Cationic tannin and prolamin composite nano system as well as preparation method and application thereof

Abstract

The invention relates to a cationic tannin and prolamin composite nano system and a preparation method and application thereof.The cationic tannin and prolamin composite nano system is prepared through the steps that cationic tannin and prolamin are dissolved in an alcoholic solution through an anti-solvent dispersion method, then the alcoholic solution is dropwise added and dispersed in water, and the cationic tannin and prolamin composite nano system is obtained. Nano-particles are formed through self-assembly under the interaction of non-covalent acting force between cationic tannin and prolamin in an aqueous solution, and the composite nano-system is applied to water treatment. Compared with the prior art, the water treatment agent is good in storage stability and has excellent performance of removing antibiotic pollution in a water body.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment materials, and relates to a composite nano-system of cationic tannin and zein, a preparation method thereof, and an application thereof. Background Art

[0002] With the wide use of antibiotics in fields such as medical treatment and animal husbandry, a large number of antibiotics and their metabolites enter the environment through different channels, posing a threat to the ecosystem and human health. Every year globally, a significant amount of antibiotics ultimately enter the environment through emissions and other means, and a considerable part of them flows into water bodies, leading to the generation and spread of drug-resistant bacteria and having a non-negligible impact on aquatic organisms. Facing this challenge, scientific researchers have been searching for efficient, economical, and environmentally friendly methods for removing antibiotics. Traditional treatment technologies, such as activated carbon adsorption, advanced oxidation, and biodegradation, although can remove antibiotics in water to a certain extent, all have their own limitations. Activated carbon has strong adsorption ability, but requires physical or chemical activation and has a high cost; advanced oxidation technology can effectively degrade antibiotics in wastewater, but still needs to improve its adaptability and practicality; while the biodegradation method is often restricted by the different characteristics of antibiotics themselves and the adsorption phenomenon in soil, and it is difficult to achieve an ideal treatment effect.

[0003] In the process of exploring new water treatment technologies, natural materials have shown good application potential due to their unique structures and properties. Zein is the main by-product of food processing and the bioethanol industry, is inexpensive and easily available, and has been proven to have excellent biocompatibility and biodegradability. Due to the highly hydrophobic property of zein, it has good self-assembly characteristics in aqueous solutions. Coupled with the fact that it is composed of various different amino acids and contains multiple free functional groups such as amino, hydroxyl, and carboxyl groups, it can interact with specific pollutants through multiple forces, making it a promising candidate in the field of wastewater treatment. Currently, zein has been designed into various forms such as nanoparticles, nanofibers, micro / nanofilms, etc. to effectively remove pollutants such as heavy metals, organic dyes, and engine oil in sewage. In existing reports, there is still little research on the removal of antibiotic pollutants in water by zein.

[0004] Tannins are secondary metabolites of plant polyphenols, mainly present in the leaves, roots, bark and fruits of plants. They are the most abundant compounds extracted from plants after cellulose, hemicellulose and lignin. The structure of tannins contains a large number of phenolic hydroxyl groups, which have hydrophilicity, metal complexation ability, cation exchange ability, etc. They are commonly used adsorbents and flocculants in the field of water treatment. The abundant hydroxyl groups on tannins can interact with antibiotic molecules through various mechanisms to effectively remove antibiotics in water. However, the water-soluble characteristics of tannins limit their large-scale application as adsorbents in actual water treatment. To overcome these limitations in the application of tannins, researchers have tried various methods such as loading and in-situ modification. The paper (Chem Eng J, 2011, 168(3):1241-1247) gelated tannin extracts from four different natural plant sources with formaldehyde and acetaldehyde, and investigated the removal effects of different combinations on Zn 2+ , methylene blue and cetyltrimethylammonium bromide in aqueous solution. The results showed that according to the general adsorption behavior of Langmuir, these tannin gels had good effects in removing these pollutants. However, for the modified tannin materials in this report, on the one hand, highly toxic chemical reagents such as formaldehyde and acetaldehyde were introduced during the modification process, which may introduce secondary pollution during the water treatment process. On the other hand, the modified tannin materials in this report exist in the state of solid foam when used as water treatment agents, and their removal efficiency is limited compared with nanomaterials.

[0005] Therefore, it is very necessary to further develop new water treatment materials that can efficiently remove antibiotics in water and are environmentally friendly.

[0006] Patent CN103734742A discloses a polyphenol-hordein nanoparticle and its preparation method. The preparation method is to first prepare a hordein solution and a polyphenol solution, then mix the hordein solution and the polyphenol solution, centrifuge the obtained mixture, and drop the obtained supernatant into distilled water drop by drop under vortex mixing conditions. The obtained dispersion is freeze-dried to obtain polyphenol-hordein nanoparticles. However, in this patent, the mixture of hordein and polyphenol is centrifuged at a speed of 3000 rpm for 13 min, and then the supernatant is taken and dropped into distilled water to obtain a dispersion. This centrifugation operation step will cause a large loss of hordein and polyphenol substances, resulting in waste of raw materials and low yield. In addition, the stirring speed when the supernatant is dropped into distilled water after centrifugation is not specified in this patent, and this parameter is crucial for the formation of the nano-system and the control of parameters such as the particle size of the formed nanoparticles.

[0007] Patent CN115651276A discloses a chitosan composite film containing protein nanoparticles and its preparation method and application, in which protein nanoparticles are formed by zein and tannic acid through an anti-solvent precipitation method. However, the steps for preparing nanoparticles by the anti-solvent method in this patent are as follows: adding 2.5 times the volume of water to a 70% (v / v) ethanol solution of zein-tannic acid. The addition of such a large amount of anti-solvent water will cause the zein, which is insoluble in water in the original ethanol solution, to rapidly aggregate in large quantities, forming insoluble particles with a relatively large particle size. Therefore, the particle size formed in this patent only reaches a particle size of less than 1 μm, and it is difficult to form nanoparticles. Such particles with a relatively large particle size often have defects such as poor stability and easy aggregation and precipitation, which are not conducive to preparation and storage, and at the same time, it is very difficult to have the nano-effects possessed by nanoparticles at the nanoscale.

[0008] Patent CN114015094A discloses a high-strength gliadin chitosan composite film and its preparation method, in which the preparation of gliadin includes the following steps: grinding barley seeds into powder, mixing with n-hexane and stirring to obtain a homogeneous slurry, centrifuging to obtain a precipitate and washing it successively with ultrapure water and sodium chloride solution; mixing the precipitate with barley flour in an ethanol solution and stirring evenly; centrifuging to collect the supernatant and removing ethanol by rotary evaporation; obtaining a freeze-dried powder after freeze-drying. However, the alcohol extraction step in this patent is at 55 °C and extracting for 2 h in a 75% (v / v) ethanol aqueous solution. It was found in the research of the paper (Cereal Chemistry. Volume 87, Issue 6. 2010. PP 597-606) that the extraction rate of barley protein in the 75% (v / v) alcohol solution in this patent is relatively low.

[0009] Patent CN118005712A discloses a method and reagent composition for extracting proteins from distiller's grains of Chinese liquor by reverse micelle extraction method, in which proteins in the distiller's grains are extracted by an alcohol-alkali method to obtain a supernatant; the supernatant is freeze-dried, defatted, and dried to obtain distiller's grain gliadin powder. On this basis, a reverse micelle method or a defatting-reverse micelle method is added to form an alcohol-alkali method-reverse micelle method and an alcohol-alkali method-defatting-reverse micelle method. However, these two combined methods in this patent add multiple steps of operation on the basis of the alcohol-alkali method, introducing a variety of chemical reagents such as cationic surfactant DTAB and guanidine hydrochloride, as well as a large amount of organic solvents such as n-octane and n-hexanol. On the one hand, it increases the extraction cost and extraction difficulty of distiller's grain gliadin, which is contrary to the purpose of the re-effective utilization of distiller's grains, a by-product of grain processing; on the other hand, when used as a water treatment agent, it may introduce secondary pollution into the water body to be treated; in addition, the protein extraction yield of the original alcohol-alkali method in this patent is 7.02%, while in contrast, the protein yields of the alcohol-alkali method-reverse micelle method and the alcohol-alkali method-defatting-reverse micelle method are 2.36% and 2.14% respectively, which are significantly reduced and not conducive to industrialization. Summary of the Invention

[0010] The object of the present invention is to overcome at least one defect of the above-mentioned existing technologies, and to provide a composite nano-system of cationic tannin and prolamine, its preparation method and application. The storage stability of the present invention is good, and it has excellent performance in removing antibiotic pollution in water bodies.

[0011] The object of the present invention can be achieved by the following technical solutions:

[0012] One of the technical solutions of the present invention is to provide a composite nano-system of cationic tannin and prolamine. This composite nano-system is formed by dissolving cationic tannin and prolamine in an alcohol solution by the anti-solvent dispersion method, and then dropping and dispersing the alcohol solution in water. In the aqueous solution, nano-particles are self-assembled by non-covalent interactions such as hydrogen bond force and hydrophobic force between cationic tannin and prolamine. The composite nano-system is applied to water treatment.

[0013] The cationic tannin is a water-soluble cationic tannin obtained by cationization modification of plant tannin.

[0014] Furthermore, the mass ratio of the cationic tannin to the prolamine is 1:(5 - 25).

[0015] One of the technical solutions of the present invention is to provide a preparation method of the above-mentioned composite nano-system of cationic tannin and prolamine. This method includes the following steps:

[0016] S1. Extract prolamine from grain powder or grain processing by-products;

[0017] S2. Add cationic tannin and prolamine into an alcohol solution, and ultrasonically dissolve and mix evenly;

[0018] S3. Drop the alcohol solution into water, continuously stir and disperse evenly to obtain a composite nano-system of cationic tannin and prolamine.

[0019] As a preferred technical solution, in step S1, the grain powder is selected from corn flour, barley flour, wheat flour or sorghum flour, and the grain processing by-product is distiller's grains.

[0020] Furthermore, in step S1, prolamine is extracted from the grain powder by first degreasing and then extracting with alcohol. The first degreasing and then extracting with alcohol includes the following steps:

[0021] Add the grain powder into a degreasing agent, degrease, centrifuge to collect the precipitate, and dry to obtain degreased grain powder;

[0022] Add the degreased grain powder into a salt solution and water successively, extract, and centrifuge to remove the supernatant after each extraction;

[0023] Add the centrifuged precipitate to an alcohol solution, mix, and centrifuge to collect the supernatant;

[0024] Concentrate the supernatant by rotary evaporation, let it stand and refrigerate, centrifuge to collect the precipitate, and freeze-dry to obtain the alcohol-soluble protein;

[0025] The degreasing agent is selected from one or more of n-hexane, diethyl ether, petroleum ether, and chloroform-methanol. The mass ratio of the grain powder to the degreasing agent is 1:(2 - 8);

[0026] The temperature of degreasing is 10 - 40°C, the stirring speed is 100 - 500 rpm, and the time is 0.5 - 4 h;

[0027] The solute of the salt solution is selected from one or more of sodium chloride (NaCl), potassium chloride (KCl), magnesium chloride (MgCl2), and sodium sulfate (Na2SO4). The solvent is water, and the molar concentration is 0.5 - 1.5 mol / L. The mass / volume ratio of the degreased grain powder to the salt solution is 1 g:(2 - 8 mL);

[0028] The temperature of extraction is 25 - 65°C, the stirring speed is 100 - 500 rpm, and the time is 0.5 - 4 h;

[0029] The solute of the alcohol solution is selected from one or more of ethanol, n-propanol, and isopropanol. The solvent is water, and the volume fraction is 40 - 90%. The mass / volume ratio of the precipitate to the alcohol solution is 1 g:(2 - 8 mL);

[0030] The temperature of mixing is 25 - 65°C, the stirring speed is 100 - 500 rpm, and the time is 0.5 - 4 h;

[0031] Concentrate the volume of the supernatant by rotary evaporation to 1 / 8 - 1 / 2 of the original volume;

[0032] The temperature of refrigeration is 0 - 10°C, and the time is 6 - 24 h.

[0033] As a preferred technical solution, the rotation speed of centrifugation after degreasing is 1000 - 10000 rpm, the temperature is 0 - 40°C, and the time is 5 - 20 min;

[0034] The temperature of drying is 10 - 40°C, and the time is 5 - 24 h;

[0035] The rotation speed of centrifugation after extraction is 1000 - 10000 rpm, the temperature is 0 - 40°C, and the time is 5 - 20 min;

[0036] The rotation speed of centrifugation after mixing is 1000 - 10000 rpm, the temperature is 0 - 40°C, and the time is 5 - 20 min;

[0037] The temperature of the rotary evaporation and concentration is 50 - 60 °C, the vacuum degree is 0.01 - 0.05 MPa, the rotation speed is 50 - 100 rpm, and the time is 20 - 120 min.

[0038] The rotation speed of the centrifugation after refrigeration is 5000 - 12000 rpm, the temperature is 0 - 10 °C, and the time is 5 - 30 min.

[0039] The temperature of the freeze-drying is -55 - -40 °C, and the time is 8 - 24 h.

[0040] Furthermore, in step S1, the prolamine is extracted from the food processing by-products by the alcohol-alkali method, and the alcohol-alkali method includes the following steps:

[0041] Add the food processing by-products into an alcohol solution containing a protein antioxidant protector and an alkali, extract, and centrifuge to collect the supernatant.

[0042] Dilute the supernatant, let it stand and refrigerate, centrifuge to collect the precipitate, wash it, and freeze-dry it.

[0043] Add the freeze-dried powder into a degreasing agent, degrease, centrifuge to collect the precipitate, and dry it to obtain the prolamine.

[0044] The protein antioxidant protector is selected from one or more of sodium metabisulfite and sodium bisulfite, the mass concentration of the protein antioxidant protector is 0.5 - 8 g / L, the alkali is selected from one or more of sodium hydroxide (NaOH) and potassium hydroxide (KOH), the mass concentration of the alkali is 1.5 - 5.5 g / L, the solute of the alcohol solution is selected from one or more of ethanol, n-propanol, and isopropanol, the solvent is water, and the volume fraction is 60 - 90%, and the mass / volume ratio of the food processing by-products to the alcohol solution is 1 g:(5 - 15 mL).

[0045] The temperature of the extraction is 50 - 80 °C, the stirring rotation speed is 100 - 500 rpm, and the time is 0.5 - 4 h.

[0046] Dilute the volume fraction of the alcohol solution in the supernatant to 30 - 60%.

[0047] The temperature of the refrigeration is -30 - -10 °C, and the time is 6 - 24 h.

[0048] The degreasing agent is selected from one or more of n-hexane, ether, petroleum ether, and chloroform-methanol, and the mass ratio of the powder to the degreasing agent is 1:(2 - 8).

[0049] The temperature of the degreasing is 10 - 40 °C, the stirring rotation speed is 100 - 500 rpm, and the time is 0.5 - 4 h.

[0050] As a preferred technical solution, the rotation speed of centrifugation after extraction is 1000 - 10000 rpm, the temperature is 0 - 40 °C, the time is 5 - 20 min, and the number of times is 2 - 4 times;

[0051] The rotation speed of centrifugation after refrigeration is 5000 - 12000 rpm, the temperature is 0 - 10 °C, and the time is 5 - 30 min.

[0052] The reagent for washing is water.

[0053] The temperature for washing is 10 - 40 °C, and the number of times is 2 - 4 times.

[0054] The temperature for freeze - drying is - 55 - - 40 °C, and the time is 8 - 24 h.

[0055] The rotation speed of centrifugation after degreasing is 1000 - 10000 rpm, the temperature is 0 - 40 °C, and the time is 5 - 20 min.

[0056] The temperature for drying is 10 - 40 °C, and the time is 5 - 24 h.

[0057] Further, in step S1, prolamin is extracted from food processing by - products by the acetic acid method, and the acetic acid method includes the following steps:

[0058] Add food processing by - products into the protein antioxidant protection agent solution, soak, and filter to remove the filtrate.

[0059] Add the filtered cake into acetic acid, extract, and centrifuge to collect the supernatant.

[0060] Use an alkali solution to adjust the pH value of the supernatant to precipitate the protein, let it stand and refrigerate, centrifuge to collect the precipitate, wash it with water, and then freeze - dry.

[0061] Add the freeze - dried powder into the degreasing agent, degrease, centrifuge to collect the precipitate, and dry to obtain prolamin.

[0062] The solute of the protein antioxidant protection agent solution is selected from one or more of sodium metabisulfite and sodium bisulfite, the solvent is water, and the mass concentration is 0.5 - 8 g / L. The volume ratio of the food processing by - products to the protein antioxidant protection agent solution is 1:(2 - 6).

[0063] The temperature for soaking is 10 - 40 °C, and the time is 8 - 24 h.

[0064] The mass / volume ratio of the cake to acetic acid is 1 g:(2 - 8 mL).

[0065] The temperature for extraction is 10 - 40 °C, the stirring rotation speed is 100 - 500 rpm, and the time is 0.5 - 4 h.

[0066] The alkaline solution is a saturated solution, and the solute of the alkaline solution is selected from one or more of sodium hydroxide and potassium hydroxide, and the solvent is water.

[0067] Adjust the pH value of the supernatant to 4 - 6, and the temperature for adjustment is 1 - 10°C.

[0068] The temperature for refrigeration is 0 - 10°C, and the time is 6 - 24 h.

[0069] The degreasing agent is selected from one or more of n - hexane, ether, petroleum ether, and chloroform - methanol, and the mass ratio of the powder to the degreasing agent is 1:(2 - 8).

[0070] The temperature for degreasing is 10 - 40°C, the stirring speed is 100 - 500 rpm, and the time is 0.5 - 4 h.

[0071] As a preferred technical solution, the temperature for filtration after soaking is 10 - 40°C.

[0072] The rotation speed for centrifugation after extraction is 1000 - 10000 rpm, the temperature is 0 - 40°C, the time is 5 - 20 min, and the number of times is 2 - 4 times.

[0073] The rotation speed for centrifugation after refrigeration is 5000 - 12000 rpm, the temperature is 0 - 10°C, and the time is 5 - 30 min.

[0074] The temperature for washing is 10 - 40°C, and the number of times is 2 - 4 times.

[0075] The temperature for freeze - drying is - 55 - - 40°C, and the time is 8 - 24 h.

[0076] The rotation speed for centrifugation after degreasing is 1000 - 10000 rpm, the temperature is 0 - 40°C, and the time is 5 - 20 min.

[0077] The temperature for drying is 10 - 40°C, and the time is 5 - 24 h.

[0078] Furthermore, in step S2, the solute of the alcohol solution is selected from one or more of ethanol, n - propanol, and isopropanol, the solvent is water, the volume fraction is 50 - 90%, and the mass / volume ratio of the alcohol - soluble protein to the alcohol solution is (5 - 15 g):1 L.

[0079] The frequency of ultrasonic wave is 16 - 24 kHz, the temperature is 10 - 40°C, and the time is 5 - 30 min.

[0080] Furthermore, in step S3, the dropping speed of the alcohol solution is 0.3 - 1.1 mL / min, and the volume ratio of the alcohol solution to water is 1:(3 - 7).

[0081] As a preferred technical solution, the dropping rate of the alcohol solution in step S3 is 0.3 mL / min, 0.5 mL / min, 0.7 mL / min, 0.9 mL / min or 1.1 mL / min.

[0082] Furthermore, in step S3, the stirring speed is 400 - 1300 rpm, the temperature is 10 - 40 °C, and the time is 10 - 60 min.

[0083] One of the technical solutions of the present invention is to provide an application of the above-mentioned cationic tannin and zein composite nano - system, and the composite nano - system removes antibiotics in water with a pH value of 3 - 11.

[0084] Compared with the prior art, the present invention has the following beneficial effects:

[0085] (1) Aiming at the limitations that water - soluble cationic tannins still face in water treatment applications, such as high water solubility, difficulty in large - scale application and difficult recovery, etc., without changing the structure of cationic tannins themselves, the present invention uses the anti - solvent dispersion method to load cationic tannins on zein nanoparticles through non - covalent interactions, forming a composite nano - system, which has a solidification and loading effect on cationic tannins, solves the problem of its high water solubility, and while maximizing the retention of the water treatment ability of cationic tannins, combines the nano - effects such as high dispersibility, high specific surface area and high adsorption efficiency of nanoparticles itself to prepare an efficient sewage treatment reagent;

[0086] (2) The cationic tannin - zein composite nano - system of the present invention has excellent storage stability, is suitable for industrial production and use; and for the currently much - concerned antibiotic pollution, the cationic tannin - zein composite nano - system can effectively remove antibiotic pollution in water and achieve good removal effects;

[0087] (3) The anti - solvent dispersion method adopted by the cationic tannin - zein composite nano - system of the present invention has a simple and mild preparation method, is simple and easy to operate; and both tannins and zein as raw materials in the composite nano - system are derived from plants, are natural materials, have excellent biocompatibility and degradability, and are widely and richly sourced, and can be extracted from grain powders and food processing by - products, are cheap and easily available; therefore, the cationic tannin - zein composite nano - system of the present invention has a low preparation cost, is safe and green, will not introduce secondary pollution when used as a water treatment agent, especially when treating natural water bodies, and has strong operability and is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 It is a process flow diagram of the preparation method of the cationic tannin and zein composite nano - system in Examples 1 to 5 of the present invention;

[0089] Figure 2 These are the macroscopic morphology diagrams of the nano - systems in Examples 1 - 5 and Comparative Example 1 of the present invention;

[0090] Figure 3 These are the scanning electron microscopy (SEM) micro - morphology diagrams of zein nanoparticles at a large scale in Comparative Example 1 of the present invention;

[0091] Figure 4 These are the SEM micro - morphology diagrams of zein nanoparticles at a small scale in Comparative Example 1 of the present invention;

[0092] Figure 5 These are the SEM micro - morphology diagrams of the composite nanoparticles of cationic tannin and zein at a large scale in Example 5 of the present invention;

[0093] Figure 6 These are the SEM micro - morphology diagrams of the composite nanoparticles of cationic tannin and zein at a small scale in Example 5 of the present invention;

[0094] Figure 7 These are the Fourier transform infrared (FTIR) spectra of the composite nanoparticles of cationic tannin and zein in Example 5 of the present invention, and the pure products of zein and cationic tannin in Comparative Examples 2 and 3;

[0095] Figure 8 These are the differential scanning calorimetry (DSC) spectra of the composite nanoparticles of cationic tannin and zein in Example 5 of the present invention, and the pure products of zein and cationic tannin in Comparative Examples 2 and 3;

[0096] Figure 9 These are the X - ray diffraction (XRD) spectra of the composite nanoparticles of cationic tannin and zein in Example 5 of the present invention, and the pure products of zein and cationic tannin in Comparative Examples 2 and 3;

[0097] Figure 10 These are the diagrams of the particle size change of the zein nano - system after long - term storage in Comparative Example 1 of the present invention;

[0098] Figure 11 These are the diagrams of the particle size change of the composite nano - system of cationic tannin and zein after long - term storage in Example 5 of the present invention;

[0099] Figure 12 These are the diagrams of the change in the polydispersity index (PDI) of the zein nano - system after long - term storage in Comparative Example 1 of the present invention;

[0100] Figure 13 These are the diagrams of the change in the PDI of the composite nano - system of cationic tannin and zein after long - term storage in Example 5 of the present invention;

[0101] Figure 14 It is the Zeta potential change diagram of the zein nano-system in Comparative Example 1 of the present invention after long-term storage;

[0102] Figure 15 It is the Zeta potential change diagram of the composite nano-system of cationic tannin and zein in Example 5 of the present invention after long-term storage;

[0103] Figure 16 It is the standard curve diagram of ultraviolet absorbance - cefotaxime sodium concentration of the composite nano-system of cationic tannin and zein in Example 5 of the present invention;

[0104] Figure 17 It is the comparison diagram of the antibiotic removal rates of the nano-systems in Example 5 and Comparative Example 1 of the present invention;

[0105] Figure 18 It is the antibiotic removal rate diagram of the composite nano-system of cationic tannin and zein in Example 5 of the present invention at different pH values. Detailed implementation manners

[0106] The present invention will be described in detail below in conjunction with specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation procedures are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0107] Unless otherwise specified, the equipment used in the following embodiments is all conventional equipment in the art; unless otherwise specified, the reagents used are all commercially available products or prepared by conventional methods in the art. Those not described in detail in the following embodiments can be achieved by conventional experimental means in the art.

[0108] Example 1:

[0109] A composite nano-system of cationic tannin and zein, as Figure 1 shown, is composed of cationic tannin (Cationic Tannin, CAT, the CATf-1 type water-soluble cationic tannin of Solenis (Shanghai) Chemical Co., Ltd. obtained by cationic modification of plant tannin) and zein. Through the anti-solvent dispersion method, it is first dissolved in an alcohol solution, and then the alcohol solution is dropped and dispersed in water. In the aqueous solution, between cationic tannin and zein, based on the hydrogen bond forces generated between active groups such as hydroxyl, amino, and carboxyl groups, and non-covalent forces such as hydrophobic forces, they interact and self-assemble to form cationic tannin-zein (Cationic Tannin-Zein, CAT-Zein) composite nanoparticles. The composite nano-system is applied to water treatment.

[0110] The preparation method of the above-mentioned cationic tannin and zein composite nano-system is as follows:

[0111] S1. Extract zein from corn flour by first degreasing and then extracting with alcohol. Add corn flour to n-hexane at a solid-liquid ratio of 1:6 (w / w), stir at 200 rpm for 2 h at room temperature of 25 °C for degreasing, centrifuge at 4000 rpm for 10 min at room temperature of 25 °C to collect the precipitate, and dry it overnight for 12 h in a fume hood at room temperature of 25 °C to obtain defatted corn flour;

[0112] Add the defatted corn flour to 1 mol / L sodium chloride (NaCl) aqueous solution and deionized water successively at a solid-liquid ratio of 1:6 (w / v, g:mL), stir at 200 rpm for 1 h at 55 °C for each extraction, and centrifuge at 4000 rpm for 10 min at room temperature of 25 °C to remove the supernatant after each extraction;

[0113] Add the centrifuged precipitate to 55% (v / v) isopropanol aqueous solution at a solid-liquid ratio of 1:6 (w / v, g:mL), stir and mix at 200 rpm for 1 h at 55 °C, and centrifuge at 4000 rpm for 10 min at room temperature of 25 °C to collect the supernatant;

[0114] Concentrate the volume of the supernatant by rotary evaporation at 55 °C, a vacuum of 0.02 MPa, and a rotation speed of 80 rpm for 60 min to 1 / 6 of the original volume, place it in a refrigerator at 4 °C and let it stand overnight for 12 h, centrifuge at 10000 rpm for 20 min at 4 °C to collect the precipitate, and freeze-dry it overnight for 12 h at -50 °C to obtain zein powder;

[0115] S2. Add 2 mg of cationic tannin and 50 mg of zein to 5 mL of 70% (v / v) ethanol aqueous solution at the same time. The mass ratio of cationic tannin to zein is 1:25, and the mass / volume ratio of zein to ethanol aqueous solution is 10 g:1 L. Ultrasonically dissolve and mix evenly at 20 kHz for 20 min at room temperature of 25 °C;

[0116] S3. Use a peristaltic pump to drop the ethanol aqueous solution into 25 mL of pure water at a speed of 0.9 mL / min. The volume ratio of the ethanol aqueous solution to water is 1:5. Continuously stir at 750 rpm for 30 min at room temperature of 25 °C using a magnetic stirrer to obtain a dispersion of CAT-Zein composite nanoparticles.

[0117] Example 2:

[0118] A cationic tannin and zein composite nano - system and its preparation method are basically the same as those in Example 1, except that in step S2, 2.5 mg of cationic tannin and 50 mg of zein are simultaneously added to 5 mL of 70% (v / v) ethanol aqueous solution, and the mass ratio of cationic tannin to zein is 1:20.

[0119] Example 3:

[0120] A cationic tannin and zein composite nano - system and its preparation method are basically the same as those in Example 1, except that in step S2, 3.3 mg of cationic tannin and 50 mg of zein are simultaneously added to 5 mL of 70% (v / v) ethanol aqueous solution, and the mass ratio of cationic tannin to zein is 1:15.

[0121] Example 4:

[0122] A cationic tannin and zein composite nano - system and its preparation method are basically the same as those in Example 1, except that in step S2, 5 mg of cationic tannin and 50 mg of zein are simultaneously added to 5 mL of 70% (v / v) ethanol aqueous solution, and the mass ratio of cationic tannin to zein is 1:10.

[0123] Example 5:

[0124] A cationic tannin and zein composite nano - system and its preparation method are basically the same as those in Example 1, except that in step S2, 10 mg of cationic tannin and 50 mg of zein are simultaneously added to 5 mL of 70% (v / v) ethanol aqueous solution, and the mass ratio of cationic tannin to zein is 1:5.

[0125] Example 6:

[0126] A cationic tannin and zein composite nano - system and its preparation method are basically the same as those in Example 5, except that corn flour and zein are correspondingly replaced with barley flour and hordein.

[0127] Example 7:

[0128] A cationic tannin and zein composite nano - system and its preparation method are basically the same as those in Example 5, except that corn flour and zein are replaced with distillers' grains and distillers' - grain zein correspondingly. In step S1, distillers' - grain zein is extracted from distillers' grains by the alcohol - alkali method. The distillers' grains are added to an aqueous ethanol solution of 70% (v / v) containing 5 g / L sodium metabisulfite and 3.5 g / L sodium hydroxide (NaOH) at a solid - liquid ratio of 1:10 (w / v, g:mL), and stirred at 70 °C at a speed of 200 rpm for 1 h. Then, it is centrifuged at 4000 rpm for 10 min at 25 °C to collect the supernatant, and this is repeated 3 times.

[0129] The volume fraction of ethanol in the supernatant is diluted to 40%, placed in a - 20 °C refrigerator and refrigerated overnight for 12 h, then centrifuged at 10000 rpm for 20 min at 4 °C to collect the precipitate, washed 3 times with distilled water at 25 °C, and freeze - dried overnight for 12 h at - 50 °C.

[0130] The freeze - dried powder is added to n - hexane at a solid - liquid ratio of 1:6 (w / w), stirred at 200 rpm for 2 h at 25 °C for defatting, centrifuged at 4000 rpm for 10 min at 25 °C to collect the precipitate, and air - dried overnight for 12 h in a fume hood at 25 °C to obtain distillers' - grain zein.

[0131] Example 8:

[0132] A cationic tannin and zein composite nano - system and its preparation method are basically the same as those in Example 5, except that corn flour and zein are replaced with distillers' grains and distillers' - grain zein correspondingly. In step S1, distillers' - grain zein is extracted from distillers' grains by the acetic acid method. The distillers' grains are added to an aqueous solution of 5 g / L sodium metabisulfite at a solid - liquid ratio of 1:4 (v / v), soaked at 25 °C for 16 h, and filtered at 25 °C to remove the filtrate.

[0133] The filtered cake is added to acetic acid at a solid - liquid ratio of 1:5 (w / v, g:mL), stirred at 200 rpm for 1 h at 25 °C, centrifuged at 4000 rpm for 10 min at 25 °C to collect the supernatant, and this is repeated 3 times.

[0134] Under the condition of an ice - bath at 4 °C, the pH value of the supernatant is adjusted to 5.0 with a saturated sodium hydroxide aqueous solution to precipitate the protein, placed in a 4 °C refrigerator and refrigerated overnight for 12 h, centrifuged at 10000 rpm for 20 min at 4 °C to collect the precipitate, washed 3 times with distilled water at 25 °C, and freeze - dried overnight for 12 h at - 50 °C.

[0135] The freeze-dried powder was added to n-hexane at a solid-liquid ratio of 1:6 (w / w), stirred at 200 rpm for 2 h at 25 °C for defatting, centrifuged at 4000 rpm for 10 min at 25 °C to collect the precipitate, and air-dried overnight for 12 h in a fume hood at 25 °C to obtain distillers' prolamine.

[0136] Comparative Example 1:

[0137] An alcohol-soluble protein nano-system and its preparation method were basically the same as those in Example 5, except that in step S2, 50 mg of zein was added to 5 mL of 70% (v / v) ethanol aqueous solution, and finally a zein nanoparticle dispersion was obtained.

[0138] Comparative Example 2:

[0139] Pure zein.

[0140] Comparative Example 3:

[0141] Pure cationic tannin.

[0142] The above nano-systems were detected or tested as follows, and then the test results were analyzed.

[0143] Test Example 1:

[0144] The macroscopic morphology of the nanoparticle suspensions in Examples 1 to 5 and Comparative Example 1 was observed.

[0145] As Figure 2 shown, the CAT-Zein nanoparticle suspensions in Examples 1 to 5 and the zein nanoparticle suspension in Comparative Example 1 all showed a good opalescent state, were well-dispersed, without precipitation or precipitates, and with the increase of the cationic tannin content in Examples 1 to 5, the turbidity of the nano-system gradually decreased; and when the mass ratio of cationic tannin to alcohol-soluble protein in Example 5 was 1:5, the turbidity of the CAT-Zein composite nano-system was the lowest, and showed a lower turbidity and better dispersibility than the zein nanoparticle suspension in Comparative Example 1.

[0146] Test Example 2:

[0147] The particle sizes of the nanoparticle suspensions in Examples 1 to 5 and Comparative Example 1 were measured using a dynamic light scattering (DLS) particle size analyzer. The particle sizes, polydispersity index (PDI), and zeta potential of the nanoparticles are shown in Table 1.

[0148] Table 1 Particle sizes, polydispersity index, and zeta potential of the nanoparticles in Examples 1 to 5 and Comparative Example 1

[0149] Mass ratio of CAT to Zein Particle size / nm Dispersion coefficient Zeta potential / mV Zein 94.34±4.60 0.319±0.028 31.5±1.54 1:5 81.34±2.37 0.353±0.011 56.8±1.87 1:10 97.15±0.95 0.456±0.008 55.6±1.34 1:15 98.11±3.21 0.449±0.004 50.4±1.96 1:20 98.26±1.41 0.438±0.010 42.4±1.94 1:25 98.81±2.03 0.447±0.005 35.7±1.56

[0150] As shown in Table 1, the average particle size of Zein nanoparticles in Comparative Example 1 was 94.34 nm. When cationic tannin was added to form CAT-Zein nanoparticles, as the addition ratio of cationic tannin in Examples 1 to 5 gradually increased from 1:25 to 1:5, the particle size showed a gradually decreasing trend, which was consistent with the conclusion that the turbidity of the nano-system gradually decreased as observed; when the mass ratio of cationic tannin to zein reached 1:5 in Example 5, the average particle size of CAT-Zein nanoparticles was 81.34 nm, significantly lower than the particle size of Zein nanoparticles in Comparative Example 1. This might be due to the interaction between zein and cationic tannin, forming a more compact binary complex of cationic tannin-zein; moreover, the smaller the particle size of the nanoparticles, the better the dispersibility in aqueous solution and the less likely to aggregate and precipitate.

[0151] The PDI value is a measure of the particle size distribution. The smaller the PDI value, the more concentrated the particle size distribution. Generally, a PDI value less than 0.5 is considered the best distribution for a nano-dispersion system; for the Zein nanoparticles in Comparative Example 1 and the CAT-Zein nanoparticles with different mass ratios of cationic tannin / zein in Examples 1 to 5, the PDI values were all below 0.5, so they all had good dispersibility and system stability.

[0152] As the proportion of cationic tannin in CAT-Zein nanoparticles increased from Examples 1 to 5, the Zeta potential gradually increased. The Zeta potential can be used to characterize the surface charge of nanoparticles. The larger the absolute value of the Zeta potential, the higher the stability of the nanoparticles. Therefore, compared with the Zein nanoparticles in Comparative Example 1, the addition of cationic tannin increased the stability of zein nanoparticles, and with the increase in the proportion of cationic tannin, the stability gradually enhanced; when the mass ratio of cationic tannin to zein reached 1:5 in Example 5, the Zeta potential of CAT-Zein nanoparticles was the highest and the stability was the best.

[0153] Generally speaking, when the mass ratio of cationic tannin to zein was 1:5 in Example 5, the dispersion degree and stability of the CAT-Zein nano-system were the best.

[0154] Test Example 3:

[0155] A scanning electron microscope (SEM) was used to observe the microscopic morphology of the nanoparticles in Example 5 and Comparative Example 1.

[0156] As Figures 3 to 6As shown, both the CAT-Zein nanoparticles in Example 5 and the Zein nanoparticles in Comparative Example 1 presented a near-spherical particle morphology, with a smooth surface, a particle size of approximately 100 nm, which was relatively uniform and consistent with the particle size data measured by the particle size analyzer.

[0157] Before the tests in Test Examples 4 to 6, the nanoparticle suspension was freeze-dried overnight for 12 h at -50 °C, and the freeze-dried particle powder was then tested.

[0158] Test Example 4:

[0159] Fourier transform infrared (FTIR) spectroscopy tests were performed on the nanoparticles in Example 5 and the pure products in Comparative Examples 2 and 3.

[0160] As Figure 7 shown, the pure zein and cationic tannin in Comparative Examples 2 and 3 showed characteristic peaks at 3310 cm -1 and 3147 cm -1 respectively. According to previous literature reports, the band at 3100 - 3500 cm -1 is caused by the stretching vibration of hydroxyl groups; when zein and cationic tannin in Example 5 were combined, this band shifted to 3422 cm -1 of the CAT-Zein nanoparticles. This result indicates that there is a strong hydrogen bond interaction between the hydroxyl groups and amide groups in zein and the hydroxyl groups in cationic tannin;

[0161] On the other hand, the characteristic absorption peaks of zein in Comparative Example 2 at 1658 cm -1 and 1537 cm -1 were attributed to the amide I band caused by the stretching vibration of the C=O bond at 1750 - 1600 cm -1 and the amide II band caused by the in-plane bending vibration of the N-H bond and the stretching vibration of the C-N at 1550 - 1510 cm -1 respectively; when zein and cationic tannin in Example 5 were combined, the absorption peak intensities of the amide I band and amide II band of zein decreased significantly, and the amide I band shifted to 1653 cm -1 . This result indicates that there are not only hydrogen bond interactions but also hydrophobic interactions between zein and cationic tannin;

[0162] Therefore, the Fourier transform infrared spectroscopy results indicate that zein and cationic tannin in Example 5 form CAT-Zein nanoparticles through intermolecular forces such as hydrogen bonds and hydrophobic interactions.

[0163] Test Example 5:

[0164] Differential scanning calorimetry (DSC) tests were carried out on the nanoparticles in Example 5 and the pure products in Comparative Examples 2 and 3.

[0165] As Figure 8 shown, the characteristic endothermic peaks of zein in Comparative Example 2 were distributed between 100 and 140 °C, while the characteristic endothermic peaks of cationic tannin in Comparative Example 3 were between 100 and 175 °C; this is related to the evaporation of water in the polymer. The temperature of the hydrophilic cationic tannin is higher than that of the hydrophobic zein because the affinity between the cationic tannin molecules and water molecules is stronger;

[0166] In the differential scanning calorimetry curve of the CAT-Zein nanoparticles in Example 5, the characteristic peaks of cationic tannin disappeared, and a new characteristic endothermic peak appeared at 65.5 °C, indicating that the molecular state of cationic tannin changed after being made into nanoparticles; this result shows that cationic tannin and zein have formed a new complex, rather than just a simple physical mixture, meaning that zein has successfully combined with cationic tannin to form nanoparticles.

[0167] Test Example 6:

[0168] X-ray diffraction (XRD) tests were carried out on the nanoparticles in Example 5 and the pure products in Comparative Examples 2 and 3.

[0169] As Figure 9 shown, zein in Comparative Example 2 had characteristic peaks related to the triple helix crystal structure and the amorphous part at 9.1° and 19.6° respectively; the broad peak at 24.52° in Comparative Example 3 indicated that the cationic tannin was in an amorphous state;

[0170] It should be noted that when zein and cationic tannin formed the CAT-Zein complex in Example 5, the positions of the peaks were basically the same as those of the pure zein in Comparative Example 2, but the intensities of these characteristic peaks generally decreased. This result shows that the addition of cationic tannin reduced the crystal plane diameter, but had no significant effect on the crystal plane spacing; this phenomenon was due to the introduction of cationic tannin, which led to significant changes in the crystal structure or molecular arrangement of zein, changing the intermolecular forces between zein molecules, resulting in a decrease in the intensity of some characteristic absorption peaks. This result was consistent with the previous X-ray diffraction test results on the binding of zein to other hydrophilic substances; this result provided strong evidence for the non-covalent interaction between zein and cationic tannin, and was consistent with the detection results of Fourier transform infrared spectroscopy and differential scanning calorimetry, proving the successful preparation of the CAT-Zein nanoparticles in Example 5.

[0171] Test Example 7:

[0172] The storage stability of the nanoparticles in Example 5 and Comparative Example 1 was investigated, and the specific steps are as follows:

[0173] Take 10 mL of freshly prepared nano-system and store it at 4 °C and 25 °C. Samples are taken on the 0th, 7th, 14th, 21st, and 28th days of storage, and a dynamic light scattering particle size analyzer is used to measure the changes in the particle size, dispersion coefficient, and Zeta potential parameters of the nanoparticles under different storage conditions.

[0174] As Figures 10 to 15 shown, within 28 days of storage, the average particle size of the CAT-Zein nanoparticles in Example 5 and the Zein nanoparticles in Comparative Example 1 is about 100 nm at 4 °C and 25 °C, showing no significant change compared with that at the initial preparation;

[0175] The dispersion coefficients of the particle sizes of the CAT-Zein nanoparticles in Example 5 and the Zein nanoparticles in Comparative Example 1 are always less than 0.5, indicating that the nanoparticles are in a stable dispersion state during long-term storage and no obvious aggregation occurs;

[0176] In addition, the Zeta potentials of the CAT-Zein nanoparticles in Example 5 and the Zein nanoparticles in Comparative Example 1 stored under different temperature conditions are basically in a state of relatively high positive charge, which is also one of the reasons for the long-term stability and non-aggregation of the nanoparticles; Therefore, the CAT-Zein nanoparticles in Example 5 have good storage stability, making them have great potential and feasibility in practical applications.

[0177] The above nano-system was used for the removal of antibiotics in water as follows, and then the application results were analyzed.

[0178] Application Example 1:

[0179] The standard curve of cefalothin sodium was drawn, and the specific steps are as follows:

[0180] Use purified water as a blank control, and use an ultraviolet spectrophotometer to measure the content of cefalothin sodium in the solution at a certain wavelength;

[0181] Weigh 0.010 g of cefalothin sodium and add it to purified water, and make the volume up to 100 mL in a volumetric flask to obtain a 100 mg / L stock solution; the gradient concentrations of cefalothin sodium are set to 10 mg / L, 20 mg / L, 30 mg / L, 40 mg / L, and 50 mg / L. Dilute the stock solution respectively, and measure the ultraviolet absorbance of each sample at a wavelength of 254 nm, and draw the standard curve of ultraviolet absorbance - cefalothin sodium concentration.

[0182] As Figure 16 shown, the equation of the standard curve is y = 0.3996x - 0.0152, R2 = 0.9994, indicating a good linear relationship of the standard curve.

[0183] Application Example 2:

[0184] The removal effect of the nanoparticle suspension in Example 5 and Comparative Example 1 on cefalothin sodium in water was investigated. The specific steps are as follows:

[0185] Take 1 mL of freshly prepared nanoparticle suspension and add it to 30 mL of cefalothin sodium solution at 20 mg / L. Use a magnetic stirrer to stir at a speed of 600 rpm for 1 min at room temperature of 25°C, then stir at a speed of 200 rpm for 4 min, and centrifuge at a speed of 12,000 rpm for 20 min at room temperature of 25°C to collect the supernatant. Use an ultraviolet spectrophotometer to measure the absorbance at a wavelength of 254 nm;

[0186] Calculate the removal rate of cefalothin sodium in the water sample according to the following formula:

[0187]

[0188] In the formula, M 总 represents the total mass of cefalothin sodium added to the nanoparticle suspension, and M 上清液 represents the mass of cefalothin sodium in the supernatant after centrifugation.

[0189] As Figure 17 shown, the removal rate of cefalothin sodium by the Zein nanoparticle suspension in Comparative Example 1 was 41.23% ± 2.54%, and the removal rate of cefalothin sodium by the CAT-Zein nanoparticle suspension in Example 5 was 80.18% ± 1.74%; this result indicates that after adding cationic tannin to zein in Example 5 to form a CAT-Zein composite nanosystem, the ability to remove antibiotics in water has been greatly improved, which is significantly higher than that of the Zein nanosystem in Comparative Example 1.

[0190] Application Example 3:

[0191] The pH value of the nanoparticle suspension in Example 5 was investigated for its stability. The specific steps are as follows:

[0192] Take the freshly prepared nanoparticle suspension and prepare it into different pH values of 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, and 11.0 respectively. Use a dynamic light scattering particle size analyzer to measure the particle size, dispersion coefficient, and Zeta potential of the nanoparticles at different pH values. The parameter changes are shown in Table 2.

[0193] Table 2 Particle size, dispersion coefficient, and Zeta potential of nanoparticles at different pH values in Example 5

[0194] pH value of the dispersion Particle size / nm Dispersion coefficient Zeta potential / mV 3.0 113.47±3.89 0.567±0.057 32.6±0.80 4.0 97.51±1.76 0.545±0.033 35.4±0.88 5.0 104.80±2.53 0.469±0.009 39.5±1.01 6.0 77.66±1.55 0.401±0.003 47.7±0.70 7.0 85.63±3.71 0.471±0.010 36.3±0.79 8.0 117.93±3.35 0.531±0.007 -13.2±0.69 9.0 122.80±4.36 0.551±0.018 -27.7±0.92 10.0 75.65±0.79 0.237±0.005 -31.3±0.56 11.0 179.23±5.27 0.245±0.015 -39.4±0.74

[0195] As shown in Table 2, in Example 5, the particle size of CAT-Zein nanoparticles was almost nearly 100 nm within the measured pH range, and the PDI value was less than or nearly 0.5, with good dispersion, providing a structural guarantee for the subsequent removal of cefotaxime sodium in water bodies.

[0196] In Example 5, the suspension of CAT-Zein nanoparticles showed a positive charge state when the pH value ≤ 7.0; within the pH range of 3.0 - 11.0, as the pH value increased, the Zeta potential of CAT-Zein nanoparticles in Example 5 gradually increased, reached the maximum at pH 6.0, and then gradually decreased, showing a negative charge state at pH 8.0 - 11.0; generally speaking, the greater the absolute value of the Zeta potential of the dispersion in the aqueous phase system, the greater the mutual repulsion force between particles, the less likely to aggregate, and the higher the stability of the particles. Therefore, within the pH range of 3.0 - 11.0, as the Zeta potential first increased and then decreased, the stability of CAT-Zein nanoparticles in Example 5 also first increased and then decreased.

[0197] Application Example 4:

[0198] The effect of pH on the removal of cefotaxime sodium in water by the nanoparticle suspension in Example 5 was investigated, and the specific steps were as follows:

[0199] First, 30 mL of 20 mg / L cefotaxime sodium solutions with different pH values of 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, and 11.0 were prepared. Then, the nanoparticle suspensions with each pH value in Application Example 3 were added to the cefotaxime sodium solutions with corresponding pH values according to the steps in Application Example 2, and the removal rate of cefotaxime sodium in the water samples was calculated.

[0200] As Figure 18 shown, in Example 5, when the nanoparticle suspension of CAT-Zein was under acidic conditions, that is, when the pH value was 3.0 - 6.0, the removal rate of cefotaxime sodium showed an upward trend. This was because the Zeta potential was relatively high at this time, and there was a strong electrostatic attraction between CAT-Zein nanoparticles and negatively charged cefotaxime sodium.

[0201] At pH 6.0, the Zeta potential reached the maximum value of 47.7, and at this time, the removal rate effect of cefotaxime sodium was also the best, reaching nearly 90%; in addition, the greater the absolute value of the Zeta potential, the higher the stability and better the dispersion of the nanoparticles, which was also conducive to the fixation and adsorption of the adsorbate on the surface of the nanoparticles, further optimizing the removal effect of CAT-Zein nanoparticles on cefotaxime sodium.

[0202] When the pH value is between 6.0 and 11.0, the removal rate of cefalothin sodium shows a downward trend, which is consistent with the change trend of the Zeta potential, that is, the electrostatic attraction between CAT-Zein nanoparticles and cefalothin sodium decreases;

[0203] However, due to the adsorption effect of the nanoparticles, when the pH value is at the lower values of 3.0 - 4.0 and the higher values of 10.0 - 11.0, the removal rate of cefalothin sodium by CAT-Zein nanoparticles is still above 50%.

[0204] In the present invention, by adjusting the mass ratio of cationic tannin and zein, a stable cationic tannin-zein composite nanosystem is obtained. Through the characterization of Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction spectroscopy, it is proved that cationic tannin and zein are combined through non-covalent forces such as hydrogen bonds and hydrophobic forces to form a novel nanocomposite; compared with the zein nanosystem, this nanocomposite has a better effect on removing antibiotics from water, and has the best antibiotic removal effect at pH 6.0.

[0205] The composite nanosystem obtained in the present invention has a near-spherical nanoparticle structure, is well dispersed in water, has good storage stability, and has excellent removal effect on antibiotics in water; moreover, this composite nanosystem is natural and green, the raw materials for preparation are cheap and easy to obtain, the preparation method is simple, the cost is low, and no secondary pollution is introduced during water treatment, so it has high popularization and application value.

[0206] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A cationic tannin and alcohol-soluble protein composite nanosystem, characterized in that: The composite nano system is prepared by dissolving cationic tannin and alcohol-soluble protein in an alcohol solution by an anti-solvent dispersion method, and then the alcohol solution is dispersed in water by dripping. In the aqueous solution, the cationic tannin and alcohol-soluble protein interact with each other through non-covalent forces to form nanoparticles through self-assembly. The composite nano system is applied to water treatment.

2. The cationic tannin and prolamin composite nanosystem according to claim 1, characterized in that: The mass ratio of the cationic tannin to the alcohol-soluble protein is 1:(5-25).

3. A method for preparing the cationic tannin and prolamin composite nanosystem as claimed in claim 1 or 2, characterized in that: The method comprises the following steps: S1. Extracting alcohol-soluble proteins from grain powder or grain processing by-products; S2, adding cationic tannins and alcohol-soluble proteins into an alcohol solution and dissolving them by ultrasonication; S3. Drop the alcohol solution into water and stir to obtain a cationic tannin and alcohol-soluble protein composite nanosystem.

4. The method for preparing a cationic tannin and prolamin composite nanosystem according to claim 3, characterized in that: In step S1, alcohol-soluble proteins are extracted from grain powder by first defatting and then alcohol extraction, and the first defatting and then alcohol extraction comprises the following steps: Adding grain powder to a degreasing agent, defatting, collecting precipitation by centrifugation, and drying to obtain defatted grain powder; The defatted grain powder is successively added to a salt solution and then water for extraction, and the supernatant is removed by centrifugation after each extraction; The precipitate after centrifugation is added to the alcohol solution, mixed, and centrifuged to collect the supernatant; The supernatant is concentrated by rotary evaporation, placed in cold storage, centrifuged to collect the precipitate, and freeze-dried to obtain alcohol-soluble protein; The degreasing agent is selected from one or more of n-hexane, ether, petroleum ether, and chloroform-methanol, and the mass ratio of the grain powder to the degreasing agent is 1:(2-8), The degreasing temperature is 10-40°C, the stirring speed is 100-500rpm, and the time is 0.5-4h; The solute of the salt solution is selected from one or more of sodium chloride, potassium chloride, magnesium chloride, and sodium sulfate, the solvent is water, the molar concentration is 0.5-1.5 mol / L, the mass / volume ratio of the defatted grain powder to the salt solution is 1g:(2-8mL), The extraction temperature is 25-65°C, the stirring speed is 100-500rpm, and the time is 0.5-4h; The solute of the alcohol solution is selected from one or more of ethanol, n-propanol, and isopropanol, the solvent is water, and the volume fraction is 40-90%, and the mass / volume ratio of the precipitate to the alcohol solution is 1g:(2-8mL), The mixing temperature is 25-65°C, the stirring speed is 100-500 rpm, and the time is 0.5-4h; The volume of the supernatant was concentrated by rotary evaporation to 1 / 8 to 1 / 2 of the original volume. The refrigeration temperature is 0 to 10° C. and the refrigeration time is 6 to 24 hours.

5. The method for preparing a cationic tannin and prolamin composite nanosystem according to claim 3, characterized in that: In step S1, alcohol-soluble proteins are extracted from food processing byproducts by an alcohol-alkali method, and the alcohol-alkali method comprises the following steps: The food processing byproducts are added to an alcohol solution containing a protein antioxidant protective agent and an alkali, extracted, and the supernatant is collected by centrifugation; The supernatant is diluted, placed in cold storage, the precipitate is collected by centrifugation, washed, and freeze-dried; The freeze-dried powder is added to a degreasing agent, defatted, and the precipitate is collected by centrifugation and dried to obtain alcohol-soluble protein; The protein antioxidant protective agent is selected from one or more of sodium pyrosulfite and sodium bisulfite, the mass concentration of the protein antioxidant protective agent is 0.5-8 g / L, the alkali is selected from one or more of sodium hydroxide and potassium hydroxide, the mass concentration of the alkali is 1.5-5.5 g / L, the solute of the alcohol solution is selected from one or more of ethanol, n-propanol, and isopropanol, the solvent is water, the volume fraction is 60-90%, the mass / volume ratio of the food processing by-product to the alcohol solution is 1 g: (5-15 mL), The extraction temperature is 50-80°C, the stirring speed is 100-500rpm, and the time is 0.5-4h; Dilute the volume fraction of the alcohol solution in the supernatant to 30-60%, The refrigeration temperature is -30 to -10°C and the time is 6 to 24 hours; The degreasing agent is selected from one or more of n-hexane, ether, petroleum ether, and chloroform-methanol, and the mass ratio of the powder to the degreasing agent is 1:(2-8), The degreasing temperature is 10-40° C., the stirring speed is 100-500 rpm, and the time is 0.5-4 hours.

6. The method for preparing a cationic tannin and prolamin composite nanosystem according to claim 3, characterized in that: In step S1, prolamin is extracted from food processing byproducts by an acetic acid method, wherein the acetic acid method comprises the following steps: Adding food processing byproducts into a protein antioxidant protective agent solution, soaking, and filtering to remove the filtrate; The filtered cake was added into acetic acid for extraction, and the supernatant was collected by centrifugation; The pH value of the supernatant is adjusted using an alkaline solution, the solution is refrigerated and centrifuged to collect the precipitate, which is then washed and freeze-dried; The freeze-dried powder is added to a degreasing agent, defatted, and the precipitate is collected by centrifugation and dried to obtain alcohol-soluble protein; The solute of the protein antioxidant protective agent solution is selected from one or more of sodium pyrosulfite and sodium bisulfite, the solvent is water, and the mass concentration is 0.5-8 g / L, and the volume ratio of the food processing byproduct to the protein antioxidant protective agent solution is 1:(2-6), The soaking temperature is 10 to 40° C. and the soaking time is 8 to 24 hours; The mass / volume ratio of the filter cake to acetic acid is 1 g:(2-8 mL), The extraction temperature is 10-40°C, the stirring speed is 100-500rpm, and the time is 0.5-4h; The alkaline solution is a saturated solution, the solute of the alkaline solution is selected from one or more of sodium hydroxide and potassium hydroxide, and the solvent is water. The pH value of the supernatant is adjusted to 4-6, and the adjustment temperature is 1-10°C. The refrigeration temperature is 0 to 10°C and the time is 6 to 24 hours; The degreasing agent is selected from one or more of n-hexane, ether, petroleum ether, and chloroform-methanol, and the mass ratio of the powder to the degreasing agent is 1:(2-8), The degreasing temperature is 10-40° C., the stirring speed is 100-500 rpm, and the time is 0.5-4 hours.

7. The method for preparing a cationic tannin and prolamin composite nanosystem according to claim 3, characterized in that: In step S2, the solute of the alcohol solution is selected from one or more of ethanol, n-propanol, and isopropanol. The solvent is water with a volume fraction of 50-90%. The mass / volume ratio of alcohol-soluble protein to the alcohol solution is (5-15 g):1 L. The frequency of ultrasound is 16 to 24 kHz, the temperature is 10 to 40°C, and the time is 5 to 30 minutes.

8. The method for preparing a cationic tannin and prolamin composite nanosystem according to claim 3, characterized in that: In step S3, the alcohol solution is dripped at a rate of 0.3-1.1 mL / min, and the volume ratio of the alcohol solution to water is 1:(3-7).

9. The method for preparing a cationic tannin and prolamin composite nanosystem according to claim 3, characterized in that: In step S3, the stirring speed is 400-1300 rpm, the temperature is 10-40° C., and the time is 10-60 min.

10. An application of the cationic tannin and prolamin composite nanosystem as claimed in claim 1 or 2, characterized in that: The composite nanosystem removes antibiotics in water bodies with a pH value of 3 to 11.

Images