A method for preparing a prussian blue adsorbing material grown in situ on a metal substrate

Abstract

The application relates to a preparation method of in-situ growth of Prussian blue adsorption material on a metal substrate, and belongs to the technical field of adsorption material preparation. The method comprises the following steps: (1) metal substrate pretreatment: the metal substrate is soaked and ultrasonically treated in an alkene acid, the substrate surface is rinsed with water and alcohol respectively, and the substrate is soaked in an anion solution for standby; (2) electrodeposition of Prussian blue: an electrodeposition solution is configured, the metal substrate is taken as a working electrode to carry out electrodeposition in the solution, Prussian blue is in-situ grown, and the Prussian blue adsorption material of the metal substrate is obtained. The application has the advantages of simple operation, low cost, controllable growth of Prussian blue on the substrate surface, and the produced metal substrate adsorption material is convenient to recycle and reuse after desorption, so that secondary pollution caused by the unrecoverable adsorption material is avoided.

Description

Technical Field

[0001] This invention relates to a method for preparing Prussian blue adsorbent material grown in situ on a metal substrate, belonging to the field of adsorbent materials and chemical separation technology. Background Technology

[0002] As global industrialization accelerates, the damage to the ecological environment caused by industrial production is intensifying. If waste gas, wastewater, and solid waste are not properly disposed of and are discharged indiscriminately, they will cause permanent damage to the entire Earth's ecosystem. In particular, waste containing heavy metals generated in the chemical industry, such as lead (Pb), cadmium (Cd), chromium (Cr), and metalloid arsenic (As), which have strong migration capabilities, will remain, accumulate, and migrate in nature in various chemical forms, eventually becoming enriched in a specific geographical location or organism, causing toxic effects on humans. Nuclear wastewater contains large amounts of radioactive elements, such as Sr-90, Cs-137, I-129, and C-14, whose half-lives are typically decades or even centuries long, and will eventually enter the human body through various means, causing cell carcinogenesis.

[0003] Heavy metals and radioactive elements are typically treated using methods such as chemical precipitation, adsorption, biological methods, and membrane separation. Adsorption has become a more reliable chemical separation method due to its advantages of simple operation, high efficiency, long-lasting effect, and wide adaptability. Furthermore, the diversity of adsorption materials brings more possibilities to adsorption methods. Currently, research has found that Prussian blue, while maintaining its climbing frame structure, can adsorb metal ions through ion substitution, and its adsorption capacity is higher than that of traditional adsorbents. Prussian blue and its analogues are inorganic adsorbents with an octahedral coordinated face-centered cubic structure and an internal cavity structure. Its unit cell parameters are a=b=c=10.134 Å, and the diameter of the central channel is 3.4 Å. Iron atoms are connected to cyanide ions on each edge and face. Fe(II) is connected to C in -CN-, while high-spin Fe(III) is connected to N in -CN-, with bond lengths of 1.92 Å and 2.03 Å, respectively. The face-centered cubic structure has four large cavities in the center, allowing ions of Group 1 (IA) elements to enter and occupy them. Therefore, ions with similar hydration radii can be selectively adsorbed by Prussian blue, and the Prussian blue family has a series of analogs based on differences in constituent elements, making it a promising candidate in the field of adsorption materials.

[0004] Patent CN117299097A discloses a method for preparing a Prussian blue composite adsorbent for selectively extracting cesium. The adsorbent involves first preparing polymer microspheres encapsulating ferric ions, then mixing them with a potassium ferrocyanide solution to obtain the Prussian blue composite adsorbent for selectively extracting cesium. This adsorbent has high loading capacity, high adsorption capacity, and is not easily lost, making it applicable to the extraction of cesium from salt lake brine, old brine, lithium precipitation mother liquor, seawater, and groundwater resources. However, the microsphere carrier is difficult to separate from the solution after adsorption, and a single Prussian blue adsorbent material is difficult to efficiently and selectively adsorb other elements. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for preparing Prussian blue adsorbent materials grown in situ on a metal substrate. (1) Metal substrate pretreatment: The metal substrate is immersed in olefinic acid and sonicated. After removal, the substrate surface is rinsed with water and alcohol respectively, and then immersed in an anionic solution for later use; (2) Electrodeposition of Prussian blue: An electrodeposition solution is prepared, and the metal substrate is used as the working electrode to perform in-situ electrodeposition of Prussian blue in the solution to obtain Prussian blue adsorbent materials on a metal substrate. The technical route provided by this invention is simple, and the conditions are mild and controllable. Prussian blue adsorbent materials with different metal ligands and nanoparticle sizes can be obtained by controlling the experimental conditions. The obtained adsorbent materials can be used for the adsorption research of heavy metal elements or radioactive elements, which can achieve efficient adsorption. Moreover, the presence of the metal substrate after adsorption makes the subsequent separation and desorption process more simplified. The specific steps are as follows: (1) Pretreatment of metal substrate: The metal substrate is immersed in olefinic acid and sonicated. After rinsing the substrate surface with water and alcohol respectively, it is immersed in anionic solution for later use. (2) Electrodeposition of Prussian blue: Prepare an electrodeposition solution, use a metal substrate as the working electrode to perform in-situ growth of Prussian blue by electrodeposition in the solution, and obtain a Prussian blue adsorbent material on a metal substrate.

[0006] Preferably, the metal substrate in step (1) is one of foamed iron, foamed cobalt, foamed nickel or foamed copper, with a pore size of 5~130 ppi.

[0007] Preferably, the alkanoic acid mentioned in step (1) is one or more of hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid, with a concentration of 10-50% and a soaking time of 10-60 min.

[0008] Preferably, the anionic solution in step (1) is one or more of K3[Fe(CN)6], K4[Fe(CN)6], K3[Co(CN)6] or K2[Ni(CN)4], with a concentration of 1~100 mM.

[0009] Preferably, the electrodeposition solution in step (2) is a mixed solution of an ionic solution containing a capping agent and an acid solution. The amount of capping agent is 1~10 g / L, the concentration of the ionic solution is 1~100 mM, and the concentration of the acid solution is 0.1 M. The capping agent is one or more of polyvinylpyrrolidone, polyvinyl alcohol, sodium dodecyl sulfate, hexadecyl dimethyl ammonium bromide, and octadecyl trimethyl ammonium chloride. The ionic solution donor is a mixed solution of KCl and one or more of K3[Fe(CN)6], K4[Fe(CN)6], K3[Co(CN)6] or K2[Ni(CN)4]. The acid solution is any one of hydrochloric acid, sulfuric acid, and nitric acid.

[0010] Preferably, the electrodeposition step in step (2) is performed using an electrochemical workstation, with a silver / silver chloride electrode as the reference electrode and a platinum electrode as the counter electrode, and the electrodeposition program is cyclic voltammetry.

[0011] Preferably, the electrodeposition potential range in step (2) is -1.2 to 1.2 V, and the number of cyclic scans is 1 to 100.

[0012] Compared with the prior art, the advantages and positive effects of the present invention are as follows: This invention uses foamed metal as the carrier of the adsorbent material, which has the advantages of low density and high strength, and also possesses a certain degree of toughness. During operation, it can effectively reduce the impact of equipment vibration, lower noise, and protect the equipment. In addition, foamed metal has a high porosity, allowing it to load more adsorbent material, enhancing the adsorption effect, and maintaining good integrity after adsorption. The substrate can be directly removed without causing secondary pollution due to the separation of adsorbent material.

[0013] By potentiating the foam substrate, corresponding metal ions are generated on its surface. Anions are deposited and Prussian blue or its analogues are grown in situ on the substrate surface, resulting in a tighter and more stable connection between the carrier and the adsorbent material, preventing delamination of the adsorbent material during adsorption vibration. Furthermore, Prussian blue can immobilize heavy metals or radioactive elements through various physical or chemical adsorption mechanisms, achieving higher adsorption capacities. Based on the differences in the diameter of the central channels of different analogues, selective adsorption of specific elements can be achieved. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the Cu@CuFe / CuCo-PBA adsorbent material prepared by electrodeposition in Example 1.

[0015] Figure 2 ab is the SEM image of Fe@FeFe / FeCo-PBA in Example 2, and cd is the SEM image of Ni@NiCo-PBA in Example 5.

[0016] Figure 3 The image shows the scanning curves for cyclic voltammetry electrodeposition in Example 5.

[0017] Figure 4 The data on the adsorption of cesium ions by the Co@CoCo-PBA adsorbent material prepared by electrodeposition in Example 6 at different pH values ​​are presented.

[0018] Figure 5 The curve showing the change in the amount of cesium ions adsorbed by the Cu@CuCo-PBA adsorbent material prepared by electrodeposition in Example 7 over time.

[0019] Figure 6 The adsorption rates of cesium ions in each embodiment and comparative example are shown.

[0020] Figure 7 This is an adsorption stability test for Example 1 and Comparative Example 2.

[0021] Figure 8 The graphs show the adsorption effects of lead, copper, and mercury ions on Examples 1, 5, and 9.

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments. Detailed Implementation

[0023] The technical solution of the present invention will be described in detail below.

[0024] Example 1. Preparation of Cu@CuFe / CuCo-PBA 1) Cut a piece of copper foam with a pore size of 10 ppi (area 1×2 cm). 2 The copper foam substrate was immersed in 40% dilute hydrochloric acid and sonicated for 10 min. After rinsing, it was rinsed with ethanol and water respectively, and then immersed in 10 mM K3[Fe(CN)6].

[0025] 2) Prepare an electrodeposition solution containing 2 g / L polyvinyl alcohol, 50 mM KCl, 10 mM K3[Fe(CN)6], 5 mM K3[Co(CN)6], and 0.1 M hydrochloric acid. Use the foamed copper substrate treated in step 1) as the working electrode, and immerse it in the electrodeposition solution along with a silver / silver chloride reference electrode and a platinum electrode. Select the cyclic voltammetry program on an electrochemical workstation and perform electrodeposition 30 times in the potential range of -1.2 to 1.2 V. After deposition, rinse with water and ethanol respectively, and vacuum dry in a vacuum drying oven at 60 °C for 2 h to obtain Cu@CuFe / CuCo-PBA.

[0026] like Figure 1The diagram shown illustrates the electrodeposition preparation of Cu@CuFe / CuCo-PBA adsorbent material in Example 1. Under electro-oxidation, the surface of the copper foam is preferentially oxidized, producing Cu. 2+ Simultaneously, [Fe(CN)6] in the electrodeposition solution 3- With [Co(CN)6] 3- Deposited onto the surface of copper foam with Cu 2+ Upon contact, the reaction generates Cu3[Fe(CN)6]2 (CuFe-PBA) and Cu3[Co(CN)6]2 (Cu@CuFe / CuCo-PBA), enabling the in-situ growth of adsorbent materials on the surface of the metal substrate, eliminating material gaps, and resulting in a stronger bond.

[0027] Example 2. Preparation of Fe@FeFe / FeCo-PBA This embodiment is the same as Embodiment 1, except that in this embodiment, foamed iron is selected as the metal substrate for electrodeposition to obtain Fe@FeFe / FeCo-PBA.

[0028] like Figure 2 (ab) shows the SEM image of Fe@FeFe / FeCo-PBA adsorbent material prepared by electrodeposition in Example 2. The adsorbent material is controlled by the capping agent to form petal-shaped two-dimensional nanosheets on the surface of foamed iron, with a thin layered structure and a large horizontal size.

[0029] Example 3. Preparation of Co@CoFe / CoCo-PBA This embodiment is the same as Embodiment 1, except that in this embodiment, cobalt foam is selected as the metal substrate for electrodeposition to obtain Co@CoFe / CoCo-PBA.

[0030] Example 4. Preparation of Ni@NiFeNiCo-PBA This embodiment is the same as Embodiment 1, except that in this embodiment, nickel foam is selected as the metal substrate for electrodeposition to obtain Ni@NiFeNiCo-PBA.

[0031] Example 5. Preparation of Ni@NiCo-PBA 1) Cut a piece of nickel foam with a pore size of 50 ppi (area 1×2 cm). 2 The nickel foam substrate was immersed in 10% dilute nitric acid and sonicated for 10 min. After rinsing, it was rinsed with ethanol and water respectively, and then immersed in 5 mM K3[Co(CN)6].

[0032] 2) Prepare an electrodeposition solution containing 10 g / L polyvinylpyrrolidone, 60 mM KCl, 20 mM K3[Co(CN)6], and 0.1 M sulfuric acid. Use the nickel foam substrate treated in step 1) as the working electrode, and immerse it in the electrodeposition solution along with a silver / silver chloride reference electrode and a platinum electrode. Select the cyclic voltammetry program on an electrochemical workstation and perform 60 electrodepositions within the potential range of 0–1.2 V. After deposition, rinse with water and ethanol respectively, and vacuum dry at 60 °C for 2 h to obtain Ni@NiCo-PBA. Figure 2 (cd) is a SEM image of the Ni@NiCo-PBA adsorbent material prepared by electrodeposition in Example 5. The adsorbent material is controlled by the capping agent to form continuously growing nanocubes on the surface of nickel foam. The three-dimensional cubic structure provides a larger specific surface area.

[0033] like Figure 3 The image shows the cyclic voltammetry electrodeposition scan curves for Example 5, specifically the 10th, 20th, and 30th cyclic voltammetry curves. The curves exhibit [Co(CN)6] at 0.8V and 0.7V. 3- The redox peaks are observed, and NiCo-PBA grows in situ on the surface of nickel foam through multiple redox reactions.

[0034] Example 6. Preparation of Co@CoCo-PBA This embodiment is the same as embodiment 5, except that in this embodiment, cobalt foam is selected as the metal substrate for electrodeposition to obtain Co@CoCo-PBA.

[0035] Example 7. Preparation of Cu@CuCo-PBA This embodiment is the same as Embodiment 5, except that copper foam is selected as the metal substrate for electrodeposition to obtain Cu@CuCo-PBA.

[0036] Example 8. Preparation of Fe@FeCo-PBA This embodiment is the same as Embodiment 5, except that in this embodiment, foamed iron is selected as the metal substrate for electrodeposition to obtain Fe@FeCo-PBA.

[0037] Example 9. Preparation of Fe@FeNi-PBA 1) Cut a piece of foam iron with a pore size of 100 ppi (area 1×2 cm) 2 The foamed iron substrate was immersed in 20% dilute sulfuric acid and sonicated for 10 min. After rinsing, it was rinsed with ethanol and water respectively, and then immersed in 30 mM K2[Ni(CN)4].

[0038] 2) Prepare an electrodeposition solution containing 5 g / L sodium dodecyl sulfate, 10 mM KCl, 50 mM K2[Ni(CN)4], and 0.1 M nitric acid. Use the nickel foam substrate treated in step 1) as the working electrode, and immerse it in the electrodeposition solution along with a silver / silver chloride reference electrode and a platinum electrode. Select the cyclic voltammetry program on an electrochemical workstation and perform 90 electrodepositions within the potential range of -1.2 to 1.2 V. After deposition, rinse with water and ethanol respectively, and vacuum dry in a vacuum drying oven at 60 °C for 2 h to obtain Fe@FeNi-PBA.

[0039] Comparative Example 1 Comparative Example 1 is the same as Example 1, except that the electrodeposition potential range of Comparative Example 1 is selected as -1.2~0 V.

[0040] Comparative Example 2 Comparative Example 2 is the same as Example 1, except that the copper foam in Comparative Example 1 is not soaked in anionic solution after treatment.

[0041] The application of Prussian blue adsorbent materials grown in situ on metal substrates is illustrated using specific examples and comparative examples.

[0042] The adsorbent material prepared in Specific Example 6 was applied to determine its removal efficiency for the heavy metal cesium under different pH conditions. The application method was as follows: Add 100 mL of 10 g / L cesium chloride solution to each conical flask, and adjust the pH to a range of 3-8 (specifically 3, 4, 5, 6, 7, and 8). Add the Co@CoCo-PBA prepared in Example 6 to each conical flask, and allow the mixture to react in a shaker at room temperature for 1 h. Measure the cesium ion concentration before and after the reaction using flame atomic absorption spectrometry, and calculate the adsorption capacity of Co@CoCo-PBA in Example 6 under different pH conditions. Figure 4 As shown, Co@CoCo-PBA exhibits a large adsorption capacity over a wide pH range, with the highest adsorption capacity of 735.8 mg at pH=6.

[0043] The phosphogypsum adsorbent prepared in Specific Example 7 was applied, and the change in adsorption capacity of the adsorbent over time was measured. The application method was as follows: Add 100 mL of 10 g / L cesium chloride solution to an Erlenmeyer flask, adjust the pH to 6, and then add the Cu@CuCo-PBA prepared in Example 7. React with shaking at room temperature for 0-1 h (specifically 0 min, 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min). Samples were taken at different time points, and the cesium ion content in the solution was determined using flame atomic absorption spectrometry to obtain the change in adsorption capacity of the adsorbent over time. Figure 5 As shown, Cu@CuCo-PBA has the highest efficiency at 30 min, with an adsorption capacity of 701.3 mg at this time.

[0044] The Prussian blue adsorbent material prepared in situ on a metal substrate using specific embodiments and comparative examples was applied to investigate the adsorption rate of cesium on different metal substrates and with different metal ligands. The application method is as follows: Add 100 mL of 10 g / L cesium chloride solution to an Erlenmeyer flask, adjust the pH to 6, and add the Prussian blue adsorbent material prepared in situ on the metal substrate in the specific examples and comparative examples, respectively. Shake the reaction at room temperature for 30 min to allow for complete adsorption. Detect the cesium content of each example after the reaction and calculate the adsorption rate. Figure 6 As shown, the adsorption rate of cesium by the adsorbent materials is generally above 70%, with Fe@FeFe / FeCo-PBA showing the highest adsorption rate at 98.5%, while Fe@FeNi-PBA shows 75.6%. The main reason for the difference is that the hydration radius of the cavities in the different analogs is different. The hydration radius of cesium ions is similar to that of FeFe and FeCo-PBA, thus resulting in a better adsorption effect. The analogs may have a better adsorption effect on other ions. The adsorption rate of Comparative Example 1 is only 67.2%, indicating that only physical adsorption occurs.

[0045] The Prussian blue adsorbent materials prepared in Example 1 and Comparative Example 2 were used to grow in situ on metal substrates, and their adsorption stability under repeated use was investigated. The application method was as follows: Add 100 mL of 10 g / L cesium chloride solution to an Erlenmeyer flask, adjust the pH to 6, and add the Prussian blue adsorbent materials grown in situ on the metal substrates prepared in Example 1 and Comparative Example 2, respectively. Shake the reaction at room temperature for 30 min to allow for complete adsorption. Calculate the adsorption rates of both. Regenerate the adsorbent materials by immersing them in potassium ion solution for 1 h. Repeat the regeneration process 10 times. Figure 7 The figure shows the stability test of repeated adsorption of Example 1 and Comparative Example 2. After repeated use, the Prussian blue adsorbent material prepared in Example 1 still maintains a high adsorption value. The stability is due to the formation of seed crystals on the metal substrate, which makes the growth of Prussian blue more stable and uniform in the subsequent electrodeposition process.

[0046] The Prussian blue adsorbent materials prepared in Examples 1, 5, and 9 were used to grow in situ on metal substrates to investigate their adsorption effects on different metal ions. The application method was as follows: Solutions containing lead, copper, and cadmium ions of equal concentration were prepared, and Prussian blue adsorbent materials prepared in situ on metal substrates according to Examples 1, 5, and 9 were added respectively. Adsorption was completed under optimal conditions, and the adsorption rate was calculated. Figure 8 As shown, Examples 1 and 5 showed good adsorption effects on lead and mercury ions, but poor adsorption effects on copper ions. However, Example 9 showed the opposite results. This is because the hydration radius of lead ions is 1.75 Å, the hydration radius of mercury ions is 1.02 Å, and the hydration radius of copper ions is 4.0 Å. Therefore, Prussian blue materials with larger central channel radii are needed to adsorb these metal ions.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. The application of a Prussian blue adsorbent material grown in situ on a metal substrate for the adsorption of cesium ions, characterized in that, The preparation steps of the adsorbent material are as follows: (1) Pretreatment of metal substrate: The metal substrate is immersed in dilute acid and sonicated. After rinsing the substrate surface with water and alcohol respectively, it is immersed in an anionic solution for later use. The anionic solution is K3[Fe(CN)6] solution with a concentration of 1~100 mM. The dilute acid is one or more of hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid with a concentration of 10~50%. The metal substrate is foamed iron. (2) Electrodeposition of Prussian blue: Prepare an electrodeposition solution, use a metal substrate as the working electrode to perform in-situ electrodeposition of Prussian blue in the solution, and obtain the adsorbent material; The electrodeposition solution is a mixed solution of an ionic solution containing a capping agent and an acid solution. The amount of capping agent is 1~10 g / L, the concentration of the ionic solution is in the range of 1~100 mM, and the concentration of the acid solution is 0.1 M. The capping agent is polyvinyl alcohol, and the ion solution donor is a mixed solution of KCl, K3[Fe(CN)6] and K3[Co(CN)6]; the acid solution is any one of hydrochloric acid, sulfuric acid and nitric acid; the electrodeposition potential range is -1.2~1.2 V, the number of cyclic scans is 1~100, and the electrodeposition program is cyclic voltammetry.

2. The application according to claim 1, characterized in that, The pore size of the metal substrate is 5~130 ppi.

3. The application according to claim 1, characterized in that, The soaking time in dilute acid in step (1) is 10~60 min.

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