarse filtering, taking solid, and marking as the soaked molecular sieve; drying is not required.

(6) And (3) immersing the core-shell material obtained in the step (5) into 3mol/L silver nitrate solution, placing the core-shell material under 365nm ultraviolet lamp irradiation for 5-10min, adding hexamethylenetetramine and 3mol/L silver nitrate solution, uniformly stirring, placing the core-shell material into a crystallization kettle, and crystallizing at 90 ℃ for 1h to obtain the target material.

Other forms of the inventive arrangements. As explained in examples 4-5.

Example 4

(1) Mixing and stirring 100mL of 25% ammonia water and 200mL of ethanol at room temperature, and adjusting the pH value to 8-9, which is marked as solution A; mixing 50mL of ethyl orthosilicate and 10mL of dimethyldiethoxysilane, and marking as a solution B; the solution B was added rapidly to the solution A, stirred and dried under vacuum at 100 ℃.

(2) Commercially available hydrophobic SAP0-34 molecular sieves were purchased.

(3) NaAlO in molar ratio₂、NaOH、H₂O = 1: 1.5: 14.7, mixing NaAlO₂Uniformly mixing NaOH and water, adding a few drops of silver nitrate, wherein the addition amount of the silver nitrate accounts for four thousandths of the total volume of the solution and is recorded as solution C, adding the powder obtained in the step (1) and the hydrophobic molecular sieve obtained in the step (2) into the solution C, and fully stirring; crystallizing at 100 deg.C for 24 hr in a crystallization kettle, filtering, and drying to obtain target molecular sieve coated TiO ₂Containing amorphous siliconAnd Ag loading.

(4) And (3) placing the product dried in the step (3) into a 365nm ultraviolet lamp for irradiating for 5min, adding hexamethylenetetramine and 0.001M silver nitrate solution, uniformly stirring, placing into a crystallization kettle, and crystallizing at the crystallization temperature of 90 ℃ for 1h to obtain the target material.

Example 5

(1) Mixing and stirring 200mL of 25% ammonia water and 500mL of ethanol at room temperature, and adjusting the pH value to 8-9, which is marked as solution A; mixing 100mL of ethyl orthosilicate and 10mL of dimethyldiethoxysilane, and marking as a solution B; rapidly adding the solution B into the solution A, stirring, and carrying out vacuum drying at 100 ℃ to form amorphous silicon;

(2) si element is impregnated on the surface of the SAP0-34 molecular sieve with methyl modification by an impregnation method to form the hydrophobic SAP0-34 molecular sieve.

(3) NaAlO in molar ratio₂NaOH, H2O = 1: 1.5: 14.7, mixing NaAlO₂Uniformly mixing NaOH and water, recording as a solution C, adding the amorphous silicon obtained in the step (1) and the hydrophobic molecular sieve obtained in the step (2) into the solution C, and fully stirring; adding silver nitrate solution, wherein the addition amount of silver nitrate accounts for 20 percent of the total volume of the solution; crystallizing at 150 deg.C for 24 hr in a crystallization kettle, filtering, and drying to obtain target molecular sieve coated TiO ₂The core-shell material contains amorphous silicon and Ag load.

Fig. 1 is an SEM picture of example 1. As can be seen from FIG. 1, good crystallization effect is achieved, and regular nano-materials are prepared.

The material prepared by the embodiment is sprayed on the surface of a plate, furniture or home decoration to achieve the effect of removing indoor air pollutants. In the embodiment, the formaldehyde removal rate is over 95 percent, and the benzene and TVOC adsorption and degradation rates are over 85 percent. The prepared scavenger material has the advantages of retaining the hierarchical pore structure and the hydrophobicity of the molecular sieve and having good selective capture effect on organic matters.

Claims

1. A preparation method of a scavenger for efficiently degrading gaseous pollutants is characterized in that the main component of the scavenger is TiO₂Molecular sieve soaked with surfactant and Ag element; the scavenger is a core-shell structure; the core of the core-shell structure is mainly composed of TiO₂And amorphous silicon, the shell being a molecular sieve impregnated with a surfactant; the scavenger contains Al, Fe, Ca and Mg elements introduced by diatomite; the preparation method of the scavenger comprises the following steps:

(1) Mixing ammonia water and ethanol at room temperature, stirring, adjusting the pH value to be alkaline, adding titanium dioxide powder, stirring for 30min, and marking as a solution A;

(3) NaAlO in molar ratio₂、NaOH、H₂O = 1: 1.5: 10-14.7, mixing NaAlO₂Mixing NaOH and water uniformly, and marking as solution D; mixing the powder C and the solution D, and fully stirring for later use, and marking as a solution E;

(4) weighing a molecular sieve and a surfactant, wherein the surfactant is more than 1.5 times of the molecular sieve in mass, adding ethanol, and soaking the molecular sieve and the surfactant for more than 12 hours when ethanol liquid is required to submerge the molecular sieve and the surfactant; coarse filtering, taking solid, and marking as the soaked molecular sieve; drying is not needed;

(5) mixing the soaked molecular sieve with the solution E, stirring thoroughly, placing in a hydrothermal crystallization kettle, performing hydrothermal crystallization at 100-300 deg.C for 12-24 hr, filtering, and drying to obtain molecular sieve coated TiO₂The core-shell material of (1);

2. The method for preparing the scavenger for efficiently degrading gaseous pollutants according to claim 1, wherein the molecular sieve is preferably a hydrophobic molecular sieve; the method is characterized in that in the step (5), the addition amount of the soaked molecular sieve is 2-5 times of the mass of the powder C; the product obtained in step (5) still has hydrophobic properties, and the microporous or hierarchical pore structure of the molecular sieve is retained.

3. The method according to claim 1, wherein the surfactant is one or both of stearic acid and sodium dodecylbenzenesulfonate.

4. The method for preparing a scavenger for efficiently degrading gaseous pollutants according to claim 1, wherein the step (2) provides amorphous silicon for the step (4).

5. The method for preparing the scavenger for efficiently degrading the gaseous pollutants as claimed in claim 1, wherein the scavenger is rich in noble metal silver and is used for catalytically degrading formaldehyde, benzene and TVOC pollutants.