A self-supporting wood-based adsorbent, its preparation method and application

Abstract

This invention belongs to the field of environmental functional materials technology, specifically relating to a self-supporting wood-based adsorbent, its preparation method, and its application. The self-supporting wood-based adsorbent uses natural wood as a substrate. While maintaining the inherent three-dimensional porous framework of natural wood, cyano groups are introduced onto the cellulose of natural wood through a cyanoethylation reaction, and then the cyano groups are converted in situ into amamidoxime groups through an amamidoxime reaction, resulting in a self-supporting wood-based adsorbent with a three-dimensional porous structure. This invention successfully prepares a self-supporting bulk adsorbent material by functionalizing natural wood with amamidoxime while completely maintaining the inherent high-strength three-dimensional porous framework of wood. The modified amamidoxime groups not only exhibit high selectivity and strong adsorption capacity for gold ions, but also can reduce them in situ to elemental gold during adsorption, thereby significantly improving recovery efficiency.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials technology, specifically relating to a self-supporting wood-based adsorbent, its preparation method, and its application. Background Technology

[0002] Gold, a scarce precious metal, is crucial in fields such as electronics, catalysis, jewelry, and finance. With increasingly scarce mineral resources, recovering gold from secondary resources such as electronic waste and industrial wastewater has become an important issue. These resources typically contain low concentrations of gold and have complex compositions, thus requiring a technology capable of efficiently and selectively adsorbing gold.

[0003] Currently, most mainstream processes for recovering gold from waste liquids employ a combination of reagent reduction and multiple dissolution separation. First, a large amount of reducing agent is used to reduce various metal ions in the solution. The leachate is then repeatedly circulated for dissolution, resulting in the separation and purification of gold. Industrial production commonly uses aqua regia leaching, cyanide leaching, and thermometallurgical methods, which are not only costly but also extremely environmentally harmful. The development of gold adsorbents can achieve efficient and selective separation of gold, significantly reducing reagent usage and waste liquid discharge, and has attracted widespread attention in recent years. Gold adsorbents have advantages such as simple operation, fast adsorption speed, and low cost, and are considered a promising method. However, since gold-containing waste liquids and cyanide leaching solutions typically contain various metal ions, inorganic salts, and organic salts, traditional adsorbents such as activated carbon or zeolite usually have either low adsorption capacity or poor selectivity. Based on these considerations, providing a novel adsorbent is an important research topic that urgently needs to be addressed. Summary of the Invention

[0004] The purpose of this invention is to provide a self-supporting wood-based adsorbent that solves the problems existing in the prior art.

[0005] The technical solution adopted in this invention is: This invention provides a self-supporting wood-based adsorbent. The self-supporting wood-based adsorbent uses natural wood as a substrate. While maintaining the inherent three-dimensional porous framework of natural wood, cyano groups are introduced into the cellulose of natural wood through a cyanoethylation reaction, and then the cyano groups are converted into amamidoxime groups in situ through an amamidoxime reaction, resulting in a self-supporting wood-based adsorbent with a three-dimensional porous structure.

[0006] A second aspect of this invention provides a method for preparing the self-supporting wood-based adsorbent, comprising the following steps: S1. Natural wood is impregnated in an alkaline aqueous solution of acrylonitrile. Under alkaline conditions, the hydroxyl groups in the cellulose of the natural wood are activated, thereby initiating a Michael addition reaction between cellulose and acrylonitrile to obtain cyanoethylated wood. The mass-volume ratio of natural wood to acrylonitrile is 1g~5g:30mL~50mL. S2. The cyanoethylated wood is impregnated in an alkaline aqueous solution of hydroxylamine hydrochloride, so that the activated hydroxylamine reacts with the cyanoethylated wood to convert the cyano group into an amoxime group, thereby obtaining amoxime-treated wood, which is the self-supporting wood-based adsorbent; wherein the ratio of natural wood to hydroxylamine hydrochloride is 1g~5g:0.1mol~0.25mol.

[0007] Preferably, the mass-to-volume ratio of the natural wood to acrylonitrile is 1g:30mL.

[0008] Preferably, the ratio of natural wood to hydroxylamine hydrochloride is 1g:0.1mol.

[0009] Preferably, the conditions for the Michael addition reaction between cellulose and acrylonitrile are: 200 rpm to 400 rpm, 12 h to 24 h.

[0010] Preferably, the conditions for the addition reaction of activated hydroxylamine with cyanoethylated wood are: 70°C, reaction time 24h~72h.

[0011] Preferably, the natural wood is balsa wood.

[0012] A third aspect of the present invention provides an application of the self-supporting wood-based adsorbent, wherein the self-supporting wood-based adsorbent is used as a fixed-bed filling material or a dosing adsorbent for gold recovery.

[0013] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a self-supporting wood-based adsorbent. Using natural wood as a substrate, the adsorbent introduces cyano groups onto the cellulose of the natural wood through a cyanoethylation reaction while maintaining the inherent three-dimensional porous framework of the wood. Then, through an amide oxime reaction, the cyano groups are converted in situ into amide oxime groups, resulting in a self-supporting wood-based adsorbent with a three-dimensional porous structure. This invention successfully prepares a self-supporting bulk adsorbent material by functionalizing natural wood with amide oximes, while completely preserving the inherent high-strength three-dimensional porous framework of the wood. The modified amide oxime groups not only exhibit high selectivity and strong adsorption capacity for gold ions but also can reduce them in situ to elemental gold during adsorption, thereby significantly improving recovery efficiency. The self-supporting bulk shape of this material facilitates operation and recycling, and its adsorption kinetics based on internal pore diffusion make it particularly suitable for continuously operating fixed-bed column adsorption processes. The overall method uses renewable wood as a green substrate and combines functional design to achieve efficient and selective gold recovery and reduction while demonstrating the sustainability advantages of the entire process from raw materials to preparation and application. Attached Figure Description

[0014] Figure 1 The infrared spectrum of the self-supporting wood-based adsorbent prepared in Example 1.

[0015] Figure 2 The results show the adsorption of gold on amamidoxime-treated wood. a: XRD patterns of amamidoxime-treated wood before and after gold adsorption; b: Microscopic observation of amamidoxime-treated wood after gold adsorption.

[0016] Figure 3 Adsorption kinetics of amide oxime-treated wood.

[0017] Figure 4 The adsorption thermodynamics of amide oxime-treated wood.

[0018] Figure 5 The effect of pH on the adsorption of amide oxime in wood.

[0019] Figure 6 The adsorption selectivity of amide oxime-treated wood is improved.

[0020] Figure 7 Adsorption of amide oxime-treated wood in electronic waste liquid. Detailed Implementation

[0021] The present invention will be further illustrated below with specific embodiments, but these embodiments do not limit the scope of the invention. Modifications or substitutions to the details and form of the technical solutions of the present invention may be made without departing from the spirit and scope of the invention, but all such modifications or substitutions fall within the protection scope of the present invention.

[0022] The inventive concept of this invention is as follows: In-situ modification technology based on targeted recognition is considered one of the most promising emerging technologies for coupling the deep removal and resource recovery of precious metals in water due to its specific binding sites for target ion recognition. Considering that Au(III) ions usually exist in the form of complexes, their recovery process typically requires the participation of electrons and protons. A typical example is amine oxime functionalized compounds (AOs), a class of polymer materials containing >C=N-OH functional groups. Their ligand microenvironment can be flexibly adjusted, providing an ideal model for electron and proton transfer. Studies have shown that oxime groups can act as reactive sites to undergo complexation coordination or redox reactions with Au(III) ions. However, amine oxime functionalized polymers are often rigid and relatively hydrophobic, making them typically dense in aqueous solutions, lacking effective channels that make it difficult for metal ions to transfer into the polymer interior. Furthermore, most of these adsorbent materials are unstable crystalline powders, and due to high pressure drops and difficulty in separation, it is difficult to achieve column-packed adsorption to expand their industrial applications. For the reasons mentioned above, designing rigid amine oxime adsorbents with highly selective adsorption-reduction integration is a challenging task.

[0023] Wood, as a natural porous material, provides excellent contact conditions for adsorption due to its abundant pore structure. Its main components contain numerous functional groups such as hydroxyl, ether, and carboxyl groups, which can complex with heavy metal ions. Therefore, considering its structure and chemical composition, wood itself has the potential to be used as an adsorbent material. Developing new applications can effectively solve the problem of resource waste, realize its high-value utilization, and inspire new technological ideas for the treatment of industrial heavy metal ion wastewater. However, the complexing ability of the functional groups in wood is limited, which cannot fully utilize the advantages of its porous structure, resulting in a low adsorption capacity. Therefore, it is necessary to introduce more functional groups with strong complexing ability for gold-targeting capture, such as amamidoxime groups, into the structure.

[0024] Although composite materials based on ceramic membranes, polymer membranes, and inorganic-organic hybrid materials have been developed for rigid materials in recent years, their high preparation cost and complex processes hinder their further large-scale commercial application. Wood, as an extremely abundant and renewable lignocellulosic biomass material, possesses a multidimensional and multi-scale porous structure, a certain specific surface area, and a large number of surface-active groups, meeting the requirements of an ideal adsorbent material. Furthermore, its three-dimensional structure endows wood with natural mechanical strength, attracting attention in water treatment applications. The cellulose in wood contains a large number of hydroxyl groups (-OH), which can serve as a unique platform for modifying cellulose with functional molecules through various chemical methods to expand the material's applications. Combining the advantages of both amine oxime groups and wood, a novel amine-oxime-modified wood adsorbent material was designed. This material possesses both rigidity and specific target sites, and the unique open channel structure of the vertical arrangement and preservation of wood can greatly enhance the activity of the groups and the material's adsorption capacity.

[0025] Based on this, the present invention provides a deeply and uniformly cyanoethylated-aminooxime-modified self-supporting wood-based adsorbent suitable for bulk wood. The preparation method of the self-supporting wood-based adsorbent of the present invention can, under mild conditions, maximally maintain the inherent high-strength framework and interconnected micropores of wood, and construct a high-density specific gold adsorption sites (amidooxime groups) in situ on this framework, thereby preparing an integrated adsorbent material with excellent mechanical strength, high gold adsorption capacity, and superior selectivity, achieving efficient and green recovery of gold from complex aqueous solutions.

[0026] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention will be further described below with reference to specific embodiments. Unless otherwise specified, all reagents used in this invention are commercially available, and all methods used are conventional techniques in the art.

[0027] Example 1 A self-supporting wood-based adsorbent, the preparation method of which is as follows: S1, cyanoethylation is carried out via the Michael addition reaction between cellulose and acrylonitrile on balsa wood.

[0028] ① Mix 2 mL of 10 wt% NaOH aqueous solution with 30 mL of acrylonitrile, weigh 1 g of balsa wood and add it to the mixture of NaOH and acrylonitrile, and impregnate under vacuum for 3 h.

[0029] ② The above mixed solution was magnetically stirred at 300 rpm for 12 h at room temperature to complete the cyanoethylation.

[0030] ③ Add 10 mL of 1 wt% acetic acid solution to neutralize the mixture, and thoroughly wash the cyanoethylated wood with ultrapure water.

[0031] ④ Finally, after freeze-drying at -55°C, cyanoethylated wood is obtained.

[0032] S2. Aminooxime reaction occurs via electrophilic addition of cyano groups to hydroxylamine.

[0033] ① All the cyanoethylated wood obtained in S1 was impregnated in a 50 mL mixed solution of hydroxylamine hydrochloride (NH2OH·HCl) and NaOH under vacuum for 1 h. The concentration of hydroxylamine hydrochloride (NH2OH·HCl) and the concentration of NaOH in the mixed solution were both 2 mol / L.

[0034] ② After stirring the above mixed solution magnetically at 300 rpm for 6 hours at room temperature, the amide oxime reaction was carried out at 70°C and stirred at 800 rpm for 24 hours.

[0035] ③ The solid sample was thoroughly washed with ultrapure water and then freeze-dried at -55°C to obtain amide-oxime-treated wood, which is the self-supporting wood-based adsorbent.

[0036] Example 2 A self-supporting wood-based adsorbent, the preparation method of which is as follows: S1, cyanoethylation is carried out via the Michael addition reaction between cellulose and acrylonitrile on balsa wood.

[0037] ① Mix 1 mL of 10 wt% NaOH aqueous solution with 40 mL of acrylonitrile, weigh 2 g of balsa wood and add it to the mixture of NaOH and acrylonitrile, and impregnate under vacuum for 1 hour.

[0038] ② The above mixed solution was magnetically stirred at 200 rpm for 16 h at room temperature to complete the cyanoethylation.

[0039] ③ Add 15 mL of 1 wt% acetic acid solution to neutralize the mixture, and thoroughly wash the cyanoethylated wood with ultrapure water.

[0040] ④ Finally, after freeze-drying at -55°C, cyanoethylated wood is obtained.

[0041] S2. Aminooxime reaction occurs via electrophilic addition of cyano groups to hydroxylamine.

[0042] ① All the cyanoethylated wood obtained in S1 was impregnated in a 50 mL mixed solution of hydroxylamine hydrochloride (NH2OH·HCl) and NaOH for 2 h under vacuum. The concentration of hydroxylamine hydrochloride (NH2OH·HCl) and the concentration of NaOH in the mixed solution were both 3 mol / L.

[0043] ② After stirring the above mixed solution magnetically at 200 rpm for 3 h at room temperature, the amide oxime reaction was carried out at 70°C with stirring at 900 rpm for 36 h.

[0044] ③ The solid sample was thoroughly washed with ultrapure water and then freeze-dried at -55°C to obtain amide-oxime-treated wood, which is the self-supporting wood-based adsorbent.

[0045] Example 3 A self-supporting wood-based adsorbent, the preparation method of which is as follows: S1, cyanoethylation is carried out via the Michael addition reaction between cellulose and acrylonitrile on balsa wood.

[0046] ① Mix 5 mL of 10 wt% NaOH aqueous solution with 50 mL of acrylonitrile, weigh 5 g of balsa wood and add it to the mixture of NaOH and acrylonitrile, and impregnate under vacuum for 2 hours.

[0047] ② The above mixed solution was magnetically stirred at 400 rpm for 24 h at room temperature to complete the cyanoethylation.

[0048] ③ Add 20 mL of 1 wt% acetic acid solution to neutralize the mixture, and thoroughly wash the cyanoethylated wood with ultrapure water.

[0049] ④ Finally, after freeze-drying at -55°C, cyanoethylated wood is obtained.

[0050] S2. Aminooxime reaction occurs via electrophilic addition of cyano groups to hydroxylamine.

[0051] ① All the cyanoethylated wood obtained in S1 was impregnated in a 50 mL mixed solution of hydroxylamine hydrochloride (NH2OH·HCl) and NaOH for 3 h under vacuum. The concentration of hydroxylamine hydrochloride (NH2OH·HCl) and the concentration of NaOH in the mixed solution were both 5 mol / L.

[0052] ② After stirring the above mixed solution magnetically at 400 rpm for 5 h at room temperature, the amide oxime reaction was carried out at 70°C with stirring at 1000 rpm for 72 h.

[0053] ③ The solid sample was thoroughly washed with ultrapure water and then freeze-dried at -55°C to obtain amide-oxime-treated wood, which is the self-supporting wood-based adsorbent.

[0054] As verified by this invention, the self-supporting wood-based adsorbents prepared in Examples 1 to 3 showed no significant difference in performance. Therefore, this invention only presents the relevant data of the self-supporting wood-based adsorbent prepared in Example 1.

[0055] Example 4 The application of a self-supporting wood-based adsorbent is described in this embodiment. The effectiveness of the self-supporting wood-based adsorbent prepared in Example 1 is verified as follows: 1. Fourier transform infrared spectroscopy (FT-IR).

[0056] Infrared full-spectrum observations revealed that cyanoethylated wood at 2252 cm⁻¹ -1 A sharp new peak appears at 2252 cm⁻¹, which is the characteristic stretching vibration peak of the cyano group (C≡N); amidooxime-treated wood shows a peak at 2252 cm⁻¹. -1 The complete disappearance of the cyano peak indicates that the cyano group has completely reacted, and the peak at 1654 cm⁻¹... -1 and 992cm -1 Two new characteristic peaks appeared, which are attributed to the stretching vibrations of the C=N and NO bonds in the amamidoxime group, respectively. These results prove that the cyano group was successfully converted into an amamidoxime group. See the results below. Figure 1 .

[0057] 2. X-ray diffraction (XRD).

[0058] exist Figure 2 The XRD pattern of a shows that the structure of the amidated wood completely changed after gold adsorption, with four different peaks appearing at 38°, 44°, 64°, and 77° of the 2θ angle, which can be compared with elemental gold (Au). 0 The (111), (200), (220), and (311) crystallographic planes of the face-centered cubic lattice structure correspond, proving that redox adsorption occurred; simultaneously, in Figure 2 In sample b, a polarizing microscope revealed that the pores inside the material were filled with a large amount of elemental gold, indicating that the amyloxime-modified wood has strong reducing activity and can give Au(III) sufficient electrons to reduce it to elemental form.

[0059] 3. Adsorption experiment.

[0060] Au(III) solutions were prepared by dissolving HAuCl4 in ultrapure water. 5 g of HAuCl4 was dissolved in 100 mL of ultrapure water by ultrasonication to obtain a gold stock solution of 28.1146 g / L. The 28.1146 g / L stock solution was diluted with deionized water to obtain Au(III) solutions of different concentrations. The concentration of Au(III) in the water samples was determined using continuous-wave atomic absorption spectrometry to evaluate the adsorption effect of the adsorbent on Au(III). All experiments were performed three times, and the final data was the average of the three experiments.

[0061] This experiment was conducted to illustrate the adsorption rate of gold ions by the adsorbent. The specific implementation steps are as follows: 50 mg of amamidoxame-modified wood was added to 100 mL of Au(III) solutions with concentrations of 50 mg / L and 100 mg / L, respectively. The solutions were shaken in a constant temperature shaking chamber at 180 rpm. Samples were then taken at 0 h, 0.5 h, 1 h, 3 h, 7 h, 12 h, 24 h, and 48 h. The samples were filtered through a 0.45 μm polyethersulfone membrane to obtain the supernatant, and the change in Au(III) concentration before and after adsorption was determined using an ICP atomic emission spectrometer.

[0062] Figure 3 The adsorption kinetic curves show that the amamidoxime-treated wood achieves a recovery rate of over 99% for gold solutions of 50 mg / L and 100 mg / L, demonstrating an extremely high removal rate. The adsorption kinetic curves conform to second-order kinetics, with a correlation coefficient higher than 0.99, indicating that it belongs to chemisorption.

[0063] 4. This experiment is used to illustrate the effect of adsorption temperature on the adsorption capacity of amide oxime-modified wood adsorbents. The specific implementation steps are as follows: Ten mg of amamidoxime-modified wood was added to 10 mL of Au(III) solutions of different concentrations, and the solutions were shaken for 24 h at 180 rpm in constant-temperature shaking incubators at 15°C, 30°C, and 45°C, respectively. The initial concentrations of Au(III) in the adsorbent solutions ranged from 50 mg / L, 100 mg / L, 200 mg / L, 400 mg / L, 800 mg / L, 1200 mg / L, 1600 mg / L, and 2000 mg / L. After adsorption equilibrium was reached, the samples were filtered through a 0.45 μm polyethersulfone membrane to obtain the supernatant, and the change in Au(III) concentration before and after adsorption was determined using ICP atomic emission spectrometry. The results showed that the adsorption capacity of the amamidoxime-modified wood adsorbent for Au(III) reached an adsorption equilibrium capacity of 600 mg / g at 30°C, which is a considerable recovery amount in bulk materials. Furthermore, the adsorption capacity increased with increasing temperature, indicating that the adsorption process was an endothermic reaction. The isotherm curves conform to the Freundlich model, indicating multilayer adsorption, which is closely related to the abundant pores in the wood. See results below. Figure 4.

[0064] 5. The effect of pH.

[0065] Nine 10 mL solutions of Au(III) with an initial concentration of 50 mg / L were prepared, and the pH of the Au(III) solutions was adjusted sequentially to 1, 2, 3, 4, 5, 6, 7, 8, and 9. 10 mg of amamidoxime-modified wood adsorbent was added to each of the 10 mL Au(III) solutions at different pH values ​​for adsorption. The mixture was shaken at a constant speed of 180 rpm for 24 h at 30 °C. After adsorption equilibrium was reached, the supernatant was collected by filtration through a pinhole membrane. The change in Au(III) concentration before and after adsorption was measured using ICP atomic emission spectrometry to evaluate the adsorption effect under different pH conditions.

[0066] Figure 5 The pH effect diagram shows that the amidine-oxime-modified wood adsorbent exhibits a wide pH operating range for Au(III) adsorption under conditions of pH 1–7. Even under harsh conditions at pH 1, the recovery of gold from amidine-oxime-modified wood can reach over 40%. Therefore, this adsorbent material has the advantages of acid resistance and a wide range of applications, which is beneficial for industrial gold recovery.

[0067] 6. Selective adsorption.

[0068] Add 10 mg of amidoxime-modified wood adsorbent to 10 mL of solution containing Au. 3+ Cu 2+ Ni 2+ Pb 2+ K + Cd 2+ Zn 2 + and Ca 2+ The solution was prepared by mixing eight ions at a concentration of 50 mg / L. Then, it was shaken in a constant temperature shaking oven at 30 °C for 24 h. After adsorption equilibrium was reached, the supernatant was collected by filtering through a needle filter, and the concentration of each component ion in the supernatant was determined by ICP atomic emission spectrometry.

[0069] Depend on Figure 6 It can be seen that this amide oxime-modified wood adsorbent can adsorb Au in a mixed solution. 3+ The material selectively separates from other metal ions, achieving a removal rate close to 100%, indicating that this amide-oxime-modified wood adsorbent effectively removes Au from complex solutions containing mixed gold ions. 3+ It offers excellent selectivity.

[0070] 7. Adsorption test of electronic waste liquid.

[0071] 10 mg of amoxime-modified wood adsorbent was added to 10 mL of digestion solution for pins, motherboards, and Wi-Fi boards, respectively. Then, the mixture was shaken in a constant temperature shaking chamber at 30 °C for 24 h. After adsorption equilibrium, the supernatant was collected by filtering through a needle filter, and the concentration of each component ion in the supernatant was determined by ICP atomic emission spectrometry.

[0072] from Figure 7 As can be seen from the data, this amide oxime-modified wood adsorbent material can remove Au from actual electronic waste liquid. 3+ The selective separation from other metal ions indicates that this amide-oxime-modified wood adsorbent material effectively removes Au from actual electronic waste liquids. 3+ It offers excellent selectivity.

[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0074] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A self-supporting wood-based adsorbent, characterized in that, The self-supporting wood-based adsorbent uses natural wood as a base. While maintaining the inherent three-dimensional porous framework of natural wood, cyano groups are introduced into the cellulose of natural wood through a cyanoethylation reaction, and then the cyano groups are converted into amamidoxime groups in situ through an amamidoxime reaction, resulting in a self-supporting wood-based adsorbent with a three-dimensional porous structure.

2. The method for preparing the self-supporting wood-based adsorbent as described in claim 1, characterized in that, The steps are as follows: S1. Natural wood is impregnated in an alkaline aqueous solution of acrylonitrile. Under alkaline conditions, the hydroxyl groups in the cellulose of the natural wood are activated, thereby initiating a Michael addition reaction between cellulose and acrylonitrile to obtain cyanoethylated wood. The mass-volume ratio of natural wood to acrylonitrile is 1g~5g:30mL~50mL. S2. The cyanoethylated wood is impregnated in an alkaline aqueous solution of hydroxylamine hydrochloride, so that the activated hydroxylamine reacts with the cyanoethylated wood to convert the cyano group into an amoxime group, thereby obtaining amoxime-treated wood, which is the self-supporting wood-based adsorbent; wherein the ratio of natural wood to hydroxylamine hydrochloride is 1g~5g:0.1mol~0.25mol.

3. The preparation method according to claim 2, characterized in that, The mass-to-volume ratio of the natural wood to acrylonitrile is 1g:30mL.

4. The preparation method according to claim 2, characterized in that, The ratio of natural wood to hydroxylamine hydrochloride is 1g:0.1mol.

5. The preparation method according to claim 2, characterized in that, The conditions for the Michael addition reaction between cellulose and acrylonitrile are: 200 rpm to 400 rpm, 12 h to 24 h.

6. The preparation method according to claim 2, characterized in that, The conditions for the addition reaction of activated hydroxylamine with cyanoethylated wood are: 70℃, reaction time 24h~72h.

7. The preparation method according to claim 2, characterized in that, The natural wood in question is balsa wood.

8. The application of the self-supporting wood-based adsorbent as described in claim 1, characterized in that, The self-supporting wood-based adsorbent is used as a fixed-bed filling material or a dosing adsorbent for gold recovery.

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