Imine bidentate ligand for removing metal ions, preparation method of imine bidentate ligand, metal complex and application of imine bidentate ligand

Abstract

The invention relates to the technical field of new material synthesis and wastewater treatment, in particular to an imine bidentate ligand for removing metal ions, a preparation method of the imine bidentate ligand, a metal complex and application of the imine bidentate ligand, and the imine bidentate ligand has the capability of removing most of metal ions such as Cu < 2 + >, Fe < 3 + >, Ni < 2 + >, Co < 2 + > and Pb < 2 + > ions. And the imine bidentate ligand has a high removal rate on metal ions. According to the preparation method of the imine bidentate ligand, the imine bidentate ligand is prepared through a one-step synthesis method, the synthesis method is simple, large-scale production is facilitated, raw materials are low in price, and the preparation cost is low. The application of the imine bidentate ligand for removing the metal ions in polluted environment restoration or wastewater treatment has the advantages of low operation cost, high metal ion removal efficiency and strong potential. The metal complex has excellent photo-thermal performance and has a good application prospect in photo-thermal conversion.

Description

Technical Field

[0001] The present invention relates to the technical field of new material synthesis and wastewater treatment, and in particular to an imine bidentate ligand for removing metal ions, a preparation method thereof, a metal complex and applications thereof. Background Art

[0002] With the development and surge of industry, most water sources have been polluted to varying degrees. Among them, heavy metal ions are the most harmful. Due to their strong carcinogenicity, toxicity and non-biodegradable properties, these heavy metal cations will bioaccumulate and biomagnify in different ecosystems, thereby increasing their dangerous effectiveness. This has become a serious global problem, so there is an urgent need to introduce technologies to repair polluted environmental components.

[0003] A variety of technologies and methods have been developed for removing metal ions, including ion exchange, electrolysis, and ultrafiltration. However, these methods are associated with high operating costs and low metal cation removal efficiency. In recent years, Schiff base ligands, prepared by the condensation of amines and aldehydes, have been shown to be very effective chelating agents. They have attracted widespread attention due to their simplicity, low cost, and high metal cation removal efficiency compared to ion exchange, electrolysis, and ultrafiltration methods, and have great potential for remediation of contaminated environments and wastewater treatment.

[0004] Among them, heavy metal ions that usually need to be removed include Cu 2+ 、Fe 3+ 、Co 2+ 、Ni 2+ , Pb 2+ When used as metal ion chelating agents, Schiff base ligands prepared by the condensation of amines and aldehydes in the prior art typically have a removal rate of 90% to 94% for these metal ions. Therefore, the metal ion removal rate of chelating agents prepared in the prior art needs to be further improved. Furthermore, the prior art preparation of Schiff base ligands by the condensation of amines and aldehydes often requires multiple steps, thus further streamlining the process is needed. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the first object of the present invention is to provide an imine bidentate ligand for scavenging metal ions, wherein the imine bidentate ligand for scavenging metal ions has a high scavenging rate for metal ions.

[0006] In order to overcome the shortcomings of the prior art, the second object of the present invention is to provide a method for preparing an imine bidentate ligand for removing metal ions. The preparation method is a one-step synthesis method, the synthesis method is simple, and it is convenient for large-scale production. The prepared imine bidentate ligand has a high scavenging rate for metal ions.

[0007] The third object of the present invention is to provide an application of an imine bidentate ligand for removing metal ions.

[0008] The fourth object of the present invention is to provide a method for preparing the metal complex.

[0009] A fifth object of the present invention is to provide a metal complex.

[0010] The sixth object of the present invention is to provide an application of the metal complex.

[0011] In order to achieve the first object of the above invention, the technical solution adopted by the present invention is as follows:

[0012] The present invention provides an imine bidentate ligand for removing metal ions, wherein the ligand is a compound having a structure shown in Formula I;

[0013]

[0014] In order to achieve the second purpose of the above invention, the technical solution adopted by the present invention is as follows:

[0015] The present invention provides a preparation method of an imine bidentate ligand for removing metal ions, comprising the following steps: mixing p-phenylenediamine and 2-thiophenecarboxaldehyde in a reaction solvent, performing a reflux reaction, and then performing suction filtration, washing, and drying to obtain the imine bidentate ligand for removing metal ions.

[0016] Furthermore, the molar ratio of p-phenylenediamine to 2-thiophenecarboxaldehyde is 1:2;

[0017] The reaction solvent includes a solvent and a catalyst; and / or

[0018] The solvent is water, and the catalyst is anhydrous ethanol; and / or

[0019] The volume ratio of water to anhydrous ethanol is (3-5):1; and / or

[0020] The mass volume ratio of the p-phenylenediamine to anhydrous ethanol is (100-120) mg: (8-12) mL.

[0021] Furthermore, the temperature of the reflux reaction is 76° C. to 80° C.; the time of the reflux reaction is 6 h to 9 h; and / or

[0022] Collect the precipitate by suction filtration and wash the precipitate with anhydrous ethanol; and / or

[0023] The drying is carried out in a vacuum drying oven at 38° C. to 42° C. for 22 h to 24 h.

[0024] In order to achieve the third purpose of the above invention, the technical solution adopted by the present invention is as follows:

[0025] The present invention provides an application of an imine bidentate ligand for removing metal ions, and an application of the imine bidentate ligand for removing metal ions in repairing a polluted environment or treating wastewater.

[0026] In order to achieve the fourth object of the above invention, the technical solution adopted by the present invention is as follows:

[0027] The present invention provides a method for preparing a metal complex. The method comprises mixing the above-mentioned imine bidentate ligand for scavenging metal ions or the imine bidentate ligand obtained by the above-mentioned method for preparing an imine bidentate ligand for scavenging metal ions with a metal ion solution, stirring the mixture at room temperature, and filtering to obtain a solid precipitate, which is the metal complex.

[0028] The present invention forms a metal complex by coordinating the imine-type bidentate ligand with the metal ion through head-to-tail crosslinking. The imine-type bidentate ligand contains both hard coordinating atoms (nitrogen atoms) and soft coordinating atoms (sulfur atoms). Through the synergistic effect of the hard coordinating nitrogen and soft coordinating sulfur atoms, it can chelate with most metal ions. Therefore, the imine-type bidentate ligand prepared by the present invention can be used to remove most metal ions.

[0029] Furthermore, the molar ratio of the imine bidentate ligand to the metal ion is 1:1; and / or

[0030] The metal ion solution is a metal salt solution; and / or

[0031] The metal ions include Cu 2+ 、Fe 3+ 、Ni 2+ 、Co 2+ or Pb 2+ At least one of .

[0032] Furthermore, the stirring time at room temperature is 12 h to 24 h.

[0033] In order to achieve the fifth purpose of the above invention, the technical solution adopted by the present invention is as follows:

[0034] The present invention provides a metal complex prepared by the above-mentioned method for preparing a metal complex.

[0035] In order to achieve the sixth object of the above invention, the technical solution adopted by the present invention is as follows:

[0036] The present invention provides an application of a metal complex, and an application of the metal complex described above or a metal complex prepared by the method for preparing the metal complex described above in photothermal conversion.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The present invention provides an imine bidentate ligand for removing metal ions, which has the ability to remove most metal ions, such as Cu 2+ 、Fe 3+ 、Ni 2+ 、Co 2+ , Pb 2+ Plasma, and the imine bidentate ligand has a high scavenging rate for metal ions, especially for Cu 2+ 、Co 2+ , Pb 2+ The clearance rate is as high as 99.9%. 3+ The clearance rate is as high as 99.3%. 2+ The clearance rate is as high as 98.78%.

[0039] (2) The present invention provides a method for preparing an imine bidentate ligand for removing metal ions. The imine bidentate ligand is prepared by a one-step synthesis method. The synthesis method is simple and convenient for large-scale production. The raw materials are cheap and the preparation cost is low. In addition, the prepared imine bidentate ligand has a high scavenging rate for metal ions.

[0040] (3) The application of the imine bidentate ligand for removing metal ions of the present invention has low operating costs, high efficiency in removing metal ions, and strong potential, and therefore has good application prospects.

[0041] (4) The present invention provides a method for preparing a metal complex, wherein the metal complex is prepared by mixing an imine-type bidentate ligand with a metal ion solution, stirring and filtering at room temperature. The method has the characteristics of simple preparation method, mild preparation conditions, low preparation cost, and large-scale production.

[0042] (5) The application of a metal complex of the present invention has a good application prospect in photothermal conversion because the metal complex has excellent photothermal performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1 This is the LC-MS graph of the imine bidentate ligand prepared in Example 1 of the present invention.

[0045] Figure 2 It is a molecular structure diagram of the metal complex of Example 7 of the present invention.

[0046] Figure 3 The concentrations of pbtpm and Cu in Example 7 of the present invention are different. 2+ Before stirring, after stirring, after filtration, and Cu 2+ The color phenomenon.

[0047] Figure 4 The concentrations of pbtpm and Cu at 5mM and 20mM in Example 7 of the present invention are 2+ ICP-MS comparison of the cleaning effect after stirring.

[0048] Figure 5 The concentrations of pbtpm and Fe in Example 8 of the present invention are different. 3+ Before stirring, after stirring, after filtration, and Fe 3+ The color phenomenon.

[0049] Figure 6 The concentrations of pbtpm and Fe at 5mM and 20mM in Example 8 of the present invention are 3+ ICP-MS comparison of the cleaning effect after stirring.

[0050] Figure 7 The concentrations of Pbtpm and Pb in Example 9 of the present invention are different. 2+ Before stirring, after stirring, filtrate after filtration, and Pb before and after stirring 2+ The color phenomenon.

[0051] Figure 8 The concentrations of pbtpm and Pb at 5mM and 20mM in Example 9 of the present invention are 2+ ICP-MS comparison of the cleaning effect after stirring.

[0052] Figure 9 The concentrations of pbtpm and Ni in Example 10 of the present invention are different. 2+ Ni before stirring, after stirring, filtrate after filtration, and before and after stirring 2+The color phenomenon.

[0053] Figure 10 The concentrations of pbtpm and Ni at 5mM and 20mM in Example 9 of the present invention are 2+ ICP-MS comparison of the cleaning effect after stirring.

[0054] Figure 11 The concentrations of pbtpm and Co in Example 10 of the present invention are different. 2+ Before stirring, after stirring, after filtration, and Co 2+ The color phenomenon.

[0055] Figure 12 The concentrations of pbtpm and Co at 5mM and 20mM in Example 9 of the present invention are 2+ ICP-MS comparison of the cleaning effect after stirring.

[0056] Figure 13 is the pbtpm-Cu in Example 12 of the present invention 2+ A graph showing temperature variation over time at different laser powers.

[0057] Figure 14 is the pbtpm-Cu in Example 12 of the present invention 2+ At 2W / cm 2 Temperature versus time curve for six cycles at the same power density.

[0058] Figure 15 is the pbtpm-Cu in Example 12 of the present invention 2+ Thermal image of .

[0059] Figure 16 is the pbtpm-Fe in Example 12 of the present invention 3+ A graph showing temperature variation over time at different laser powers.

[0060] Figure 17 is the pbtpm-Fe in Example 12 of the present invention 3+ At 2W / cm 2 Temperature versus time curve for six cycles at the same power density.

[0061] Figure 18 is the pbtpm-Fe in Example 12 of the present invention 3+ Thermal image of .

[0062] Figure 19 is pbtpm-Pb in Example 12 of the present invention 2+ A graph showing temperature variation over time at different laser powers.

[0063] Figure 20 is pbtpm-Pb in Example 12 of the present invention 2+ At 2W / cm 2 Temperature versus time curve for six cycles at the same power density.

[0064] Figure 21 is pbtpm-Pb in Example 12 of the present invention 2+ Thermal image of .

[0065] Figure 22 is the pbtpm-Ni in Example 12 of the present invention 2+ A graph showing temperature variation over time at different laser powers.

[0066] Figure 23 is the pbtpm-Ni in Example 12 of the present invention 2+ At 2W / cm 2 Temperature versus time curve for six cycles at the same power density.

[0067] Figure 24 is the pbtpm-Ni in Example 12 of the present invention 2+ Thermal image of .

[0068] Figure 25 is the pbtpm-Co in Example 12 of the present invention 2+ A graph showing temperature variation over time at different laser powers.

[0069] Figure 26 is the pbtpm-Co in Example 12 of the present invention 2+ At 2W / cm 2 Temperature versus time curve for six cycles at the same power density.

[0070] Figure 27 is the pbtpm-Co in Example 12 of the present invention 2+ Thermal image of .

[0071] Figure 28 The pbtpm-Cu of Example 7 2+ SEM image of .

[0072] Figure 29 The pbtpm-Fe of Example 8 3+ SEM image of .

[0073] Figure 30 is the pbtpm-Co of Example 11 2+ SEM image of .

[0074] Figure 31 The pbtpm-Ni of Example 10 2+SEM image of .

[0075] Figure 32 is the pbtpm-Pb of Example 9 2+ SEM image of . DETAILED DESCRIPTION

[0076] In order to make the technical problems, technical solutions and beneficial effects to be solved by 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 intended to limit the present invention.

[0077] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. In the present invention, the singular forms "a", "an", "the" and "the" used in the embodiments and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0078] In an embodiment of the present invention, an imine-based bidentate ligand for removing metal ions is provided, wherein the ligand is a compound having a structure shown in Formula I;

[0079]

[0080] In an embodiment of the present invention, a method for preparing an imine-based bidentate ligand for removing metal ions comprises the following steps: mixing p-phenylenediamine and 2-thiophenecarboxaldehyde in a reaction solvent, performing a reflux reaction, and then filtering, washing, and drying to obtain the imine-based bidentate ligand for removing metal ions.

[0081] In some embodiments, the molar ratio of p-phenylenediamine to 2-thiophenecarboxaldehyde is 1:2;

[0082] The reaction solvent includes a solvent and a catalyst; and / or

[0083] The solvent is water, and the catalyst is anhydrous ethanol; and / or

[0084] The volume ratio of water to anhydrous ethanol is (3-5):1; and / or

[0085] The mass volume ratio of the p-phenylenediamine to anhydrous ethanol is (100-120) mg: (8-12) mL.

[0086] In some embodiments, the reflux reaction temperature is 76° C. to 80° C.; the reflux reaction time is 6 h to 9 h; and / or

[0087] Collect the precipitate by suction filtration and wash the precipitate with anhydrous ethanol; and / or

[0088] The drying is carried out in a vacuum drying oven at 38° C. to 42° C. for 22 h to 24 h.

[0089] In an embodiment of the present invention, the imine bidentate ligand for removing metal ions is used in repairing a polluted environment or treating wastewater.

[0090] In an embodiment of the present invention, a method for preparing a metal complex comprises mixing the above-described imine bidentate ligand for scavenging metal ions or the imine bidentate ligand obtained by the above-described method for preparing an imine bidentate ligand for scavenging metal ions with a metal ion solution, stirring the mixture at room temperature, and filtering to obtain a solid precipitate, which is the metal complex.

[0091] In some embodiments, the molar ratio of the imine bidentate ligand to the metal ion is 1:1; and / or

[0092] The metal ion solution is a metal salt solution; and / or

[0093] The metal ions include Cu 2+ 、Fe 3+ 、Ni 2+ 、Co 2+ , or Pb 2+ At least one of .

[0094] In some embodiments, the stirring time at room temperature is 12 h to 24 h.

[0095] In an embodiment of the present invention, a metal complex is prepared by the above-mentioned method for preparing a metal complex.

[0096] In an embodiment of the present invention, an application of a metal complex, an application of the metal complex described above or a metal complex prepared by the method for preparing the metal complex described above in photothermal conversion.

[0097] The following describes the details in conjunction with specific embodiments.

[0098] Example 1

[0099] An imine bidentate ligand for removing metal ions, wherein the ligand is a compound having a structure shown in Formula I:

[0100]

[0101] The preparation method of this metal ion scavenging imine bidentate ligand comprises the following steps: p-phenylenediamine and 2-thiophenecarboxaldehyde are mixed in a reaction solvent, refluxed at 78°C for 8 hours to produce a large amount of yellow precipitate, then filtered to collect the precipitate, washed with anhydrous ethanol, and then dried in a vacuum drying oven at 40°C for 24 hours to obtain the metal ion scavenging imine bidentate ligand (denoted as pbtpm) as a bright yellow solid. The molar ratio of p-phenylenediamine to 2-thiophenecarboxaldehyde is 1:2. In this embodiment, the reaction solvent is a mixture of water and anhydrous ethanol, with a volume ratio of water to anhydrous ethanol of 4:1. In this embodiment, the mass volume ratio of p-phenylenediamine to anhydrous ethanol is 108 mg:10 mL.

[0102] The yield of the imine bidentate ligand prepared in this example is 79.8%, and the detection results are as follows: Figure 1 As shown. Figure 1 It can be seen that there is a peak at 296, which is consistent with the molecular weight of the imine bidentate ligand, thus proving that the imine bidentate ligand (pbtpm) can be prepared by the preparation method of the imine bidentate ligand for scavenging metal ions of the present invention.

[0103] Example 2

[0104] A method for preparing an imine-based bidentate ligand for scavenging metal ions comprises the following steps: mixing p-phenylenediamine and 2-thiophenecarboxaldehyde in a reaction solvent, subjecting the mixture to a reflux reaction at 76°C for 9 hours to produce a large amount of yellow precipitate, collecting the precipitate by suction filtration, washing the precipitate with anhydrous ethanol, and then drying it in a vacuum drying oven at 38°C for 24 hours to obtain the imine-based bidentate ligand for scavenging metal ions (denoted as pbtpm) as a bright yellow solid. The molar ratio of p-phenylenediamine to 2-thiophenecarboxaldehyde is 1:2. In this embodiment, the reaction solvent is a mixture of water and anhydrous ethanol, with a volume ratio of water to anhydrous ethanol of 3:1. In this embodiment, the mass-to-volume ratio of p-phenylenediamine to anhydrous ethanol is 100 mg:8 mL.

[0105] Example 3

[0106] A method for preparing an imine-based bidentate ligand for scavenging metal ions comprises the following steps: mixing p-phenylenediamine and 2-thiophenecarboxaldehyde in a reaction solvent, subjecting the mixture to a reflux reaction at 80°C for 6 hours to produce a large amount of yellow precipitate, collecting the precipitate by suction filtration, washing the precipitate with anhydrous ethanol, and then drying it in a vacuum drying oven at 42°C for 22 hours to obtain the imine-based bidentate ligand for scavenging metal ions (denoted as pbtpm) as a bright yellow solid. The molar ratio of p-phenylenediamine to 2-thiophenecarboxaldehyde is 1:2. In this embodiment, the reaction solvent is a mixture of water and anhydrous ethanol, with a volume ratio of water to anhydrous ethanol of 5:1. In this embodiment, the mass-to-volume ratio of p-phenylenediamine to anhydrous ethanol is 120 mg:12 mL.

[0107] Example 4

[0108] A method for preparing an imine-based bidentate ligand for scavenging metal ions comprises the following steps: mixing p-phenylenediamine and 2-thiophenecarboxaldehyde in a reaction solvent, subjecting the mixture to reflux reaction at 77°C for 7 hours to produce a large amount of yellow precipitate, collecting the precipitate by suction filtration, washing the precipitate with anhydrous ethanol, and then drying it in a vacuum drying oven at 39°C for 23 hours to obtain the imine-based bidentate ligand for scavenging metal ions (denoted as pbtpm) as a bright yellow solid. The molar ratio of p-phenylenediamine to 2-thiophenecarboxaldehyde is 1:2. In this embodiment, the reaction solvent is a mixture of water and anhydrous ethanol, with a volume ratio of water to anhydrous ethanol of 3.5:1. In this embodiment, the mass-to-volume ratio of p-phenylenediamine to anhydrous ethanol is 110 mg:9 mL.

[0109] Example 5

[0110] A method for preparing an imine-based bidentate ligand for scavenging metal ions comprises the following steps: mixing p-phenylenediamine and 2-thiophenecarboxaldehyde in a reaction solvent, subjecting the mixture to a reflux reaction at 79°C for 6.5 hours to produce a large amount of yellow precipitate. The precipitate is then collected by filtration, washed with anhydrous ethanol, and dried in a vacuum drying oven at 41°C for 22.5 hours to obtain the imine-based bidentate ligand for scavenging metal ions (denoted as pbtpm) as a bright yellow solid. The molar ratio of p-phenylenediamine to 2-thiophenecarboxaldehyde is 1:2. In this embodiment, the reaction solvent is a mixture of water and anhydrous ethanol, with a volume ratio of water to anhydrous ethanol of 4.5:1. In this embodiment, the mass-to-volume ratio of p-phenylenediamine to anhydrous ethanol is 115 mg:11 mL.

[0111] Example 6

[0112] Application of the imine bidentate ligand prepared in Examples 1 to 5 for removing metal ions, and application of the prepared imine bidentate ligand for removing metal ions in repairing a contaminated environment or treating wastewater.

[0113] Example 7

[0114] A method for preparing a metal complex comprises adding an imine bidentate ligand for removing metal ions and CuCl2·2H2O in Example 1 to an ethanol aqueous solution and mixing them, wherein the imine bidentate ligand and CuCl2·2H2O are mixed. 2+ The molar ratio of ethanol to water is 1:1, and the volume ratio of anhydrous ethanol to water in the ethanol aqueous solution is 1:4. The mixture is stirred at room temperature for 16 hours, and the solid precipitate is obtained by filtration, which is the metal complex (denoted as pbtpm-Cu 2+ ).

[0115] Among them, the molecular structure of the metal complex is shown in the figure below: Figure 2 shown. Figure 2 In the formula ( ), M represents a metal atom. Imine-type bidentate ligands chelate metal ions to form metal complexes through the cooperation of hard-coordinating nitrogen atoms and soft-coordinating sulfur atoms.

[0116] In this embodiment, the imine bidentate ligand and Cu 2+ Different concentration gradients were set to observe the removal of Cu by imine bidentate ligand (pbtpm) under different concentration conditions. 2+ Among them, the imine bidentate ligand and Cu 2+ The molar concentration gradient was set to 1mM, 2mM, 5mM, 10mM, and 20mM. The detection method was as follows: different concentrations of Cu 2+ After the solution was developed with ammonia water, an imine bidentate ligand (i.e., L1) was added, and then stirred at room temperature for 16 hours. The filtrate was filtered and the reaction between the imine bidentate ligand and Cu at different concentrations was observed. 2+ The results of the filtrate before stirring, after stirring and after filtration are as follows: Figure 3 shown.

[0117] Depend on Figure 3 It can be seen that by comparing the amine bidentate ligand (pbtpm) with Cu 2+ Ion coloration phenomenon before and after stirring. PBTP successfully removed most of the Cu in the solution. 2+ , add Cu 2+ The color developer ammonia water will not show blue. Figure 4 As shown ( Figure 4 The horizontal axis "concentraion" is the concentration, and the vertical axis "Normalized ion content" is the positive charge ion content). 2+ The samples were tested by ICP-MS. The results showed that after adding 5mM concentration of pbtpm and stirring, Cu 2+ The clearance rate reached 99.927%. After adding 20mM Cu 2+The removal rate reached 99.947%. Therefore, it shows that the imine bidentate ligand prepared by the present invention has a good effect on Cu 2+ It has the advantages of high removal rate and excellent removal effect.

[0118] Example 8

[0119] A method for preparing a metal complex. The difference between this embodiment and embodiment 7 is that the metal ion removed is Fe 3+ , Fe 3+ The color was developed with potassium thiocyanate and stirred at room temperature for 12 hours. The rest of the preparation method, concentration gradient and detection method were the same as in Example 7. 3+ The results of the filtrate before stirring, after stirring and after filtration are as follows: Figure 5 The metal complex prepared in this example is denoted as pbtpm-Fe 3+ .

[0120] Depend on Figure 5 It can be seen that by comparing the amine bidentate ligand (pbtpm) with Fe 3+ Ion coloration phenomenon before and after stirring. PBTP successfully removed most of the Fe in the solution. 3+ , add Fe to the filtrate 3+ The color developer potassium thiocyanate will not show red. Figure 6 As shown ( Figure 6 The horizontal axis "concentraion" is the concentration, and the vertical axis "Normalized ion content" is the positive charge ion content). 3+ The samples were tested by ICP-MS. The results showed that after adding 5mM concentration of pbtpm and stirring, Fe 3+ The clearance rate reached 99.307%. After adding 20mM Fe 3+ The clearance rate reached 98.994%. Therefore, it shows that the imine bidentate ligand prepared by the present invention has an excellent effect on Fe 3+ It has the advantages of high removal rate and excellent removal effect.

[0121] Example 9

[0122] A method for preparing a metal complex. The difference between this embodiment and embodiment 7 is that the metal ion removed is Pb 2+ , Pb 2+ The color was developed with potassium iodide and stirred at room temperature for 24 hours. The rest of the preparation method, concentration gradient and detection method were the same as in Example 7. 2+ The results of the filtrate before stirring, after stirring and after filtration are as follows: Figure 7The metal complex prepared in this example is denoted as pbtpm-Pb 2+ .

[0123] Depend on Figure 7 It can be seen that by comparing the amine bidentate ligand (pbtpm) with Pb 2+ Ion coloration phenomenon before and after stirring. Pbtpm successfully removed most of the Pb in the solution. 2+ , add Pb to the filtrate 2+ The color developer potassium iodide no longer produces golden yellow substance. Figure 8 As shown ( Figure 8 The horizontal axis "concentraion" is the concentration, and the vertical axis "Normalized ion content" is the positive charge ion content), which will remove Pb 2+ The samples were tested by ICP-MS. The results showed that after adding 5mM concentration of pbtpm and stirring, Pb 2+ The clearance rate reached 99.996%. After adding 20mM Pb 2+ The removal rate reached 99.995%. Therefore, it shows that the imine bidentate ligand prepared by the present invention has a good effect on Pb 2+ It has the advantages of high removal rate and excellent removal effect.

[0124] Example 10

[0125] A method for preparing a metal complex. The difference between this embodiment and embodiment 7 is that the metal ion removed is Ni 2+ , Ni 2+ The color was developed with dimethylglyoxime and stirred at room temperature for 24 hours. The rest of the preparation method, concentration gradient and detection method were the same as in Example 7. 2+ The results of the filtrate before stirring, after stirring and after filtration are as follows: Figure 9 The metal complex prepared in this embodiment is denoted as pbtpm-Ni 2+ .

[0126] Depend on Figure 9 It can be seen that by comparing the amine bidentate ligand (pbtpm) with Ni 2+ Ion coloration phenomenon before and after stirring. PBTP successfully removed most of the Ni in the solution. 2+ , Ni was added to the filtrate 2+ After adding the color developing agent dimethylglyoxime, the pink color no longer appears. Figure 10 As shown ( Figure 10 The horizontal axis "concentraion" is the concentration, and the vertical axis "Normalizedioncontent" is the positive charge ion content), which will remove Ni2+ The samples were tested by ICP-MS. The results showed that after adding 5mM concentration of pbtpm and stirring, Ni 2+ The clearance rate reached 92.590%. After adding 20mM Ni 2+ The removal rate reached 98.781%. Therefore, it shows that the imine bidentate ligand prepared by the present invention has a good effect on Ni 2+ It has the advantages of high removal rate and excellent removal effect.

[0127] Example 11

[0128] A method for preparing a metal complex. The difference between this embodiment and embodiment 7 is that the metal ion removed is Co 2+ ,Co 2+ The color was developed with ammonia water and stirred at room temperature for 24 hours. The rest of the preparation method, concentration gradient and detection method were the same as in Example 7. 2+ The results of the filtrate before stirring, after stirring and after filtration are as follows: Figure 11 The metal complex prepared in this example is denoted as pbtpm-Co 2+ .

[0129] Depend on Figure 11 It can be seen that by comparing the amine bidentate ligand (pbtpm) with Co 2+ Ion coloration phenomenon before and after stirring. PBTP successfully removed most of the Co in the solution. 2+ , add Co to the filtrate 2+ After adding ammonia water as the color developer, the green color becomes much lighter. Figure 12 As shown ( Figure 12 The horizontal axis "concentraion" is the concentration, and the vertical axis "Normalizedion content" is the positive charge ion content), which will remove Co 2+ The samples were subjected to ICP-MS detection, and the results showed that after adding 5mM concentration of pbtpm and stirring, Co 2+ The clearance rate reached 98.020%. After adding 20mM Co 2+ The removal rate reached 99.986%. Therefore, it shows that the imine bidentate ligand prepared by the present invention has a good effect on Co 2+ It has the advantages of high removal rate and excellent removal effect.

[0130] Example 12

[0131] Application of a metal complex, application of a metal complex prepared in Examples 7 to 11 in photothermal conversion.

[0132] The precipitates generated by the chelation of Pbtpm with various metal ions in Examples 7 to 11 were filtered out and collected, and the solid precipitates were irradiated with an 808 nm laser. The laser was turned off after 90 seconds of irradiation, for a total of 2 minutes. The temperature of the solid precipitate was monitored and recorded in real time using an infrared thermal imager.

[0133] The pbtpm-Cu prepared in Examples 7 to 11 above 2+ 、pbtpm-Fe 3+ 、pbtpm-Pb 2+ 、pbtpm-Ni 2 + 、pbtpm-Co 2+ The temperature changes with time under different laser powers were detected. 2 Temperature variation over time of the metal complex after six cycles under power density, as well as the photothermal conditions of the metal complex.

[0134] Among them, pbtpm-Cu 2+ The temperature changes with time at different laser powers, such as Figure 13 As shown. At 2W / cm 2 Under power density, pbtpm-Cu 2+ The temperature variation curve of six cycles is as follows: Figure 14 As shown. pbtpm-Cu 2+ The thermal image of Figure 15 As shown. Figure 13 and Figure 14 It can be seen that at 2W / cm 2 Under the laser power density, pbtpm-Cu 2+ It reaches 200℃ in about 5s, indicating that pbtpm-Cu 2+ It has excellent light and heat performance.

[0135] Among them, pbtpm-Fe 3+ The temperature changes with time at different laser powers, such as Figure 16 As shown. At 2W / cm 2 Under power density, pbtpm-Fe 3+ The temperature variation curve of six cycles is as follows: Figure 17 As shown. pbtpm-Fe 3+ The thermal image of Figure 18 As shown. Figure 16 and Figure 17 It can be seen that at 2W / cm 2 Under the laser power density, pbtpm-Fe 3+It reaches about 110℃ in about 5s, indicating that pbtpm-Fe 3+ It has excellent light and heat performance.

[0136] Among them, pbtpm-Pb 2+ The temperature changes with time at different laser powers, such as Figure 19 As shown. At 2W / cm 2 Under power density, pbtpm-Pb 2+ The temperature variation curve of six cycles is as follows: Figure 20 As shown. pbtpm-Pb 2+ The thermal image of Figure 21 As shown. Figure 19 and Figure 20 It can be seen that at 2W / cm 2 Under the laser power density, pbtpm-Pb 2+ It reaches about 53℃ in about 5s, indicating that pbtpm-Pb 2+ It has good light and heat performance.

[0137] Among them, pbtpm-Ni 2+ The temperature changes with time at different laser powers, such as Figure 22 As shown. At 2W / cm 2 At power density, pbtpm-Ni 2+ The temperature variation curve of six cycles is as follows: Figure 23 As shown. pbtpm-Ni 2+ The thermal image of Figure 24 As shown. Figure 22 and Figure 23 It can be seen that at 2W / cm 2 Under the laser power density, pbtpm-Ni 2+ It reaches about 60℃ in about 5s, indicating that pbtpm-Ni 2+ It has good light and heat performance.

[0138] Among them, pbtpm-Co 2+ The temperature changes with time at different laser powers, such as Figure 25 As shown. At 2W / cm 2 At power density, pbtpm-Co 2+ The temperature variation curve of six cycles is as follows: Figure 26 As shown. pbtpm-Co 2+ The thermal image of Figure 27 As shown. Figure 25 and Figure 26 It can be seen that at 2W / cm 2Under the laser power density, pbtpm-Co 2+ It reaches about 60℃ in about 5s, indicating that pbtpm-Co 2+ It has good light and heat performance.

[0139] The above test results show that the metal complex prepared in the present invention has excellent photothermal performance and has good application prospects in photothermal conversion.

[0140] Structural morphology characterization

[0141] The metal complexes pbtpm-Cu prepared in Examples 7 to 11 were 2+ 、pbtpm-Fe 3+ 、pbtpm-Pb 2 + 、pbtpm-Ni 2+ 、pbtpm-Co 2+ Scanning electron microscopy (SEM) was used to characterize the morphology of the samples.

[0142] Among them, pbtpm-Cu 2+ SEM images of Figure 28 As shown. Figure 28 It can be seen that pbtpm-Cu 2+ It presents a regular layered stacking structure and is evenly distributed.

[0143] Among them pbtpm-Fe 3+ SEM images of Figure 29 As shown. Figure 29 It can be seen that pbtpm-Fe 3+ It presents a regular lamellar stacking structure and is evenly distributed.

[0144] Among them pbtpm-Co 2+ SEM images of Figure 30 As shown. Figure 30 Visible pbtpm-Co 2+ It presents a regular layered stacking structure and is evenly distributed.

[0145] Among them pbtpm-Ni 2+ SEM images of Figure 31 As shown. Figure 31 Visible pbtpm-Ni 2+ It presents an irregular layered stacking structure and is evenly distributed.

[0146] Among them pbtpm-Pb 2+ SEM images of Figure 32 As shown. Figure 32 Visible pbtpm-Pb 2+It presents a regular micro-spherical stacking structure with different sizes but uniform distribution.

[0147] It can be seen from this that when the imine bidentate ligand (pbtpm) coordinates with different metal ions, the morphology of the coordination polymer, that is, the prepared metal complex, may be very different.

[0148] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. An imine bidentate ligand for removing metal ions, characterized in that: The ligand is a compound having a structure shown in Formula I; 2. The method for preparing an imine bidentate ligand for removing metal ions according to claim 1, characterized in that: The following steps are involved: The p-phenylenediamine and 2-thiophenecarboxaldehyde are mixed in a reaction solvent, subjected to reflux reaction, and then filtered, washed, and dried to obtain the imine bidentate ligand for removing metal ions.

3. The method for preparing an imine bidentate ligand for removing metal ions according to claim 2, wherein: The molar ratio of p-phenylenediamine to 2-thiophenecarboxaldehyde is 1:2; The reaction solvent includes a solvent and a catalyst; and / or The solvent is water, and the catalyst is anhydrous ethanol; and / or The volume ratio of water to anhydrous ethanol is (3-5):1; and / or The mass volume ratio of the p-phenylenediamine to anhydrous ethanol is (100-120) mg: (8-12) mL.

4. The method for preparing an imine bidentate ligand for removing metal ions according to claim 2, wherein: The reflux reaction temperature is 76°C to 80°C; the reflux reaction time is 6h to 9h; and / or Collect the precipitate by suction filtration and wash the precipitate with anhydrous ethanol; and / or The drying is carried out in a vacuum drying oven at 38° C. to 42° C. for 22 h to 24 h.

5. The use of an imine bidentate ligand for removing metal ions according to claim 1, characterized in that: The application of the imine bidentate ligand for removing metal ions in repairing a polluted environment or treating wastewater.

6. A method for preparing a metal complex, characterized in that: The imine bidentate ligand for removing metal ions according to claim 1 or the imine bidentate ligand prepared by the preparation method of the imine bidentate ligand for removing metal ions according to any one of claims 2 to 4 is mixed with a metal ion solution, stirred at room temperature, and filtered to obtain a solid precipitate, which is the metal complex.

7. The method for preparing a metal complex according to claim 6, wherein: The molar ratio of the imine bidentate ligand to the metal ion is 1:1; and / or The metal ion solution is a metal salt solution; and / or The metal ions include Cu 2+ 、Fe 3+ 、Ni 2+ 、Co 2+ or Pb 2+ At least one of .

8. The method for preparing a metal complex according to claim 6, wherein: The stirring time at room temperature is 12 h to 24 h.

9. A metal complex, characterized in that The metal complex is prepared by the preparation method of any one of claims 6 to 8.

10. An application of a metal complex, characterized in that: Use of a metal complex according to claim 9 or a metal complex prepared by the preparation method of a metal complex according to any one of claims 6 to 8 in photothermal conversion.

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