A multi-purpose water treatment agent, preparation method and application

Abstract

The invention belongs to the technical field of polymer compounds and discloses a multi-purpose water treatment agent, a preparation method and an application thereof. 12 H8N2O4, Na2SiO3·9H2O, Na2MoO4·2H2O and 10 mL of pure water are mixed and stirred at room temperature for 30 minutes; nitric acid reagent and potassium hydroxide reagent are used to adjust the pH to 3.35, and after sufficient reaction, they are added into a stainless steel reactor with a polytetrafluoroethylene liner and sealed; after the reaction inside the reactor is completed, it is cooled to room temperature; the product in the reactor is washed with pure water to obtain light yellow transparent block crystals, which are filtered and placed in the air to dry naturally. The present invention adopts a simple preparation process, cheap and easily available synthetic raw materials, and mild reaction conditions to synthesize a multi-purpose water treatment agent, which can not only efficiently remove organic dye pollutants and nitrite ions, but also has fluorescence properties and electrochemical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer compounds, and in particular relates to a multi-purpose water treatment agent, a preparation method and application thereof. Background Art

[0002] At present, polyoxometalates, referred to as polyoxometalates (POM), are a kind of multiple metal oxygen polyhedra connected by oxygen from pre-transition metals (V, Mo, W, Nb, Ta). These polyhedra form a special type of polynuclear metal oxides by connecting with common edges, planes or angles. Because polyoxometalates have a unique structure: they have a certain cluster structure, the polyoxometalate anion cluster is large in size, and the number of oxygen atoms is large, which makes the polyoxometalate compounds have excellent redox properties and high charge density. The polyoxometalate anions can also be used as inorganic ligands or guest molecules to combine with metal-organic compounds to form inorganic-organic hybrid materials containing polyoxometalates. Therefore, polyoxometalates have potential applications in catalysis, photochemistry, biochemistry, materials, medicine, magnetism, etc., and have received widespread attention.

[0003] Industrial wastewater often contains pollutants such as organic dyes and nitrite. Organic dyes are widely used in modern industry, but they are often highly toxic, not easy to fade, complex in composition, and poorly degradable. Nitrite is a commonly used food additive that can cause cancer or fetal malformation. Effectively removing organic dye pollutants and nitrite ions is an urgent problem to be solved in current environmental governance. At present, polyacid-based compounds have been proven to have good redox and catalytic properties. Polyacid-based inorganic-organic hybrid materials have better degradation efficiency than traditional water treatment methods, overcoming the problem of difficult catalyst recovery.

[0004] Lanthanide metal ions have some excellent intrinsic properties, such as unique electronic structure and bonding characteristics, high charge, high coordination number and high oxygen affinity. Rare earth compounds are widely used in various fields such as catalysis, optics, and magnetism. Combining rare earth complexes with polyacids can obtain polyacid compounds based on rare earth elements, and the obtained compounds can have the performance characteristics of both polyacids and rare earth complexes. However, since the ability of rare earth metals to form polyacid-based complexes is much smaller than that of transition metals, it is more difficult to synthesize such compounds. At present, there are few studies on the synthesis of polyacid-based rare earth metal complexes, as well as on the optics, electricity, and removal of organic dyes and nitrites of such compounds. Therefore, the present invention prepares a new inorganic-organic hybrid material of polyacid-based cerium complexes, which fills the gap in the prior art.

[0005] Through the above analysis, the problems and defects of the prior art are as follows:

[0006] (1) Traditional methods for treating organic dye pollutants have problems such as poor degradation rate and difficulty in catalyst recovery.

[0007] (2) Since the ability of rare earth metals to form polyacid-based complexes is much smaller than that of transition metals, it is difficult to synthesize polyacid-based rare earth metal complexes.

[0008] (3) Currently, there are very few studies on multifunctional water treatment agents that can remove pollutants such as organic dyes and nitrite, as well as have optical and electrical properties. Summary of the invention

[0009] In view of the problems existing in the prior art, the present invention provides a multi-purpose water treatment agent, a preparation method and an application thereof.

[0010] The present invention is achieved by: a multi-purpose water treatment agent

[0011] [Ce4(C 12 H6N2O4)4(H2O) 10 (SiMo 12 O 40 )]·3H2O,

[0012] The molecular formula is C 48 H 50 N8O 69 Ce4SiMo 12 , molecular weight is 3582.81; the crystal of the multi-purpose water treatment agent is light yellow transparent block crystal; the crystal of the multi-purpose water treatment agent is triclinic system, P-1 space group, and its unit cell parameters are: α=96.03(2)°, β=92.09(2)°, γ=106.82(2)°,

[0013] Furthermore, the multi-purpose water treatment agent is Ce 3+ The deprotonated organic ligand 2,2'-bipyridine-6,6'-dicarboxylic acid forms a two-dimensional complex layered structure containing three-membered rings, four-membered rings and six-membered rings; the polyacid anion (SiMo 12 O 40 ) 4- Filled between the two-dimensional complex layers, the polyacid anions are connected to the complex layers through hydrogen bonding forces to form a three-dimensional supramolecular network structure.

[0014] Furthermore, the deprotonated organic ligand 2,2'-bipyridine-6,6'-dicarboxylic acid is coordinated with Ce in three coordination modes: heptadentate triple bridge μ3-kO,O':kO,N,N',O":k ... 3+ Carry out coordination.

[0015] Furthermore, the Ce 3+ For nine coordination, Ce 3+ The coordination environment includes the following four types:

[0016] (1) A Ce 3+ It is bridged by a carboxyl oxygen from one organic ligand, chelated by two pyridinic nitrogens and two carboxyl oxygens from another organic ligand, and coordinated by four coordinating water molecules;

[0017] (2) A Ce 3+ It is bridged by two carboxyl oxygens from two organic ligands, chelated by two pyridinic nitrogens and two carboxyl oxygens from a third organic ligand, and coordinated by three coordinating water molecules;

[0018] (3) A Ce 3+ It is bridged by three carboxyl oxygens from three organic ligands, chelated by two pyridinic nitrogens and two carboxyl oxygens from a fourth organic ligand, and coordinated by two coordinating water molecules;

[0019] (4) A Ce 3+ It is bridged by a carboxyl oxygen from an organic ligand, chelated by two oxygens of a carboxyl group of an organic ligand, chelated by two pyridinic nitrogens and two carboxyl oxygens of a third organic ligand, and coordinated by two coordinating water molecules.

[0020] Further, the three-membered ring, four-membered ring and six-membered ring structures:

[0021] (1) The three-membered ring is three Ce 3+ A three-membered ring formed by three deprotonated organic ligands 2,2'-bipyridine-6,6'-dicarboxylic acid bridged by carboxyl groups;

[0022] (2) The four-membered ring is four Ce 3+ A four-membered ring formed by four deprotonated organic ligands 2,2'-bipyridine-6,6'-dicarboxylic acid bridged by carboxyl groups;

[0023] (3) The six-membered ring is six Ce 3+ A six-membered ring is formed by five deprotonated organic ligands 2,2'-bipyridine-6,6'-dicarboxylic acid bridged by carboxyl groups.

[0024] Another object of the present invention is to provide a method for preparing a multi-purpose water treatment agent, the method for preparing the multi-purpose water treatment agent comprising:

[0025] Step 1: react Ce(NO3)3·6H2O, C 12H8N2O4 (2,2'-bipyridine-6,6'-dicarboxylic acid), Na2SiO3·9H2O, Na2MoO4·2H2O, H2C2O4·2H2O and 10 mL of purified water were mixed and stirred at room temperature for 30 min;

[0026] Step 2: Use nitric acid reagent and potassium hydroxide reagent to adjust the pH to 3.35, add them into a stainless steel reactor with a polytetrafluoroethylene liner after sufficient reaction and seal them;

[0027] Step 3: The temperature inside the reactor is raised to 100°C, and after constant temperature heating for 4 days, it is cooled to room temperature at a rate of 10°C per hour;

[0028] Step 4: Wash the product in the reactor with pure water to obtain light yellow transparent block crystals, filter them and place them in the air to dry naturally.

[0029] Furthermore, the ratio of the amount of the reactants in step 1 is Ce(NO3)3·6H2O:Na2SiO3·9H2O:Na2MoO4·2H2O:C 12 H8N2O4:H2C2O4·2H2O is 2:2:10:2:1.

[0030] Furthermore, in the step 2, the concentration of the nitric acid reagent is 0.5 mol / L, and the concentration of the potassium hydroxide reagent is 0.5 mol / L.

[0031] Another object of the present invention is to provide a treating agent for photocatalytic degradation of wastewater containing methylene blue organic dye.

[0032] Another object of the present invention is to provide a treatment agent for photocatalytic degradation of wastewater containing Rhodamine-B organic dye.

[0033] Another object of the present invention is to provide a treatment agent for electrocatalytic reduction of industrial wastewater containing nitrite.

[0034] Another object of the present invention is to provide a multifunctional water treatment agent with fluorescent properties.

[0035] In combination with the above technical solutions and the technical problems solved, please analyze the advantages and positive effects of the technical solutions to be protected by the present invention from the following aspects:

[0036] The inorganic-organic hybrid material compound of the polyacid-based cerium complex provided by the present invention is obtained by a hydrothermal synthesis method, wherein the reactants Ce(NO3)3·6H2O, C 12H8N2O4, Na2SiO3·9H2O, Na2MoO4·2H2O, H2C2O4·2H2O and 10mL of pure water were mixed and stirred at room temperature for 30 minutes; nitric acid reagent and potassium hydroxide reagent were used to adjust the pH to 3.35, and after sufficient reaction, they were added to a stainless steel reactor with a polytetrafluoroethylene lining and sealed; they were obtained after constant temperature heating at 100°C for 4 days, and then cooled to room temperature at a cooling rate of 10°C per hour, and the product in the reactor was washed with pure water to obtain light yellow transparent block crystals, which were filtered and placed in the air to dry naturally. Among them, the polyacid anion (SiMo 12 O 40 ) 4- The invention is synthesized in situ by using Na2SiO3·9H2O and Na2MoO4·2H2O under hydrothermal conditions. In the process of forming polyacid anions, it is more conducive to compounding with rare earth complexes to form polyacid-based rare earth metal complexes. The pH value of the reaction system is adjusted to 3.35 by nitric acid reagent and potassium hydroxide reagent. The introduction of nitric acid can avoid the introduction of other anions, while the addition of potassium hydroxide, the introduced potassium ions are more conducive to the formation of rare earth complexes, and the introduction of H2C2O4·2H2O is more conducive to the formation of polyacid compounds. The material can be obtained at a pH value of 3.00-4.00. It is easy to form a perfect crystal under the condition of pH value of 3.35. When the pH value exceeds the range of 3.00-4.00, the material cannot be formed or the obtained material is very small and has too many impurities. Temperature and time are also important factors affecting the synthesis of the material. The material can be obtained at a temperature of 95-105°C and a reaction time of 3-5 days.

[0037] The inorganic-organic hybrid material compound of the polyacid-based cerium complex provided by the present invention [Ce4(C 12 H6N2O4)4(H2O) 10 (SiMo 12 O 40 )] 3H2O, and its molecular formula was determined to be C by X-ray single crystal diffraction. 48 H 50 N8O 69 Ce4SiMo 12 , molecular weight is 3582.81. Its crystal is triclinic system, P-1 space group, and its unit cell parameters are: α=96.03(2)°, β=92.09(2)°, γ=106.82(2)°, The structural characteristics of inorganic-organic hybrid materials of polyacid-based cerium complexes are Ce 3+ The two-dimensional complex layered structure containing four-membered rings and six-membered rings composed of deprotonated organic ligand 2,2'-bipyridine-6,6'-dicarboxylic acid, polyacid anion (SiMo 12 O 40) 4- Filled between the complex layers, the polyacid anions and the complex layers form a three-dimensional supramolecular network structure through hydrogen bonding forces.

[0038] The inorganic-organic hybrid material compound of the polyacid-based cerium complex provided by the present invention is composed of a composite of polyacid anions and a rare earth complex. Since the polyacid anions have good redox and catalytic properties, the material has better degradation efficiency than traditional water treatment methods.

[0039] The inorganic-organic hybrid material compound of the polyacid-based cerium complex provided by the invention is obtained under hydrothermal conditions and is a solid material that is difficult to dissolve in water. After treating pollutants in water, the recovery effect is good.

[0040] The inorganic-organic hybrid material compound of the polyacid-based cerium complex provided by the present invention is a multi-purpose water treatment agent. The material can degrade rhodamine B organic dye wastewater by photocatalysis; the material can degrade methylene blue organic dye wastewater by photocatalysis; the material can also remove nitrite ions in wastewater by electrocatalytic reduction. Since the material is a solid material and is difficult to dissolve in water, the recovery rate of the material is high after removing pollutants in water. At the same time, the material has fluorescence properties and electrochemical properties.

[0041] Second, considering the technical solution as a whole or from the perspective of the product, the technical effects and advantages of the technical solution to be protected by the present invention are described in detail as follows:

[0042] The present invention adopts hydrothermal synthesis technology, the reaction temperature is not high, the reaction time is not long, and the reaction conditions are easy to achieve, so the precision requirements of the device used are not high, and it is easy to obtain on the market, which is a simple and easy preparation process. The synthetic raw materials of the material are cheap and easy to obtain, and the polyacid anions in the obtained material structure are synthesized in situ by cheap Na2SiO3·9H2O and Na2MoO4·2H2O under hydrothermal conditions. The hydrothermal in situ synthesis makes it easier for the polyacid to be compounded with the rare earth complex. The crystal structure of the obtained material is a new structure [Ce4(C 12 H6N2O4)4(H2O) 10 (SiMo 12 O 40 )] 3H2O, whose molecular formula is C 48 H 50 N8O 69 Ce4SiMo 12 , molecular weight is 3582.81. Its crystal is triclinic system, P-1 space group, and its unit cell parameters are: α=96.03(2)°, β=92.09(2)°, γ=106.82(2)°, The obtained material is a solid multi-purpose water treatment agent, which can degrade methylene blue organic dye wastewater by photocatalysis; the material can degrade rhodamine B organic dye wastewater by photocatalysis; the material can also remove nitrite ions in wastewater by electrocatalytic reduction. The material is composed of a composite of polyacid anions and rare earth complexes, wherein the polyacid anions have good redox properties and catalytic properties, so the material has better degradation efficiency than traditional water treatment methods, and the material is a solid material that is difficult to dissolve in water, and has a good recovery effect after treating pollutants in water. Since rare earth metal elements have good optical properties, the material also has good fluorescence properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a flow chart of a method for preparing a multi-purpose water treatment agent provided by an embodiment of the present invention;

[0044] Figure 2 Schematic diagram of three coordination modes of organic ligands in the multi-purpose water treatment agent provided by an embodiment of the present invention;

[0045] Figure 3 It is a schematic diagram of a two-dimensional layered structure containing four-membered rings and six-membered rings composed of metal cerium and deprotonated organic ligand 2,2'-bipyridine-6,6'-dicarboxylic acid in a multi-purpose water treatment agent provided by an embodiment of the present invention;

[0046] Figure 4 It is a schematic diagram of a three-dimensional supramolecular network structure in which polyacid anions are filled between two-dimensional layers formed by metal cerium and deprotonated organic ligand 2,2'-bipyridine-6,6'-dicarboxylic acid in a multi-purpose water treatment agent provided by an embodiment of the present invention, and connected by hydrogen bonding forces;

[0047] Figure 5 is an X-ray powder diffraction spectrum of the multi-purpose water treatment agent provided by an embodiment of the present invention;

[0048] Figure 6 is an infrared spectrum of the multi-purpose water treatment agent provided by an embodiment of the present invention;

[0049] Figure 7 is a solid fluorescence spectrum of the multi-purpose water treatment agent provided by an embodiment of the present invention;

[0050] Figure 8 This is a performance diagram of the multi-purpose water treatment agent provided by an embodiment of the present invention for degrading methylene blue organic dye wastewater;

[0051] Fig. 9 This is a performance diagram of the multi-purpose water treatment agent provided in an embodiment of the present invention for degrading Rhodamine B organic dye wastewater;

[0052] Fig.10 is a cyclic voltammetry curve diagram of the multi-purpose water treatment agent provided by an embodiment of the present invention;

[0053] Fig.11 It is a cyclic voltammetry curve diagram of the electrocatalytic reduction of nitrite by the multi-purpose water treatment agent provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0055] The crystal structure of the material obtained in the embodiment of the present invention is a new structure and a new compound structure [Ce4(C 12 H6N2O4)4(H2O) 10 (SiMo 12 O 40 )] · 3H2O, whose molecular formula is C 48 H 50 N8O 69 Ce4SiMo 12 , molecular weight is 3582.81. Its crystal is triclinic system, P-1 space group, and its unit cell parameters are: α=96.03(2)°, β=92.09(2)°, γ=106.82(2)°,

[0056] Since rare earth metals have much less ability to form polyacid-based complexes than transition metals, it is more difficult to synthesize such compounds. Currently, there is little research on the synthesis of polyacid-based rare earth metal complexes, as well as on the optics, electronics, and removal of organic dyes and nitrite of such compounds.

[0057] At present, 2,2'-bipyridine-6,6'-dicarboxylic acid is only used to synthesize metal organic complexes, and has not been used to synthesize polyacid-based rare earth complexes. At present, there is no polyacid-based rare earth complex synthesized from 2,2'-bipyridine-6,6'-dicarboxylic acid for the treatment of organic dye pollutants or nitrite ion pollutants in water. At present, there is no polyacid-based rare earth complex synthesized from 2,2'-bipyridine-6,6'-dicarboxylic acid that has both fluorescence properties, electrochemical properties, and photocatalytic properties for removing pollutants from water.

[0058] Synthesis experiment: reactants Ce(NO3)3·6H2O, C 12H8N2O4 (2,2'-bipyridine-6,6'-dicarboxylic acid), Na2SiO3·9H2O, Na2MoO4·2H2O, H2C2O4·2H2O and 10 mL of pure water were mixed and stirred at room temperature for 30 min; the ratio of the reactants was Ce(NO3)3·6H2O:Na2SiO3·9H2O:Na2MoO4·2H2O:C 12 H8N2O4:H2C2O4·2H2O is 2:2:10:2:1. The concentration of nitric acid reagent is 0.5 mol / L, the concentration of potassium hydroxide reagent is 0.5 mol / L, the pH is adjusted to 3.35, after sufficient reaction, add to a stainless steel reactor with a polytetrafluoroethylene liner and seal it; 100°C, constant temperature heating for 4 days, cooling to room temperature at a cooling rate of 10°C per hour; the product is washed with pure water to obtain light yellow transparent block crystals, which are filtered and placed in the air to dry naturally.

[0059] like Figure 7 FIG. 1 is a schematic diagram of the solid fluorescence spectrum of the multi-purpose water treatment agent provided by an embodiment of the present invention. Under the excitation of 396 nm light, the emission light generated by the material at 469 nm, 495 nm, and 515 nm can be attributed to Ce 3+ Blue shift after coordination 2 D 5 / 2 - 2 F 7 / 2 jump;

[0060] like Figure 8 As shown, the C / C0 and time relationship diagram of the photocatalytic degradation of methylene blue dye wastewater by the multi-purpose water treatment agent provided in the embodiment of the present invention. 30 mg of the prepared material was added to 40 mg / L methylene blue dye wastewater, and it was placed in the dark and stirred continuously for 15 min to reach adsorption-desorption equilibrium. Then the xenon lamp (300W) was turned on, and 2 mL of the wastewater sample was taken at regular intervals under full spectrum irradiation. After filtering through a 0.45 μm microporous filter membrane, the absorbance value was detected by a UV-visible spectrometer, and then converted into a mass concentration C using the standard curve method, and the degradation rate was calculated using the formula (C0-C) / C0×100%. The experimental results show that the prepared multi-purpose water treatment agent can completely degrade 40 mg / L methylene blue dye wastewater within 120 min, with a degradation rate of 100%. Within 180 min, the solution was continued to be taken for UV-visible spectrum testing, and the degradation rate remained unchanged.

[0061] like Fig. 9As shown, the C / C0 and time relationship diagram of the photocatalytic degradation of Rhodamine B organic dye wastewater by the multi-purpose water treatment agent provided in the embodiment of the present invention. 30 mg of the prepared material was added to 40 mg / L Rhodamine B dye wastewater, and it was placed in the dark and stirred continuously for 15 min to reach adsorption-desorption equilibrium. Then the xenon lamp (300W) was turned on, and 2 mL of the wastewater sample was taken at regular intervals under full spectrum irradiation. After filtering through a 0.45 μm microporous filter membrane, the absorbance value was detected by a UV-visible spectrometer, and then converted into a mass concentration C using the standard curve method, and the degradation rate was calculated using the formula (C0-C) / C0×100%. The experimental results show that the prepared multi-purpose water treatment agent can degrade 40 mg / L Rhodamine B dye wastewater by 98% within 60 min. Within 180 min, the solution was continued to be tested for UV-visible spectroscopy, and the degradation rate remained unchanged.

[0062] It is difficult to combine the rare earth complex provided by the embodiment of the present invention with polyacids. Currently, there are few such compounds. Usually, polyacid photocatalytic degradation of organic dyes is carried out under ultraviolet light irradiation. This material is carried out under full spectrum conditions simulating sunlight conditions. This material is better than containing the same polyacid anion (SiMo 12 O 40 ) 4- The photocatalytic degradation of organic dyes by the compound is much better, and the photocatalytic degradation of dyes is carried out under the full spectrum conditions of simulating natural light, and the material is more practical. 12 O 40 ) 4- The reaction of the compound is usually carried out under ultraviolet light or under other catalyst conditions. For example, within two hours of ultraviolet light, [Ag4(L1)4(SiMo 12 O 40 )] photocatalytic degradation of methylene blue, the degradation rate was only 80.66%, [Cu6(L1)6(H2O)6(SiMo 12 O 40 )3]·6H2O photocatalytic degradation of methylene blue, the degradation rate is only 51.15%. In the presence of catalyst H2O2, [Cu(bipy)4(H2O)4](SiMo 12 O 40 )·18H2O degradation rate of methylene blue is only 85.47%, without H2O2, its degradation rate is only 39.95%

[0063] Under ultraviolet light irradiation,

[0064] {[Ag2(3-bpcd)3][Ag(3-bpcd)(SiMo 12 O 40)]2(3-H2bpcd)2}·7H2O

[0065] The degradation rate of rhodamine B was only about 55% after 60 min and 83% after 150 min.

[0066] TiO2-SiO2 material degrades Rhodamine B under the irradiation of a 500W xenon lamp. The degradation rate is 58% in 30 minutes, about 90% in 60 minutes, and 95.3% in 180 minutes. When the rare earth element Ce is doped to more than 1%, the degradation rate decreases.

[0067] 1. Explanatory Examples In order to enable those skilled in the art to fully understand how to implement the present invention, this section provides an illustrative example that expands and describes the technical solution of the claims.

[0068] like Figure 1 As shown, the preparation method of the multi-purpose water treatment agent provided by the embodiment of the present invention comprises the following steps:

[0069] S101, reactants Ce(NO3)3·6H2O, C 12 H8N2O4 (2,2'-bipyridine-6,6'-dicarboxylic acid), Na2SiO3·9H2O, Na2MoO4·2H2O, H2C2O4·2H2O and 10 mL of purified water were mixed and stirred at room temperature for 30 min;

[0070] S102, using nitric acid reagent and potassium hydroxide reagent to adjust the pH to 3.35, after sufficient reaction, add them into a stainless steel reactor with a polytetrafluoroethylene liner and seal them;

[0071] S103, the temperature inside the reactor is raised to 100°C, kept at this temperature for 4 days, and then cooled to room temperature at a rate of 10°C per hour;

[0072] S104, the product in the reactor is washed with pure water to obtain light yellow transparent block crystals, which are filtered and then placed in the air to dry naturally.

[0073] In the step S101 of the embodiment of the present invention, the ratio of the amount of the reactant substances is Ce(NO3)3·6H2O:Na2SiO3·9H2O:Na2MoO4·2H2O:C 12 H8N2O4:H2C2O4·2H2O is 2:2:10:2:1.

[0074] In step S102 in the embodiment of the present invention, the concentration of the nitric acid reagent is 0.5 mol / L, and the concentration of the potassium hydroxide reagent is 0.5 mol / L.

[0075] The multi-purpose water treatment agent [Ce4(C12 H6N2O4)4(H2O) 10 (SiMo 12 O 40 )] · 3H2O, whose molecular formula is C 48 H 50 N8O 69 Ce4SiMo 12 , molecular weight is 3582.81. Its crystal is triclinic system, P-1 space group, and its unit cell parameters are: α=96.03(2)°, β=92.09(2)°, γ=106.82(2)°,

[0076] Its structure was determined by X-ray single crystal diffractometer, and its structural characteristics are Ce 3+ The deprotonated organic ligand 2,2'-bipyridine-6,6'-dicarboxylic acid forms a two-dimensional complex layered structure containing three-membered rings, four-membered rings and six-membered rings; the polyacid anion (SiMo 12 O 40 ) 4- Filled between the two-dimensional complex layers, the polyacid anions and the complex layers form a three-dimensional supramolecular network structure through hydrogen bonding forces.

[0077] The deprotonated organic ligand 2,2'-bipyridine-6,6'-dicarboxylic acid is coordinated with Ce in three coordination modes: heptadentate triple bridge μ3-kO,O':kO,N,N',O":kO"', hexadentate triple bridge μ3-kO:kO',N,N',O":kO" and hexadentate triple bridge μ3-kO:kO',N,N',O":kO"'. 3+ To coordinate.

[0078] The Ce 3+ For nine coordination, Ce 3+ There are four coordination environments, including: a Ce 3+ It is bridged by a carboxyl oxygen from one organic ligand, chelated by two pyridinic nitrogens and two carboxyl oxygens from another organic ligand, and coordinated by four coordinating water molecules; a Ce 3+ It is bridged by two carboxyl oxygens from two organic ligands, chelated by two pyridinic nitrogens and two carboxyl oxygens from a third organic ligand, and coordinated by three coordinating water molecules; a Ce 3+ It is bridged by three carboxyl oxygens from three organic ligands, chelated by two pyridinic nitrogens and two carboxyl oxygens from a fourth organic ligand, and coordinated by two coordinating water molecules; a Ce 3+It is bridged by a carboxyl oxygen from an organic ligand, chelated by two oxygens of a carboxyl group of an organic ligand, chelated by two pyridinic nitrogens and two carboxyl oxygens of a third organic ligand, and coordinated by two coordinating water molecules.

[0079] The three-membered ring is three Ce 3+ The three-membered ring is formed by three deprotonated organic ligands 2,2'-bipyridine-6,6'-dicarboxylic acid bridged by carboxyl groups; the four-membered ring is four Ce 3+ The four-membered ring is formed by four deprotonated organic ligands 2,2'-bipyridine-6,6'-dicarboxylic acid bridged by carboxyl groups; the six-membered ring is six Ce 3+ A six-membered ring is formed by five deprotonated organic ligands 2,2'-bipyridine-6,6'-dicarboxylic acid bridged by carboxyl groups.

[0080] 2. Application Examples: In order to prove the creativity and technical value of the technical solution of the present invention, this section provides application examples of the technical solution of the claims on specific products or related technologies.

[0081] The multi-purpose water treatment agent provided by the embodiment of the present invention can be used for photocatalytic degradation of wastewater containing rhodamine-B organic dye and wastewater containing methylene blue organic dye, and can also be used for electrocatalytic reduction of industrial wastewater containing nitrite.

[0082] 3. Evidence of the effects of the embodiments. The embodiments of the present invention have achieved some positive effects during the development or use process, and indeed have great advantages over the prior art. The following content is described in conjunction with the data, charts, etc. of the test process.

[0083] The multi-purpose water treatment agent provided by the embodiment of the present invention can efficiently remove organic dye pollutants and nitrite ions. The material can photocatalytically degrade rhodamine B organic dye wastewater and methylene blue organic dye wastewater. The material can also remove nitrite ions in wastewater by electrocatalytic reduction. At the same time, the material also has fluorescence properties and electrochemical properties.

[0084] Table 1 Crystallographic parameters of compounds

[0085]

[0086] The technical solution of the present invention is further described below in conjunction with experiments.

[0087] Figure 2Schematic diagram of three coordination modes of organic ligands in the multi-purpose water treatment agent provided in an embodiment of the present invention, the coordination modes of the organic ligands are: μ3-kO,O′:kO,N,N′,O″:kO″′; μ3-kO:kO′,N,N′,O″:kO″; μ3-kO:kO′,N,N′,O″:kO″′.

[0088] like Figure 3 As shown, Ce in the multi-purpose water treatment agent provided by the embodiment of the present invention 3+ and the deprotonated organic ligand 2,2'-bipyridine-6,6'-dicarboxylic acid to form a two-dimensional layered structure. 3+ They are connected by organic ligands to form three types of ring structures: three-membered ring, four-membered ring and six-membered ring.

[0089] like Figure 4 As shown, the polyacid anion [SiMo 12 O 40 ] 4- Filled in Ce 3+ Between the two-dimensional layer formed by the deprotonated organic ligand 2,2'-bipyridine-6,6'-dicarboxylic acid, hydrogen bonding forces connect the crystal water, polyacid anions and the two-dimensional layer to form a three-dimensional supramolecular network structure.

[0090] Figure 5 The X-ray powder diffraction spectrum of the multi-purpose water treatment agent provided in the embodiment of the present invention is consistent well with the simulated spectrum measured in the experiment, indicating that the phase purity of the material is very good.

[0091] Figure 6 The infrared spectrum of the multi-purpose water treatment agent provided in the embodiment of the present invention is 953, 903, 811, 759 cm -1 The characteristic absorption peaks at 1569, 1433, 1388 cm-1 can be attributed to the characteristic absorption peaks of νSi-Oa, νMo-Od, νMo-Oc-Mo, and νMo-Od-Mo of the polyoxometalate anion [SiMo12]. -1 The absorption peak at 3400cm -1 The nearby peaks can be attributed to the characteristic absorption peaks of -OH of coordinated water and crystal water in the compound.

[0092] Figure 7 Schematic diagram of the solid fluorescence spectrum of the multi-purpose water treatment agent provided in an embodiment of the present invention. Under the excitation of 396nm light, the emission light generated by the material at 469nm, 495nm, and 515nm can be attributed to Ce 3+ Blue shift after coordination 2 D 5 / 2 -2 F 7 / 2 jump;

[0093] Figure 8 The C / C0 and time relationship diagram of the multi-purpose water treatment agent for photocatalytic degradation of methylene blue dye wastewater provided in the embodiment of the present invention. 30 mg of the prepared material was added to 40 mg / L methylene blue dye wastewater, darkened and stirred continuously for 15 min to reach adsorption-analysis equilibrium. Then turn on the xenon lamp (300W), take 2 mL of wastewater sample at regular intervals under full spectrum irradiation, filter through 0.45 μm microporous filter membrane, detect its absorbance value by ultraviolet visible spectrometer, and then convert it into mass concentration C by standard curve method, and calculate the degradation rate by formula (C0-C) / C0×100%. The experimental results show that the prepared multi-purpose water treatment agent can completely degrade 40 mg / L methylene blue dye wastewater within 120 min, with a degradation rate of 100%. Within 180 min, continue to take the solution for ultraviolet visible spectrum test, and the degradation rate remains unchanged.

[0094] Fig. 9 The C / C0 and time relationship diagram of the photocatalytic degradation of Rhodamine B organic dye wastewater by the multi-purpose water treatment agent provided in the embodiment of the present invention. 30 mg of the prepared material was added to 40 mg / L Rhodamine B dye wastewater, and it was placed in the dark and stirred continuously for 15 min to reach adsorption-desorption equilibrium. Then the xenon lamp (300W) was turned on, and 2 mL of the wastewater sample was taken at regular intervals under full spectrum irradiation. After filtering through a 0.45 μm microporous filter membrane, its absorbance value was detected by a UV-visible spectrometer, and then converted into a mass concentration C by the standard curve method, and the degradation rate was calculated by the formula (C0-C) / C0×100%. The experimental results show that the prepared multi-purpose water treatment agent can degrade 40 mg / L Rhodamine B dye wastewater by 98% within 60 min. Within 180 min, the solution was continued to be tested for UV-visible spectroscopy, and the degradation rate remained unchanged.

[0095] Fig.10 The cyclic voltammogram of the carbon paste electrode made of the compound provided in the embodiment of the present invention in 0.1mol / LH2SO4 and 0.1mol / LNa2SO4 solution, the scanning speed from inside to outside is 20, 40, 60, 80, 100, 200, 300mV / s respectively. The half-wave potential (E1 / 2=EPA+EPC / 2) is 0.27 (Ⅰ-Ⅰ'), 0.15 (Ⅱ-Ⅱ'), -0.066 (Ⅲ-Ⅲ'). The three pairs of redox peaks of Ⅰ-Ⅰ', II-II', III-III' of compound 1 can be attributed to the continuous transfer of two, four and six electrons of molybdenum atoms in POM.

[0096] Fig.11The cyclic voltammogram of the electrocatalytic reduction of nitrite ions by the multi-purpose water treatment agent provided in the embodiment of the present invention. Under the condition of a scan rate of 100 mV / s, as nitrite ions are continuously added (nitrite ion concentrations are 0, 2, 4, 6, 8, 10 mm, respectively), the reduction peak current increases continuously and the oxidation peak current decreases continuously, indicating that the compound has a catalytic effect on the electrocatalytic reduction of nitrite ions.

[0097] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A multi-purpose water treatment agent, characterized in that: The molecular formula of the multi-purpose water treatment agent is C 48 H 50 N8O 69 Ce4SiMo 12 , the chemical formula is [Ce4(C 12 H6N2O4)4(H2O) 10 (SiMo 12 O 40 )]·3H2O, molecular weight is 3582.81; its crystal is triclinic system, P-1 space group, and its unit cell parameters are: α＝96.03(2)°，β＝92.09(2)°， γ=106.82(2)°, The C 12 H6N2O4 is the deprotonated organic ligand 2,2'-bipyridine-6,6'-dicarboxylic acid; The multi-purpose water treatment agent is Ce 3+ Coordinated with the deprotonated organic ligand 2,2'-bipyridine-6,6'-dicarboxylic acid to form a two-dimensional layered structure containing three-membered rings, four-membered rings and six-membered rings; the polyacid anion (SiMo 12 O 40 ) 4- Filled between the layers, the polyacid anions and the complex layers form a three-dimensional supramolecular network structure through hydrogen bonding forces; The three-membered ring is three Ce 3+ The three-membered ring is formed by three deprotonated organic ligands 2,2'-bipyridine-6,6'-dicarboxylic acid bridged by carboxyl groups; the four-membered ring is four Ce 3+ The four-membered ring is formed by four deprotonated organic ligands 2,2'-bipyridine-6,6'-dicarboxylic acid bridged by carboxyl groups; the six-membered ring is six Ce 3+ A six-membered ring is formed by five deprotonated organic ligands 2,2'-bipyridine-6,6'-dicarboxylic acid bridged by carboxyl groups.

2. The multi-purpose water treatment agent according to claim 1, characterized in that: The deprotonated organic ligand 2,2'-bipyridine-6,6'-dicarboxylic acid is coordinated with Ce in three coordination modes: heptadentate triple bridge μ3-kO,O':kO,N,N',O":k ... 3+ To coordinate.

3. The multi-purpose water treatment agent according to claim 1, characterized in that: The Ce 3+ For nine coordination, Ce 3+ The coordination environment includes the following four types: (1) A Ce 3+ It is bridged by a carboxyl oxygen from one organic ligand, chelated by two pyridinic nitrogens and two carboxyl oxygens from another organic ligand, and coordinated by four coordinating water molecules; (2) A Ce 3+ It is bridged by two carboxyl oxygens from two organic ligands, chelated by two pyridinic nitrogens and two carboxyl oxygens from a third organic ligand, and coordinated by three coordinating water molecules; (3) A Ce 3+ It is bridged by three carboxyl oxygens from three organic ligands, chelated by two pyridinic nitrogens and two carboxyl oxygens from a fourth organic ligand, and coordinated by two coordinating water molecules; (4) A Ce 3+ It is bridged by a carboxyl oxygen from an organic ligand, chelated by two oxygens of a carboxyl group of an organic ligand, chelated by two pyridinic nitrogens and two carboxyl oxygens of a third organic ligand, and coordinated by two coordinating water molecules.

4. A method for preparing the multi-purpose water treatment agent according to any one of claims 1 to 3, characterized in that: The preparation method of the multi-purpose water treatment agent comprises: Step 1: react Ce(NO3)3·6H2O, C 12 H8N2O4, Na2SiO3·9H2O, Na2MoO4·2H2O and 10 mL of pure water were mixed and stirred at room temperature for 30 min; Step 2: Use nitric acid reagent and potassium hydroxide reagent to adjust the pH to 3.35, add them into a stainless steel reactor with a polytetrafluoroethylene liner after sufficient reaction and seal them; Step 3: The temperature inside the reactor was raised to 100°C, kept at a constant temperature for 4 days, and then cooled to room temperature at a rate of 10°C per hour; Step 4: Wash the product in the reactor with pure water to obtain light yellow transparent block crystals, filter them and place them in the air to dry naturally.

5. The method for preparing a multi-purpose water treatment agent according to claim 4, characterized in that: The ratio of the amount of reactants in step 1 is Ce(NO3)3·6H2O:Na2SiO3·9H2O:Na2MoO4·2H20:C 12 H8N2O4:H2C2O4·2H2O is 2:2:10:2:

1.

6. The method for preparing a multi-purpose water treatment agent according to claim 4, characterized in that: In the step 2, the concentration of the nitric acid reagent is 0.5 mol / L, and the concentration of the potassium hydroxide reagent is 0.5 mol / L.

7. A method for treating wastewater using the multi-purpose water treatment agent according to any one of claims 1 to 4, characterized in that: Add 30 mg of the prepared material to 40 mg / L methylene blue dye wastewater, place it in the dark and continue stirring for 15 minutes to reach adsorption-desorption equilibrium; then turn on the xenon lamp, and take 2 mL of wastewater sample at regular intervals under full spectrum irradiation. After filtering through a 0.45 μm microporous filter membrane, use an ultraviolet-visible spectrometer to detect its absorbance value, and then use the standard curve method to convert it into mass concentration C. The degradation rate is calculated using the formula (C0-C) / C0×100%, and the initial concentration C0 of the dye in the wastewater is C0.

8. A method for treating wastewater using the multi-purpose water treatment agent according to any one of claims 1 to 4, characterized in that: Add 30 mg of the prepared material to 40 mg / L Rhodamine B dye wastewater, place it in the dark and continue stirring for 15 minutes to reach adsorption-desorption equilibrium; then turn on the xenon lamp, and take 2 mL of wastewater sample at regular intervals under full spectrum irradiation. After filtering through a 0.45 μm microporous filter membrane, use an ultraviolet-visible spectrometer to detect its absorbance value, and then use the standard curve method to convert it into mass concentration C. The degradation rate is calculated using the formula (C0-C) / C0×100%, and the initial concentration C0 of the dye in the wastewater is.

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