A method for removing hexavalent chromium from water based on light-driven self-diffusion composite materials

Abstract

The present invention discloses a method for removing hexavalent chromium in water based on a light-driven self-diffusion composite material. The self-diffusion composite material is composed of graphene oxide and cuprous oxide with excellent photothermal efficiency. It not only demonstrates light-driven autonomous diffusion capabilities that are different from traditional environmental remediation functional materials, but also exhibits good removal efficiency for hexavalent chromium in water due to the disproportionation reaction of cuprous oxide under acidic conditions. Therefore, the light-driven self-diffusion composite material disclosed in the present invention effectively solves the diffusion requirements of environmental remediation functional materials that require external operations (such as magnetic force or mechanical stirring, etc.); at the same time, the controllable removal of hexavalent chromium pollution in water can be achieved by simply adjusting the pH of the contaminated water.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental remediation functional materials, and in particular relates to a method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material. Background Art

[0002] The development of functional materials for environmental remediation plays a vital role in sustainable environmental development. Heavy metal ion pollution is widely present in industrial and industrial wastewater, significantly impacting economic and social security. Among the various heavy metal ion contaminants, hexavalent chromium ions are highly mobile and difficult to degrade by aquatic organisms in the water environment. They can accumulate through biomass and enter the human body through the food chain, causing chronic poisoning and posing a serious threat to human health. Skin contact can cause allergies, inhalation can cause hereditary genetic defects, and drinking contaminated water carries a risk of cancer. It has been classified as a Class 1 carcinogen by the International Agency for Research on Cancer. Therefore, the development of low-cost, highly efficient functional materials for environmental remediation of hexavalent chromium contamination in water is urgent.

[0003] During use, traditional environmental remediation functional materials, especially heterogeneous remediation materials, have poor diffusion effects, resulting in insufficient contact with pollutants and the inability to fully exert their effectiveness. Therefore, in order to improve the contact between environmental remediation materials and pollutants and improve the low utilization rate caused by poor diffusion, it is often necessary to add external physical operations such as magnetic stirring or mechanical stirring during the environmental remediation process. In addition, commonly used methods for removing hexavalent chromium pollution include adsorption, chemical reduction, sedimentation, and photocatalytic reduction. For example, Chinese patent CN111717981A discloses a method for rapidly reducing hexavalent chromium ions using sodium borohydride (NaBH4) enhanced with oxalic acid. The catalytic effect of oxalic acid on the hydrolysis of NaBH4 improves the removal efficiency of hexavalent chromium by NaBH4. Chinese patent CN104876318A discloses a water treatment method for removing hexavalent chromium by reducing manganese dioxide / oxalic acid. Manganese oxide is used as a reducing agent, and oxalic acid provides electrons in the reaction process to reduce hexavalent chromium to trivalent chromium. Chinese patent CN107840429A discloses a method for preparing a metal organic polymer material for removing hexavalent chromium, the resulting materials, and applications. The reduction effect of iron-based organic polymer materials is used to repair hexavalent chromium pollution in water bodies.

[0004] The aforementioned methods for improving the diffusion of environmental remediation materials and technologies for removing hexavalent chromium pollution are generally costly, complex, and require demanding conditions, without controllable operation. Currently, there are no patents publicly available for utilizing the combined effects of light-driven self-diffusion and disproportionation reactions to achieve autonomous diffusion and controllable removal of hexavalent chromium pollution. Summary of the Invention

[0005] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0006] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: comprising:

[0009] The light-driven self-diffusion composite material is added to a hexavalent chromium solution, the solution pH is adjusted to 2-6, and the solution is irradiated with near-infrared light. The hexavalent chromium is reduced to low-toxic trivalent chromium through the disproportionation reaction of cuprous oxide under acidic conditions.

[0010] The light-driven self-diffusion composite material uses cuprous oxide as a carrier and has graphene oxide loaded on its surface.

[0011] As a preferred embodiment of the method for removing hexavalent chromium from water based on the light-driven self-diffusion composite material of the present invention, the light-driven self-diffusion capability is achieved by near-infrared light radiation, the wavelength of the near-infrared light is 800-1000 nm, and the power density is 0.5-5 W / cm 2 .

[0012] As a preferred solution of the method for removing hexavalent chromium from water based on light-driven self-diffusion composite materials of the present invention, the cuprous oxide is spherical with a particle size of 1 to 2 μm.

[0013] As a preferred embodiment of the method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to the present invention, the preparation method of the light-driven self-diffusion composite material includes dissolving a copper source, a photothermal agent, and sodium chloride in a mixed solution of water and ethanol, adding sodium hydroxide after mixing evenly, then adding a reducing agent, and finally reacting in a constant temperature water bath of 70 to 80°C to obtain the light-driven self-diffusion composite material.

[0014] As a preferred embodiment of the method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to the present invention, the copper source comprises one or more of copper acetate, copper chloride or copper sulfate.

[0015] As a preferred embodiment of the method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to the present invention, the photothermal agent is graphene oxide.

[0016] As a preferred embodiment of the method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to the present invention, the reducing agent comprises one or more of glucose, ascorbic acid or glutamic acid.

[0017] As a preferred embodiment of the method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to the present invention, the mass ratio of the copper source to the photothermal agent is 44.4 to 133.3:1, the mass ratio of the copper source to sodium chloride is 5 to 10:1, the concentration of the photothermal agent in the mixed solution is 0.09 to 0.625 mg / mL, and the volume ratio of water to ethanol in the mixed solution is 1:0.5 to 2.

[0018] As a preferred embodiment of the method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to the present invention, the concentration of the sodium hydroxide in the mixed solution is 12 to 28 mg / mL.

[0019] As a preferred embodiment of the method for removing hexavalent chromium from water based on light-driven self-diffusion composite materials of the present invention, the concentration of the reducing agent in the mixed solution is 10-20 mg / mL.

[0020] Beneficial effects of the present invention:

[0021] (1) The light-driven self-diffusion composite material prepared by the present invention exhibits light-driven autonomous diffusion capability that is different from traditional environmental remediation functional materials, effectively solving the diffusion requirements of traditional environmental remediation functional materials that require external operations (such as magnetic force or mechanical stirring, etc.) to achieve.

[0022] (2) Compared with other hexavalent chromium treatment methods, the light-driven self-diffusion composite material prepared by the present invention utilizes the disproportionation reaction of cuprous oxide under acidic conditions, and can controllably remove hexavalent chromium pollution in water by simply adjusting the pH of the contaminated water.

[0023] (3) The process of the present invention is simple and stable, easy to operate, has good reproducibility, and can be used for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive efforts. Among them:

[0025] Figure 1 Schematic diagram of the self-diffusion movement and hexavalent chromium (Cr(VI)) removal of the light-driven self-diffusion composite material (GO / Cu2O) prepared in Example 1 of the present invention;

[0026] Figure 2 is a scanning electron microscope image of the light-driven self-diffusion composite material prepared in Example 1 of the present invention;

[0027] Figure 3 This is an infrared spectrum of the light-driven self-diffusion composite material prepared in Example 1 of the present invention;

[0028] Figure 4 This is a comparison of the photothermal curves of the light-driven self-diffusion composite material prepared in Example 1 of the present invention and pure cuprous oxide under near-infrared light;

[0029] Figure 5 The light-driven self-diffusion composite material prepared in Example 1 of the present invention is 2 Self-diffusion motion diagram under near-infrared light;

[0030] Figure 6 The light-driven self-diffusion composite material prepared in Example 1 of the present invention and pure cuprous oxide are 2 Comparison of diffusion coefficient (MSD) under near-infrared light;

[0031] Figure 7 The light-driven self-diffusion composite material prepared in Example 1 of the present invention and pure cuprous oxide are 2 Self-diffusion velocity diagram under near-infrared light;

[0032] Figure 8 The light-driven self-diffusion composite material prepared in Example 1 of the present invention and pure cuprous oxide are 2 Comparison of hexavalent chromium removal efficiency under near-infrared light. DETAILED DESCRIPTION

[0033] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0035] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0036] Unless otherwise specified, the raw materials used in the present invention are all commercially available.

[0037] The performance of the materials prepared in the embodiment of the present invention was tested as follows:

[0038] Photothermal performance test: 10 mg of the composite material synthesized by the method of the present invention was added into 20 mL of water and then heated at 2 W / cm 2 The solution was irradiated with near-infrared light, and the temperature rise of the material was recorded using a near-infrared thermal imager for 10 minutes.

[0039] Self-diffusion performance test: 10 mg of the composite material synthesized by the method of the present invention was added to 100 mL of water to prepare a solution with a concentration of 0.1 g / L. 10 μL of the solution was dropped onto a glass slide and a 2 W / cm 2 Irradiate with near-infrared light, observe its movement performance under a microscope, record the movement coordinates, and calculate the movement data.

[0040] The performance test of removing hexavalent chromium ions from wastewater was as follows: 10 mg of the composite material synthesized by the method of the present invention was added to 20 mL of an aqueous solution containing hexavalent chromium ions, the concentration of hexavalent chromium ions was 50 ppm, the pH was adjusted to 2, and a 2 W / cm 2 The reduction efficiency was detected by near-infrared light irradiation and absorbance test method.

[0041] Example 1

[0042] This embodiment provides a method for preparing a light-driven self-diffusion composite material, specifically:

[0043] 200 mg of copper acetate and 30 mg of sodium chloride were added to a mixture of 8 mL of water and 7.9 mL of ethanol. The mixture was stirred for 2 min until the solute was completely dissolved. Then, 200 μL of GO solution (containing 3 mg of GO) was added. The mixture was stirred and heated until the temperature reached 70 °C.

[0044] 0.4 g of sodium hydroxide and 0.25 g of glucose were slowly added, and the solution was placed in a constant temperature water bath at 70° C. for 30 min to obtain a brown-red light-driven self-diffusing composite material.

[0045] Figure 1This is a scanning electron microscope image of the light-driven self-diffusion composite material prepared in Example 1 of the present invention. It can be seen that graphene oxide is loaded on the surface of cuprous oxide, indicating that the light-driven self-diffusion composite material has been successfully prepared.

[0046] Figure 2 This is the infrared spectrum of the light-driven self-diffusion composite material prepared in Example 1 of the present invention. Characteristic peaks of graphene oxide and cuprous oxide can be clearly observed, indicating that the light-driven self-diffusion composite material was successfully prepared.

[0047] Figure 3 This is a comparison diagram of the photothermal curves of pure cuprous oxide of the light-driven self-diffusion composite material prepared in Example 1 of the present invention under near-infrared light. It can be seen that the temperature of the light-driven self-diffusion composite material rises rapidly under near-infrared light, indicating that the light-driven self-diffusion composite material has good photothermal performance.

[0048] Figure 4 The light-driven self-diffusion composite material prepared in Example 1 of the present invention is 2 From the self-diffusion motion diagram under near-infrared light, it can be seen that the movement distance of the light-driven self-diffusion composite material is constantly increasing, indicating that the light-driven self-diffusion composite material has good self-diffusion performance.

[0049] Figure 5 The light-driven self-diffusion composite material prepared in Example 1 of the present invention and pure cuprous oxide are 2 From the comparison of diffusion coefficient (MSD) under near-infrared light, it can be seen that the MSD of the light-driven self-diffusion composite material is much greater than that of pure cuprous oxide, indicating that the motion performance of the light-driven self-diffusion composite material is much greater than that of pure cuprous oxide.

[0050] Figure 6 The light-driven self-diffusion composite material prepared in Example 1 of the present invention and pure cuprous oxide are 2 From the self-diffusion movement velocity diagram under near-infrared light, it can be seen that the movement speed of the light-driven self-diffusion composite material reaches 18.6μm / s, which is much greater than the movement speed of pure cuprous oxide.

[0051] Figure 7 The light-driven self-diffusion composite material prepared in Example 1 of the present invention and pure cuprous oxide are 2 The comparison chart of the removal efficiency of hexavalent chromium under near-infrared light shows that the light-driven self-diffusion composite material can completely reduce 50ppm of hexavalent chromium in 15 minutes. The ability to remove hexavalent chromium is much higher than that of pure cuprous oxide, indicating that the light-driven self-diffusion composite material has excellent ability to reduce hexavalent chromium.

[0052] Figure 8This is a schematic diagram of the self-diffusion movement and hexavalent chromium (Cr(VI)) removal of the light-driven self-diffusion composite material prepared in Example 1 of the present invention. As can be seen from the figure, the light-driven self-diffusion composite material can self-diffusion under near-infrared light and use the disproportionation reaction of cuprous oxide to quickly reduce hexavalent chromium.

[0053] Example 2

[0054] The difference between this embodiment and embodiment 1 is that the amount of graphene oxide added is adjusted from 200 μL to 100 μL (containing 3 mg GO, that is, the mass ratio of copper acetate to graphene oxide is 133.3:1), and the rest of the preparation process is the same as that of embodiment 1 to obtain a light-driven self-diffusion composite material.

[0055] Example 3

[0056] The difference between this embodiment and embodiment 1 is that the amount of graphene oxide added is adjusted from 200 μL to 300 μL (containing 4.5 mg GO, that is, the mass ratio of copper acetate to graphene oxide is 44.4:1), and the rest of the preparation process is the same as that of embodiment 1 to obtain a light-driven self-diffusion composite material.

[0057] The performance of the materials prepared in the above embodiment was tested, and the comparison results with those in Example 1 are shown in Table 1.

[0058] Table 1

[0059] Self-diffusion rate (μm / s) <![CDATA[K obs (min -1 )]]> Example 1 18.6 0.317 Example 2 10.5 0.087 Example 3 4.1 0.046

[0060] Note: K obs =ln(C0 / C), C0, C, K obs are the initial concentration, the concentration at the current time, and the kinetic constant of the reaction, respectively.

[0061] As can be seen from Table 1, adjusting the amount of graphene oxide added has a significant effect on the performance of the composite material. This is because if the amount of graphene oxide added is too large, the morphology of the composite material will be destroyed and the diffusion performance will be lost. If the amount of graphene oxide added is too small, the photothermal performance of the composite material will be poor and the diffusion performance will be weakened. According to the results in Table 1, the best technical effect can be obtained when the amount of graphene oxide added in the present invention is 200 μL.

[0062] Example 4

[0063] The difference between this embodiment and embodiment 1 is that the amount of glucose added is adjusted from 0.25 g to 0.17 g (ie, the concentration of glucose in the mixed solution is 10 mg / mL), and the rest of the preparation process is the same as that of embodiment 1 to obtain a light-driven self-diffusion composite material.

[0064] Example 5

[0065] The difference between this embodiment and embodiment 1 is that the amount of glucose added is adjusted from 0.25 g to 0.32 g (ie, the concentration of glucose in the mixed solution is 20 mg / mL), and the rest of the preparation process is the same as that of embodiment 1 to obtain a light-driven self-diffusion composite material.

[0066] The performance of the materials prepared in the above embodiment was tested, and the comparison results with those in Example 1 are shown in Table 2.

[0067] Table 2

[0068] Self-diffusion rate (μm / s) <![CDATA[K obs (min -1 )]]> Example 1 18.6 0.317 Example 4 8.4 0.057 Example 5 3.2 0.024

[0069] As can be seen from Table 2, adjusting the amount of glucose added has a significant effect on the performance of the composite material. This is because too much glucose added will cause the morphology of cuprous oxide to become cubic, while too little glucose added will result in the inability to completely reduce copper acetate to cuprous oxide. According to the results in Table 2, the best technical effect can be achieved when the amount of glucose added in the present invention is 0.25g.

[0070] Example 6

[0071] The difference between this embodiment and embodiment 1 is that the amount of sodium hydroxide added is adjusted from 0.4 g to 0.45 g, and the rest of the preparation process is the same as that of embodiment 1 to obtain a light-driven self-diffusion composite material.

[0072] Example 7

[0073] The difference between this embodiment and embodiment 1 is that the amount of sodium hydroxide added is adjusted from 0.4 g to 0.2 g, and the rest of the preparation process is the same as that of embodiment 1 to obtain a light-driven self-diffusion composite material.

[0074] The performance of the materials prepared in the above embodiment was tested, and the comparison results with those in Example 1 are shown in Table 3.

[0075] Table 3

[0076] Self-diffusion rate (μm / s) <![CDATA[K obs (min -1 )]]> Example 1 18.6 0.317 Example 6 1.2 0.012 Example 7 1.4 0.015

[0077] As can be seen from Table 3, adjusting the amount of sodium hydroxide added has a significant effect on the properties of the composite material. This is because too much sodium hydroxide added will cause the cuprous oxide morphology to become octahedral, while too little sodium hydroxide added will cause the cuprous oxide size to be too small. According to the results in Table 3, the best technical effect can be achieved when the amount of sodium hydroxide added in the present invention is 0.4 g.

[0078] Comparative Example 1

[0079] Pure cuprous oxide.

[0080] Comparative Example 2

[0081] Pure graphene oxide.

[0082] Comparative Example 3

[0083] This comparative example provides a conventional method for preparing a material for removing hexavalent chromium pollution, specifically:

[0084] Take 10mL of acetone, add 160mg of potassium dichromate, stir evenly, then measure 640uL of 4-vinylpyridine and stir for 1h; after stirring evenly, add 242uL of 2-hydroxyethyl methacrylate and 375uL of ethylene glycol dimethacrylate in sequence, and stir until the solution is uniform; add 60mg of azobisisobutyronitrile to the beaker and stir until uniform; transfer the mixed solution to a centrifuge tube, seal it and treat it with N2 for 15min, react in an oil bath under N2 balloon protection, set the temperature to 65℃, and react for 2h. Wash and dry to obtain a conventional material for removing hexavalent chromium pollution.

[0085] The performance of the material obtained in the above comparative example was tested without physical stirring, and the comparison results with those of Example 1 are shown in Table 4.

[0086] Table 4

[0087] Self-diffusion rate (μm / s) <![CDATA[K obs (min -1 )]]> Example 1 18.6 0.317 Comparative Example 1 0.8 0.007 Comparative Example 2 1.1 0.012 Comparative Example 3 0.7 0.009

[0088] As can be seen from the above table, the light-driven self-diffusion composite material disclosed in the present invention has unique light-driven self-diffusion properties compared to conventional hexavalent chromium removal materials. Under near-infrared light, the diffusion rate can reach 18.6 μm / s and hexavalent chromium can be quickly reduced, with 50 ppm of hexavalent chromium being completely reduced in 15 minutes.

[0089] In summary, the present invention discloses a method for removing hexavalent chromium in water based on a light-driven self-diffusion composite material. The self-diffusion composite material is composed of graphene oxide and cuprous oxide with excellent photothermal efficiency. It not only demonstrates light-driven autonomous diffusion capabilities that are different from traditional environmental remediation functional materials, but also stems from the disproportionation reaction of cuprous oxide under acidic conditions, showing good removal efficiency for hexavalent chromium in water. Therefore, the light-driven self-diffusion composite material disclosed in the present invention effectively solves the diffusion requirements of environmental remediation functional materials that require external operations (such as magnetic force or mechanical stirring, etc.); at the same time, through simple pH modulation of contaminated water, the controllable removal of hexavalent chromium pollution in water can be completed.

[0090] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material, characterized by: include, The light-driven self-diffusion composite material is added to a hexavalent chromium solution, the solution pH is adjusted to 2-6, and the solution is irradiated with near-infrared light. The hexavalent chromium is reduced to low-toxic trivalent chromium through the disproportionation reaction of cuprous oxide under acidic conditions. The light-driven self-diffusion composite material uses cuprous oxide as a carrier and has graphene oxide loaded on its surface.

2. The method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to claim 1, characterized in that: The near-infrared light has a wavelength of 800-1000 nm and a power density of 0.5-5 W / cm 2 .

3. The method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to claim 1, characterized in that: The cuprous oxide is spherical and has a particle size of 1 to 2 μm.

4. The method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to claim 1, characterized in that: The preparation method of the light-driven self-diffusion composite material, The method comprises the steps of dissolving a copper source, a photothermal agent and sodium chloride in a mixed solution of water and ethanol, adding sodium hydroxide after mixing evenly, then adding a reducing agent, and finally reacting in a constant temperature water bath of 70 to 80° C. to obtain a light-driven self-diffusion composite material.

5. The method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to claim 4, characterized in that: The copper source includes one or more of copper acetate, copper chloride or copper sulfate.

6. The method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to claim 4, characterized in that: The photothermal agent is graphene oxide.

7. The method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to claim 4, characterized in that: The reducing agent includes one or more of glucose, ascorbic acid or glutamic acid.

8. The method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to claim 4, characterized in that: The mass ratio of the copper source to the photothermal agent is 44.4-133.3:1, the mass ratio of the copper source to sodium chloride is 5-10:1, the concentration of the photothermal agent in the mixed solution is 0.09-0.625 mg / mL, and the volume ratio of water to ethanol in the mixed solution is 1:0.5-2.

9. The method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to claim 4, characterized in that: The concentration of the sodium hydroxide in the mixed solution is 12-28 mg / mL.

10. The method for removing hexavalent chromium from water based on a light-driven self-diffusion composite material according to claim 4, characterized in that: The concentration of the reducing agent in the mixed solution is 10-20 mg / mL.

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