A composite adsorption material for uranium-containing wastewater and a preparation method thereof
By treating wood flour with alkali and loading it with HAP, a multi-level composite adsorbent material was constructed, which solved the problem of decreased adsorption performance of existing materials under acidic conditions and achieved efficient and stable uranium ion removal.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUHAN TEXTILE UNIV
- Filing Date
- 2026-03-27
- Publication Date
- 2026-06-02
Smart Images
Figure CN122124753A_ABST
Abstract
Description
Technical Field
[0001] This invention discloses a composite adsorbent material for uranium-containing wastewater and its preparation method, belonging to the field of wastewater treatment technology. Background Technology
[0002] With the rapid development of the nuclear energy industry, large quantities of uranium-containing acidic wastewater are generated during uranium mining, nuclear fuel processing, and nuclear facility operation. Uranium, a heavy metal element with radioactivity and chemical toxicity, not only pollutes the ecological environment when it enters aquatic bodies but also poses a potential threat to human health through bioaccumulation in the food chain. Furthermore, the discharge of untreated uranium-containing wastewater also wastes uranium resources. Therefore, achieving efficient treatment and recycling of uranium-containing wastewater has become an important research direction in the field of environmental protection.
[0003] Currently, methods for treating uranium-containing wastewater include chemical precipitation, ion exchange, membrane separation, and adsorption. Among these, adsorption is considered one of the most promising technologies due to its simple operation, low cost, wide availability of adsorbents, and the renewability of some materials. The adsorbent, as the core material in the adsorption process, is crucial for efficient uranium adsorption. Existing adsorbent materials mainly include inorganic, organic, and composite adsorbents. Inorganic mineral materials often suffer from problems such as easy particle aggregation and insufficient exposure of effective adsorption sites, thus limiting their practical application performance. Organic adsorbents have tunable structures, but under acidic conditions, their surface functional groups undergo protonation, leading to a significant reduction in their coordination ability for uranium. To combine the structural advantages of organic materials with the efficient uranium adsorption characteristics of inorganic materials, constructing organic-inorganic composite adsorbents is of great significance for improving the treatment efficiency of wastewater containing radionuclides.
[0004] Biomass materials, especially lignocellulose materials, have become important substrates for adsorption materials due to their wide availability, renewability, environmental friendliness, and low cost. Wood flour, with its hierarchical porous structure and abundant oxygen-containing functional groups such as hydroxyl groups, shows potential in the adsorption of heavy metal ions. However, the uranium adsorption capacity of natural wood flour is limited, and its selectivity for uranium ions is insufficient, making it difficult to directly meet the needs of practical uranium-containing wastewater treatment. Therefore, functional modification is usually required.
[0005] Hydroxyapatite (HAP) has a unique crystal structure and abundant active sites, which gives it a strong adsorption selectivity for uranium ions. It can selectively adsorb uranium ions through ion exchange, surface complexation and other processes. However, in practical applications, nano-HAP is prone to agglomeration, which leads to problems such as the embedding of active sites, poor particle dispersibility, poor sedimentation performance and difficulty in recycling. Summary of the Invention
[0006] The technical problem to be solved by the present invention is to provide a composite adsorption material for uranium-containing wastewater that combines high adsorption capacity and good structural stability, and a method for preparing the same.
[0007] This invention involves alkali treatment of natural wood flour and further modification of the alkali-treated wood flour to uniformly load HAP onto its surface, enabling efficient removal of radioactive uranium ions over a wide pH range (3–9), thereby improving adsorption efficiency and the practical application performance of the material.
[0008] Raw materials involved in the method of this invention:
[0009] Wood flour, sodium hydroxide, sodium alginate, anhydrous calcium chloride, sodium dihydrogen phosphate dihydrate, ammonia, and deionized water.
[0010] The preparation method of the composite adsorbent material for uranium-containing wastewater of the present invention includes the following steps:
[0011] 1) Add wood flour to sodium hydroxide solution and perform alkali treatment under heating and stirring conditions. After treatment, wash repeatedly with deionized water until neutral to obtain alkali-treated wood flour.
[0012] 2) Mix thoroughly with sodium alginate solution, let stand for a certain period of time, then centrifuge and discard the supernatant;
[0013] 3) First, add half the volume of deionized water to the sodium alginate solution in step 2). While stirring, add anhydrous calcium chloride solution to the solution to allow the sodium alginate to undergo ion exchange cross-linking to form a calcium alginate structure. After standing, remove the supernatant.
[0014] 4) Repeat steps 2) and 3) 2-3 times to enhance the binding between wood flour and calcium alginate, then wash with deionized water until neutral;
[0015] 5) Add anhydrous calcium chloride solution to the sample obtained above, and slowly add sodium dihydrogen phosphate dihydrate solution under stirring, and mix thoroughly;
[0016] 6) Add ammonia to the mixed system to adjust the pH of the solution to alkaline conditions, stir the reaction at room temperature and allow it to stand for aging. After the reaction is complete, wash until neutral and dry to obtain the adsorbent material.
[0017] Some preferred experimental conditions are as follows:
[0018] The alkali treatment in step 1) is carried out at a heating temperature of 80 °C for 2 h. The solid-liquid ratio of wood flour to sodium hydroxide solution is 1:50 g / mL (m:v), and the concentration of sodium hydroxide solution is 5 wt%.
[0019] In steps 2) and 3), the solid-liquid ratio of the alkali-treated wood flour to the sodium alginate solution and the anhydrous calcium chloride solution is 1:20 g / mL (m:v), the sodium alginate concentration is 10 wt%, the anhydrous calcium chloride concentration is 1 mol / L, and the volume ratio of the sodium alginate solution to the anhydrous calcium chloride solution is 2:1.
[0020] In step 5), the concentration of anhydrous calcium chloride is 0.5 mol / L, the concentration of sodium dihydrogen phosphate dihydrate is 0.3 mol / L, the Ca / P ratio is 1.67, and the solid-liquid ratio of the sample prepared in the previous step to the mixed solution is 1:20 g / mL (m:v).
[0021] The pH of the mixture described in step 6) was adjusted to 10, and after stirring at room temperature for 1 h, it was allowed to stand for 24 h to age.
[0022] This invention first involves alkali treatment of poplar wood powder to remove some impurities and improve its surface structure, thereby exposing more hydroxyl groups on the material surface. This treatment step not only improves the surface reactivity and interfacial bonding ability of the wood powder, providing more anchor points for the subsequent loading of functional components, but also addresses the problem of insufficient adsorption active sites in the original wood powder, providing a structural basis for constructing a stable composite system.
[0023] This invention introduces sodium alginate during the composite material preparation process, which forms a three-dimensional cross-linked network structure under the action of calcium ions. This sodium alginate network structure serves to confine and fix the hydroxyapatite, effectively controlling its in-situ formation on the fiber surface, limiting its local aggregation, and ensuring its uniform dispersion on the wood flour surface. Therefore, it avoids the problem of active sites being buried or reduced utilization due to aggregation of inorganic nanomaterials, thereby improving the availability of hydroxyapatite functional components in the composite material.
[0024] This invention constructs a multi-level structure of "biomass skeleton—polymer network—inorganic functional components," enabling synergistic effects among the components in the composite system. This ensures structural stability while improving the effective utilization rate of functional components such as hydroxyapatite, thus achieving high adsorption capacity and good structural stability. Simultaneously, this structure improves the material's adsorption performance under typical acidic conditions (pH≈3), thereby enhancing its practical applicability in acidic uranium-containing wastewater. Existing uranium adsorbents generally exhibit decreased adsorption performance under strongly acidic conditions, and their structures are easily damaged. Therefore, when treating acidic uranium-containing wastewater, existing adsorbents often struggle to maintain structural stability while preserving high adsorption efficiency, thus limiting their practical application.
[0025] According to another aspect of the present invention, an application of a uranium adsorbent material in the treatment of uranium-containing wastewater is provided, comprising: oscillating the adsorbent material and the uranium-containing wastewater at a certain constant temperature, so that uranium ions in the radioactive wastewater undergo an adsorption reaction with the adsorbent material.
[0026] The solid-liquid ratio of the adsorbent material to the uranium-containing wastewater was 1:2 (g / L); the temperature was 35 ℃; and the adsorption reaction time was 12 h.
[0027] The beneficial effects of this invention are as follows:
[0028] 1) By treating wood flour with alkali, a sodium alginate-calcium network is introduced to facilitate the in-situ loading of hydroxyapatite functional components, thereby constructing a uranium adsorption composite material that can efficiently adsorb uranium ions in acidic uranium-containing wastewater.
[0029] 2) This invention uses natural materials such as poplar powder as the base raw materials. The preparation process is mild and simple, avoiding complex chemical modification and high-cost raw materials, which is conducive to large-scale preparation and engineering application promotion.
[0030] 3) The in-situ loading of hydroxyapatite components through the calcium alginate cross-linking network is beneficial to the uniform dispersion of hydroxyapatite in the wood flour matrix, improves the accessibility of effective adsorption sites, and thus enhances the actual adsorption efficiency of the material.
[0031] 4) The composite material prepared by this invention can still maintain a high adsorption capacity of uranium ions in an acidic environment with a pH of about 3, which overcomes the problem of the decline in adsorption performance of existing adsorption materials under strong acid conditions and improves its applicability in the actual treatment of acidic uranium-containing wastewater. Attached Figure Description
[0032] Figure 1 (a), (b), and (c) are SEM characterization spectra of the adsorbent material prepared in this invention at different magnifications;
[0033] Figure 2 This is the FTIR spectrum of the adsorption material prepared in this invention;
[0034] Figure 3 This is the XRD pattern of the adsorption material prepared in this invention;
[0035] Figure 4 This is the XPS spectrum of the adsorbent material prepared in this invention;
[0036] Figure 5 The W, AW, AW-HAP, AW-SA, and AW-SA-HAP prepared in this invention are effective against UO2. 2+ The amount of ions adsorbed. Detailed Implementation
[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.
[0038] Raw materials involved in the method of this invention:
[0039] Poplar wood powder, sodium hydroxide, sodium alginate, anhydrous calcium chloride, sodium dihydrogen phosphate dihydrate, ammonia, and deionized water.
[0040] The preparation method of the composite adsorbent material for uranium-containing wastewater of the present invention includes the following steps:
[0041] Wood flour was added to a sodium hydroxide solution and subjected to alkali treatment under heating and stirring conditions. After treatment, the wood flour was repeatedly washed with deionized water until neutral to obtain alkali-treated wood flour.
[0042] Mix thoroughly with sodium alginate solution, let stand for a certain period of time, then centrifuge and discard the supernatant;
[0043] First, add half the volume of deionized water to the sodium alginate solution in step 2). While stirring, add anhydrous calcium chloride solution to the solution to allow the sodium alginate to undergo ion exchange cross-linking and form a calcium alginate structure. After standing, remove the supernatant.
[0044] Repeat steps 2) and 3) 2-3 times to enhance the binding between wood flour and calcium alginate, then wash with deionized water until neutral;
[0045] Add anhydrous calcium chloride solution to the sample obtained above, and slowly add sodium dihydrogen phosphate dihydrate solution under stirring, and mix thoroughly.
[0046] Ammonia was added to the mixed system to adjust the pH of the solution to alkaline conditions. The mixture was stirred and allowed to stand for aging at room temperature. After the reaction was completed, the mixture was washed until neutral and dried to obtain the adsorbent material.
[0047] According to another aspect of the present invention, an application of a uranium adsorbent material in the treatment of uranium-containing wastewater is provided, comprising: oscillating the adsorbent material and the uranium-containing wastewater at a certain constant temperature, so that uranium ions in the radioactive wastewater undergo an adsorption reaction with the adsorbent material.
[0048] The solid-liquid ratio of the adsorbent material to the uranium-containing wastewater was 1:2 (g / L); the temperature was 35 ℃; and the adsorption reaction time was 12 h.
[0049] Example 1
[0050] Take 2 g of poplar powder sample and place it in 100 mL of 5 wt% sodium hydroxide solution. Mix thoroughly and stir at 80℃ for 2 h. Filter the sample and wash it with deionized water until neutral. Dry it in an oven. Take 0.5 g of the obtained alkali-treated sample and mix it thoroughly with 10 mL of 10 wt% sodium alginate solution. Let it stand for 30 min, centrifuge and discard the supernatant. Add 5 mL of deionized water and add the same volume of 1 mol / L anhydrous calcium chloride solution while stirring. Let it stand for 30 min and centrifuge to discard the supernatant. Repeat the above two steps 3 times. Finally, wash with deionized water until neutral. Add 5 mL of anhydrous calcium chloride solution and slowly add 0.3 mol / L sodium dihydrogen phosphate dihydrate solution while stirring. Adjust the pH of the solution to 10 with ammonia. Stir for 1 h and age at room temperature for 24 h. Wash it with deionized water and dry it at 65℃ for later use.
[0051] The prepared adsorbent material was used to adsorb and remove the radioactive nuclide UO2. 2+ The steps for ion determination are as follows: Take 30 mL of UO2 at different concentrations. 2+ An ionic solution (pH=5) with an adsorbent concentration of 0.5 g / L was prepared and placed in a benchtop constant-temperature shaking incubator at 180 rpm and 35 ℃. The equilibrium adsorption capacity (q) after 12 h of reaction was determined. e See Table 1:
[0052] Table 1. Removal of radioactive nuclide UO2 from water by wood flour-based composite adsorbent materials 2+ ion
[0053]
[0054] Detection method: After the sample was filtered through a 0.45 μm polyethersulfone membrane, the initial and residual UO2 in the solution after adsorption were detected using an inductively coupled plasma atomic emission spectrometer (Agilent 5800). 2+ Ion concentration.
[0055] Therefore, it can be seen that the wood powder-based composite adsorbent material has a strong adsorption performance for uranium ions, with a maximum adsorption capacity of 315.05 mg / g.
[0056] The adsorbent material was characterized by scanning electron microscopy (SEM), and the results are as follows: Figure 1 As shown, the surface of the modified wood flour-based composite adsorbent material is loaded with irregular particles, which are uniformly dispersed. Therefore, the introduction of sodium calcium alginate can reduce the agglomeration of hydroxyapatite and expose more adsorption active sites.
[0057] Sodium alginate (SA) contains a large number of carboxyl groups, which can react with UO2. 2+ Chelation occurs, and it can also occur in Ca 2+ Under the action of the agent, a typical three-dimensional "egg box" gel network is rapidly formed. This network structure can effectively fix and disperse nano-HAP particles, significantly inhibit their aggregation behavior, thereby increasing the available surface area of the material and exposing adsorption sites.
[0058] The wood flour-based composite adsorbent material was characterized by Fourier transform infrared spectroscopy (FTIR), and the results are as follows: Figure 2 As shown, the presence of characteristic absorption peaks related to hydroxyapatite and sodium calcium alginate in the FTIR spectrum indicates that the material was successfully prepared.
[0059] X-ray diffraction (XRD) analysis was performed on the wood flour-based composite adsorbent material, and the results are as follows: Figure 3 As shown, the characteristic peaks are mainly composed of lignocellulose and hydroxyapatite, which is consistent with the results obtained from infrared spectroscopy.
[0060] X-ray photoelectron spectroscopy (XPS) was used to analyze the adsorbent material, and the results are as follows: Figure 4 As shown, elements such as Ca, P, and C were indeed detected on the surface of the wood flour, further confirming that the material is a hydroxyapatite-sodium alginate-wood flour-based composite material.
[0061] Example 2
[0062] Material preparation is the same as in Example 1.
[0063] The prepared adsorbent material was used to adsorb and remove radioactive nuclide UO2 from water. 2+ Ions, the steps are as follows: Take 30 mL of UO2 at different pH values 2+ An ionic solution with an adsorbent concentration of 0.5 g / L and a pH range of 3–9 was prepared and placed in a benchtop constant-temperature shaking incubator at 180 rpm and 35 °C. The equilibrium adsorption capacity (q) after 12 h of reaction was determined. e See Table 2:
[0064] Table 2. Effects of wood flour-based composite adsorbents on UO2 at different pH values 2+ Ion removal rate
[0065]
[0066] Therefore, it can be concluded that within the pH range of 3-7, the wood flour-based composite adsorbent material effectively absorbs UO2. 2+ The adsorption effect of the ions was good, all greater than 116 mg / g; when the pH of the uranium-containing wastewater was 3, the adsorption material showed good adsorption of UO2. 2+ The material exhibits the highest ion equilibrium adsorption capacity, reaching 195.89 mg / g, indicating that it still possesses excellent adsorption performance under acidic conditions.
[0067] Example 3
[0068] Material preparation is the same as in Example 1.
[0069] The prepared adsorbent material was used to adsorb and remove radioactive nuclide UO2 from water. 2+ The steps for ion determination are as follows: Take 30 mL of UO2 with a concentration of 150 ppm. 2+ An ionic solution (pH=5) with an adsorbent concentration of 0.5 g / L was prepared and placed in a benchtop constant-temperature shaking incubator at 180 rpm and 35 ℃. The reaction time ranged from 10 to 480 min, and the equilibrium adsorption capacity (q) at different reaction time points was recorded. e See Table 3:
[0070] Table 3. Effects of wood flour-based composite adsorbents on UO2 at different adsorption times. 2+ Ion removal rate
[0071]
[0072] Detection method: Same as in Example 1.
[0073] Therefore, it can be concluded that the wood flour-based composite adsorbent material effectively adsorbs UO2 within the first 30 minutes. 2+ The adsorption rate of ions is relatively fast, reaching 75.6% of the equilibrium adsorption capacity, and essentially reaching adsorption equilibrium within 240 minutes. This indicates that the adsorbent material effectively adsorbs UO2 in aqueous solution. 2+ Ions have a relatively fast adsorption rate.
[0074] Example 4
[0075] 2 g of poplar wood powder (W) was added to 100 mL of 5 wt% sodium hydroxide solution and mixed. The mixture was stirred and reacted at 80 °C for 2 h. After the reaction was complete, the mixture was washed with deionized water until neutral and then dried in an oven at 65 °C. The resulting sample was alkali-treated wood powder (AW).
[0076] 0.5 g of alkali-treated wood flour was added to 5 mL of 0.5 mol / L anhydrous calcium chloride solution. While stirring, 5 mL of 0.3 mol / L sodium dihydrogen phosphate dihydrate solution was slowly added to maintain the Ca / P ratio of the solution at 1.67. The pH of the solution was adjusted to 10 using concentrated ammonia. The mixture was then stirred at room temperature for 1 h, allowed to stand for 24 h to age, filtered, washed with deionized water until neutral, and dried completely at 65 °C. The resulting sample was AW-HAP.
[0077] Take 0.5 g of the obtained alkali-treated wood flour and mix it thoroughly with 10 mL of 10 wt% sodium alginate solution. Let it stand for 30 min, centrifuge and discard the supernatant. Add 5 mL of deionized water and then add the same volume of 1 mol / L anhydrous calcium chloride solution while stirring. Let it stand for 30 min and centrifuge to discard the supernatant. Repeat the above two steps 3 times. Finally, wash with deionized water until neutral and dry completely in an oven at 65 ℃. The resulting sample is AW-SA.
[0078] Take 0.5 g of alkali-treated wood flour, add 10 mL of 10 wt% sodium alginate solution, mix thoroughly, let stand for 30 min, centrifuge and discard the supernatant, add 5 mL of deionized water, and then add the same volume of 1 mol / L anhydrous calcium chloride solution while stirring. Let stand for 30 min, centrifuge and discard the supernatant. Repeat the above two steps 3 times. Finally, wash with deionized water until neutral. Add 5 mL of anhydrous calcium chloride solution, and slowly add 0.3 mol / L sodium dihydrogen phosphate dihydrate solution while stirring. Adjust the pH of the solution to 10 with ammonia water, stir for 1 h, and then age at room temperature for 24 h. After washing with deionized water and drying at 65 ℃, the resulting sample is AW-SA-HAP.
[0079] The different adsorbent materials prepared above were used to adsorb and remove radioactive nuclide UO2 from water. 2+ Ions, compare their effects on UO2 2+ The adsorption performance of ions was determined by the following steps: Take 30 mL of UO2 with a concentration of 100 ppm. 2+ An ionic solution (pH=5.5) with an adsorbent concentration of 0.5 g / L was prepared and placed in a benchtop constant-temperature shaking incubator at 180 rpm and 35 ℃. The reaction time was 12 h. The adsorption capacity (q) of different materials was measured. e )See Figure 5 .
[0080] Detection method: Same as in Example 1.
[0081] Therefore, under the same conditions, the UO2 of raw wood flour (W) 2+ The ion adsorption capacity was 34.50 mg / g. After alkali treatment, the adsorption capacity of the sample (AW) was 76.61 mg / g, which was twice that of W. The adsorption capacities of AW-HAP and AW-SA were also significantly increased compared to AW, at 124.71 mg / g and 164.28 mg / g, respectively. The adsorption capacity of AW-SA-HAP, a hydroxyapatite-based in-situ dispersed hydroxyapatite, for UO2 was [not specified]. 2+Ion adsorption showed the best effect, with an adsorption capacity of 191.13 mg / g, which is about 6 times that of the original wood flour. Compared with the original wood flour, the AW-SA-HAP composite material significantly improved its adsorption capacity for UO2. 2+ Adsorption properties of ions.
[0082] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a composite adsorbent material for uranium-containing wastewater, characterized in that, Includes the following steps: 1) Add wood flour to sodium hydroxide solution and perform alkali treatment under heating and stirring conditions. After treatment, wash repeatedly with deionized water until neutral to obtain alkali-treated wood flour. 2) Mix thoroughly with sodium alginate solution, let stand for a certain period of time, then centrifuge and discard the supernatant; 3) First, add half the volume of deionized water to the sodium alginate solution in step 2). While stirring, add anhydrous calcium chloride solution to the solution to allow the sodium alginate to undergo ion exchange cross-linking to form a calcium alginate structure. After standing, remove the supernatant. 4) Repeat steps 2) and 3) 2-3 times to enhance the binding between wood flour and calcium alginate, then wash with deionized water until neutral; 5) Add anhydrous calcium chloride solution to the sample obtained above, and slowly add sodium dihydrogen phosphate dihydrate solution under stirring, and mix thoroughly; 6) Add ammonia to the mixed system to adjust the pH of the solution to alkaline conditions, stir the reaction at room temperature and allow it to stand for aging. After the reaction is complete, wash until neutral and dry to obtain the adsorbent material.
2. The preparation method according to claim 1, characterized in that: The heating temperature for the alkali treatment in step 1) is 80℃, and the treatment time is 2 h; the solid-liquid ratio of wood flour to sodium hydroxide solution is 1:50 g / mL, and the concentration of sodium hydroxide solution is 5wt%.
3. The preparation method according to claim 1, characterized in that: In steps 2) and 3), the solid-liquid ratio of the alkali-treated wood flour to the sodium alginate solution and the anhydrous calcium chloride solution is 1:20 g / mL, the sodium alginate concentration is 10 wt%, the anhydrous calcium chloride concentration is 1 mol / L, and the volume ratio of the sodium alginate solution to the anhydrous calcium chloride solution is 2:
1.
4. The preparation method according to claim 1, characterized in that: In step 5), the concentration of anhydrous calcium chloride is 0.5 mol / L, the concentration of sodium dihydrogen phosphate dihydrate is 0.3 mol / L, the Ca / P ratio is 1.67, and the solid-liquid ratio of the sample prepared in the previous step to the mixed solution is 1:20 g / mL (m:v).
5. The preparation method according to claim 1, characterized in that: The pH of the mixture described in step 6) was adjusted to 10, and after stirring at room temperature for 1 h, it was allowed to stand for 24 h to age.
6. A composite adsorbent material for uranium-containing wastewater, the preparation method of which is as described in claim 1.
7. The application of the composite adsorbent material according to claim 6 in the treatment of uranium-containing wastewater.
8. The application according to claim 7, characterized in that, The composite adsorbent material and uranium-containing wastewater were oscillated at a constant temperature to allow uranium ions in the radioactive wastewater to undergo an adsorption reaction with the adsorbent material. The solid-liquid ratio of the adsorbent material to the uranium-containing wastewater was 1:2 (g / L); the temperature was 35 °C; and the adsorption reaction time was 12 h.