Phytic acid loaded porous carbon material as well as preparation method and application thereof

Abstract

The invention discloses a phytic acid loaded porous carbon material as well as a preparation method and application thereof. The preparation method of the phytic acid loaded porous carbon material comprises the following steps: acidifying a carbon material, heating, centrifuging, washing and drying to obtain a modified carbon material; mixing and stirring the modified carbon material and titanate, adding a phytic acid solution, heating and stirring to obtain a phytic acid modified carbon mixed solution; heating and fixing the phytic acid modified carbon mixed solution into xerogel, dissolving the xerogel into deionized water, centrifuging, washing and drying to obtain the phytic acid loaded porous carbon material. When the phytic acid loaded porous carbon material is used in a flow electrode, the problem that a traditional electrode material is easy to block is effectively avoided, the adsorption rate and the adsorption capacity of uranyl ions are remarkably improved, and the adsorption capacity of the uranyl ions can reach 500 mg / g or above. Compared with a traditional porous carbon material, the phytic acid loaded porous carbon material has higher capacitive adsorption performance and better uranium removal efficiency, and can be widely applied to deep purification treatment of uranium-containing wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental functional materials, and specifically relates to a phytic acid-loaded porous carbon material and a preparation method and application thereof. Background Art

[0002] Uranium, as a radioactive heavy metal element, is widely distributed in nature and is released into the environment during the nuclear industry, uranium mining and nuclear waste treatment, causing serious water pollution. Uranium-containing wastewater is highly toxic and persistent, posing a major threat to the ecological environment and human health.

[0003] In recent years, electrosorption technology has shown wide application potential in the field of water treatment due to its advantages such as simple operation, no chemical additives, and low energy consumption. This technology adsorbs metal ions in water through electrode materials and has efficient ion separation capabilities. However, the quality of electrosorption performance depends to a large extent on the properties of the electrode materials, especially the conductivity, surface functional groups and specific surface area of ​​the materials. As an important electrode material in electrosorption technology, carbon-based materials have become the mainstream choice in this field due to their excellent conductivity, chemical stability and large specific surface area.

[0004] At present, a variety of carbon-based materials have been studied for the adsorption of uranyl ions. For example, CN117101613A discloses a collagen fiber-based nanofiber sulfide, which can achieve a maximum adsorption of uranyl ions of 300-400 mg / g, but its adsorption capacity still needs to be further improved to meet the needs of larger-scale uranium wastewater treatment. CN111410274B discloses a titanium-based material incorporated into a flow electrode. Although this material can increase the adsorption rate of uranyl ions, it still fails to solve the problem of easy agglomeration and deposition of carbon-based materials in water, which may cause pipeline blockage and decreased efficiency of the flow electrode. Therefore, when treating uranium-containing wastewater, the existing carbon-based materials still have problems such as low adsorption capacity, poor hydrophilicity and easy clogging of pipelines.

[0005] As a natural organic polyphosphate compound, phytic acid has strong metal ion complexing ability and high selectivity, and is therefore widely studied for the adsorption of heavy metal ions. Phytic acid is loaded onto the surface of carbon-based materials, which can not only significantly increase the surface binding sites of carbon materials, but also improve the adsorption capacity of uranyl ions, and its abundant phosphate groups can improve the hydrophilicity of carbon materials, improve their dispersibility and anti-sedimentation ability in aqueous phase systems. However, the phytic acid hollow microspheres disclosed in prior art such as CN118872670A still have certain deficiencies in phytic acid loading, material stability and application effect, and are difficult to meet the actual needs of electrosorption treatment of uranium-containing wastewater. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. The present invention proposes a phytic acid-loaded porous carbon material and a preparation method thereof and its application in treating uranium-containing wastewater by flow electrode electrosorption. The phytic acid-loaded porous carbon flow electrode prepared by phytic acid loading significantly improves the adsorption performance of the electrosorption material, improves the hydrophilicity of the carbon-based material, and improves the removal efficiency of uranyl ions during the electrosorption process.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A first aspect of the present invention provides a method for preparing a phytic acid-loaded porous carbon material.

[0009] The method for preparing the phytic acid-loaded porous carbon material provided by the present invention comprises the following steps:

[0010] 1) Acidifying, heating, centrifuging, washing and drying the carbon material to obtain a modified carbon material;

[0011] 2) mixing the modified carbon material with the titanate solution and stirring, and then adding the phytic acid solution and heating and stirring to obtain a phytic acid modified carbon mixed solution;

[0012] 3) The phytic acid-modified carbon mixed solution is heated and fixed into a dry gel, dissolved in deionized water, centrifuged, washed, and dried to obtain a phytic acid-loaded porous carbon material.

[0013] In step 1) of the above method, the carbon material is at least one of activated carbon, carbon fiber, carbon nanotube and biochar;

[0014] The acid used for the acidification is at least one of nitric acid, sulfuric acid, hypochlorous acid and perchloric acid, and the concentration of the acid can be 3 to 15 mol / L;

[0015] The solid-liquid ratio of the carbon material to the acid may be 1 g: (10-50) mL;

[0016] The heating treatment is at least one of water bath heating and oil bath heating, the heating temperature can be 50° C. to 80° C., and the heating time can be 1 h to 8 h;

[0017] The detergent used for washing is at least one of deionized water, ethanol and diluted alkaline solution;

[0018] The diluted alkali solution is at least one of potassium carbonate, sodium carbonate, potassium hydroxide and sodium hydroxide solution, and the concentration of the diluted alkali solution may be 0.01 to 0.5 mol / L.

[0019] In step 2) of the above method, the titanate is tetrabutyl titanate and / or isopropyl titanate;

[0020] The concentration of the titanate solution may be 0.01 to 0.1 mol / L, and the solid-liquid ratio of the modified carbon material to the titanate solution may be 1 g: (10 to 30) mL.

[0021] In step 2) of the above method, the mixing and stirring time can be 1 hour to 6 hours.

[0022] The concentration of the phytic acid solution may be 0.1-1 mol / L, and the solid-liquid ratio of the modified carbon material to the phytic acid solution may be 1 g:(10-50) mL.

[0023] In step 2) of the above method, the heating temperature of the heating and stirring can be 50° C. to 90° C., and the time can be 1 hour to 12 hours.

[0024] In step 3) of the above method, the heating temperature of the fixed heating can be 120° C. to 200° C., and the time can be 6 h to 24 h.

[0025] The washing is to wash the dissolved dry gel with deionized water until the washing liquid is weakly acidic; the pH value of the weakly acidic water is 5.5-6.5.

[0026] The drying temperature may be 50°C to 100°C.

[0027] The second aspect of the present invention provides a phytic acid-loaded porous carbon material, wherein the phytic acid-loaded porous carbon material is prepared by the above-mentioned method for preparing the phytic acid-loaded porous carbon material.

[0028] The third aspect of the present invention provides the use of the above-mentioned phytic acid-loaded porous carbon material in the treatment of uranium-containing wastewater by mobile electrode electrosorption.

[0029] According to a fourth aspect of the present invention, a flow electrode is provided.

[0030] The flow electrode comprises an electric adsorption material, and the electric adsorption material is the above-mentioned phytic acid-loaded porous carbon material.

[0031] According to some embodiments of the present invention, the concentration of the phytic acid-loaded porous carbon material in the flow electrode is 1-20 g / L.

[0032] A fifth aspect of the present invention provides a device for removing uranyl ions by electrosorption.

[0033] The device for removing uranyl ions by electric adsorption comprises the above-mentioned mobile electrode, uranium waste liquid to be treated, an anion exchange membrane and a cation exchange membrane.

[0034] The step of removing uranium from wastewater by using the electro-absorption uranyl ion removal device comprises: circulating the flow electrode formed by the phytic acid-loaded porous carbon material into the electro-absorption uranyl ion removal device, and removing uranium from the uranium waste liquid to be treated under power-on conditions.

[0035] In some embodiments, in the mobile electrode device for removing uranyl ions by electrosorption, the cathode and the anode circulate in the same container in SCC mode after adsorbing uranyl ions.

[0036] In some embodiments, the flow rate of the mobile electrode and the uranium waste liquid to be treated in the device for removing uranyl ions by electrosorption is in the range of 10 to 50 mL / min.

[0037] In some embodiments, the power-on mode is a constant voltage mode. Preferably, the constant voltage has a voltage range of 1.2 to 3.6V.

[0038] The beneficial effects of the present invention are as follows: the present invention provides a method for preparing a phytic acid-loaded porous carbon material, wherein a carbon material is acidified with a strong acid to obtain functional groups such as carboxyl and phenolic hydroxyl groups, and a phytic acid-loaded porous carbon material of nanometer size is obtained by the catalytic effect of a titanate and a heat fixation treatment. The hydrophilicity and electrical conductivity of phytic acid and the strong interaction with uranyl ions improve the hydrophilicity, electrical conductivity and the ability to capture uranyl ions of the porous carbon material after loading. In addition, by acidification with a strong acid, the porous carbon material can obtain a lattice structure with more site holes, which increases the adsorption sites of the porous carbon material for uranyl ions. The phytic acid material can be more stably loaded onto the porous carbon material by the catalytic effect of a titanate and a heat fixation. The use of the phytic acid-loaded porous carbon material in a flow electrode not only effectively avoids the problem of easy clogging of traditional electrode materials, but also significantly improves the adsorption rate and adsorption capacity of uranyl ions, thereby enhancing the working efficiency of the flow electrode. Compared with traditional porous carbon materials, the phytic acid-loaded porous carbon material has higher capacitive adsorption performance and better uranium removal effect, and can be widely used in the deep purification treatment of uranium-containing wastewater, solving the problems of low capacitive adsorption capacity and low uranium removal efficiency of traditional porous carbon materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a SEM image of the phytic acid-loaded porous carbon material prepared in Example 1 of the present invention.

[0040] Figure 2 These are the test results of the adsorption capacity of the porous carbon material and the phytic acid-loaded porous carbon material for uranyl ions in Example 2 of the present invention.

[0041] Figure 3 Schematic diagram of the device for removing uranyl ions by electrosorption in Example 2 of the present invention.

[0042] Figure 4 This is a diagram showing the effect of electrosorption of uranyl ions by phytic acid-loaded porous carbon material and pure porous carbon in Example 2 of the present invention. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0044] The experimental methods in the following examples, unless otherwise specified, are all conventional methods, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial channels.

[0045] Example 1

[0046] The embodiment of the present invention provides a phytic acid-loaded porous carbon material, which is prepared according to the following steps: placing the porous activated carbon material in a 6 mol / L nitric acid solution, heating and stirring in a 60°C water bath for 4 hours, centrifuging, washing with deionized water, and vacuum drying to obtain a modified carbon material. The solid-liquid ratio of the porous activated carbon material to the nitric acid solution is 1 g:20 mL.

[0047] The modified carbon material was mixed with 0.01 mol / L tetrabutyl titanate solution, stirred magnetically for 3 hours, and then 0.5 mol / L phytic acid solution was added and heated in a water bath at 80°C and stirred for 6 hours to obtain a phytic acid modified carbon mixed solution. The solid-liquid ratio of the modified carbon material to the tetrabutyl titanate solution and the phytic acid solution was 1 g:15 mL:30 mL.

[0048] The phytic acid-modified carbon mixture was heated in an oven at 180°C for 12 h to obtain a dry gel, which was then dissolved in deionized water. The mixture was centrifuged and washed with deionized water until the washing liquid was weakly acidic (pH 6), and then dried in a vacuum at 60°C to obtain a phytic acid-loaded porous carbon material (pH test paper showed that when the pH was 6, the excess phytic acid had been basically washed away).

[0049] The SEM image of the obtained phytic acid loaded porous carbon material is shown in Figure 1 shown.

[0050] Table 1 shows the contact angle measurement results of the porous carbon material and the phytic acid-loaded porous carbon material by the sessile drop method. It can be seen from the table that, compared with the porous carbon material (referring to the raw porous activated carbon material used in Example 1), the phytic acid-loaded porous carbon material prepared by the present invention, the contact angle of the sessile drop method is reduced from 96.9° to 43.8°, indicating that the hydrophilicity of the porous carbon material can be improved by loading with phytic acid, thereby effectively avoiding the problem of easy clogging of traditional porous carbon materials as flow electrodes.

[0051] Table 1 Contact angle measurement results of porous carbon materials and phytic acid loaded porous carbon materials by sessile drop method

[0052]

[0053]

[0054] Figure 2 The results of the test of the adsorption capacity of uranyl ions in the static adsorption of porous carbon materials and phytic acid loaded porous carbon materials are shown. It can be seen from the figure that compared with the porous carbon material, the phytic acid loaded porous carbon material prepared in the embodiment of the present invention has an adsorption capacity of uranyl ions increased from 78.2 mg / g to 507.7 mg / g, indicating that the adsorption capacity of porous carbon materials for uranyl ions can be increased by phytic acid loading, so that more uranium-containing wastewater can be adsorbed and treated, and the replacement frequency of adsorption materials can be reduced. The test data of the adsorption capacity of uranyl ions of the above-mentioned porous carbon materials and phytic acid loaded porous carbon materials are fitted by the Langmuir model, R 2 They are 0.975 and 0.997 respectively.

[0055] Example 2

[0056] This embodiment provides a mobile electrode to remove uranium from uranium-containing wastewater, and the steps are as follows:

[0057] The phytic acid loaded porous carbon material prepared in Example 1 was dissolved in deionized water and ultrasonically dispersed to prepare a flow electrode, wherein the concentration of the phytic acid loaded porous carbon material was 5 g / L.

[0058] See also Figure 3 The mobile electrode and uranium-containing wastewater are circulated into the electric adsorption uranium removal device and separated by the ion exchange membrane at a flow rate of 40 mL / min, and the uranium-containing wastewater is removed from the uranium in a power-on mode of a constant voltage of 1.2 V. The mobile electrode, cathode and anode in this embodiment are circulated in the same container in the SCC mode after adsorbing uranyl ions. The relevant parameters of the ion exchange membrane in this embodiment are shown in Table 2.

[0059] Table 2. Parameters of ion exchange membranes

[0060]

[0061] Comparative Example

[0062] The comparative example is the same as Example 2, except that only porous carbon (referring to the raw porous activated carbon material used in Example 1) is used as the electrosorption material to form a simple porous carbon flow electrode for uranium removal.

[0063] Figure 4The uranium removal effects of the flow electrode prepared by the present invention and the simple porous carbon flow electrode are shown. It can be seen from the figure that compared with the flow electrode made of porous carbon alone, the FCDI uranyl ion removal rate of the phytic acid-loaded porous carbon flow electrode prepared by the present invention is increased from 79% to 91%, indicating that the use of the phytic acid-loaded porous carbon flow electrode of the present invention in the flow electrode can increase the adsorption rate of the electrosorption material for uranyl ions, thereby accelerating the uranium removal process.

[0064] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, and without the need to carry out unnecessary experimental conditions, the present invention can be implemented in a wide range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that the present invention can be further improved. In a word, according to the principles of the present invention, the application is intended to include any changes, uses or improvements to the present invention, including departure from the disclosed scope in the application, and changes made with conventional techniques known in the art.

Claims

1. A method for preparing a phytic acid-loaded porous carbon material, comprising the following steps: 1) Acidifying, heating, centrifuging, washing and drying the carbon material to obtain a modified carbon material; 2) mixing the modified carbon material with the titanate solution and stirring, and then adding the phytic acid solution and heating and stirring to obtain a phytic acid modified carbon mixed solution; 3) The phytic acid-modified carbon mixed solution is heated and fixed into a dry gel, dissolved in deionized water, centrifuged, washed, and dried to obtain a phytic acid-loaded porous carbon material.

2. The method according to claim 1, characterized in that In step 1), the carbon material is at least one of activated carbon, carbon fiber, carbon nanotube and biochar; The acid used for the acidification is at least one of nitric acid, sulfuric acid, hypochlorous acid and perchloric acid, and the concentration of the acid is 3 to 15 mol / L; The solid-liquid ratio of the carbon material to the acid is 1 g: (10-50) mL; The heating treatment is at least one of water bath heating and oil bath heating, the heating temperature is 50° C. to 80° C., and the heating time is 1 h to 8 h.

3. The method according to claim 1, characterized in that: In step 2), the titanate is tetrabutyl titanate and / or isopropyl titanate; The concentration of the titanate solution is 0.01-0.1 mol / L, and the solid-liquid ratio of the modified carbon material to the titanate solution is 1 g: (10-30) mL; The mixing and stirring time is 1 h to 6 h.

4. The method according to claim 1, characterized in that: The concentration of the phytic acid solution is 0.1-1 mol / L, and the solid-liquid ratio of the modified carbon material to the phytic acid solution is 1 g: (10-50) mL; The heating temperature of the heating and stirring is 50° C. to 90° C., and the time is 1 h to 12 h.

5. The method according to claim 1, characterized in that: In step 3), the heating temperature is fixed at 120° C. to 200° C., and the heating time is 6 h to 24 h. The washing is to wash the dissolved dry gel with deionized water until the washing liquid is weakly acidic; the pH value of the weakly acidic water is 5.5-6.

5.

6. Phytic acid-loaded porous carbon material prepared by the method according to any one of claims 1 to 5.

7. Use of the phytic acid-loaded porous carbon material according to claim 6 in treating uranium-containing wastewater by mobile electrode electrosorption.

8. A flow electrode, comprising an electrosorption material, wherein the electrosorption material is the phytic acid-loaded porous carbon material according to claim 6.

9. An electrosorption device for removing uranyl ions, comprising the mobile electrode according to claim 8, uranium waste liquid to be treated, an anion exchange membrane and a cation exchange membrane.

10. A method for removing uranium from wastewater using the electrosorption uranyl ion removal device according to claim 9, comprising the steps of: circulating the mobile electrode formed by the phytic acid-loaded porous carbon material into the electrosorption uranyl ion removal device, and deuranizing the uranium waste liquid to be treated under power-on conditions.

Images