Synthesis of polyacid-based spinel composite for removal of methylene blue from water

Abstract

The application discloses a kind of synthesis methods of polyacid-based spinel composite for removing methylene blue in water, belong to the technical field of pollutant processing.The chemical formula of the polyacid-based spinel composite for removing methylene blue in water of the application is xHPMoV / MnCo2O4-NH2.The composite of the application has both adsorption and degradation functions, and has excellent adsorption and catalytic degradation performance, and the reaction conditions are mild, the efficiency is higher, and the shortcomings of the existing catalysts, such as single function and long adsorption equilibrium time, are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of pollutant treatment, in particular to a method for synthesizing a polyacid-based spinel composite material for removing methylene blue from water. Background Art

[0002] Methylene blue is a common cationic dye with poor biodegradability and high toxicity. With its widespread use in textiles, papermaking, pharmaceuticals, and cosmetics, the amount of wastewater containing methylene blue has increased annually, leading to increasingly serious water pollution. Furthermore, methylene blue can easily accumulate in the human body through water and the food chain, and even trace levels can cause various illnesses such as dizziness, vomiting, shock, tissue necrosis, and even cancer. Therefore, the effective removal of methylene blue from water is crucial.

[0003] Traditional methods for removing methylene blue from water include biological, physical (adsorption, flocculation, membrane filtration), and chemical (oxidation, photocatalysis), with adsorption and oxidation being the most common. Adsorption is simple, efficient, and energy-efficient. Methylene blue adsorbents often possess a high specific surface area and a uniform pore size distribution, which allow them to adsorb methylene blue from water and achieve removal. For example, Tang Chaochun et al. recycled mineralized waste, then modified it with roasting and alkali activation to produce a methylene blue adsorbent. The adsorption rate reached 96.27% in 200 mL of a 50 mg / L methylene blue solution within one hour (Chinese Patent CN107930573A). Liang Yufeng et al. also used activated carbon derived from mangosteen shells to adsorb methylene blue, achieving 99.5% adsorption in 60 minutes (Chinese Patent CN107335402A). The common oxidation method involves combining an oxidant with a catalyst. Free radicals are generated during the reaction, degrading the dye molecules into non-polluting substances such as H₂O and CO₂. Oxidation methods offer the advantages of high efficiency and zero secondary pollution. For example, Song Leshan et al. stirred manganese slag powder with a copper-cerium mixture to obtain a catalyst, which was then calcined to produce a catalyst. Within 2 hours, the catalyst, in the presence of 0.3 mL of H₂O₂, could degrade 99.9% of methylene blue (CM) (Chinese Patent CN108273516A). Qin Miao et al. used nano-CuO / Fe₃O₄ to activate H₂O₂ to degrade CM. When 0.20 g of the catalyst and 7.0 mL of H₂O₂ were added to 100 mL of a 10 mg / L CM solution, 95.0% of CM was degraded within 6 hours (Chinese Patent CN116393129A). Although the above substances can achieve good adsorption and degradation of methylene blue, the adsorption and degradation time is generally long, the synthesis method is relatively complicated, and the processing cost is high. It is impossible to achieve the effect of both adsorbing and degrading methylene blue. Therefore, it is necessary to synthesize a catalyst with low cost, simple operation and excellent adsorption and degradation performance. SUMMARY

[0004] The present application aims to provide a method for synthesizing a polyoxometalate-based spinel composite material for removing methylene blue in water to solve the problems existing in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides the following solutions.

[0006] One of the technical solutions of the present application is a polyoxometalate-based spinel composite material for removing methylene blue in water, and the chemical formula of the composite material is xHPMoV / MnCo2O4-NH2.

[0007] Wherein x is the loading amount of HPMoV in the composite material; the loading amount is 5-50wt.%.

[0008] Further, the loading amount is 10-50wt.%.

[0009] The second technical solution of the present application is a method for synthesizing the above-mentioned polyoxometalate-based spinel composite material, comprising the following steps.

[0010] MnCo2O4 is added to water to dissolve, then organic solvent and amino silane are added, and reflux reaction is performed to obtain MnCo2O4-NH2.

[0011] According to the loading amount, H5[PMo 10 V2O 40 ] is added to the solution of MnCo2O4-NH2 in the form of a solution, and reflux reaction is performed to obtain the composite material.

[0012] Changing the type of organic ligand (polyoxometalate) cannot synthesize the composite material with the same structure (known from infrared spectrum analysis) as the present application, and cannot obtain the composite material with both adsorption and degradation performance.

[0013] Further, the method for synthesizing MnCo2O4 comprises the following steps: dissolving cobalt salt and manganese salt in water, then adding ammonium salt solution dropwise, filtering, drying, and calcining after complete mixing to obtain MnCo2O4.

[0014] Further, the heating rate of calcination is 5℃ / min, the temperature is 500℃, and the time is 6h.

[0015] The cobalt salt includes cobalt acetate; the manganese salt includes manganese acetate; and the ammonium salt solution includes ammonium carbonate solution.

[0016] Furthermore, when synthesizing MnCo2O4-NH2, the reflux reaction temperature is 80°C and the time is 24 hours; the organic solvent includes ethanol (C2H5OH); and the aminosilane includes 3-aminopropyltriethoxysilane (APTES).

[0017] Furthermore, when synthesizing the composite material, the reflux reaction temperature is 120° C. and the time is 20 h.

[0018] The third technical solution of the present invention: an application of the above-mentioned polyacid-based spinel composite material in the removal of methylene blue.

[0019] Furthermore, the removal method specifically includes: adding the composite material into a solution containing methylene blue to carry out a removal reaction.

[0020] Furthermore, during the removal reaction, the mass ratio of the composite material to methylene blue is 10-55:0.5; the reaction temperature is 25° C., the reaction time is 0.25-5 min; and the reaction pH is 1-9.

[0021] Furthermore, when performing the removal reaction, the reaction temperature is 25° C., the reaction time is 0.5 to 4 minutes, and the pH of the reaction is 5.

[0022] Furthermore, the removal method further includes adding an oxidant to the solution containing methylene blue and continuing the reaction.

[0023] Furthermore, when the reaction is continued, the mass ratio of the composite material, methylene blue and oxidant is 10-55:0.5:10-20; the reaction temperature is 0-25°C, and the time is 1-5 minutes; the pH of the reaction is 1-9; and the oxidant includes peroxymonosulfate (PMS).

[0024] Furthermore, when the reaction is continued, the reaction temperature is 20-25° C., the reaction time is 3-5 minutes, and the pH of the reaction is 5.

[0025] Furthermore, after the removal reaction, the composite material is recovered by centrifugation at a rotation speed of 6000 rpm for 5 minutes.

[0026] The present invention discloses the following technical effects:

[0027] (1) The composite material of the present invention has both adsorption and degradation functions, and has excellent adsorption and catalytic degradation performance. In addition, the reaction conditions are mild, the reaction time is short, and the efficiency is high, which overcomes the shortcomings of existing catalysts with single function and long adsorption equilibrium time.

[0028] (2) The composite material of the present application has simple synthesis steps, low synthesis cost, environmental protection, non-toxicity (no pollution), easy implementation, and can be recycled through simple centrifugation operation, and has stable and excellent performance.

[0029] (3) The present application combines HPMoV with spinel oxides (MnCo2O4-NH2) to obtain a composite material with super-high removal efficiency, which can completely remove methylene blue in water within 4 min. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0031] Figure 1 The infrared spectra of the polyoxometalate (HPMoV) synthesized in the present application, MnCo2O4 synthesized in Example 1, MnCo2O4-NH2, 10% HPMoV / MnCo2O4-NH2, and 37.5% HPMoV / MnCo2O4-NH2 synthesized in Example 3;

[0032] Figure 2 The XPS graphs of the polyoxometalate (HPMoV) synthesized in the present application, MnCo2O4 synthesized in Example 1, MnCo2O4-NH2, 10% HPMoV / MnCo2O4-NH2, and 37.5% HPMoV / MnCo2O4-NH2 synthesized in Example 3;

[0033] Figure 3 The graph of the removal effect of methylene blue in water with time for 50 mg of PMS (persulfate), 50 mg of MnCo2O4 synthesized in Example 1, 50 mg of MnCo2O4-NH2 synthesized in Example 1, 50 mg of HPMoV, 50 mg of 37.5% HPMoV / MnCo2O4-NH2 synthesized in Example 3, 50 mg of 10% HPMoV / MnCo2O4-NH2 synthesized in Example 1, and 50 mg of the composite material (MnCo2O4 / HPMoV) synthesized in Comparative Example 1;

[0034] Figure 4 The methylene blue standard concentration curve;

[0035] Figure 5Graph showing the results of removing methylene blue from 5% HPMoV / MnCo2O4-NH2, 10% HPMoV / MnCo2O4-NH2, 20% HPMoV / MnCo2O4-NH2, 30% HPMoV / MnCo2O4-NH2, 37.5% HPMoV / MnCo2O4-NH2, and 50% HPMoV / MnCo2O4-NH2 synthesized in Examples 1 to 6 of the present invention;

[0036] Figure 6 This is a graph showing the effect of 37.5% HPMoV / MnCo2O4-NH2 synthesized in Example 3 of the present invention on removing methylene blue from water over time;

[0037] Figure 7 This is a graph showing the removal of methylene blue by different dosages of 10% HPMoV / MnCo2O4-NH2 synthesized in Example 1 of the present invention;

[0038] Figure 8 This is the result of removing methylene blue with different dosages of oxidant PMS;

[0039] Figure 9 The figure shows the removal results of methylene blue at different pH values;

[0040] Figure 10 The removal results of methylene blue at different reaction temperatures;

[0041] Figure 11 This is a graph showing the change in the removal effect of methylene blue by 10% HPMoV / MnCo2O4-NH2 synthesized in Example 1 of the present invention over time. DETAILED DESCRIPTION

[0042] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0043] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0044] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice 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 associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0045] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0046] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0047] All “parts” described in the following examples are “parts by mass”.

[0048] The polyoxometalates (H5[PMo 10 V2O 40 ], the synthesis method of HPMoV) is:

[0049] Completely dissolve 2.44 g of sodium metavanadate in 10 mL of boiling water, then add 10 mL of Na2HPO4 aqueous solution (the preparation method of Na2HPO4 aqueous solution is as follows: dissolve 0.71 g of Na2HPO4·12H2O in water and dilute to 10 mL). Mix and stir for 10 minutes, then cool to room temperature. Then add 0.5 mL of concentrated sulfuric acid and mix well to obtain red solution A.

[0050] Dissolve 12.1 g of Na2MoO4·2H2O in 20 mL of water to obtain solution B. Add solution B to solution A and stir vigorously until completely mixed. Then slowly add 8.5 mL of concentrated sulfuric acid dropwise. After cooling to room temperature, add 50 mL of ether for extraction. Collect the intermediate layer, transfer it to a beaker, add a small amount of water, heat in a water bath, and dry it to obtain HPMoV.

[0051] Example 1

[0052] A method for synthesizing a polyacid-based spinel composite material for removing methylene blue from water:

[0053] (1) 4.98 g (CH3COO)2Co·4H2O and 2.45 g (CH3COO)2Mn·4H2O were added to 40 mL of deionized water and stirred for 30 min to obtain solution A; 5.76 g (NH4)2CO3 was dissolved in 40 mL of deionized water to obtain solution B; solution B was then slowly added dropwise to solution A, and after complete mixing, the mixed solution was filtered, and the solid obtained after filtration was dried at 60°C for 24 h and then calcined. The calcination was carried out in an air atmosphere at a heating rate of 5°C / min. When the temperature reached 500°C, it was kept at this temperature for 6 h, and then naturally cooled to room temperature to obtain MnCo2O4.

[0054] (2) Dissolve 2 g of MnCo2O4 in 80 mL of deionized water, ultrasonicate for 40 min, add 250 mL of C2H5OH (ethanol) and 10 mL of APTES (3-aminopropyltriethoxysilane), and stir for 50 min. Then, reflux at 80 °C for 24 h. Turn off the reflux, cool to room temperature, filter, wash with anhydrous ethanol, and dry for 24 h to obtain MnCo2O4-NH2.

[0055] (3) 0.6 g of MnCo2O4-NH2 was dissolved in 30 mL of CH3CN (acetonitrile) to obtain solution C; 0.07 g of HPMoV was dissolved in 30 mL of CH3CN to obtain solution D; then solution D was slowly added dropwise to solution C, and after complete mixing, the mixture was condensed and refluxed at 120°C for 20 h. After turning off the reflux and cooling to room temperature, the mixture was filtered, washed with anhydrous ethanol, and dried for 24 h to obtain 10% HPMoV / MnCo2O4-NH2 (a polyacid-based spinel composite material, the theoretical loading of HPMoV in the composite material is 10 wt.%, and the actual loading is 7.7 wt.%).

[0056] Example 2

[0057] The same as Example 1, except that the amount of HPMoV was adjusted to 0.03 g, to obtain 5% HPMoV / MnCo2O4-NH2 (a polyacid-based spinel composite material, with a theoretical loading of HPMoV in the composite material of 5 wt.%, and an actual loading of 3.2 wt.%).

[0058] Example 3

[0059] The same as Example 1, except that the amount of HPMoV was adjusted to 0.36 g, to obtain 37.5% HPMoV / MnCo2O4-NH2 (a polyacid-based spinel composite material, with a theoretical loading of HPMoV in the composite material of 37.5 wt.%, and an actual loading of 36.8 wt.%).

[0060] Example 4

[0061] The same as Example 1, except that the amount of HPMoV was adjusted to 0.15 g, to obtain 20% HPMoV / MnCo2O4-NH2 (a polyacid-based spinel composite material, with a theoretical loading of HPMoV in the composite material of 20 wt.%, and an actual loading of 15.5 wt.%).

[0062] Example 5

[0063] The same as Example 1, except that the amount of HPMoV was adjusted to 0.26 g, to obtain 30% HPMoV / MnCo2O4-NH2 (a polyacid-based spinel composite material, with a theoretical loading of HPMoV in the composite material of 30 wt.%, and an actual loading of 27.7 wt.%).

[0064] Example 6

[0065] The same as Example 1, except that the amount of HPMoV was adjusted to 0.60 g, to obtain 50% HPMoV / MnCo2O4-NH2 (a polyacid-based spinel composite material, with a theoretical loading of HPMoV in the composite material of 50 wt.%, and an actual loading of 37.5 wt.%).

[0066] Comparative Example 1

[0067] (1) 4.98 g (CH3COO)2Co·4H2O and 2.45 g (CH3COO)2Mn·4H2O were added to 40 mL of deionized water and stirred for 30 min to obtain solution A; 5.76 g (NH4)2CO3 was dissolved in 40 mL of deionized water to obtain solution B; solution B was then slowly added dropwise to solution A, and after complete mixing, the mixed solution was filtered, and the solid obtained after filtration was dried at 60°C for 24 h and then calcined. The calcination was carried out in an air atmosphere at a heating rate of 5°C / min. When the temperature reached 500°C, it was kept at this temperature for 6 h, and then naturally cooled to room temperature to obtain MnCo2O4.

[0068] (2) 0.6 g of MnCo2O4 was dissolved in 30 mL of CH3CN (acetonitrile) to obtain solution C; 0.07 g of HPMoV was dissolved in 30 mL of CH3CN to obtain solution D; then solution D was slowly added dropwise to solution C, and after complete mixing, the mixture was condensed and refluxed at 120°C for 20 h. After turning off the reflux and cooling to room temperature, the mixture was filtered, washed with anhydrous ethanol, and dried for 24 h to obtain a composite material.

[0069] The method of this comparative example cannot achieve effective loading of HPMoV, and the loaded HPMoV is not strong.

[0070] Comparative Example 2

[0071] Same as Example 1, except that HPMoV is replaced by phosphomolybdic acid.

[0072] Take a 50mL beaker and add 50mL of 10mg / L methylene blue solution in sequence. Take 50mg of the composite material synthesized in this comparative example and add it to the beaker containing the methylene blue solution. The reaction is shaken at a temperature of 25°C (room temperature) and pH = 5 for 2 minutes. Samples are taken and the absorbance of the solution is measured using a UV-visible spectrophotometer (664nm). The removal rate of methylene blue is calculated to be only 22%.

[0073] Take a 50mL beaker and add 50mL of a 10mg / L methylene blue solution. Take 50mg of the composite material synthesized in this comparative example and add it to the beaker containing the methylene blue solution. After shaking and reacting for 30min at a temperature of 25°C (room temperature) and a pH of 5, 15mg of the oxidant PMS (peroxymonosulfate) was added to the beaker for a catalytic oxidation removal experiment. After shaking and reacting for 4min, a sample was taken and the absorbance of the solution was tested using a UV-visible spectrophotometer (664nm). The methylene blue removal rate was calculated to be 82.3%.

[0074] The composite material synthesized in this comparative example has poorer performance than the HPMoV / MnCo2O4-NH2 composite material. Therefore, it can be concluded that only when MnCo2O4-NH2 is combined with HPMoV can a polyacid-based spinel composite material for removing methylene blue from water be prepared.

[0075] Effect Example 1

[0076] The infrared spectra of the polyoxometalate (HPMoV) synthesized in the present invention, MnCo2O4, MnCo2O4-NH2, 10% HPMoV / MnCo2O4-NH2 synthesized in Example 1, and 37.5% HPMoV / MnCo2O4-NH2 synthesized in Example 3 were measured. The results are shown in FIG. Figure 1 .

[0077] from Figure 1 It can be seen from the infrared spectrum of MnCo2O4 that at 650cm -1 The corresponding tetrahedral unit of spinel structure is Co 2+ -O bond stretching vibration, 551 cm -1 Corresponding to the spinel structure Co 3+ -O octahedral unit at 485cm -1 At the position corresponding to the spinel octahedron, Mn 3+ (Mn 4+ )-O. In the HPMoV spectrum, 1048cm -1 , 950cm -1 , 875cm-1 and 770cm -1 The stretching vibration peaks of PO, Mo-O, and Mo-O-Mo corners and edges are respectively assigned to the shared bridging oxygen. 10% HPMoV / MnCo2O4-NH2 and 37.5% HPMoV / MnCo2O4-NH2 are at 649cm -1 (648cm -1 )、551cm -1 (549cm -1 ) and 483cm -1 (482cm -1 ) appears at 2+ -O、Mn 3+ (Mn 4+ )-O、Co 3+ -O characteristic absorption peak at 1046cm -1 、947cm -1 、871cm -1 and 770cm -1 The characteristic peaks of PO, Mo-O and Mo-O-Mo appear nearby, which indicates that HPMoV is successfully combined with MnCo2O4.

[0078] Effect Example 2

[0079] The XPS patterns of the polyoxometalates (HPMoV) synthesized by the present invention, MnCo2O4, MnCo2O4-NH2, 10% HPMoV / MnCo2O4-NH2 synthesized in Example 1, and 37.5% HPMoV / MnCo2O4-NH2 synthesized in Example 3 (the chemical state and surface species composition of all samples were identified by XPS spectroscopy) are shown in FIG. Figure 2 .

[0080] from Figure 2It can be seen that in MnCo2O4, the absorption peaks at 780.10 eV, 641.80 eV and 531.14 eV are attributed to Co 2p, Mn 2p and O 1s, respectively. In MnCo2O4-NH2, N 1s absorption peak appears at 399.18 eV, indicating that MnCo2O4 is successfully combined with -NH2; in 10% HPMoV / MnCo2O4-NH2 and 37.5% HPMoV / MnCo2O4-NH2, the absorption peaks of MnCo2O4 and HPMoV appear at 780.39 eV (Co 2p), 642.11 eV (Mn 2p), 153.54 eV (P 2p), 232.89 eV (Mo 3d) and 517.62 eV (V2p), respectively. The above results show that HPMoV and MnCo2O4 are successfully combined in 10% HPMoV / MnCo2O4-NH2 and 37.5% HPMoV / MnCo2O4-NH2.

[0081] Example 3

[0082] Take 7 100 mL beakers and add 50 mL of methylene blue solution with a concentration of 10 mg / L. Take 50 mg of PMS (peroxymonosulfate), 50 mg of MnCo2O4 synthesized in Example 1, 50 mg of MnCo2O4-NH2 synthesized in Example 1, 50 mg of HPMoV, 50 mg of 37.5% HPMoV / MnCo2O4-NH2 synthesized in Example 3, 50 mg of 10% HPMoV / MnCo2O4-NH2 synthesized in Example 1, and 50 mg of the composite material synthesized in Comparative Example 1 (MnCo2O4 / HPMoV) are added to the beakers containing the methylene blue solution. The methylene blue oscillation reaction is carried out at a temperature of 25°C (room temperature) and pH = 5 for 30 min. The absorbance of the solution (664 nm) is tested using a UV-visible spectrophotometer, the removal effect of methylene blue is compared, and the removal rate is calculated (see Table 1 and Figure 3 ); and the catalyst is recovered by centrifugation (speed of 6000 rpm for 5 min).

[0083] According to different methylene blue concentrations and their corresponding absorbances, the relationship between absorbance and concentration is obtained, and thus the final removal performance of the composite material is obtained. The standard curve formula is y = 95.54286x + 18.28571. See Figure 4 .

[0084] Table 1

[0085]

[0086] From Figure 3From Table 2 and

[0087] Effect Example 4

[0088] Test of different composite materials for removing methylene blue:

[0089] Take 6 50mL beakers, add 50mL methylene blue solution with a concentration of 10mg / L, take 50mg of 10% HPMoV / MnCo2O4-NH2, 5% HPMoV / MnCo2O4-NH2, 37.5% HPMoV / MnCo2O4-NH2, 20% HPMoV / MnCo2O4-NH2, 30% HPMoV / MnCo2O4-NH2, 50% HPMoV / MnCo2O4-NH2 synthesized in Examples 1-6 respectively, and add them into the beakers containing the methylene blue solution, shake the reaction for 2min under the condition of a temperature of 25℃ (room temperature) and pH=5, take samples, use a UV-visible spectrophotometer to test the absorbance of the solution (664nm), and recover the catalyst by centrifugation (speed of 6000rpm, time of 5min), and calculate the removal rate, the results are shown in Table 2 and Figure 5 .

[0090] Table 2

[0091]

[0092] From Table 2 and Figure 5 it can be seen that 37.5% HPMoV / MnCo2O4-NH2 has the highest methylene blue removal rate compared to other composite materials with different loadings of polyoxometalates, and the removal rate has reached 99.4% at 2min.

[0093] The reason for the decrease in the removal rate of 50% HPMoV / MnCo2O4-NH2 at 2min is that the loading of HPMoV has reached saturation, and the surface is agglomerated, affecting the performance of the active sites.

[0094] Effect Example 5

[0095] Effect of methylene blue removal with reaction time:

[0096] Take a 50mL beaker and add 50mL of 10mg / L methylene blue solution. Take 50mg of 37.5% HPMoV / MnCo2O4-NH2 synthesized in Example 3 and add it to the beaker containing methylene blue solution. The reaction is shaken at 25°C (room temperature) and pH = 5 for 0.25min, 0.5min, 1min, 2min, 3min, 4min, and 5min. Samples are taken at different times and the absorbance of the solution is tested using a UV-visible spectrophotometer (664nm). After the reaction, the composite material is recovered by centrifugation (speed of 6000rpm, time for 5min) and the removal rate is calculated. The results are shown in Table 3 and Figure 6 .

[0097] Table 3

[0098]

[0099] From Table 3 and Figure 6 It can be seen that the removal rate of 37.5% HPMoV / MnCo2O4-NH2 (50 mg) for 50 mL of 10 mg / L methylene blue can reach 99.4% in 2 minutes, and the efficiency reaches 100.0% in 4 minutes. Therefore, 37.5% HPMoV / MnCo2O4-NH2 is an excellent remover for removing methylene blue.

[0100] Effect Example 6

[0101] As shown in Table 1, the 10% HPMoV / MnCo2O4-NH2 synthesized in Example 1 had a poor effect on removing methylene blue from water. Therefore, based on this, the 10% HPMoV / MnCo2O4-NH2 composite was added with an oxidant to test its catalytic oxidation effect on removing methylene blue. The specific method is as follows:

[0102] Take 5 50mL beakers and add 50mL of 10mg / L methylene blue solution. Take 10, 25, 40, 50, and 55mg of 10% HPMoV / MnCo2O4-NH2 synthesized in Example 1 and add them to the beaker containing methylene blue solution in sequence. After shaking for 30min at 25°C (room temperature) and pH=5, 15mg of oxidant PMS (permonosulfate) is added to each beaker for catalytic oxidation removal experiment. After shaking for 4min, samples are taken and the absorbance of the solution is tested (664nm) using a UV-visible spectrophotometer. After the reaction, the composite material is recovered by centrifugation (speed of 6000rpm, time of 5min). The reaction conditions and removal results are shown in Table 4 and Figure 7 .

[0103] Table 4

[0104]

[0105] From Table 4 and Figure 7 It can be seen that with the gradual increase in the dosage of 10% HPMoV / MnCo2O4-NH2, the removal effect of methylene blue gradually increases. When the added dosage of the composite material is 50 mg, the removal rate of methylene blue can reach 100.0% in 4 minutes. Subsequently, the removal efficiency remains basically unchanged as the dosage continues to increase.

[0106] Effect Example 7

[0107] Take 7 50mL beakers and add 50mL of 10mg / L methylene blue solution. Add 50mg of 10% HPMoV / MnCo2O4-NH2 synthesized in Example 1 to the beaker containing the methylene blue solution. Shake and react for 30min at 25°C (room temperature) and pH=5. Then, take 10, 12, 13, 14, 15, and 20mg of the oxidant PMS (peroxymonosulfate) and put them into the beaker in sequence. After shaking and reacting for 4min, samples were taken and the absorbance of the solution was tested (664nm) using a UV-visible spectrophotometer. After the reaction, the composite material was recovered by centrifugation (speed of 6000rpm, time for 5min). The reaction conditions and removal results are shown in Tables 5 and 6. Figure 8 .

[0108] Table 5

[0109]

[0110] From Table 5 and Figure 8 It can be seen that with the gradual increase in the amount of PMS, the removal rate of methylene blue is getting higher and higher. After 4 minutes of reaction, when the added dose of oxidant is 15 mg, the removal rate of methylene blue can reach 100.0%. Subsequently, the removal efficiency remains basically unchanged when the amount of oxidant is continued to increase.

[0111] Effect Example 8

[0112] The pH of a 10 mg / L methylene blue solution was adjusted to 1, 3, 7, and 9 using HCl or NaOH. The original pH of the solution was 5. Five 50 mL beakers were added with 50 mL of methylene blue solution having pH values ​​of 1, 3, 5, 7, and 9, respectively. 50 mg of the 10% HPMoV / MnCo2O4-NH2 synthesized in Example 1 was added to the five beakers having different solution pH values. The mixture was shaken and reacted for 30 min at room temperature (25° C.). 15 mg of the oxidant PMS (peroxymonosulfate) was then added. The mixture was shaken and reacted for 4 min before sampling. The absorbance of the solution was measured at 664 nm using a UV-visible spectrophotometer. After the reaction, the composite material was recovered by centrifugation (at a speed of 6000 rpm for 5 min). The reaction conditions and removal results are shown in Tables 6 and 7. Figure 9 .

[0113] Table 6

[0114]

[0115]

[0116] From Table 6 and Figure 9 It can be seen from the figures that the composite material of the present invention can achieve efficient removal of methylene blue at pH 1 to 9, so there is no need to adjust the pH value during the removal of methylene blue.

[0117] Effect Example 9

[0118] Take 6 50mL beakers and add 50mL of 10mg / L methylene blue solution. Then take 50mg of 10% HPMoV / MnCo2O4-NH2 synthesized in Example 1 and add it to the beaker containing methylene blue solution. Shake and react for 30min. Then add 15mg of oxidant PMS (peroxymonosulfate). Adjust the reaction temperature to 0, 5, 10, 15, 20, and 25°C, shake and react for 4min at pH = 5, then take samples. Use UV-visible spectrophotometer to test the absorbance of the solution (664nm). After the reaction, centrifuge (speed of 6000rpm, time for 5min) to recover the composite material. The reaction conditions and removal results are shown in Table 7 and Figure 10 .

[0119] Table 7

[0120]

[0121] From Table 7 and Figure 10 It can be seen that at 25°C (room temperature), the 10% HPMoV / MnCo2O4-NH2 composite material has the best effect in removing methylene blue, reaching 100.0% within 4 minutes.

[0122] Effect Example 10

[0123] Take a 50mL beaker and add 50mL of 10mg / L methylene blue solution. Take 50mg of 10% HPMoV / MnCo2O4-NH2 synthesized in Example 1 and add it to the beaker containing methylene blue solution. Shake and react for 30min at 25°C (room temperature) and pH=5. Then add 15mg of oxidant PMS (peroxymonosulfate). Samples are taken at different times and the absorbance of the solution is measured using a UV-visible spectrophotometer (664nm). After the reaction, the composite material is recovered by centrifugation (speed of 6000rpm, time of 5min) and the removal rate is calculated. The reaction conditions and removal results are shown in Table 8 and Figure 11 .

[0124] Table 8

[0125]

[0126] From Table 8 and Figure 11 It can be seen that when 50 mg of 10% HPMoV / MnCo2O4-NH2 is at 25°C (room temperature), the solution pH is not adjusted, and the amount of oxidant is 15 mg, methylene blue can be completely oxidized and removed within 4 minutes.

[0127] The above removal rates of the present invention are the average results of three repetitions.

[0128] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A polyacid-based spinel composite material for removing methylene blue from water, characterized in that: The chemical formula of the composite material is: xHPMoV / MnCo2O4-NH2; Wherein x is the loading amount of HPMoV in the composite material; the loading amount is 5 to 50 wt.%; The synthesis method of the polyacid-based spinel composite material for removing methylene blue from water comprises the following steps: MnCo2O4 is added into water and dissolved, and then an organic solvent and aminosilane are added and refluxed to obtain MnCo2O4-NH2; According to the load, H5[PMo 10 V2O 40 ] is added dropwise into the MnCo2O4-NH2 solution in the form of a solution, and refluxed to react to obtain the composite material.

2. A method for synthesizing the polyacid-based spinel composite material according to claim 1, characterized in that: The following steps are involved: MnCo2O4 is added into water and dissolved, and then an organic solvent and aminosilane are added and refluxed to obtain MnCo2O4-NH2; According to the load, H5[PMo 10 V2O 40 ] is added dropwise into the MnCo2O4-NH2 solution in the form of a solution, and refluxed to react to obtain the composite material.

3. The synthesis method according to claim 2, characterized in that The synthesis method of MnCo2O4 comprises the following steps: dissolving cobalt salt and manganese salt in water, then dropwise adding ammonium salt solution, mixing completely, filtering, drying, and calcining to obtain the MnCo2O4.

4. The synthesis method according to claim 3, characterized in that The calcination temperature was 500°C for 6 hours at a heating rate of 5°C / min. The cobalt salt includes cobalt acetate; the manganese salt includes manganese acetate; and the ammonium salt solution includes ammonium carbonate solution.

5. The synthesis method according to claim 2, characterized in that When synthesizing MnCo2O4-NH2, the reflux reaction temperature is 80°C and the time is 24 hours; the organic solvent includes ethanol; and the aminosilane includes 3-aminopropyltriethoxysilane.

6. The synthesis method according to claim 2, characterized in that When synthesizing the composite material, the reflux reaction temperature is 120° C. and the time is 20 h.

7. Use of the polyacid-based spinel composite material according to claim 1 in removing methylene blue.

8. The use according to claim 7, characterized in that The removal method specifically includes: adding the composite material into a solution containing methylene blue to carry out a removal reaction.

9. The use according to claim 8, characterized in that The removal method further includes adding an oxidant to the solution containing methylene blue and continuing the reaction.

10. The use according to claim 9, characterized in that The mass ratio of the composite material, methylene blue and oxidant is 10-55:0.5:10-20; the reaction temperature is 0-25°C, the reaction time is 1-5 minutes; the pH value of the reaction is 1-9; and the oxidant includes peroxymonosulfate.

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