Cobalt phosphosilicate tungstate material, preparation method and application thereof

Abstract

The application provides a cobalt phosphosilicotungstate material and a preparation method and application thereof, and the preparation method comprises the following steps: dissolving phosphotungstate in water to obtain solution A; dissolving silicate in the solution A to obtain solution B; dissolving soluble cobalt salt in water to obtain solution C; pouring the solution C into the solution B, adding a phase transfer catalyst, and standing at 25-30 DEG C for 2-12 h to obtain precipitate D; and drying the precipitate D to obtain the cobalt phosphosilicotungstate material. The cobalt phosphosilicotungstate material is added into a Victoria blue B solution with a concentration of 150-350 mg / L, the pH is adjusted to 6-8, and the Victoria blue B is adsorbed by stirring at 20-35 DEG C for 30-70 min. The preparation method is simple, raw materials are easy to obtain, the prepared cobalt phosphosilicotungstate material has good adsorption performance, can be recycled, and can realize industrialized treatment of organic dyes.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial preparation technology, specifically relating to a cobalt phosphosilicate tungstate material, its preparation method, and its application. Background Technology

[0002] Water resources are vital for human survival and development. However, with rapid industrialization and urbanization, water pollution has become increasingly serious. Water pollution not only damages the ecological environment but also threatens human health. Water pollution can be mainly categorized into industrial pollution, agricultural pollution, domestic and industrial pollution, and radioactive pollution. Among these, organic dye pollution from industrial sources primarily originates from emissions from the textile, food, pharmaceutical, paper, and cosmetic industries, and has already caused significant environmental impact.

[0003] Organic dyes are mainly classified into direct dyes, acid dyes, cationic dyes, reactive dyes, and disperse dyes. Victoria Blue B is a basic cationic dye commonly used in dyeing wool, silk, nylon, and acrylic fibers, producing vibrant and long-lasting colors. However, Victoria Blue B also has phototoxic effects and can produce cytotoxicity in mammalian cell lines, posing a significant threat to human health.

[0004] Currently, methods for treating organic dyes are mainly divided into physical, chemical, and biological methods, such as coagulation, flocculation, ion exchange, adsorption, and photocatalytic degradation. Coagulation, flocculation, and ion exchange methods suffer from drawbacks such as low removal efficiency, high cost, complex operation, or difficult pretreatment, limiting their application in wastewater treatment. Adsorption methods have advantages such as simple design, low energy consumption, high adsorption efficiency, low cost, easy recovery, and eco-friendliness, and are considered one of the more mature technologies for treating pollutants in wastewater. However, the materials and reagents used for adsorption, such as activated carbon, diatomaceous earth, and zeolite, still have problems such as small adsorption capacity, easy saturation, frequent replacement, safety hazards, and difficulty in recycling. Summary of the Invention

[0005] To address the above problems, this invention provides a cobalt phosphosilicate tungstate material, its preparation method, and its applications.

[0006] The technical solution adopted to solve the technical problem is to provide a method for preparing cobalt phosphosilicate tungstate material, including the following steps:

[0007] (1) Dissolve phosphotungstate in water to obtain solution A;

[0008] (2) Dissolve silicate in solution A to obtain solution B;

[0009] (3) Dissolve the soluble cobalt salt in water to obtain solution C;

[0010] (4) Pour solution C into solution B, add phase transfer catalyst, and let stand at 25-30℃ for 2-12 hours. Then take the precipitate to obtain precipitate D.

[0011] (5) The precipitate D was dried to constant weight to obtain cobalt phosphosilicate tungstate material.

[0012] The beneficial effects of the above technical solution of the present invention are as follows: cobalt phosphosilicate tungstate material is synthesized by co-precipitation method using phosphotungstate, silicate and soluble cobalt salt as raw materials. The cobalt phosphosilicate tungstate material prepared by this method has large cavities between particles and a loose and rough surface with many adsorption active sites, and has strong adsorption capacity when used as an adsorbent.

[0013] Preferably, the phosphotungsten salt is sodium phosphotungsten; the silicate is sodium silicate; and the soluble cobalt salt is cobalt nitrate hexahydrate.

[0014] Preferably, the mass ratio of sodium phosphotungstate, cobalt nitrate hexahydrate, and sodium silicate is 1:(2-8):(2-8).

[0015] The beneficial effects of the above technical solution of the present invention are as follows: when the mass ratio of sodium phosphotungstate, cobalt nitrate hexahydrate and sodium silicate is 1:(2~8):(2~8), the prepared cobalt phosphotungstate material has a strong adsorption rate and dye removal rate, the material structure is stable and the adsorption performance is strong.

[0016] More preferably, the mass ratio of sodium phosphotungstenate, cobalt nitrate hexahydrate, and sodium silicate is 1:6:5.

[0017] Preferably, the phase transfer catalyst in step (4) is hexadecyltrimethylammonium bromide; the standing temperature is 28°C and the standing time is 8h.

[0018] The beneficial effects of the above technical solution of the present invention are as follows: the cobalt phosphosilicate tungstate material prepared when the coprecipitation temperature is 28℃ and the time is 8h has a strong adsorption rate and dye removal rate, the material structure is stable and the adsorption performance is strong.

[0019] Preferably, the mass ratio of sodium phosphotungstate to phase transfer catalyst is 1:(0.03-0.04).

[0020] The present invention also provides a cobalt phosphosilicate tungstate material prepared by the above preparation method.

[0021] The present invention also provides the application of the above-mentioned cobalt phosphosilicate tungstate material in the adsorption of Victoria Blue B.

[0022] Preferably, the application of cobalt phosphosilicate tungstate material in the adsorption of Victoria Blue B includes the following steps:

[0023] Cobalt phosphosilicate tungstate material was added to a Victoria Blue B solution with a concentration of 150–350 mg / L, the pH was adjusted to 6–8, and the mixture was stirred at 20–35 °C for 30–70 min to adsorb Victoria Blue B.

[0024] The beneficial effects of the preferred technical solution of this invention are as follows: when the concentration of Victoria Blue B solution is 150–350 mg / L, each unit volume of Victoria Blue B in the solution can bind relatively stably to the binding sites on the cobalt phosphosilicate material; under the condition of a temperature of 20–35°C, Victoria Blue B molecules can obtain sufficient activity energy to interact with the active sites of the cobalt phosphosilicate material; under the condition of a pH of 6–8, H… + and OH - Combining them helps reduce H + and OH - The cobalt phosphosilicate tungstate material competes with Victoria Blue B for adsorption at its active sites, increasing the adsorption potential of the material and improving its adsorption capacity for Victoria Blue B. The adsorption rate of Victoria Blue B by the cobalt phosphosilicate tungstate material reaches equilibrium after stirring for 30–70 min.

[0025] More preferably, the ratio of cobalt phosphosilicate tungstate material to Victoria Blue B solution is 3-7 mg: 8-10 mL.

[0026] More preferably, the pH is 7; the stirring temperature is 25°C; and the stirring time is 40 min.

[0027] The present invention has the following beneficial effects:

[0028] (1) The present invention uses sodium phosphotungstenate, cobalt nitrate hexahydrate and sodium silicate as raw materials to synthesize cobalt phosphotungstenate material by co-precipitation method. The raw materials are readily available, the cost is low and the operation is simple.

[0029] (2) The cobalt phosphosilicate tungstate material prepared by the present invention is composed of many nanoparticles stacked together, with large gaps between the particles. The material surface is loose and rough, with many active sites. At the same time, the adsorption process of cobalt phosphosilicate tungstate material on Victoria Blue B is spontaneous, endothermic and entropy-increasing, which can effectively remove Victoria Blue B from aqueous solution.

[0030] (3) The cobalt phosphosilicate tungstate material prepared in this invention has excellent adsorption performance and can be recycled, enabling large-scale industrial processing. Attached Figure Description

[0031] Figure 1 Here is a SEM image of the cobalt phosphosilicate tungstate material prepared in Example 1;

[0032] Figure 2 The image shows the SEM image of the cobalt phosphotungstenate material prepared in Comparative Example 1.

[0033] Figure 3 This is a SEM image of the cobalt phosphosilicate tungstate material after adsorbing Victoria Blue B in Example 1;

[0034] Figure 4 These are the XRD patterns of cobalt phosphotungstenate, cobalt phosphotungstenate, and cobalt silicate materials prepared in Example 1, Comparative Example 1, and Comparative Example 2, respectively.

[0035] Figure 5 The images show the FTIR spectra of the cobalt phosphotungstic acid material prepared in Example 1 before and after adsorption of Victoria Blue B, sodium phosphotungstic acid, the cobalt phosphotungstic acid material prepared in Comparative Example 1, and the cobalt silicate material prepared in Comparative Example 2.

[0036] Figure 6 These are the XPS full spectra of the cobalt phosphotungstic acid material prepared in Example 1 before and after adsorption of Victoria Blue B, and the cobalt phosphotungstic acid material prepared in Comparative Example 1.

[0037] Figure 7 These are P2p XPS images of the cobalt phosphotungstic acid material prepared in Example 1 before and after adsorption of Victoria Blue B, and the cobalt phosphotungstic acid material prepared in Comparative Example 1.

[0038] Figure 8 These are Si 2p XPS images of the cobalt phosphosilicate tungstate material prepared in Example 1 before and after adsorption of Victoria Blue B;

[0039] Figure 9 These are W4f XPS images of the cobalt phosphotungstic acid material prepared in Example 1 before and after adsorption of Victoria Blue B, and the cobalt phosphotungstic acid material prepared in Comparative Example 1.

[0040] Figure 10 These are Co 2p XPS images of the cobalt phosphotungstic acid material prepared in Example 1 before and after adsorption of Victoria Blue B, and the cobalt phosphotungstic acid material prepared in Comparative Example 1.

[0041] Figure 11 These are O1s XPS images of the cobalt phosphotungstic acid material prepared in Example 1 before and after adsorption of Victoria Blue B, and the cobalt phosphotungstic acid material prepared in Comparative Example 1.

[0042] Figure 12 This is a contact angle diagram of the cobalt phosphosilicate tungstate material prepared in Example 1;

[0043] Figure 13 This is a graph showing the effect of ionic strength on the adsorption capacity of cobalt phosphosilicate tungstate for Victoria Blue B.

[0044] Figure 14 These are the absorption spectra of Victoria Blue B, Victoria Blue B in NaCl solution, and Victoria Blue B in NaNO3 solution.

[0045] Figure 15 This is a pseudo-first-order kinetic diagram of the cobalt phosphosilicate tungstate material prepared in Example 1;

[0046] Figure 16 This is a pseudo-second-order kinetic diagram of the cobalt phosphosilicate tungstate material prepared in Example 1;

[0047] Figure 17 This is a fitting diagram of the ion internal diffusion model of the cobalt phosphosilicate tungstate material prepared in Example 1;

[0048] Figure 18 This is a graph of the Langmuir adsorption isotherm model;

[0049] Figure 19 This is a graph of the Freundlich adsorption isotherm model;

[0050] Figure 20 This is a graph of the Temkin adsorption isotherm model;

[0051] Figure 21 The adsorption of InK on the cobalt phosphosilicate tungstate material prepared in Example 1 by Victoria Blue B. 0 Relationship diagram with 1 / T;

[0052] Figure 22 This is a graph showing the regenerative properties of the cobalt phosphosilicate tungstate material prepared in Example 1. Detailed Implementation

[0053] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0054] Example 1

[0055] A cobalt phosphosilicate tungstate material is prepared by the following steps:

[0056] (1) Weigh 1g of sodium phosphotungstenate and dissolve it in 30mL of deionized water to obtain solution A;

[0057] (2) Weigh 5g of sodium silicate and dissolve it in solution A to obtain solution B;

[0058] (3) Weigh 6g of cobalt nitrate hexahydrate and dissolve it in 30mL of deionized water to obtain solution C;

[0059] (4) Pour solution C into solution B, add 0.034 g of hexadecyltrimethylammonium bromide, stir, and let stand at 28°C for 8 h. Then take the precipitate to obtain precipitate D.

[0060] (5) Wash the precipitate D three times with distilled water and centrifuge at 3000 rpm for 15 min. Take the precipitate and dry it at 50°C to constant weight to obtain cobalt phosphosilicate tungstate material.

[0061] The application of the cobalt phosphosilicate tungstate material prepared in this embodiment in the adsorption of Victoria Blue B includes the following steps:

[0062] Weigh 5 mg of cobalt phosphosilicate tungstate material and add it to 9 mL of Victoria Blue B solution with a concentration of 200 mg / L. Adjust the pH to 7 and stir at 25 °C for 40 min to adsorb Victoria Blue B.

[0063] Example 2

[0064] A cobalt phosphosilicate tungstate material is prepared by the following steps:

[0065] (1) Weigh 1g of sodium phosphotungstenate and dissolve it in 30mL of deionized water to obtain solution A;

[0066] (2) Weigh 6g of sodium silicate and dissolve it in solution A to obtain solution B;

[0067] (3) Weigh 2g of cobalt nitrate hexahydrate and dissolve it in 30mL of deionized water to obtain solution C;

[0068] (4) Pour solution C into solution B, add 0.03 g of hexadecyltrimethylammonium bromide, stir, let stand at 25°C for 2 h, and then take the precipitate to obtain precipitate D;

[0069] (5) Wash the precipitate D three times with distilled water and centrifuge at 3000 rpm for 15 min. Take the precipitate and dry it at 45°C to constant weight to obtain cobalt phosphosilicate tungstate material.

[0070] The application of the cobalt phosphosilicate tungstate material prepared in this embodiment in the adsorption of Victoria Blue B includes the following steps:

[0071] Weigh 3 mg of cobalt phosphosilicate tungstate material and add it to 9 mL of Victoria Blue B solution with a concentration of 150 mg / L. Adjust the pH to 3 and stir at 20 °C for 30 min to adsorb Victoria Blue B.

[0072] Example 3

[0073] A cobalt phosphosilicate tungstate material is prepared by the following steps:

[0074] (1) Weigh 1g of sodium phosphotungstenate and dissolve it in 30mL of deionized water to obtain solution A;

[0075] (2) Weigh 6g of sodium silicate and dissolve it in solution A to obtain solution B;

[0076] (3) Weigh 8g of cobalt nitrate hexahydrate and dissolve it in 30mL of deionized water to obtain solution C;

[0077] (4) Pour solution C into solution B, add 0.04 g of hexadecyltrimethylammonium bromide, stir, let stand at 30°C for 6 h, and then take the precipitate to obtain precipitate D;

[0078] (5) Wash the precipitate D three times with distilled water and centrifuge at 3000 rpm for 15 min. Take the precipitate and dry it at 55°C to constant weight to obtain cobalt phosphosilicate tungstate material.

[0079] The application of the cobalt phosphosilicate tungstate material prepared in this embodiment in the adsorption of Victoria Blue B includes the following steps:

[0080] Weigh 4 mg of cobalt phosphosilicate tungstate material and add it to 9 mL of Victoria Blue B solution with a concentration of 250 mg / L. Adjust the pH to 4 and stir at 25 °C for 50 min to adsorb Victoria Blue B.

[0081] Example 4

[0082] A cobalt phosphosilicate tungstate material is prepared by the following steps:

[0083] (1) Weigh 1g of sodium phosphotungstenate and dissolve it in 30mL of deionized water to obtain solution A;

[0084] (2) Weigh 2g of sodium silicate and dissolve it in solution A to obtain solution B;

[0085] (3) Weigh 6g of cobalt nitrate hexahydrate and dissolve it in 30mL of deionized water to obtain solution C;

[0086] (4) Pour solution C into solution B, add 0.034 g of hexadecyltrimethylammonium bromide, stir, and let stand at 28°C for 10 h. Then take the precipitate to obtain precipitate D.

[0087] (5) Wash the precipitate D three times with distilled water and centrifuge at 3000 rpm for 15 min. Take the precipitate and dry it at 50°C to constant weight to obtain cobalt phosphosilicate tungstate material.

[0088] The application of the cobalt phosphosilicate tungstate material prepared in this embodiment in the adsorption of Victoria Blue B includes the following steps:

[0089] Weigh 6 mg of cobalt phosphosilicate tungstate material and add it to 9 mL of Victoria Blue B solution with a concentration of 300 mg / L. Adjust the pH to 5 and stir at 30 °C for 60 min to adsorb Victoria Blue B.

[0090] Example 5

[0091] A cobalt phosphosilicate tungstate material is prepared by the following steps:

[0092] (1) Weigh 1g of sodium phosphotungstenate and dissolve it in 30mL of deionized water to obtain solution A;

[0093] (2) Weigh 8g of sodium silicate and dissolve it in solution A to obtain solution B;

[0094] (3) Weigh 6g of cobalt nitrate hexahydrate and dissolve it in 30mL of deionized water to obtain solution C;

[0095] (4) Pour solution C into solution B, add 0.034 g of hexadecyltrimethylammonium bromide, stir, and let stand at 28°C for 12 h. Then take the precipitate to obtain precipitate D.

[0096] (5) Wash the precipitate D three times with distilled water and centrifuge at 3000 rpm for 15 min. Take the precipitate and dry it at 50°C to constant weight to obtain cobalt phosphosilicate tungstate material.

[0097] The application of the cobalt phosphosilicate tungstate material prepared in this embodiment in the adsorption of Victoria Blue B includes the following steps:

[0098] Weigh 7 mg of cobalt phosphosilicate tungstate material and add it to 9 mL of Victoria Blue B solution with a concentration of 350 mg / L. Adjust the pH to 6 and stir at 35 °C for 70 min to adsorb Victoria Blue B.

[0099] Comparative Example 1

[0100] A cobalt phosphotungstenate material is prepared by the following steps:

[0101] (1) Weigh 1g of sodium phosphotungstenate and dissolve it in 30mL of deionized water to obtain solution A;

[0102] (2) Weigh 6g of cobalt nitrate hexahydrate and dissolve it in 30mL of deionized water to obtain solution B;

[0103] (3) Pour solution B into solution A, add 0.034 g of hexadecyltrimethylammonium bromide, stir, let stand at 28°C for 8 h, and then take the precipitate to obtain precipitate C;

[0104] (4) Wash the precipitate C three times with distilled water and centrifuge at 3000 rpm for 15 min. Take the precipitate and dry it at 50°C to constant weight to obtain cobalt phosphotungstate material.

[0105] The application of the cobalt phosphotungstenate material prepared in this comparative example in the adsorption of Victoria Blue B includes the following steps:

[0106] Weigh 5 mg of cobalt phosphotungstenate and add it to 9 mL of Victoria Blue B solution with a concentration of 200 mg / L. Adjust the pH to 7 and stir at 25 °C for 40 min to adsorb Victoria Blue B.

[0107] Comparative Example 2

[0108] A cobalt silicate material is prepared by the following steps:

[0109] (1) Weigh 5g of sodium silicate and dissolve it in 30mL of deionized water to obtain solution A;

[0110] (2) Weigh 6g of cobalt nitrate hexahydrate and dissolve it in 30mL of deionized water to obtain solution B;

[0111] (3) Pour solution B into solution A, add 0.034 g of hexadecyltrimethylammonium bromide, stir, let stand at 28°C for 8 h, and then take the precipitate to obtain precipitate C;

[0112] (4) Wash the precipitate C three times with distilled water and centrifuge at 3000 rpm for 15 min. Take the precipitate and dry it at 50°C to constant weight to obtain cobalt silicate material.

[0113] The application of the cobalt silicate material prepared in this comparative example in the adsorption of Victoria Blue B includes the following steps:

[0114] Weigh 5 mg of cobalt silicate material and add it to 9 mL of Victoria Blue B solution with a concentration of 200 mg / L. Adjust the pH to 7 and stir at 25 °C for 40 min to adsorb Victoria Blue B.

[0115] Comparative Example 3

[0116] The application of activated carbon in the adsorption of Victoria Blue B includes the following steps:

[0117] Weigh 5 mg of activated carbon and add it to 9 mL of a 200 mg / L Victoria Blue B solution. Adjust the pH to 7 and stir at 25 °C for 40 min to adsorb Victoria Blue B.

[0118] Experimental Example

[0119] The cobalt phosphosilicate, cobalt phosphotungstate, and cobalt silicate materials involved in this experimental example were prepared by the preparation methods in Example 1, Comparative Example 1, and Comparative Example 2, respectively.

[0120] 1. The morphology of cobalt phosphosilicate tungstate was characterized using a Sigma 300 scanning electron microscope (SEM); the structure of the cobalt phosphosilicate tungstate was characterized using a DX-2700 X-ray diffractometer (XRD); the results are as follows. Figures 1-4 As shown. From Figure 1 As can be seen, cobalt phosphosilicate tungstate material is composed of many stacked nanoparticles with large gaps between them and a loose, rough surface, providing more active sites for the adsorption of Victoria Blue B molecules, resulting in excellent adsorption performance; from Figure 2 It can be seen that cobalt phosphotungstenate has a more compact particle packing and a rougher surface, but its pores are fewer and smaller, thus its adsorption performance is not as good as that of cobalt phosphosilicate tungstenate; from Figure 3 As can be seen, after adsorbing Victoria Blue B, the cobalt phosphosilicate tungstate material exhibits a decrease in porosity and voids on its surface compared to before adsorption, indicating that the cobalt phosphosilicate tungstate material can effectively adsorb Victoria Blue B. From... Figure 4 As can be seen from the data, the XRD spectra of cobalt phosphotungstate, cobalt silicate, and cobalt phosphotungstate are basically the same. The cobalt phosphotungstate material shows a hump in the range of 15° to 40°, and the diffraction peak is wide and weak, indicating that the obtained cobalt phosphotungstate material is amorphous. In contrast to cobalt phosphotungstate and cobalt silicate, all three are amorphous.

[0121] 2. Fourier transform infrared spectroscopy (FTIR) was used to characterize the characteristic groups, structure, and chemical bonds of cobalt phosphotungstic acid material before and after adsorption of Victoria Blue B, sodium phosphotungstic acid, cobalt phosphotungstic acid material, and cobalt silicate material; the results are as follows: Figure 5 As shown in the FTIR spectra of cobalt phosphotungstenate and sodium phosphotungstenate, it can be seen that in the range of 1100–750 cm⁻¹... -1 The absorption peak at this location indicates the presence of [PW] with an α-Keggin structure. 12 O 40 ] 3- Anionic cobalt phosphosilicate materials do not possess an α-Keggin structure [PW 12 O 40 ] 3- Anions; the materials before and after adsorption of sodium phosphotungstate, cobalt phosphotungstate, and cobalt phosphosilicate were all at 1384 cm⁻¹. -1 There are relatively weak absorption peaks at [cm]. For the bending vibration peak belonging to OH, the characteristic stretching vibration peaks related to W=O and PO bonds are located at 952 and 1048 cm⁻¹, respectively. -1 Nearby; cobalt silicate material at 1048 cm -1 The absorption peak signal at 463 cm⁻¹ is the vibrational absorption peak of Co-O-Si. -1 The obvious peak at 435 cm⁻¹ belongs to the tensile vibration peak of Si-O; the peak at 435 cm⁻¹ is also observed in both the cobalt phosphosilicate tungstate material and the comparative material. -1 The band at 952 cm⁻¹ is attributed to the stretching vibration peak of Co-O; after adsorption of Victoria Blue B, the cobalt phosphosilicate material at 952 cm⁻¹... -1 The tensile vibration peak of W=O nearby is not obvious, which may be due to the structural change of cobalt phosphosilicate after the adsorption of Victoria Blue B.

[0122] 3. The speciation and chemical behavior of elements on the surface of cobalt phosphotungstenate before and after adsorption of Victoria Blue B were determined using an Escalab 250Xi X-ray photoelectron spectroscopy (XPS); the results are as follows: Figures 6-11 As shown. Figure 6 As shown, cobalt phosphosilicate tungstate materials contain P, Si, W, Co, and O elements. For example... Figure 7 As shown, the binding state of cobalt phosphosilicate tungstate material near 133.8 eV is P. 5+ The presence of PO-Si bonds may trigger the transfer of the P 2p component to 132.6 eV. The cobalt phosphotungstenate material exhibits a significant peak at 133.2 eV, confirming the presence of P. 5+ Because the P content in the adsorbed cobalt phosphosilicate tungstate material is relatively low, the XPS spectrum of P 2p does not show a significant peak. Figure 8 In the adsorbed cobalt phosphosilicate tungstate material, a distinct peak at 103.1 eV is attributed to Si-O-Si bonds, while the peak at 101.4 eV corresponds to a Si 2p satellite peak and is attributed to Si-OP bonds. The peak at 102.4 eV in the adsorbed cobalt phosphosilicate tungstate material represents Si-O bonds. Figure 9 In the study, the XPS spectra of W 4f for all W-containing materials can be fitted to four peaks, and the W 4f of the polyoxometalate units of cobalt phosphosilicate tungstate material is also shown to be four peaks. 7 / 2 and W 4f 5 / 2 The binding energies are located around 35.2 and 37.4 eV, respectively, with a difference of 2.2 eV, indicating the presence of W=O bonds, i.e., the presence of W bonds. 6+ W 4f of cobalt phosphotungstenate material 7 / 2 and W4f 5 / 2 The presence of two characteristic peaks at 34.8 and 37.0 eV respectively proves the existence of W. 6+ The XPS spectrum of W 4f in the adsorbed cobalt phosphosilicate tungstate material is essentially unchanged compared to that of the original cobalt phosphosilicate tungstate material, indicating that W exists in the +6 valence state in the adsorbed material. Figure 10 In the study, the XPS spectra of Co 2p in all Co-containing materials could be fitted to four peaks, and the Co 2p of cobalt phosphosilicate tungstate material showed the same pattern. 3 / 2 and Co 2p 1 / 2 It exhibits two characteristic peaks at 780.8 and 796.8 eV, respectively, and these peaks are attributed to Co. 2+ The satellite peaks at 786.3 and 802.4 eV further confirm the presence of Co. 2+ Co 2p in cobalt phosphotungstenate materials 3 / 2 and Co 2p 1 / 2 The presence of two characteristic peaks at 779.7 and 796.4 eV respectively proves the existence of Co. 2+The two broad peaks near 785.0 and 801.6 eV are satellite peaks, further confirming that Co... 2+ The presence of [something]; the binding energy of Co 2p in the adsorbed cobalt phosphosilicate tungstate material undergoes a negative shift compared to before adsorption, possibly due to structural changes following adsorption. For example... Figure 11 As shown, the XPS spectrum of the O1s of the cobalt phosphosilicate tungstate material can be fitted with three characteristic peaks: the peaks at 531 and 530 eV represent P=O and POP bonds, respectively; the characteristic peak at 532.7 eV indicates the presence of surface-adsorbed water molecules in the synthesized material; the O1s spectrum of the cobalt phosphosilicate tungstate material can be fitted with two peaks: the peak at 529.7 eV is attributed to lattice oxygen, while the binding peak at 531.1 eV is attributed to surface oxygen; the XPS spectrum of the O1s of the adsorbed cobalt phosphosilicate tungstate material has two fitted peaks: the binding peak at 530.9 eV indicates the presence of lattice oxygen bound to phosphorus and tungsten, while the peak at 532.2 eV can be attributed to surface-adsorbed H2O species. Analysis Figures 6-11 It can be seen that after the addition of Si, the binding energies of all elements in cobalt phosphosilicate tungstate shift towards higher energies. This is because the electron density of the corresponding elements decreases after silicon combines with oxygen, meaning that electrons flow from the silicon element to the surrounding other elements.

[0123] 4. The hydrophobicity-hydrophilicity of cobalt phosphosilicate tungstate material was evaluated.

[0124] (1) The surface properties of cobalt phosphosilicate tungstate material were studied using n-heptane and water vapor of different polarities. 300 mg of powdered adsorbent material was placed in a weighing bottle (25*25 mm), dried at 105 °C for 24 h, cooled in a desiccator, and then weighed accurately. In an atmosphere of saturated solvent vapor, 30 mL of solvent (water or n-heptane) was used to store the sample in an Erlenmeyer flask with a glass lid (29 / 32 frosted glass connector). The dry powder sample in the weighing bottle was placed in a position not in contact with the Erlenmeyer flask wall. After standing at 25 °C for 24 h, the weighing bottle containing the solid sample was removed from the Erlenmeyer flask, and the outside of the weighing bottle was wiped dry with lens paper. The amount of vapor adsorbed on the sample was obtained from the difference between the final mass and the initial mass of the solid sample, expressed in mg·g⁻¹. -1 The hydrophobicity ratio (HI) is expressed as the amount of n-heptane vapor adsorbed (mg·g). -1 The HI value is calculated by dividing the amount of n-heptane vapor adsorbed by the amount of water vapor adsorbed (mg·g). -1 Divide by the amount of water vapor adsorbed (mg·g) -1 The HI value was calculated using the formula . The HI value of 0.366 indicates that the synthesized cobalt phosphosilicate is a hydrophilic material (HI < 1.00).

[0125] (2) The contact angle of the cobalt phosphosilicate tungstate material was measured using a JC 2000C contact angle measuring instrument. The contact angle of the cobalt phosphosilicate tungstate material was 63°. Figure 12 As shown, this further demonstrates that the prepared cobalt phosphosilicate tungstate material exhibits hydrophilicity.

[0126] 5. The adsorption rate of Victoria Blue B on the material was determined and calculated according to the following method. When adsorption reached equilibrium, the material was centrifuged at 3500 rpm for 15 min. The absorbance of the supernatant was measured at a wavelength of 615 nm. The adsorption rate was calculated based on the change in solution concentration before and after adsorption, and the adsorption amount was also calculated. The calculation formula is as follows:

[0127]

[0128]

[0129] In Equation 1, C0 is the initial concentration of Victoria Blue B; in Equation 2, q e (mg·g -1 ) represents the adsorption capacity, C0 and C e (mg·L -1 V(L) represents the initial concentration of Victoria Blue B and the dye concentration at adsorption equilibrium, respectively. V(L) is the volume of Victoria Blue B, and m(g) is the mass of cobalt phosphosilicate tungstate material.

[0130] The adsorption rates of Victoria Blue B on the cobalt phosphosilicate tungstate material prepared in Example 1 and the activated carbon in Comparative Example 4 were measured. The results showed that the adsorption capacity of Victoria Blue B on the cobalt phosphosilicate tungstate material prepared in Example 1 was 350 mg·g. -l The removal rate was 97.5%; while in Comparative Example 4, the removal rate of activated carbon for Victoria Blue B was 60.3%.

[0131] 6. Adsorption experiments were conducted using NaCl and NaNO3 to simulate salts in wastewater, investigating the effect of ionic strength in the solution on the adsorption of Victoria Blue B by cobalt phosphosilicate tungstate material. The results are as follows: Figures 13-14 As shown. By Figure 13 It can be seen that the adsorption capacity of cobalt phosphosilicate tungstate for Victoria Blue B initially increases and then reaches equilibrium with increasing NaCl and NaNO3 concentrations; furthermore, at corresponding concentrations, the adsorption capacity of NaNO3 is higher than that of NaCl, because Cl... - and NO 3- The interaction with Victoria Blue B leads to a decrease in the absorbance of Victoria Blue B, thereby increasing its adsorption capacity. Figure 14 It can be seen that NO 3- Compared to Cl - Its large size and significant interaction with Victoria Blue B, NO 3-It will promote the aggregation of Victoria Blue B, forming flocculent precipitates, which reduces its absorbance. Therefore, the adsorption capacity of cobalt phosphosilicate tungstate material for Victoria Blue B is higher in the NaNO3 environment than in the NaCl environment.

[0132] 7. To explain the adsorption behavior of cobalt phosphosilicate tungstate materials, pseudo-first-order, pseudo-second-order, and intraparticle diffusion adsorption kinetic models were used for the study.

[0133] The quasi-first-order nonlinear equation is:

[0134]

[0135] In Equation 3, q e (mg·g -1 ) represents the equilibrium adsorption amount, q t (mg·g -1 ) represents the amount of adsorption at time t, k1(min) -1 ) is the rate constant of the pseudo-first-order adsorption equation, t(min -1 () represents the adsorption time.

[0136] Quasi-second-order nonlinear equations:

[0137]

[0138] In Equation 4, k2(g·(mg) -1 ·min -1 ) -1 ) is the rate constant of the pseudo-second-order adsorption equation.

[0139] The intraparticle diffusion equation is:

[0140] q t =k i t 1 / 2 +c (Equation 5)

[0141] In Equation 5, k i (mg·g -1 ·min -1 / 2 ) is the intraparticle diffusion rate constant, c(mg·g) -1 ) is a constant representing the boundary layer thickness.

[0142] The fitting curves of the quasi-first-order rate equation and the quasi-second-order rate equation are as follows: Figure 15 and 16 kinetic parameter q e k1, k2 and correlation coefficient R 2 The results, obtained from the nonlinear regression equation, are listed in Table 1. The Ri values ​​of the pseudo-first-order kinetic model at different concentrations are... 2 R is smaller than that of the quasi-second-order dynamic model 2 (R 2The equilibrium adsorption capacity was ≥0.96, and the fitted equilibrium adsorption capacity was consistent with the experimentally measured equilibrium adsorption capacity, indicating that the pseudo-second-order kinetic model is more suitable for describing the adsorption behavior of cobalt phosphosilicate tungstate on Victoria Blue B; indicating that the adsorption of Victoria Blue B by cobalt phosphosilicate tungstate is mainly chemical adsorption and supplemented by physical adsorption.

[0143] Figure 17 Tables 1 and 2 show the fitted curves and corresponding parameters of the intraparticle diffusion equation, respectively. Based on the intraparticle diffusion equation and corresponding parameters, q... t For t 1 / 2 The curves are not straight lines and do not pass through the origin, so intraparticle diffusion is not the only rate-controlling step; for example... Figure 17 Throughout the entire time range, these curves are not linear and can be divided into two linear segments. That is, the adsorption of Victoria Blue B dye by cobalt phosphosilicate tungstate material involves two processes, and intraparticle diffusion is not the only rate-determining step.

[0144] Table 1

[0145]

[0146] Table 2

[0147]

[0148] 8. Adsorption isotherms are one of the important parameters describing the adsorption behavior of an adsorption system and are of great significance for understanding adsorption behavior. This study mainly uses three adsorption isotherm models—Langmuir, Freundlich, and Temkin—to analyze the data on the adsorption of Victoria Blue B dye onto cobalt phosphosilicate tungstate materials. Figures 18-20 As shown, the isothermal equation is as follows:

[0149] The Langmuir equation is:

[0150]

[0151] The Freundlich equation is:

[0152]

[0153] The Temkin equation is:

[0154] q e =A ln C e +B (Equation 8)

[0155] In equations (6), (7) and (8), C e (mg·L -1 q represents the equilibrium concentration of Victoria Blue B in the solution. e (mg·g -1K represents the equilibrium adsorption amount. L (L·mg -1 ) represents the Langmuir adsorption constant, q m (mg·g -1 K represents the maximum adsorption capacity of a single layer. f (mg·g -1 (mg·L -1 ) -1 / n ) and n are Freundlich isotherm constants, describing the multilayer adsorption capacity and strength, respectively, while A and B are constants in the Temkin equation. Experimental data from three adsorption isotherm models—Langmuir, Freundlich, and Temkin—were fitted; the fitting results and relevant parameters are shown in Table 3. The correlation coefficient RFreundlich isotherm model is shown in Table 3. 2 The value of n is closer to 1, indicating that the Freundlich isothermal adsorption model can describe the adsorption process well; and the value of n is between 2.0 and 3.0, that is, 1 / n is less than 1, indicating that the adsorption is good in the temperature range of 20 to 35℃ and is a heterogeneous multilayer adsorption.

[0156] Table 3

[0157]

[0158]

[0159] 9. The thermodynamic behavior of cobalt phosphosilicate tungstate material adsorbing Victoria Blue B can be analyzed by the Gibbs free energy change (ΔG). 0 ), enthalpy change (ΔH) 0 and entropy change (ΔS) 0 The evaluation is based on three types of thermodynamic parameters. These parameters can be calculated using the following equations:

[0160]

[0161] ΔG 0 =-RT ln K 0 (Equation 10)

[0162] ΔG 0 =ΔH 0 -TΔS 0 (Equation 11)

[0163]

[0164] In Equation 9, K 0 (L·g (1-1 / n) K is the thermodynamic equilibrium constant. f (mg·g -1 (mg·L -1 ) -1 / n) is the Freundlich equilibrium constant, M (g·mol) -1 ( ) represents the molar mass of Victoria Blue B, C 0 The standard concentration of Victoria Blue B (1 mol·L⁻¹) -1 ), where γ is the activity coefficient (dimensionless) of Victoria Blue B, and its value is set to 1; in Equation 10, K 0 (L·g (1-1 / n) R is the thermodynamic equilibrium constant, which is 8.314 J·mol⁻¹. -1 ·K -1 () is the gas constant, and T(K) is the thermodynamic temperature; in Equation 11, T(K) is the thermodynamic temperature; in Equation 12, K 0 (L·g (1-1 / n) R is the thermodynamic equilibrium constant, T(K) is the thermodynamic temperature, and R(8.314 J·mol⁻¹) is the thermodynamic equilibrium constant. -1 ·K -1 ) is the gas constant.

[0165] Thermodynamic linear fitting such as Figure 21 ΔG 0 ΔH 0 and ΔS 0 The values ​​are shown in Table 4; experimental data obtained by fitting the Van't Hoff linear equation at 20℃, 25℃, and 30℃, ΔG 0 The values ​​are -34.42, -35.78, and -37.01 kJ·mol⁻¹, respectively. -1 This indicates that the adsorption of Victoria Blue B by cobalt phosphosilicate tungstate material is a feasible and spontaneous process; ΔH 0 It is 41.4 kJ·mol -1 This indicates that the adsorption of Victoria Blue B by cobalt phosphosilicate tungstate material is an endothermic process; ΔS 0 A positive value means that the degree of freedom of the solid-liquid interface in the adsorption system increases, while the degree of order decreases.

[0166] Table 4

[0167]

[0168] 10. The regeneration and recycling of the adsorbent are important standards for practical applications. The adsorption cycle of the material is carried out according to the following method. After the cobalt phosphosilicate tungstate material adsorbs Victoria Blue B, it is centrifuged, the absorbance is measured, and the supernatant is aspirated using a disposable syringe. Then, 3 mL of a 0.5 mol·L⁻¹ solution is added. -1 The sodium hydroxide solution was sonicated for 10 minutes, and the above steps were repeated 3 times. The solution was then washed with ethanol until it was nearly colorless after centrifugation. Finally, the precipitate was dried in a 50°C oven for subsequent adsorption experiments. This process was repeated 5 times. The results are as follows: Figure 22As shown, the removal rate of Victoria Blue B by the cobalt phosphosilicate tungstate material was 97.5%. After 5 cycles, the removal rate of Victoria Blue B by the cobalt phosphosilicate tungstate material was 86.7%. The removal rate after the 5th cycle decreased by 10.8% compared with the removal rate after the 1st cycle, indicating that the synthesized cobalt phosphosilicate tungstate material has a certain degree of renewability. The reason for the decrease in adsorption efficiency may be the loss of adsorbent during the cycle and the difficulty of desorption during the chemical adsorption process.

[0169] The present invention has been described according to the above embodiments. It should be understood that the above embodiments do not limit the present invention in any way. All technical solutions obtained by equivalent substitution or equivalent transformation fall within the scope of the present invention.

Claims

1. A method for preparing cobalt phosphosilicate tungstate material for adsorbing Victoria Blue B, characterized in that, Includes the following steps: (1) Dissolve phosphotungstate in water to obtain solution A; (2) Dissolve silicate in solution A to obtain solution B; (3) Dissolve the soluble cobalt salt in water to obtain solution C; (4) Pour solution C into solution B, add phase transfer catalyst, and let stand at 25~30 ℃ for 2~12 h. Then take the precipitate to obtain precipitate D. (5) The precipitate D was dried to constant weight to obtain cobalt phosphosilicate tungstate material; The phosphotungsten is sodium phosphotungsten; the silicate is sodium silicate; the soluble cobalt salt is cobalt nitrate hexahydrate; the phase transfer catalyst in step (4) is hexadecyltrimethylammonium bromide; the standing temperature is 28 ℃ and the standing time is 8 h; the mass ratio of sodium phosphotungsten to phase transfer catalyst is 1:(0.03~0.04); the mass ratio of sodium phosphotungsten, cobalt nitrate hexahydrate and sodium silicate is 1:(2~8):(2~8).

2. Cobalt phosphosilicate tungstate material prepared by the preparation method described in claim 1.

3. The application of the cobalt phosphosilicate tungstate material according to claim 2 in the adsorption of Victoria Blue B.

4. The application as described in claim 3, characterized in that, Includes the following steps: Cobalt phosphosilicate tungstate material was added to a Victoria Blue B solution with a concentration of 150~350 mg / L, the pH was adjusted to 6~8, and the mixture was stirred at 20~35 ℃ for 30~70 min to adsorb Victoria Blue B.

5. The application as described in claim 4, characterized in that: The ratio of the cobalt phosphosilicate tungstate material to the Victoria Blue B solution is 3~7 mg:8~10 mL.

6. The application as described in claim 4, characterized in that: The pH value is 7; the stirring temperature is 25 °C; and the stirring time is 40 min.

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