Tourmaline composite catalyst as well as preparation method and application thereof

Abstract

The invention provides a tourmaline composite catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalysts. The preparation method of the tourmaline composite catalyst comprises the following steps: adding tourmaline and tannic acid into an acid solution, and stirring for reaction to obtain a mixed solution; placing the mixed solution in a closed environment, and heating for reaction to obtain the tourmaline composite catalyst. According to the preparation method provided by the invention, tannic acid is successfully modified on tourmaline through a complex reaction and a hot solvent method, the tourmaline composite catalyst material is prepared, and the preparation method is simple in preparation process, simple and convenient to operate and low in cost. The tourmaline composite catalyst disclosed by the invention is used for carrying out advanced oxidation reaction on the insecticide wastewater, has the advantages of simple application method, low cost, high insecticide removal rate and the like, can realize effective degradation of insecticides in the wastewater, and has a relatively good application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly relates to a tourmaline composite catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, advanced oxidation processes have developed rapidly. In particular, the degradation technology of advanced oxidation processes based on transition metal materials for the removal of environmental pollutants has received extensive attention from researchers.

[0003] The advanced oxidation process mainly based on persulfate is mainly activated and reacted by means of transition metals, and the properties of transition metal catalysts determine whether they have good persulfate activation performance. Therefore, the design and preparation of efficient transition metal catalytic materials have become the focus of research in the field of persulfate advanced oxidation at present.

[0004] In the selection and application of catalyst materials, transition metal oxides (such as iron oxide, ferrite, etc.) represented by Fe have attracted extensive attention. However, in the advanced oxidation process, with the progress of the reaction, Fe species with poor reactivity are continuously generated, which will lead to a decline in the performance of the reaction system and the loss of the catalyst. Therefore, it is not environmentally friendly and economical to use transition metal oxides of Fe to directly activate persulfate to degrade pollutants.

[0005] Among natural minerals, tourmaline containing Fe is a good choice. The Fe in tourmaline has a relatively stable structure and can stably activate persulfate for a long time, and the weak electric field on the surface of tourmaline can also activate persulfate. However, limited by the chemical coordination state, the activity of Fe in tourmaline is relatively low, and the efficiency of tourmaline activating persulfate is still not ideal. Therefore, obtaining a tourmaline composite catalyst with high activity is of great significance for improving the effect of tourmaline activating persulfate to degrade pollutants. Summary of the Invention

[0006] In order to overcome the problem that the activation of persulfate by transition metal materials in the prior art is uneconomical and not environmentally friendly, the present invention provides a tourmaline composite catalyst, a preparation method thereof, and an application thereof. The preparation method provided by the present invention is simple and can be carried out at normal temperature and pressure. The obtained tourmaline composite catalyst has the advantages of high persulfate utilization rate, high removal rate of pesticides, simple operation, natural and cheapness, etc.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] One of the technical solutions of the present invention, a preparation method of a tourmaline composite catalyst, comprises the following steps:

[0009] Adding tourmaline and tannic acid into an acid solution, stirring and reacting to obtain a mixed solution;

[0010] Place the mixed solution in a closed environment and heat it for reaction to obtain the tourmaline composite catalyst.

[0011] The second technical solution of the present invention is a tourmaline composite catalyst prepared by the above preparation method.

[0012] The third technical solution of the present invention is an application of the above tourmaline composite catalyst in activating persulfate to degrade pollutants.

[0013] The fourth technical solution of the present invention is a method for treating wastewater containing pesticides. Mix the above tourmaline composite catalyst with the pesticide-containing wastewater for adsorption of pesticides, and then add persulfate to the reaction system for advanced oxidation reaction.

[0014] The present invention discloses the following technical effects:

[0015] (1) The preparation method provided by the present invention successfully modifies tannic acid on tourmaline through complexation reaction and thermal solvent method to obtain a tourmaline composite catalyst material. Its preparation process is simple, easy to operate, and low in cost.

[0016] (2) In the tourmaline composite catalyst prepared by the present invention, tannic acid combines with Fe in tourmaline through complexation reaction to improve the reaction activity of Fe, and can also serve as a new active site, thereby improving the catalytic performance of the catalyst material; the tourmaline composite catalyst contains an internal electric field, which can not only improve the performance of the catalyst material in activating persulfate, but also promote the reaction between the generated active substances and pollutants.

[0017] (3) Using the tourmaline composite catalyst of the present invention for advanced oxidation reaction of pesticide wastewater has the advantages of simple application method, low cost, high removal rate of pesticides, etc., and can effectively degrade pesticides in wastewater, having good application prospects. Among them, taking imidacloprid as an example, the removal rate of imidacloprid by the tourmaline composite catalyst of the present invention can reach 96.6% within 10 minutes, which is about 6.7 times that of tourmaline (14.3%), and the catalytic efficiency is significantly improved, with faster catalytic efficiency and better removal effect. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1Scanning electron microscope image of the tourmaline composite catalyst (TTC) prepared in Example 1 of the present invention;

[0020] Figure 2 XRD patterns of the tourmaline composite catalyst (TTC) prepared in Example 1 of the present invention and the tourmaline catalyst (TR) in Comparative Example 1;

[0021] Figure 3 Fourier transform infrared spectroscopy patterns of the tourmaline composite catalyst (TTC) prepared in Example 1 of the present invention and the tourmaline catalyst (TR) in Comparative Example 1;

[0022] Figure 4 Electron paramagnetic resonance spectrometer image of the tourmaline composite catalyst (TTC) prepared in Example 1 of the present invention. The probe used is DMPO, and the detection object is superoxide anion;

[0023] Figure 5 Electron paramagnetic resonance spectrometer image of the tourmaline composite catalyst (TTC) prepared in Example 1 of the present invention. The probe used is TEMP, and the detection object is singlet oxygen;

[0024] Figure 6 Electron paramagnetic resonance spectrometer image of the tourmaline composite catalyst (TTC) prepared in Example 1 of the present invention. The probe used is DMPO, and the detection object is hydroxyl radical;

[0025] Figure 7 Schematic diagram showing the relationship between the concentration of imidacloprid and the catalytic time during the activation of persulfate by the tourmaline composite catalyst (TTC) prepared in Example 1 of the present invention and the tourmaline catalyst (TR) in Comparative Example 1;

[0026] Figure 8 Degradation effect diagram of imidacloprid by the tourmaline composite catalyst prepared with different amounts of tannic acid in Example 2;

[0027] Figure 9 Degradation effect diagram of imidacloprid by the tourmaline composite catalyst prepared with different acetic acid concentrations in Example 3;

[0028] Figure 10 Degradation effect diagram of different insecticides by the tourmaline composite catalyst (TTC) prepared in Example 1 of the present invention. Detailed implementation mode

[0029] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0030] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0031] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0032] Without departing from the scope or spirit of the present invention, various improvements and variations can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0033] Regarding "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0034] Unless otherwise specified, room temperature in the present invention means 15 - 30 °C.

[0035] The present invention utilizes the Fe contained in natural mineral tourmaline itself to activate persulfate for advanced oxidation reaction. Natural organic matter tannic acid can undergo a complexation reaction with Fe to change the chemical coordination environment of Fe in tourmaline, thereby enhancing the ability of tourmaline to activate persulfate. The tourmaline composite catalyst of the present invention can be carried out at normal temperature and pressure, and has the advantages of high persulfate utilization rate, high removal rate of pesticides, and simple operation.

[0036] The first aspect of the present invention provides a preparation method of a tourmaline composite catalyst, comprising the following steps:

[0037] Add tourmaline and tannic acid to an acid solution, stir and react to obtain a mixed solution;

[0038] Place the mixed solution in a closed environment, heat and react to obtain the tourmaline composite catalyst.

[0039] In a preferred embodiment of the present invention, before adding tourmaline and tannic acid to the acid solution, it further includes a step of grinding the tourmaline.

[0040] In a preferred embodiment of the present invention, the acid solution is an acetic acid solution; the volume concentration of the acetic acid solution is 1-20% (more preferably 5-20%). The present invention does not make special limitations on the dosage of the acetic acid solution, and the dosage can sufficiently immerse the tourmaline to meet the reaction conditions of the tourmaline and tannic acid. For example, the dosage of the acetic acid solution is 50 mL.

[0041] In a preferred embodiment of the present invention, the mass ratio of the tourmaline to the tannic acid is 100∶1-20.

[0042] In a preferred embodiment of the present invention, the temperature of the stirring reaction is room temperature and the time is 12 h.

[0043] In a preferred embodiment of the present invention, the temperature of the reaction is 120-180 °C (specifically, it can be 120 °C, 140 °C, 160 °C, 180 °C, or any value between the aforementioned two values), the time is 4-8 h (specifically, it can be 4 h, 5 h, 6 h, 7 h, 8 h), and the heating rate is 10 °C / min.

[0044] In a preferred embodiment of the present invention, after the reaction, it further includes a step of collecting the solid product and washing and drying the collected solid product.

[0045] The second aspect of the present invention provides a tourmaline composite catalyst prepared by the above preparation method. In this tourmaline composite catalyst, the total content of tannic acid in the tourmaline composite catalyst is 1-20 wt%.

[0046] The third aspect of the present invention provides an application of the above tourmaline composite catalyst in activating persulfate to degrade pollutants.

[0047] In a preferred embodiment of the present invention, the pollutant is an insecticide.

[0048] In a preferred embodiment of the present invention, the insecticide is imidacloprid or a neonicotinoid insecticide; the neonicotinoid insecticide is nitenpyram, clothianidin or dinotefuran.

[0049] The fourth aspect of the present invention provides a method for treating wastewater containing insecticides. The above tourmaline composite catalyst is mixed with the wastewater containing insecticides for adsorption of the insecticide, and then persulfate is added to the reaction system for advanced oxidation reaction.

[0050] In a preferred embodiment of the present invention, the wastewater containing pesticides is imidacloprid-containing wastewater or wastewater containing neonicotinoid pesticides; the wastewater containing neonicotinoid pesticides includes, but is not limited to, nitenpyram-containing wastewater, clothianidin-containing wastewater or dinotefuran-containing wastewater.

[0051] In a preferred embodiment of the present invention, the adsorption time is 25 - 35 min, specifically it can be 25 min, 27 min, 30 min, 35 min, or any value between the aforementioned two values.

[0052] In a preferred embodiment of the present invention, the temperature of the advanced oxidation reaction is 5 - 40 °C, specifically it can be 5 °C, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, or any value between the aforementioned two values, and the time is 10 - 30 min, specifically it can be 10 min, 15 min, 20 min, 25 min, 30 min, or any value between the aforementioned two values.

[0053] In a preferred embodiment of the present invention, persulfate is added to make the concentration of persulfate in the reaction system 200 mg / L.

[0054] In the present invention, the dosage of the pesticide in the wastewater and the tourmaline composite catalyst is not particularly limited. By applying the tourmaline composite catalyst, advanced oxidation of the pesticide can be carried out for degradation and removal. Preferably, the weight ratio of the tourmaline composite catalyst to the pesticide is 10 - 50:1; the concentration of the pesticide in the pesticide wastewater can be adjusted to 1 - 15 mg / L with water, and then the addition amount of the tourmaline composite catalyst in the wastewater is 10 - 750 mg / L. The inventors found that in this preferred embodiment, the efficiency of the catalytic reaction for removing pesticides can be effectively improved.

[0055] The technical solutions of the present invention, unless otherwise specified, are all conventional solutions in the art.

[0056] In the following examples, the concentration of imidacloprid was detected by a high performance liquid chromatograph (mobile phase: methanol: water = 45:55, flow rate 1 mL / min, column temperature 30 °C, monitoring wavelength 260 nm). The high performance liquid chromatograph was purchased from Agilent Technologies, and the instrument model was 1290 Infinity II; the scanning electron microscope was purchased from Hitachi Regulus81; the Fourier transform infrared spectrometer was purchased from Thermo Scientific, USA, and the instrument model was Nicolet iS20; the electron paramagnetic resonance spectrometer was purchased from Bruker, Germany, and the instrument model was EMXplus-6 / 1; the XRD analyzer was purchased from Bruker, and the instrument model was D8 advance.

[0057] In the following examples, unless otherwise specified, the raw materials and instruments used are all conventional commercially available products. Among them, tannic acid and acetic acid were both purchased from Aladdin. The pesticide wastewater used the imidacloprid solution prepared by ourselves as the simulated wastewater, and imidacloprid was purchased from Aladdin.

[0058] In the following examples, unless otherwise specified, the data obtained are all the averages of more than three repeated experiments, and the room temperature is 25 ± 5 °C.

[0059] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with examples, but the content of the present invention is not limited to the following examples.

[0060] Example 1

[0061] (1) Grind tourmaline thoroughly to obtain tourmaline powder;

[0062] (2) Add 100 mg of tourmaline powder and 10 mg of tannic acid to 50 mL of 10% (v / v) acetic acid solution and stir at room temperature for 12 h to obtain a mixed solution;

[0063] (3) Place the mixed solution in a high-pressure reactor and heat it in an oven at 140 °C for 6 h. After cooling, wash it with ultrapure water and dry it to obtain a tourmaline composite catalyst (TTC).

[0064] Comparative Example 1

[0065] (1) Grind tourmaline thoroughly to obtain tourmaline powder;

[0066] (2) Add 100 mg of tourmaline powder to 50 mL of 10% (v / v) acetic acid solution and stir at room temperature for 12 h. After washing with ultrapure water and drying, obtain a tourmaline catalyst (TR).

[0067] Example 2

[0068] (1) Grind tourmaline thoroughly to obtain tourmaline powder;

[0069] (2) Add 100 mg of tourmaline powder and tannic acid (1 mg, 5 mg, 10 mg, 20 mg) to 50 mL of 10% (v / v) acetic acid solution and stir at room temperature for 12 h to obtain a mixed solution;

[0070] (3) Place the mixed solution in a high-pressure reactor and heat it in an oven at 140 °C for 6 h. After cooling, wash it with ultrapure water and dry it to obtain a tourmaline composite catalyst. (When the dosage of tannic acid is 10 mg, the prepared material is named TTC. When the dosage of tannic acid is 1, 5, 20 mg, the prepared materials are named TTC-x, where x represents the addition amount of tannic acid)

[0071] Example 3

[0072] (1) Grind tourmaline sufficiently to obtain tourmaline powder;

[0073] (2) Add 100 mg of tourmaline powder and 10 mg of tannic acid to 50 mL of acetic acid solution (5% (v / v), 10% (v / v), 15% (v / v), 20% (v / v)) and stir at room temperature for 12 h to obtain a mixed solution;

[0074] (3) Place the mixed solution in a high-pressure reactor and heat it in an oven at 140 °C for 6 h. After cooling, wash it with ultrapure water and dry it to obtain a tourmaline composite catalyst. (The material prepared when the concentration of acetic acid solution is 10% is TTC, and the materials prepared at other different acetic acid concentrations are named TTC(y), where y is the concentration of acetic acid solution)

[0075] Effect verification example

[0076] 1. Perform scanning electron microscopy (SEM) analysis on the tourmaline composite catalyst (TTC) prepared in Example 1. The results are as Figure 1 shown. It can be seen from Figure 1 that the TTC prepared in Example 1 has a rough block structure on the surface.

[0077] 2. Perform XRD analysis on the tourmaline composite catalyst (TTC) prepared in Example 1 and the tourmaline catalyst (TR) prepared in Comparative Example 1 respectively. The results are as Figure 2 shown. It can be seen from Figure 2 that the TR prepared in Comparative Example 1 shows typical tourmaline diffraction peaks, while the TTC shows diffraction peaks similar to those of TR, indicating that the addition of tannic acid does not destroy the crystal structure of tourmaline, which is of great significance for maintaining the catalytic performance of the composite catalyst.

[0078] 3. Perform Fourier transform infrared spectroscopy (FT-IR) analysis on the tourmaline composite catalyst (TTC) prepared in Example 1 and the tourmaline catalyst (TR) prepared in Comparative Example 1 respectively. The results are as Figure 3 shown. It can be seen from Figure 3 that the TTC shows a spectrum similar to that of TR. However, at 2170 cm -1 the TTC shows a new peak, which is the characteristic peak of C=C and C=O, indicating the successful modification of tannic acid.

[0079] 4. Perform electron paramagnetic resonance spectroscopy (ESR) analysis on the tourmaline composite catalyst (TTC) prepared in Example 1. The results are as Figures 4 - 6 shown. It can be seen from Figures 4 - 6 that the TTC can activate persulfate to generate superoxide anion, singlet oxygen and hydroxyl radical.

[0080] 5. (1) Weigh 10 mg of TTC prepared in Example 1 and TR prepared in Comparative Example 1, and add them to 25 mL of imidacloprid wastewater with an initial concentration of 10 mg / L respectively. After adsorption for 30 min, place them in a catalytic reaction device.

[0081] (2) Add 5 mg of persulfate to the mixed solution obtained in (1) to make the persulfate concentration in the reaction system 200 mg / L, and carry out catalytic reaction for 10 min to complete the treatment of imidacloprid in the wastewater.

[0082] Samples are taken at catalytic reaction times t of 0 min, 2.5 min, 5 min, and 10 min. After filtering with a 0.22 μm filter membrane, the imidacloprid concentration in the solution is detected. The imidacloprid concentration is analyzed and determined by a high-performance liquid chromatograph. Combining with the standard curve, the imidacloprid concentration C corresponding to different reaction times is obtained. According to the formula (D = (C0 - C) / C0 × 100%, where C0 is the initial concentration of imidacloprid), the removal rate D of imidacloprid corresponding to different reaction times is calculated, and the results are as Figure 7 shown.

[0083] It can be Figure 7 seen that the removal rate of imidacloprid by TTC of the present invention can reach 96.6% within 10 min, which is about 6.7 times that of TR (14.3%). The catalytic efficiency is significantly improved, that is, the tourmaline composite catalyst of the present invention has a faster catalytic efficiency and a better imidacloprid removal effect. It can be seen that the tourmaline composite catalyst of the present invention has higher catalytic activity than tourmaline.

[0084] 6. The degradation effects of the catalysts prepared with different amounts of tannic acid in Example 2 and the catalysts prepared with different acetic acid concentrations in Example 3 on imidacloprid were tested according to the operation in 5 of the effect verification example. The results show that when the amount of tannic acid is too high or too low, or the concentration of acetic acid solution is too high or too low, the catalytic performance of the catalyst will be reduced.

[0085] 7. The degradation effects on imidacloprid and other neonicotinoid insecticides (nitenpyram, clothianidin, dinotefuran) were tested according to the operation in 5 of the effect verification example. It can be Figure 10 seen that TTC of the present invention has general applicability for the degradation of neonicotinoid insecticides.

[0086] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a tourmaline composite catalyst, characterized in that, It includes the following steps: Add tourmaline and tannic acid into an acid solution, stir and react to obtain a mixed solution; Place the mixed solution in a closed environment, heat and react to obtain the tourmaline composite catalyst.

2. The preparation method of the tourmaline composite catalyst according to claim 1, characterized in that, Before adding tourmaline and tannic acid into the acid solution, it also includes the step of grinding the tourmaline.

3. The preparation method of the tourmaline composite catalyst according to claim 1, characterized in that, The acid solution is an acetic acid solution; the volume concentration of the acetic acid solution is 1-20%.

4. The preparation method of the tourmaline composite catalyst according to claim 1, characterized in that, The mass ratio of the tourmaline to the tannic acid is 100∶1-20.

5. The preparation method of the tourmaline composite catalyst according to claim 1, characterized in that, The temperature of the stirring reaction is room temperature and the time is 12 h.

6. The preparation method of the tourmaline composite catalyst according to claim 1, wherein The temperature of the reaction is 120-180 °C, the time is 4-8 h, and the heating rate is 10 °C / min.

7. The preparation method of the tourmaline composite catalyst according to claim 1, characterized in that, After the reaction, it also includes the steps of collecting the solid product and washing and drying the collected solid product.

8. A tourmaline composite catalyst prepared by the preparation method according to any one of claims 1-7.

9. An application of the tourmaline composite catalyst according to claim 8 in activating persulfate to degrade pollutants.

10. A method for treating wastewater containing pesticides, characterized in that, Mix the tourmaline composite catalyst according to claim 8 with the pesticide-containing wastewater for adsorption of pesticides, and then add persulfate into the reaction system for advanced oxidation reaction.

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