CN115137669B - Preparation method of silicon dioxide loaded nano-silver composite material - Google Patents
Preparation method of silicon dioxide loaded nano-silver composite material Download PDFInfo
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K8/00—Cosmetics or similar toiletry preparations
- A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
- A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
- A61K8/25—Silicon; Compounds thereof
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K8/00—Cosmetics or similar toiletry preparations
- A61K8/02—Cosmetics or similar toiletry preparations characterised by special physical form
- A61K8/0241—Containing particulates characterized by their shape and/or structure
- A61K8/0279—Porous; Hollow
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K8/00—Cosmetics or similar toiletry preparations
- A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
- A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K8/00—Cosmetics or similar toiletry preparations
- A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
- A61K8/72—Cosmetics or similar toiletry preparations characterised by the composition containing organic macromolecular compounds
- A61K8/84—Cosmetics or similar toiletry preparations characterised by the composition containing organic macromolecular compounds obtained by reactions otherwise than those involving only carbon-carbon unsaturated bonds
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
- A61P31/00—Antiinfectives, i.e. antibiotics, antiseptics, chemotherapeutics
- A61P31/02—Local antiseptics
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
- A61Q11/00—Preparations for care of the teeth, of the oral cavity or of dentures; Dentifrices, e.g. toothpastes; Mouth rinses
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K2800/00—Properties of cosmetic compositions or active ingredients thereof or formulation aids used therein and process related aspects
- A61K2800/20—Chemical, physico-chemical or functional or structural properties of the composition as a whole
- A61K2800/28—Rubbing or scrubbing compositions; Peeling or abrasive compositions; Containing exfoliants
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K2800/00—Properties of cosmetic compositions or active ingredients thereof or formulation aids used therein and process related aspects
- A61K2800/40—Chemical, physico-chemical or functional or structural properties of particular ingredients
- A61K2800/60—Particulates further characterized by their structure or composition
- A61K2800/61—Surface treated
- A61K2800/614—By macromolecular compounds
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K2800/00—Properties of cosmetic compositions or active ingredients thereof or formulation aids used therein and process related aspects
- A61K2800/40—Chemical, physico-chemical or functional or structural properties of particular ingredients
- A61K2800/60—Particulates further characterized by their structure or composition
- A61K2800/61—Surface treated
- A61K2800/62—Coated
- A61K2800/621—Coated by inorganic compounds
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/30—Against vector-borne diseases, e.g. mosquito-borne, fly-borne, tick-borne or waterborne diseases whose impact is exacerbated by climate change
Abstract
The invention belongs to the technical field of inorganic materials, and particularly relates to a preparation method of a silicon dioxide loaded nano-silver composite material. According to the method, dopamine hydrochloride is added in the process of preparing silicon dioxide by a precipitation method, so that polydopamine is generated, has reducibility and can be reduced to generate nano silver, other reducing agents are added to improve the load rate of the nano silver, the silver content in the residual reaction solution is reduced, then the regenerated silicon dioxide is coated outside the nano silver, the polydopamine has adhesiveness, the nano silver and the outer-layer silicon dioxide can be prevented from falling off, the load rate of the nano silver is improved, and the silver residue in the reaction solution is reduced; and the obtained silicon dioxide loaded nano-silver composite material has proper friction cleaning capability.
Description
Technical Field
The invention belongs to the technical field of inorganic materials, and particularly relates to a preparation method of a silicon dioxide loaded nano-silver composite material.
Background
The incidence rate of oral diseases is high, the number of diseased groups is large, the dental diseases seriously affect daily life and even possibly cause oral cancer, so that the care of the health of teeth and the establishment of a good oral environment are very important. The selection and use of toothpaste is an important link in preventing dental diseases. The tooth disease is mainly caused by harmful flora in oral cavity, the antibacterial agent added in the toothpaste can inhibit the growth of bacteria, the common antibacterial agent triclosan can generate chloroform with chlorine in tap water, so that carcinogenicity exists, and the common antibacterial agent can influence the secretion of hormone of human body to make bacteria generate drug resistance. Fluorine in the fluorine-containing toothpaste has potential toxicity to human bodies while inhibiting and killing bacteria. The silver is used as a broad-spectrum antibacterial agent, is safe, non-toxic and non-irritant, can prevent oral diseases caused by various harmful microorganisms, and has a lasting drug effect.
The abrasive is used as an essential component in toothpaste and can help to remove tartar on the surface of teeth. Silica has chemical inertness, toothpaste system compatibility and suitable attrition values, and is well suited as an abrasive. But the porous and large inner surface area of the film is easy to absorb moisture in the air, and bacteria are easy to breed in the storage process.
The silica-loaded silver is prepared into the composite material, so that the problem of bacteria breeding during storage can be solved, and the use of a bacteriostatic agent in a toothpaste system can be omitted. At present, the silicon dioxide loaded nano silver is mainly prepared by a method of physically adsorbing nano silver on synthetic silicon dioxide, the nano silver has low loading rate, easy shedding and poor stability, the preparation method is complex, the reaction time is long, the cost is high, the silver content in the residual reaction liquid is higher, and the environmental pollution is great. Meanwhile, in the prior art, a sodium silicate solution and a silver ion solution are uniformly mixed, and then the loading of nano silver is completed in the process of separating out silicon dioxide by adopting an acid-alkali dripping mode, but the obtained material has low nano silver loading capacity, is easy to fall off, has high silver residue and can cause the reduction of the yield and the purity of the silicon dioxide. In addition, in the related technology, after a silicon dioxide product is prepared, the silicon dioxide product is subjected to drying grinding and surface modification, and then nano silver is loaded, but the method has the advantages of low treatment capacity, long surface modification time (up to 18-30 h) and high production cost.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the first aspect of the invention provides a preparation method of a silicon dioxide loaded nano-silver composite material, dopamine or salt thereof is added in the process of preparing silicon dioxide by a precipitation method, the generated poly-dopamine has reducibility and can be reduced to generate nano-silver, other reducing agents are added to improve the load rate of the nano-silver, the silver content in the residual reaction solution is reduced, then the silicon dioxide is generated to be coated outside the nano-silver, the poly-dopamine has adhesiveness, the nano-silver and the outer layer silicon dioxide can be prevented from falling off, the load rate of the nano-silver is improved, and the silver residue in the reaction solution is reduced; and the obtained silicon dioxide loaded nano silver composite material has proper friction cleaning capability.
The second aspect of the invention provides the silicon dioxide loaded nano-silver composite material obtained by the preparation method.
The third aspect of the invention is to provide the application of the silica-supported nano silver composite material.
Specifically, the invention adopts the following technical scheme:
the first aspect of the invention provides a preparation method of a silicon dioxide loaded nano-silver composite material, which comprises the following steps:
s1, adding acid into a mixed solution of sodium sulfate and sodium silicate to react to obtain a silicon dioxide inner core;
s2, reacting the silicon dioxide kernel with dopamine or salt thereof and silver ions to obtain an intermediate material which is used for modifying polydopamine and loading nano silver on the surface of the silicon dioxide kernel;
and S3, simultaneously adding sodium silicate and acid into the intermediate material for reaction to obtain the silicon dioxide loaded nano-silver composite material with the surface of the intermediate material coated with the silicon dioxide shell.
According to the preparation method, firstly, a sodium sulfate solution and a sodium silicate solution are mixed, silicon dioxide can be rapidly precipitated under the action of sodium sulfate in an acid-drop alkali mode to prepare a core with a compact structure, then dopamine or salt thereof is added, dopamine can be rapidly polymerized to generate polydopamine under the condition of high temperature, the polymerization speed of the dopamine is increased by the strong oxidizing property of silver ions, and then polydopamine and nano-silver are subjected to surface modification on the silicon dioxide core by utilizing the strong adhesion capacity of the polydopamine to silicon dioxide and the strong reducibility of the polydopamine to the silver ions. And then, continuously depositing silicon dioxide on the surface modified poly-dopamine and nano-silver loaded silicon dioxide inner core in an acid-base co-dripping mode to form a shell, wherein the core and the shell of the silicon dioxide are better wrapped and combined in the presence of poly-dopamine, the nano-silver is not easy to run off, and the silicon dioxide shell generated by acid-base co-dripping is loose and porous and has proper friction cleaning capability.
Therefore, according to the preparation method provided by the invention, the loading rate of the nano-silver can be effectively improved, the nano-silver is prevented from falling off, the composite material has a good antibacterial effect, and the obtained silicon dioxide loaded nano-silver composite material has proper friction cleaning capability.
In some embodiments of the invention, in step S1, the pH is controlled during the reaction to be in the range of 9 to 11, preferably 9.5 to 10.5, e.g. 9,9.5, 10, 10.5, 11, etc.
In some embodiments of the present invention, in step S1, the addition of the acid is stopped when the reaction reaches a pH of not less than 8.5, preferably when the pH reaches 8.5.
In some examples of the invention, in step S1, the acid comprises sulfuric acid at a concentration of 2-10M, preferably 4-6M, for example 2M,3M,4M,5M,6M,7M,8M,9M,10M, etc.
In some embodiments of the invention, the acid is added at a rate of 3 to 10m in step S1 3 H, preferably from 4.5 to 7.5m 3 H, e.g. 3m 3 /h，3.5m 3 /h，4m 3 /h，4.5m 3 /h，5m 3 /h，5.5m 3 /h，6m 3 /h，6.5m 3 /h，7m 3 /h，7.5m 3 /h，8m 3 /h，8.5m 3 /h，9m 3 /h，9.5m 3 /h，10m 3 H, etc.
In some embodiments of the invention, the temperature of the reaction in step S1 is 50 to 99 ℃, preferably 60 to 90 ℃, more preferably 65 to 85 ℃, such as 50 ℃,55 ℃,60 ℃,65 ℃,70 ℃,75 ℃,80 ℃,85 ℃,90 ℃,95 ℃,99 ℃ and the like.
In some embodiments of the present invention, in the mixed solution of sodium sulfate and sodium silicate, the ratio of sodium sulfate to sodium silicate is 4-40g:1mol, for example 4g:1mol,6g:1mol,8g:1mol,10g:1mol,12g:1mol,14g:1mol, 1lg: 1mol,18g:1mol,20g:1mol,22g:1mol,24g:1mol,26g:1mol,28g:1mol,30g:1mol,32g:1mol,34g:1mol,36g:1mol,38g:1mol,40g:1mol, etc.
In some examples of the present invention, the mixed solution of sodium sulfate and sodium silicate has a mass concentration of sodium sulfate of 0.1% to 2.5%, such as 0.1%,0.2%,0.3%,0.4%,0.5%,0.6%,0.7%,0.8%,0.9%,1%,1.2%,1.4%,1.6%,1.8%,2%,2.2%,2.4%,2.5%, etc.; the concentration of sodium silicate is 0.5 to 1.5M, for example, 0.5M,0.6M,0.7M,0.8M,0.9M,1M,1.1M,1.2M,1.3M,1.4M,1.5M, etc.
In some examples of the present invention, the mixed solution of sodium sulfate and sodium silicate may be obtained by mixing a sodium sulfate solution with a sodium silicate solution, considering the difference in solubility of sodium sulfate and sodium silicate. The sodium sulfate solution has a mass concentration of 0.5% to 5%, preferably 1% to 3%, for example 0.5%,1%,1.5%,2%,2.5%,3%,3.5%,4%,4.5%,5%, etc. The sodium silicate solution has a concentration of 1 to 5M, preferably 2 to 3M, for example, 1M,1.5M,2M,2.5M,3M,3.5M,4M,4.5M,5M, etc. The sodium silicate solution can be prepared by liquefying solid sodium silicate at high temperature and adding water, wherein the modulus of the solid sodium silicate is 2-4, preferably 3-3.5. The volume ratio of the sodium sulfate solution to the sodium silicate solution is preferably 1-5:1, preferably 1.4 to 2.4:1, e.g. 1:1,1.2:1,1.4:1,1.6:1,1.8:1,2:1,2.2:1,2.4:1,2.6:1,2.8:1,3:1,3.2:1,3.4:1,3.6:1,3.8:1,4:1,4.2:1,4.4:1,4.6:1,4.8:1,5:1, etc.
In some embodiments of the invention, the ratio of dopamine or salt thereof in step S2 to sodium silicate in step S1 is 0.5-3g:1mol, preferably 0.7 to 2g:1mol, for example 0.5g:1mol,0.7g:1mol,1g: 1.2g, 1 mol: 1mol,1.4g:1mol,1.6g:1mol,1.8g:1mol,2g:1mol,2.2g:1mol,2.4g:1mol,2.6g:1mol,2.8g:1mol,3g:1mol, and the like.
In some embodiments of the invention, the molar ratio of silver ions in step S2 to sodium silicate in step S1 is from 0.05 to 1:1, preferably 0.09 to 0.6:1, e.g. 0.05:1,0.05:1,0.09:1,0.1:1,0.12:1,0.14:1,0.16:1,0.18:1,0.2:1,0.25:1,0.3:1,0.35:1,0.4:1,0.45:1,0.5:1,0.55:1,0.6:1,0.65:1,0.7:1,0.75:1,0.8:1,0.85:1,0.9:1,0.95:1,1:1. preferably, the silver ions are reacted with the silica core in the form of a silver ion solution having a concentration of 0.5 to 5M, preferably 1 to 2M, such as 0.5M,1M,1.5M,2M,2.5M,3M,3.5M,4M,4.5M,5M, and the like. In practical operation, the mixed solution containing the silicon dioxide inner core is obtained in the step S1, and the silver ion solution is 2-5m 3 H, preferably from 2.5 to 3.5m 3 The reaction mixture was added at a rate of/h. Preferably, the silver ion solution comprises a silver nitrate solution.
In some embodiments of the present invention, during or after the reaction between the silica core and dopamine or its salt and silver ions, a step of reducing the silver ions by adding a reducing agent is further included. Preferably, the reducing agent comprises at least one of sodium citrate, vitamin C, ascorbic acid, sodium ascorbate, preferably sodium citrate. By adding the reducing agent, silver ions in the solution can be fully reduced into nano silver, the silver content in the residual reaction liquid is reduced, the nano silver loading rate is improved, and the guarantee is provided for green production.
In some examples of the invention, the mass ratio of the reducing agent to dopamine or salt thereof is 1:1.5-8, preferably 1:1.8-6.7, e.g. 1:1.5,1:1.8,1:2,1:2.2,1:2.4,1:2.6,1:2.8,1:3,1:3.5,1:4,1:4.5,1:5,1:5.5,1:6,1:6.5,1:6.7,1:7,1:7.5,1:8, and the like. Preferably, the dopamine salt comprises dopamine hydrochloride.
In some examples of the present invention, the reaction in steps S1 and S2 is carried out under stirring at a rate of 10 to 50Hz, preferably 20 to 40Hz, such as 10Hz,15Hz,20Hz,25Hz,30Hz,33Hz,35Hz,40Hz,45Hz,50Hz, etc., independently.
In some examples of the present invention, in step S3, the pH of the system is controlled to 8 to 9 during the reaction, and the addition of the acid is stopped until the pH reaches 4 to 5. In step S3, the acid comprises sulfuric acid at a concentration of 2-10M, preferably 4-6M, for example, 2M,3M,4M,5M,6M,7M,8M,9M,10M, etc. The sulfur isThe concentration of the acid may be the same as the concentration of sulfuric acid in step S1, or may be different from the concentration of sulfuric acid in step S1. The addition speed of the sulfuric acid is 3-10m 3 H, preferably from 4.5 to 7.5m 3 H, e.g. 3m 3 /h，3.5m 3 /h，4m 3 /h，4.5m 3 /h，5m 3 /h，5.5m 3 /h，6m 3 /h，6.5m 3 /h，7m 3 /h，7.5m 3 /h，8m 3 /h，8.5m 3 /h，9m 3 /h，9.5m 3 /h，10m 3 H, etc.
In some examples of the invention, the molar ratio (or mass ratio) of the sodium silicate in step S3 to the sodium silicate in step S1 is 1:0.5 to 5, preferably 1:1-2.3, e.g. 1:0.5,1:1,1:1.5,1:2,1:2.3,1:2.5,1:3,1:3.5,1:4,1:4.5,1:5, and the like. Preferably, the sodium silicate in step S3 is added in the form of a solution to the mixed solution containing the intermediate material obtained in step S2, the concentration of the sodium silicate solution is 1 to 5M, preferably 2 to 3M, for example, 1m,1.5m,2m,2.5m,3m,3.5m,4m,4.5m,5m, etc., and the concentration of the sodium silicate solution in step S3 may be the same as or different from that in step S1. The adding speed of the sodium silicate solution is 5-20m 3 H, preferably from 10 to 14m 3 H, e.g. 5m 3 /h，6m 3 /h，7m 3 /h，8m 3 /h，9m 3 /h，10m 3 /h，11m 3 /h，12m 3 /h，13m 3 /h，14m 3 /h，15m 3 /h，16m 3 /h，17m 3 /h，18m 3 /h，19m 3 /h，20m 3 H, etc.
In some examples of the invention, in step S3, the reaction is kept under stirring at a rate of 10 to 50Hz, preferably 20 to 40Hz, for example, 10Hz,15Hz,20Hz,25Hz,30Hz,33Hz,35Hz,40Hz,45Hz,50Hz, etc. The stirring speed in step S3 may be the same as that in step S1 or S2, or may be different. Preferably, in step S3, after the addition of sulfuric acid is stopped, the stirring speed may be reduced, and the stirring may be continued to complete the reaction.
In some examples of the present invention, step S3 further includes a post-treatment process after the reaction is completed. The post-treatment may be carried out by filtration, washing, drying and the like, which are techniques commonly used in the art.
In some embodiments of the present invention, after steps S1 and S2 are completed, post-processing is not required, and the next step can be performed directly.
In some embodiments of the present invention, the solution involved in the preparation method of the present invention is an aqueous solution, a small molecule alcohol (e.g. methanol, ethanol) solution, or a small molecule alcohol-aqueous solution, preferably an aqueous solution.
In some more preferred embodiments of the present invention, the method for preparing the silica-supported nano-silver composite material comprises the steps of:
step one, preparing a sodium sulfate solution: dissolving sodium sulfate in water to obtain 1.0-3.0% solution;
step two, preparing a sodium silicate solution: liquefying solid sodium silicate with modulus of 3.0-3.5 at high temperature, adding water to prepare 2.0-3.0M solution;
step three, preparing a sulfuric acid solution: preparing 4.0-6.0M sulfuric acid solution;
fourthly, dissolving silver nitrate in water to prepare a solution with the concentration of 1.0-2.0M;
fifthly, adding the sodium sulfate solution of 10-12m in the first step into a reaction tank 3 Sodium silicate solution 5-7m 3 Heating to 65-85 deg.C, stirring at 10-50Hz and 4.5-7.5m 3 Dropwise adding a sulfuric acid solution at a flow rate of/h, controlling the pH value of the reaction process to be 9.5-10.5, and stopping adding acid when the pH value of the solution reaches 8.5;
sixthly, continuously adding 15-20kg of dopamine or salt thereof into the reaction kettle by 2.5-3.5m 3 Dropping at a flow rate of 2-3m 3 Adding 3-8kg of sodium citrate into the silver nitrate solution after the dropwise addition of the silver nitrate solution is finished, and stirring for 1-3h;
seventhly, continuing to move to the reaction tank by 10-14m 3 Dripping 3-5m of sodium silicate solution at the flow rate of/h 3 At 4.5-7.5m 3 Dropwise adding a sulfuric acid solution at a flow rate of/h, controlling the pH value of the reaction process to be 8.0-9.0, and stopping adding acid at a stirring speed of 5-20Hz for 0.5-2h when the pH value of the solution reaches 4.0-5.0;
and eighthly, carrying out filter pressing, washing and drying on the materials to obtain the silicon dioxide loaded nano silver composite material.
The second aspect of the invention provides the silica-supported nano silver composite material obtained by the preparation method.
In some examples of the invention, the silica-supported nanosilver composite has any one or more of the following technical parameters: (1) the water absorption capacity is 15-20mL/20g; (2) oil absorption value of 100-150mL/100g; (3) the copper loss value is 5.0-7.0mg; (4) The bacteriostasis rate to any one or more of colibacillus, staphylococcus aureus, pseudomonas aeruginosa and aspergillus niger is more than 99 percent.
The third aspect of the invention provides application of the silicon dioxide loaded nano-silver composite material in preparing an abrasive, a bacteriostatic agent or toothpaste.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a novel preparation method of a silicon dioxide composite material for loading and preventing nano silver from falling off, dopamine hydrochloride is added in the process of preparing silicon dioxide by a precipitation method to generate poly-dopamine which has reducibility and can be reduced to generate nano silver, sodium citrate or other reducing agents are added to further improve the loading rate of the nano silver, the silver content in the residual reaction liquid is reduced, then the silicon dioxide is generated to be coated outside the nano silver, and the poly-dopamine which has adhesiveness can prevent the nano silver and the outer layer silicon dioxide from falling off.
Meanwhile, the silver ion solution is added after the silicon dioxide core is formed, so that the influence on the precipitation of the silicon dioxide is small, and the yield and the purity of the silicon dioxide are improved. Compared with the prior art of carrying out post-treatment on a silicon dioxide product and then carrying out nano silver loading, the method has the advantages of short modification time, preparation in a reaction process, simple preparation method, high yield and cost reduction.
In addition, the invention controls the precipitation condition of the silicon dioxide, so that the inner core of the silicon dioxide is a compact structure, and the outer shell of the silicon dioxide on the outer surface is loose and porous, has proper friction cleaning capability, and can be applied to toothpaste as an abrasive and a bacteriostatic agent.
In short, the preparation process of the silica-loaded nano silver is simple, the conditions can be controlled, the adsorption efficiency of the nano silver is improved, the content of residual silver in a reaction solution can be reduced, meanwhile, the nano silver loading rate of the silica is high, the antibacterial rate of the silica on escherichia coli, staphylococcus aureus, pseudomonas aeruginosa and aspergillus niger is more than 99%, the nano silver is not easy to fall off, the silica composite material has the functions of antibiosis and cleaning friction, and the formula of the toothpaste can be simplified.
Detailed Description
The technical solution of the present invention is further described below with reference to specific examples. The starting materials used in the following examples, unless otherwise specified, are available from conventional commercial sources; the processes used, unless otherwise specified, are conventional in the art.
Example 1
The embodiment provides a preparation method of a silica-supported nano-silver composite material, which comprises the following steps:
firstly, dissolving sodium sulfate in water to prepare a solution with the mass concentration of 1.0%, and stirring for 30 minutes for later use.
And step two, liquefying solid sodium silicate with the modulus of 3.0 at high temperature, adding water to prepare a solution with the concentration of 2.0M, and stirring for 30 minutes for later use.
Thirdly, preparing 4.0M sulfuric acid solution and stirring for 30 minutes for later use.
And fourthly, dissolving silver nitrate in water to prepare a solution with the concentration of 1.2M, and stirring for 30 minutes for later use.
Step five, adding the sodium sulfate solution 10m prepared in the step one into a reaction tank 3 7m of sodium silicate solution prepared in the second step 3 Heating to 65 deg.C, stirring at 33Hz and 4.0m 3 Dropwise adding the sulfuric acid solution prepared in the step S3 at the flow rate of/h, controlling the pH value in the reaction process to be 9.5-10.5, and stopping adding acid when the pH value of the solution reaches 8.5.
Sixthly, continuously adding 15kg of dopamine hydrochloride into the reaction kettle,at 2.5m 3 Dripping silver nitrate solution with the flow rate of 2.5 m/h 3 After the silver nitrate solution is dripped, 3kg of sodium citrate is added, and the mixture is stirred for 2 hours.
Seventh step, continue to 10m to the reaction tank 3 Dropping sodium silicate solution 5m at a flow rate of/h 3 At 5.0m 3 Dropwise adding sulfuric acid solution at a flow rate of/h, controlling the pH value of the solution to be 8.0-9.0 in the reaction process, stopping adding acid when the pH value of the solution reaches 4.0-5.0, and stirring for 1h at a stirring speed of 15 Hz.
And eighthly, carrying out filter pressing, washing and drying on the material prepared in the seventh step to obtain the silicon dioxide loaded nano silver composite material.
Example 2
The embodiment provides a preparation method of a silicon dioxide-loaded nano silver composite material, which comprises the following steps:
first, sodium sulfate was dissolved in water to prepare a 2.0% solution, and the solution was stirred for 30 minutes.
And step two, after the solid sodium silicate with the modulus of 3.2 is liquefied at high temperature, adding water to prepare a solution with the concentration of 2.5M, and stirring for 30 minutes for later use.
Thirdly, preparing 5.0M sulfuric acid solution and stirring for 30 minutes for later use.
And fourthly, dissolving silver nitrate in water to prepare a solution with the concentration of 1.8M, and stirring for 30 minutes for later use.
Step five, adding 11m of the sodium sulfate solution prepared in the step one into a reaction tank 3 6m of sodium silicate solution prepared in the second step 3 Heating to 75 deg.C, stirring at 33Hz and 5.0m 3 Dropwise adding the sulfuric acid solution prepared in the step S3 at the flow rate of/h, controlling the pH value in the reaction process to be 9.5-10.5, and stopping adding acid when the pH value of the solution reaches 8.5.
Sixthly, continuously adding 15kg of dopamine hydrochloride into the reaction kettle by 3.0m 3 Dripping silver nitrate solution 2m at the flow rate of/h 3 After the dropwise addition of the silver nitrate solution is finished, 5kg of sodium citrate is added, and the mixture is stirred for 2 hours.
Seventh, continue to 12m to the reaction tank 3 Dropping sodium silicate solution 4m at a flow rate of/h 3 At 6.0m 3 Dripping sulfuric acid solution at the flow rate of/h, and controlling the reactionThe pH value of the process is 8.0-9.0, and the acid addition is stopped at a stirring speed of 15Hz for 1h when the pH value of the solution reaches 4.0-5.0.
And eighthly, carrying out filter pressing, washing and drying on the material prepared in the seventh step to obtain the silicon dioxide loaded nano silver composite material.
Example 3
The embodiment provides a preparation method of a silica-supported nano-silver composite material, which comprises the following steps:
first, sodium sulfate was dissolved in water to prepare a 3.0% solution, and the solution was stirred for 30 minutes.
And step two, after the solid sodium silicate with the modulus of 3.5 is liquefied at high temperature, adding water to prepare a solution with the concentration of 3.0M, and stirring for 30 minutes for later use.
Thirdly, preparing 6.0M sulfuric acid solution and stirring for 30 minutes for later use.
Fourthly, dissolving silver nitrate in water to prepare a solution with the concentration of 2.0M, and stirring for 30 minutes for later use.
Step five, adding the sodium sulfate solution 12m prepared in the step one into a reaction tank 3 Sodium silicate solution 5m prepared in the second step 3 Heating to 85 deg.C, stirring at 33Hz and 6.0m 3 Dropwise adding the sulfuric acid solution prepared in the step S3 at the flow rate of/h, controlling the pH value in the reaction process to be 9.5-10.5, and stopping adding acid when the pH value of the solution reaches 8.5.
Sixthly, continuously adding 15kg of dopamine hydrochloride into the reaction kettle by 3.5m 3 Dropping silver nitrate solution at a flow rate of 2 m/h 3 After the silver nitrate solution is dripped, 8kg of sodium citrate is added, and the mixture is stirred for 2 hours.
Seventh step, continue to 10m to the reaction tank 3 Dropping sodium silicate solution at the flow rate of 3m 3 At 7.0m 3 Dropwise adding sulfuric acid solution at a flow rate of/h, controlling the pH value of the solution to be 8.0-9.0 in the reaction process, and stopping adding acid at a stirring speed of 15Hz for 1h when the pH value of the solution reaches 4.0-5.0.
And eighthly, carrying out filter pressing, washing and drying on the material prepared in the seventh step to obtain the silicon dioxide silver-loaded composite material.
Comparative example 1
Preparation of this comparative exampleThe preparation process is similar to that of example 2, except that 3.5m after the fifth step of adding sodium silicate solution 3 Dropping silver nitrate solution at a flow rate of 2 m/h 3 And after the fifth step reaction is finished, implementing the seventh step without adding dopamine and sodium citrate.
Comparative example 2
This comparative example was prepared similarly to example 2 except that 3.5m was used after the sodium silicate solution was added in the fifth step 3 Dropping silver nitrate solution at a flow rate of 2 m/h 3 And sixthly, adding no silver nitrate solution.
Comparative example 3
The comparative example was prepared similarly to example 2, except that dopamine hydrochloride was not added in the sixth step, as in example 2.
Comparative example 4
The comparative example was prepared similarly to example 2, except that sodium citrate was not added in the sixth step, as in example 2.
Comparative example 5
The comparative example was prepared in a similar manner to example 2 except that, after the sodium sulfate solution was added in the fifth step, the sodium silicate solution and the sulfuric acid solution were simultaneously dropped into the reaction tank at a dropping speed of 12m 3 H, the total addition amount of the sodium silicate solution and the sulfuric acid solution is 12m 3 。
Comparative example 6
The comparative example was prepared similarly to example 2, except that in the fifth step, an equal amount of water was used instead of the sodium sulfate solution.
Comparative example 7
The comparative example was prepared in a manner similar to that of example 2.
The difference between the comparative example and the example 2 is that the seventh step is directly carried out after the fifth step reaction, the material obtained in the seventh step is subjected to pressure filtration, washing and drying to obtain silicon dioxide, then 2g of the silicon dioxide is added into 400mL of Tris-HCl buffer solution (pH = 8.5) containing 15mg of dopamine hydrochloride, the mixture is stirred at 200rpm for 2h at room temperature for dopamine modification, and after washing and drying, the mixture is added into 200mL0.1M silver nitrate solution, stirred at 200rpm for 2h at room temperature (20 ℃) and then dried after washing.
Comparative example 8
The preparation method is similar to the embodiment 2.
The difference between the comparative example and the example 2 is that the seventh step is directly implemented after the fifth step reaction, the material obtained in the seventh step is subjected to filter pressing, washing and drying to obtain silicon dioxide, then 2g of the silicon dioxide is added into 400mL of Tris-HCl buffer solution (pH = 8.5) containing 15mg of dopamine hydrochloride, the mixture is stirred at the stirring speed of 200rpm at 75 ℃ for 2h for dopamine modification, and after washing and drying, the mixture is added into 200mL0.1M silver nitrate solution, stirred at the stirring speed of 200rpm at 75 ℃ for 2h, and after washing and drying, the mixture is dried.
Performance testing
Test samples: the silica-supported nano silver composite materials prepared in examples 1 to 3 and comparative examples 1 to 8;
the test method comprises the following steps:
and (3) determining the water absorption capacity, the oil absorption value and the copper consumption: reference is made to QB/T2346-2015;
residual silver content (residual silver content) of the reaction solution: the ICP method uses an AG-1 silver ion analyzer, shanghai war electron technology, inc.
The silver content of the composite material is as follows: concentrated nitric acid digestion, ICP method, using AG-1 silver ion tester, shanghai war electron technology, inc.
The antibacterial property: standard strains (supplied by Kyork microbiology Co., ltd., guangdong) were used: escherichia coli ATCC25922, pseudomonas aeruginosa ATCC27853, staphylococcus aureus ATCC25923, aspergillus niger ATCC16404.
(1) Quantitative test for bacteriostatic performance (no immersion): quantitatively measuring the sterilization performance by using a plate counting method, putting 1g of sample into the bacterial suspension containing the strain, uniformly oscillating, taking 1mL of bacterial liquid, and diluting in a test tube containing sterile water to obtain the bacterial liquid before bacteriostasis. And (3) taking 1mL of bacterial liquid from the bacterial suspension subjected to oscillation sterilization for 24 hours, and diluting the bacterial liquid in a test tube filled with sterile water to obtain the bacterial liquid subjected to bacterial inhibition. And respectively taking 1mL of the two treated bacterial liquids, transferring the two bacterial liquids into a culture dish, injecting culture solution at about 45 ℃, culturing at 37 ℃ for 24 hours at constant temperature, taking out the plate, counting, repeating the test for 3 times, and averaging the values.
(2) Testing the stability of antibacterial performance (after dipping): and (3) putting 10g of sample into 400mL of deionized water, soaking for 48h, stirring for 15min every 12h, filtering out the sample, adding 400mL of deionized water, soaking for 24h, taking out the sample, drying, carrying out quantitative inspection according to the step (1), and evaluating the antibacterial stability and durability of the sample.
And (3) test results:
TABLE 1 Performance test results
TABLE 2 results of the measurement of bacteriostatic properties
From the above tables 1 and 2, it can be seen that:
(1) The water absorption capacity of the silica-loaded nano-silver composite material of the embodiments 1 to 3 is 15 to 20mL/20g, the oil absorption value is 100 to 150mL/100g, the copper consumption value is 5.0 to 7.0mg, the standard requirements of the silica abradant are met, the silver content in the composite material is high, the silver content in the reaction residual liquid is lower than 5mg/L, the bacteriostasis rate to escherichia coli, pseudomonas aeruginosa, staphylococcus aureus and aspergillus niger is more than 99.9%, the bacteriostasis effect is durable, the bacteriostasis rate is still more than 99.9% after the impregnation, and the silica-loaded nano-silver is shown to be slowly released in the reaction process.
(2) Compared with the example 2, the comparative example 1 is that silver nitrate is added before the reaction starts, dopamine hydrochloride and sodium citrate are not added in the process, silver in the silver nitrate is not reduced and is adsorbed in silicon dioxide in the form of silver ions, the silver content is low, the residual silver content of the reaction liquid is high, and the bacteriostatic effect is unstable; comparative example 2 silver nitrate is added before the reaction starts, silver ions are reduced into nano silver through polydopamine and sodium citrate, the dopamine is beneficial to improving the silver content, but the precipitation of silicon dioxide in the reaction process is influenced, the silver ions are adsorbed into the silicon dioxide in advance, the storage process is unstable, and the bacteriostatic effect is reduced; comparative example 3 dopamine hydrochloride was not added, the silica and silver particles lacked adhesion, silver nitrate was reduced only by sodium citrate, the silver content in the composite material was reduced, and the residual silver content in the reaction solution was high; comparative example 4 sodium citrate was not added, the polydopamine failed to completely reduce silver nitrate, and the residual silver content in the reaction solution increased; comparative example 5 acid and alkali are used for replacing acid and alkali drop in the first step, and water is used for replacing sodium sulfate in comparative example 6, so that the copper consumption value of the silicon dioxide is reduced; comparative example 7 by treating silica with dopamine at room temperature, the result is that the bacteriostatic property before impregnation is reduced and the property after impregnation is obviously reduced; comparative example 8 by treating silica with dopamine at 75 ℃, the bacteriostatic performance before impregnation was still below 99% and the bacteriostatic effect was not durable.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (7)
1. A preparation method of a silicon dioxide loaded nano-silver composite material is characterized by comprising the following steps: the method comprises the following steps:
s1, adding acid into a mixed solution of sodium sulfate and sodium silicate to react to obtain a silicon dioxide inner core;
s2, reacting the silicon dioxide kernel with dopamine or salt thereof and silver ions to obtain an intermediate material which is used for modifying polydopamine and loading nano silver on the surface of the silicon dioxide kernel;
s3, simultaneously adding sodium silicate and acid into the intermediate material for reaction to obtain a silicon dioxide loaded nano-silver composite material with a silicon dioxide shell wrapped on the surface of the intermediate material;
the ratio of the dopamine or salt thereof in the step S2 to the sodium silicate in the step S1 is 0.5-3g:1mol;
the molar ratio of the silver ions in the step S2 to the sodium silicate in the step S1 is 0.05-1:1;
the method comprises the following steps that during or after reaction of the silicon dioxide inner core, dopamine or salt thereof and silver ions, a reducing agent is added to reduce the silver ions;
the reducing agent comprises at least one of sodium citrate, vitamin C, ascorbic acid and sodium ascorbate.
2. The method of claim 1, wherein: in the step S1, the pH is controlled to be 9-11 in the reaction process.
3. The method of claim 2, wherein: in step S1, the reaction is carried out until the pH value is not less than 8.5, and the addition of acid is stopped.
4. The method of claim 1, wherein: in step S1, the reaction temperature is 50-99 ℃.
5. The method of claim 1, wherein: in the mixed solution of sodium sulfate and sodium silicate, the ratio of sodium sulfate to sodium silicate is 4-40g:1mol.
6. The silica-supported nano-silver composite material obtained by the production method according to any one of claims 1 to 5.
7. Use of the silica-loaded nanosilver composite material of claim 6 in the preparation of an abrasive, a bacteriostatic or a toothpaste.
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