CN113563633B

CN113563633B - Preparation and application of tannin polyphenol functionalized konjac glucomannan sponge for extracting uranium from seawater

Info

Publication number: CN113563633B
Application number: CN202110775907.5A
Authority: CN
Inventors: 竹文坤; 何嵘; 周莉; 杨帆; 陈涛; 雷佳; 任俨
Original assignee: Southwest University of Science and Technology
Current assignee: Southwest University of Science and Technology
Priority date: 2021-07-08
Filing date: 2021-07-08
Publication date: 2022-11-29
Anticipated expiration: 2041-07-08
Also published as: CN113563633A

Abstract

The invention discloses a preparation and application of a konjac glucomannan sponge functionalized by tannin polyphenol for extracting uranium from seawater, which comprises the following steps: obtaining KGM sponge by an ice template method; soaking KGM sponge in ethanol to obtain pretreated KGM sponge; adding tannic acid into a Tris-HCl solution, then adding a 3-aminopropyltriethoxysilane ethanol solution to obtain a mixed solution, then adding a pretreated KGM sponge into the mixed solution, reacting at room temperature, washing the reacted KGM sponge with deionized water, and drying in vacuum to obtain the tannin polyphenol functionalized konjac glucomannan sponge. The adsorption result of the enrichment and separation of uranium by adopting the tannin polyphenol functionalized konjac glucomannan sponge shows that the extraction rate in simulated seawater is up to more than 95%, the extraction rate can be effectively repeated and recycled, and the adsorption performance can still reach about 80% after 5 times of circulation.

Description

Preparation and application of tannin polyphenol functionalized konjac glucomannan sponge for extracting uranium from seawater

Technical Field

The invention relates to the technical field of uranium extraction from seawater, in particular to preparation and application of a konjac glucomannan sponge functionalized by tannin polyphenol for extracting uranium from seawater.

Background

With the global demand for energy and air pollution growing rapidly (partly from the production of fossil energy), nuclear energy is receiving widespread attention due to its non-greenhouse gas emissions and extremely high energy density. Uranium resources are essential resources for the development of the nuclear industry. The problem of uranium protection of nuclear fuels is increasingly prominent in the context of the rapid development of nuclear energy. In order to ensure the long-term development of nuclear energy, the development of unconventional uranium resources has important strategic significance. Seawater contains about 45 million tons of uranium, which is thousands of times the amount of uranium stored on land. If the uranium resources in seawater can be effectively enriched and extracted, uranium is an inexhaustible resource and is sufficient to ensure the sustainable development of human energy. Extraction of uranium from high salinity backgrounds is very challenging due to the low concentration of uranium in seawater and due to the large number of concurrent metal cations in seawater. Thus, efficient and selective extraction of uranium from seawater is a desirable choice for sustainable development of nuclear energy, but the challenge is enormous.

In order to efficiently extract uranium from seawater, various technologies have been greatly advanced, such as protein-based adsorbents, nanostructured materials (MOF, COF, POPs), grafted polymer adsorbents, metal oxides and phosphates, magnetic adsorbents, inorganic adsorbents, and biomass materials (fungal hyphae, chitosan). Cost analysis has shown that the performance and capacity of these adsorbents, including selectivity and recoverability, are insufficient for economically feasible uranium recovery compared to land mining. Therefore, there is an urgent need to develop a novel uranium extraction material that is economically feasible, environmentally friendly, highly selective, high in capacity and renewable. Due to the need to eliminate petrochemical derivatives and other hazardous precursors, the conversion of renewable biomass into valuable functional materials for energy production and environmental applications has attracted increasing attention. For commercialization and application, it is desirable to develop and design a sustainable process to produce uranium extraction material using large quantities of low cost precursors. In recent years, mussel biomimetic coatings represented by Polydopamine (PDA) have received wide attention in various fields such as water treatment due to their simple and mild preparation process, good adhesion, and good secondary reactivity. However, dopamine monomers used to prepare PDA are relatively expensive and not amenable to large scale production and use. Therefore, it is necessary to find a low cost alternative.

Disclosure of Invention

An object of the present invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.

To achieve these objects and other advantages in accordance with the purpose of the invention, there is provided a method for preparing a tannin polyphenol functionalized konjac glucomannan sponge for uranium extraction from seawater, comprising the steps of:

step one, adding 5-8 parts by mass of KGM into 180-220 parts by volume of water, stirring for 12 hours at room temperature to obtain KGM suspension, adding the KGM suspension into a mold, fixing the bottom of the mold on a steel plate, placing the steel plate in liquid nitrogen for freezing, and performing vacuum drying after complete freezing; adding the dried KGM into a high-temperature reaction kettle, simultaneously adding a mixed solution of 80-120 parts by volume of potassium hydroxide solution and 80-120 parts by volume of ethanol, and reacting for 10-15 h at 75-85 ℃; cooling to room temperature, washing with deionized water for 4 times every 24h, repeating for 3 times, and freeze-drying to obtain KGM sponge;

soaking KGM sponge in ethanol for 24 hours to obtain pretreated KGM sponge;

and step three, adding 0.2-0.7 part by mass of tannic acid into 80-120 parts by volume of Tris-HCl solution, then adding 18-23 parts by volume of 3-aminopropyltriethoxysilane ethanol solution to obtain a mixed solution, then adding the pretreated KGM sponge obtained in the step two into the mixed solution, reacting for 24 hours at room temperature, washing the reacted KGM sponge with deionized water, and drying in vacuum to obtain the tannin polyphenol functionalized konjac glucomannan sponge.

Preferably, in the first step, the concentration of the potassium hydroxide solution is 0.2 to 0.4mol/L.

Preferably, in the first step, the volume ratio of the potassium hydroxide solution to the ethanol is 1.

Preferably, in the second step, the preparation method of the 3-aminopropyltriethoxysilane ethanol solution is as follows: 0.8-1.2 volume parts of 3-aminopropyltriethoxysilane is dissolved in 18-24 volume parts of ethanol.

Preferably, the process in the second step is replaced by: adding KGM sponge into a high-pressure reaction kettle, adding methanol, introducing carbon dioxide to purge the high-pressure reaction kettle, heating the high-pressure reaction kettle to 40-45 ℃, injecting supercritical carbon dioxide, adjusting the pressure of the high-pressure reaction kettle to 10-12 MPa, reacting for 90-120 min, relieving pressure, washing with deionized water for 5 times, and freeze-drying to obtain the pretreated KGM sponge.

Preferably, the mass-to-volume ratio of the KGM sponge to the methanol is 1g; the mass ratio of the KGM sponge to the supercritical carbon dioxide is 1.

Preferably, the eluent is Na with the concentration of 0.5-1.5 mol/L ₂ CO ₃ And (3) solution.

The invention also provides application of the tannin polyphenol functionalized konjac glucomannan sponge for extracting uranium from seawater, which is characterized in that the tannin polyphenol functionalized konjac glucomannan sponge is added into seawater containing uranium, stirred and filtered, the tannin polyphenol functionalized konjac glucomannan sponge adsorbing uranium is placed into eluent, stirred and washed, and the seawater containing uranium is added again for cyclic utilization, so that enrichment and separation of the tannin polyphenol functionalized konjac glucomannan sponge on uranium are realized.

The invention at least comprises the following beneficial effects: the adsorption result of the konjac glucomannan sponge functionalized by the tannin polyphenol for extracting uranium from seawater shows that the extraction rate in simulated seawater is up to more than 95%, the sponge can be effectively repeated and reused, and the adsorption performance can still reach about 80% after 5 times of circulation. Therefore, the tannin polyphenol functionalized konjac glucomannan sponge has good application prospect for effectively extracting U (VI) at low cost.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Description of the drawings:

FIG. 1 is SEM images of KGM sponge obtained in step one (FIG. 1 a) and TA-APTES-KGM obtained in step three (FIGS. 1 b-c)) of example 1;

FIG. 2 is the Zeta potentials of the KGM sponge obtained in step one of example 1, the TA-APTES-KGM obtained in step three, and the TA-KGM prepared in comparative example 1;

FIG. 3 is a thermogravimetric plot of the KGM sponge obtained in step one, the TA-APTES-KGM obtained in step three, and the TA-KGM prepared in comparative example 1;

FIG. 4 is the water contact angle of the KGM sponge obtained in step one and the TA-APTES-KGM obtained in step three of example 1;

FIG. 5 is an XPS spectrum of KGM sponge obtained in step one and TA-APTES-KGM obtained in step three of example 1;

FIG. 6 is a C1s high resolution XPS spectrum of TA-APTES-KGM;

FIG. 7 is an infrared spectrum of KGM sponge obtained in step one, TA-APTES-KGM obtained in step three, and TA-KGM prepared in comparative example 1;

FIG. 8 is the effect of pH on U adsorption;

FIG. 9 is a graph of the effect of initial concentration on U adsorption;

FIG. 10 is the effect of solid-liquid ratio on U adsorption;

FIG. 11 is a graph of the effect of time on U adsorption;

FIG. 12 is a graph showing the effect of three coexisting ions on uranium adsorption capacity;

FIG. 13 is a graph of the effect of coexisting cations on uranium adsorption capacity;

FIG. 14 is a graph of the effect of coexisting anions on uranium adsorption capacity;

fig. 15 is a graph showing the adsorption capacity of the adsorbent in five adsorption-desorption cycles.

The specific implementation mode is as follows:

the present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.

It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.

Example 1:

a preparation method of a konjac glucomannan sponge for tannin polyphenol functionalization of uranium extraction from seawater comprises the following steps:

step one, adding 6g KGM into 200mL of deionized water, stirring for 12h at room temperature to obtain KGM suspension, adding the KGM suspension into a mold, fixing the bottom of the mold on a steel plate, placing the steel plate in liquid nitrogen for freezing, and performing vacuum drying after the steel plate is completely frozen; adding the dried KGM into a high-temperature reaction kettle, simultaneously adding 100mL of a 0.3M potassium hydroxide solution and 100mL of an ethanol mixed solution, and reacting for 12 hours at 80 ℃; cooling to room temperature, washing with deionized water for 4 times every 24h, repeating for 3 times, and freeze-drying to obtain KGM sponge;

soaking KGM sponge in ethanol for 24 hours to obtain pretreated KGM sponge;

step three, adding 0.5g of tannic acid into 100mL of Tris-HCl solution (pH = 8.5), then adding 3-aminopropyltriethoxysilane ethanol solution to obtain a mixed solution, then adding the pretreated KGM sponge obtained in the step two into the mixed solution, reacting for 24h at room temperature, washing the reacted KGM sponge with deionized water, and drying in vacuum to obtain the tannin polyphenol functionalized konjac glucomannan sponge, namely TA-APTES-KGM; the preparation method of the 3-aminopropyl triethoxysilane ethanol solution comprises the following steps: 1.05mL of 3-aminopropyltriethoxysilane was dissolved in 20mL of ethanol.

Example 2:

step one, adding 6g KGM into 200mL of deionized water, stirring for 12h at room temperature to obtain KGM suspension, adding the KGM suspension into a mold, fixing the bottom of the mold on a steel plate, placing the steel plate in liquid nitrogen for freezing, and performing vacuum drying after the steel plate is completely frozen; adding the dried KGM into a high-temperature reaction kettle, simultaneously adding 100mL of a 0.3M potassium hydroxide solution and 100mL of an ethanol mixed solution, and reacting for 12 hours at 80 ℃; cooling to room temperature, washing with deionized water for 4 times every 24h, repeating for 3 times, and freeze drying to obtain KGM sponge

Adding KGM sponge into a high-pressure reaction kettle, adding methanol, introducing carbon dioxide to purge the high-pressure reaction kettle, heating the high-pressure reaction kettle to 40 ℃, injecting supercritical carbon dioxide, adjusting the pressure of the high-pressure reaction kettle to 10MPa, reacting for 120min, relieving pressure, washing for 5 times by using deionized water, and freeze-drying to obtain pretreated KGM sponge; the mass volume ratio of the KGM sponge to the methanol is 1g; the mass ratio of the KGM sponge to the supercritical carbon dioxide is 1;

step three, adding 0.5g of tannic acid into 100mL of Tris-HCl solution (pH = 8.5), then adding 3-aminopropyltriethoxysilane ethanol solution to obtain a mixed solution, then adding the pretreated KGM sponge obtained in the step two into the mixed solution, reacting for 24h at room temperature, washing the reacted KGM sponge with deionized water, and drying in vacuum to obtain the tannin polyphenol functionalized konjac glucomannan sponge; namely TA-APTES-KGM-1; the preparation method of the 3-aminopropyl triethoxysilane ethanol solution comprises the following steps: 1.05mL of 3-aminopropyltriethoxysilane was dissolved in 20mL of ethanol.

Comparative example 1:

a preparation method of tannin polyphenol functionalized konjac glucomannan sponge for extracting uranium from seawater comprises the following steps:

step one, adding 6g KGM into 200mL of deionized water, stirring for 12h at room temperature to obtain KGM suspension, adding the KGM suspension into a mold, fixing the bottom of the mold on a steel plate, placing the steel plate in liquid nitrogen for freezing, and performing vacuum drying after the steel plate is completely frozen; adding the dried KGM into a high-temperature reaction kettle, simultaneously adding 100mL of a 0.3M potassium hydroxide solution and 100mL of an ethanol mixed solution, and reacting for 12 hours at 80 ℃; cooling to room temperature, washing with deionized water every 24h for 4 times, repeating for 3 times, and freeze-drying to obtain KGM sponge;

soaking KGM sponge in ethanol for 24 hours to obtain pretreated KGM sponge;

step three, adding 0.5g of tannic acid into 100mL of Tris-HCl solution (pH = 8.5), then adding the pretreated KGM sponge obtained in the step two into the mixed solution, reacting at room temperature for 24h, washing the reacted KGM sponge with deionized water, and drying in vacuum to obtain the tannin polyphenol functionalized konjac glucomannan sponge; i.e., TA-KGM.

FIG. 1 is an SEM image of KGM sponge obtained in step one (FIG. 1 a) and an SEM image of TA-APTES-KGM obtained in step three (FIGS. 1 b-c)); the surface of the KGM sponge is smooth. For TA-APTES-KGM, the surface becomes rough and many nanospheres are decorated on the KGM. These nanospheres are formed by a combination of covalent bonds, hydrogen bonds, pi-pi interactions, and interchain physical cross-links. Since a large number of nanospheres are exposed on the surface and contain phenolic hydroxyl groups, U (VI) can be efficiently extracted.

FIG. 2 shows Zeta potentials of KGM sponge obtained in step one, TA-APTES-KGM obtained in step three, and TA-KGM prepared in comparative example 1. The Zeta potential values of KGM and TA-KGM are comparable, but at different pH values are much higher than those of TA-APTES-KGM. In addition, the Zeta potential of TA-APTES-KGM was about-25 eV at pH8, indicating that the TA-APTES-KGM surface is covered with a lot of negative charges. A negative potential value may favor the adsorption of U (VI).

FIG. 3 shows thermogravimetric curves of KGM sponge obtained in step one of example 1, TA-APTES-KGM obtained in step three, and TA-KGM prepared in comparative example 1, wherein the weight loss process of the sample can be roughly divided into two steps. The first weight loss occurred at about 10% at 100c due to the release of physisorbed water. The second weight loss, about 67%, occurs at 200-450 c due to decomposition of the oxygen-containing functional groups. The weight loss process of TA-KGM is similar to KGM. It can be concluded that the thermal decomposition of TA-PATES-KGM is at 200-450 ℃. Therefore, the amount of CTA-APTES in TA-APTES-KGM is about 0.92%.

FIG. 4 is the water contact angle of KGM sponge obtained in step one and TA-APTES-KGM obtained in step three of example 1, the key parameter affecting uranium extraction capacity and kinetics being the hydrophilicity of the adsorbent. As a hydrophilic material, the water contact angle of KGM reached 62.9 ℃ after 1s contact with a water drop. As shown in fig. 4, the presence of the TA-APTES coating significantly reduced the contact angle of the KGM. After contacting with water, the contact angle of TA-APTES-KGM rapidly decreases and reaches 48.6 degrees within 0.4 seconds after contacting, indicating that the modified material has high hydrophilicity.

FIG. 5 shows XPS spectra of KGM sponge obtained in step one and TA-APTES-KGM obtained in step three of example 1. Broad scanning XPS spectra of KGM and TA-APTES-KGM showed peaks of 531.08eV and 285.08eV for O1s and C1s, respectively. Compared with the spectrum of KGM, TA-APTES-KGM shows new nitrogen peaks (399 eV) and Si2p (100 eV), which are attributed to APTES.

FIG. 6 is a C1s high resolution XPS spectrum of TA-APTES-KGM with the C1s spectrum at the four peaks at 288.1eV,286.6eV,285.3eV and 284.6eV, respectively, corresponding to the C = O, C-OH, C-C and C = C bonds, respectively. The C = O groups on the functional coating should be derived from quinones produced by oxidation of the TA molecule, while the-OH groups should be attributed to residual phenolic hydroxyl groups of the TA molecule and to hydrolysate molecules of APTES.

FIG. 7 is an infrared spectrum of KGM sponge obtained in step one, TA-APTES-KGM obtained in step three, and TA-KGM prepared in comparative example 1; for KGM sponge, at 3434.24cm ^-1 The absorption peak at (A) was assigned to the tensile vibration of the-OH bond, and 1049.81cm ^-1 、1631.48cm ^-1 And 2919.44cm ^-1 Respectively due to C ₆ -OH, C-O and C-H. It can be noted that the FT-IR spectrum of KGM is similar to that of TA-KGM. Compared to KGM, there is no new absorption band in TA-KGM, indicating that no new chemical peak is formed between TA and KGM. For TA-APTES-KGM, 3400-3100cm can be observed ^-1 A broad peak at (a), which corresponds to O-H vibration. At the same time, 1430.80 cm ^-1 And 1374.66cm ^-1 The new adsorption band at (A) is due to the phenolic hydroxyl group n (C-OH). These results demonstrate the successful grafting of TA to KGM.

Uranium adsorption experiment:

5mg of KGM sponge (prepared as step one of example 1), TA-APTES-KGM (prepared as described in example 1), TA-APTES-KGM-1 (prepared as described in example 2) and TA-KGM (prepared as described in comparative example 1) were added to a solution containing 20mL of UO at a concentration of 8ppm ₂ ²⁺ In a solution flask, adjusting the pH value to a required value by 0.01mol/L HCl or NaOH, and filtering the solution by a 0.22 mu m filter after stirring and adsorption at 30 ℃; and measured by ICPMeasuring the concentration of U (VI) in the solution before and after adsorption;

adsorption amount of uranium (q) _e Mg/g) and Extraction efficiency (Extraction efficiency,%) were calculated by the following formulas:

q _e ＝(C ₀ -C _e )V/m

Extraction efficiency＝(C ₀ -C _t )/C ₀ ×100％；

wherein C ₀ (mg/mL) represents UO in the initial solution ₂ ²⁺ Concentration of (C) _e (mg/mL) is the equilibrium solution concentration, V (mL) represents the solution volume, and m (g) is the amount of adsorbent used.

TA-APTES-KGM, TA-APTES-KGM-1 and TA-KGM were added to 20mL of the solution (uranium concentration: 8 ppm), respectively, and the effect of the pH of the solution in the range of 2 to 10 on the extraction performance of uranium was investigated (FIG. 8). The extractability depends on the pH of the U (VI) solution. At pH 2-5, the adsorption capacity is significantly improved, and at pH 6-8, the adsorption capacity is only slightly reduced. The TA-APTES-KGM and TA-APTES-KGM-1 still have high extraction efficiency at the pH value of 8 (belonging to the pH range of real seawater), which indicates that the TA-APTSE-KGM and the TA-APTES-KGM-1 are suitable for absorbing uranium from natural seawater. The effect of pH on extractability may be attributed to the species distribution of uranium and the surface charge of the material. Negatively charged materials and with UO ₂ ²⁺ ，UO ₂ (OH) ⁺ ，(UO ₂ ) ₂ (OH) ₂ ²⁺ Electrostatic repulsion between the cationic uranium species present in the form results in higher extraction capacity under acidic conditions. However, in an alkaline environment, the species of the anion uranium increases and becomes the predominant form of uranium present, thereby reducing extraction efficiency. In the following experiments to test the extraction efficiency, a pH of 5 was chosen to prevent precipitation of uranium.

Further analysis is carried out on the extraction efficiency in order to further understand the extraction process; FIG. 9 illustrates the effect of initial U (VI) concentration on the U (VI) extraction efficiency of TA-APTES-KGM. Adding 5mg of adsorbent (TA-APTES-KGM) into 20mL of solution (the concentration of U (VI): 1-8 mg/L), and adjusting the pH value to 5; stirring for 150min at 30 ℃; as shown in FIG. 9, TA-APTES-KGM maintained high extraction rates over a wide range of U (VI) concentrations. The results show that the average extraction rate is as high as 97% under the U (VI) concentration of 1-8 mg/L.

In addition, as shown in FIG. 10, the maximum extraction rate of TA-APTES-KGM reached 96% as the solid-to-liquid ratio (5 mg of adsorbent added to different volumes of U (VI) solution) increased when the initial U (VI) concentration was 8 mg/L.

In addition, the influence of time on the adsorption of U (VI) was considered. Adding 5mg adsorbent (TA-APTES-KGM) into 20mL solution (U (VI) concentration: 8 mg/L), and adjusting pH to 5; stirring at different temperatures; as can be seen from fig. 11, the absorption rate was quite fast and the adsorption equilibrium was reached within 100min, indicating that bulk adsorption occurred during convective mass transfer on the TA-APTES-KGM surface, during mass transfer without diffusive mass transfer in the pore structure. Due to the temperature dependence and considerable adsorption kinetics, it can be reasonably concluded that the extraction of uranium occurs mainly by the formation of supramolecular structures on the microstructure of TA-APTSE-KGM.

Influence of competing ions:

ion selectivity tests were performed on the U (VI) solution to detect the presence of different interfering ions. Thus, ca ² ⁺ ，K ⁺ ，Mg ²⁺ ，Cu ²⁺ ，Na ⁺ ，Zn ²⁺ ，Pb ²⁺ ，Sr ²⁺ ，HCO ₃ ^- ，Br ^- And SO ₄ ² Is 10 times the concentration of the 8ppm U (VI) solution. 5mg of adsorbent (TA-APTSE-KGM) was placed in 20mL of the solution and the adsorption was carried out at a temperature of 303K.

Usually, various metal ions, such as Na, are found in seawater at the same time ⁺ ，Ca ²⁺ ，Mg ²⁺ And anions such as Cl ^- ，NO ₃ ^- ，HCO ₃ ^- However, these competing ions had little effect on the extraction rate of uranium (fig. 12). These data indicate that TA-APTES-KGM has a very high selectivity for uranium extraction. In addition, higher performance can be achieved by increasing the density of TA adsorption sites. To evaluate the potential practical application of TA-APTES-KGM in uranium extraction from seawater, simulated seawater containing various competing ionsA comprehensive uranium extraction experiment was performed. TA-APTES-KGM even in the presence of excess competing ions (including Ca) ²⁺ ， K ⁺ ，Mg ²⁺ ，Cu ² ⁺ ，Na ⁺ ，Zn ²⁺ ，Pb ²⁺ ，Sr ²⁺ ，HCO ₃ ^- ，Br ^- SO ₄ ² And C ^l- ) Also shows a stable uranium extraction efficiency in the presence of (fig. 13 and 14). The high selective extraction capacity of TA-APTES-KGM may be due to the lower steric hindrance of the phenolic hydroxyl group when complexed with the large ionic radius of uranium species. In addition, the special electronic configuration and high valence state of the uranium ions enable good interaction with the electron pairs provided by the phenolic hydroxyl groups.

Elution and reusability:

preparation of Na ₂ CO ₃ Solution (1M) was the eluent. After each cycle, the adsorbents (TA-APTES-KGM and TA-APTES-KGM-1) were placed in an excess of the eluent and stirred at a temperature of 303K for 2h. In addition, the adsorbent was washed 3 times with deionized water and freeze dried to ensure that the uranium was completely eluted.

The reusability of TA-APTES-KGM and TA-APTES-KGM-1 was investigated by eluting the bound uranium and performing adsorption-desorption experiments. Thus, the eluent (1M Na) was used ₂ CO ₃ ) And (3) eluting uranium adsorbed on the TA-APTES-KGM and the TA-APTES-KGM-1, wherein the material is slightly damaged in the reaction process due to high elution efficiency. The adsorption of uranium was carried out in 20mL of simulated seawater under a condition of U (VI) concentration of 8ppm at pH5 (5 mg of adsorbent), and the reaction was carried out for 24 hours. The extraction efficiency of uranium gradually decreased in each cycle, and after five cycles of repeated use, the extraction efficiency of uranium by TA-APTES-KGM was still about 75% (fig. 14). The uranium extraction efficiency of TA-APTES-KGM-1 was still about 80% (fig. 15), and the results show that higher efficiency can still be maintained in the simulated seawater extraction process.

While embodiments of the invention have been described above, it is not intended to be limited to the details shown, described and illustrated herein, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed, and to such extent that such modifications are readily available to those skilled in the art, and it is not intended to be limited to the details shown and described herein without departing from the general concept as defined by the appended claims and their equivalents.

Claims

1. A preparation method of a konjac glucomannan sponge functionalized by tannin polyphenol for extracting uranium from seawater is characterized by comprising the following steps:

step one, adding 5 to 8 parts by mass of KGM into 180 to 220 parts by volume of water, stirring for 12 hours at room temperature to obtain KGM suspension, adding the KGM suspension into a mold, fixing the bottom of the mold on a steel plate, placing the steel plate in liquid nitrogen for freezing, and after completely freezing, carrying out vacuum drying; adding the dried KGM into a high-temperature reaction kettle, simultaneously adding a mixed solution of 80-120 parts by volume of a potassium hydroxide solution and 80-120 parts by volume of ethanol, and reacting for 10-15h at 75-85 ℃; cooling to room temperature, washing with deionized water for 4 times every 24h, repeating for 3 times, and freeze-drying to obtain KGM sponge;

soaking KGM sponge in ethanol for 24 hours to obtain pretreated KGM sponge;

and step three, adding 0.2 to 0.7 mass part of tannic acid into 80 to 120 volume parts of Tris-HCl solution, then adding 18 to 23 volume parts of 3-aminopropyltriethoxysilane ethanol solution to obtain a mixed solution, then adding the pretreated KGM sponge obtained in the step two into the mixed solution, reacting for 24 hours at room temperature, washing the reacted KGM sponge with deionized water, and carrying out vacuum drying to obtain the tannin polyphenol functionalized konjac glucomannan sponge.

2. The method for preparing the konjac glucomannan sponge functionalized by the tannin polyphenol for extracting uranium from seawater as claimed in claim 1, wherein in the first step, the concentration of the potassium hydroxide solution is 0.2 to 0.4mol/L.

3. The method for preparing a tannin polyphenol functionalized konjac glucomannan sponge for uranium extraction from sea water as claimed in claim 1, wherein in the first step, the volume ratio of the potassium hydroxide solution to the ethanol is 1.

4. The method for preparing the tannin polyphenol functionalized konjac glucomannan sponge for uranium extraction from seawater as claimed in claim 1, wherein in the third step, the preparation method of the 3-aminopropyltriethoxysilane ethanol solution is as follows: dissolving 0.8 to 1.2 volume parts of 3-aminopropyltriethoxysilane in 18 to 24 volume parts of ethanol.

5. The method for preparing the konjac glucomannan sponge functionalized with tannin polyphenols for extracting uranium from seawater as claimed in claim 1, wherein the process in the second step is replaced by: adding KGM sponge into a high-pressure reaction kettle, adding methanol, introducing carbon dioxide to purge the high-pressure reaction kettle, heating the high-pressure reaction kettle to 40-45 ℃, then injecting supercritical carbon dioxide, adjusting the pressure of the high-pressure reaction kettle to 10-12MPa, reacting for 90-120min, relieving pressure, washing for 5 times by using deionized water, and freeze-drying to obtain the pretreated KGM sponge.

6. The method for preparing a konjac glucomannan sponge functionalized by tannin polyphenols for uranium extraction from seawater as claimed in claim 5, wherein the mass volume ratio of KGM sponge to methanol is 1g; the mass ratio of the KGM sponge to the supercritical carbon dioxide is 1.

7. The application of the tannin polyphenol functionalized konjac glucomannan sponge for extracting uranium from seawater prepared by the preparation method of any one of claims 1 to 6 in extracting uranium from seawater is characterized in that the tannin polyphenol functionalized konjac glucomannan sponge is added into seawater containing uranium, stirred and filtered, the tannin polyphenol functionalized konjac glucomannan sponge adsorbed with uranium is placed into eluent, stirred and washed, and the seawater containing uranium is added again for cyclic utilization, so that the enrichment and separation of the tannin polyphenol functionalized konjac glucomannan sponge on uranium are realized.

8. Konjac glucomannan functionalized with tannin polyphenols for uranium extraction from seawater according to claim 7The application of the sponge in uranium extraction from seawater is characterized in that the eluent is Na with the concentration of 0.5 to 1.5mol/L ₂ CO ₃ And (3) solution.