A nano zero-valent iron loaded nickel-cobalt layered double hydroxide composite material, a preparation method and application thereof
By preparing a nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material, the problems of easy agglomeration and oxidation of nano-zero-valent iron were solved, and the simultaneous and efficient removal of hexavalent uranium and tetracycline from water was achieved, with good stability and operability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANHUA UNIV
- Filing Date
- 2026-05-28
- Publication Date
- 2026-07-07
Smart Images
Figure CN122344031A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of environmental functional materials, specifically relating to a nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material, its preparation method, and its application. Background Technology
[0002] Uranium and tetracycline (TC) are pollutants with high mobility and potential ecological risks in aquatic environments. Uranium typically exists as uranyl ions (U(VI)) or their complexes, exhibiting strong water-phase migration capabilities. TC, as a typical antibiotic pollutant, contains multiple oxygen- and nitrogen-containing functional groups in its molecular structure, enabling it to complex with metal ions or mineral surfaces through hydrogen bonding and electrostatic interactions. When both coexist in the same water body, they may form a complex pollution system, altering their respective migration and removal behaviors through complexation, competitive adsorption, or interfacial reactions. Currently, treatment methods for uranium- or antibiotic-containing wastewater mainly include adsorption, chemical precipitation, membrane separation, advanced oxidation, biological treatment, and reduction fixation. Among these, adsorption has received widespread attention due to its mild reaction conditions, customizable material structures, and suitability for removing low-concentration pollutants. However, traditional adsorption materials are usually designed for single pollutants and are easily affected by competitive adsorption, complexation reactions, and interference from coexisting ions in uranium and tetracycline coexisting systems, making it difficult to achieve efficient removal of both simultaneously.
[0003] Nano-zero valent iron (nZVI) possesses strong reducing activity and electron-donating capacity, making it suitable for the reduction, transformation, and fixation of various oxidized pollutants. However, nZVI particles are prone to aggregation, oxidation, and surface passivation in water, leading to a decrease in effective specific surface area, reduced reactivity, and insufficient stability. Therefore, there is an urgent need to develop a structurally stable composite material with abundant active sites that can mitigate the aggregation and passivation problems of nano-zero valent iron for the removal of pollutants such as hexavalent uranium and tetracycline in water bodies. Summary of the Invention
[0004] This invention provides a nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material, its preparation method, and its application. It aims to solve the problems of easy agglomeration, easy oxidation and passivation, low utilization of active sites, and difficulty in simultaneous and efficient removal of U(VI) and TC by traditional adsorption materials.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material, wherein the composite material is composed of nano-zero-valent iron supported on the surface of nickel-cobalt layered double hydroxide nanosheets.
[0006] Furthermore, the preparation method of the composite material includes the following steps: S1. Add the water-soluble polymeric dispersant to ultrapure water and stir to disperse at room temperature to obtain a polymeric dispersion. S2. Add cobalt salt and nickel salt to ultrapure water and stir to dissolve at room temperature to obtain Ni-containing... 2+ and Co 2+ Metal salt solutions; S3. Slowly add the polymer dispersion to the metal salt solution and continue stirring; then add dilute ammonia dropwise to form a NiCo-LDH precursor mixture; S4. The precursor mixture is hydrothermally reacted at 60-120°C for 12-36 h; after natural cooling to room temperature, the product is centrifuged, washed and vacuum dried to obtain NiCo-LDH nanosheets. S5. The NiCo-LDH nanosheets and ferrous salt are added to ultrapure water and dispersed by stirring under an inert atmosphere to obtain a mixture containing NiCo-LDH and Fe. 2+ A homogeneous suspension; S6. Under an inert atmosphere and with vigorous stirring, sodium borohydride solution is added dropwise to the suspension, causing Fe... 2+ In-situ reduction to generate nano-zero valent iron, which is then loaded onto the surface of NiCo-LDH nanosheets; S7. After the reaction is complete, the solid product is collected by centrifugation and washed with ultrapure water; then it is frozen and freeze-dried to obtain a nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material.
[0007] Technical principle of the solution: Layered double hydroxide (LDH) materials possess a layered structure, a large surface contact area, and tunable metal sites, making them suitable as a loading carrier for nZVI and improving the dispersibility and stability of nZVI particles. Nickel-cobalt layered double hydroxide (NiCo-LDH) nanosheets have a good layered structure and surface active sites, providing adsorption and coordination sites for pollutants. Loading nZVI onto the surface of NiCo-LDH nanosheets allows for the simultaneous utilization of nZVI's reduction and fixation capabilities and NiCo-LDH's adsorption, coordination, and carrier dispersion effects, thereby enhancing the material's ability to simultaneously remove coexisting U(VI) and TC pollutants.
[0008] Furthermore, in step S1, the water-soluble polymeric dispersant is carboxymethyl cellulose, sodium carboxymethyl cellulose, or sodium alginate.
[0009] Through the above settings, the water-soluble polymeric dispersant can improve the dispersion state of metal ions in the aqueous system and play a certain stabilizing and structural regulation role in the formation of NiCo-LDH nanosheets, which is conducive to obtaining NiCo-LDH nanosheet carriers with better dispersibility, thus providing a basis for the uniform loading of nZVI in the future.
[0010] Furthermore, in step S2, the nickel salt is nickel acetate, nickel nitrate, nickel chloride, or nickel sulfate; and the cobalt salt is cobalt acetate, cobalt nitrate, cobalt chloride, or cobalt sulfate.
[0011] Furthermore, in step S2, the molar ratio of the nickel salt to the cobalt salt is 1:0.5 to 1:2.
[0012] Furthermore, the hydrothermal reaction temperature in step S4 is 60–120°C, and the reaction time is 12–36 h.
[0013] By setting the parameters as described above, the temperature and reaction time of the hydrothermal reaction are controlled within a reasonable range, which is beneficial for forming layered double hydroxide nanosheets with stable structure and relatively uniform morphology.
[0014] Furthermore, in steps S5 and S6, the inert gas is nitrogen or argon.
[0015] Furthermore, in step S5, the ferrous salt is ferrous sulfate, ferrous chloride, or ferrous nitrate.
[0016] Furthermore, in step S5, the concentration of the ferrous salt solution is 0.02–0.06 M.
[0017] The above settings allow for the control of the loading of nano-zero valent iron on the surface of NiCo-LDH nanosheets. When the ferrous salt concentration is too low, the amount of nZVI iron generated is insufficient, which may result in limited reduction activity and pollutant removal capacity; when the ferrous salt concentration is too high, it is easy to cause nZVI particle aggregation or uneven loading.
[0018] Furthermore, in step S6, the concentration of the sodium borohydride solution is 0.01–0.2 mol / L.
[0019] Another technical solution provided by the present invention is to use the nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material described in any of the above claims to remove U(VI) and TC pollutants from water.
[0020] Compared with existing technologies, the beneficial effects of this solution are: 1. This method prepares a two-dimensional layered double hydroxide-supported zero-valent metal composite material. NiCo-LDH nanosheets not only serve as a carrier, but also effectively disperse nano-zero-valent iron (nZVI) particles using their two-dimensional layered structure and high specific surface area. Through in-situ reduction, nZVI is tightly anchored to the LDH surface, significantly suppressing the inherent defects of nZVI, such as easy aggregation, oxidation, and surface passivation. Simultaneously, NiCo-LDH itself is rich in surface metal active sites, enabling efficient capture of tetracycline (TC) molecules through hydrogen bonding, coordination, and electrostatic adsorption. Meanwhile, nZVI possesses strong reducing power, reducing highly mobile hexavalent uranium (U(VI)) to less mobile U(IV). Therefore, this composite material achieves a multi-coupling mechanism of "NiCo-LDH adsorption / coordination of TC and U(VI), and nZVI reduction and fixation of U(VI)," successfully solving the technical challenge of simultaneously removing coexisting pollutants of U(VI) and TC using traditional single-functional materials, and avoiding competitive adsorption interference between pollutants in the coexisting system.
[0021] 2. The preparation method of this invention has a reasonable process design, mild and easily controllable conditions, and good operability and repeatability. In the NiCo-LDH synthesis stage, by introducing a water-soluble polymeric dispersant and precisely controlling the hydrothermal reaction temperature and time, as well as the molar ratio of nickel and cobalt salts, NiCo-LDH nanosheet carriers with uniform morphology, complete layered structure, and good dispersibility can be prepared. In the subsequent nZVI loading stage, by adjusting the concentration of ferrous salt and sodium borohydride reducing agent, the amount and size distribution of nZVI particles can be effectively controlled, avoiding agglomeration or uneven loading caused by excessive iron content. Furthermore, an inert atmosphere is used in the preparation process to prevent the oxidation of Fe²⁺ and newly formed nZVI, and freeze-drying is used instead of high-temperature drying in the final product treatment, maximizing the preservation of the zero valence state and high reactivity of nZVI and reducing the risk of oxidation and structural collapse during the drying process. These technical features in the preparation process together ensure the stability of the composite material's performance between batches.
[0022] 3. The composite material prepared by this invention fully utilizes the reduction and fixation ability of nZVI and the adsorption, coordination and carrier dispersion effects of NiCo-LDH, overcoming the bottlenecks of existing nano zero-valent iron materials that are prone to agglomeration and passivation, have low utilization of active sites, and are difficult to remove coexisting pollutants of U(VI) and TC simultaneously and efficiently. It provides a new type of environmental functional material that is efficient, stable and has practical value for the purification of water bodies containing uranium and antibiotics. Attached Figure Description
[0023] Figure 1 This is the XRD pattern of the NC-nZVI composite material prepared in Example 2 of this invention; Figure 2 This is a transmission electron microscope image of the NC-nZVI composite material prepared in Example 2 of the present invention; Figure 3 This is the infrared (FT-IR) spectrum of the NC-nZVI composite material prepared in Example 2 of this invention after adsorbing uranium; Figure 4 This is a kinetic diagram of the synergistic removal of U(VI) and TC by the NC-nZVI composite material prepared in Example 2 of the present invention. Detailed Implementation
[0024] The present invention will be further described in detail below through specific embodiments: Example
[0025] A method for preparing a nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material is disclosed. The preparation method is as follows: 20 mg of carboxymethyl cellulose is added to 20 mL of ultrapure water and stirred and dispersed at room temperature to obtain a polymer dispersion. 1 mmol of nickel chloride and 0.5 mmol of cobalt chloride are added to 20 mL of ultrapure water and stirred and dissolved at room temperature to obtain a Ni-containing composite material. 2+ and Co 2+ A metal salt solution was prepared, with a molar ratio of nickel salt to cobalt salt of 1:0.5. The obtained polymer dispersion was slowly added to the metal salt solution, and stirring was continued for 30 min. Dilute ammonia was added dropwise under continuous stirring to form a NiCo-LDH precursor mixture. The obtained NiCo-LDH precursor mixture was transferred to a polytetrafluoroethylene-lined reactor and hydrothermally reacted at 60 °C for 36 h. After the reaction, the mixture was allowed to cool naturally to room temperature. The resulting product was centrifuged at 8000 rpm for 3 min and washed several times with ultrapure water. Finally, the washed product was vacuum dried at 80 °C for 8 h to obtain NiCo-LDH nanosheets.
[0026] 50 mg of the obtained NiCo-LDH nanosheets were added to 50 mL of a 0.02 M ferrous sulfate solution and dispersed under a nitrogen atmosphere by stirring, yielding a product containing NiCo-LDH and Fe. 2+ A homogeneous suspension was formed. Under a nitrogen atmosphere, the mixture was vigorously stirred, and 50 mL of a freshly prepared 0.01 mol / L sodium borohydride solution was added dropwise to the suspension to reduce Fe²⁺ in situ to generate nano-zero valent iron, which was then loaded onto the surface of NiCo-LDH nanosheets. After the reaction was complete, the resulting solid product was collected by centrifugation at 8000 rpm for 3 min and washed three times with ultrapure water using a continuous washing-centrifugation cycle. Finally, the precipitate was frozen for 8 h and freeze-dried for 20 h to obtain the NC-nZVI composite material. Example
[0027] A method for preparing a nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material is disclosed as follows: 20 mg of sodium alginate (SA) is dissolved in 20 mL of ultrapure water and stirred at 800 rpm for 15 min at room temperature to obtain a polymer dispersion. Simultaneously, 1 mmol of cobalt acetate and 1 mmol of nickel acetate are dissolved in 20 mL of ultrapure water and stirred under the same conditions. The polymer dispersion is then slowly added to the nickel-cobalt salt solution and stirred for 30 min. Next, dilute ammonia is added dropwise under continuous stirring for 15 min to obtain a NiCo-LDH precursor mixture. The NiCo-LDH precursor mixture is transferred to a polytetrafluoroethylene-lined reactor and reacted at 80 °C for 24 h. After the reaction, the mixture is allowed to cool naturally to room temperature, and the resulting product is centrifuged at 9000 rpm for 3 min and washed several times. Finally, the washed product is vacuum-dried at 60 °C for 12 h to obtain NiCo-LDH nanosheets.
[0028] A 0.04 M ferrous sulfate solution and 50 mg NiCo-LDH nanosheets were dispersed in 50 mL of ultrapure water and stirred continuously for 2 h under a nitrogen atmosphere to obtain a homogeneous suspension. Then, under vigorous stirring, 50 mL of freshly prepared 0.1 mol / L sodium borohydride solution was added dropwise to the suspension, and the reaction was continued for 8 h. After the reaction was complete, the resulting solid product was collected by centrifugation at 9000 rpm for 3 min and washed three times with ultrapure water using a continuous wash-centrifugation cycle. Finally, the precipitate was frozen for 7 h and freeze-dried for 24 h to obtain the NC-nZVI composite material.
[0029] The performance evaluation method for the simultaneous removal of U(VI) and TC in the NC-nZVI composite material prepared in this embodiment is as follows: 10 mg of NC-nZVI composite material was weighed as the adsorbent and added to 100 mL of simulated wastewater containing U(VI) and TC, with an initial U(VI) concentration of 60 mg / L and an initial TC concentration of 20 mg / L. The pH of the system was adjusted to 5 using 0.05 M HCl solution and 0.05 M NaOH solution. Subsequently, a stirred adsorption experiment was conducted at room temperature, with samples taken at preset time intervals, each time extracting 1.5–3.5 mL of the reaction solution. The resulting reaction solution was filtered through a filter membrane to remove adsorbent particles, and the uranium ion concentration in the filtrate was determined using ICP. Figure 1 It can be seen that the prepared NC-nZVI composite material exhibits characteristic diffraction peaks of both NiCo-LDH and nZVI, indicating that nZVI was successfully introduced into the NiCo-LDH system. Figure 2It is evident that nZVI particles are well dispersed and loaded on the surface of NiCo-LDH nanosheets, indicating that NiCo-LDH nanosheets can act as a carrier to disperse and anchor nZVI. Figure 3 As shown in the figure, a distinct O=U=O characteristic absorption peak appears, indicating that U(VI) is adsorbed or immobilized on the surface of the NC-nZVI composite material. Figure 4 As shown, in the U(VI) and TC coexistence system, the NC-nZVI composite material exhibits high removal efficiency for both U(VI) and TC, and can reach adsorption equilibrium in a short time. Example
[0030] A method for preparing a nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material is disclosed. The preparation method is as follows: 20 mg of sodium carboxymethyl cellulose is added to 20 mL of ultrapure water and stirred and dispersed at room temperature to obtain a polymer dispersion. 1 mmol of nickel nitrate and 1 mmol of cobalt nitrate are added to 20 mL of ultrapure water and stirred and dissolved at room temperature to obtain a Ni-containing composite material. 2+ and Co 2+ A metal salt solution was prepared, with a nickel-cobalt salt molar ratio of 1:1. The polymer dispersion was slowly added to the metal salt solution, and stirring was continued for 30 min. Subsequently, dilute ammonia was added dropwise under continuous stirring to obtain a NiCo-LDH precursor mixture. The obtained precursor mixture was transferred to a polytetrafluoroethylene-lined reactor and hydrothermally reacted at 80 °C for 24 h. After the reaction, the mixture was allowed to cool naturally to room temperature. The resulting product was centrifuged at 7000 rpm for 5 min and washed several times with ultrapure water. Finally, the washed product was vacuum dried at 65 °C for 10 h to obtain NiCo-LDH nanosheets.
[0031] 50 mg of NiCo-LDH nanosheets were added to 50 mL of a 0.03 M ferrous chloride solution and dispersed under an argon atmosphere by stirring, yielding a solution containing NiCo-LDH and Fe. 2+ A homogeneous suspension was formed. Under an argon atmosphere and with vigorous stirring, 50 mL of freshly prepared 0.1 mol / L sodium borohydride solution was added dropwise to the above suspension to allow Fe to form a homogeneous suspension. 2+ In-situ reduction of zero-valent iron nanoparticles was generated and loaded onto the surface of NiCo-LDH nanosheets. After the reaction, the resulting solid product was collected by centrifugation at 7000 rpm for 5 min and washed three times with ultrapure water through a continuous washing-centrifugation cycle. Finally, the precipitate was frozen for 10 h and freeze-dried for 18 h to obtain the NC-nZVI composite material. Example
[0032] A method for preparing a nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material is disclosed. The preparation method is as follows: 20 mg of sodium alginate is added to 20 mL of ultrapure water and stirred and dispersed at room temperature to obtain a polymer dispersion. 1 mmol of nickel sulfate and 2 mmol of cobalt sulfate are added to 20 mL of ultrapure water and stirred and dissolved at room temperature to obtain a Ni-containing composite material. 2+ and Co 2+ A metal salt solution was prepared, with a nickel-cobalt salt molar ratio of 1:2. The polymer dispersion was slowly added to the metal salt solution, and stirring was continued for 30 min. Subsequently, dilute ammonia was added dropwise under continuous stirring to obtain a NiCo-LDH precursor mixture. The obtained precursor mixture was transferred to a polytetrafluoroethylene-lined reactor and hydrothermally reacted at 120 °C for 12 h. After the reaction, the mixture was naturally cooled to room temperature, and the resulting product was centrifuged at 8000 rpm for 3 min and washed several times with ultrapure water. Finally, the washed product was vacuum dried at 50 °C for 8 h to obtain NiCo-LDH nanosheets.
[0033] 50 mg of NiCo-LDH nanosheets were added to 50 mL of a 0.06 M ferrous nitrate solution and dispersed under an argon atmosphere by stirring, yielding a solution containing NiCo-LDH and Fe. 2+ A homogeneous suspension was formed. Under an argon atmosphere and with vigorous stirring, 50 mL of freshly prepared 0.2 mol / L sodium borohydride solution was added dropwise to the above suspension to allow Fe to form a homogeneous suspension. 2+ In-situ reduction of zero-valent iron nanoparticles was generated and loaded onto the surface of NiCo-LDH nanosheets. After the reaction was complete, the resulting solid product was collected by centrifugation at 8000 rpm for 3 min and washed four times with ultrapure water through a continuous washing-centrifugation cycle. Finally, the precipitate was frozen for 10 h and freeze-dried for 15 h to obtain the NC-nZVI composite material.
[0034] The above are merely embodiments of the present invention, and common knowledge such as specific structures and / or characteristics in the solutions are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.
Claims
1. A nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material, characterized in that, The composite material is composed of nano-zero-valent iron loaded on the surface of nickel-cobalt layered double hydroxide nanosheets.
2. The nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material according to claim 1, characterized in that, The preparation method of the composite material includes the following steps: S1. Add the water-soluble polymeric dispersant to ultrapure water and stir to disperse at room temperature to obtain a polymeric dispersion. S2. Add cobalt salt and nickel salt to ultrapure water and stir to dissolve at room temperature to obtain Ni-containing... 2+ and Co 2+ Metal salt solutions; S3. Slowly add the polymer dispersion to the metal salt solution and continue stirring; then add dilute ammonia dropwise to form a NiCo-LDH precursor mixture; S4. The precursor mixture is hydrothermally reacted at 60-120°C for 12-36 h; after natural cooling to room temperature, the product is centrifuged, washed and vacuum dried to obtain NiCo-LDH nanosheets. S5. The NiCo-LDH nanosheets and ferrous salt are added to ultrapure water and dispersed by stirring under an inert atmosphere to obtain a mixture containing NiCo-LDH and Fe. 2+ A homogeneous suspension; S6. Under an inert atmosphere and with vigorous stirring, sodium borohydride solution is added dropwise to the suspension, causing Fe... 2+ In-situ reduction to generate nano-zero valent iron, which is then loaded onto the surface of NiCo-LDH nanosheets; S7. After the reaction is complete, the solid product is collected by centrifugation and washed with ultrapure water; then it is frozen and freeze-dried to obtain a nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material.
3. The nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material according to claim 2, characterized in that: In step S1, the water-soluble polymeric dispersant is carboxymethyl cellulose, sodium carboxymethyl cellulose, or sodium alginate.
4. The nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material according to claim 2, characterized in that: In step S2, the nickel salt is nickel acetate, nickel nitrate, nickel chloride, or nickel sulfate; the cobalt salt is cobalt acetate, cobalt nitrate, cobalt chloride, or cobalt sulfate.
5. The nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material according to claim 3, characterized in that: In step S2, the molar ratio of the nickel salt to the cobalt salt is 1:0.5 to 1:
2.
6. The nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material according to claim 2, characterized in that: In steps S5 and S6, the inert gas is nitrogen or argon.
7. The nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material according to claim 2, characterized in that: In step S5, the ferrous salt is ferrous sulfate, ferrous chloride, or ferrous nitrate.
8. The nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material according to claim 6, characterized in that: In step S5, the concentration of the ferrous salt solution is 0.02–0.06 M.
9. The nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material according to claim 2, characterized in that: In step S6, the concentration of the sodium borohydride solution is 0.01–0.2 mol / L.
10. Using the nano-zero-valent iron-supported nickel-cobalt layered double hydroxide composite material according to any one of claims 1-8 to remove U(VI) and TC pollutants from water.