Metal-organic adsorbent, its preparation method and application

Abstract

This invention relates to a metal-organic adsorbent, its preparation method, and its application, belonging to the field of composite material technology. The invention utilizes the condensation reaction of terephthalaldehyde and aminothiourea, followed by the incorporation of 3-formyl-4-hydroxybenzoic acid to form an organic ligand. This organic ligand is then combined with ZrCl4 to prepare a metal-organic adsorbent. The metal-organic adsorbent can be used for targeted removal of copper ions from solution. The adsorption rate of copper ions by the metal-organic adsorbent can reach 98.5%, and after five repetitions, the adsorption rate can still reach 89.71%.

Description

Technical Field

[0001] This invention relates to a metal-organic adsorbent, its preparation method and application, belonging to the field of composite material technology. Background Technology

[0002] Copper, a common heavy metal, is difficult to degrade and migrate, easily accumulating in arable land and soil, and ultimately entering the human food chain, causing significant harm to human health. It has been listed as one of the priority environmental pollutants for control. Copper possesses excellent electrical and thermal conductivity, ductility, corrosion resistance, and wear resistance, and can form alloys with other metals with diverse properties. It is widely used in electrical, light industry, machinery manufacturing, construction, and defense industries. However, with the widespread use of copper, the resulting copper pollution problem is becoming increasingly serious.

[0003] Many researchers have been searching for effective methods to remove copper(II) ions from water. Currently, the main methods for treating copper ion wastewater include adsorption, reverse osmosis, electrocoagulation, ion exchange, and chemical precipitation coagulation. Reverse osmosis requires high-pressure equipment, and the raw water utilization rate is only 75-80%. The membrane needs regular cleaning. Ion exchange may cause secondary pollution, and the exchanged ions require secondary removal, making it difficult. Electrocoagulation requires high energy consumption and is economically inefficient. Chemical precipitation can lead to secondary pollution of water and soil, and the removal effect is difficult to stabilize, with complex subsequent treatment.

[0004] Currently, various adsorbents such as activated carbon, biomaterials, and resins are widely used. However, traditional adsorbents have many drawbacks, such as low adsorption capacity, selectivity, and repeatability. Activated carbon exhibits low adsorption selectivity, while bioadsorbents suffer from poor stability and low adsorption capacity. Summary of the Invention

[0005] This invention addresses the problems of poor selectivity and structural stability of existing adsorbents for adsorbing copper(II) ions by proposing a metal-organic adsorbent, its preparation method, and its application. The method utilizes the condensation reaction of terephthalaldehyde and aminothiourea, followed by the incorporation of 3-formyl-4-hydroxybenzoic acid to form an organic ligand. This organic ligand is then combined with ZrCl4 to prepare the metal-organic adsorbent. The metal-organic adsorbent can be used for targeted removal of copper ions from solution. The adsorption rate of copper ions by the metal-organic adsorbent can reach 98.5%, and even after five repetitions, the adsorption rate can still reach 89.71%.

[0006] A metal-organic adsorbent is prepared by condensing terephthalaldehyde and aminothiourea, followed by incorporation into 3-formyl-4-hydroxybenzoic acid to form an organic ligand. The organic ligand is then combined with ZrCl4 to prepare the metal-organic adsorbent. Its structural formula is as follows:

[0007]

[0008] The specific steps for preparing the metal-organic adsorbent are as follows:

[0009] (1) Terephthalaldehyde and aminothiourea were added to methanol solvent and stirred to dissolve, resulting in solution A. Glacial acetic acid was added to solution A as a catalyst, and the reaction was stirred at 60-65℃ for 12-24 h. After cooling to room temperature, the solid and liquid were separated, and the terephthalaldehyde diaminothiourea was recrystallized in methanol and dried under vacuum. The reaction equation is as follows:

[0010]

[0011] (2) Vacuum-dried terephthalaldehyde diaminothiourea and 3-formyl-4-hydroxybenzoic acid were ultrasonically dissolved in an ethanol-DMF mixed solution. The mixture was stirred at 60-65℃ for 12-24 h. Zirconium tetrachloride was then added, and the temperature was raised to 125-135℃ and stirred for 48-72 h. After cooling to room temperature, the solid and liquid were separated. The solid was washed, soaked, and vacuum dried to obtain the metal-organic adsorbent. The reaction equation is as follows:

[0012]

[0013] In step (1), the molar ratio of terephthalaldehyde to aminothiourea is 1:0.5-1.

[0014] The molar concentration of terephthalaldehyde in solution A in step (1) is 0.1 to 0.5 mmol / mL.

[0015] In step (1), the volume ratio of the catalyst glacial acetic acid to solution A is 0.5 to 1:50.

[0016] In step (2), the molar ratio of terephthalaldehyde diaminothiourea and 3-formyl-4-hydroxybenzoic acid is 1:0.8 to 1.2.

[0017] In step (2), the volume ratio of ethanol to DMF in the ethanol-DMF mixed solution is 1:3 to 4.

[0018] In step (2), the total mass ratio of terephthalaldehyde diaminothiourea and 3-formyl-4-hydroxybenzoic acid to zirconium tetrachloride is 1-2:1.

[0019] The metal-organic adsorbent is used for targeted adsorption of copper ions in solution.

[0020] The overall reaction equation is as follows:

[0021]

[0022] Mechanism of selective and efficient adsorption of copper(II) ions by organometallic adsorbents: The mechanism of interaction between the active functional groups of the adsorbent and Cu(II) was studied by XPS (see...) Figure 4 The total peak before and after adsorption showed three new doublets, Cu2p, after adsorption, indicating that Cu(II) was successfully captured by the organometallic adsorbent. The different binding modes of Cu(II) with the active functional groups of the organometallic adsorbent led to the division of the Cu2p peak into three doublets at 933.1 eV and 934.6 eV, 943.3 eV and 945.6 eV, and 952.2 eV and 953.9 eV. Before adsorption, the binding energy of the C=N bond in the adsorbent was 402. At 0.3 eV, a new peak of 407.2 eV appears after chelation with nitrogen-containing groups; the C=S peaks appear at 161.8 eV and 163.0 eV; due to the chelation of Cu(II) ions with sulfur-containing C=S groups, new S2p doublets appear at 168.9 eV and 170.2 eV; this proves the chelation effect of S on Cu(II) ions, thus determining that the adsorption mechanism of this adsorbent is the electrostatic interaction and chelation reaction between sulfur-containing functional groups, nitrogen-containing functional groups and Cu(II) ions.

[0023] The beneficial effects of this invention are:

[0024] (1) A metal-organic framework adsorbent with high selectivity and good reproducibility was synthesized by condensing terephthalaldehyde and aminothiourea and adding 3-formyl4-hydroxybenzoic acid. The metal-organic adsorbent can target and remove Cu(II) in coexisting ions.

[0025] (2) The organometallic adsorbent Zr-DACA of the present invention has a huge specific surface area, many reactive functional groups in the material, and is easy to modify; the organometallic adsorbent Zr-DACA has a permanently open pore structure.

[0026] (3) The adsorption rate of the metal-organic adsorbent Zr-DACA of the present invention can reach 98.5%, and after repeating 5 times, the selective adsorption rate of copper ions can also reach 89.71%. Attached Figure Description

[0027] Figure 1 Here is a SEM image of the organometallic adsorbent Zr-DACA from Example 1;

[0028] Figure 2 EDS diagram of the organometallic adsorbent Zr-DACA adsorbent in Example 1;

[0029] Figure 3 The XRD pattern of the organometallic adsorbent Zr-DACA in Example 1 is shown.

[0030] Figure 4The image shows XPS images of the Zr-DACA adsorbent before and after adsorption of copper ions in Example 1. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0032] Example 1: Preparation method of the organometallic adsorbent Zr-DACA, the specific steps are as follows:

[0033] (1) Terephthalaldehyde and aminothiourea were added to 50 mL of methanol solvent and stirred to dissolve, resulting in solution A. Glacial acetic acid was added to solution A as a catalyst, and the reaction was stirred at 60 °C for 24 h. After cooling to room temperature, the solid and liquid were separated, and terephthalaldehyde diaminothiourea was recrystallized in methanol and dried under vacuum at 65 °C. The molar ratio of terephthalaldehyde to aminothiourea was 1:0.5, the molar concentration of terephthalaldehyde in solution A was 0.2 mol / mL, and the volume ratio of glacial acetic acid to solution A was 0.5:50. The reaction equation is as follows:

[0034]

[0035] (2) Vacuum-dried terephthalaldehyde diaminothiourea and 3-formyl-4-hydroxybenzoic acid were ultrasonically dissolved in 50 mL of ethanol-DMF mixed solution. The mixture was stirred at 65 °C for 12 h, then zirconium tetrachloride was added, and the mixture was heated to 125 °C and stirred for 48 h. After cooling to room temperature, the solid and liquid were separated. The solid was washed, soaked, and vacuum dried to obtain the metal-organic adsorbent. The molar ratio of terephthalaldehyde diaminothiourea and 3-formyl-4-hydroxybenzoic acid was 1:0.8, the volume ratio of ethanol to DMF in the ethanol-DMF mixed solution was 1:3, and the mass ratio of the total mass of terephthalaldehyde diaminothiourea and 3-formyl-4-hydroxybenzoic acid to zirconium tetrachloride was 1:1. The reaction equation is as follows:

[0036]

[0037] The SEM, EDS, XRD, and XPS images of the organometallic adsorbent Zr-DACA in this embodiment are shown below. Figures 1-4The SEM-EDS images show that the surface of the organometallic adsorbent Zr-DACA is relatively smooth and composed of a stacked structure, mainly consisting of C, O, Zr, N, and S. The weight percentages of C, O, Zr, N, and S are 43.4%, 27.5%, 20.2%, 7.4%, and 1.5%, respectively. The XRD pattern shows it as an amorphous material, but a Zr peak is clearly observed around 10°. The post-reaction XPS image shows a Cu2p peak, confirming that the organometallic adsorbent Zr-DACA has successfully adsorbed Cu(II) ions. The XPS study investigated the mechanism of adsorption between the active functional groups of the adsorbent and Cu(II) ions, revealing the interaction between Cu(II) ions and the novel organometallic adsorbent. The binding of the active functional groups in the organic adsorbent Zr-DACA resulted in the division of the Cu2p spectrum into three doublets at 933.1 eV and 934.6 eV, 943.3 eV and 945.6 eV, and 952.2 eV and 953.9 eV. Before adsorption, the binding energy of the C=N bond in the adsorbent was 402.3 eV. When chelated with the nitrogen-containing group, a new peak of 407.2 eV appeared. The C=S peak appeared at 161.8 eV and 163.0 eV. Due to the chelation of Cu(II) ions with the sulfur-containing C=S group, a new S2p doublet appeared at 168.9 eV and 170.2 eV, proving the chelating effect of S on Cu(II) ions. The adsorption mechanism of the adsorbent was determined to be the electrostatic interaction and chelation reaction between sulfur-containing functional groups, nitrogen-containing functional groups and Cu(II) ions. By comparing the scanning electron microscope and EDS spectra before and after adsorption, it can be clearly seen that the surface is still smooth after adsorption but the adsorbent is obviously swollen. Cu peaks also appeared in the EDS, which proves that Cu(II) ions are adsorbed by the adsorbent Zr-DACA.

[0038] Zr-DACA (10 mg) and Cu(II) solution (pH = 3, 10 mL, 200 mg / L) were added to a 10 mL centrifuge tube at room temperature and shaken at 200 rpm for 20 h. The adsorbent was separated by centrifugation and the supernatant was obtained. The concentration of residual copper ions in the supernatant was determined by ICP-OES to be 68.4 mg / L, and the adsorption capacity of Zr-DACA for Cu(II) ions was 131.6 mg / g.

[0039] Zr-DACA (40 mg) and simulated wastewater (pH = 3, 40 mL, 50 mg / L, elemental composition: Pb(II), Cu(II), Ni(II), Zn(II), Co(II), Mg(II), Ca(II)) were added to a 50 mL centrifuge tube at room temperature and shaken at 200 rpm for 20 h. The adsorbent was separated by centrifugation, and the supernatant was obtained. The concentrations of lead ions, copper ions, nickel ions, zinc ions, cobalt ions, magnesium ions, and calcium ions in the supernatant were determined by ICP-OES to be 49.93 mg / mL, 2.15 mg / mL, 48.70 mg / mL, 48.2 mg / mL, 49.01 mg / mL, 48.85 mg / mL, and 49.11 mg / mL, respectively. According to the experimental data analysis, the metal adsorbent Zr-DACA has excellent selectivity for Cu(II) ions.

[0040] Zr-DACA (40 mg) and Cu(II) solution (pH = 3, 40 mL, 50 mg / L) were added to a 50 mL centrifuge tube at room temperature and shaken at 200 rpm for 20 h. The adsorbent was separated by centrifugation and the supernatant was obtained. The concentration of residual copper ions in the supernatant was determined by ICP-OES. The adsorbent was eluted with a desorption solution (40 mL) composed of 2 mL concentrated hydrochloric acid and 10% thiourea for 20 h. The concentration of copper ions in the eluent was then determined by ICP-OES, and the desorption rate was calculated. After centrifugation, the adsorbent was washed with distilled water until the solution was neutral, which completed the regeneration of the adsorbent Zr-DACA. After 5 adsorption-desorption cycles, the concentration of residual copper ions was found to be 89.71%, and the desorption rate was 85.16%.

[0041] Example 2: Preparation method of the organometallic adsorbent Zr-DACA, the specific steps are as follows:

[0042] (1) Terephthalaldehyde and aminothiourea were added to 50 mL of methanol solvent and stirred to dissolve to obtain solution A. Glacial acetic acid was added to solution A as a catalyst, and the reaction was stirred at 65 °C for 18 h. After cooling to room temperature, the solid and liquid were separated, and terephthalaldehyde diaminothiourea was recrystallized in methanol and dried under vacuum at 68 °C. The molar ratio of terephthalaldehyde to aminothiourea was 1:0.8, the molar concentration of terephthalaldehyde in solution A was 0.4 mmol / mL, and the volume ratio of glacial acetic acid to solution A was 1.0:50.

[0043] (2) Vacuum-dried terephthalaldehyde diaminothiourea and 3-formyl-4-hydroxybenzoic acid were ultrasonically dissolved in 50 mL of ethanol-DMF mixed solution. The mixture was stirred at 68 °C for 20 h, and then zirconium tetrachloride was added. The mixture was heated to 128 °C and stirred for 60 h. After cooling to room temperature, the solid and liquid were separated. The solid was washed, soaked, and vacuum dried to obtain the metal-organic adsorbent. The molar ratio of terephthalaldehyde diaminothiourea and 3-formyl-4-hydroxybenzoic acid was 1:1, the volume ratio of ethanol to DMF in the ethanol-DMF mixed solution was 1:4, and the mass ratio of the total mass of terephthalaldehyde diaminothiourea and 3-formyl-4-hydroxybenzoic acid to the mass of zirconium tetrachloride was 1.5:1.

[0044] Zr-DACA (10 mg) and Cu(II) solution (pH = 3, 10 mL, 200 mg / L) were added to a 10 mL centrifuge tube at room temperature and shaken at 200 rpm for 20 h. The adsorbent was separated by centrifugation and the supernatant was obtained. The concentration of residual copper ions in the supernatant was determined by ICP-OES to be 62.4 mg / L, and the adsorption capacity of Zr-DACA for Cu(II) ions was 137.6 mg / g.

[0045] Zr-DACA (40 mg) and simulated wastewater (pH = 3, 40 mL, 50 mg / L, elemental composition: Pb(II), Cu(II), Ni(II), Zn(II), Co(II), Mg(II), Ca(II)) were added to a 50 mL centrifuge tube at room temperature and shaken at 200 rpm for 20 h. The adsorbent was separated by centrifugation, and the supernatant was obtained. The concentrations of lead ions, copper ions, nickel ions, zinc ions, cobalt ions, magnesium ions, and calcium ions in the supernatant were determined by ICP-OES to be 49.88 mg / mL, 2.10 mg / mL, 48.65 mg / mL, 48.17 mg / mL, 49.87 mg / mL, 48.96 mg / mL, and 47.01 mg / mL, respectively. According to the experimental data analysis, the novel metal adsorbent Zr-DACA has excellent selectivity for Cu(II) ions.

[0046] Zr-DACA (40 mg) and Cu(II) solution (pH = 3, 40 mL, 50 mg / L) were added to a 50 mL centrifuge tube at room temperature and shaken at 200 rpm for 20 h. The adsorbent was separated by centrifugation and the supernatant was obtained. The concentration of residual copper ions in the supernatant was determined by ICP-OES. The adsorbent was eluted with a desorption solution (40 mL) composed of 2 mL concentrated hydrochloric acid and 10% thiourea for 20 h. The concentration of copper ions in the eluent was then determined by ICP-OES, and the desorption rate was calculated. After centrifugation, the adsorbent was washed with distilled water until the solution was neutral, which completed the regeneration of the adsorbent Zr-DACA. After 5 adsorption-desorption cycles, the concentration of residual copper ions was found to be 91.25%, and the desorption rate was 87.16%.

[0047] Example 3: Preparation method of the organometallic adsorbent Zr-DACA, the specific steps are as follows:

[0048] (1) Terephthalaldehyde and aminothiourea were added to 50 mL of methanol solvent and stirred to dissolve to obtain solution A. Glacial acetic acid was added to solution A as a catalyst. The reaction was stirred at 62 °C for 24 h. After cooling to room temperature, the solid and liquid were separated and recrystallized in methanol to obtain terephthalaldehyde diaminothiourea. The terephthalaldehyde diaminothiourea was dried under vacuum at 65 °C. The molar ratio of terephthalaldehyde to aminothiourea was 1:1, the molar concentration of terephthalaldehyde in solution A was 0.3 mmol / mL, and the volume ratio of glacial acetic acid to solution A was 0.9:50.

[0049] (2) Vacuum-dried terephthalaldehyde diaminothiourea and 3-formyl-4-hydroxybenzoic acid were ultrasonically dissolved in 50 mL of ethanol-DMF mixed solution. The mixture was stirred at 62 °C for 24 h, and then zirconium tetrachloride was added. The mixture was heated to 135 °C and stirred for 72 h. After cooling to room temperature, the solid and liquid were separated. The solid was washed, soaked, and vacuum dried to obtain the metal-organic adsorbent. The molar ratio of terephthalaldehyde diaminothiourea and 3-formyl-4-hydroxybenzoic acid was 1:1, the volume ratio of ethanol to DMF in the ethanol-DMF mixed solution was 1:3.5, and the mass ratio of the total mass of terephthalaldehyde diaminothiourea and 3-formyl-4-hydroxybenzoic acid to the mass of zirconium tetrachloride was 1.8:1.

[0050] Zr-DACA (10 mg) and Cu(II) solution (pH = 3, 10 mL, 200 mg / L) were added to a 10 mL centrifuge tube at room temperature and shaken at 200 rpm for 20 h. The adsorbent was separated by centrifugation and the supernatant was obtained. The concentration of residual copper ions in the supernatant was determined by ICP-OES to be 52.17 mg / L, and the adsorption capacity of Zr-DACA for Cu(II) ions was 147.83 mg / g.

[0051] Zr-DACA (40 mg) and simulated wastewater (pH = 3, 40 mL, 50 mg / L, elemental composition: Pb(II), Cu(II), Ni(II), Zn(II), Co(II), Mg(II), Ca(II)) were added to a 50 mL centrifuge tube at room temperature and shaken at 200 rpm for 20 h. The adsorbent was separated by centrifugation, and the supernatant was obtained. The concentrations of lead ions, copper ions, nickel ions, zinc ions, cobalt ions, magnesium ions, and calcium ions in the supernatant were determined by ICP-OES to be 49.28 mg / mL, 0.10 mg / mL, 47.85 mg / mL, 47.57 mg / mL, 48.57 mg / mL, 48.27 mg / mL, and 48.82 mg / mL, respectively. According to the experimental data analysis, the novel metal adsorbent Zr-DACA has excellent selectivity for Cu(II) ions.

[0052] Zr-DACA (40 mg) and Cu(II) solution (pH = 3, 40 mL, 50 mg / L) were added to a 50 mL centrifuge tube at room temperature and shaken at 200 rpm for 20 h. The adsorbent was separated by centrifugation and the supernatant was obtained. The concentration of residual copper ions in the supernatant was determined by ICP-OES. The adsorbent was eluted with a desorption solution (40 mL) composed of 2 mL concentrated hydrochloric acid and 10% thiourea for 20 h. The concentration of copper ions in the eluent was then determined by ICP-OES, and the desorption rate was calculated. After centrifugation, the adsorbent was washed with distilled water until the solution was neutral, which completed the regeneration of the adsorbent Zr-DACA. After 5 adsorption-desorption cycles, the concentration of residual copper ions was found to be 91.75%, and the desorption rate was 88.36%.

[0053] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A metal organic adsorbent, characterized by, The structural formula is: ； The preparation method of the metal organic adsorbent is specifically as follows: (1) p-Phthalaldehyde and aminothiourea are added to a methanol solvent to obtain solution A, a catalyst of glacial acetic acid is added to solution A, then stirring is carried out at a temperature of 60-65 DEG C for 12-24 h, cooling is carried out to room temperature, solid-liquid separation is carried out, and p-phthalaldehyde bis-thiourea is obtained by recrystallization in methanol, and vacuum drying is carried out; (2) The vacuum-dried p-phthalaldehyde bis-thiourea and 3-formyl-4-hydroxybenzoic acid are ultrasonically dissolved into an ethanol-DMF mixed solution, stirring is carried out at a temperature of 60-65 DEG C for 12-24 h, then zirconium tetrachloride is added, and stirring is carried out at a temperature of 125-135 DEG C for 48-72 h, cooling is carried out to room temperature, solid-liquid separation is carried out, the solid is washed, soaked and vacuum-dried to obtain the metal organic adsorbent.

2. The method of claim 1, wherein the metal-organic adsorbent is prepared by the steps of: The specific steps are as follows: (1) p-Phthalaldehyde and aminothiourea are added to a methanol solvent to obtain solution A, a catalyst of glacial acetic acid is added to solution A, then stirring is carried out at a temperature of 60-65 DEG C for 12-24 h, cooling is carried out to room temperature, solid-liquid separation is carried out, and p-phthalaldehyde bis-thiourea is obtained by recrystallization in methanol, and vacuum drying is carried out; (2) The vacuum-dried p-phthalaldehyde bis-thiourea and 3-formyl-4-hydroxybenzoic acid are ultrasonically dissolved into an ethanol-DMF mixed solution, stirring is carried out at a temperature of 60-65 DEG C for 12-24 h, then zirconium tetrachloride is added, and stirring is carried out at a temperature of 125-135 DEG C for 48-72 h, cooling is carried out to room temperature, solid-liquid separation is carried out, the solid is washed, soaked and vacuum-dried to obtain the metal organic adsorbent.

3. The method for preparing the organometallic adsorbent according to claim 2, characterized in that: In step (1), the molar ratio of p-phthalaldehyde to aminothiourea is 1:0.5-1.

4. The method for preparing the metal-organic adsorbent according to claim 2, characterized in that: In step (1), the molar concentration of p-phthalaldehyde in solution A is 0.1-0.5 mmol / mL.

5. The method for preparing the organometallic adsorbent according to claim 2, characterized in that: In step (1), the volume ratio of the catalyst glacial acetic acid to solution A is 0.5-1:

50.

6. The method for preparing the organometallic adsorbent according to claim 2, characterized in that: In step (2), the molar ratio of p-phthalaldehyde bis-thiourea to 3-formyl-4-hydroxybenzoic acid is 1:0.8-1.

2.

7. The method for preparing the organometallic adsorbent according to claim 2, characterized in that: In step (2), the volume ratio of ethanol to DMF in the ethanol-DMF mixed solution is 1:3-4.

8. The method for preparing the organometallic adsorbent according to claim 2, characterized in that: In step (2), the mass ratio of the total mass of p-phthalaldehyde bis-thiourea and 3-formyl-4-hydroxybenzoic acid to the mass of zirconium tetrachloride is 1-2:

1.

9. The metal organic adsorbent of claim 1 is used for targeted adsorption of copper ions in a solution.

Images