Adsorptive material for efficiently removing mercury and preparation method thereof

Abstract

The application discloses an adsorbing material for efficiently removing mercury and a preparation method thereof. The preparation method comprises the following steps: cutting cellulose, and washing the cellulose in anhydrous ethanol by ultrasonic to remove impurities, and obtaining defatted cellulose after vacuum drying; adding the defatted cellulose into an organic solution containing bromoacetyl bromide, stirring and reacting at 25-60 DEG C for 24-72 h, then filtering, washing with anhydrous ethanol, and drying to obtain brominated cellulose; under the protection of nitrogen, adding the brominated cellulose and sodium hydrosulfide into anhydrous ethanol, stirring and reacting at 60-90 DEG C for 24-96 h, then filtering, washing with water or ethanol, and drying to obtain the adsorbing material. The application has low cost, can effectively improve the density and dispersity of mercapto functional groups in the adsorbing material, can efficiently and quickly remove mercury in various media, and the prepared adsorbing material has good stability and selectivity.

Description

Technical Field

[0001] This invention belongs to the field of materials technology and relates to an adsorbent material for the efficient removal of mercury and its preparation method, for use with inorganic mercury ions (Hg) in water. 2+ Mercury in dissolved complex (Hg-DOM) and mercury vapor in the air (Hg) 0 Rapid and efficient removal of phenylmercuric chloride (PMC) from organic solvents. Background Technology

[0002] Rapid development of human society and industry has released large amounts of mercury into the environment, posing a significant threat to global ecosystems and public health, and drawing widespread attention from countries worldwide. Mercury is one of the most toxic heavy metals, with over 6,000 tons of mercury in various forms released into the environment annually through industrial products / byproducts and related processes. Due to its high toxicity and strong bioaccumulation, even trace amounts of mercury can severely damage the human reproductive, digestive, central nervous system, and brain, posing a serious threat to public health and the environment. Over the past few decades, numerous technologies have been developed for mercury removal, such as chemical precipitation, membrane separation, oxidation / reduction, biological treatment, electrolysis, and adsorption. Among these, adsorption is considered one of the most effective methods for removing trace heavy metals due to its low cost, operational flexibility, lack of byproducts, and reusability.

[0003] Traditional adsorbents such as activated carbon, zeolite, nano-metal oxides, and resins have been widely used to remove mercury from wastewater. However, these adsorbents suffer from low adsorption capacity, slow kinetics, and poor selectivity, which limits their practical application, particularly their ability to rapidly remediate sudden mercury pollution events. According to Lewis acid-base theory, soft base ligands (thiol / sulfur-containing functional groups) can form strong coordination bonds with the soft acid heavy metal mercury. Therefore, numerous studies have focused on thiolizing / sulfurizing existing traditional adsorbent materials such as clay, resin, mesoporous silica, activated carbon, and mesoporous carbon to improve mercury removal efficiency. However, due to the low density and uneven distribution of grafted sulfur-containing functional groups, traditional sulfur-functionalized adsorbent materials have low affinity for mercury, making it difficult to reduce mercury concentrations to levels permissible by drinking water standards.

[0004] In recent years, novel adsorbent materials such as metal-organic frameworks (MOFs) and porous organic polymers (POPs) have attracted widespread attention in the field of mercury removal due to their high surface area, programmable functional groups, and high dispersibility. Modification of MOFs / POSs frameworks with sulfur-containing functional groups has demonstrated high adsorption efficiency and rapid removal rate for Hg, with adsorption capacities exceeding 500 mg / g and residual Hg concentrations below 1 ppb. However, MOFs are generally unstable in water, especially in wastewater with significant pH fluctuations, while POPs suffer from high raw material costs and overly complex synthesis processes, severely limiting the practical application of these novel mercury adsorbent materials. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide an adsorbent material for efficient mercury removal and its preparation method. This invention is low in cost, effectively improves the density and dispersibility of thiol functional groups in the adsorbent material, and can efficiently and rapidly remove mercury from various media. Furthermore, the prepared adsorbent material exhibits good stability and selectivity.

[0006] The technical solution of this invention is implemented as follows:

[0007] A method for preparing an adsorbent material for efficient mercury removal involves adding defatted cellulose to an organic solution containing bromine acetyl bromide to bromate the cellulose, thereby obtaining cellulose bromide; then, under nitrogen protection, reacting the cellulose bromide with sodium hydrosulfide to thiolize the cellulose bromide, thus obtaining the adsorbent material.

[0008] Furthermore, the specific steps include:

[0009] (1) The cellulose was cut into pieces and ultrasonically washed in anhydrous ethanol to remove impurities. After vacuum drying, defatted cellulose was obtained.

[0010] (2) Add defatted cellulose to an organic solution containing bromoacetyl bromide, stir and react at 25-60°C for 24-72 h, then filter and wash with anhydrous ethanol, and dry to obtain brominated cellulose;

[0011] (3) Under nitrogen protection, cellulose bromide and sodium hydrosulfide are added to anhydrous ethanol and stirred at 60-90°C for 24-96 h. The mixture is then filtered, washed with water or ethanol, and dried to obtain the adsorbent material.

[0012] Furthermore, the cellulose is one of lignocellulose and cotton cellulose. Preferably, the cotton fiber is cotton cellulose.

[0013] Further, the organic solution is obtained by dissolving bromoacetyl bromide in an organic solvent, wherein the volume fraction of bromoacetyl bromide in the organic solution is 1-5%; the organic solvent is one or more of N,N-dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide. Preferably, the organic solvent is N,N-dimethylformamide.

[0014] Furthermore, in step (2), the mass-to-volume ratio of defatted cellulose to organic solution is 1 g: 50-150 mL.

[0015] Furthermore, the mass ratio of cellulose bromide to sodium hydrosulfide is 1:3 to 1:7.

[0016] Furthermore, in step (3), the added anhydrous ethanol is sufficient to completely dissolve the sodium hydrosulfide.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. This invention uses natural cellulose as raw material and uses bromoacetyl bromide to bromate the abundant hydroxyl groups on the surface and inside of cellulose into bromohydrocarbons; then, sodium hydrosulfide is used to thiolate the bromohydrocarbons, thereby converting the bromohydrocarbons into thiol groups. At the same time, due to the weak acidity of sodium hydrosulfide, it can partially degrade and strip the cellulose, thereby making the prepared adsorbent material have high specific area and porosity.

[0019] 2. The adsorbent material prepared by this invention exhibits good adhesion to Hg within a pH range of 1–12. 2+ Both exhibit high adsorption efficiency, with a maximum adsorption capacity of 652.9 mg / g, and can also be used for Hg. 0 Effective removal of organic Hg from steam and organic phases, exhibiting good chemical stability and selectivity, and can be recycled up to 20 times. 2+ The removal rate is still above 95%.

[0020] 3. The main raw material used in this invention is natural cellulose, which is widely available and low in cost. The other raw materials are all conventional chemical reagents, which can effectively reduce the production cost of adsorption materials. Moreover, the preparation method is simple, the conditions are mild, and no high-temperature operation is involved, which has wide application value. Attached Figure Description

[0021] Figure 1 - Physical images of CU, CU-Br, and CU-SH in Example 1.

[0022] Figure 2 - SEM image and corresponding EDS spectrum of CU in Example 1.

[0023] Figure 3 - SEM image and corresponding EDS spectrum of CU-Br in Example 1.

[0024] Figure 4 - SEM images and corresponding EDS spectra of CU-SH in Example 1.

[0025] Figure 5 XPS energy dispersive spectroscopy analysis of CU, CU-Br and CU-SH in Example 1.

[0026] Figure 6 - N2 adsorption-desorption isotherms of CU, CU-Br and CU-SH in Example 1.

[0027] Figure 7 - Pore size distribution of CU, CU-Br and CU-SH in Example 1.

[0028] Figure 8 -In Example 1, CU, CU-Br, and CU-SH affect Hg 2+ Adsorption over time curve.

[0029] Figure 9 -In Example 1, CU-SH affects Hg at different pH values. 2+ Adsorption efficiency.

[0030] Figure 10 -In Example 1, CU-SH affects Hg in water 2+ Adsorption test.

[0031] Figure 11 -In Example 1, CU-SH complexes dissolved Hg in water 2+ Adsorption test of (Hg-DOM).

[0032] Figure 12 - Adsorption test of CU-SH on phenylmercuric chloride in n-dodecane in Example 1.

[0033] Figure 13 -In Example 1, CU-SH affects Hg 0 The adsorption efficiency of steam.

[0034] Figure 14 -In Example 1, CU-SH simulates Hg 2+ Hg in polluted drinking water 2+ The removal of.

[0035] Figure 15 - The removal efficiency of CU-SH for Hg after different regeneration cycles in Example 1.

[0036] Figure 16 -SEM images and corresponding EDS spectra of CU-SH after 20 regenerations in Example 1.

[0037] Figure 17XPS energy dispersive spectroscopy analysis of CU-SH after 20 regenerations in Example 1. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0039] Example 1

[0040] 1.0 g of cotton cellulose (CU) was chopped and ultrasonically washed in anhydrous ethanol for 10 minutes to remove impurities. After vacuum drying, the defatted cotton cellulose was added to 100 mL of DMF solution containing 3% bromoacetyl bromide and stirred at 40 °C for 48 hours. The mixture was then filtered and the solid was washed with anhydrous ethanol and vacuum dried at room temperature to obtain cellulose bromide (CU-Br). Under N2, CU-Br and sodium hydrosulfide (5.2 g) were added to 200 mL of anhydrous ethanol and stirred at 75 °C for 3 days. As the brominated hydrocarbon groups were converted to thiols, the cellulose was exfoliated. The final product was collected by filtration, washed thoroughly with deionized water and ethanol, and vacuum dried at room temperature to obtain an adsorbent material in the form of a brown powder (exfoliated thiolized cellulose, CU-SH).

[0041] Example 2

[0042] This embodiment is the same as Embodiment 1, except that the volume fraction of bromoacetyl bromide in the DMF solution in this embodiment is 1%.

[0043] Example 3

[0044] This embodiment is the same as Embodiment 1, except that the volume fraction of bromoacetyl bromide in the DMF solution in this embodiment is 5%.

[0045] Example 4

[0046] This embodiment is the same as Embodiment 1, except that the amount of sodium hydrosulfide added in this embodiment is 3.0g.

[0047] Example 5

[0048] This embodiment is the same as Embodiment 1, except that the amount of sodium hydrosulfide added in this embodiment is 7.0g.

[0049] Example 6

[0050] This embodiment is the same as Embodiment 1, except that in this embodiment, the degreased cotton fibers and bromoacetyl bromide react at 25°C for 48 hours.

[0051] Example 7

[0052] This embodiment is the same as Embodiment 1, except that in this embodiment, the degreased cotton fibers and bromoacetyl bromide react at 60°C for 48 hours.

[0053] Example 8

[0054] This embodiment is the same as Embodiment 1, except that in this embodiment, cellulose bromide and sodium hydrosulfide are reacted at 60°C for 72 hours.

[0055] Example 9

[0056] This embodiment is the same as Embodiment 1, except that in this embodiment, cellulose bromide and sodium hydrosulfide are reacted at 90°C for 72 hours.

[0057] Comparative Example 1

[0058] This embodiment is the same as Embodiment 1, except that the volume fraction of bromoacetyl bromide in the DMF solution in this embodiment is 0.5%.

[0059] Comparative Example 2

[0060] This embodiment is the same as Embodiment 1, except that the volume fraction of bromoacetyl bromide in the DMF solution in this embodiment is 6%.

[0061] Comparative Example 3

[0062] This embodiment is the same as Embodiment 1, except that the amount of sodium hydrosulfide added in this embodiment is 2g.

[0063] Comparative Example 4

[0064] This embodiment is the same as Embodiment 1, except that the amount of sodium hydrosulfide added in this embodiment is 8g.

[0065] 1. The densities of thiol functional groups in the bio-based mercury adsorbent materials obtained in Examples 1 to 9 and Comparative Examples 1 to 4 are shown in Table 1.

[0066] Table 1. Density of thiol functional groups in the bio-based mercury adsorbent materials obtained in Examples 1-9 and Comparative Examples 1-4

[0067] Example Thiol group density (mmol / g) Example 1 2.62 Example 2 1.62 Example 3 3.08 Example 4 1.52 Example 5 2.72 Example 6 1.84 Example 7 3.22 Example 8 1.49 Example 9 2.52 Comparative Example 1 0.57 Comparative Example 2 3.11 Comparative Example 3 0.72 Comparative Example 4 2.43

[0068] As shown in the table above, the amounts of bromoacetyl bromide and sodium hydrosulfide significantly affect the content of thiol functional groups in modified cellulose, thus affecting the adsorption efficiency of Hg. When the volume fraction of bromoacetyl bromide is below 1%, the low grafting amount leads to a low thiol density. When the volume fraction of bromoacetyl bromide is above 5%, the thiol density in the modified cellulose no longer increases significantly due to the limited number of reactive hydroxyl groups on the cellulose. Therefore, the reasonable volume fraction of bromoacetyl bromide is 1%–5%, at which point the content of thiol functional groups in the modified cellulose is relatively high, reaching 1.62–3.08 mmol / g. Adding less than 3g of sodium hydrosulfide cannot effectively convert bromoalkane into thiol groups, while adding more than 7g results in an excess of sodium hydrosulfide relative to bromoalkane, causing reagent waste. Therefore, the reasonable amount of sodium hydrosulfide added is 3–7g. Furthermore, the reaction temperature also has a significant impact on the final thiol functional group density on the cellulose. Too low a temperature prevents the reaction from proceeding effectively, resulting in a low thiol density. Once the temperature is increased to a certain level, the reaction proceeds completely. Excessively high temperatures not only fail to increase the thiol grafting rate but also increase cellulose hydrolysis. Therefore, the reasonable temperature range for bromination of cellulose by bromoacetyl bromide is 25–60℃, and the reasonable temperature range for sodium hydrosulfide treatment is 60–90℃.

[0069] 2. Actual images of cotton cellulose (CU), cellulose bromide (CU-Br), and cellulose thiolated stripping (CU-SH) in Example 1 are shown below. Figure 1 As shown; the SEM image and corresponding EDS spectrum of CU are as follows. Figure 2 As shown; the SEM image and corresponding EDS spectrum of CU-Br are as follows. Figure 3 As shown; the SEM image and corresponding EDS spectrum of CU-SH are as follows. Figure 4 As shown; XPS energy dispersive spectroscopy analysis, N2 adsorption-desorption isotherms, and pore size distributions of CU, CU-Br, and CU-SH are respectively shown in the figures. Figure 5 , Figure 6 and Figure 7 As shown.

[0070] Depend on Figure 1 It can be seen that white cotton cellulose (CU) is brominated to become yellow cellulose bromide (CU-Br), and after thiolation, it yields brown powdery bio-based mercury adsorbent material (CU-SH).

[0071] Figure 2 SEM images show that cotton cellulose has a typical fiber structure with a very smooth fiber surface and an average diameter of approximately 15 μm. EDS spectroscopy shows that it mainly contains C and O elements, which are evenly distributed. The CU-Br obtained after bromination with bromoacetyl bromide retains the fiber structure, but the content of cellulose fragments in the interfiber spaces increases significantly, and obvious wrinkles are visible on the fiber surface. EDS analysis shows the presence of Br element, which is evenly distributed, proving that the bromination was successful. Figure 3After NaHS thiolation, CU-SH retained its fibrous structure, but the fiber size was significantly reduced, with an average diameter of approximately 1 μm. The fiber surface also became very rough, demonstrating that this modification successfully exfoliated the cotton fibers. EDS spectroscopy showed the disappearance of Br and the appearance and uniform distribution of S, proving that the thiol groups were successfully grafted onto the fiber surface. Figure 4 ).

[0072] XPS energy dispersive spectroscopy showed that cotton cellulose (CU) is mainly composed of C and O. After bromination, a typical Br 3d peak appeared in CU-Br. After NaHS thiolation, the Br 3d peak disappeared, and a characteristic S 2p peak appeared. The S element content was 8.38 wt%, approximately 2.62 mmol / g. Figure 5 The results were consistent with EDS analysis, confirming that a large number of SH functional groups were grafted into cellulose. Specific surface area analysis showed that the Cu specific surface area was only 0.7 m². 2 / g, after bromination, the specific surface area of ​​CU-Br increased to 108.39m². 2 / g, the specific surface area of ​​CU-SH after thiolization further increased to 278.06m². 2 / g( Figure 6 Pore ​​size analysis results showed that bromination and thiolation significantly reduced the pore size of cellulose, with the average pore size decreasing from Cud 46.59 nm to CU-SH 16.79 nm. Figure 7 ).

[0073] 3. Mercury adsorption tests were performed on Cu, Cu-Br, and Cu-SH from Example 1.

[0074] (1) Effects of CU, CU-Br and CU-SH on Hg 2+ Adsorption differences

[0075] The test conditions were: 60 mg of adsorbent was added to 300 mL of Hg solution with a concentration of 10 mg / L. 2+ In an aqueous solution, 3 mL of the mixture was taken at certain time intervals, filtered through a 0.45 μm filter membrane, and the Hg in the filtrate was detected using a cold atomic absorption mercury analyzer. 2+ concentration.

[0076] CU, CU-Br and CU-SH on Hg 2+ The adsorption-time curve is as follows: Figure 8 As shown, CU and CU-Br hardly adsorb Hg. 2+ Adsorption of Hg in solution for 4 hours 2+ The concentration did not decrease significantly, Hg 2+ The removal rate is less than 1%. In contrast, CU-SH can achieve Hg removal. 2+ Rapid and efficient removal, removing Hg within 1 minute. 2+The removal rate of 10 ppm reached 92%, and the removal rate of 10 min exceeded 99.8%.

[0077] (2) pH affects the adsorption of Hg by Cu-SH 2+ Impact

[0078] The test conditions were as follows: 10 mg of CU-SH (0.2 g / L) was added to 50 mL of Hg solution with a concentration of 200 mg / L. 2+ In an aqueous solution, the pH was adjusted to the set value (±0.05) using 1 mol / L nitric acid and 1 mol / L sodium hydroxide. After adsorption by vibration at 200 rpm for 2 hours at room temperature, the solution was filtered, and the Hg concentration in the filtrate was detected using a cold atomic absorption mercury analyzer.

[0079] CU-SH at different pH values ​​on Hg 2+ Adsorption efficiency such as Figure 9 As shown, CU-SH has a positive effect on Hg in the pH range of 1-12. 2+ All exhibit high adsorption efficiency, with adsorption capacities exceeding 300 mg / g. Among them, under near-neutral conditions (pH 3-8), CU-SH shows the best adsorption capacity for Hg. 2+ It exhibits superior adsorption efficiency, with an adsorption capacity exceeding 450 mg / g. Adsorption test results at different pH values ​​indicate that CU-SH can be used for Hg in wastewater with significant pH fluctuations. 2+ Highly efficient removal.

[0080] (3) CU-SH in aqueous medium for Hg 2+ Removal efficiency

[0081] The test conditions were as follows: 10 mg of CU-SH was added to 50 mL of Hg solution with a concentration gradient of 10-500 mg / L. 2+ In aqueous solution, the pH was adjusted to 5.0 ± 0.05 using 1 mol / L nitric acid and 1 mol / L sodium hydroxide, and adsorption was carried out at room temperature with vibration at 200 rpm for 24 h to reach adsorption equilibrium. After adsorption, the mixture was filtered through a 0.45 μm filter membrane, and the Hg concentration in the filtrate was determined using a cold atomic absorption mercury analyzer.

[0082] Test results are as follows Figure 10 As shown, the equilibrium concentration C e When the concentration is 0-30 mg / L, the adsorption capacity varies with C. e The concentration increased rapidly from 0 mg / g to 350 mg / g. C e With further increases in concentration, the adsorption capacity increases slowly, reaching a maximum of 652.9 mg / g. This indicates that CU-SH effectively adsorbs Hg in aqueous media. 2+ It has a high adsorption capacity.

[0083] (4) Removal efficiency of CU-SH for Hg-DOM in aqueous medium

[0084] Preparation of Hg-DOM was performed according to the reference (Environmental Science & Technology, 2021, 55(2):1231-1241). 2 mg of Cu-SH was added to 20 mL of an aqueous solution of Hg-DOM with a concentration gradient of 0.5-15 mg / L. Adsorption was carried out at room temperature and 200 rpm for 24 h to reach equilibrium. After adsorption, the mixture was filtered through a 0.45 μm filter membrane, and the Hg concentration in the filtrate was detected using a cold atomic absorption mercury analyzer.

[0085] Test results are as follows Figure 11 As shown, the equilibrium concentration C e When the concentration is 0-2.3 mg / L, the adsorption capacity of CU-SH for Hg-DOM varies with C. e The concentration increased rapidly from 0 mg / g to 27.5 mg / g. C e As the concentration continued to increase, the adsorption capacity increased slowly, reaching a maximum of 53.4 mg / g. This indicates that CU-SH also has high adsorption efficiency for dissolved complexed Hg in aqueous media.

[0086] (5) Removal efficiency of CU-SH for organic mercury (PMC) in organic solvent media

[0087] 2 mg of CU-SH was added to 20 mL of a phenylmercuric chloride solution in n-dodecane with a concentration gradient of 1–50 mg / L. The mixture was shaken at 200 rpm for 24 h at room temperature, and then filtered through a 0.45 μm glass fiber membrane. 1 mL of the filtrate was mixed with 1.5 mL of 0.2 N BrCl and 1.5 mL of concentrated HCl, and shaken at 200 rpm for 12 h to extract mercury from n-dodecane into water. The adsorption capacity of CU-SH for PMC in organic solvents was calculated by determining the mercury concentration in water.

[0088] The results are as follows Figure 12 As shown, the equilibrium concentration of PMC, C e When the concentration is 0-17 mg / L, the adsorption capacity of CU-SH for PMC varies with C. e The concentration increased rapidly from 0 mg / g to 127.4 mg / g. C e As the concentration continued to increase, the adsorption capacity increased slowly, reaching a maximum of 151.9 mg / g. This indicates that CU-SH has high adsorption efficiency for organic Hg in organic solvent media.

[0089] (6) CU-SH on Hg in air medium 0 Steam removal efficiency

[0090] Place 10 mg of CU, CU-Br, or CU-SH into a sealed 50 mL glass bottle. Inside the bottle, add a container containing 300 mg of Hg. 0 A 5mL bottle with an open cap was used. The device was sealed and heated at 140°C for 4 days to allow the adsorbent to react with Hg. 0 The adsorption reached saturation. Take 5 mg of adsorbed Hg. 0 The material was then placed in 5 mL of aqua regia, kept at 50°C for 12 hours, and then diluted. The Hg concentration in the solution was measured to calculate the effect of Cu-SH on Hg in air. 0 Steam removal efficiency.

[0091] Test results are as follows Figure 13 As shown, CU and CU-Br affect Hg 0 The vapor adsorption efficiency is extremely low, with an adsorption capacity of less than 5 mg / g. CU-SH has very low adsorption efficiency for Hg. 0 The steam exhibited high adsorption efficiency, with a saturated adsorption capacity of 289.7 mg / g.

[0092] (7) CU-SH for simulating Hg 2+ Hg in polluted drinking water 2+ removal

[0093] The experiment involved adding Hg to tap water. 2+ Standard solution, so that Hg 2+ A concentration of 0.5 mg / g was used to simulate Hg contamination in drinking water, and the main Na+ in the solution was detected by ICP-MS. + K + Ca 2+ Ma 2+ Zn 2+ The concentrations of major metal cations were determined. 10 mg of Cu-SH was added to 50 mL of simulated Hg. 2+ Na+ was measured in contaminated tap water after adsorption by vibration at 200 rpm for 1 hour at room temperature. + K + Ca 2+ Ma 2+ Zn 2+ and Hg 2+ The concentration.

[0094] Test results are as follows Figure 14 As shown, after CU-SH treatment, the Na+ in tap water... + K + The ion concentration did not change significantly, Ca 2+ Ma 2+ Zn 2+ The concentration decreased slightly, while the highly toxic Hg... 2+The concentration decreased significantly from 0.5 mg / L to 0.0018 mg / L, indicating that CU-SH can be used for emergency treatment of contaminated Hg. 2+ Rapid treatment of contaminated drinking water to meet standards.

[0095] (8) Cu-SH adsorption of Hg 2+ Regenerative testing

[0096] The test conditions were as follows: 10 mg of CU-SH was added to 50 mL of solution with a concentration of 10 mg / L Hg. 2+ In aqueous solution, the pH was adjusted to 5.0 ± 0.05 using 1 mol / L nitric acid and 1 mol / L sodium hydroxide, and adsorption was performed at 200 rpm for 1 h at room temperature. Centrifugation was used to separate the solid and liquid phases, and the Hg concentration in the supernatant was measured to calculate the removal rate. The solid was collected and 10 mL of 0.1 mol / L hydrochloric acid solution (1% thiourea concentration) was added. After desorption at room temperature for 1 h, centrifugation was performed, and the solid was collected, washed with deionized water, and used for further Hg removal. 2+ Adsorption was performed, and this cycle was repeated 20 times. The solid was collected, and the changes in the microstructure and chemical composition of CU-SH were detected by SEM and XPS.

[0097] Test results are as follows Figure 15 As shown, CU-SH affects Hg 2+ It exhibits extremely high long-lasting removal efficacy; after 20 cycles of use, it effectively removes Hg. 2+ The removal rate remained above 95%. SEM images showed that CU-SH maintained a fibrous structure after 20 regenerations, indicating that the physical structure of CU-SH was stable. EDS spectroscopy showed that the regenerated CU-SH was mainly composed of C, O, and S, which were uniformly distributed, with no obvious Hg, indicating that Hg was successfully desorbed. Figure 16 XPS energy dispersive spectroscopy (EDS) analysis showed results consistent with EDS. XPS S2p fine structure spectroscopy revealed that sulfur primarily exists in the -SH form, with no characteristic peaks observed for SS or oxidized S, indicating that Cu-SH possesses good chemical stability. Figure 17 ).

[0098] Finally, it should be noted that the above embodiments of the present invention are merely illustrative examples and not intended to limit the implementation of the invention. Those skilled in the art can make other variations and modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of this invention are still within the scope of protection of this invention.

Claims

1. A method for preparing an adsorbent material for efficient mercury removal, characterized in that, Defatted cellulose is added to an organic solution containing bromine acetyl bromide to bromate the cellulose, thus obtaining brominated cellulose; Then, under nitrogen protection, cellulose bromide and sodium hydrosulfide are reacted to thiolize the cellulose bromide, thereby obtaining the adsorbent material; specifically, the following steps are included: (1) The cellulose was cut into pieces and ultrasonically washed in anhydrous ethanol to remove impurities. After vacuum drying, defatted cellulose was obtained. (2) Defatted cellulose is added to an organic solution containing bromoacetyl bromide, and the mixture is stirred at 25-60 °C for 24-72 h. The mixture is then filtered, washed with anhydrous ethanol, and dried to obtain brominated cellulose. The volume fraction of bromoacetyl bromide in the organic solution is 1-5%. (3) Under nitrogen protection, cellulose bromide and sodium hydrosulfide are added to anhydrous ethanol and stirred at 60~90 °C for 24~96 h. The mixture is then filtered and washed with water or ethanol and dried to obtain the adsorbent material. The mass ratio of cellulose bromide to sodium hydrosulfide is 1:3~1:

7.

2. The method for preparing a highly efficient mercury removal adsorbent material according to claim 1, characterized in that, The cellulose is one of lignocellulose and cotton cellulose.

3. The method for preparing a highly efficient mercury removal adsorbent material according to claim 2, characterized in that, The cellulose is cotton cellulose.

4. The method for preparing a highly efficient mercury removal adsorbent material according to claim 1, characterized in that, The organic solution is obtained by dissolving bromoacetyl bromide in an organic solvent; the organic solvent is one or more of N,N-dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide.

5. The method for preparing a highly efficient mercury removal adsorbent material according to claim 4, characterized in that, The organic solvent is N,N-dimethylformamide.

6. The method for preparing a highly efficient mercury removal adsorbent material according to claim 4, characterized in that, In step (2), the mass-volume ratio of defatted cellulose to organic solution is 1 g: 50~150 mL.

7. An adsorbent material for highly efficient removal of mercury, characterized in that, It was prepared using the method described in any one of claims 1 to 6 for preparing an adsorbent material that efficiently removes mercury.

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