Supramolecular cage complex, preparation method thereof and application of supramolecular cage complex in wastewater treatment

Abstract

The invention discloses a supramolecular cage complex, a preparation method and an application of the supramolecular cage complex in wastewater treatment, and the supramolecular cage complex with a cavity structure is applied to catalytic treatment of wastewater, in particular to treatment of oxidative degradation of dye molecules or antibiotics by persulfate. Through the porous cavity structure, the enrichment of persulfate and organic matters thereof can be realized, not only can peroxymonosulfate (PMS) and peroxydisulfate (PDS) be efficiently activated to generate non-free radicals, but also the peroxymonosulfate (PMS) and the peroxydisulfate (PDS) are in better contact with the organic matters, so that a more efficient oxidative degradation treatment effect is achieved; experiments prove that the catalyst has a wide catalytic acid-base environment, can adapt to the catalytic environment with the pH value of 3-11, is higher in catalytic stability and small in environmental limitation, and can be recycled.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a supramolecular cage complex, a preparation method thereof and application thereof in wastewater treatment. Background Art

[0002] Advanced oxidation technology based on sulfate has the advantages of strong oxidation ability, high mineralization rate, and wide pH application range, and has broad application prospects in the field of purifying difficult-to-degrade organic wastewater. Permonosulfate (PMS) and peroxydisulfate (PDS) are both persulfates (PS) and are commonly used wastewater treatment agents. They mainly achieve wastewater treatment by oxidative degradation of difficult-to-degrade organic matter. However, the peroxy bond breaking of peroxymonosulfate (PMS) and peroxydisulfate (PDS) generally requires high energy to produce free radicals, and the energy consumption of excitation methods such as ultrasound, light, and heat is large. Therefore, in the process of using peroxymonosulfate (PMS) and peroxydisulfate (PDS) for wastewater treatment, catalysts are needed to promote oxidative degradation reactions. However, the commonly used transition metal ion homogeneous catalysts have certain disadvantages, such as the difficulty in recovering dissolved metal ions, the easy secondary pollution of metal ions, the water quality components and pH will affect the transition metal ions, and the activation will be affected by the complexation of some organic compounds and metal ions in the wastewater. Therefore, it is necessary to develop more efficient and stable transition metal catalysts.

[0003] The coordination molecular container constructed by metal coordination bonds has a unique cavity structure, which can selectively contain guest molecules with specific size, configuration and functional groups to achieve the enrichment of specific compounds. In addition, since the molecular container has a stable structure and metal-O coordination bonds, it is possible to use it as a catalyst for wastewater treatment. Summary of the invention

[0004] Therefore, based on the above background, the present invention provides a supramolecular cage complex, a preparation method and an application in wastewater treatment, which can efficiently activate permonosulfate (PMS) and peroxydisulfate (PDS) to efficiently catalyze permonosulfate (PMS) and peroxydisulfate (PDS) to oxidatively degrade difficult-to-degrade organic matter in dye wastewater or pharmaceutical wastewater.

[0005] The technical solution provided by the present invention is:

[0006] A supramolecular cage complex, characterized in that the general structural formula of the supramolecular cage complex is shown in the following formula (1):

[0007] [M a (μ4-H2O)(X)]2Y4(1);

[0008] in:

[0009] a is 4 or 8;

[0010] M is at least one selected from magnesium, zinc, manganese, cobalt, nickel, copper, iron, or ruthenium;

[0011] μ4-H2O represents that 4 M atoms form a 4-coordination pattern with the O atoms in H2O;

[0012] X is a thiacalix[4]arene ligand, and its molecular structure is shown in the following formula (2):

[0013]

[0014] In formula (2), R1, R2, R3, and R4 are the same or different and are independently selected from hydrogen, alkyl, and aryl;

[0015] A1, A2, A3, A4 are the same or different and are independently selected from -S-, -SO-, -SO2-;

[0016] Y is a dicarboxylic acid ligand, and its molecular structure is shown in the following formula (3):

[0017]

[0018] Furthermore, R1, R2, R3, and R4 in formula (2) are each selected from tert-butyl, tert-octyl, and phenyl.

[0019] Furthermore, A1, A2, A3, and A4 in formula (2) are respectively -SO2-.

[0020] Furthermore, the supramolecular cage complex is [Co4(μ4-H2O)(TBSC)]2[ADC]4, wherein TBSC represents 5,11,17,23-tetra-tert-butyl-sulfonyl-bridged calix[4]arene ligand, and ADC represents 1,3-adamantanedicarboxylic acid ligand.

[0021] Based on the same inventive concept, the present invention also provides a method for preparing a supramolecular cage complex, comprising the following steps: subjecting H4X, H2Y and M metal salts to a self-assembly reaction in an organic solvent to obtain a supramolecular cage complex, wherein X, Y and M are as defined above.

[0022] Further, the molar ratio of X:Y:M is (0.9-1.1):(1.8-4.5):(4.0-7.0).

[0023] Furthermore, the organic solvent is an amide solvent, or a mixed solvent of amide and alcohol.

[0024] Preferably, the organic solvent is N,N'-dimethylformamide (DMF), or a mixed solvent of N,N'-dimethylformamide and methanol.

[0025] More specifically, the organic solvent is a mixed solvent of N,N'-dimethylformamide and methanol in a volume ratio of 1:1.

[0026] Furthermore, in the above preparation method, the reaction temperature is controlled at 80-140°C; preferably, the reaction is carried out at a temperature of 100-120°C.

[0027] Furthermore, the M metal salt is a nitrate or a halogenated salt.

[0028] Based on the same inventive concept, the present invention also applies the supramolecular cage complex as a catalyst to wastewater treatment, wherein the wastewater contains at least one of a dye or an antibiotic.

[0029] The dye includes at least one of methylene blue, rhodamine B, and eosin Y, and the antibiotic includes at least one of tetracycline and enrofloxacin.

[0030] Furthermore, the supramolecular cage complex is used as a heterogeneous catalyst for the oxidation degradation of organic matter system by a persulfate system.

[0031] The above technical solution has the following beneficial effects:

[0032] The present invention applies a supramolecular cage complex with a cavity structure to catalytically degrade organic matter in wastewater, especially to the treatment of persulfate oxidation degradation of dye molecules or antibiotics. The porous cavity structure can achieve the enrichment of persulfate and its organic matter, and can not only efficiently activate peroxymonosulfate (PMS) and peroxydisulfate (PDS), but also make peroxymonosulfate (PMS) and peroxydisulfate (PDS) better contact with organic matter, thus achieving a more efficient oxidation degradation treatment effect.

[0033] It has been verified through experiments that the catalyst of the present invention has a wide catalytic acid-base environment, can adapt to a catalytic environment with a pH of 3-11, and has higher catalytic stability.

[0034] The supramolecular cage complex of the present invention, as a catalyst in a persulfate oxidation degradation system for organic matter, has excellent recycling capability and still has high catalytic performance when it is reused for at least the third time. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Attached Figure 1 This is a schematic diagram of the crystal structure of the supramolecular cage complex prepared in Example 1. For ease of viewing, all H atoms have been omitted;

[0036] Attached Figure 2Schematic diagram of the crystal structure of the supramolecular cage complex prepared in Example 1, wherein the inner cavity is filled with virtual yellow spheres, and the outer cavity is filled with virtual green spheres;

[0037] Attached Figure 3 The supramolecular cage complex crystal prepared in Example 1 is used as a catalyst, and the effect of its addition amount on the catalytic degradation performance of methylene blue;

[0038] Attached Figure 4 The effect of the supramolecular cage complex crystal prepared in Example 1 on the catalytic degradation of different types of pollutants (rhodamine B, eosin Y, tetracycline, and enrofloxacin).

[0039] Attached Figure 5 The figure is a comparison of the catalytic efficiency of different catalysts according to the embodiments of the present invention.

[0040] Attached Figure 6 This is a graph showing the results of the cyclic experiment of the supramolecular cage complex prepared in Example 1.

[0041] Attached Figure 7 The catalytic performance of different supramolecular cage catalysts is compared in Example.

[0042] Attached Figure 8 The invention discloses the cyclic performance of the supramolecular cage complex for secondary and tertiary catalysis. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0045] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0046] Example 1: Preparation of supramolecular cage complexes

[0047] The structural formula of the supramolecular cage complex of this embodiment is shown below:

[0048] [Co4(μ4-H2O)(TBSC)]2[ADC]4

[0049] Where TBSC represents 5,11,17,23-tetra-tert-butyl-sulfonyl-bridged calix[4]arene ligand, DC represents 1,3-adamantanedicarboxylic acid ligand;

[0050] Figure 1 FIG. 1 is a schematic diagram of the crystal structure of the supramolecular cage complex of this embodiment. Figure 1 It can be seen that a supramolecular cage complex molecule is obtained by bridging two tetranuclear metal calix[4]arene structural units with four 1,3-adamantanedicarboxylic acid ligands, and has a supramolecular cage structure with a square box configuration. The supramolecular cage complex molecule also contains two outer cavities composed of calixarene and an inner cavity composed of diacid bridging ligands and tetranuclear metal calixarene. These inner and outer cavity structures can be used to effectively bind and contain guest molecules ( Figure 2 ).

[0051] The specific preparation process is as follows:

[0052] Co(NO3)2·6H2O (72.80 mg, 0.25 mmol), 1,3-adamantanedicarboxylic acid (33.60 mg, 0.15 mmol) and H4TBSC (42.50 mg, 0.05 mmol) were dissolved in 3 mL of N,N'-dimethylformamide (DMF) and 3 mL of methanol mixed solvent, heated to 100°C at a heating rate of 0.5°C / min, maintained at 100°C for 24 h and then cooled at a rate of 0.2°C / min to obtain red crystals. The yield was calculated to be 85%.

[0053] The product was characterized by X-ray single crystal diffraction, and the specific results are as follows:

[0054] Table 1: Crystallographic parameters of [Co4(μ4-H2O)(TBSC)]2[ADC]4

[0055]

[0056] The above data show that the target product [Co4(μ4-H2O)(TBSC)]2[ADC]4 (wherein TBSC represents 5,11,17,23-tetra-tert-butyl-sulfonyl-bridged calix[4]arene ligand and ADC represents 1,3-adamantanedicarboxylic acid ligand) was obtained in this example.

[0057] Example 2: In this example, the supramolecular cage complex prepared in Example 1 is used as a catalyst in a persulfate wastewater treatment system.

[0058] When the supramolecular cage complex prepared in Example 1 is used as a Fenton-like catalyst, it mainly activates peroxymonosulfate or peroxydisulfate to produce non-free radicals to oxidize and degrade organic matter in wastewater. The organic matter includes methylene blue (MB), rhodamine B, eosin Y, tetracycline, enrofloxacin and other difficult-to-degrade organic matter.

[0059] Specifically, monosulfate (PMS) was used as a wastewater treatment agent and the supramolecular cage complex prepared in Example 1 was used as a catalyst to treat wastewater containing methylene blue.

[0060] ① During the experiment, methylene blue was added to water to prepare the wastewater to be oxidized and degraded, and the initial concentration of methylene blue was 20 mg / L;

[0061] The initial pH value was controlled at 6.9-7.1, the temperature was 20°C, the peroxymonosulfate concentration was controlled at 0.4 g / L, and then the supramolecular cage complex concentrations were controlled at 0.02 g / L, 0.06 g / L, 0.10 g / L, 0.14 g / L, and 0.18 g / L, respectively. Under stirring conditions, the effect of the amount of peroxymonosulfate added on the degradation efficiency of methylene blue was investigated. The results are shown in Figure 3 .

[0062] The initial pH value was controlled at 6.9-7.1, the temperature was 20°C, the addition concentration of the supramolecular cage complex was controlled at 0.1 g / L, and then the addition concentration of peroxymonosulfate was controlled at 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, and 0.5 g / L, respectively. Under stirring conditions, the effect of the addition amount of the supramolecular cage complex on the degradation efficiency of methylene blue was investigated. The results are shown in Figure 4 .

[0063] Depend on Figure 3 It can be seen that the amount of supramolecular cage complex added has a great influence on the catalytic degradation performance of methylene blue. When the amount of catalyst added increases from 0.02 g / L to 0.18 g / L, the degradation efficiency of MB within 3 min gradually increases. Figure 4 It can be seen that the amount of peroxymonosulfate has little effect on the degradation of methylene blue.

[0064] ② Add methylene blue into ultrapure water to prepare a methylene blue test solution with a concentration of 20 mg / L, which serves as the wastewater to be oxidized and degraded.

[0065] Take 4 portions of 50 mL of 20 mg / L methylene blue solution (control the initial pH at 6.9-7.1), 1 portion as the control group and 3 portions as the experimental group, add 0.5 mM anion (Cl - 、HPO4 2- 、HCO32- ), mixed evenly, the temperature was 20°C, the concentration of persulfate added was 0.4 g / L, the dosage of supramolecular cage complex was 0.1 g / L, and under stirring conditions, the effects of different types of anions on the degradation efficiency were investigated. The results are as follows Figure 5 shown.

[0066] Depend on Figure 5 It can be seen that compared with the control group, adding different types of anions (Cl - 、HPO4 2- 、HCO3 2- ) has almost no effect on the overall degradation, and can reach more than 99% degradation within 30 minutes.

[0067] ③ Take multiple 50mL samples of 20mg / L methylene blue aqueous solution, adjust the pH of the methylene blue solution to 3, 5, 7, 9, and 11 with 0.1M H2SO4 and NaOH, then add 5mg supramolecular cage complex and 20mg PMS to the samples to explore the effect of pH on catalytic efficiency. The results are shown in Figure 6 .

[0068] Depend on Figure 6 It can be seen that within a wide pH range, the supramolecular cage complex can still catalyze the degradation of methylene blue by PMS to greater than 99% within 20 minutes.

[0069] ④Comparison of catalytic performance of different supramolecular cage catalysts

[0070] The comparative catalysts are triazine supramolecular cage and triphenylamine supramolecular cage.

[0071] The preparation procedure of triazine supramolecular cages is as follows:

[0072] Co(NO3)2·6H2O (72.75 mg, 0.25 mmol), H4TBSC (42.2 mg, 0.05 mmol), 4,4',4"-s-triazine-2,4,6-triyl-tribenzoic acid (66.21 mg, 0.15 mmol) were weighed and dissolved in a mixed solution of 4 mL N,N'-dimethylformamide (DMF) and 3 mL methanol, and heated to 120°C at a heating rate of 0.5°C / min. The temperature was maintained at 120°C for 24 h and then cooled at a rate of 0.2°C / min to obtain red crystals B;

[0073] The preparation procedure of triphenylamine supramolecular cage is as follows:

[0074] Co(NO3)2·6H2O (72.75 mg, 0.25 mmol), H4TBSC (42.2 mg, 0.05 mmol), 4,4'4"-tricarboxylic acid triphenylamine (56.6 mg, 0.15 mmol) were weighed and dissolved in a mixed solution of 4 mL N,N'-dimethylformamide (DMF) and 3 mL methanol, heated to 120°C at a heating rate of 0.5°C / min, maintained at 120°C for 24 h, and then cooled at a rate of 0.2°C / min to obtain a red product C;

[0075] 5 mg of the supramolecular cage complex (Ada-MOSC), triazine supramolecular cage and triphenylamine supramolecular cage prepared in Example 1 were added to 50 mL of a 10 mg / L methylene blue aqueous solution (pH of about 6.9-7.1) (referred to as reactions A, B and C). After dark adsorption for 30 min, 20 mg of PMS was added to the AC solutions respectively. The degradation efficiency of methylene blue in the three solutions within 30 minutes was measured by UV-vis, and the catalytic efficiency of the three catalysts was evaluated by the absorbance at 664 nm. The results are shown in FIG. Figure 7 As shown. Figure 7 It can be seen that the catalytic degradation efficiency of the supramolecular cage complex Ada-MOSC in Example 1 is the highest compared with the other two catalysts, and 99% of methylene blue can be degraded within 10 minutes.

[0076] ⑤ Based on the above experiment ④, the supramolecular cage complex (Ada-MOSC) after catalytic degradation was collected, vacuum dried, and used as a catalyst again according to the above degradation conditions. The specific operation was as follows:

[0077] 5 mg of the collected supramolecular cage complex was added to 50 mL of a 10 mg / L methylene blue aqueous solution. After dark adsorption for 30 min, 20 mg of PMS was added to the solution. The degradation efficiency of methylene blue was determined by UV-vis, and the absorbance at 664 nm was used to evaluate the catalytic efficiency. The result curve was counted as 2st.

[0078] The catalyst after the catalytic degradation was collected again, vacuum dried, and used as a catalyst for the third time under the same degradation conditions as above. The degradation efficiency of methylene blue was continued to be determined by UV-vis, and the catalytic efficiency was evaluated by the absorbance at 664nm. The result curve was counted as 3st.

[0079] Combined with the results of experiment ④ above, the supramolecular cage complex prepared in Example 1 was subjected to secondary and tertiary catalytic experiments, and the catalytic conditions were not changed to evaluate its recycling performance. The results are as follows: Figure 8 As shown. Figure 8It can be seen that when the catalyst is used for the third time, its catalytic performance is still very significant, and it can catalyze the degradation of methylene blue by PMS to more than 99% within 30 minutes. Therefore, it is obvious that the supramolecular cage complex of the present invention has high efficiency and stable catalytic activity for the oxidation degradation of pollutants by PMS as a Fenton-like catalyst, has little environmental restriction, and can be recycled.

[0080] The present invention and its implementation methods are described above, and such description is not restrictive, and the actual methods are not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design implementation methods and embodiments similar to the technical solution without creativity, which should all fall within the protection scope of the present invention.

Claims

1. A supramolecular cage complex, characterized in that: The general structural formula of the supramolecular cage complex is shown in the following formula (1): [M a (μ4-H2O)(X)]2Y4(1); in: a is 4 or 8; M is at least one selected from magnesium, zinc, manganese, cobalt, nickel, copper, iron, or ruthenium; μ4-H2O represents that 4 M atoms form a 4-coordination pattern with the O atoms in H2O; X is a thiacalix[4]arene ligand, and its molecular structure is shown in the following formula (2): In formula (2), R1, R2, R3, and R4 are the same or different and are independently selected from hydrogen, alkyl, and aryl; A1, A2, A3, A4 are the same or different and are independently selected from -S-, -SO-, -SO2-; Y is a dicarboxylic acid ligand, and its molecular structure is shown in the following formula (3): 。 2. A supramolecular cage complex according to claim 1, characterized in that: In formula (2), R1, R2, R3 and R4 are selected from tert-butyl, tert-octyl and phenyl groups respectively.

3. A supramolecular cage complex according to claim 2, characterized in that: In formula (2), A1, A2, A3 and A4 are respectively -SO2-.

4. A supramolecular cage complex according to claim 3, characterized in that: The supramolecular cage complex is [Co4(μ4-H2O)(TBSC)]2[ADC]4, wherein TBSC represents 5,11,17,23-tetra-tert-butyl-sulfonyl bridged calix[4]arene ligand, and ADC represents 1,3-adamantanedicarboxylic acid ligand.

5. A method for preparing a supramolecular cage complex according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: subjecting H4X, H2Y and M metal salts to a self-assembly reaction in an organic solvent to obtain a supramolecular cage complex, wherein X, Y and M are as defined in any one of claims 1-4.

6. The method for preparing a supramolecular cage complex according to claim 5, characterized in that: The molar ratio of X:Y:M is (0.9-1.1):(1.8-4.5):(4.0-7.0).

7. The method for preparing a supramolecular cage complex according to claim 5, characterized in that: The M metal salt is a nitrate or a halogenated salt.

8. Use of a supramolecular cage complex according to any one of claims 1 to 4, or a supramolecular cage complex prepared by the preparation method according to any one of claims 5 to 7 as a catalyst in wastewater treatment, characterized in that: The wastewater contains at least one of a dye or an antibiotic.

9. The use according to claim 8, characterized in that: The dye includes at least one of methylene blue, rhodamine, and eosin, and the antibiotic includes at least one of tetracycline and enrofloxacin.

10. The use according to claim 8, characterized in that: The supramolecular cage complex is used as a heterogeneous catalyst for the persulfate system to oxidize and degrade an organic matter system.

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