Preparation and application of a tannin-coupled cottonseed protein composite material for uranium removal

Abstract

The present invention discloses the preparation and application of a tannin-coupled cottonseed protein composite material for uranium removal, comprising: adding cottonseed protein to distilled water under a nitrogen atmosphere, stirring, then adding a hydrogen peroxide solution and ascorbic acid, stirring, to obtain a cottonseed protein mixed solution; adding plant tannin to the cottonseed protein mixed solution to adjust the concentration of the plant tannin in the mixed solution to 0.3 to 1.1 mmol / L, stirring for reaction, dialyzing to remove unreacted plant tannin, and freeze-drying to obtain a tannin-coupled cottonseed protein composite material. The present invention prepares the tannin-coupled cottonseed protein composite material through a free radical-mediated covalent interaction between tannin and cottonseed protein. The tannin-coupled cottonseed protein composite material has the characteristics of a simple preparation method, easy biodegradation, and environmental friendliness. It can achieve rapid and effective separation of uranyl in water environments and on different solid surfaces, and has good application prospects in the safe and efficient treatment of radionuclide contamination in water environments and on solid surfaces.

Description

Technical Field

[0001] The present invention belongs to the technical field of radioactive element processing, and more specifically, relates to the preparation and application of a tannin-coupled cottonseed protein composite material for uranium removal. Background Art

[0002] Tannins are low-cost, renewable natural chemicals with a wide range of sources. They possess a unique structure that reacts with alkaloids, polysaccharides, proteins, metal ions, and other chemicals, making them useful in metal adsorption, food coloring, antioxidants, and leather tanning agents. Tannins can scavenge free radicals and chelate metal ions involved in oxidation reactions. This is attributed to the presence of multiple phenolic hydroxyl groups in tannin molecules, which can donate hydrogen atoms or electrons to neutralize reactive oxygen species and prevent oxidative damage. Bayberry tannin (BT), a condensed tannin, has previously been shown to possess antioxidant and antimicrobial properties.

[0003] Nuclear energy, due to its high efficiency and clean nature, is considered a key candidate for meeting future energy needs. Uranium, currently the most essential nuclear fuel, ensures a stable supply, ensuring its long-term development. However, due to improper disposal of radionuclide-containing wastewater from large-scale nuclear power plants, unpredictable nuclear accidents, nuclear waste reprocessing, oil and gas leaks, land-based uranium mining, and military operations, radioactive uranium is released into the environment, posing a serious threat to human health and ecological security. During the operation and decommissioning of nuclear power plants, contact with radioactively contaminated surfaces of machinery and components poses a significant risk to the health and safety of workers, clothing, and the environment. Therefore, effective and timely research on surface radioactive decontamination is as important as environmental remediation.

[0004] Currently, chemical precipitation, oxidation, and adsorption are conventional technologies for removing metal ions from aqueous environments. However, these technologies suffer from disadvantages such as high cost, poor effectiveness, and potential for secondary pollution. Compared to traditional methods for treating aquatic environments contaminated by metal ions, ion flotation offers several key advantages, including shorter treatment times, minimal space requirements, low energy consumption, and ion selectivity. Foam purification effectively prevents surface corrosion, significantly reduces waste generation, and can be used to clean complex solid surfaces. Surfactants used in ion flotation pose environmental risks, are chemically unstable, bioaccumulate, are costly, and are non-biodegradable. Therefore, for the commercial application of ion flotation, environmentally friendly and efficient materials that can both chelate and foam are urgently needed. The synergistic effect between the numerous phenolic hydroxyl groups in tannin molecules explains its remarkable complexing ability with metal ions. However, its high solubility makes it difficult to use in aqueous environments, and modification is often required for its effectiveness. Summary of the Invention

[0005] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0006] In order to achieve these objects and other advantages of the present invention, a method for preparing a tannin-coupled cottonseed protein composite material for uranium removal is provided, comprising the following steps:

[0007] Step 1: Add cottonseed protein to distilled water under a nitrogen atmosphere, stir, then add hydrogen peroxide solution and ascorbic acid, and continue stirring to obtain a cottonseed protein mixture;

[0008] Step 2: Add plant tannins to the cottonseed protein mixture to make the concentration of plant tannins in the mixture be 0.3-1.1 mmol / L, stir to react, dialyze to remove unreacted plant tannins, and freeze-dry to obtain a tannin-coupled cottonseed protein composite material, namely CPI-BT.

[0009] Preferably, in step 1, the mass volume ratio of cottonseed protein to distilled water is 1 g:50-150 mL.

[0010] Preferably, in step 1, the stirring temperature is 20-30° C., and the stirring time is 1-3 h.

[0011] Preferably, in step 1, the concentration of the hydrogen peroxide solution is 0.5 to 1.5 mol / L.

[0012] Preferably, in step 1, the mass volume ratio of cottonseed protein to hydrogen peroxide solution is 1 g:1-5 mL; and the mass ratio of cottonseed protein to ascorbic acid is 1:0.2-0.7.

[0013] Preferably, in step 2, the plant tannin is one or more of bayberry tannin, persimmon tannin, apple tannin, tea tannin and grape tannin.

[0014] Preferably, in the step 2, the stirring reaction temperature is 20-30°C and the time is 20-30h; freeze drying is freeze drying at -100-50°C for 40-60h.

[0015] Preferably, the method further comprises modifying the prepared tannin-coupled cottonseed protein composite material:

[0016] S1. Add the prepared tannin-coupled cottonseed protein composite material to a 50-80 wt% ethanol solution, then add ferrous chloride and polyethylene glycol-400, adjust the pH to 2-3, and stir at 20-30° C. and 100-200 rpm for 2-4 hours to obtain a mixed solution A;

[0017] S2. Add tetrabutyl titanate and citric acid to the mixed solution A, adjust the pH to 3-5, and stir at 40-50° C. and 100-200 rpm for 2-4 hours to obtain a mixed solution B;

[0018] S3. Add 50-200 mL of 0.1-0.5 mol / L sodium borohydride solution to the mixed solution B, stir at 20-30° C. and 100-200 rpm for 1-3 h, then centrifuge to collect the precipitate, wash it, and freeze-dry it to obtain a modified tannin-coupled cottonseed protein composite material.

[0019] Preferably, in S1, the mass volume ratio of the tannin-coupled cottonseed protein composite material, the ethanol solution, ferrous chloride and polyethylene glycol-400 is 1 g:100-300 mL:0.05-0.2 g:0.05-0.2 g.

[0020] Preferably, in S2, the mass ratio of tetrabutyl titanate, citric acid and the tannin-coupled cottonseed protein composite material in step 1 is 0.1-0.5:0.05-0.2:1.

[0021] Application of a tannin-coupled cottonseed protein composite material prepared by the preparation method described above in uranium removal in water environments.

[0022] The invention discloses an application of a tannin-coupled cottonseed protein composite material prepared by the preparation method described above in removing uranium from textile materials.

[0023] The invention discloses an application of a tannin-coupled cottonseed protein composite material prepared by the preparation method described above in removing uranium from the surfaces of glass, metal and ceramics.

[0024] The present invention includes at least the following beneficial effects: the present invention prepares a tannin-coupled cottonseed protein composite material through a free radical-mediated covalent interaction between tannin and cottonseed protein (CPI), utilizes the abundant ortho-phenolic hydroxyl groups in the tannin structure and the amino and carboxyl groups of cottonseed protein to coordinate with uranyl ions, thereby realizing rapid and effective separation of uranyl in water environments and on different solid surfaces. The tannin-coupled cottonseed protein composite material of the present invention has the characteristics of simple preparation method, easy biodegradation, and environmental friendliness, and has good application prospects in the safe and efficient treatment of radionuclide contamination in water environments and solid surfaces. In addition, the CPI-BT prepared by the present invention is a very promising alternative to chemical surfactants in the food, pharmaceutical and non-food industries, and provides new insights into the application of antioxidant emulsifiers as a safe and low-cost emulsifier in the remediation of water environments or solid surfaces contaminated by radionuclides.

[0025] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1The polyphenol content (A), binding rate and degree of substitution (B) of the tannin-coupled cottonseed protein composite materials prepared in Examples 1 to 3;

[0027] Figure 2 FTIR images of the tannin-coupled cottonseed protein composite materials and CPI prepared in Examples 1 to 3;

[0028] Figure 3 CD spectra of the tannin-coupled cottonseed protein composite material and CPI prepared in Example 3;

[0029] Figure 4 This is the XPS graph of the tannin-coupled cottonseed protein composite material and CPI prepared in Example 3;

[0030] Figure 5 This is an SEM image of the tannin-coupled cottonseed protein composite material and CPI prepared in Example 3;

[0031] Figure 6 This is the contact angle image of the tannin-coupled cottonseed protein composite material prepared in Example 3 and the CPI solution on the paraffin surface;

[0032] Figure 7 Surface tension diagram of the tannin-coupled cottonseed protein composite material and CPI prepared in Example 3;

[0033] Figure 8 The foaming ability and foam stability of the tannin-coupled cottonseed protein composite material and CPI prepared in Example 3;

[0034] Figure 9 Comparison chart of EAI (A) and ESI (B) of the tannin-coupled cottonseed protein composite material and CPI prepared in Example 3;

[0035] Figure 10 This is a comparison chart of the DPPH radical scavenging activities of the tannin-coupled cottonseed protein composite material prepared in Example 3 and CPI and BT at different concentrations;

[0036] Figure 11 This is a comparison chart of the ABTS free radical scavenging activity of the tannin-coupled cottonseed protein composite material prepared in Example 3 and CPI and BT at different concentrations;

[0037] Figure 12 A is the adsorption capacity of the tannin-coupled cottonseed protein composite material prepared in Example 3 at different pH values; Figure 12 B is the adsorption capacity and uranium removal rate of the tannin-coupled cottonseed protein composite material prepared in Example 3 at different dosages;

[0038] Figure 13 The adsorption capacity of the tannin-coupled cottonseed protein composite material prepared in Example 3 under different ventilation rates;

[0039] Figure 14 The adsorption capacity change over time (A) and the kinetic fitting curve of the removal process (B) of the tannin-coupled cottonseed protein composite material prepared in Example 3;

[0040] Figure 15 The uranium adsorption capacity of the tannin-coupled cottonseed protein composite material prepared in Example 3 in a coexisting ion system;

[0041] Figure 16 The tannin-coupled cottonseed protein composite material prepared in Example 3 was prepared under different UO2 2+ Adsorption capacity at initial concentration (A), linear fitting of Langmuir model (B), linear fitting of Freundlich model (C), and linear fitting of Temkin model (D);

[0042] Figure 17 A is UO2 2+ SEM images and elemental composition of CPI-BT-U after adsorption; Figure 17 B is the FTIR images of CPI-BT and CPI-BT-U; Figure 17 C is the EDS mapping image of CPI-BT-U;

[0043] Figure 18 A is the XPS spectra of CPI-BT and CPI-BT-U; Figure 18 B is the U4f high-resolution spectrum of CPI-BT-U; Figure 18 C is the high-resolution N1s spectrum of CPI-BT-U; Figure 18 D is the O1s high-resolution spectrum of CPI-BT-U;

[0044] Figure 19 The stain removal rates of the tannin-coupled cottonseed protein composite material prepared in Example 3 on cotton fabric (A), ceramic (B), glass (C), and metal (D). DETAILED DESCRIPTION

[0045] The present invention is further described in detail below with reference to the embodiments so that those skilled in the art can implement the invention with reference to the description.

[0046] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0047] Example 1

[0048] A method for preparing a tannin-coupled cottonseed protein composite material for uranium removal comprises:

[0049] Step 1: Under a nitrogen atmosphere, add 1 g of cottonseed protein to 100 mL of distilled water, stir for 2 h, then add 2 mL of 1.0 M hydrogen peroxide solution and 0.5 g of ascorbic acid, and stir at 25 ° C for 2 h to obtain a cottonseed protein mixture;

[0050] Step 2: Add bayberry tannin to the cottonseed protein mixture to make the concentration of bayberry tannin in the mixture 0.35 mM, stir and react at 25°C for 24 hours, dialyze to remove unreacted bayberry tannin, and freeze-dry at -80°C for 48 hours to obtain a tannin-coupled cottonseed protein composite material, namely CPI-BT 0.35.

[0051] Example 2

[0052] In this example, the concentration of bayberry tannin is 0.70 mM, and the remaining steps are the same as in Example 1 to prepare CPI-BT 0.70.

[0053] Example 3

[0054] In this example, the concentration of bayberry tannin is 1.05 mM, and the remaining steps are the same as in Example 1 to prepare CPI-BT 1.05.

[0055] The total phenol content, incorporation rate, and degree of substitution were determined using the Folin-Ciocalteu reagent method: 1 mL of a 1 mg / mL sample solution, 3 mL of distilled water, 1 mL of Folin-Ciocalteu reagent (1 M), and 3 mL of NaCO (7.5 wt%) were mixed in a 10-mL centrifuge tube. The resulting mixture was incubated in the dark at room temperature for 1 hour. The absorbance of the mixture was measured at 765 nm using a UV-visible spectrophotometer (UV-5500PC, Metash, Shanghai, China). A standard curve was constructed using gallic acid standards ranging from 0.05 to 0.25 mg / mL, with water used as a blank. The BT equivalent content in CPI-BT was expressed as mg BT equivalent per gram of CPI-BT (mg BTE / g). The incorporation rate and degree of substitution were calculated as follows:

[0056]

[0057] The polyphenol content, binding rate and substitution degree of the tannin-coupled cottonseed protein composite materials prepared in Examples 1 to 3 are as follows: Figure 1 shown. Figure 1 A shows that the content of protein-bound polyphenols in CPI-BT increased significantly with the increase of BT concentration (0.35-1.05 mM). At 1.05 mM BT, the maximum value observed was 108.88 BTE mg / g. This may be because there are more opportunities for nucleophilic addition events to occur at high BT concentrations, thereby increasing the degree of cross-linking. Figure 1Figure B shows the binding rate between CPI and BT, which increases significantly from 0.35 to 0.70 mM but remains almost unchanged after further increasing the BT concentration. However, the degree of substitution increases significantly with increasing BT concentration. These analyses confirm the strong binding of BT to CPI and the successful synthesis of CPI-BT.

[0058] FTIR is used to characterize the changes in the secondary structure of proteins after grafting with BT to form a conjugate. Figure 2 The FTIR images of the tannin-coupled cottonseed protein composites and CPI prepared in Examples 1 to 3 are shown. It can be seen that the four important peaks correspond to four different amide bonds, namely, amide A (~3372.74 cm -1 ), Amide I (~1652.21cm -1 )、Amide II (~1545.61cm -1 ) and amide III (~1396.98 cm -1 Compared with CPI, these bands in CPI-BT changed in both peak position and shape, indicating that the secondary structure of CPI in the conjugate changed. After CPI binding, the intensity of the amide peak increased and became more pronounced with increasing BT concentration. Due to CPI-BT binding, the peak position of amide I shifted from 1652.21 cm in CPI to 1652.21 cm in CPI. -1 Move slightly to 1647.62cm -1 ; Compared with CPI, the intensity of the amide II peak in the CPI-BT spectrum is significantly higher, indicating more CN stretching, accompanied by NH bending mode. The increase in intensity may be due to the increase in the number of amide bonds caused by the binding of phenolic compounds to proteins.

[0059] Figure 3 CD spectra of the tannin-coupled cottonseed protein composite material and CPI prepared in Example 3. It can be seen that there are significant differences between the spectral trends of CPI and CPI-BT. The molar ellipticity of CPI and CPI-BT has decreased significantly, and the peak has blue-shifted from 197.02nm to 192.84nm. There is also a significant negative attenuation of the peak at 225nm, indicating the loss of α-helix in CPI. This loss indicates that a certain degree of unfolding has occurred in the protein structure. These changes indicate that the overall structure has not been maintained, and the coupling process has changed the conformation of CPI and the structural content between the protein secondary structures.

[0060] XPS was used to analyze the effect of BT grafting on the chemical composition distribution of CPI. Figure 4As shown, the surface of CPI is primarily composed of C, N, and O. After the coupling process, the XPS spectrum of CPI-BT shows no distinct new bands, comparable to native CPI. The characteristic peak at 400 eV associated with C=N and CN exhibits higher intensity. This result further confirms the successful incorporation of BT into the CPI backbone.

[0061] Figure 5 This is an SEM image of the tannin-coated cottonseed protein composite material and CPI prepared in Example 3. It can be seen that the CPI particles are dense and relatively smooth and compact, while the CPI-BT particles are relatively loose, with increased surface roughness and the presence of small pores. BT is a highly hydrophilic molecule, so its grafting onto the protein alters the molecular structure, as shown by FTIR and CD analysis and the hydrophilic / hydrophobic ratio of CPI. These changes create favorable conditions for its interaction with water molecules.

[0062] The assessment of surface hydrophobicity can usually be achieved through contact angle analysis. Figure 6 Contact angle values ​​and images of the tannin-coupled cottonseed protein composite material and CPI solution prepared in Example 3 on a paraffin surface. As can be seen, the contact angle between water and the paraffin block surface is 134.0°, indicating that the paraffin is barely wetted. However, after the addition of CPI, the contact angle between water and the paraffin decreases, becoming even more pronounced with the addition of CPI-BT, with the contact angle dropping from 134.0° for water to 101.2° for CPI and further to 92.5° for CPI-BT. This indicates that CPI-BT exhibits good hydrophilicity, likely due to the increased carboxyl content during the deamidation reaction.

[0063] Figure 7 Figure 3 shows the surface tension of the tannin-coupled cottonseed protein composite material and CPI prepared in Example 3. CPI and CPI-BT solutions were prepared in distilled water at concentrations ranging from 0.1 to 1 mg / mL. The surface tension of CPI and CPI-BT was analyzed using a tensiometer K100 (Kruss, Germany) and the Du Noüy ring method. It can be seen that the surface tension decreases rapidly within the first 50 seconds, then decreases slowly and steadily, and levels off. Protein molecules in aqueous solution typically fold into a coiled shape to conceal the hydrophobic region at the center of the coil and expose the hydrophilic groups to the water. On the other hand, when a protein molecule approaches the air-water interface, it partially unfolds and aligns its hydrophobic groups toward the air phase. At all concentrations, CPI-BT reduced the surface tension between the solution and the air phase, achieving a superior effect compared to CPI. The higher the protein concentration, the greater the reduction in surface tension, suggesting that CPI-BT has a better ability to reduce surface tension than CPI, likely due to partial unfolding during the binding process.

[0064] Both the structural and functional properties of proteins are affected by the binding of proteins to polyphenols. Therefore, the way in which proteins and polyphenols interact can enhance the latter's ability to resist oxidation and form foams or emulsions. Changes in the secondary and tertiary structures of CPIs can affect their surface charge density and spatial conformation, ultimately affecting their functionality. Figure 8 The foaming ability and foam stability of the tannin-coupled cottonseed protein composite material and CPI prepared in Example 3. It can be seen that after coupling CPI with BT, the foaming ability and foam stability are significantly increased. Generally speaking, the ability of an emulsifier to reduce the surface tension of water is the reason for its foaming property. The more the emulsifier can reduce the surface tension of water, the more foam it produces, and vice versa. After standing for 30 minutes, the foam of both samples decreased. The large interface between the gas phase and the liquid phase, coupled with strong thermodynamic instability, can cause leakage, weakening, gas diffusion and bubble defoaming of the liquid film layer. The foaming ability of CPI-BT (52.8%) is significantly higher than that of CPI (13.3%). Therefore, covalent coupling significantly improves the stability of the protein membrane.

[0065] Emulsifying capacity is a measure of a protein's ability to adsorb at the oil-water interface. It represents the interfacial area per unit weight of protein that can be stabilized. Emulsifying capacity is typically assessed using EAI and ESI; higher EAI and ESI values ​​indicate stronger emulsifying capacity. Figure 9 Figures A and 9B are the EAI and ESI comparison diagrams of the tannin-coupled cottonseed protein composite material and CPI prepared in Example 3, respectively. It can be seen that the EAI and ESI of CPI-BT are higher than those of CPI. The concentration of protein also greatly affects the EAI. When the concentration of all samples increases from 5 mg / mL to 10 mg / mL, the EAI values ​​decrease. However, the EAI of CPI-BT is 27.24% higher than that of CPI. In addition, the ESI value of CPI-BT increases, which means that the stability of the emulsion is better than that of CPI. This can be attributed to the increase in hydrophilicity and the increase in exposed hydrophobic sites, which promotes the interaction between the protein and the interface of nearby oil droplets.

[0066] Antioxidant activity test

[0067] (1) ABTS free radical scavenging test

[0068] Prepare an ABTS (7.0 mM) solution containing potassium persulfate (2.5 mM) and store in the dark for 16 h. Dilute with water to obtain a working solution with an absorbance of 0.70 ± 0.04 at 734 nm. Add the sample solution (1 mL, 0.5, 1 mg / mL) to 4 mL of the working solution and shake well. Incubate the mixture at room temperature in the dark for 20 min. Measure the absorbance at 734 nm using a spectrophotometer. Calculate the ABTS radical scavenging rate using the following formula:

[0069] ABTS free radical scavenging rate (%) = (Ac-As) / Ac×100%

[0070] Where As is the absorbance of the working solution after adding the sample solution, and Ac is the absorbance of the negative control prepared with phosphate buffer (100 mM, pH 7.0);

[0071] (2) DPPH free radical scavenging test

[0072] The sample solution (2 mL, 0.5, 1 mg / mL) was mixed with 3 mL of DPPH solution (0.004% methanol solution) and reacted at room temperature in the dark for 30 min. The absorbance was measured at 517 nm using a spectrophotometer, and the DPPH radical scavenging rate was calculated using the following formula:

[0073] DPPH free radical scavenging rate (%) = (Ac-As) / Ac×100%

[0074] Where As is the absorbance of the DPPH solution after adding the sample solution, and Ac is the absorbance of the negative control prepared with phosphate buffer (100 mM, pH 7.0).

[0075] Cottonseed protein is a good source of bioactive peptides with excellent antioxidant activity; however, they have limitations such as poor solubility and stability in aqueous environments. BT exhibits high antioxidant activity and solubility. The interaction between CPI and BT in the composite material may produce a synergistic effect, resulting in greater antioxidant activity and improved performance. The DPPH radical is a stable free radical that can abstract a hydrogen atom from antioxidants to form the stable DPPH-H molecule. Therefore, the DPPH test is often used to evaluate the primary antioxidant capacity of a compound. Figure 10 The DPPH radical scavenging activity comparison chart for the tannin-coupled cottonseed protein composite material prepared in Example 3, as well as CPI and BT at different concentrations (0.5 mg / mL and 1 mg / mL) shows that BT exhibited excellent DPPH scavenging activity (>85%) at all tested concentrations, while the scavenging activity of CPI was less than 21.3%. The scavenging activity of CPI-BT was significantly higher than that of CPI. In the scavenging reaction tested in this test, the extent of the reaction depends on the hydrogen-donating capacity of the antioxidant. Since BT is known to be a rich source of adjacent phenolic hydroxyl groups and has significant metal binding capacity, the improvement in the scavenging activity of CPI-BT can be attributed to the free hydroxyl groups from BT introduced into CPI after binding. These results indicate that the introduction of BT into CPI can provide the resulting composite with strong DPPH radical scavenging activity.

[0076] Figure 11This is a comparison chart of the ABTS free radical scavenging activity of the tannin-coupled cottonseed protein composite material prepared in Example 3 and CPI and BT at different concentrations (0.5 mg / mL and 1 mg / mL). It can be seen that BT exhibited excellent ABTS scavenging activity (>90%) at all tested concentrations, while the scavenging activity of CPI was less than 59%, and the scavenging activity of CPI-BT was 28% higher than that of CPI. It is reported that peptides with more hydrophilic groups react easily with ABTS. Therefore, since the hydrophilicity of CPI increases after the hydrophilic BT is conjugated to CPI, this may help to improve the scavenging activity of CPI-BT. These results indicate that when BT is introduced into CPI, the resulting composite material has a significant ABTS free radical scavenging effect.

[0077] Uranium removal test in water environment (ion flotation method): The foaming device consists of a column 300 mm high and 30 mm in diameter; a porous sintered material that can form tiny bubbles with a diameter of about 2 mm; a uranyl nitrate solution is prepared, in which UO2 2+ The concentration is 20 mg / L, and the pH is adjusted to 6 using 0.1 M sodium hydroxide and 0.1 M HNO3. 100 mL of uranyl nitrate solution and 20 mg of sample are added to a conical flask, weighed and thoroughly mixed. Then, the mixture is transferred to a foaming device and an air pump is used to generate foam in the column at a ventilation rate of 2.0 L / min. During this process, the emulsifier bubbles quickly condense with the UO2 in the solution. 2+ The complex was formed and the reaction temperature was 25°C for 30 min. Each sample was collected approximately 5 cm above the porous sinter, and the outlet foam was collected into a conical flask using an outlet tube. Arsenazo III was used as a complexing agent and color developer, and UO2 was detected using a UV-visible spectrophotometer (UV-5500PC, Metash, Shanghai, China). 2+ Concentration, each test was repeated three times or more, and the average value was taken for analysis. e The uranium removal rate RE is expressed by the following formula:

[0078]

[0079] Where C0 and C e Represents UO2 before and after removal 2+ concentration (mg / L), V is the volume of the solution used (L), Q e is the adsorption capacity (mg / g), W is the mass of the sample (g), and RE is the uranium removal efficiency (%).

[0080] The equilibrium time data were removed by fitting the pseudo-first-order and pseudo-second-order adsorption equations, and the nonlinear expression of the pseudo-first-order adsorption was calculated as follows:

[0081]

[0082] The nonlinear expression of pseudo-secondary adsorption is calculated as follows:

[0083]

[0084] Where t represents the reaction time (min), q e and q t represent the adsorption capacity at equilibrium and at any time (mg / g), K1 is the pseudo-first-order adsorption rate constant (g mg -1 min -1 ), K2 is the pseudo-secondary adsorption rate constant (g mg -1 min -1 );

[0085] Initial concentration of UO2 2+ The removal rate influence data were fitted using the Langmuir and Freundlich models. The expressions of the Langmuir and Freundlich models are as follows:

[0086]

[0087] Where q e Indicates UO2 2+ Equilibrium adsorption capacity (mg / g), q max represents the saturated adsorption capacity (mg / g) in the Langmuir model, C0 and C e UO2 at the beginning and after the reaction 2+ Concentration (mg / L), K L is the Langmuir model constant, which is determined by the exchange equilibrium constant (L / mg), K F is the Freundlich constant (mg / g)(L / mg) 1 / n , 1 / n represents the coefficient of adsorption site heterogeneity.

[0088] Figure 12 A is the adsorption capacity of the tannin-coupled cottonseed protein composite material prepared in Example 3 at different pH values ​​(4.0-9.0); Figure 12 Figure B shows the adsorption capacity and uranium removal rate of the tannin-coupled cottonseed protein composite material prepared in Example 3 at different dosages (10-50 mg). Generally speaking, the initial pH value of the solution has a significant effect on the removal of metal ions. This experiment investigated the effect of pH on the uranium removal ability of CPI-BT. Figure 12A illustrates how pH (4.0-9.0) affects the uranium removal capacity of CPI-BT. The adsorption capacity increases with increasing pH, reaches a maximum at pH 6, and then decreases with further increases in pH. The pH value may have an effect on the functional groups of the emulsifier, the ionic balance of the medium, and the surface charge. The results show that the adsorption performance first increases and then decreases. In the pH range of 4.0 to 6.0, the adsorption capacity increases significantly from 60.48 mg / g to 99.08 mg / g, and then decreases to 74.36 mg / g at pH 9.0. The main reason for this may be the H generated at lower pH values. + The number of phenolic hydroxyl groups is large, which makes it easy for adsorption sites such as phenolic hydroxyl groups to be protonated and leads to electrostatic repulsion between the protonated adsorbent and the positively charged adsorbent; at higher pH values, these groups can also be deprotonated, thereby reducing the binding sites available for adsorption. In addition, at higher pH values, foam is formed rapidly and therefore cannot fully contact with the adsorbent, resulting in lower removal capacity. This shows that CPI-BT is suitable for uranium adsorption under weakly acidic and neutral conditions. Therefore, pH 6 was selected for all subsequent tests. Figure 12 As shown in Figure B, as the amount of CPI-BT increases from 10 mg to 50 mg, the adsorption capacity gradually decreases, but the removal rate increases sharply. When the amount is 50 mg, the removal rate of CPI-BT is 97.2%, which is a high removal efficiency. This can be attributed to the increase in the surface area of ​​CPI-BT, which provides more available binding sites, and the UO2 in the solution. 2+ The supply of CPI-BT is limited, and the excess reaction sites are still unsaturated. In view of the high adsorption capacity and removal rate of CPI-BT, 20 mg was selected as the optimal adsorbent dosage.

[0089] Figure 13 The adsorption capacity of the tannin-coupled cottonseed protein composite prepared in Example 3 at different aeration rates is shown. As can be seen, foam formation is slower in the aeration range of 0 to 2.0 L / min, making complete surface removal more difficult at lower flow rates. Increasing aeration capacity increases removal capacity with increasing gas flow rate, but this improvement is not significant. This phenomenon may be due to the increased bubble collapse and the resulting detachment of ions adhering to the foam.

[0090] Figure 14 A is the change of adsorption capacity of tannin-coupled cottonseed protein composite material prepared in Example 3 over time. It can be seen that as time goes by, UO2 2+ was removed rapidly and reached the peak in less than 30 minutes. Therefore, the adsorption equilibrium time was 30 minutes, indicating that the UO2 2+Can be completely removed. Due to the sufficient number of active chelating sites on CPI-BT, the removal process proceeds quickly. In the initial removal stage, sufficient binding sites of CPI-BT can be quickly chelated. As the adsorption process proceeds, the available binding sites become fewer and fewer, thus slowing down the removal speed.

[0091] The obtained kinetic data were fitted using pseudo-first-order and pseudo-second-order kinetic models to understand the adsorption mechanism. The fitting curve results are shown in Figure 2. Figure 14 B and Table 1. It can be seen that UO2 2+ More than 90% of the adsorption equilibrium occurs within the first 10 minutes, and then slowly increases over the next 90 minutes. The pseudo-second-order linear model can more accurately describe the elimination process. The UO2 calculated by the pseudo-second-order model is 2+ Adsorption capacity (q e-cal , 97.734 mg / g) and the actual result (q e-exp , 99.077 mg / g). This result indicates that chemical reaction plays a leading role in the removal process.

[0092] Table 1

[0093]

[0094] Since other metal ions are often present in radioactive contaminated areas, one of the challenges in the practical application of decontamination agents is the degradation of UO2. 2+ In order to examine the effect of other ions on the removal performance of CPI-BT, the removal of UO2 by CPI-BT was studied. 2+ The removal selectivity, such as Figure 15 As shown. CPI-BT in binary solution from the 2+ Mg 2+ 、Ni 2+ 、Sr 2+ and Zn 2+ (10~40mg / L) adsorption of UO2 in nuclear wastewater 2+ The experimental results show that CPI-BT has a good selectivity for UO2 2+ It has high selectivity and is 2+ Mg 2+ 、Ni 2+ and Sr 2+ ) in the presence of Zn. As the initial concentrations of these competing ions increased or decreased, the adsorption capacity did not change much. This indicates that the presence of other metal ions had no significant effect on the removal. However, in the presence of Zn 2+ In the presence of Zn, the adsorption capacity of CPI-BT decreased by about 30 mg / g, which was significantly lower than that of other cations, indicating that CPI-BT has a strong effect on the adsorption of Zn.2+ The binding capacity can be attributed to the protein component of the adsorbent. 2+ Dominated the adsorption sites of CPI-BT.

[0095] Figure 16 A is the tannin-coupled cottonseed protein composite material prepared in Example 3 at different UO2 2+ Adsorption capacity at initial concentration. The results show that the adsorption capacity increases with the increase of concentration and reaches a maximum of 310.15 mg / g at a concentration of 320 mg / L. 2+ concentration has not been fully occupied, so the adsorbed UO2 2+ On the contrary, at high UO2 2+ At this concentration, the binding sites on CPI-BT are occupied and cannot bind more UO2 2+ When studying this process, it is crucial to understand the basic physicochemical behavior of the adsorption process as shown by the adsorption isotherm. 2+ The adsorption process can be described by the Freundlich and Langmuir isotherm models. These models explain some parameters related to the removal mechanism, including the surface characteristics of the adsorbent, its affinity for the adsorbate, and its removal capacity. Figure 16 BD and Table 2 show the fitting results. It is observed that CPI-BT has a great influence on UO2 2+ The removal of isotherm is very consistent with the Langmuir isotherm model, and the regression coefficient is (R 2 >0.96). This indicates that the adsorption occurs on a homogeneous monolayer surface. According to the Langmuir model, CPI-BT has a strong affinity for UO2. 2+ The maximum removal capacity of CPI-BT was 224.72 mg / g. Therefore, CPI-BT can be used as a productive adsorbent.

[0096] Table 2

[0097]

[0098] After the uranium removal test, the resulting solution was collected and vacuum filtered using a 0.22 μm membrane, and the filtrate was then dried and used for subsequent characterization analysis. Figure 17 A is UO2 2+ SEM image and elemental composition of CPI-BT-U after adsorption. It can be seen that the adsorption of UO2 2+ After that, the surface of CPI-BT-U has the following characteristics: increased pores, increased roughness, and finer particle shape; CPI-BT is mainly composed of C, O, and N atoms, however, a new peak appears in CPI-BT-U, indicating that UO2 2+ It has been successfully adsorbed onto the composite material. Figure 17 The EDS mapping image shown in C shows that UO2 2+ is highly dispersed throughout the material, indicating that a large fraction of UO2 2+ has been adsorbed on the active sites of CPI-BT, which also confirms that UO2 2+ is on the CPI-BT surface, as proposed by the Langmuir model above.

[0099] FTIR was used to study the changes in functional groups on CPI-BT after uranium removal experiments. Figure 17 As shown in B, after adsorption, the intensities of multiple peaks increased or decreased, and a new peak appeared. -1 A new peak appears at , which can be attributed to the stretching vibration of O=U=O, which proves that UO2 2+ Successfully chelated with CPI-BT. 3430cm -1 The peak at 1224 cm-1 is broadened, which is attributed to the strong stretching vibration of -OH and -NH. -1 The peak at (typical phenolic hydroxyl peak) is obviously weakened, which indicates that UO2 2+ The substances removed include phenolic hydroxyl groups. The amide I, II and III bands of proteins are located at 1652 cm -1 、1535cm -1 and 1365cm -1 In addition, -C=O and -NH groups promote the UO2 2+ This is evidenced by the weaker peak intensities of the amide I, II, and III bands of CPI-BT-U.

[0100] To further understand the valence state of U adsorbed on CPI-BT, the N1s and O1s XPS spectra were analyzed. Figure 18 A shows the XPS spectra of CPI-BT before and after uranium removal test, UO2 2+ The treatment resulted in the appearance of a new signal peak in the XPS full spectrum, which was U4f, indicating that UO2 2+ It was successfully adsorbed onto CPI-BT, which was consistent with the results of FTIR and EDS analysis. Figure 18 Figure B shows the high-resolution spectrum of U4f, in which five peaks are identified. The peaks at 380.40 eV and 391.25 eV are attributed to U(IV), while the peaks at 382.09 eV, 385.57 eV, and 392.90 eV are attributed to U(VI). The functional groups contained in the protein or polyphenol in the composite material can act as electron donors, promoting the reduction of U(VI) to U(IV) during the adsorption process.

[0101] In the N1s XPS high-resolution spectrum ( Figure 18C), three peaks similar to those of natural CPI-BT were observed. However, the peaks at 400.68eV, 399.38eV, and 397.98eV in CPI-BT shifted. After the experiment, the peak of CN shifted to 399.28eV. This shift may be due to the change in the electron density around the N atom when interacting with uranium. Due to the attraction of the outer electrons of the positive metal ions, the electron density of N decreases, resulting in higher bonding energy. In the O1s XPS high-resolution spectrum ( Figure 18 In D), the two overlapping peaks at 532.28 eV and 530.98 eV correspond to C=O and COR, respectively. 2+ After adsorption, the peak position corresponding to COR shifted from 531.08 eV, which may be because the outer electrons of the O atoms were attracted by the positively charged metal ions, increasing their bonding energy. The results also showed that the carboxyl groups on CPI participated in the adsorption process. In fact, through covalent bonds, both -NH and -C=O groups can donate lone electron pairs and bind to UO2 2+ Chelation, CPI-BT for UO2 2+ The adsorption is mainly due to UO2 2+ The chelation process between the phenolic hydroxyl groups of BT combined with CPI. In addition, the -C=O and -NH of CPI are the 2+ Active sites for chelation.

[0102] Uranium purification performance test for fabric materials: A 5 cm x 5 cm piece of cotton fabric was uniformly cut. Before uranium contamination was simulated on the fabric, its natural background value (A0) was measured using an α / β surface contamination meter (RJ39-2060, Shanghai Ergonomics Testing Instrument Co., Ltd., Shanghai, China). The fabric was then uniformly soaked in 1 mL of a 4.75 g / L uranium solution for contamination and then dried at 40°C. After the fabric was completely dry, its radioactivity value (A1) was measured. The dried fabric was stirred at 180 rpm in water / CPI-BT solutions of varying concentrations for 30 minutes. The fabric was then removed and dried at 40°C. After it was completely dry, its radioactivity value (A2) was measured. The decontamination rate (DR) was calculated as follows:

[0103]

[0104] Uranium removal test on glass, metal, and ceramic surfaces: New experimental panels of different materials (glass, metal, and ceramic) measuring 10 cm × 10 cm were cleaned with deionized water and dried until the surface was completely dry. Before simulated contamination, a 5 cm × 5 cm square was drawn in the center of each panel. The natural background value (A0) of each panel was measured using an α / β surface contamination meter (RJ39-2060, Shanghai Ergonomic Testing Instrument Co., Ltd., Shanghai, China). 4 mL of a 4.75 g / L uranium solution was then poured into the drawn square on the panel to contaminate the panel. The panel was then oven-dried at 45°C. After the panel was completely dry, the radioactivity value (A1) was measured. A 0.2 mg / mL CPI-BT solution was prepared and sprayed onto the contaminated surface with the prepared CPI-BT detergent and water. The solution was allowed to stand for 30 minutes, the solution was recovered, and the panel was removed and oven-dried at 45°C. After the panel was completely dry, the radioactivity value (A2) was measured. The decontamination rate (DR) was calculated as follows:

[0105]

[0106] In order to expand the application range of CPI-BT, the UO2 2+ The removal effect was tested. The contaminated cotton fabric was cleaned with water and CPI-BT solution, and the UO2 after cleaning was measured. 2+ The amount removed was used to calculate the removal rate of CPI-BT on cotton fabrics, as shown in Figure 19 As shown in Figure A. The results showed that CPI-BT exhibited good removal efficiency for both α-U and β-U. When the CPI-BT dosage was 20 mg, the removal rates of α-U and β-U were 88.4% and 73.0%, respectively. As the amount of CPI-BT increased from 20 mg to 100 mg, α-DR and β-DR increased significantly. Among the different dosages of CPI-BT and the control, α-DR was relatively higher than β-DR.

[0107] CPI-BT solution was used to decontaminate simulated radionuclides on ceramic, glass and metal surfaces. Figure 19 As shown in BD. Due to the sufficient number of active chelating sites on CPI-BT, complexation with active functional groups, adsorption, and redox reactions facilitate the decontamination process. For all surfaces, α-DR and β-DR values ​​were significantly higher and >90%. Compared with water alone, the DR of ceramic, glass, and metal surfaces increased by 35.30%, 34.55%, and 11.16%, respectively. Compared with water alone, CPI-BT can effectively remove UO2 from different surfaces in a shorter time. 2+. Using wipes soaked in CPI-BT solution increased the α-DR and β-DR values ​​of all surfaces by >95%, but this increase was minimal compared to using CPI-BT solution alone. Since radioactive contaminants are mainly physically bound to the surfaces of these materials, the contaminants are easily dissolved in the CPI-BT solution detergent, making it easy to eliminate the simulated radionuclides. In addition, previous studies have shown that the wettability of the sample to the surface significantly improves its decontamination efficiency, because higher wettability means a greater chance of contact between the sample and the radionuclide. This further proves that CPI-BT is a viable option for decontamination of radioactively contaminated surfaces.

[0108] Example 4

[0109] In this example, the tannin-coupled cottonseed protein composite material obtained in Example 3 was modified, including:

[0110] Step 1: 1 g of the tannin-coupled cottonseed protein composite material prepared in Example 3 was added to 200 mL of a 70 wt% ethanol solution, 0.1 g of ferrous chloride and 0.1 g of polyethylene glycol-400 were added, the pH was adjusted to 3, and the mixture was stirred at 25° C. and 180 rpm for 3 h to obtain a mixed solution A;

[0111] Step 2: Add 0.2 g of tetrabutyl titanate and 0.1 g of citric acid to the mixed solution A, adjust the pH to 4, and stir at 45° C. and 180 rpm for 3 h to obtain a mixed solution B;

[0112] Step 3: Add 100 mL of 0.3 mol / L sodium borohydride solution to the mixed solution B, stir at 25° C. and 180 rpm for 2 h, and then centrifuge to collect the precipitate. After washing, freeze-dry at -80° C. for 48 h to obtain a modified tannin-coupled cottonseed protein composite material.

[0113] In this example, the obtained tannin-coupled cottonseed protein composite material was further modified by introducing zero-valent iron and titanium oxide, which have adsorption and reduction activity for uranyl ions. Polyethylene glycol-400 and citric acid were used as reaction aids to prevent agglomeration of the substances, improve dispersibility, and make the reaction more uniform and sufficient. The uranium removal ability of the modified tannin-coupled cottonseed protein composite material was further enhanced.

[0114] Example 5

[0115] In this example, the tannin-coupled cottonseed protein composite material obtained in Example 3 was modified, including:

[0116] Step 1: 1 g of the tannin-coupled cottonseed protein composite material prepared in Example 3 was added to 200 mL of a 70 wt% ethanol solution, 0.1 g of ferrous chloride and 0.1 g of polyethylene glycol-400 were added, the pH was adjusted to 3, and the mixture was stirred at 25° C. and 180 rpm for 3 h to obtain a mixed solution;

[0117] Step 2: add 100 mL of 0.3 mol / L sodium borohydride solution to the mixed solution, stir at 25° C. and 180 rpm for 2 h, then centrifuge to collect the precipitate, wash it, and freeze-dry it at −80° C. for 48 h to obtain a modified tannin-coupled cottonseed protein composite material.

[0118] Example 6

[0119] In this example, the tannin-coupled cottonseed protein composite material obtained in Example 3 was modified, including:

[0120] Step 1: 1 g of the tannin-coupled cottonseed protein composite material prepared in Example 3 was added to 200 mL of a 70 wt% ethanol solution, 0.2 g of tetrabutyl titanate and 0.1 g of citric acid were added, the pH was adjusted to 4, and the mixture was stirred at 45° C. and 180 rpm for 3 h to obtain a mixed solution;

[0121] Step 2: add 100 mL of 0.3 mol / L sodium borohydride solution to the mixed solution, stir at 25° C. and 180 rpm for 2 h, then centrifuge to collect the precipitate, wash it, and freeze-dry it at −80° C. for 48 h to obtain a modified tannin-coupled cottonseed protein composite material.

[0122] The tannin-coupled cottonseed protein composite materials prepared in Examples 4 to 6 were subjected to uranium removal tests in an aqueous environment, and the uranium removal rates RE obtained are shown in Table 3. It can be seen that the present invention further modifies the tannin-coupled cottonseed protein composite materials, and the uranium removal ability of the modified tannin-coupled cottonseed protein composite materials is further enhanced, with uranium removal rates exceeding 95%, with the highest being 98.0% in Example 4.

[0123] The tannin-coupled cottonseed protein composite materials prepared in Examples 4 to 6 were subjected to a test of their uranium purification performance on fabric materials, and the resulting stain removal rates DR are shown in Table 4. It can be seen that the tannin-coupled cottonseed protein composite materials prepared in Examples 4 to 6 had better stain removal rates for both α-U and β-U on cotton fabric materials than those in Example 3.

[0124] Table 3

[0125] Example 3 Example 4 Example 5 Example 6 Uranium removal rate RE (%) 93.8 98.0 96.5 97.2

[0126] Table 4

[0127] Example 3 Example 4 Example 5 Example 6 Detergency Ratio DR (α-U) (%) 88.4 93.3 90.2 91.5 Detergency Ratio DR (β-U) (%) 73.0 79.1 75.8 77.9

[0128] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing a tannin-coupled cottonseed protein composite material for uranium removal, characterized in that: The following steps are involved: Step 1: Add cottonseed protein to distilled water under a nitrogen atmosphere, stir, then add hydrogen peroxide solution and ascorbic acid, and continue stirring to obtain a cottonseed protein mixture; Step 2: adding plant tannins to the cottonseed protein mixture to make the concentration of plant tannins in the mixture be 0.3-1.1 mmol / L, stirring for reaction, dialyzing to remove unreacted plant tannins, and freeze-drying to obtain a tannin-coupled cottonseed protein composite material for uranium removal; Step 3: Modifying the prepared tannin-coupled cottonseed protein composite material, including: S1. Add the prepared tannin-coupled cottonseed protein composite material to a 50-80 wt% ethanol solution, then add ferrous chloride and polyethylene glycol-400, adjust the pH to 2-3, and stir at 20-30° C. and 100-200 rpm for 2-4 h to obtain a mixed solution A; S2. Add tetrabutyl titanate and citric acid to the mixed solution A, adjust the pH to 3-5, and stir at 40-50° C. and 100-200 rpm for 2-4 hours to obtain a mixed solution B; S3. Add 50-200 mL of 0.1-0.5 mol / L sodium borohydride solution to the mixed solution B, stir at 20-30° C. and 100-200 rpm for 1-3 h, collect the precipitate by centrifugation, wash it, and freeze-dry it to obtain a modified tannin-coupled cottonseed protein composite material for uranium removal; The tannin-coupled cottonseed protein composite material is used for removing uranium in a water environment.

2. The method for preparing a tannin-coupled cottonseed protein composite material for uranium removal according to claim 1, wherein: In the step 1, the mass volume ratio of cottonseed protein to distilled water is 1 g:50-150 mL.

3. The method for preparing a tannin-coupled cottonseed protein composite material for uranium removal according to claim 1, wherein: In the step 1, the stirring temperature is 20-30° C., and the stirring time is 1-3 h.

4. The method for preparing a tannin-coupled cottonseed protein composite material for uranium removal according to claim 1, wherein: In the step 1, the concentration of the hydrogen peroxide solution is 0.5-1.5 mol / L.

5. The method for preparing a tannin-coupled cottonseed protein composite material for uranium removal according to claim 1, wherein: In the step 1, the mass volume ratio of cottonseed protein to hydrogen peroxide solution is 1 g:1-5 mL; the mass ratio of cottonseed protein to ascorbic acid is 1:0.2-0.

7.

6. The method for preparing a tannin-coupled cottonseed protein composite material for uranium removal according to claim 1, wherein: In the step 2, the plant tannin is one or more of bayberry tannin, persimmon tannin, apple tannin, tea tannin and grape tannin.

7. The method for preparing a tannin-coupled cottonseed protein composite material for uranium removal according to claim 1, wherein: In the step 2, the stirring reaction temperature is 20-30° C. and the time is 20-30 h; and the freeze drying is freeze drying at -100--50° C. for 40-60 h.

8. Use of the tannin-coupled cottonseed protein composite material for uranium removal prepared by the preparation method according to any one of claims 1 to 7 in removing uranium from textile materials.

9. Use of a tannin-coupled cottonseed protein composite material for uranium removal prepared by the preparation method according to any one of claims 1 to 7 in removing uranium from glass, metal and ceramic surfaces.

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