Antibacterial activated carbon-silver ion composite photocatalyst and preparation method thereof

Abstract

This invention belongs to the field of composite material preparation technology, and provides an antibacterial activated carbon-silver ion composite photocatalyst and its preparation method. First, a nitrogen-doped titanium dioxide composite carbon dot core material is prepared using a hydrothermal method and high-temperature calcination, with titanium source, nitrogen source, and self-made carbon dots as raw materials. The core material is then surface-modified using a mercaptosilane coupling agent, and nano-silver is loaded in situ onto its surface via chemical reduction to obtain a multifunctional nanopowder. Simultaneously, activated carbon undergoes surface oxidation and amination treatment, and is grafted with the active ester polyethylene glycol maleimide, thereby constructing specific reaction sites on the activated carbon surface. Finally, the multifunctional nanopowder is covalently bonded to the activated carbon carrier surface using the Michael addition reaction between maleimide and mercapto groups. The resulting composite powder is then mixed with a dispersion medium and functional additives to obtain the antibacterial activated carbon-silver ion composite photocatalyst.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation technology, and relates to an antibacterial activated carbon-silver ion composite photocatalyst and its preparation method. Background Technology

[0002] In the field of indoor environmental purification and antibacterial materials, combining activated carbon with excellent physical adsorption properties with photocatalysts and antibacterial agents that can decompose organic pollutants and kill microorganisms is a common approach to constructing multifunctional composite materials. In existing technologies, the preparation of such composite materials often employs simple physical blending or one-step impregnation and calcination methods in situ. However, these traditional methods have insurmountable drawbacks.

[0003] On the one hand, in-situ synthesis often leads to the deposition and growth of photocatalyst precursors within the microporous structure of activated carbon, severely blocking its inherent adsorption channels and weakening its core function as a highly efficient physical adsorbent. On the other hand, the binding force formed through physical adsorption or simple impregnation is usually weak. In practical use, such as under water scouring or airflow purging, functional components are easily detached from the activated carbon support, leading not only to rapid degradation of material performance and shortened lifespan, but also to secondary pollution caused by the detached nanoparticles. Furthermore, traditional photocatalysts are mostly wide-bandgap semiconductors, whose photocatalytic activity mainly depends on ultraviolet light, limiting their effectiveness in indoor environments dominated by visible light. Simultaneously, antibacterial metal components are prone to aggregation during the composite process, reducing their effective specific surface area and antibacterial efficiency. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide an antibacterial activated carbon-silver ion composite photocatalyst and its preparation method. First, functional nanoparticles with thiol groups modified on their surface are prepared. Simultaneously, maleimide groups are grafted onto the activated carbon carrier. Finally, through the reaction of thiol groups and maleimide groups, the nanoparticles are covalently anchored to the surface of the activated carbon, thereby 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 an antibacterial activated carbon-silver ion composite photocatalyst, the preparation method comprising:

[0007] S1, citric acid and urea are dispersed in deionized water and reacted to obtain carbon dots. Tetraisopropyl titanate is dissolved in anhydrous ethanol, and urea solution, carbon dots and glacial acetic acid are added to react to obtain N-TiO2@CDs precursor. Under nitrogen atmosphere, N-TiO2@CDs precursor is calcined to obtain N-TiO2@CDs.

[0008] S2, N-TiO2@CDs are dispersed in anhydrous toluene, 3-mercaptopropyltrimethoxysilane is added and reacted with glacial acetic acid to obtain N-TiO2@CDs-SH, which is then dispersed in ethylene glycol. PVP K30 is added and reacted with silver nitrate to obtain Ag@(N-TiO2@CDs-SH) powder;

[0009] S3, add activated carbon to nitric acid and stir to obtain oxidized activated carbon. Disperse the oxidized activated carbon in an ethanol aqueous solution, add 3-aminopropyltriethoxysilane and react with deionized water to obtain aminated activated carbon. Disperse the aminated activated carbon in a carbonate buffer solution, add active ester polyethylene glycol maleimide to obtain maleimide-activated carbon.

[0010] S4. Ag@(N-TiO2@CDs-SH) powder was dispersed in phosphate buffer, and maleimide-activated carbon was added to react and an antibacterial activated carbon-silver ion composite photocatalyst was obtained.

[0011] Specifically, it includes:

[0012] S1, citric acid and urea were dispersed in deionized water and then transferred to a hydrothermal reactor. The reaction was carried out hydrothermally at a first temperature. After cooling, centrifugation, dialyzing, and freeze-drying, carbon dots were obtained. Tetraisopropyl titanate was dissolved in anhydrous ethanol. Under ice bath conditions, urea solution, carbon dots, and glacial acetic acid were added. The reaction was carried out hydrothermally at a second temperature. After centrifugation, washing, and drying, N-TiO2@CDs precursor was obtained. Under a nitrogen atmosphere, N-TiO2@CDs precursor was calcined at a third temperature to obtain N-TiO2@CDs.

[0013] S2, N-TiO2@CDs were dispersed in anhydrous toluene, 3-mercaptopropyltrimethoxysilane and glacial acetic acid were added, and the reaction was carried out under nitrogen protection at the fourth temperature. After cooling, washing and drying, N-TiO2@CDs-SH was obtained and dispersed in ethylene glycol. PVP K30 and silver nitrate were added, and the reaction was carried out under nitrogen protection at the fifth temperature. The mixture was quenched in an ice-water bath, washed until the supernatant was free of silver ions, and dried to obtain Ag@ powder.

[0014] S3, add activated carbon to nitric acid, stir at the sixth temperature, pour out, wash with deionized water until the pH of the washing solution is 6-7, dry to obtain oxidized activated carbon, disperse the oxidized activated carbon in an ethanol aqueous solution, add 3-aminopropyltriethoxysilane and deionized water, pre-hydrolyze in an ice bath, react at the seventh temperature under a nitrogen atmosphere, filter, wash, dry, and then cure by moist heat to obtain aminated activated carbon, disperse the aminated activated carbon in a carbonate buffer solution, add active ester polyethylene glycol maleimide, react at room temperature, filter, wash, and dry to obtain maleimide-activated carbon;

[0015] S4. Ag@(N-TiO2@CDs-SH) powder was dispersed in phosphate buffer, maleimide-activated carbon was added, and the reaction was carried out under nitrogen protection and in the dark at room temperature. After filtration, washing and drying, an antibacterial activated carbon-silver ion composite photocatalyst was obtained.

[0016] In step S1, citric acid serves as the carbon source, and urea as the nitrogen source and passivating agent. Under hydrothermal conditions, the core of carbon nanoparticles is formed. Simultaneously, urea decomposes under high temperature and pressure, generating nitrogen-containing groups that dop into the hybrid network of the carbon core and partially passivate the carbon dot surface in the form of amino groups. The subsequent dialysis process removes unreacted small molecule precursors and byproducts. Tetraisopropyl titanate serves as the titanium source, and its hydrolysis rate is suppressed under ice bath conditions. The addition of urea aqueous solution provides the water required for hydrolysis, while urea itself acts as a nitrogen source in the subsequent hydrothermal process. Glacial acetic acid acts as both a catalyst and inhibitor, coordinating with titanium alkoxide to form a more stable precursor. The self-made carbon dots, due to their surface carboxyl and hydroxyl functional groups, can combine with the forming titanium dioxide network precursor through hydrogen bonding or alcoholysis. In the hydrothermal reaction, the titanium alkoxide precursor undergoes hydrolysis and condensation to form an amorphous titanium dioxide hydrate network, encapsulating the carbon dots and urea within it. Under subsequent calcination in a nitrogen atmosphere, the amorphous titanium dioxide undergoes a crystal transformation to generate anatase phase with photocatalytic activity. At the same time, the coated urea decomposes upon heating to produce nitrogen-containing species such as ammonia, which diffuse and replace some oxygen atoms in the titanium dioxide lattice under an oxygen-deficient environment, forming titanium-nitrogen bonds and oxygen vacancies, reducing the band gap width, and obtaining the target product N-TiO2@CDs.

[0017] In step S2, the added 3-mercaptopropyltrimethoxysilane undergoes hydrolysis of its methoxysilane under the catalysis of water and glacial acetic acid. The resulting active silanol groups react with the hydroxyl groups on the surface of the composite material via dehydration condensation, forming stable silicon-oxygen-titanium covalent bonds. This grafts the propyl segment containing the terminal thiol group onto the material surface, followed by the loading of silver nanoparticles. In ethylene glycol solvent, ethylene glycol acts as a polyol reducing agent, reducing silver ions in silver nitrate to elemental silver. The thiol functional groups on the material surface have a strong affinity for silver, forming sulfur-silver bonds, which serve as preferential nucleation sites for silver nanoparticles. This ensures that the silver particles are firmly anchored on the material surface, yielding Ag@(N-TiO2@CDs-SH) powder.

[0018] In step S3, activated carbon is oxidized with dilute nitric acid, which not only increases its hydrophilicity but also provides active sites for subsequent grafting reactions. Then, an amination treatment is performed. In an aqueous ethanol solution, the ethoxy group of 3-aminopropyltriethoxysilane hydrolyzes to a silanol group, which then undergoes a condensation reaction with the hydroxyl or carboxyl groups on the surface of the oxidized activated carbon, covalently grafting the propyl segment containing the terminal primary amino group onto the activated carbon surface. The hydrothermal curing step utilizes moisture and temperature to further crosslink the incompletely hydrolyzed silane groups, forming a denser and more stable siloxane network layer. Finally, the amination activated carbon is reacted with the activated ester polyethylene glycol maleimide in a carbonate buffer solution. This buffer provides a weakly alkaline environment, placing the primary amino groups on the activated carbon surface in a deprotonated nucleophilic state. The amino group, acting as a nucleophile, attacks the carbonyl carbon of the active ester, undergoing a nucleophilic acyl substitution reaction to form a stable amide bond. Simultaneously, the N-hydroxysuccinimide, acting as a leaving group, is released, attaching a flexible polyethylene glycol segment containing a terminal maleimide functional group to the activated carbon surface, resulting in maleimide-activated carbon. In step S4, the thiol groups on the surface of the functional powder act as nucleophiles, undergoing a Michael addition reaction with the maleimide double bonds on the activated carbon surface to form thioether bonds, firmly anchoring the functional nanoparticles to the activated carbon support via the flexible polyethylene glycol segments.

[0019] As a preferred technical solution of the present invention, in S1, the mass ratio of citric acid, urea and deionized water is (10-15):(3-6):(30-60), for example, it can be (10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5 or 15.0):(3.0, 3.3, 3.6, 3.9, 4.2, 4.5, 4.8, 5.1, 5.4, 5.7 or 6.0):(30, 33, 36, 39, 42, 45, 48, 51, 54, 57 or 60), but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0020] In some alternative embodiments, the first temperature is 180-200°C, for example, it can be 180°C, 182°C, 184°C, 186°C, 188°C, 190°C, 192°C, 194°C, 196°C, 198°C or 200°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0021] In some optional embodiments, the hydrothermal reaction time at the first temperature is 6-8 hours, for example, 6.0 hours, 6.2 hours, 6.4 hours, 6.6 hours, 6.8 hours, 7.0 hours, 7.2 hours, 7.4 hours, 7.6 hours, 7.8 hours, or 8.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0022] In some optional embodiments, the dialysis bag has a molecular weight cutoff of 3500 Da, the replacement solution is deionized water, and the time is 24-48 h, for example, 24 h, 26.4 h, 28.8 h, 31.2 h, 33.6 h, 36 h, 38.4 h, 40.8 h, 43.2 h, 45.6 h, or 48 h, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0023] In some optional embodiments, the mass ratio of tetraisopropyl titanate, anhydrous ethanol, urea solution, carbon dots, and glacial acetic acid is (18-24):(180-240):(28-55):(0.5-1.5):(0.5-1), for example, it can be (18, 18.6, 19.2, 19.8, 20.4, 21, 21.6, 22.2, 22.8, 23.4, or 24):(180, 186, 192, 198, 204, 210, 216, 222, 228, 234, or 24). 0): (28, 30.7, 33.4, 36.1, 38.8, 41.5, 44.2, 46.9, 49.6, 52.3 or 55): (0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5): (0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95 or 1.0), but not limited to the listed values; other unlisted values ​​within this range also apply.

[0024] In some optional embodiments, the mass fraction of the urea solution is 17-42 wt.%; for example, it can be 17 wt.%, 19.5 wt.%, 22 wt.%, 24.5 wt.%, 27 wt.%, 29.5 wt.%, 32 wt.%, 34.5 wt.%, 37 wt.%, 39.5 wt.%, or 42 wt.%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0025] In some alternative embodiments, the second temperature is 160-180°C, for example, it can be 160°C, 162°C, 164°C, 166°C, 168°C, 170°C, 172°C, 174°C, 176°C, 178°C or 180°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0026] In some optional embodiments, the hydrothermal reaction time at the second temperature is 6-8 hours, for example, 6.0 hours, 6.2 hours, 6.4 hours, 6.6 hours, 6.8 hours, 7.0 hours, 7.2 hours, 7.4 hours, 7.6 hours, 7.8 hours, or 8.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0027] In some alternative embodiments, the third temperature is 380-420°C, for example, it can be 380°C, 384°C, 388°C, 392°C, 396°C, 400°C, 404°C, 408°C, 412°C, 416°C or 420°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0028] In some optional embodiments, the calcination time is 1.5-2.5h, for example, it can be 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2.0h, 2.1h, 2.2h, 2.3h, 2.4h or 2.5h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0029] As a preferred embodiment of the present invention, in S2, the N-TiO2@CDs, anhydrous toluene, 3-mercaptopropyltrimethoxysilane, glacial acetic acid, ethylene glycol, and PVP are... The mass ratio of K30 to silver nitrate is (5-8):(150-250):(1-2):(0.2-0.5):(90-140):(0.05-0.2):(0.15-0.4), for example, it can be (5.0, 5.3, 5.6, 5.9, 6.2, 6.5, 6.8, 7.1, 7.4, 7.7 or 8.0):(150, 160, 170, 180, 190, 200, 210, 220, 230, 240 or 250):(1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2.0):(0.2, 0.23, 0.26, 0. 0.29, 0.32, 0.35, 0.38, 0.41, 0.44, 0.47 or 0.5: (90, 95, 100, 105, 110, 115, 120, 125, 130, 135 or 140): (0.05, 0.065, 0.08, 0.095, 0.11, 0.125, 0.14, 0.155, 0.17, 0.185 or 0.2): (0.15, 0.175, 0.2, 0.225, 0.25, 0.275, 0.3, 0.325, 0.35, 0.375 or 0.4), but not limited to the listed values; other unlisted values ​​within this range also apply.

[0030] In some alternative embodiments, the fourth temperature is 70-80°C, for example, it can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0031] In some alternative embodiments, the reflux reaction time is 3-5 hours, for example, 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4.0 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours, or 5.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0032] In some optional embodiments, the fifth temperature is 150-165°C, for example, it can be 150°C, 151.5°C, 153°C, 154.5°C, 156°C, 157.5°C, 159°C, 160.5°C, 162°C, 163.5°C or 165°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0033] In some optional embodiments, the reduction reaction time is 20-40 min, for example, 20 min, 22 min, 24 min, 26 min, 28 min, 30 min, 32 min, 34 min, 36 min, 38 min or 40 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0034] As a preferred technical solution of the present invention, in S3, the mass ratio of activated carbon to nitric acid is (50-100):(500-800), for example, it can be (50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 100):(500, 530, 560, 590, 620, 650, 680, 710, 740, 770 or 800), but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0035] In some alternative embodiments, the mass fraction of the nitric acid is 10-20 wt.%, for example, it can be 10 wt.%, 11 wt.%, 12 wt.%, 13 wt.%, 14 wt.%, 15 wt.%, 16 wt.%, 17 wt.%, 18 wt.%, 19 wt.%, or 20 wt.%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0036] In some optional embodiments, the carbonate buffer solution has a concentration of 0.1 M and a pH of 7.8-8.3.

[0037] In some alternative embodiments, the sixth temperature is 70-85°C, for example, it can be 70°C, 71.5°C, 73°C, 74.5°C, 76°C, 77.5°C, 79°C, 80.5°C, 82°C, 83.5°C or 85°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0038] In some optional embodiments, the stirring time is 3-5 hours, for example, 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4.0 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours or 5.0 hours, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0039] In some optional embodiments, the mass ratio of the oxidizing activated carbon, the aqueous ethanol solution, 3-aminopropyltriethoxysilane, and deionized water is (20-40):(200-400):(2-5):(0.5-1.5), for example, it can be (20, 22, 24, 26, 28, 30, 32, 34, 36, 38, or 40):(200, 220, 240, 260, 280, 300). 320, 340, 360, 380 or 400: (2.0, 2.3, 2.6, 2.9, 3.2, 3.5, 3.8, 4.1, 4.4, 4.7 or 5.0): (0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5), but not limited to the listed values; other unlisted values ​​within this range also apply.

[0040] In some optional embodiments, the volume ratio of ethanol to deionized water in the aqueous ethanol solution is 95:5.

[0041] In some optional embodiments, the pre-hydrolysis time is 20-40 min, for example, it can be 20 min, 22 min, 24 min, 26 min, 28 min, 30 min, 32 min, 34 min, 36 min, 38 min or 40 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0042] In some optional embodiments, the seventh temperature is 70-80°C, for example, it can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0043] In some optional embodiments, the humidity of the hygrothermal curing is 50-70%RH and the temperature is 80-100℃. For example, the humidity can be (50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68% or 70%)RH and the temperature can be (80, 82, 84, 86, 88, 90, 92, 94, 96, 98 or 100)℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] In some optional embodiments, the humid heat curing time is 1-2 hours, for example, it can be 1.0 hours, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0045] In some optional embodiments, the mass ratio of the aminated activated carbon, carbonate buffer solution, and active ester polyethylene glycol maleimide is (10-20):(150-300):(0.5-1.5), for example, it can be (10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20):(150, 165, 180, 195, 210, 225, 240, 255, 270, 285 or 300):(0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5), but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0046] In some optional embodiments, the molecular weight of polyethylene glycol in the active ester polyethylene glycol maleimide is 3400.

[0047] In some optional embodiments, the room temperature reaction time is 0.5-1.5 h, for example, it can be 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1.0 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h or 1.5 h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0048] As a preferred technical solution of the present invention, in S4, the mass ratio of Ag@(N-TiO2@CDs-SH) powder, phosphate buffer, and maleimide-activated carbon is (5-10):(150-300):(5-10), for example, it can be (5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 or 10):(150, 165, 180, 195, 210, 225, 240, 255, 270, 285 or 300):(5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 or 10), but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0049] In some alternative embodiments, the room temperature reaction time is 2-4 hours, for example, 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, or 4.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0050] Secondly, the present invention provides an antibacterial activated carbon-silver ion composite photocatalyst prepared by the preparation method described in the first aspect.

[0051] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention adopts a stepwise synthesis and post-composite strategy, which avoids the blockage and damage to the pore structure caused by in-situ growth of functional components in the activated carbon pores, and maximizes the preservation of the inherent well-developed pore structure and excellent physical adsorption capacity of activated carbon. Covalent bonds are formed between functional nanoparticles and activated carbon carrier, which effectively prevents the functional components from falling off during use. The present invention, through the synergistic effect of nitrogen doping and carbon dot sensitization, enables the photocatalyst to have a broad spectrum response characteristics, which can effectively utilize indoor visible light. Through the bridging of heterobifunctional crosslinking agents, the catalytic active sites are fully exposed, and the adsorption function and catalytic degradation function are highly efficient and synergistic, thus improving the overall removal efficiency and antibacterial performance of the material for pollutants. Detailed Implementation

[0052] 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.

[0053] 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.

[0054] Example 1

[0055] This embodiment provides an antibacterial activated carbon-silver ion composite photocatalyst and its preparation method. The preparation method specifically includes the following steps:

[0056] S1, 10g of citric acid and 6g of urea were dispersed in 30g of deionized water and then transferred to a hydrothermal reactor. The mixture was hydrothermally reacted at 200℃ for 6h, cooled, centrifuged, dialyzed, and freeze-dried. The molecular weight cutoff of the dialysis bag was 3500Da, the replacement solution was deionized water, and the reaction time was 48h. Carbon dots were obtained. 18g of tetraisopropyl titanate was dissolved in 240g of anhydrous ethanol. Under ice bath conditions, 55g of 17wt.% urea solution, 0.5g of carbon dots, and 1g of glacial acetic acid were added. The mixture was hydrothermally reacted at 180℃ for 6h, centrifuged, washed, and dried to obtain N-TiO2@CDs precursor. Under a nitrogen atmosphere, the N-TiO2@CDs precursor was calcined at 420℃ for 1.5h to obtain N-TiO2@CDs.

[0057] S2, 5g of N-TiO2@CDs were dispersed in 250g of anhydrous toluene, 2g of 3-mercaptopropyltrimethoxysilane and 0.2g of glacial acetic acid were added, and the mixture was refluxed at 80℃ for 3h under nitrogen protection. After cooling, washing and drying, N-TiO2@CDs-SH was obtained and dispersed in 90g of ethylene glycol. 0.20g of PVP K30 and 0.15g of silver nitrate were added, and the mixture was reduced at 165℃ for 20min under nitrogen protection. After quenching in an ice-water bath, the mixture was washed until no silver ions were found in the supernatant and dried to obtain Ag@(N-TiO2@CDs-SH) powder.

[0058] S3, 100g of activated carbon is added to 500g of 20wt.% nitric acid, stirred at 85℃ for 3h, poured out, washed with deionized water until the pH of the washing solution reaches 6, and dried to obtain oxidized activated carbon. 40g of oxidized activated carbon is dispersed in 200g of ethanol aqueous solution, wherein the volume ratio of ethanol to deionized water in the ethanol aqueous solution is 95:5, and 2g of... 3-Aminopropyltriethoxysilane was pre-hydrolyzed with 1.5g of deionized water in an ice bath for 40 min, and then reacted at 80℃ for 3 h under a nitrogen atmosphere. After filtration, washing, and drying, the mixture was then cured by humid heat for 2 h at a humidity of 50%RH and a temperature of 100℃ to obtain aminated activated carbon. 20g of the aminated activated carbon was dispersed in 150g of carbonate buffer solution with a concentration of 0.1M and a pH of 7.8. 0.5g of active ester polyethylene glycol maleimide was added, wherein the molecular weight of polyethylene glycol in the active ester polyethylene glycol maleimide was 3400. The mixture was reacted at room temperature for 1.5 h, and then filtered, washed, and dried to obtain maleimide-activated carbon.

[0059] S4. 10g Ag@(N-TiO2@CDs-SH) powder was dispersed in 150g phosphate buffer, and 5g maleimide-activated carbon was added. The mixture was protected from light by nitrogen and reacted at room temperature for 4h. After filtration, washing and drying, an antibacterial activated carbon-silver ion composite photocatalyst was obtained.

[0060] Example 2

[0061] This embodiment provides an antibacterial activated carbon-silver ion composite photocatalyst and its preparation method. The preparation method specifically includes the following steps:

[0062] S1, 15g of citric acid and 3g of urea were dispersed in 60g of deionized water and then transferred to a hydrothermal reactor. The mixture was hydrothermally reacted at 180℃ for 8h, followed by cooling, centrifugation, dialysis, and freeze-drying. The molecular weight cutoff of the dialysis bag was 3500Da, the replacement solution was deionized water, and the reaction time was 24h. Carbon dots were obtained. 24g of tetraisopropyl titanate was dissolved in 180g of anhydrous ethanol. Under ice bath conditions, 28g of urea solution with a mass fraction of 42wt.%, 1.5g of carbon dots, and 0.5g of glacial acetic acid were added. The mixture was hydrothermally reacted at 160℃ for 8h, followed by centrifugation, washing, and drying to obtain N-TiO2@CDs precursor. Under a nitrogen atmosphere, the N-TiO2@CDs precursor was calcined at 380℃ for 2.5h to obtain N-TiO2@CDs.

[0063] S2, 8g of N-TiO2@CDs were dispersed in 150g of anhydrous toluene, 1g of 3-mercaptopropyltrimethoxysilane and 0.5g of glacial acetic acid were added, and the mixture was refluxed at 70℃ for 5h under nitrogen protection. After cooling, washing and drying, N-TiO2@CDs-SH was obtained and dispersed in 140g of ethylene glycol. 0.05g of PVP K30 and 0.40g of silver nitrate were added, and the mixture was reduced at 150℃ for 40min under nitrogen protection. After quenching in an ice-water bath, the mixture was washed until no silver ions were found in the supernatant and dried to obtain Ag@(N-TiO2@CDs-SH) powder.

[0064] S3, 50g of activated carbon was added to 800g of 10wt.% nitric acid, stirred at 70℃ for 5h, poured out, washed with deionized water until the pH of the washing solution reached 6.3, and dried to obtain oxidized activated carbon. 20g of oxidized activated carbon was dispersed in 400g of ethanol aqueous solution, wherein the volume ratio of ethanol to deionized water in the ethanol aqueous solution was 95:5, and 5g of... 3-Aminopropyltriethoxysilane was pre-hydrolyzed with 0.5g of deionized water in an ice bath for 20 min, and then reacted at 70℃ for 5 h under a nitrogen atmosphere. After filtration, washing, and drying, the mixture was then cured by humid heat for 1 h at a humidity of 70%RH and a temperature of 80℃ to obtain aminated activated carbon. 10g of the aminated activated carbon was dispersed in 300g of carbonate buffer solution with a concentration of 0.1M and a pH of 8.3. 1.5g of active ester polyethylene glycol maleimide was added, wherein the molecular weight of polyethylene glycol in the active ester polyethylene glycol maleimide was 3400. The mixture was reacted at room temperature for 0.5 h, and then filtered, washed, and dried to obtain maleimide-activated carbon.

[0065] S4. 5g Ag@(N-TiO2@CDs-SH) powder was dispersed in 300g phosphate buffer, and 10g maleimide-activated carbon was added. The mixture was protected from light by nitrogen and reacted at room temperature for 2 h. After filtration, washing and drying, an antibacterial activated carbon-silver ion composite photocatalyst was obtained.

[0066] Example 3

[0067] This embodiment provides an antibacterial activated carbon-silver ion composite photocatalyst and its preparation method. The preparation method specifically includes the following steps:

[0068] S1, 12g of citric acid and 4g of urea were dispersed in 45g of deionized water and then transferred to a hydrothermal reactor. The mixture was hydrothermally reacted at 190℃ for 7h, followed by cooling, centrifugation, dialysis, and freeze-drying. The molecular weight cutoff of the dialysis bag was 3500Da, the replacement solution was deionized water, and the reaction time was 36h. Carbon dots were obtained. 20g of tetraisopropyl titanate was dissolved in 200g of anhydrous ethanol. Under ice bath conditions, 40g of 30wt.% urea solution, 1.0g of carbon dots, and 0.8g of glacial acetic acid were added. The mixture was hydrothermally reacted at 170℃ for 7h, followed by centrifugation, washing, and drying to obtain N-TiO2@CDs precursor. Under a nitrogen atmosphere, the N-TiO2@CDs precursor was calcined at 400℃ for 2.0h to obtain N-TiO2@CDs.

[0069] S2, 6g of N-TiO2@CDs were dispersed in 200g of anhydrous toluene, 1.5g of 3-mercaptopropyltrimethoxysilane and 0.4g of glacial acetic acid were added, and the mixture was refluxed at 75℃ for 4h under nitrogen protection. After cooling, washing and drying, N-TiO2@CDs-SH was obtained and dispersed in 110g of ethylene glycol. 0.12g of PVP K30 and 0.30g of silver nitrate were added, and the mixture was reduced at 158℃ for 30min under nitrogen protection. After quenching in an ice-water bath, the mixture was washed until no silver ions were found in the supernatant and dried to obtain Ag@(N-TiO2@CDs-SH) powder.

[0070] S3, 80g of activated carbon was added to 600g of 15wt.% nitric acid, stirred at 80℃ for 4h, poured out, washed with deionized water until the pH of the washing solution reached 7, and dried to obtain oxidized activated carbon. 30g of oxidized activated carbon was dispersed in 300g of ethanol aqueous solution, wherein the volume ratio of ethanol to deionized water in the ethanol aqueous solution was 95:5, and 3.5g of [unspecified ingredient] was added. 3-Aminopropyltriethoxysilane was pre-hydrolyzed with 1.0 g of deionized water in an ice bath for 30 min, and then reacted at 75 °C for 4 h under a nitrogen atmosphere. After filtration, washing, and drying, the mixture was then cured by humid heat for 1.5 h at a humidity of 60% RH and a temperature of 90 °C to obtain aminated activated carbon. 15 g of the aminated activated carbon was dispersed in 220 g of carbonate buffer solution with a concentration of 0.1 M and a pH of 8.0. 1.0 g of active ester polyethylene glycol maleimide was added, wherein the molecular weight of polyethylene glycol in the active ester polyethylene glycol maleimide was 3400. The mixture was reacted at room temperature for 1.0 h, and then filtered, washed, and dried to obtain maleimide-activated carbon.

[0071] S4. 8g of Ag@(N-TiO2@CDs-SH) powder was dispersed in 200g of phosphate buffer, and 8g of maleimide-activated carbon was added. The mixture was protected from light by nitrogen and reacted at room temperature for 3h. After filtration, washing and drying, an antibacterial activated carbon-silver ion composite photocatalyst was obtained.

[0072] Example 4

[0073] This embodiment provides an antibacterial activated carbon-silver ion composite photocatalyst and its preparation method. The preparation method specifically includes the following steps:

[0074] S1, 14g of citric acid and 5g of urea were dispersed in 50g of deionized water and transferred to a hydrothermal reactor. The mixture was hydrothermally reacted at 195℃ for 7.5h, cooled, centrifuged, dialyzed, and freeze-dried. The molecular weight cutoff of the dialysis bag was 3500Da, the replacement solution was deionized water, and the reaction time was 30h. Carbon dots were obtained. 22g of tetraisopropyl titanate was dissolved in 220g of anhydrous ethanol. Under ice bath conditions, 45g of urea solution with a mass fraction of 25wt.%, 1.2g of carbon dots, and 0.7g of glacial acetic acid were added. The mixture was hydrothermally reacted at 175℃ for 7.5h, centrifuged, washed, and dried to obtain N-TiO2@CDs precursor. Under a nitrogen atmosphere, the N-TiO2@CDs precursor was calcined at 410℃ for 2.2h to obtain N-TiO2@CDs.

[0075] S2, 7g of N-TiO2@CDs were dispersed in 180g of anhydrous toluene, 1.8g of 3-mercaptopropyltrimethoxysilane and 0.3g of glacial acetic acid were added, and the mixture was refluxed at 78℃ for 4.5h under nitrogen protection. After cooling, washing and drying, N-TiO2@CDs-SH was obtained and dispersed in 120g of ethylene glycol. 0.18g of PVP K30 and 0.25g of silver nitrate were added, and the mixture was reduced at 160℃ for 35min under nitrogen protection. After quenching in an ice-water bath, the mixture was washed until the supernatant was free of silver ions and dried to obtain Ag@(N-TiO2@CDs-SH) powder.

[0076] S3, 60g of activated carbon was added to 700g of nitric acid (18wt.%), stirred at 75℃ for 4.5h, poured off, washed with deionized water until the pH of the washing solution reached 6.7, and dried to obtain oxidized activated carbon. 35g of the oxidized activated carbon was dispersed in 350g of an ethanol-water solution (ethanol to deionized water volume ratio 95:5), 4g of 3-aminopropyltriethoxysilane and 1.2g of deionized water were added, and the mixture was pre-hydrolyzed in an ice bath for 35min. The reaction was then carried out at 72℃ for 4.5h under a nitrogen atmosphere. h, filter, wash, dry, and then moist heat cure for 1.8h, the humidity of the moist heat curing is 65%RH and the temperature is 85℃, to obtain aminated activated carbon. 18g of aminated activated carbon is dispersed in 280g of carbonate buffer solution, the concentration of the carbonate buffer solution is 0.1M and the pH is 8.1, and 1.2g of active ester polyethylene glycol maleimide is added, the molecular weight of polyethylene glycol in the active ester polyethylene glycol maleimide is 3400, react at room temperature for 1.2h, filter, wash, and dry to obtain maleimide-activated carbon;

[0077] S4. 6g Ag@(N-TiO2@CDs-SH) powder was dispersed in 250g phosphate buffer, and 6g maleimide-activated carbon was added. The mixture was protected from light by nitrogen and reacted at room temperature for 2.5 h. After filtration, washing, and drying, an antibacterial activated carbon-silver ion composite photocatalyst was obtained.

[0078] Comparative Example 1

[0079] This comparative example provides an antibacterial activated carbon-silver ion composite photocatalyst and its preparation method. The difference between this example and Example 1 is that the aminated activated carbon in S3 does not react with the activated ester polyethylene glycol maleimide. Instead, an equal mass of aminated activated carbon is used to replace the maleimide-activated carbon in S4. Other process parameters and operating conditions are exactly the same as in Example 1.

[0080] Comparative Example 2

[0081] This comparative example provides an antibacterial activated carbon-silver ion composite photocatalyst and its preparation method. The difference between this example and Example 1 is that no thiol functional groups are grafted in S2. Instead, N-TiO2@CDs are directly reacted with PVP K30 and silver nitrate. Other process parameters and operating conditions are exactly the same as in Example 1.

[0082] Comparative Example 3

[0083] This comparative example provides an antibacterial activated carbon-silver ion composite photocatalyst and its preparation method. The difference between this example and Example 1 is that the mass of silver nitrate in S2 is 0, and the subsequent steps all use products without nano-silver loading as reactants. Other process parameters and operating conditions are exactly the same as in Example 1.

[0084] The performance of the antibacterial activated carbon-silver ion composite photocatalysts prepared in Examples 1-4 and Comparative Examples 1-3 was tested, and the specific process is as follows:

[0085] The formaldehyde removal rate test method is GB / T23761-2020; the antibacterial performance test method is GB / T21510-2024; and the specific surface area test method is GB / T19587-2017. The test results are shown in Table 1.

[0086] Table 1. Performance test results of antibacterial activated carbon-silver ion composite photocatalysts prepared in Examples 1-4 and Comparative Examples 1-3

[0087]

[0088] As shown in Table 1, compared to Example 1, Comparative Example 1 showed a decrease in formaldehyde removal rate, antibacterial rate, and specific surface area; Comparative Example 2 showed a decrease in formaldehyde removal rate, antibacterial rate, and specific surface area; and Comparative Example 3 showed a decrease in formaldehyde removal rate, antibacterial rate, and specific surface area. This is because, in Comparative Example 1, the aminated activated carbon did not react with the activated ester polyethylene glycol maleimide, and the nanoparticles could not be fixed on the activated carbon carrier through the Michael addition reaction. The nanoparticles were bound by physical adsorption, which easily led to agglomeration at the pore openings, causing blockage of some pores and a small effective catalytic surface area. At the same time, the nanoparticles were not firmly bound, thus Comparative Example 1 showed a decrease in formaldehyde removal rate, antibacterial rate, and specific surface area. In Comparative Example 2, without grafting thiol functional groups, the direct reaction of N-TiO2@CDs with PVP K30 and silver nitrate failed to form covalent bonds. This resulted in weak binding between the nanoparticles and the carrier, and the physically adsorbed particles also aggregated and clogged the pores, leading to a decrease in formaldehyde removal rate, antibacterial rate, and specific surface area. In Comparative Example 3, the mass of silver nitrate was zero, failing to provide a good antibacterial effect. Furthermore, its photogenerated electron-hole recombination rate increased, resulting in a decrease in both formaldehyde removal rate and antibacterial rate.

[0089] 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 an antibacterial activated carbon-silver ion composite photocatalyst, characterized in that, The preparation method includes: S1, citric acid and urea are dispersed in deionized water and reacted to obtain carbon dots. Tetraisopropyl titanate is dissolved in anhydrous ethanol, and urea solution, carbon dots and glacial acetic acid are added to react to obtain N-TiO2@CDs precursor. Under nitrogen atmosphere, N-TiO2@CDs precursor is calcined to obtain N-TiO2@CDs. S2, N-TiO2@CDs are dispersed in anhydrous toluene, 3-mercaptopropyltrimethoxysilane is added and reacted with glacial acetic acid to obtain N-TiO2@CDs-SH, which is then dispersed in ethylene glycol. PVP K30 is added and reacted with silver nitrate to obtain Ag@(N-TiO2@CDs-SH) powder; S3, add activated carbon to nitric acid and stir to obtain oxidized activated carbon. Disperse the oxidized activated carbon in an ethanol aqueous solution, add 3-aminopropyltriethoxysilane and react with deionized water to obtain aminated activated carbon. Disperse the aminated activated carbon in a carbonate buffer solution, add active ester polyethylene glycol maleimide to obtain maleimide-activated carbon. S4. Ag@(N-TiO2@CDs-SH) powder was dispersed in phosphate buffer, and maleimide-activated carbon was added to react and an antibacterial activated carbon-silver ion composite photocatalyst was obtained.

2. The method for preparing an antibacterial activated carbon-silver ion composite photocatalyst according to claim 1, characterized in that, In S1: The mass ratio of citric acid, urea and deionized water is (10-15):(3-6):(30-60).

3. The method for preparing an antibacterial activated carbon-silver ion composite photocatalyst according to claim 1, characterized in that, In S1: The mass ratio of tetraisopropyl titanate, anhydrous ethanol, urea solution, carbon dots and glacial acetic acid is (18-24):(180-240):(28-55):(0.5-1.5):(0.5-1).

4. The method for preparing an antibacterial activated carbon-silver ion composite photocatalyst according to claim 1, characterized in that, In S2: The mass ratio of N-TiO2@CDs, anhydrous toluene, 3-mercaptopropyltrimethoxysilane, glacial acetic acid, ethylene glycol, PVP K30 and silver nitrate is (5-8):(150-250):(1-2):(0.2-0.5):(90-140):(0.05-0.2):(0.15-0.4).

5. The method for preparing an antibacterial activated carbon-silver ion composite photocatalyst according to claim 1, characterized in that, In S3: The mass fraction of the nitric acid is 10-20 wt.%. The mass ratio of activated carbon to nitric acid is (50-100):(500-800).

6. The method for preparing an antibacterial activated carbon-silver ion composite photocatalyst according to claim 1, characterized in that, In S3: The mass ratio of the oxidizing activated carbon, ethanol aqueous solution, 3-aminopropyltriethoxysilane and deionized water is (20-40):(200-400):(2-5):(0.5-1.5).

7. The method for preparing an antibacterial activated carbon-silver ion composite photocatalyst according to claim 1, characterized in that, In S3: The mass ratio of the aminated activated carbon, carbonate buffer solution and active ester polyethylene glycol maleimide is (10-20):(150-300):(0.5-1.5).

8. The method for preparing an antibacterial activated carbon-silver ion composite photocatalyst according to claim 1, characterized in that, In S3: The carbonate buffer solution has a concentration of 0.1 M and a pH of 7.8-8.3; The molecular weight of polyethylene glycol in the active ester polyethylene glycol maleimide is 3400.

9. The method for preparing an antibacterial activated carbon-silver ion composite photocatalyst according to claim 1, characterized in that, In S4: The mass ratio of Ag@(N-TiO2@CDs-SH) powder, phosphate buffer, and maleimide-activated carbon is (5-10):(150-300):(5-10).

10. An antibacterial activated carbon-silver ion composite photocatalyst obtained by the preparation method according to any one of claims 1-9.

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