Transition metal phosphate composite material as well as preparation method and application thereof

Abstract

The invention discloses a transition metal phosphate composite material as well as a preparation method and application thereof. The preparation method comprises the following steps: dispersing an amyloid protein fiber suspension into a monopotassium phosphate solution, adding a transition metal salt solution, and reacting to obtain the transition metal phosphate composite material. The transition metal phosphate composite material with the three-dimensional network porous structure is prepared through liquid-phase in-situ growth, and the composite material can initiate interface electronic structure reconstruction of complex-state heavy metal in water and drive electron transfer in complex-state heavy metal molecules through advanced oxidation reaction; and meanwhile, the released heavy metal ions can be separated and removed in situ through the synergistic effect of electrostatic attraction, surface coordination and interface electron transfer.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental protection, and in particular relates to a transition metal phosphate composite material and a preparation method and application thereof. Background Art

[0002] Heavy metal-related industries use a large amount of organic chelating agents in the production process, causing the heavy metal pollution in their wastewater to show organic-inorganic composite pollution characteristics. Unlike free heavy metals, the complexed heavy metal pollution formed by organic ligands and heavy metals is difficult to be effectively removed by traditional chemical precipitation, adsorption and other methods. At present, the common treatment method for heavy metal complexes in water is the advanced oxidation-chemical precipitation combined process, that is, first using advanced oxidation technology to destroy the organic ligands of the heavy metal complex, releasing heavy metal ions, and then removing the released heavy metal ions by chemical precipitation. This treatment method is not only complex in process, but also the oxidation and decomposition process of complexed heavy metals in water by traditional advanced oxidation technology is easily affected by coexisting impurities, resulting in poor decomposition selectivity and low heavy metal removal efficiency. Summary of the Invention

[0003] To address the above issues, the present invention provides a transition metal phosphate composite material, its preparation method, and its application. The present invention prepares a transition metal phosphate composite material with a three-dimensional network porous structure through in-situ liquid phase growth. This composite material can not only trigger the reconstruction of the interfacial electronic structure of complexed heavy metals in water, but also drive intramolecular electron transfer of the complexed heavy metals through advanced oxidation reactions, achieving efficient targeted decomposition of the complexed heavy metals. Furthermore, it can achieve in-situ separation and removal of released heavy metal ions through the synergistic effects of electrostatic attraction, surface coordination, and interfacial electron transfer.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] In one aspect, the present invention provides a method for preparing a transition metal phosphate composite material, comprising the following steps:

[0006] An amyloid protein fiber suspension is dispersed in a potassium dihydrogen phosphate solution, and a transition metal salt solution is added to react to obtain the transition metal phosphate composite material.

[0007] As a preferred embodiment, the method for preparing the amyloid fiber suspension comprises the following steps:

[0008] Disperse β-lactoglobulin amyloid fiber powder in water, adjust the pH to 2.0-3.0 with hydrochloric acid, and stir at 70-120° C. for 5-10 hours.

[0009] As a preferred embodiment, the transition metal salt is selected from at least one of copper salt, iron salt and cobalt salt; the copper salt is Cu 2+Salt; the iron salt is Fe 2+ Salt; the Co salt is Co 2+ Salt.

[0010] As a preferred embodiment, the reaction time is 2 to 6 hours.

[0011] As a preferred embodiment, the reaction is carried out in an inert atmosphere.

[0012] As a preferred embodiment, the acidity or alkalinity of the reaction system before adding the transition metal salt solution is adjusted to neutral or alkaline; and the pH of the reaction system after adding the transition metal salt solution is adjusted to 7-10.

[0013] As a preferred embodiment, the mass ratio of amyloid fibers to potassium dihydrogen phosphate in the amyloid fiber suspension is 1:1-20.

[0014] As a preferred embodiment, the molar ratio of the potassium dihydrogen phosphate to the transition metal contained in the transition metal salt is 1 to 25:1.

[0015] In certain specific embodiments, the reaction further comprises post-processing of centrifugation, washing, and vacuum freeze-drying.

[0016] In another aspect, the present invention provides a transition metal phosphate composite material obtained by the above preparation method.

[0017] In another aspect, the present invention provides use of the above-mentioned transition metal phosphate composite material in treating heavy metal wastewater, complexed heavy metal wastewater or organic complexing agent wastewater.

[0018] Preferably, the heavy metals include Ni, Pb and Cu.

[0019] Preferably, the organic complexing agent is EDTA.

[0020] Preferably, the complexed heavy metals include EDTA-Ni, EDTA-Pb and EDTA-Cu.

[0021] In the technical solution of the present invention, the transition metal phosphate composite material can remove complexed heavy metals in water.

[0022] In certain specific embodiments, the transition metal phosphate composite material and the oxidant are added to the complexed heavy metal wastewater and subjected to an oscillation reaction treatment for 2 to 6 hours. By destroying the coordination structure between the complexed heavy metal and the organic ligand, the heavy metal ions are released, and the free heavy metal ions are reduced, adsorbed and separated in situ.

[0023] In certain specific embodiments, during the oscillation reaction, the pH of the system is 3.0-10.0.

[0024] In certain specific embodiments, the amount of the transition metal phosphate composite material is 0.1-1.0 g / L.

[0025] In certain specific embodiments, the concentration of the complexed heavy metal is 0.1-1.0 mM.

[0026] In certain specific embodiments, the amount of the oxidant is 0.1-25 mM.

[0027] The present invention has the following advantages:

[0028] (1) The present invention prepares a transition metal phosphate composite material with a three-dimensional network porous structure through in situ growth in a liquid phase, wherein the amyloid protein fiber serves as the skeleton of the composite material, which can not only form a pre-enrichment effect on the complexed heavy metals in water, but also enhance the surface electron density of the transition metal phosphate microcrystals grown thereon, thereby promoting the interfacial electron transfer process between the composite material, the complexed heavy metals and the oxidant, and can also couple the advanced oxidation process to achieve efficient targeted decomposition of the complexed heavy metals.

[0029] (2) The three-dimensional network porous structure of the transition metal phosphate composite material prepared by the present invention gives it a larger specific surface area and can expose more active sites. The hydroxyl and amine groups on the surface of the composite material can not only capture the heavy metal ions released after the network is broken, but also directly enhance the stability of the heavy metals adsorbed on the surface of the material through electron transfer, thereby realizing the simultaneous separation and removal of heavy metal ions.

[0030] (3) The transition metal phosphate composite material prepared by the present invention can efficiently purify a variety of complex heavy metals in water within a wide pH range (3.0-10.0), including EDTA-Ni (90%-98%), EDTA-Cu (95%-99%) and EDTA-Pb (90%-100%). BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a TEM image of the transition metal phosphate composite material 3D-Net@CuP prepared in Example 1 of the present invention.

[0032] Figure 2 This is a TEM image of the transition metal phosphate composite material 3D-Net@FeP prepared in Example 1 of the present invention.

[0033] Figure 3 This is a TEM image of the transition metal phosphate composite material 3D-Net@CoP prepared in Example 1 of the present invention.

[0034] Figure 43D-Net@CuP is an XRD pattern of the transition metal phosphate composite material prepared in Example 1 of the present invention.

[0035] Figure 5 3D-Net@FeP is an XRD pattern of the transition metal phosphate composite material prepared in Example 1 of the present invention.

[0036] Figure 6 3D-Net@CoP is an XRD pattern of the transition metal phosphate composite material prepared in Example 1 of the present invention.

[0037] Figure 7 This is a comparison chart of the selective removal effects of EDTA-Pb by the 3D-Net@CuP-CaO2 and Fenton-alkali treatment combined processes in Example 1 of the present invention.

[0038] Figure 8 This is a comparison chart of the selective removal effects of EDTA-Cu by the 3D-Net@FeP-PDS and Fenton-alkali treatment combined processes in Example 2 of the present invention.

[0039] Figure 9 This is a comparison chart of the selective removal effects of EDTA-Ni by the 3D-Net@CoP-PMS and Fenton-alkali treatment combined processes in Example 3 of the present invention. DETAILED DESCRIPTION

[0040] The following embodiments are merely some of the embodiments of the present invention, rather than all of them. Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by those skilled in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0041] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0042] Example 1:

[0043] This embodiment provides a transition metal phosphate composite material 3D-Net@CuP, and the preparation process is as follows:

[0044] 5 mL of amyloid fiber suspension was dispersed in 145 mL of 0.08 M potassium dihydrogen phosphate solution; the pH was adjusted to 7.0 with 5% sodium hydroxide solution; 50 mL of 0.01 M copper chloride solution was added dropwise at a rate of 2 mL / min; the reaction was magnetically stirred under argon protection for 2 h; the resulting material was centrifuged and repeatedly washed with ultrapure water to remove impurities, and then vacuum-dried to obtain the transition metal phosphate composite material 3D-Net@CuP.

[0045] In this embodiment, the preparation process of the amyloid fiber suspension is as follows:

[0046] 3 g of β-lactoglobulin amyloid fiber powder was dispersed in 100 mL of ultrapure water, and the pH was adjusted to 3.0 with hydrochloric acid. The suspension was then placed in a 100° C. water bath and magnetically stirred for 6 h to obtain an amyloid fiber suspension with a concentration of approximately 3%.

[0047] In this example, 3D-Net@CuP was used to treat wastewater containing complexed heavy metals. A co-catalytic decomposition-separation and removal system 3D-Net@CuP-CaO2 was constructed by combining 3D-Net@CuP with heavy metal complexes and calcium peroxide (oxidant). The specific method was as follows: a 250 mL beaker was used as a reactor, and simulated wastewater with a concentration of 0.1 mM EDTA-Ni, EDTA-Cu, and EDTA-Pb was prepared. 200 mL of each was added to the corresponding reactor; then 0.02 g of 3D-Net@CuP and 0.02 mmol of EDTA-Cu were added to each reactor. CaO2; the reactor was placed in a water pot at 25°C and magnetically stirred at 200 rpm. After 2 hours of reaction, the complexation removal efficiency of EDTA-Ni, EDTA-Cu and EDTA-Pb under different pH reaction conditions in the corresponding systems was calculated respectively. The results are shown in Table 1: when only 3D-Net@CuP was added to the system and no calcium peroxide was added, the removal rate of complexed heavy metals in the system was less than 12%, indicating that 3D-Net@CuP could not remove complexed heavy metals in water by adsorption; after adding CaO2 to the system, the removal rate of heavy metal pollution in the system increased significantly, indicating that the 3D-Net@CuP-CaO2 system effectively triggered the oxidative complexation of complexed heavy metals and the in situ removal of heavy metal ions after complexation.

[0048] This example also tests the removal effect of the traditional two-stage Fenton-alkali treatment combined process on EDTA-Ni, EDTA-Cu and EDTA-Pb. The specific process parameters of the two-stage Fenton-alkali treatment combined process are: Fenton stage: 0.05 MFe 2+-0.05M H2O2, reaction for 2h; alkaline treatment stage: 1% sodium hydroxide to adjust the pH to 11.0, precipitation for 2h. The test results are shown in Table 1: The 3D-Net@CuP-CaO2 in this embodiment has a wider pH application range than the Fenton-alkaline treatment combined process. Within pH 3.0-10.0, the in-situ complex removal efficiency of EDTA-Ni, EDTA-Cu, and EDTA-Pb is higher than 90%. The Fenton-alkaline treatment combined process can only oxidize and decompose the three complexed heavy metals in water when the Fenton system pH is 3.0. However, its highest complex removal efficiency for EDTA-Ni, EDTA-Cu, and EDTA-Pb is 60%, 82%, and 77%, respectively, which is much lower than that of the 3D-Net@CuP-CaO2 system.

[0049] In addition, compared with the two-stage Fenton-alkali treatment process, the 3D-Net@CuP-CaO2 system also showed excellent selectivity for the removal of complexed heavy metals, such as Figure 7 As shown, taking the removal of EDTA-Pb as an example, when 10 mM chloride ions, nitrate ions, sulfate ions and 10 mg / L humus are also present in the system, the EDTA-Pb removal efficiency in the 3D-Net@CuP-CaO2 system can still reach 91%, while the removal rate of the Fenton-alkali treatment combined process system is only 36%.

[0050] Table 1

[0051]

[0052] Example 2:

[0053] This embodiment provides a transition metal phosphate composite material 3D-Net@FeP, the preparation process of which is as follows:

[0054] 15 mL of amyloid fiber suspension was dispersed in 135 mL of 0.05 M potassium dihydrogen phosphate solution; the pH was adjusted to 7.0 with 5% sodium hydroxide solution; 50 mL of 0.05 M ferrous chloride solution was added dropwise at a rate of 2 mL / min; the reaction was magnetically stirred under argon protection for 4 hours; the resulting material was centrifuged and repeatedly washed with ultrapure water to remove impurities, and then vacuum-dried to obtain the transition metal phosphate composite material 3D-Net@FeP.

[0055] In this example, the preparation process of the amyloid fiber suspension is the same as that in Example 1.

[0056] In this example, 3D-Net@FeP was used to treat wastewater containing complexed heavy metals. A co-catalytic decomposition-separation removal system 3D-Net@FeP-PDS was constructed by combining 3D-Net@FeP with heavy metal complexes and peroxydisulfate (PDS). The specific method was as follows: a 250 mL beaker was used as a reactor, and simulated wastewater with a concentration of 0.5 mM EDTA-Ni, EDTA-Cu, and EDTA-Pb was prepared. 200 mL of each was added to the corresponding reactor, and then 0.1 g 3D-Net@FeP and 1.0 mmol PDS were added to each reactor. PDS; the reactor was placed in a water pot at 25°C and magnetically stirred at 200 rpm. After 4 hours of reaction, the complexation removal efficiency of EDTA-Ni, EDTA-Cu and EDTA-Pb under different pH reaction conditions in the corresponding systems was calculated. The results are shown in Table 2: When only 3D-Net@FeP was added to the system without peroxydisulfate, the removal rate of complexed heavy metals in the system was less than 9%, indicating that 3D-Net@FeP could not remove complexed heavy metals in water by adsorption; when PDS was added to the system, the removal rate of heavy metal pollution in the system increased significantly, indicating that the 3D-Net@FeP-PDS system effectively triggered the oxidative complexation of complexed heavy metals and the in situ removal of heavy metal ions after complexation.

[0057] This example also tests the removal effect of the traditional two-stage Fenton-alkali treatment combined process on EDTA-Ni, EDTA-Cu and EDTA-Pb. The specific process parameters of the two-stage Fenton-alkali treatment combined process are: Fenton stage: 0.05 MFe 2+ -0.05M H2O2, reaction for 2 hours; alkaline treatment stage: 1% sodium hydroxide to adjust the pH to 11.0, precipitation for 2 hours. Test results are shown in Table 1: The 3D-Net@FeP-PDS in this example has a wider pH range of application compared to the Fenton-alkaline treatment combined process. Within pH 3.0-10.0, the in-situ complex removal efficiency of EDTA-Ni, EDTA-Cu, and EDTA-Pb is higher than 92%. The combined treatment process can only oxidize and decompose the three complexed heavy metals in water when the Fenton system pH is 3.0. However, its highest complex removal efficiency for EDTA-Ni, EDTA-Cu, and EDTA-Pb is 42%, 50%, and 57%, respectively, which is much lower than that of the 3D-Net@FeP-PDS system.

[0058] In addition, compared with the two-stage Fenton-alkali treatment process, the 3D-Net@FeP-PDS system also showed excellent selectivity for the removal of complexed heavy metals, such as Figure 8As shown, taking the removal of EDTA-Cu as an example, when 10 mM chloride ions, nitrate ions, sulfate ions and 10 mg / L humus are also present in the system, the EDTA-Cu removal efficiency in the 3D-Net@FeP-PDS system can still reach 97%, while the removal rate of the Fenton-alkali treatment combined process system is only 29%.

[0059] Table 2

[0060]

[0061] Example 3:

[0062] This embodiment provides a transition metal phosphate composite material 3D-Net@CoP, the preparation process of which is as follows:

[0063] 25 mL of amyloid fiber suspension was dispersed in 125 mL of 0.05 M potassium dihydrogen phosphate solution; the pH was adjusted to 7.0 with 5% sodium hydroxide solution; 50 mL of 0.10 M cobaltous chloride solution was added dropwise at a rate of 2 mL / min; the reaction was magnetically stirred under argon protection for 6 hours; the resulting material was centrifuged, repeatedly washed with ultrapure water to remove impurities, and then vacuum-freezed to obtain the transition metal phosphate composite material 3D-Net@CoP.

[0064] In this example, the preparation process of the amyloid fiber suspension is the same as that in Example 1.

[0065] In this example, 3D-Net@CoP was used to treat wastewater containing complexed heavy metals. A co-catalytic decomposition-separation and removal system 3D-Net@CoP-PMS was constructed with 3D-Net@CoP, heavy metal complexes, and peroxymonosulfate (PMS). The specific method was as follows: a 250 mL beaker was used as a reactor, and simulated wastewater with a concentration of 1.0 mM EDTA-Ni, EDTA-Cu, and EDTA-Pb was prepared, and 200 mL of each was added to the corresponding reactor; then 0.2 g 3D-Net@CoP and 5.0 mmol PMS were added to each reactor. PMS; the reactor was placed in a water pot at 25°C and magnetically stirred at 200 rpm. After 6 hours of reaction, the complexation removal efficiency of EDTA-Ni, EDTA-Cu and EDTA-Pb under different pH reaction conditions in the corresponding systems was calculated. The results are shown in Table 3: When only 3D-Net@CoP was added to the system without peroxymonosulfate, the removal rate of complexed heavy metals in the system was less than 12%, indicating that 3D-Net@CoP could not remove complexed heavy metals in water by adsorption; when PMS was added to the system, the removal rate of heavy metal pollution in the system increased significantly, indicating that the 3D-Net@CoP-PMS system effectively triggered the oxidation and complexation of complexed heavy metals and the in situ removal of heavy metal ions.

[0066] This example also tests the removal effect of the traditional two-stage Fenton-alkali treatment combined process on EDTA-Ni, EDTA-Cu and EDTA-Pb. The specific process parameters of the two-stage Fenton-alkali treatment combined process are: Fenton stage: 0.05 MFe 2+ -0.05M H2O2, reaction for 2 hours; alkaline treatment stage: 1% sodium hydroxide to adjust the pH to 11.0, precipitation for 2 hours. Test results are shown in Table 1: The 3D-Net@CoP-PMS in this example has a wider pH range of application compared to the Fenton-alkaline treatment combined process. Within pH 3.0-10.0, the in-situ complex removal efficiency of EDTA-Ni, EDTA-Cu, and EDTA-Pb is higher than 90%. The combined treatment process can only oxidize and decompose the three complexed heavy metals in water when the Fenton system pH is 3.0. However, its maximum complex removal efficiency for EDTA-Ni, EDTA-Cu, and EDTA-Pb is 23%, 65%, and 33%, respectively, which is much lower than that of the 3D-Net@CoP-PMS system.

[0067] In addition, compared with the two-stage Fenton-alkali treatment process, the 3D-Net@FeP-PMS system also showed excellent selectivity for the removal of complexed heavy metals, such as Figure 9 As shown, taking the removal of EDTA-Ni as an example, when 10 mM chloride ions, nitrate ions, sulfate ions and 10 mg / L humus are also present in the system, the EDTA-Ni removal efficiency in the 3D-Net@CoP-PMS system can still reach 84%, while the removal rate of the Fenton-alkali treatment combined process system is only 12%.

[0068] Table 3

[0069]

[0070]

[0071] Figure 1-3 Shown are TEM images of the transition metal phosphate composite materials prepared in Examples 1-3 of the present invention, respectively. It can be seen from the figures that the transition metal phosphate grains grow evenly on the protein amyloid fiber skeleton, and a large number of cross-linked protein amyloid fibers and transition metal phosphate grains together form a three-dimensional porous network structure of the composite material.

[0072] Figure 4-6 Shown are the XRD patterns of the transition metal phosphate composite materials prepared in Examples 1-3 of the present invention, respectively; the XRD patterns confirm that the protein amyloid fiber-loaded transition metal phosphate composite materials were successfully prepared by liquid phase in situ co-precipitation.

[0073] In summary, the transition metal phosphate composite material prepared by the present invention can achieve efficient complex breaking and simultaneous removal of various heavy metal complexes in water.

[0074] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a transition metal phosphate composite material, characterized in that: The following steps are involved: An amyloid protein fiber suspension is dispersed in a potassium dihydrogen phosphate solution, and a transition metal salt solution is added to react to obtain the transition metal phosphate composite material.

2. The preparation method according to claim 1, characterized in that The preparation method of the amyloid fiber suspension comprises the following steps: Disperse β-lactoglobulin amyloid fiber powder in water, adjust the pH to 2.0-3.0 with hydrochloric acid, and stir at 70-120° C. for 5-10 hours.

3. The preparation method according to claim 1, characterized in that The transition metal salt is selected from at least one of copper salt, iron salt and cobalt salt; the copper salt is Cu 2+ Salt; the iron salt is Fe 2+ Salt; the Co salt is Co 2+ Salt.

4. The preparation method according to claim 1, characterized in that The reaction time is 2 to 6 hours; and / or, the reaction is carried out in an inert atmosphere; And / or, the acidity or alkalinity of the reaction system before adding the transition metal salt solution is adjusted to neutral or alkaline; and the pH of the reaction system after adding the transition metal salt solution is adjusted to 7-10.

5. The preparation method according to claim 1, characterized in that The mass ratio of amyloid fiber to potassium dihydrogen phosphate in the amyloid fiber suspension is 1:1 to 20; And / or, the molar ratio of the potassium dihydrogen phosphate to the transition metal contained in the transition metal salt is 1 to 25:

1.

6. The transition metal phosphate composite material obtained by the preparation method according to any one of claims 1 to 5.

7. Use of the transition metal phosphate composite material according to claim 6 in treating heavy metal wastewater, complexed heavy metal wastewater or organic complexing agent wastewater.

8. The use according to claim 7, characterized in that The heavy metals include Ni, Pb and Cu; And / or, the organic complexing agent is EDTA; And / or, the complexed heavy metals include EDTA-Ni, EDTA-Pb and EDTA-Cu.

9. The use according to claim 7, characterized in that The transition metal phosphate composite material and the oxidant are added into the complexed heavy metal wastewater and subjected to oscillation reaction for 2 to 6 hours.

10. The use according to claim 9, characterized in that During the oscillation reaction, the pH of the system is 3.0 to 10.0; and / or, the amount of the transition metal phosphate composite material is 0.1 to 1.0 g / L; and / or, the concentration of the complexed heavy metal is 0.1 to 1.0 mM; And / or, the amount of the oxidant is 0.1-25 mM.

Images