Activated carbon gel precursor particles with both dehumidification and deacetaldehyde functions and a preparation method thereof

Abstract

The present application belongs to the technical field of environmental remediation material preparation, and provides activated carbon gel precursor particles with both dehumidification and deacetaldehyde functions and a preparation method thereof. The present application first deposits a layer of manganese oxide catalyst on an activated carbon carrier in situ, solidifies a sodium alginate solution into initial gel microspheres by a liquid drop method; secondly, constructs a porous outer layer loaded with manganese oxide catalyst layer by layer through an alternating adsorption method of negative and positive polyelectrolytes, and carries out dehydration treatment on the microspheres through gradient solvent replacement; finally, grafts a layer of hydrophobic organosilane molecules on the outermost surface of the microspheres, and then obtains the precursor particles through vacuum drying. By placing the moisture absorption component and the catalytic component in different structural regions and hydrophobically modifying the surface of the particles, the mutual interference between the two functions is effectively avoided, so that the product can stably exert the dual functions of dehumidification and deacetaldehyde after moisture absorption, and at the same time has excellent storage stability.

Description

Technical Field

[0001] This invention belongs to the field of environmental remediation material preparation technology, and relates to an activated carbon gel precursor particle with both dehumidification and formaldehyde removal functions and its preparation method. Background Technology

[0002] Excessive humidity in living environments not only causes mold and damages items, but also poses a long-term threat to residents' health due to the continuous release of volatile organic compounds (VOCs) such as formaldehyde from building materials and furniture. Currently, various products are available on the market to improve indoor air quality. Traditional dehumidifiers often use hygroscopic salts to physically absorb moisture and reduce humidity, but the corrosive salt solutions produced after moisture absorption pose a risk of leakage and have limited functionality. In terms of formaldehyde removal, physical adsorbents such as activated carbon are limited in application due to their limited adsorption capacity and the risk of secondary release after saturation. Another type of chemical formaldehyde removal product, such as gels using formaldehyde scavengers, can react with formaldehyde, but they are consumable products with a short lifespan and cannot solve the humidity problem.

[0003] To meet market demand for multifunctional products, some gel or granule products have emerged that attempt to simply combine dehumidification and formaldehyde removal functions. However, these simple hybrid systems in existing technologies generally suffer from a difficult-to-overcome technical bottleneck: mutual inhibition and internal friction between the functions. Specifically, in humid environments, a large number of water molecules compete with formaldehyde molecules for the active sites of catalysts or adsorbents, significantly reducing formaldehyde removal efficiency. At the same time, the liquid environment formed after the desiccant absorbs moisture may also encapsulate, dilute, or even cause the degradation or inactivation of the formaldehyde-removing active ingredients. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions, and a method for their preparation. First, activated carbon loaded with a manganese oxide catalyst is prepared and used as the main formaldehyde removal component. A gel microsphere core containing highly hygroscopic salts is prepared using a droplet method. Then, a stable shell loaded with the catalyst is constructed on the surface of this core using a layer-by-layer self-assembly technique. The outermost layer is then hydrophobically modified to effectively isolate the moisture absorption unit from the formaldehyde removal unit, avoiding interference from moisture on catalytic activity, thus meeting the needs of actual production.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions, the preparation method comprising:

[0007] S1, activated carbon is added to MES (2-(N-morpholino)ethanesulfonic acid) buffer solution, and potassium permanganate solution is added dropwise to the MES buffer solution to react and obtain MnO. X @AC powder, the MnO X Including MnO2, MnOOH and Mn3O4;

[0008] S2, sodium alginate solution is dropped into calcium chloride curing solution, and then transferred to calcium chloride solution for curing to obtain core microspheres. The core microspheres are then sequentially immersed in shell layer A solution and shell layer B solution for assembly to obtain layered microspheres. The layered microspheres are then transferred to crosslinking solution for crosslinking at room temperature in the dark, and then placed in ethanolamine solution for end-capping to obtain crosslinked microspheres. The crosslinking solution is an aqueous solution of 2-morpholinoethanesulfonic acid, 1-(3-dimethylaminopropyl)-3-ethylcarboimide and N-hydroxysuccinimide.

[0009] S3. The cross-linked microspheres are subjected to gradient solvent replacement. After the replacement is completed, they are transferred to hydrolysate and then to condensation solution to obtain activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions.

[0010] Specifically, it includes:

[0011] S1, add activated carbon to MES buffer solution, and at the first temperature, add potassium permanganate solution dropwise to the MES buffer solution to react. Filter while hot, wash with hot deionized water until the filtrate is colorless, and dry to obtain MnO. X @AC powder, the MnO X Including MnO2, MnOOH and Mn3O4;

[0012] S2, sodium alginate solution is dropped into calcium chloride curing solution, then transferred to calcium chloride solution for curing at a second temperature, and then washed with deionized water to obtain core microspheres. The core microspheres are then sequentially immersed in shell layer A solution and shell layer B solution for assembly to obtain layered microspheres. The layered microspheres are then transferred to crosslinking solution for crosslinking at room temperature in the dark, and then placed in ethanolamine solution for end capping and washed with deionized water to obtain crosslinked microspheres. The crosslinking solution is an aqueous solution of 2-morpholinoethanesulfonic acid, 1-(3-dimethylaminopropyl)-3-ethylcarboimide and N-hydroxysuccinimide.

[0013] S3, cross-linked microspheres are subjected to gradient solvent replacement. After replacement, they are transferred to a hydrolysate and hydrolyzed at a second temperature. Then, they are transferred to a condensation solution and condensed at a third temperature. After washing with anhydrous ethanol, they are vacuum dried to obtain activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions.

[0014] In S1, potassium permanganate, as a strong oxidant, reacts with activated carbon, as a reducing agent, in an aqueous buffer system to undergo a redox reaction. The heptavalent manganese in the permanganate ion is reduced by carbon atoms or oxygen-containing functional groups on the surface of activated carbon to generate manganese oxides in various valence states, mainly tetravalent manganese oxides. The newly generated manganese oxides are deposited in situ in the form of nanoparticles and anchored in the huge inner and outer surfaces and pores of activated carbon to form a supported catalyst.

[0015] In step S2, a solution containing sodium alginate is dropped into a calcium chloride curing solution. The carboxylate anions on the sodium alginate molecular chains undergo an ion exchange reaction with the divalent calcium ions provided by calcium chloride. Calcium ions act as crosslinking agents, simultaneously coordinating with the carboxyl groups on two or more alginate chains, causing sodium alginate to rapidly transform from a soluble state into a water-insoluble three-dimensional network gel, thus forming a spherical hydrogel core. The subsequent curing process promotes chain rearrangement and further crosslinking within the gel network, enhancing its mechanical strength and structural regularity. Next, the shell is constructed through a layer-by-layer self-assembly process based on electrostatic interactions. The surface of the core microspheres carries a negative charge due to the adsorption of alginate chains. Immersing it in a positively charged chitosan solution, a layer of chitosan is adsorbed through electrostatic attraction. The amine groups on the chitosan molecular chains protonate under acidic conditions, becoming positively charged. After washing away the unadsorbed chitosan, the microspheres are immersed in a suspension containing negatively charged sodium alginate and manganese oxide catalyst particles. The positively charged surfaces then adsorb these negatively charged components. By repeatedly immersing the microspheres in these two polyelectrolyte solutions with opposite charges, a multilayer film structure consisting of alternating alginate and chitosan particles, encapsulating the catalyst particles, is constructed layer by layer on the core surface. To enhance the stability of this multilayer film, a chemical cross-linking method is employed. 1-(3-dimethylaminopropyl)-3-ethylcarboimide first activates the carboxyl group of sodium alginate, forming an active O-acylisourea intermediate. This intermediate is unstable and is subsequently captured by N-hydroxysuccinimide, generating a relatively stable NHS (N-hydroxysuccinimide ester) active ester. The active ester can efficiently undergo a nucleophilic acyl substitution reaction with the primary amine groups on the chitosan molecular chain, forming a stable amide bond.

[0016] In S3, a gradient solvent replacement process is first performed. By gradually increasing the ethanol concentration, water molecules in the gel network are replaced with ethanol molecules. The addition of glycerol acts as a humectant and osmotic pressure regulator, further buffering the dehydration stress during the initial replacement phase. After the replacement is complete, a two-step silanization reaction is carried out. In the first hydrolysis stage, hexadecyltrimethoxysilane undergoes methoxylysis under acid catalysis and in the presence of trace amounts of water, generating reactive silanol groups. In the second condensation stage, the system becomes alkaline, and alkaline catalysis promotes two reactions: first, dehydration condensation between silanol groups forms siloxane bonds, creating an oligomeric or polymeric siloxane network on the particle surface; second, under conditions that reduce free water and promote interfacial reactions on the microsphere surface, silanol groups undergo dehydration condensation with the hydroxyl or carboxyl groups on the surface of the outermost polymer layer of the gel (such as chitosan or alginate), forming covalent bonds. This anchors the siloxane network with long hexadecyl hydrophobic chains to the microsphere surface, ultimately yielding dry, porous precursor particles.

[0017] As a preferred technical solution of the present invention, in S1, the mass ratio of activated carbon, MES buffer solution and potassium permanganate solution is (5-6):(200-210):200, for example, it can be (5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9 or 6.0):(200, 201, 202, 203, 204, 205, 206, 207, 208, 209 or 210):200, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0018] In some optional embodiments, the concentration of the MES buffer is 10-15 mmol / L.

[0019] In some alternative embodiments, the first temperature is 60-65°C, for example, it can be 60°C, 60.5°C, 61°C, 61.5°C, 62°C, 62.5°C, 63°C, 63.5°C, 64°C, 64.5°C or 65°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0020] In some optional embodiments, the concentration of the potassium permanganate solution is 0.1 mol / L.

[0021] In some optional embodiments, the dropping rate is 1 g / min.

[0022] In some alternative embodiments, the reaction time is 3.5-4 hours, for example, 3.5 hours, 3.55 hours, 3.6 hours, 3.65 hours, 3.7 hours, 3.75 hours, 3.8 hours, 3.85 hours, 3.9 hours, 3.95 hours, or 4.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0023] As a preferred technical solution of the present invention, in S2, the mass ratio of sodium alginate solution, calcium chloride curing liquid and calcium chloride solution is (100-110):1000:1000, for example (100, 101, 102, 103, 104, 105, 106, 107, 108, 109 or 110):1000:1000, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] In some optional embodiments, the sodium alginate solution has a mass fraction of 2 wt.%.

[0025] In some optional embodiments, the dripping rate is 20 g / h.

[0026] In some optional embodiments, the mass fraction of the calcium chloride curing solution is 30-32 wt.%, for example, it can be 30 wt.%, 30.2 wt.%, 30.4 wt.%, 30.6 wt.%, 30.8 wt.%, 31.0 wt.%, 31.2 wt.%, 31.4 wt.%, 31.6 wt.%, 31.8 wt.%, or 32 wt.%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0027] In some optional embodiments, the mass fraction of the calcium chloride solution is 10-12 wt.%, for example, it can be 10 wt.%, 10.2 wt.%, 10.4 wt.%, 10.6 wt.%, 10.8 wt.%, 11.0 wt.%, 11.2 wt.%, 11.4 wt.%, 11.6 wt.%, 11.8 wt.%, or 12 wt.%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0028] In some alternative embodiments, the second temperature is 40-45°C, for example, it can be 40°C, 40.5°C, 41°C, 41.5°C, 42°C, 42.5°C, 43°C, 43.5°C, 44°C, 44.5°C or 45°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0029] In some optional embodiments, the curing time is 2-2.5 hours, for example, 2.0 hours, 2.05 hours, 2.1 hours, 2.15 hours, 2.2 hours, 2.25 hours, 2.3 hours, 2.35 hours, 2.4 hours, 2.45 hours or 2.5 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] In some optional embodiments, the shell layer A solution is prepared by dissolving (1-1.5) g of chitosan in 100 g of a 1 wt.% aqueous acetic acid solution, and adjusting the pH to 4.5-5 using a 0.1 mol / L aqueous acetic acid solution. For example, it could be: dissolving (1.0, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, or 1.5) g of chitosan in 100 g of a 1 wt.% aqueous acetic acid solution, and adjusting the pH to (4.5, 4.55, 4.6, 4.65, 4.7, 4.75, 4.8, 4.85, 4.9, 4.95, or 5.0) using a 0.1 mol / L aqueous acetic acid solution, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0031] In some optional embodiments, the shell layer B solution is prepared by: adding (2-2.5) g MnO X @AC powder is dispersed in 100g of 10mmol / L NaCl solution and sonicated for 15-20min. 1g of sodium alginate is then added. The shell layer B solution is sonicated for 5min before use. For example, it could be: (2.0, 2.05, 2.1, 2.15, 2.2, 2.25, 2.3, 2.35, 2.4, 2.45, or 2.5)g of MnO X @AC powder is dispersed in 100g of 10mmol / L NaCl solution and sonicated for (15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5 or 20) min. 1g of sodium alginate is added. The shell B solution is sonicated for 5 min before use, but it is not limited to the values ​​listed. Other unlisted values ​​within this range are also applicable.

[0032] In some optional embodiments, the assembly procedure is as follows: the core microspheres are adsorbed in shell solution A for 15 minutes and then washed with deionized water, then placed in shell solution B for 15 minutes and washed with deionized water. This step is counted as one cycle, and a total of 8 cycles are performed.

[0033] In some optional embodiments, the crosslinking solution contains 0.1 mol / L of 2-morpholinoethanesulfonic acid, 50 mmol / L of 1-(3-dimethylaminopropyl)-3-ethylcarboimide, 25 mmol / L of N-hydroxysuccinimide, and has a pH of 6-6.5.

[0034] In some optional embodiments, the solid-liquid mass ratio of the layered microspheres to the crosslinking liquid is not higher than 1:20.

[0035] In some optional embodiments, the solid-liquid mass ratio of the layered microspheres to the ethanolamine solution is not higher than 1:20.

[0036] In some optional embodiments, the light-protected crosslinking time is 4-5 hours, for example, 4.0 hours, 4.1 hours, 4.2 hours, 4.3 hours, 4.4 hours, 4.5 hours, 4.6 hours, 4.7 hours, 4.8 hours, 4.9 hours, or 5.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0037] In some optional embodiments, the concentration of the ethanolamine solution is 0.1 mol / L.

[0038] In some optional embodiments, the sealing time is 1-1.5h, for example, it can be 1.0h, 1.05h, 1.1h, 1.15h, 1.2h, 1.25h, 1.3h, 1.35h, 1.4h, 1.45h or 1.5h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0039] As a preferred embodiment of the present invention, in step S3, the gradient solvent replacement includes the following steps:

[0040] A1, a mixed solvent of anhydrous ethanol, glycerol and deionized water is used for displacement, and the displacement time is 60-65 min. The mass ratio of anhydrous ethanol, glycerol and deionized water in the mixed solvent is 25:1:74.

[0041] A2, use a 50 wt.% ethanol solution for replacement, the replacement time is 60-65 min;

[0042] A3, use 75wt.% ethanol solution for replacement, the replacement time is 30-35min;

[0043] A4, use 95wt.% ethanol solution for replacement, the replacement time is 30-35min;

[0044] A5, use anhydrous ethanol for replacement, the replacement time is 30-35 min.

[0045] In some optional embodiments, the hydrolysate is prepared by dissolving hexadecyltrimethoxysilane in a 50 wt.% aqueous ethanol solution, wherein the pH of the aqueous ethanol solution is adjusted to 4.5-5 with glacial acetic acid, and the mass ratio of hexadecyltrimethoxysilane to the ethanol solution is 5:95.

[0046] In some optional embodiments, the stirring hydrolysis time is 2-3 hours, for example, 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3.0 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] In some optional embodiments, the condensate is a mixed solution of anhydrous ethanol and triethylamine, wherein the mass ratio of anhydrous ethanol to triethylamine is 99.8:0.2.

[0048] In some alternative embodiments, the third temperature is 50-55°C, for example, it can be 50°C, 50.5°C, 51°C, 51.5°C, 52°C, 52.5°C, 53°C, 53.5°C, 54°C, 54.5°C or 55°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0049] In some optional embodiments, the third temperature condensation time is 1.5-2 hours, for example, it can be 1.5 hours, 1.55 hours, 1.6 hours, 1.65 hours, 1.7 hours, 1.75 hours, 1.8 hours, 1.85 hours, 1.9 hours, 1.95 hours or 2.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0050] In some optional embodiments, the solid-liquid mass ratio of the cross-linked microspheres to the gradient solvent is not higher than 1:20.

[0051] In some optional embodiments, the solid-liquid mass ratio of the cross-linked microspheres to the hydrolysate is not higher than 1:20.

[0052] In some optional embodiments, the solid-liquid mass ratio of the cross-linked microspheres to the condensation liquid is not higher than 1:20.

[0053] In some optional embodiments, the vacuum drying is performed by drying at 40°C for 4 hours under vacuum conditions, followed by drying at 60°C for 8 hours.

[0054] Secondly, the present invention provides an activated carbon gel precursor particle with both dehumidification and formaldehyde removal functions, prepared by the preparation method described in the first aspect.

[0055] Compared with existing technologies, the beneficial effects of this invention are as follows: Firstly, through a multi-layered structural design, the highly hygroscopic core and the catalyst-supported shell are effectively isolated spatially, solving the problems of moisture competing with formaldehyde molecules for adsorption sites and catalyst deactivation caused by the liquid environment after moisture absorption in traditional composite products. Secondly, by modifying the outermost layer of the particles with hydrophobicity, the risk of particles sticking together during moisture absorption is reduced, ensuring the overall air permeability and air contact area of ​​the product, thereby improving its comprehensive purification efficiency and user experience. Thirdly, this invention prepares a dry precursor particle with extremely low water activity, giving the product excellent shelf-life stability, effectively preventing microbial growth and degradation of active ingredients during storage, and greatly extending the product's effective service life. Simultaneously, the dry and lightweight form greatly facilitates product packaging, storage, and transportation. Detailed Implementation

[0056] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0057] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone any further purification treatment.

[0058] Example 1

[0059] This embodiment provides activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions, and a method for preparing the same. The preparation method specifically includes the following steps:

[0060] S1, 5g of activated carbon was added to 210g of 10mmol / L MES buffer. At 60°C, 200.00g of 0.1mol / L potassium permanganate solution was added dropwise to the MES buffer at a rate of 1g / min for 4 hours. The mixture was then filtered while hot, washed with hot deionized water until the filtrate was colorless, and dried to obtain MnO. X @AC powder, the MnO X Including MnO2, MnOOH and Mn3O4;

[0061] S2, 100g of a 2wt.% sodium alginate solution was added dropwise to 1000g of a 32wt.% calcium chloride curing solution at a rate of 20g / h, followed by 1000g of a 10wt.% calcium chloride solution and curing at 45°C for 2h. The microspheres were then washed with deionized water to obtain the core microspheres. These core microspheres were then sequentially immersed in shell solution A and shell solution B for assembly. Shell solution A was prepared by dissolving 1.5g of chitosan in 100g of a 1wt.% acetic acid aqueous solution and adjusting the pH to 4.5 using a 0.1mol / L acetic acid aqueous solution. Shell solution B was prepared by dissolving 2g of MnO... X @AC powder was dispersed in 100g of 10mmol / L NaCl solution and sonicated for 20min. 1g of sodium alginate was added. The shell layer B solution was sonicated for 5min before use. The assembly procedure was as follows: the core microspheres were adsorbed in shell layer A solution for 15min and then washed with deionized water. Then, they were placed in shell layer B solution for 15min and washed with deionized water. This step was counted as one cycle. A total of 8 cycles were performed to obtain layered microspheres. The layered microspheres were then transferred to a crosslinking solution for crosslinking at room temperature in the dark. After 5 hours, the concentration of 2-morpholinoethanesulfonic acid in the crosslinking solution was 0.1 mol / L, the concentration of 1-(3-dimethylaminopropyl)-3-ethylcarboimide was 50 mmol / L, the concentration of N-hydroxysuccinimide was 25 mmol / L, and the pH of the crosslinking solution was 6. The solution was then capped with 0.1 mol / L ethanolamine solution for 1 hour. The solid-liquid mass ratio of the layered microspheres to the crosslinking solution was 1:20, and the solid-liquid mass ratio of the layered microspheres to the ethanolamine solution was 1:20. The microspheres were washed with deionized water to obtain crosslinked microspheres.

[0062] S3, the cross-linked microspheres are subjected to gradient solvent replacement, which includes the following steps: A1, replacement is performed using a mixed solvent of anhydrous ethanol, glycerol, and deionized water for 60 min, wherein the mass ratio of anhydrous ethanol, glycerol, and deionized water in the mixed solvent is 25:1:74; A2, replacement is performed using a 50 wt.% ethanol solution for 60 min; A3, replacement is performed using a 75 wt.% ethanol solution for 30 min; A4, replacement is performed using a 95 wt.% ethanol solution for 30 min; A5, replacement is performed using anhydrous ethanol for 30 min; after replacement, the microspheres are transferred to a hydrolysate, which is prepared by dissolving hexadecyltrimethoxysilane in 50 wt.% ethanol solution. A 0.5% ethanol-water solution, wherein the pH of the ethanol-water solution is adjusted to 4.6 with glacial acetic acid, and the mass ratio of hexadecyltrimethoxysilane to the ethanol solution is 5:95, is hydrolyzed at 40°C for 3 hours with stirring, and then transferred to a condensation solution and condensed at 55°C for 1.5 hours. The condensation solution is a mixed solution of anhydrous ethanol and triethylamine, wherein the mass ratio of anhydrous ethanol to triethylamine is 99.8:0.2. The solid-liquid mass ratio of the cross-linked microspheres to the gradient solvent is 1:20, the solid-liquid mass ratio of the cross-linked microspheres to the hydrolysate is 1:20, and the solid-liquid mass ratio of the cross-linked microspheres to the condensation solution is 1:20. After washing with anhydrous ethanol, it is vacuum dried at 40°C for 4 hours under vacuum, and then heated to 60°C for 8 hours to obtain an activated carbon gel precursor particle with both dehumidification and formaldehyde removal functions.

[0063] Example 2

[0064] This embodiment provides activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions, and a method for preparing the same. The preparation method specifically includes the following steps:

[0065] S1, 6g of activated carbon was added to 200g of 15mmol / L MES buffer. At 65°C, 200.00g of 0.1mol / L potassium permanganate solution was added dropwise to the MES buffer at a rate of 1g / min for 3.5h. The mixture was then filtered while hot, washed with hot deionization solution until the filtrate was colorless, and dried to obtain MnO. X @AC powder, the MnO X Including MnO2, MnOOH and Mn3O4;

[0066] S2, 110g of a 2wt.% sodium alginate solution was added dropwise to 1000g of a 30wt.% calcium chloride curing solution at a rate of 20g / h, followed by 1000g of a 12wt% calcium chloride solution and curing at 40°C for 2.5h. The microspheres were then washed with deionized water to obtain the core microspheres. These core microspheres were then sequentially immersed in shell solution A and shell solution B for assembly. Shell solution A was prepared by dissolving 1g of chitosan in 100g of a 1wt.% acetic acid aqueous solution and adjusting the pH to 5 using a 0.1mol / L acetic acid aqueous solution. Shell solution B was prepared by dissolving 2.5g of MnO... X @AC powder was dispersed in 100g of 10mmol / L NaCl solution and sonicated for 15min. 1g of sodium alginate was added. The shell layer B solution was sonicated for 5min before use. The assembly procedure was as follows: the core microspheres were adsorbed in shell layer A solution for 15min and then washed with deionized water. They were then placed in shell layer B solution for adsorption for 15min and washed with deionized water. This step was counted as one cycle, and a total of 8 cycles were performed to obtain layered microspheres. The layered microspheres were then transferred to a crosslinking solution and crosslinked at room temperature in the dark for 4 minutes. h, the concentration of 2-morpholinoethanesulfonic acid in the crosslinking solution is 0.1 mol / L, the concentration of 1-(3-dimethylaminopropyl)-3-ethylcarboimide is 50 mmol / L, the concentration of N-hydroxysuccinimide is 25 mmol / L, the pH of the crosslinking solution is 6, and then it is sealed in 0.1 mol / L ethanolamine solution for 1.5 h. The solid-liquid mass ratio of the layered microspheres to the crosslinking solution is 1:22, and the solid-liquid mass ratio of the layered microspheres to the ethanolamine solution is 1:22. After washing with deionized water, crosslinked microspheres are obtained.

[0067] S3, the cross-linked microspheres are subjected to gradient solvent replacement: A1, replacement is performed using a mixed solvent of anhydrous ethanol, glycerol, and deionized water for 65 min, wherein the mass ratio of anhydrous ethanol, glycerol, and deionized water in the mixed solvent is 25:1:74; A2, replacement is performed using a 50 wt.% ethanol solution for 65 min; A3, replacement is performed using a 75 wt.% ethanol solution for 35 min; A4, replacement is performed using a 95 wt.% ethanol solution for 35 min; A5, replacement is performed using anhydrous ethanol for 35 min. After replacement, the microspheres are transferred to a hydrolysate, which is prepared by dissolving hexadecyltrimethoxysilane in a 50 wt.% ethanol aqueous solution. The ethanol-water solution was adjusted to pH 4.7 with glacial acetic acid. The mass ratio of hexadecyltrimethoxysilane to the ethanol solution was 5:95. The solution was hydrolyzed at 45°C for 2 hours with stirring, and then transferred to a condensation solution at 50°C for 2 hours. The condensation solution was a mixture of anhydrous ethanol and triethylamine with a mass ratio of 99.8:0.2. The solid-liquid mass ratio of the cross-linked microspheres to the gradient solvent was 1:22. The solid-liquid mass ratio of the cross-linked microspheres to the hydrolysate was 1:22. The solid-liquid mass ratio of the cross-linked microspheres to the condensation solution was 1:22. After washing with anhydrous ethanol, the solution was vacuum dried at 40°C for 4 hours under vacuum, and then dried at 60°C for 8 hours to obtain activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions.

[0068] Example 3

[0069] This embodiment provides activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions, and a method for preparing the same. The preparation method specifically includes the following steps:

[0070] S1, 5.5 g of activated carbon was added to 205 g of 12 mmol / L MES buffer. At 62°C, 200.00 g of 0.1 mol / L potassium permanganate solution was added dropwise to the MES buffer at a rate of 1 g / min for 3.8 h. The mixture was then filtered while hot, washed with hot deionization solution until the filtrate was colorless, and dried to obtain MnO. X @AC powder, the MnO X Including MnO2, MnOOH and Mn3O4;

[0071] S2, 105g of a 2wt.% sodium alginate solution was added dropwise to 1000g of a 31wt.% calcium chloride curing solution at a rate of 20g / h, followed by 1000g of an 11wt% calcium chloride solution and curing at 42°C for 2.2h. The microspheres were then washed with deionized water to obtain the core microspheres. These core microspheres were then sequentially immersed in shell solution A and shell solution B for assembly. Shell solution A was prepared by dissolving 1.2g of chitosan in 100g of a 1wt.% acetic acid aqueous solution and adjusting the pH to 4.8 using a 0.1mol / L acetic acid aqueous solution. Shell solution B was prepared by dissolving 2.2g of MnO... X @AC powder was dispersed in 100g of 10mmol / L NaCl solution and sonicated for 18min. 1g of sodium alginate was added. The shell layer B solution was sonicated for 5min before use. The assembly procedure was as follows: the core microspheres were adsorbed in the shell layer A solution for 15min and then washed with deionized water. Then, they were placed in the shell layer B solution for adsorption for 15min and washed with deionized water. This step was counted as one cycle. A total of 8 cycles were performed to obtain layered microspheres. The layered microspheres were then transferred to a crosslinking solution and crosslinked at room temperature in the dark for 4 minutes. After 5 hours, the concentration of 2-morpholinoethanesulfonic acid in the crosslinking solution was 0.1 mol / L, the concentration of 1-(3-dimethylaminopropyl)-3-ethylcarboimide was 50 mmol / L, the concentration of N-hydroxysuccinimide was 25 mmol / L, and the pH of the crosslinking solution was 6. The solution was then capped with 0.1 mol / L ethanolamine solution for 1.2 hours. The solid-liquid mass ratio of the layered microspheres to the crosslinking solution was 1:24. The microspheres were washed with deionized water to obtain the crosslinked microspheres.

[0072] S3, the cross-linked microspheres are subjected to gradient solvent replacement, which includes the following steps: A1, replacement is performed using a mixed solvent of anhydrous ethanol, glycerol, and deionized water for 62 min, wherein the mass ratio of anhydrous ethanol, glycerol, and deionized water in the mixed solvent is 25:1:74; A2, replacement is performed using a 50 wt.% ethanol solution for 64 min; A3, replacement is performed using a 75 wt.% ethanol solution for 33 min; A4, replacement is performed using a 95 wt.% ethanol solution for 31 min; A5, replacement is performed using anhydrous ethanol for 30 min; after replacement, the microspheres are transferred to a hydrolysate, which is prepared by dissolving hexadecyltrimethoxysilane in 50 wt.% ethanol solution. A 0.5% ethanol aqueous solution, wherein the pH of the ethanol aqueous solution is adjusted to 5 with glacial acetic acid, and the mass ratio of hexadecyltrimethoxysilane to the ethanol solution is 5:95, is stirred and hydrolyzed at 42°C for 2.5 h, and then transferred to a condensation solution and condensed at 52°C for 1.8 h. The condensation solution is a mixed solution of anhydrous ethanol and triethylamine, wherein the mass ratio of anhydrous ethanol to triethylamine is 99.8:0.2. The solid-liquid mass ratio of the cross-linked microspheres to the gradient solvent is 1:24, the solid-liquid mass ratio of the cross-linked microspheres to the hydrolysate is 1:24, and the solid-liquid mass ratio of the cross-linked microspheres to the condensation solution is 1:24. After washing with anhydrous ethanol, it is vacuum dried at 40°C for 4 h under vacuum conditions, and then heated to 60°C for 8 h to obtain an activated carbon gel precursor particle with both dehumidification and formaldehyde removal functions.

[0073] Example 4

[0074] This embodiment provides activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions, and a method for preparing the same. The preparation method specifically includes the following steps:

[0075] S1, 5.2 g of activated carbon was added to 208 g of 14 mmol / L MES buffer. At 64°C, 200.00 g of 0.1 mol / L potassium permanganate solution was added dropwise to the MES buffer at a rate of 1 g / min for 3.6 h. The mixture was then filtered while hot, washed with hot deionization solution until the filtrate was colorless, and dried to obtain MnO. X @AC powder, the MnO X Including MnO2, MnOOH and Mn3O4;

[0076] S2, 108g of a 2wt.% sodium alginate solution was added dropwise to 1000g of a 31.5wt.% calcium chloride curing solution at a rate of 20g / h, followed by 1000g of a 10.5wt% calcium chloride solution and curing at 44°C for 2.4h. The microspheres were then washed with deionized water to obtain the core microspheres. These core microspheres were then sequentially immersed in shell solution A and shell solution B for assembly. Shell solution A was prepared by dissolving 1.4g of chitosan in 100g of a 1wt.% acetic acid aqueous solution and adjusting the pH to 4.6 using a 0.1mol / L acetic acid aqueous solution. Shell solution B was prepared by dissolving 2.4g of MnO... X @AC powder was dispersed in 100g of 10mmol / L NaCl solution and sonicated for 16min. 1g of sodium alginate was added. The shell layer B solution was sonicated for 5min before use. The assembly procedure was as follows: the core microspheres were adsorbed in the shell layer A solution for 15min and then washed with deionized water. Then, they were placed in the shell layer B solution for adsorption for 15min and washed with deionized water. This step was counted as one cycle. A total of 8 cycles were performed to obtain layered microspheres. The layered microspheres were then transferred to a crosslinking solution and crosslinked at room temperature in the dark for 4 minutes. After 2 hours, the concentration of 2-morpholine ethanesulfonic acid in the crosslinking solution was 0.1 mol / L, the concentration of 1-(3-dimethylaminopropyl)-3-ethylcarboimide was 50 mmol / L, the concentration of N-hydroxysuccinimide was 25 mmol / L, and the pH of the crosslinking solution was 6. The solution was then capped with 0.1 mol / L ethanolamine solution for 1.4 hours. The solid-liquid mass ratio of the layered microspheres to the crosslinking solution was 1:25, and the solid-liquid mass ratio of the layered microspheres to the ethanolamine solution was 1:25. The microspheres were washed with deionized water to obtain crosslinked microspheres.

[0077] S3, the cross-linked microspheres are subjected to gradient solvent replacement, which includes the following steps: A1, replacement is performed using a mixed solvent of anhydrous ethanol, glycerol, and deionized water for 61 min, wherein the mass ratio of anhydrous ethanol, glycerol, and deionized water in the mixed solvent is 25:1:74; A2, replacement is performed using a 50 wt.% ethanol solution for 62 min; A3, replacement is performed using a 75 wt.% ethanol solution for 33 min; A4, replacement is performed using a 95 wt.% ethanol solution for 34 min; A5, replacement is performed using anhydrous ethanol for 30 min; after replacement, the microspheres are transferred to a hydrolysate, which is prepared by dissolving hexadecyltrimethoxysilane in 50 wt.% ethanol solution. A % ethanol-water solution, wherein the pH of the ethanol-water solution is adjusted to 4.5 with glacial acetic acid, and the mass ratio of hexadecyltrimethoxysilane to the ethanol solution is 5:95, is stirred and hydrolyzed at 41°C for 2.8 h, and then transferred to a condensation solution and condensed at 54°C for 1.6 h. The condensation solution is a mixed solution of anhydrous ethanol and triethylamine, wherein the mass ratio of anhydrous ethanol to triethylamine is 99.8:0.2. The solid-liquid mass ratio of the cross-linked microspheres to the gradient solvent is 1:25, the solid-liquid mass ratio of the cross-linked microspheres to the hydrolysate is 1:25, and the solid-liquid mass ratio of the cross-linked microspheres to the condensation solution is 1:25. After washing with anhydrous ethanol, it is vacuum dried at 40°C for 4 h under vacuum conditions, and then heated to 60°C for 8 h to obtain an activated carbon gel precursor particle with both dehumidification and formaldehyde removal functions.

[0078] Comparative Example 1

[0079] This comparative example provides activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions and their preparation method. The difference between this and Example 1 is that it does not use the ordered stepwise construction method in S2, but instead uses a co-curing method to prepare microspheres. Specifically, the sodium alginate solution used in Example 1 for preparing the core is combined with the MnO-containing solution used for preparing the shell. X @AC powder and sodium alginate suspension were dripped into calcium chloride curing solution at the same speed through a coaxial dual-channel nozzle for co-curing into spheres. Then, only cleaning and vacuum drying were performed. Assembly procedures, chemical crosslinking, functional group end-capping and surface hydrophobic modification were not performed. Other process parameters and operating conditions that were not replaced in the co-curing method were the same as the corresponding parts of Example 1.

[0080] Comparative Example 2

[0081] This comparative example provides activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions and their preparation method. The difference between this example and Example 1 is that the chemical cross-linking and curing step in S2 is omitted. Specifically, after obtaining the layered microspheres in the assembly process, the cross-linking step of transferring to the cross-linking solution and the subsequent ethanolamine solution end-capping step are not performed. Instead, the uncross-linked layered microspheres are directly subjected to gradient solvent replacement in S3 and all subsequent steps. Other process parameters and operating conditions are exactly the same as in Example 1.

[0082] Comparative Example 3

[0083] This comparative example provides activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions and their preparation method. The difference between this example and Example 1 is that the step of hydrophobic modification of the particle surface is omitted in S3. Specifically, after obtaining cross-linked microspheres in S2 and completing the gradient solvent replacement in S3, the entire silanization modification process of transferring to hydrolysate and then transferring to condensation solution for condensation is not performed. Instead, the microspheres after gradient solvent replacement are directly subjected to the final vacuum drying step. Other process parameters and operating conditions are exactly the same as in Example 1.

[0084] The performance of the activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions prepared in Examples 1-4 and Comparative Examples 1-3 was tested. The specific process is as follows:

[0085] Dehumidification performance test method: 2.000g of the dry granular sample to be tested was evenly spread on the bottom of an open glass weighing bottle that had been pre-equilibrated in a constant temperature and humidity chamber at 25℃ and 80% relative humidity (RH) for 12 hours and had already been weighed. The initial total mass m0 was quickly weighed and recorded. The sample bottle was then placed open in the constant temperature and humidity chamber at 25℃ and 80% RH. At the 24th hour, the sample bottle was quickly removed, weighed on an analytical balance, and its total mass m1 was recorded. Moisture absorption rate (24h) = [(m1–m0) / m0] × 100%. Simultaneously, an empty weighing bottle was placed under the same conditions as a blank control to correct for possible environmental fluctuations.

[0086] Test method for formaldehyde removal performance against humidity interference: Place 1m 3 A clean, airtight stainless steel test chamber was placed at 25°C, and its internal relative humidity was adjusted to 50%RH (low humidity condition) and 80%RH (high humidity condition), respectively. A small fan was pre-installed inside the chamber to ensure uniform gas mixing. Formaldehyde sources were injected under each humidity condition to stabilize the initial formaldehyde concentration at 1.0 mg / m³. 3The fan was turned on for 5-10 minutes to circulate the air. The initial concentration C0 was measured and recorded using an online formaldehyde analyzer. 20.0g of the dry granular sample was spread evenly in a petri dish, quickly placed in the test chamber, and immediately sealed. The sample was then statically placed under the appropriate temperature and humidity conditions for 4 hours. After this, the fan was turned on for 2-3 minutes to ensure uniform gas mixing, and the final concentration C1 was measured and recorded. Formaldehyde removal rate (4h) = [(C0–C1) / C0] × 100%. The formaldehyde removal rate of the sample under two humidity conditions was compared to evaluate its resistance to humidity interference.

[0087] The test results are shown in Table 1.

[0088]

[0089] Table 1. Performance test results of activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions prepared in Examples 1-4 and Comparative Examples 1-3.

[0090] As shown in Table 1, compared to Example 1, Comparative Example 1 showed a decrease in moisture absorption rate, formaldehyde removal rate (50%RH), and formaldehyde removal rate (80%RH); Comparative Example 2 showed a decrease in moisture absorption rate, formaldehyde removal rate (50%RH), and formaldehyde removal rate (80%RH); and Comparative Example 3 showed an increase in moisture absorption rate, a decrease in formaldehyde removal rate (50%RH), and a decrease in formaldehyde removal rate (80%RH). This is because Comparative Example 1 used a co-curing method, where the high concentration of the hygroscopic agent calcium chloride could not be pre- and stably embedded in the core. The prepared particles contained almost no effective hygroscopic components, and the weak hygroscopic capacity caused a water film to quickly form on the particle surface, clogging the pores and deactivating the exposed catalyst, resulting in a decrease in formaldehyde removal efficiency. Comparative Example 2 omitted the chemical cross-linking curing step in the assembly process, and the shell maintained only by electrostatic interaction collapsed structurally during the gradient solvent replacement step. The final product may be an exposed core or broken gel sheets, with the active component MnO... X A significant amount of AC was lost, resulting in a decrease in moisture absorption and formaldehyde removal rate. Comparative Example 3, without surface hydrophobic modification, had a higher moisture absorption rate than Example 1. This is because the hydrophilic surface enhances the adsorption of water vapor, and the capillary coagulation between the clumps after particle adhesion may also lock in more moisture. However, the agglomeration phenomenon hinders air circulation, and only the particles on the surface of the clumps can come into contact with formaldehyde, leading to a decrease in formaldehyde removal rate.

[0091] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions, characterized in that, The preparation method includes: S1, Activated carbon is added to the MES buffer solution, and potassium permanganate solution is added dropwise to the MES buffer solution to react and obtain MnO. X @AC powder, the MnO X Including MnO2, MnOOH and Mn3O4; S2, sodium alginate solution is dropped into calcium chloride curing solution, and then transferred to calcium chloride solution for curing to obtain core microspheres. The core microspheres are then sequentially immersed in shell layer A solution and shell layer B solution for assembly to obtain layered microspheres. The layered microspheres are then transferred to crosslinking solution for crosslinking at room temperature in the dark, and then placed in ethanolamine solution for end-capping to obtain crosslinked microspheres. The crosslinking solution is an aqueous solution of 2-morpholinoethanesulfonic acid, 1-(3-dimethylaminopropyl)-3-ethylcarboimide and N-hydroxysuccinimide. S3, cross-linked microspheres are subjected to gradient solvent replacement, and after replacement, they are transferred to hydrolysate and then to condensation solution to obtain activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions. The preparation method of the shell layer A solution is as follows: (1-1.5) g of chitosan is dissolved in 100 g of 1 wt.% acetic acid aqueous solution, and the pH is adjusted to 4.5-5 using 0.1 mol / L acetic acid aqueous solution; The preparation method of the shell layer B solution is as follows: (2-2.5) g MnO X @AC powder is dispersed in 100g of 10mmol / L NaCl solution and sonicated for 15-20min. 1g of sodium alginate is added. The shell layer B solution is sonicated for 5min before use. The assembly procedure is as follows: the core microspheres are adsorbed in shell solution A for 15-20 minutes and then washed with deionized water. Then they are placed in shell solution B for 15-20 minutes and washed with deionized water. This step is counted as one cycle, and a total of 8 cycles are performed. The gradient solvent exchange includes the following steps: A1, a mixed solvent of anhydrous ethanol, glycerol and deionized water is used for displacement, and the displacement time is 60-65 min. The mass ratio of anhydrous ethanol, glycerol and deionized water in the mixed solvent is 25:1:

74. A2, use a 50 wt.% ethanol solution for replacement, the replacement time is 60-65 min; A3, use 75wt.% ethanol solution for replacement, the replacement time is 30-35min; A4, use 95wt.% ethanol solution for replacement, the replacement time is 30-35min; A5, use anhydrous ethanol for replacement, the replacement time is 30-35 min.

2. The method for preparing activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions according to claim 1, characterized in that, In S1: The mass ratio of activated carbon, MES buffer solution and potassium permanganate solution is (5-6):(200-210):

200.

3. The method for preparing activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions according to claim 1, characterized in that, In S2: The mass ratio of sodium alginate solution, calcium chloride curing liquid and calcium chloride solution is (100-110):1000:1000.

4. The method for preparing activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions according to claim 1, characterized in that, In S2: The crosslinking solution contains 0.1 mol / L of 2-morpholinoethanesulfonic acid, 50 mmol / L of 1-(3-dimethylaminopropyl)-3-ethylcarboimide, and 25 mmol / L of N-hydroxysuccinimide. The pH of the crosslinking solution is 6-6.

5. The solid-liquid mass ratio of the layered microspheres to the crosslinking liquid is not higher than 1:20; The solid-liquid mass ratio of the layered microspheres to the ethanolamine solution is not higher than 1:

20.

5. The method for preparing activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions according to claim 1, characterized in that, In S3: The hydrolysate is prepared by dissolving hexadecyltrimethoxysilane in a 50 wt.% aqueous ethanol solution, adjusting the pH of the aqueous ethanol solution to 4.5-5 with glacial acetic acid, and the mass ratio of hexadecyltrimethoxysilane to the ethanol solution is 5:

95.

6. The method for preparing activated carbon gel precursor particles with both dehumidification and formaldehyde removal functions according to claim 1, characterized in that, In S3: The condensation solution is a mixed solution of anhydrous ethanol and triethylamine, wherein the mass ratio of anhydrous ethanol to triethylamine is 99.8:0.2; The solid-liquid mass ratio of the cross-linked microspheres to the gradient solvent is no higher than 1:20; The solid-liquid mass ratio of the cross-linked microspheres to the hydrolysate is not higher than 1:20; The solid-liquid mass ratio of the cross-linked microspheres to the condensation liquid is not higher than 1:

20.

7. An activated carbon gel precursor particle with both dehumidification and formaldehyde removal functions obtained by the preparation method according to any one of claims 1-6.

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