AU2020103503A4

AU2020103503A4 - Boric acid adsorbent material and preparation method

Info

Publication number: AU2020103503A4
Application number: AU2020103503A
Authority: AU
Inventors: Zihao HU; Ren JING; Fangong KONG; Nannan XIA; Huiya ZHANG
Original assignee: Qilu University of Technology
Current assignee: Qilu University of Technology
Priority date: 2020-03-19
Filing date: 2020-11-18
Publication date: 2021-01-28
Anticipated expiration: 2028-11-18
Also published as: CN111359594A; CN111359594B

Abstract

The present disclosure discloses a boric acid adsorbent material, including the following components: 1-5 parts by weight of tannic acid, 1-5 parts by weight of lignosulfonate, and 0.05 0.5 parts by weight of cationic polymer. In the present disclosure, using biomass material lignin as a carrier, tannic acid as an adsorptive functional monomer, and cationic polymer as an intermediate, three raw materials are cross-linked together in a self-assembly mode to prepare a bio-based boric acid adsorbent material. The adsorbent material has a certain nanopore structure; under the alkaline condition, boric acid in the surrounding environment flows into the pore structure to be in contact with catechol on the surface of tea polyphenol in the material, so that a borate is produced and the purpose of adsorbing boric acid is achieved; under the acidic condition, the borate can be dissociated, so that the purposes of adsorbing/desorbing and effectively separating boric acid are achieved. 1/1 OH OH OH HO NOH OH OH / 1___ [ ~ B + 2H20 FIG. 1 FIG. 2 Add tannic acid Boric acid solution FIG. 3

Description

1/1 OH OH

OH HO NOH / 1___ [ ~ OH B OH +2H20

FIG. 1

FIG. 2

Add tannic acid

Boric acid solution

FIG. 3

BORIC ACID ADSORBENT MATERIAL AND PREPARATION METHOD TECHNICAL FIELD

The present disclosure relates to a boric acid adsorbent material and a preparation method.

BACKGROUND

In recent years, with the pollution of freshwater resources and the increasing demand for freshwater resources by humans, seawater desalination has become one of the important measures to solve the above problems. During seawater desalination, desalination rate is an important indicator. The methods mainly include freezing method, electrodialysis method, distillation method, reverse osmosis method and ion exchange method, etc. Through the single or mixed use of the above methods, the majority of bivalent salts can be removed from the seawater. However, due to the low concentration of boric acid in seawater and small molecular diameter thereof, it is difficult to reduce to the 0.5 mg/L, a requirement of the Standardsfor Drinking Water Quality, through the above method; moreover, appropriate boric acid is beneficial to plant growth and human health. Therefore, removing and recycling excess boric acid during seawater desalination is an important way to meet seawater desalination and human needs at the same time.

Boric acid is a weak acid and has an acidity coefficient PKa of 9.24 at 25°C. In an alkaline marine environment greater than pH 8.0, the boric acid usually binds to the hydroxyl of water and exists in the form of B(OH) 4. In existing research reports, the most effective method for removing boric acid is mainly adsorption method. The adsorption method is an adsorptive separation method that uses a porous solid adsorbent with a large specific surface area to adsorb one or more components in the solution on the surface of or in micropores of the adsorbent. The method mainly includes physical adsorption, chemical adsorption, or a combination of both. Obviously, because the physical adsorption method attracts an adsorbate through the Van der Waals force between the adsorbent and the adsorbate, there is a disadvantage of low adsorption selectivity. Therefore, the method cannot meet the requirements of seawater desalination for boron removal and recovery; the chemical adsorption method is to fix the adsorbate on the surface of the adsorbent through a chemical reaction between the adsorbate and the adsorbent, so the adsorption selectivity is high, and further, the method can achieve both adsorption and recovery purposes by separating the adsorbate in a certain manner. At present, a more effective method for the separation and recovery of boric acid by chemical adsorption is to esterify with o-hydroxyl groups on the surface of the adsorbent in the form of boric acid in alkaline seawater, and dissociate the boric acid through acid adjustment, so as to achieve the purpose of recycling.

Framework materials include cyclodextrin, biomass carbon aerogel, tannic acid gel, modified activated carbon, polyacrylonitrile nanofiber or membrane, organic nanomaterials, etc. The adsorption capacity of the above adsorbents for boric acid can be up to 35.1 mg/g. However, the above-mentioned adsorbents have relatively complicated synthesis processes, and it is difficult to meet the requirements of large-scale seawater desalination. In addition, during the preparation process of the adsorbent, purification and separation processes may cause secondary pollution to the environment. Therefore, a higher requirement is proposed for adsorbent materials for seawater desalination.

SUMMARY

The present disclosure overcomes at least one defect (deficiency) described in the prior art.

To solve the above technical problems, a primary objective of the present disclosure is to provide a boric acid adsorbent material, raw materials of which include the following components:

1-5 parts by weight of tannic acid, 1-5 parts by weight of lignosulfonate, and 0.05-0.5 parts by weight of cationic polymer.

Preferably, the cationic polymer may be a compound with a positive charge on the surface.

Preferably, the cationic polymer may be cationic polyacrylamide or chitosan.

Preferably, the cationic polyacrylamide may be dissolved in a 4% ethanol aqueous solution with a concentration of 2%o.

Preferably, the chitosan may be dissolved in a 5% acetic acid aqueous solution with a concentration of 1.6%.

Preferably, the amount of tannic acid, lignosulfonate and cationic polymer may be on an absolute dry basis.

Another objective of the present disclosure is to provide a method for preparing the foregoing boric acid adsorbent material, including the following steps:

Si. dissolving tannic acid and lignosulfonate in distilled water separately, mixing after dissolving completely, and stirring until uniform;

S2. adding a cationic polymer solution to a mixed solution, and stirring until a mass of flocculent substances appear and no longer increase;

S3. letting the mixed solution stand for 2 h;

S4. removing a supernatant, and centrifuging precipitates for 5 min at 5,000 r/min;

S5. removing a supernatant, and washing precipitates thrice with water; and

S6. conducting vacuum freeze-drying for 48 h.

Preferably, mixing temperature may be 25°C.

Preferably, the cationic polymer solution may be a cationic polyacrylamide solution.

Preferably, the cationic polymer solution may be added dropwise.

Compared with the prior art, the technical solutions of the present disclosure have the following beneficial effects:

1. Adsorption of boric acid by existing adsorbents is mainly aimed at high-concentration adsorption, and the adsorbent material per se and the preparation process do not meet the requirements of environmental protection. The present disclosure uses biomass resources as matrix materials and water as a reaction solvent or dispersant in the preparation process, effectively solving the above problem.

2. According to the concentration range of boric acid in seawater, the present disclosure achieves the purpose of effectively adsorbing low-concentration boric acid.

3. Among many biomass resources, because the catechol structure in tannic acid can react with boric acid under alkaline conditions to produce a borate, tannic acid can be used as a functional monomer for boric acid adsorption (FIG. 1); however, a single tannic acid is difficult to be separated from water after absorbing boric acid, so tannic acid cannot meet the comprehensive requirements for boric acid adsorbent materials during seawater desalination. Since lignin is a biopolymer with a three-dimensional network structure formed by three phenylpropane units connected to each other through ether bonds and carbon-carbon bonds, lignin and tannic acid have negative charges on the surface. Therefore, if a cationic polymer is used to bind the three together by electrostatic action, under the condition that tannic acid is used as an adsorptive functional monomer, lignin as a carrier not only makes the polymer achieve a purpose of higher boric acid adsorption, but also achieves effective separation and recycling after adsorption.

4. In the present disclosure, using biomass material lignin as a carrier, tannic acid as an adsorptive functional monomer, and cationic polymer as an intermediate, three raw materials are

cross-linked together in a self-assembly manner to prepare a bio-based boric acid adsorbent material. The adsorbent material has a certain nanopore structure; under the alkaline condition, boric acid in the surrounding environment flows into the pore structure to be in contact with catechol on the surface of tea polyphenol in the material, so that a borate is produced and the purpose of adsorbing boric acid is achieved; under the acidic condition, the borate can be dissociated, so that the purposes of adsorbing/desorbing and effectively separating boric acid are achieved.

5. The lignosulfonate used in the present disclosure is a kind of biomass resource, which is cheap and renewable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an adsorption mechanism of boric acid by catechol.

FIG. 2 is a scanning electron micrograph of a bio-based boric acid adsorbent material.

FIG. 3 shows the adsorption of boric acid by tannic acid alone.

DETAILED DESCRIPTION

Commercially available products are used in the present disclosure. The present disclosure will be described in detail below.

The present disclosure provides a boric acid adsorbent material, raw materials of which include the following components:

As an improvement of the specific embodiment, the cationic polymer may be a compound with a positive charge on the surface.

As an improvement of the specific embodiment, the cationic polymer may be cationic polyacrylamide or chitosan.

As an improvement of the specific embodiment, the cationic polyacrylamide may be dissolved in a 4% ethanol aqueous solution with a concentration of 2%o.

As an improvement of the specific embodiment, the chitosan may be dissolved in a 5% acetic acid aqueous solution with a concentration of 1.6%.

As an improvement of the specific embodiment, the amount of tannic acid, lignosulfonate and cationic polymer may be on an absolute dry basis.

The present disclosure further provides a method for preparing the foregoing boric acid adsorbent material, including the following steps:

S. dissolving tannic acid and lignosulfonate in distilled water separately, mixing after dissolving completely, and stirring until uniform;

S3. letting the mixed solution stand for 2 h;

S5. removing a supernatant, and washing precipitates thrice with water; and

S6. conducting vacuum freeze-drying for 48 h.

As an improvement of the specific embodiment, mixing temperature may be 250 C

As an improvement of the specific embodiment, the cationic polymer solution may be a cationic polyacrylamide solution.

As an improvement of the specific embodiment, the cationic polymer solution may be added dropwise.

A certain amount of tannic acid and lignosulfonate are dissolved in distilled water separately, stirred evenly at 25 0 C until lignin and tannic acid completely dissolved separately, so as to prepare solutions with a given mass concentration; both solutions are mixed and stirred evenly under mechanical stirring; a cationic polyacrylamide solution is added dropwise to the foregoing mixed solution and stirred constantly until flocculent substances gradually appear in the mixed solution and no longer increase. Product precipitates are let stand for 2 h, a supernatant is removed; the precipitates are centrifuged for 5 min at 5,000 r/min; a supernatant is removed sequentially, and precipitates are repeatedly washed with water thrice and subjected to vacuum freeze-drying for 48 h to obtain a final product, i.e., a bio-based boric acid adsorbent material. The cationic polymer may principally be cationic polyacrylamide, or chitosan and other compounds with positive charges on the surface. The cationic polyacrylamide contains a large amount of quaternary ammonium salt, which shows a positive charge per se, while the chitosan contains a large number of amine groups, which dissolve in an aqueous solution and receive protons, thereby showing a positive charge. The cationic polyacrylamide or the chitosan must be dissolved before use. The cationic polyacrylamide is dissolved in 4% ethanol aqueous solution, and the chitosan is dissolved in 5% acetic acid aqueous solution, where the concentration of cationic polyacrylamide is 2 %o, and the concentration of chitosan is 1.6%. Separately, the on an absolute dry basis of tannic acid, lignosulfonate and cationic polymer is:

1-5 parts by weight of tannic acid;

1-5 parts by weight of lignosulfonate; and

0.05-0.5 parts by weight of cationic polyacrylamide or chitosan.

The tannic acid, the lignosulfonate and the cationic polyacrylamide may be stirred at a rate of 200-500 r/min.

Through the electrostatic interaction among tannic acid, lignosulfonate and cationic polymer, these raw materials are assembled in aqueous solution to produce a bio-based composite boric acid adsorbent material with a certain pore structure, which contains a large amount of catechol structures. After immersing the material in a boric acid solution, boric acid impregnates into the material and binds to catechol to form borate. At this time, adsorption will promote the internal expansion of the material and expose more catechol structures. These structures increase the chance to contact with boric acid, so as to achieve the purpose of efficient adsorption. FIG. 2 shows lignin (top left), cationic polyacrylamide (top right), tannic acid (bottom left) and assembled bio-based materials (bottom right), where a white line represents 200 nm. It can be clearly observed from the figure that there is no obvious pore structure on the surface of lignin, cationic polyacrylamide and tannic acid, but after assembly, an obvious nanoporous structure is formed; an orderly assembly process can be formed between negative charges in lignin and tannic acid and positive charges in the cationic polyacrylamide, and a large number of nanoporous structures are assembled. The boric acid adsorbent material prepared by the present disclosure not only overcomes the defects of complex synthesis process of the existing boric acid adsorbent materials, low adsorption capacity, low removal amount of low-concentration boric acid, and difficulty in meeting the requirements of large-scale seawater desalination, but also provides a new approach for the development and utilization of biomass resources.

Specific embodiments

Cationic polyacrylamide was prepared with 4% ethanol solution into a solution with a mass concentration of 2%o, and chitosan was prepared with a 5% acetic acid solution into a solution with a mass concentration of 1.6%, which was used for the bio-based boric acid adsorbent material preparation.

Embodiment 1

2 g of cationic polyacrylamide with a molecular weight of 200,000 was slowly dissolved in 1,000 mL of 4% ethanol solution at a rotation speed of 200 r/min to obtain a cationic polyacrylamide solution with a mass concentration of 2%o for use.

1 g of tannic acid and 1 g of lignosulfonate were dissolved in 200 mL of distilled water separately, and stirred evenly at 25°C until lignin and tannic acid were completely dissolved separately, and both of them were mixed well; a mixed solution was stirred mechanically and evenly at 200 r/min; 0.05 g of well-prepared cationic polyacrylamide was added dropwise to the foregoing mixed solution and constantly stirred at this speed for 2 h. Product precipitates were let stand for 2 h, and a supernatant was removed; precipitates were centrifuged for 5 min at 5,000 r/min, and a supernatant was removed sequentially; the precipitates were repeatedly washed with water thrice, and subjected to vacuum freeze-drying for 48 h to obtain a final product, i.e., a bio based boric acid adsorbent material.

Embodiment 2

2 g of cationic polyacrylamide with a molecular weight of 2,000,000 was slowly dissolved in 1,000 mL of 4% ethanol solution at a rotation speed of 200 r/min to obtain a cationic polyacrylamide solution with a mass concentration of 2%o for use.

2 g of tannic acid and 10 g of lignosulfonate were dissolved in 200 mL of distilled water separately, and stirred evenly at 25°C until lignin and tannic acid were completely dissolved separately, and both of them were mixed well; a mixed solution was stirred mechanically and evenly at 300 r/min; 0.5 g of well-prepared cationic polyacrylamide was added dropwise to the foregoing mixed solution and constantly stirred at this speed for 2 h. Product precipitates were let stand for 2 h, and a supernatant was removed; precipitates were centrifuged for 5 min at 5,000 r/min, and a supernatant was removed sequentially; the precipitates were repeatedly washed with water thrice, and subjected to vacuum freeze-drying for 48 h to obtain a final product, i.e., a bio based boric acid adsorbent material.

Embodiment 3

16 g of chitosan with a deacetylation degree of 95% was slowly dissolved in 1,000 mL of ethanol solution with a mass concentration of 5% at a rotation speed of 200 r/min to obtain a chitosan solution with a mass concentration of 1.6% for use.

10 g of tannic acid and 2 g of lignosulfonate were dissolved in 200 mL of distilled water separately, and stirred evenly at 25°C until lignin and tannic acid were completely dissolved separately, and both of them were mixed well; a mixed solution was stirred mechanically and evenly at 500 r/min; 0.3g of well-prepared chitosan was added dropwise to the foregoing mixed solution and constantly stirred at this speed for 2 h. Product precipitates were let stand for 2 h, and a supernatant was removed; precipitates were centrifuged for 5 min at 5,000 r/min, and a supernatant was removed sequentially; the precipitates were repeatedly washed with water thrice, and subjected to vacuum freeze-drying for 48 h to obtain a final product, i.e., a bio-based boric acid adsorbent material.

Embodiment 4

As shown in Embodiment 3, 16 g of chitosan with a deacetylation degree of 95% was slowly dissolved in 1,000 mL of ethanol solution with a mass concentration of 5% at a rotation speed of 200 r/min to obtain a chitosan solution with a mass concentration of 1.6% for use.

3 g of tannic acid and 3 g of lignosulfonate were dissolved in 200 mL of distilled water separately, and stirred evenly at 25°C until lignin and tannic acid were completely dissolved separately, and both of them were mixed well; a mixed solution was stirred mechanically and evenly at 400 r/min; 0.4 g of well-prepared chitosan was added dropwise to the foregoing mixed solution and constantly stirred at this speed for 2 h. Product precipitates were let stand for 2 h, and a supernatant was removed; precipitates were centrifuged for 5 min at 5,000 r/min, and a supernatant was removed sequentially; the precipitates were repeatedly washed with water thrice, and subjected to vacuum freeze-drying for 48 h to obtain a final product, i.e., a bio-based boric acid adsorbent material.

Embodiment 5

The preparation method of the cationic polyacrylamide solution is shown in Embodiment 1.

1 g of lignosulfonate was dissolved in 200 mL of distilled water, stirred evenly at 25°C until completely dissolved and mixed well; a resulting solution was stirred mechanically and evenly at 200 r/min; 0.05 g of well-prepared cationic polyacrylamide was added dropwise to the foregoing lignin solution and constantly stirred at this speed for 2 h. Product precipitates were let stand for 2 h, and a supernatant was removed; precipitates were centrifuged for 5 min at 5,000 r/min, and a supernatant was removed sequentially; the precipitates were repeatedly washed with water thrice, and subjected to vacuum freeze-drying for 48 h to obtain a final product, i.e., a lignin-based adsorbent material.

Embodiment 6

The preparation method of the cationic polyacrylamide solution is shown in Embodiment 2.

5 g of lignosulfonate was dissolved in 200 mL of distilled water, stirred evenly at 25°C until completely dissolved and mixed well; a resulting solution was stirred mechanically and evenly at 300 r/min; 0.05 g of well-prepared cationic polyacrylamide was added dropwise to the foregoing solution and constantly stirred at this speed for 2 h. Product precipitates were let stand for 2 h, and a supernatant was removed; precipitates were centrifuged for 5 min at 5,000 r/min, and a supernatant was removed sequentially; the precipitates were repeatedly washed with water thrice, and subjected to vacuum freeze-drying for 48 h to obtain a final product, i.e., a lignin based adsorbent material.

Embodiment 7

The preparation method of the chitosan solution is shown in Embodiment 3.

2 g of lignosulfonate was dissolved in 200 mL of distilled water, stirred evenly at 25°C until completely dissolved and mixed well; a resulting solution was stirred mechanically and evenly at 500 r/min; 0.5g of well-prepared chitosan was added dropwise to the foregoing solution and constantly stirred at this speed for 2 h. Product precipitates were let stand for 2 h, and a supernatant was removed; precipitates were centrifuged for 5 min at 5,000 r/min, and a

supernatant was removed sequentially; the precipitates were repeatedly washed with water thrice, and subjected to vacuum freeze-drying for 48 h to obtain a final product, i.e., a lignin-based adsorbent material.

Embodiment 8

The preparation method of the chitosan solution is shown in Embodiment 4.

3 g of lignosulfonate was dissolved in 200 mL of distilled water, stirred evenly at 25°C until completely dissolved and mixed well; a resulting solution was stirred mechanically and evenly at 400 r/min; 0.4 g of well-prepared chitosan was added dropwise to the foregoing solution and constantly stirred at this speed for 2 h. Product precipitates were let stand for 2 h, and a supernatant was removed; precipitates were centrifuged for 5 min at 5,000 r/min, and a supernatant was removed sequentially; the precipitates were repeatedly washed with water thrice, and subjected to vacuum freeze-drying for 48 h to obtain a final product, i.e., a lignin-based adsorbent material.

The bio-based materials prepared in Embodiments 1 to 4 were respectively subjected to boric acid adsorbent material adsorption/desorption experiments. The specific experimental results are shown in Table 1:

Table 1 The adsorption and desorption effects of different materials on boric acid Sample Adsorption capacity for boric acid (mg/g) Desorption rate

Embodiment 1 53.4 90%

Embodiment 2 77.6 91%

Embodiment 3 49.8 89%

Embodiment 4 50.3 88%

Embodiment 5 2.0

Embodiment 6 3.5

Embodiment 7 4.6

Embodiment 8 3.8

It can be seen from the above data that lignin-tannic acid-cationic polymer assembled polymer has a higher boric acid adsorption function than the material assembled by lignin alone.

The specific processes of adsorption and desorption used in the above experiments are as follows:

Adsorption process:

0.3 g of the bio-based adsorbent material prepared above was placed in 300 mL of 500 g/L boric acid solution and adsorbed in a thermostatic oscillator, the boric acid solution was adjusted to pH=9 with 0.5 mol/L NaOH, and adsorption reaction was performed for 2 h at 25°C. The azomethine-H method was used to measure the absorbance of boric acid under 415 nm ultraviolet-visible light, further measure the adsorption of boric acid by the adsorbent material under different conditions, calculates the amount of boric acid adsorbent material, and compare the amount with the amount of boric acid adsorbed by lignin alone.

A=V(CO-C)/1OOOG

where:

A is the adsorption capacity of a bio-based material for boric acid, in mg/g;

V is the volume of boric acid solution, in mL;

CO is the concentration of boric acid before adsorption, in mg/L;

C is the concentration of boric acid after adsorption, in mg/L.

G is the amount of absorbent material, in g;

Desorption process:

After the adsorption reaction, the adsorption capacity of adsorbent material was determined; the adsorbent material was placed in 300 mL of an aqueous solution (pH = 4) adjusted by 0.5 mol/L HCl. After desorption reaction in a thermostatic oscillator at 25°C for 30 min, the concentration of boric acid in the solution was determined, and desorption rate was calculated. The calculation formula is:

E%=(CV/A) x 100%

where, C is the concentration of boric acid in a desorption solution, in mg/L;

V is the volume of the desorption solution, in mL;

A is the adsorption capacity of boric acid for adsorbent material, in mg/g.

In order to prove the carrier effect of lignin on lignin-tannic acid-cationic polymer assembled bio-based adsorbent material, in the present disclosure, 1 g of tannic acid was dissolved in a 500 mg/L boric acid solution and adjusted to pH 9. The result is shown in FIG. 3. From the figure, when tannic acid singly adsorbs boric acid, the boric acid solution becomes turbid, and this turbid liquid is difficult to be separated in a simple manner. Therefore, the carrier effect of lignin on the adsorbent material is particularly important.

Due to the low concentration of boric acid in the marine environment, the present disclosure adopts a method for measuring the adsorption rate to verify the removal rate of low-concentration boric acid by the prepared adsorbent material. The specific method is shown above: except that the initial concentration of boric acid is changed to 10 mg/L, other conditions remain unchanged. The method for calculating the removal rate of boric acid is:

A%=[V(CO-C)-V(CO-C1)]/VCO

where:

A is the adsorption capacity of a bio-based material for boric acid, in mg/g;

V is the volume of boric acid solution, in mL;

CO is the concentration of boric acid before adsorption, in mg/L;

C is the concentration of boric acid after adsorption, in mg/L;

C1 is the concentration of boric acid absorbed by lignin alone, in mg/L.

The experimental results are shown in Table 2:

Table 2 The removal rate of low concentration boric acid by different materials Removal rate of boric acid Residual concentration of boric acid Sample (%) (mg/L)

Embodiment 97 0.3 1

Embodiment 96 0.4 2

Embodiment 96 0.4 3

Embodiment 96 0.4 4

Embodiment 6.2 9.4 5

Embodiment 7.1 9.3 6

Embodiment 7.2 9.3 7

Embodiment 6.5 9.4 8

It follows that after adsorption, the lignin-tannic acid and cationic polymer assembled material has a high removal effect on low-concentration boric acid, and residual concentrations of boric acid in the solution after treatment are less than 0.5 mg/L, which reach the standards for drinking water quality. When lignin acts alone, the removal effect of boric acid is relatively low. This fully illustrates the advantages of the bio-based adsorbent material of the present disclosure in absorbing boric acid.

The parts not involved in the present disclosure are the same as the prior art or can be realized by using the prior art. Obviously, the above-mentioned embodiments of the present disclosure are merely intended to describe the examples clearly, but not to limit the embodiments of the present disclosure. Different forms of variations or alterations may also be made by those of ordinary skill in the art based on the above descriptions. It is unnecessary and impossible to list all embodiments herein. Any modification, equivalent replacement and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the claims of the present disclosure.

Claims

What is claimed is:

1. A boric acid adsorbent material, wherein raw materials thereof comprise the following components:

2. The boric acid adsorbent material according to claim 1, wherein the cationic polymer is a compound with a positive charge on the surface.

3. The boric acid adsorbent material according to claim 1, wherein the cationic polymer is cationic polyacrylamide or chitosan;

wherein the cationic polyacrylamide is dissolved in a 4% ethanol aqueous solution with a concentration of 2%o;

wherein the chitosan is dissolved in a 5% acetic acid aqueous solution with a concentration of 1.6%;

wherein the amount of tannic acid, lignosulfonate and cationic polymer is on an absolute dry basis.

4. A method for preparing a boric acid adsorbent material according to any one of claims 1 to 3, comprising the following steps:

S2. adding a cationic polymer solution to a mixed solution, and stirring until flocculent substances appear and no longer increase;

S3. letting the mixed solution stand for 2 h;

S5. removing a supernatant, and washing precipitates thrice with water; and

S6. conducting vacuum freeze-drying for 48 h.

5. The method for preparing a boric acid adsorbent material according to claim 4, wherein mixing temperature is 25°C;

wherein in step S2, the cationic polymer solution is a cationic polyacrylamide solution; wherein in step S2, the cationic polymer solution is added dropwise.