Filter element, preparation method thereof and water purifying device

Abstract

The invention relates to the technical field of water purifiers, in particular to a filter element, a preparation method of the filter element and a water purifying device.The filter element comprises a silica sand layer, an activated carbon adsorption layer and a modified nano-silver functional layer which are stacked in the water flow direction; wherein the modified nano-silver functional layer comprises nano-silver particles modified by antibacterial peptide-cyclodextrin. According to the filter element prepared through the method, a superfine and dispersed nano-silver particle system is constructed, the stability of nano-silver in the filter element system can be greatly enhanced, then the antibacterial activity and antibacterial broad-spectrum performance of the nano-silver are improved, meanwhile, efficient removal of heavy metal is achieved in an auxiliary mode, and the water purification efficiency of a water purification device is effectively and comprehensively improved.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, specifically to a filter cartridge and its preparation method, and a water purification device. Background Technology

[0002] In the field of water treatment, especially in the research and application of water purifiers, the complex water quality scenarios where multiple types of pollutants coexist and the functional limitations of single filter materials have become the core technical challenges restricting the improvement of purification effects. Actual water bodies often contain multiple pollutants simultaneously, including suspended particles (such as silt and rust), colloids, dissolved organic matter, harmful microorganisms (bacteria, viruses, etc.), heavy metal ions, and residual chlorine. Highly efficient purification technologies are needed to achieve the synergistic removal of these multiple pollutants to meet drinking water safety standards.

[0003] The single filter materials commonly used in existing water purifiers all have significant functional shortcomings:

[0004] As a traditional filter medium, silica sand (quartz sand) mainly relies on mechanical interception for its purification mechanism. It can only effectively remove large suspended solids in water, but it cannot effectively intercept or remove smaller colloids, dissolved organic matter and microorganisms, resulting in insufficient purification depth.

[0005] Activated carbon, with its high specific surface area (usually ≥1000 m² / g) and physical adsorption properties, can specifically remove residual chlorine (adsorption efficiency ≥90%), volatile organic compounds (VOCs), and some water pigments. However, the pore structure of this material is easily blocked by suspended solids in the water, resulting in a rapid decrease in filtration flux. It also lacks the ability to inactivate microorganisms and cannot remove dissolved heavy metal ions.

[0006] Nano silver, as a typical antibacterial functional material, can destroy the cell structure of bacteria (such as Escherichia coli and Legionella) and viruses (such as norovirus) by releasing Ag⁺ (effective release concentration is 0.01~0.1mg / L), with a bactericidal rate of up to 99.9%. However, when used alone, it requires extremely high pretreatment of particulate matter and organic matter in the water, and nano silver is easily encapsulated by suspended matter and loses its antibacterial activity, which limits its practical application.

[0007] To compensate for the shortcomings of single materials, most existing water purifier products adopt combined filtration technology, but they generally have design flaws: most products simply stack a silica sand filter layer and an activated carbon filter layer (i.e., "sand filter + carbon filter" mode), without solving the problem of suspended solids clogging the pores of activated carbon, resulting in a shortened overall lifespan of the filter element; some products blindly mix nano-silver and activated carbon without solving the problem of uniform distribution of nano-silver in the activated carbon matrix. This not only fails to give full play to the synergistic effect of antibacterial and adsorption, but may also cause secondary pollution risks due to the growth of microorganisms in the pores of activated carbon, making it difficult to achieve efficient and stable removal of multiple types of pollutants.

[0008] Therefore, developing a water purifier technology that can overcome the limitations of existing materials and the defects of combination technology to achieve the synergistic purification of multiple pollutants such as suspended particles, colloids, organic matter, microorganisms, heavy metals and residual chlorine has become the key to improving water purification efficiency. Summary of the Invention

[0009] This invention provides a filter cartridge and its preparation method, as well as a water purification device. The filter cartridge employs a layered structure design of a silica sand layer, an activated carbon layer, and a modified nano-silver functional layer. This constructs a purification system that combines graded purification with synergistic effects. The silica sand layer intercepts large particulate pollutants, the activated carbon layer specifically adsorbs small molecule pollutants, and the modified nano-silver functional layer is formed by modification with antimicrobial peptides and cyclodextrin. This modification technology not only significantly reduces the nano-silver particle size, constructing an ultrafine and dispersed nano-silver particle system, but also greatly enhances the stability of nano-silver in the filter cartridge system, thereby improving its antibacterial activity and broad-spectrum antibacterial properties. Simultaneously, it assists in the efficient removal of heavy metals, effectively and comprehensively improving the water purification efficiency of the water purification device.

[0010] In a first aspect, the present invention provides a filter cartridge comprising a silica sand layer, an activated carbon adsorption layer, and a modified nano-silver functional layer stacked along the water flow direction; wherein the modified nano-silver functional layer comprises nano-silver particles modified with antimicrobial peptide-cyclodextrin.

[0011] Furthermore, the silica sand layer is made of at least one of natural quartz sand and modified silica sand.

[0012] Furthermore, the natural quartz sand has a particle size of 0.5~1.2mm and a SiO2 content of ≥99%.

[0013] Furthermore, the modified silica sand is selected from silica sand with iron oxide loaded on its surface. The iron oxide on its surface can enhance the initial adsorption of colloids and some heavy metals.

[0014] The silica sand layer mechanically removes large suspended particles such as silt, rust, and algae from the water, as well as colloids with particle sizes ranging from 1 to 100 μm and some humic substances, protecting the subsequent activated carbon layer from physical clogging. The silica sand layer can intercept more than 90% of particles larger than 50 μm, thereby extending the service life of the activated carbon adsorption layer by more than 30%.

[0015] Furthermore, the material of the activated carbon adsorption layer is at least one of coconut shell activated carbon with an iodine value ≥1000 mg / g and modified activated carbon.

[0016] Furthermore, the modified activated carbon is selected from activated carbon supported on transition metal oxides.

[0017] Furthermore, the transition metal oxide is selected from MnO2 and / or CuO to enhance the resistance to heavy metal ions Pb²⁺, Hg²⁺, and Cr. 6 ⁺ chemical adsorption.

[0018] Preferably, the activated carbon is in the form of granules with a particle size of 0.8~1.5mm.

[0019] Preferably, the activated carbon is a honeycomb compressed block with a specific surface area ≥1200 m² / g.

[0020] Furthermore, the antimicrobial peptide-cyclodextrin modified silver nanoparticles have a particle size of 10~20 nm.

[0021] Preferably, the thickness ratio of the silica sand layer to the activated carbon adsorption layer is 1:(1~1.6).

[0022] Preferably, the nano-silver particles account for 0.2~0.5 wt% of the modified nano-silver functional layer.

[0023] The activated carbon adsorption layer can remove more than 95% of residual chlorine, 80% of small molecule organic compounds such as benzene and aldehydes, and some pigments through physical adsorption; at the same time, as a pretreatment unit for the modified nano-silver functional layer, it can reduce the interference of organic matter on the activity of nano-silver.

[0024] Secondly, the present invention provides a method for preparing the above-mentioned filter element, comprising the following steps:

[0025] S1. Fill with a layer of silica sand;

[0026] S2. Fill the silica sand layer of S1 with an activated carbon adsorption layer;

[0027] S3. Preparation of modified silver nanolayer functional layer:

[0028] Preparation of antimicrobial peptide-cyclodextrin solution: Add antimicrobial peptide solution to cyclodextrin solution, stir, let stand, centrifuge to collect supernatant, freeze dry to obtain antimicrobial peptide-cyclodextrin inclusion complex, dissolve the antimicrobial peptide-cyclodextrin inclusion complex in water to obtain antimicrobial peptide-cyclodextrin solution;

[0029] Preparation of antimicrobial peptide-cyclodextrin modified silver nanoparticles: Silver nitrate solution was added to the antimicrobial peptide-cyclodextrin solution at 50~80℃, the pH value was adjusted to 9~12, and the reaction was stirred to obtain antimicrobial peptide-cyclodextrin modified silver nanoparticles.

[0030] Preparation of modified silver nanoparticle functional layer: The antimicrobial peptide-cyclodextrin modified silver nanoparticles are coated on the surface of a carrier to form a modified silver nanoparticle coating. The modified silver nanoparticle functional layer formed by the carrier loaded with the modified silver nanoparticle coating is then placed on the activated carbon adsorption layer.

[0031] Furthermore, in S3, the molar ratio of the antimicrobial peptide-cyclodextrin inclusion complex to silver nitrate is [missing information].

[0032] (5~15):1.

[0033] Furthermore, the reaction time between the antimicrobial peptide-cyclodextrin inclusion complex and silver nitrate is 1~10h.

[0034] Furthermore, in S3, the molar ratio of antimicrobial peptide to cyclodextrin is 1:(5~20).

[0035] Furthermore, in step S3, the pH is adjusted to 9-12 using a sodium hydroxide solution.

[0036] Furthermore, the concentration of the sodium hydroxide solution is 0.5~5 mol / L.

[0037] Furthermore, in step S3, the stirring can be performed using mechanical stirring or ultrasonic stirring.

[0038] Furthermore, in step S3, the settling time is 24~36 hours.

[0039] Furthermore, in step S4, the centrifugation speed is 10000~12000 rpm, and the centrifugation time is 10~25 min.

[0040] Furthermore, the carrier is an activated carbon adsorption layer or a porous ceramic carrier.

[0041] Furthermore, the silver content in the nano-silver coating is 0.2~0.5wt%.

[0042] The antimicrobial peptides used in this invention can be commercially available conventional antimicrobial peptides; the cyclodextrins used in this invention can be common cyclodextrins, preferably β-cyclodextrin, α-cyclodextrin, or γ-cyclodextrin.

[0043] Thirdly, the present invention also provides a water purification device, including the above-mentioned filter element, or including the filter element prepared by the above-mentioned filter element preparation method.

[0044] Specifically, in some embodiments of the present invention, the water purification device further includes a housing, which has an inlet and an outlet. The inlet is used to connect to municipal water supply, and the outlet is used to connect to a faucet. The silica sand layer, activated carbon adsorption layer, and modified nano-silver functional layer are sequentially encapsulated in the housing to form the water purification device.

[0045] Specifically, in some embodiments of the present invention, a pressure detector is installed on the water purification device to detect pressure changes within the water purification device in real time.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] This invention provides a composite filter cartridge and its preparation method, as well as a water purification device, through a dual-dimensional design of "material modification + structural innovation": On the one hand, it uses antimicrobial peptide-cyclodextrin as a modifier, combined with silver nitrate and water, and synthesizes ultrafine and dispersed nano-silver particles by adjusting the pH value with sodium hydroxide; on the other hand, it adopts a laminated structure of "silica sand layer - activated carbon layer - modified nano-silver functional layer" to construct a multi-level gradient synergistic purification system of "coarse filtration - adsorption - antibacterial", so as to achieve targeted removal of multiple pollutants.

[0048] (1) The performance of nano-silver was significantly optimized and the antibacterial efficacy was greatly improved: By taking advantage of the cavity confinement effect of cyclodextrin and the synergistic effect of the steric hindrance and electrostatic repulsion of antimicrobial peptides, ultrafine nano-silver particles with a particle size of only 10 nm were successfully synthesized, which significantly enhanced the antibacterial activity; at the same time, the antimicrobial peptides can destroy the microbial membrane structure and accelerate the Ag ⁺ By entering the cell, the minimum inhibitory concentration (MIC) of nano-silver is reduced, broadening its antibacterial spectrum and resulting in better inactivation effects on bacteria, viruses, and other microorganisms.

[0049] (2) Multi-level gradient synergistic purification, comprehensively improving water purification efficiency: The silica sand layer intercepts large particulate pollutants (such as silt and rust) in the front, avoiding clogging of subsequent filter layers; the activated carbon layer efficiently adsorbs small molecule pollutants (such as residual chlorine, VOCs, benzene, aldehydes and other dissolved organic matter and pigments); the modified nano silver functional layer inactivates microorganisms while assisting in the removal of heavy metal ions, achieving synergistic and efficient removal of multiple types of pollutants such as suspended particles, colloids, organic matter, microorganisms, heavy metals, and residual chlorine, significantly improving the depth and purity of water purification.

[0050] (3) Improved filter layer stability and service life, enhanced application reliability The composite modification of antimicrobial peptide-cyclodextrin not only solves the problem of easy aggregation and easy failure of nano silver by suspended matter, but also enhances its dispersion stability in the filter cartridge system; and the hierarchical design of "coarse filtration-adsorption-antibacterial" reduces mutual interference and pollution of each functional layer, slows down the filter layer clogging speed, extends the overall service life of the filter cartridge, reduces the risk of secondary pollution, and improves the application reliability and practicality of the water purification device. Attached Figure Description

[0051] Figure 1 Here is a scanning electron microscope image of the modified silver nanoparticles from Example 1;

[0052] Figure 2 This is a scanning electron microscope image of the silver nanoparticles in Comparative Example 1.

[0053] Figure 3 This is a scanning electron microscope image of the silver nanoparticles in Comparative Example 2.

[0054] Figure 4 Here is a scanning electron microscope image of the modified silver nanoparticles from Example 2;

[0055] Figure 5 Here is a scanning electron microscope image of the modified silver nanoparticles from Example 3;

[0056] Figure 6 This is a schematic diagram of the filter element structure of the present invention;

[0057] Figure 7 This is a schematic cross-sectional view of the water purification device of the present invention.

[0058] The components are: 1. Silica sand layer; 2. Activated carbon adsorption layer; 3. Modified nano-silver functional layer; 4. Outer shell; 5. Inlet; 6. Outlet. Detailed Implementation

[0059] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0060] Throughout this specification, references to “an embodiment,” “an example,” or “an example” mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases “an embodiment,” “an example,” “an example,” or “an example” appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0061] Example 1

[0062] like Figures 6-7 The water purification device shown includes a food-grade PP plastic shell 4 with a diameter of 12cm and a total height of 25cm. The shell has a water inlet 5 and a water outlet 6. A filter element is encapsulated in the shell. The filter element includes a 10cm silica sand layer 1, a 12cm activated carbon adsorption layer 2, and a 3cm modified nano-silver functional layer 3 stacked along the water flow direction. The modified nano-silver functional layer includes nano-silver particles modified with antimicrobial peptide-cyclodextrin.

[0063] The specific preparation method of the filter element includes the following steps:

[0064] S1. Filling with silica sand layer: Select natural quartz sand (SiO2 content 99.5%) with a particle size of 0.8~1.0 mm, wash it with deionized water 3 times and dry it, then fill it to the bottom of the filter element (near the water inlet of the outer shell). The silica sand layer filling thickness is 10 cm and the filling density is 1.6 g / cm³.

[0065] S2. Fill the silica sand layer in S1 with an activated carbon adsorption layer: use high iodine value coconut shell activated carbon with an iodine value of 1100 mg / g and a particle size of 0.8~1.5 mm, fill it into the silica sand layer with a thickness of 12 cm and a filling density of 0.5 g / cm³. 3 ;

[0066] S3. Preparation of modified silver nanolayer functional layer:

[0067] Preparation of antimicrobial peptide-cyclodextrin solution: β-cyclodextrin was dissolved in hot water at 50℃ to prepare a saturated aqueous solution, which was then cooled to room temperature; a solution of silkworm antimicrobial peptide (CAS: 80451-05-4) was slowly added to the cyclodextrin solution, wherein the molar ratio of antimicrobial peptide to β-cyclodextrin was 1:10; the mixture was stirred, allowed to stand at 4℃ for 24 h, centrifuged at 10000 rpm for 10 min, and the supernatant was collected and freeze-dried to obtain the antimicrobial peptide-cyclodextrin inclusion complex; the antimicrobial peptide-cyclodextrin inclusion complex was dissolved in water to obtain a 5 mmol / L antimicrobial peptide-cyclodextrin solution;

[0068] Preparation of silver nanoparticles modified with antimicrobial peptide-cyclodextrin: In a 100 mL three-necked flask, 29 mL of deionized water, 20 mL of 5 mmol / L antimicrobial peptide-cyclodextrin solution, and 1 mL of 10 mmol / L silver nitrate solution were added and mixed thoroughly with a magnetic stirrer. The pH of the solution was then adjusted to 10 with 1 mmol / L sodium hydroxide solution, and the reaction was carried out at 60 °C for 2 h to prepare silver nanoparticles modified with antimicrobial peptide-cyclodextrin with a particle size of 10 nm.

[0069] Preparation of modified nano-silver functional layer: The antimicrobial peptide-cyclodextrin modified nano-silver particles are coated on the surface of cordierite, with the amount of nano-silver particles added being 0.002g / 1g cordierite, forming a modified nano-silver coating on its surface. The modified nano-silver functional layer formed by the cordierite loaded with the modified nano-silver coating is then placed on the activated carbon adsorption layer.

[0070] Example 2

[0071] A water purification device includes a food-grade PP plastic shell 4 with a diameter of 12cm and a total height of 25cm. The shell has a water inlet 5 and a water outlet 6. A filter element is encapsulated in the shell. The filter element includes a 10cm silica sand layer 1, a 10cm activated carbon adsorption layer 2, and a 2cm modified nano-silver functional layer 3 stacked along the water flow direction. The modified nano-silver functional layer includes nano-silver particles modified with antimicrobial peptide-cyclodextrin.

[0072] The specific preparation method of the filter element includes the following steps:

[0073] S1. Filling with silica sand layer: Select natural quartz sand (SiO2 content 99.5%) with a particle size of 0.8~1.0 mm, wash it with deionized water 3 times and dry it, then fill it to the bottom of the filter element (near the water inlet of the outer shell). The silica sand layer filling thickness is 10cm and the filling density is 1.6 g / cm³.

[0074] S2. Fill the silica sand layer in S1 with an activated carbon adsorption layer: use high iodine value coconut shell activated carbon with an iodine value of 1100 mg / g and a particle size of 0.8~1.5 mm, fill it into the silica sand layer with a filling thickness of 10 cm and a filling density of 0.5 g / cm³. 3 ;

[0075] S3. Preparation of modified silver nanolayer functional layer:

[0076] Preparation of antimicrobial peptide-cyclodextrin solution: α-cyclodextrin was dissolved in hot water at 50℃ to prepare a saturated aqueous solution, which was then cooled to room temperature; a solution of silkworm antimicrobial peptide (CAS: 80451-05-4) was slowly added to the cyclodextrin solution, wherein the molar ratio of antimicrobial peptide to α-cyclodextrin was 1:5; the mixture was stirred, allowed to stand at 4℃ for 24 h, centrifuged at 10000 rpm for 10 min, and the supernatant was collected and freeze-dried to obtain the antimicrobial peptide-cyclodextrin inclusion complex; the antimicrobial peptide-cyclodextrin inclusion complex was dissolved in water to obtain a 5 mmol / L antimicrobial peptide-cyclodextrin solution;

[0077] Preparation of silver nanoparticles modified with antimicrobial peptide-cyclodextrin: In a 100 mL three-necked flask, 29 mL of deionized water, 20 mL of the 5 mmol / L antimicrobial peptide-cyclodextrin solution from step S3, and 0.7 mL of the 10 mmol / L silver nitrate solution were added and mixed thoroughly with a magnetic stirrer. The pH of the solution was then adjusted to 12 with 1 mmol / L sodium hydroxide solution, and the reaction was carried out at 50 °C for 10 h to prepare silver nanoparticles modified with antimicrobial peptide-cyclodextrin with a particle size of 15 nm.

[0078] Preparation of modified nano-silver functional layer: The antimicrobial peptide-cyclodextrin modified nano-silver particles are coated on the surface of activated carbon. The amount of nano-silver particles added is 0.003g / 1g of activated carbon, forming a modified nano-silver coating on its surface, thus forming a modified nano-silver functional layer.

[0079] Example 3

[0080] A water purification device includes a food-grade PP plastic shell 4 with a diameter of 12cm and a total height of 25cm. The shell has a water inlet 5 and a water outlet 6. A filter element is encapsulated in the shell. The filter element includes a 10cm silica sand layer 1, a 16cm activated carbon adsorption layer 2, and a 5cm modified nano-silver functional layer 3 stacked along the water flow direction. The modified nano-silver functional layer includes nano-silver particles modified with antimicrobial peptide-cyclodextrin.

[0081] The specific preparation method of the filter element includes the following steps:

[0082] S1. Filling with silica sand layer: Select natural quartz sand (SiO2 content 99.5%) with a particle size of 0.8~1.0 mm, wash it with deionized water 3 times and dry it, then fill it to the bottom of the filter element (near the water inlet of the outer shell). The silica sand layer filling thickness is 10 cm and the filling density is 1.6 g / cm³.

[0083] S2. Fill the silica sand layer in S1 with an activated carbon adsorption layer: use high iodine value coconut shell activated carbon with an iodine value of 1100 mg / g and a particle size of 0.8~1.5 mm, fill it onto the silica sand layer with a thickness of 16 cm and a filling density of 0.5 g / cm³. 3 ;

[0084] S3. Preparation of modified silver nanolayer functional layer:

[0085] Preparation of antimicrobial peptide-cyclodextrin solution: γ-cyclodextrin was dissolved in hot water at 50℃ to prepare a saturated aqueous solution, which was then cooled to room temperature; antimicrobial peptide solution was slowly added to the cyclodextrin solution, wherein the molar ratio of antimicrobial peptide to γ-cyclodextrin was 1:20; the mixture was stirred, allowed to stand at 4℃ for 24 h, and centrifuged at 10000 rpm for 10 min. The supernatant was collected and freeze-dried to obtain the antimicrobial peptide-cyclodextrin inclusion complex. The antimicrobial peptide-cyclodextrin inclusion complex was dissolved in water to obtain a 5 mmol / L antimicrobial peptide-cyclodextrin solution.

[0086] Preparation of silver nanoparticles modified with antimicrobial peptide-cyclodextrin: In a 100 mL three-necked flask, 29 mL of deionized water, 20 mL of 5 mmol / L antimicrobial peptide-cyclodextrin solution, and 2 mL of 10 mmol / L silver nitrate solution were added and mixed thoroughly with a magnetic stirrer. The pH of the solution was then adjusted to 9 with 1 mmol / L sodium hydroxide solution, and the reaction was carried out at 80 °C for 1 h to prepare silver nanoparticles modified with antimicrobial peptide-cyclodextrin with a particle size of 20 nm.

[0087] Preparation of modified nano-silver functional layer: The antimicrobial peptide-cyclodextrin modified nano-silver particles are coated on the surface of cordierite, with the amount of nano-silver particles added being 0.005g / 1g, forming a modified nano-silver coating on its surface. The modified nano-silver functional layer formed by the cordierite loaded with the modified nano-silver coating is then placed on the activated carbon adsorption layer.

[0088] Example 4

[0089] The water purification device structure and filter element preparation method in Example 4 are basically the same as those in Example 1, with the only difference being: the thickness of the silica sand layer is 10 cm, the thickness of the activated carbon adsorption layer 2 is 5 cm, the modified nano-silver functional layer is 1 cm, and the amount of modified nano-silver particles is 0.0005 g / 1 g of activated carbon. The modified nano-silver particles are uniformly loaded on the surface of the activated carbon.

[0090] The remaining process steps and parameters are consistent with those in Example 1.

[0091] Example 5

[0092] The structure of the water purification device and the preparation method of the filter element in Example 5 are basically the same as those in Example 1. The only difference is that the thickness of the silica sand layer is 5cm, the thickness of the activated carbon adsorption layer 2 is 10cm, the modified nano-silver functional layer is 6cm, and the amount of modified nano-silver particles is 0.01g / 1g of activated carbon.

[0093] The remaining process steps and parameters are consistent with those in Example 1.

[0094] Comparative Example 1

[0095] The water purification device in Comparative Example 1 is basically the same in structure as that in Example 1, except that the silver nanoparticles in the filter cartridge are ordinary silver nanoparticles without antimicrobial peptide-cyclodextrin modification. The specific preparation method for this comparative example is as follows: 100 mL of an aqueous solution containing sodium citrate (SC) (5 mM) and tannic acid (TA) is prepared and heated for 15 minutes in a three-necked round-bottom flask with a heating mantle and vigorous stirring. A condenser is used to prevent solvent evaporation. After boiling begins, 1 mL of AgNO3 (25 mM) is injected into the solution, and the reaction is allowed to proceed for 5 minutes to obtain silver nanoparticles with a particle size of 10 nm.

[0096] Comparative Example 2

[0097] Comparative Example 2 and Example 1 have essentially the same water purification device structure, differing only in the preparation method of the silver nanoparticles in the filter cartridge. The specific preparation method for this comparative example is as follows: In a 100 mL three-necked flask, add 29 mL of deionized water, 20 mL of 5 mmol / L β-cyclodextrin solution, and 1 mL of 10 mmol / L silver nitrate solution, and mix thoroughly with a magnetic stirrer. Then, adjust the pH of the solution to 10 with 1 mmol / L sodium hydroxide solution, and react at 60 °C for 2 h to prepare silver nanoparticles with a particle size of 25 nm.

[0098] Scanning electron microscopy test:

[0099] From the appendix Figure 1 , 4 -5 and appendix Figures 2-3 The scanning electron microscope (SEM) images of the silver nanoparticles from Examples 1-3 and Comparative Examples 1-2 show that the average diameter of the silver nanoparticles in Example 1 is 10 nm, in Example 2 it is 15 nm, and in Example 3 it is 20 nm. The smallest diameter was observed in Example 1, indicating that the reaction conditions in Example 1 were optimal. In Comparative Example 1, sodium citrate and tannic acid were used as coating and reducing agents, respectively, and the synthesized silver nanoparticles had a diameter of 10 nm. However, the SEM images showed severe aggregation of the silver nanoparticles. This indicates that the cavity confinement effect of cyclodextrin and the synergistic effect of the steric hindrance and electrostatic repulsion of the antimicrobial peptides resulted in better dispersion of the silver nanoparticles, avoiding aggregation between particles.

[0100] The average diameter of the silver nanoparticles in Comparative Example 2 was 25 nm, indicating that using β-cyclodextrin as a coating agent alone resulted in larger-sized silver nanoparticles. This suggests that using antimicrobial peptide-modified cyclodextrin is more conducive to the synthesis of ultrafine silver nanoparticles.

[0101] Dispersibility and antibacterial efficacy tests:

[0102] The dispersibility and antibacterial effect of the silver nanoparticles prepared in Examples 1-5 and Comparative Examples 1-2 were tested. The specific test methods are as follows:

[0103] Dispersion test: Let the nano-silver particle dispersion stand for 48 hours and observe whether there is any sediment at the bottom. If there is sediment, the dispersion is NG; if there is no sediment, it is OK.

[0104] Determination of minimum inhibitory concentration (MIC)

[0105] (1) The MIC of antibacterial agent A against bacteria B was determined using the microdilution method. Preparation of bacterial suspension: Bacterial B was revived and enriched to OD0.05. 600mm =0.8, dilute the bacterial culture with double the concentration of liquid culture medium to 1x10. 6 CFU / mL concentration;

[0106] (2) Preparation of antimicrobial agent A: Antimicrobial agent A can be tested by a series of two-fold dilutions from 100 μM to 0.78125 μM.

[0107] (3) Setting up a 96-well plate: Under aseptic conditions, add the diluted drug sequentially to wells 2-9, 100 μL per well. Wells in column 10 are used as a growth control without antibiotics. Wells in column 11 are used as a control with 200 μL of a single concentration of culture medium (culture medium only). Three replicates are set for each concentration.

[0108] (4) Add 100 μL of diluted bacterial suspension to the wells containing the antibacterial agent. Add 200 μL of ddH2O around the outermost ring of the plate and place the inoculated 96-well plate at 37°C for 24 hours.

[0109] (3) First, the bacterial growth can be judged by observing whether the well is cloudy. A completely clear well indicates that the concentration of antibacterial agent in the well is sufficient to inhibit bacterial growth, and the corresponding concentration of antibacterial agent is the MIC value.

[0110] The test results are shown in Table 1.

[0111] Table 1

[0112]

[0113] Comparative analysis of the test results of Examples 1-3 and Comparative Examples 1-2 in Table 1 shows that the modified silver nanoparticle dispersions of Examples 1-3 and the silver nanoparticle dispersions of Comparative Example 2 did not show sedimentation after standing for 48 hours, indicating good dispersibility. This suggests that the cavity confinement effect of cyclodextrin and the synergistic effect of the steric hindrance and electrostatic repulsion of antimicrobial peptides help to synthesize ultrafine and dispersible silver nanoparticles.

[0114] After the dispersion of silver nanoparticles in Comparative Example 1 stood for 48 hours, obvious sedimentation occurred, indicating that the silver nanoparticles in Comparative Example 1 showed obvious aggregation, which affected the activity of the silver nanoparticles and slowed the release of silver ions from the silver nanoparticles, ultimately affecting their antibacterial ability. As a result, Comparative Example 1 had the highest inhibitory concentration of Escherichia coli and Staphylococcus aureus, while its antibacterial ability was the worst.

[0115] Examples 1-3 showed better antibacterial effects than Comparative Example 2. The use of antimicrobial peptide-cyclodextrin not only synthesized 10-20nm ultrafine silver nanoparticles, greatly improving the antibacterial properties of the silver nanoparticles, but also the antimicrobial peptide first disrupted the membrane structure, accelerated the entry of Ag⁺ into the cell, significantly reduced the MIC value of AgNPs, and enhanced the antibacterial activity and broad spectrum of silver nanoparticles.

[0116] In summary, this invention fully demonstrates that the laminated structure of the filter cartridge, consisting of a silica sand layer, an activated carbon layer, and a modified nano-silver functional layer, significantly improves the stability of the nano-silver particles in the filter cartridge structure compared to existing water purification filter cartridges. It also greatly enhances the antibacterial properties and antibacterial spectrum of the filter cartridge, thus laying a solid technical foundation for improving the water purification efficiency of water purification devices.

[0117] Water treatment effect test:

[0118] The water purification devices in Examples 1-5 and Comparative Example 1 were respectively connected to water (initial turbidity = 10 NTU, residual chlorine 0.3~0.6 mg / L, total bacterial count 50~200 CFU / mL, Pb 2+ The purification process was carried out at a flow rate of 100 L / h (0.001). The test results are shown in Table 2.

[0119] Table 2

[0120]

[0121] The comparative analysis of the test results of Examples 1-5 and Comparative Examples 1-2 in Table 2 shows that the water treatment effect of Examples 1-3 is better than that of Example 4. This is because the activated carbon layer in Example 4 is less, and the activated carbon layer efficiently adsorbs small molecule pollutants (such as residual chlorine, VOCs, benzene, aldehydes and other soluble organic matter and pigments), thus affecting the physical adsorption characteristics. In addition, the silver content in the nano silver layer in Example 4 is low, which leads to a reduction in the sterilization rate.

[0122] The water treatment effect of Examples 1-3 is better than that of Example 5 because Example 5 has too much activated carbon layer and too little silica sand layer, which makes it impossible for the silica sand layer to completely intercept large particulate pollutants (such as silt and rust), thus causing the activated carbon layer to become clogged and affecting the water purification efficiency of the water purification device.

[0123] Comparative Example 1 and Comparative Example 2 differ only in the nano-silver particles; everything else is the same as in Example 1. Therefore, their overall purification function is similar to that of Examples 1-3, except that their bactericidal ability is somewhat reduced.

[0124] In summary, the above experimental data and application effect analysis fully demonstrate that the water purification device equipped with an antimicrobial peptide-cyclodextrin modified nano-silver functional layer provided by the present invention has significantly improved water treatment performance compared with conventional water purification devices in the prior art.

[0125] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the nature and scope of the present invention. Various modifications made to the above embodiments by those skilled in the art after reading this specification are all within the scope of protection of the present invention.

Claims

1. A filter cartridge, characterized by, The filter core comprises a silica sand layer, an activated carbon adsorption layer and a modified nano-silver functional layer stacked along the direction of water flow; wherein the modified nano-silver functional layer comprises antibacterial peptide-cyclodextrin modified nano-silver particles.

2. A filter cartridge according to claim 1, wherein The material of the silica sand layer is at least one of natural quartz sand and modified silica sand; and / or, The material of the activated carbon adsorption layer is at least one of coconut shell activated carbon with iodine value ≥1000 mg / g and modified activated carbon; and / or, The antibacterial peptide-cyclodextrin modified nano-silver particles have a particle size of 10-20 nm.

3. The filter cartridge of claim 1 wherein, The thickness ratio of the silica sand layer, the activated carbon adsorption layer and the modified nano-silver functional layer is 1:(1-1.6):(0.2-0.5), and the nano-silver particles account for 0.2-0.5 wt% of the modified nano-silver functional layer.

4. A method of making a filter cartridge according to any one of claims 1-3, characterized in that, The method comprises the following steps: S1. Filling the silica sand layer; S2. Filling the activated carbon adsorption layer on the silica sand layer of S1; S3. Preparing the modified nano-silver functional layer: Antibacterial peptide-cyclodextrin solution preparation: adding antibacterial peptide solution to cyclodextrin solution, stirring, standing, centrifuging to obtain supernatant, and freeze-drying to obtain antibacterial peptide-cyclodextrin inclusion compound, which is dissolved in water to obtain antibacterial peptide-cyclodextrin solution; Antibacterial peptide-cyclodextrin modified nano-silver particle preparation: adding silver nitrate solution to the antibacterial peptide-cyclodextrin solution at 50-80℃, adjusting the pH value to 9-12, and stirring to obtain antibacterial peptide-cyclodextrin modified nano-silver particles; Modified nano-silver functional layer preparation: coating the antibacterial peptide-cyclodextrin modified nano-silver particles on the surface of a carrier to form a modified nano-silver coating layer, and setting the modified nano-silver functional layer formed by the carrier loaded with the modified nano-silver coating layer on the activated carbon adsorption layer.

5. A method of making a filter cartridge according to claim 4 wherein, In S3, the molar ratio of antibacterial peptide-cyclodextrin inclusion compound to silver nitrate is (5-15):

1.

6. The method of claim 4, wherein the filter element is formed by winding the filter material around the filter element core. In S3, the molar ratio of antibacterial peptide to cyclodextrin is 1:(5-20).

7. The method of claim 4, wherein the filter element is formed by a process comprising: In S3, the pH value is adjusted to 9-12 by using sodium hydroxide solution.

8. The method of claim 4, wherein the filter element is formed by a process comprising: The carrier is an activated carbon adsorption layer or a porous ceramic carrier.

9. The method for preparing a filter core according to claim 4, wherein the reaction time of antibacterial peptide-cyclodextrin inclusion compound and silver nitrate is 1-10 h.

10. A water purifying apparatus characterized by comprising: The filter core comprises the filter core according to any one of claims 1-3, or the filter core prepared by the method for preparing a filter core according to any one of claims 4-9.

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