Cu (II) complex single crystal for adsorbing Hg < 2 + > ions and preparation method of Cu (II) complex single crystal

Abstract

The invention belongs to the field of coordination chemistry and adsorption, and discloses a copper (II) complex single crystal for adsorbing Hg < 2 + > ions and a preparation method thereof. The chemical formula of the Cu (II) complex single crystal is [(Cu4L (5-OH-BDC) (SO4) 3 (H2O) 7] n, L is 25, 26, 27, 28-tetra [(4-pyridyl methyl) oxy] calix [4] arene, and 5-OH-BDC is a group after two hydrogen atoms in 5-hydroxyisophthalic acid are lost; the crystal belongs to a monoclinic system, the space group is C2 / m, a is equal to 20.046 (4), b is equal to 43.563 (9), c is equal to 14.895 (3), alpha is equal to 90.000 degrees, beta is equal to 96.99 (3) degrees, gamma is equal to 90.000 degrees, and V is equal to 12910.6 (50) 3. The adsorption capacity of the copper complex single crystal to mercury ions reaches 549.2 mg / g, the preparation method is simple, and the copper complex single crystal has a very good application prospect.

Description

Technical Field

[0001] The present invention relates to the field of coordination chemistry and adsorption, and in particular to a copper complex single crystal and a preparation method thereof and its application in adsorbing Hg 2+ Ionic applications. Background Art

[0002] Mercury is widely used in precious metal refining, pigment production and modern technology such as thermometers, electronic components, industrial catalysis and other fields, but its improper handling and accidental leakage pose a severe challenge to organisms. With the rapid progress of industry and technology, heavy metal pollution in water bodies, especially mercury ions (Hg 2+ ) has become a major concern for global ecosystem stability and public health. 2+ The ion is non-biodegradable, highly toxic and persistent. It can accumulate in organisms. When in excess, it can cause damage to cell function and cause profound damage to the kidneys, brain and central nervous system. It has been designated as one of the priority hazardous substances by the Agency for Toxic Substances and Disease Registry. Therefore, it is necessary to develop high-capacity and high-selectivity technologies to remove Hg from aquatic environments. 2+ .

[0003] Given that Hg 2+ Due to the serious harm of heavy metal ions, the scientific research community is actively exploring and developing efficient and highly selective technologies to purify this toxic ion in the aquatic environment. Among many solutions, adsorption stands out with its economy and efficiency, becoming an important means of removing heavy metal pollution. Researchers are committed to innovating adsorption materials such as activated carbon, zeolite, clay, etc. Although they have been used, they still face bottlenecks in adsorption capacity and selectivity due to their single structure and difficulty in functionalization.

[0004] Metal-organic framework materials (MOFs) have shown great potential in the field of adsorption due to their unique advantages - high specific surface area, flexible chemical composition and pore structure control ability. Through carefully designed ligands or post-functionalization synthesis strategies, MOFs can introduce a variety of functional groups and create abundant active sites, thereby achieving precise capture of target pollutants. Therefore, the use of metal-organic framework materials (MOFs) for improvement can achieve Hg in aquatic environments. 2+ Removal is currently a potential research direction. Summary of the invention

[0005] Based on the current state of the art, the present invention aims to provide a copper complex single crystal with high capacity, high selectivity, good stability and convenient use, which can adsorb Hg in water. 2+ Another object is to provide a method for preparing the same.

[0006] To achieve the above-mentioned purpose, the present invention cleverly embeds sulfate groups into the framework of Cu(II) complexes based on the oxygen atoms in sulfate groups and Hg 2+ ions, and sulfur atoms and Hg 2+ Weak interaction of ions enables high capacity and high selectivity in removing Hg from water 2+ Ions. The specific technical solution is as follows:

[0007] The Cu(II) complex single crystal has the chemical formula: [(Cu 4 L(5-OH-BDC)(SO 4 ) 3 (H 2 O) 7 ] n , where L = 25,26,27,28-tetrakis[(4-pyridylmethyl)oxy]calix[4]arene, 5-OH-BDC is the radical after the dicarboxylic acid in 5-hydroxyisophthalic acid loses two hydrogen atoms; it belongs to the monoclinic system, and the space group is C2 / m, α=90.000°, β=96.99(3)°, γ=90.000°,

[0008] The preparation method comprises the following steps: dissolving copper sulfate pentahydrate, ligand L and 5-hydroxyisophthalic acid in anhydrous ethanol and deionized water, sealing the mixture in a reaction bottle, subjecting the mixture to ultrasonic reaction at room temperature, and then heating the mixture in a constant temperature oven. After the reaction is completed, the mixture is taken out and cooled to room temperature, and the obtained crystals are filtered and washed to obtain the target product.

[0009] The molar ratio of the copper sulfate pentahydrate, the ligand L and the 5-hydroxyisophthalic acid is in the range of 2-4:1:1-2.

[0010] The complex single crystal can be used as an adsorbent to remove Hg from water 2+ ion.

[0011] The advantages of the present invention are that the copper complex single crystal can not only stably exist in water, but also has sulfate groups in its structure, which is conducive to the reaction with Hg 2+ Ion action, thereby adsorbing and removing Hg in water in large quantities 2+ Ions, achieving a higher adsorption capacity. The adsorption capacity of mercury ions by the copper complex single crystal reaches 549.2 mg / g, and the preparation method of the invention is simple and has a good application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a secondary building block in the copper complex crystal of the present invention;

[0013] Figure 2is a single crystal structure diagram of the adsorbent of the present invention;

[0014] Figure 3 1 is the powder diffraction pattern of the copper complex of the present invention; 2 is the experimental powder diffraction pattern of the copper complex prepared by the present invention;

[0015] Figure 4 The adsorption isotherm diagram of the complex of the present invention for adsorbing mercury ions of different concentrations in water;

[0016] Figure 5 The figure is a kinetic diagram of the adsorption of mercury ions (10 ppm) in water by the complex of the present invention;

[0017] Figure 6 The figure is a selectivity diagram of the complex of the present invention for adsorbing mercury ions in water. DETAILED DESCRIPTION

[0018] The present invention will be further described below by way of examples:

[0019] Example 1: Synthesis of copper complex single crystal adsorbent

[0020] Copper sulfate pentahydrate (9.6 mg, 0.0384 mmol), ligand L (7.9 mg, 0.010 mmol) and 5-hydroxyisophthalic acid (3.6 mg, 0.0198 mmol) were dissolved in anhydrous ethanol and deionized water, sealed in a reaction bottle, ultrasonicated at room temperature for 5 minutes, placed in a constant temperature oven at 80°C for two days, taken out and cooled to room temperature to obtain dark green block crystals, which were filtered and washed to obtain the target product, which was the copper complex single crystal adsorbent.

[0024] Single crystals of suitable size were selected under a microscope and subjected to X-ray diffraction experiments at room temperature. Mo-Kα rays monochromatized by a graphite monochromator were used on a Bruker SmartApex-IICCD diffractometer. Diffraction data were collected in φ–ω mode. Data reduction was performed using the Bruker SAINT program. Diffraction data for some structures were absorption corrected using the SADABS program. The crystal structure was solved by a direct method combined with difference Fourier synthesis. All non-hydrogen atomic coordinates and anisotropy parameters were corrected by full-matrix least squares, and the C–H atomic positions were determined by theoretical calculations. The secondary building blocks in the complex crystals are shown in Figure 1 ; The crystal structure of the complex is shown in Figure 2 ; Detailed crystal measurement data are shown in Table 1.

[0021] Table 1 Main crystallographic data of the complexes

[0022] Example 2: Test on the adsorption of mercury ions by copper complexes

[0023] 5 mg of the dark green block crystals prepared in Example 1 were added to 50 mL of mercury ion aqueous solution of different concentrations, and stirred at room temperature. After reaching adsorption equilibrium, the equilibrium concentration of mercury ions was detected by atomic absorption spectrometer. The test showed that the adsorption capacity of the new copper complex single crystal of the present invention reached 549.2 mg / g. Figure 4 , proving that the copper complex single crystal has a large adsorption capacity.

[0024] 10 mg of dark green block crystals prepared in Example 1 were added to 10 mL of 10 ppm mercury ion aqueous solution and stirred at room temperature. Samples were taken at different time periods and the mercury ion concentration was detected by atomic absorption spectrometer. The test showed that 85.26% of the mercury ions were adsorbed and removed at equilibrium. Figure 5 .

[0025] The dark green block crystals prepared in Example 1 were added into aqueous solutions containing different metal ions (10 ppm), including Hg 2+ , Li + 、Na + , K + , Ca 2+ Mg 2+ 、Ni 2+ 、Zn 2+ , Pb 2+ 、Cd 2+ and Eu 3+ After reaching adsorption equilibrium, Hg was detected by atomic absorption spectrometer. 2+ , Li + 、Na + , K + , Ca 2+ Mg 2+ 、Ni 2+ 、Zn 2+ , Pb 2+ 、Cd 2+ Balanced concentration, inductively coupled plasma optical emission spectrometry elemental analyzer to detect Eu 3+ Concentration. Tests show that the removal effect of mercury ions is much higher than that of other metal ions. Figure 6 , proving that the copper complex single crystal of the present invention has a high adsorption selectivity for mercury ions.

[0026] The copper complex single crystal of the present invention has a high adsorption capacity and can absorb and remove Hg in water in large quantities. 2+ ions, and has strong anti-interference ability, and has good application prospects.

Claims

1. A Cu(II) complex single crystal, characterized in that: Its chemical formula is: [(Cu4L(5-OH-BDC)(SO4)3(H2O)7] n , wherein L = 25,26,27,28-tetrakis[(4-pyridylmethyl)oxy]calix[4]arene, 5-OH-BDC is the radical after the dicarboxylic acid in 5-hydroxyisophthalic acid loses two hydrogen atoms; It belongs to the monoclinic system, and the space group is C2 / m. α=90.000°, β=96.99(3)°, γ=90.000°, 2. The method for preparing a Cu(II) complex single crystal according to claim 1, characterized in that: It is achieved by the following method: copper sulfate pentahydrate, ligand 25,26,27,28-tetrakis[(4-pyridylmethyl)oxy]calix[4]arene and 5-hydroxyisophthalic acid are dissolved in anhydrous ethanol and deionized water, sealed in a reaction bottle, subjected to ultrasonic reaction at room temperature, then heated and placed in a constant temperature oven, taken out and cooled to room temperature after the reaction is completed, and the obtained crystals are filtered and washed to obtain the target product.

3. The method for preparing a Cu(II) complex single crystal according to claim 2, characterized in that: The molar ratio of the copper sulfate pentahydrate, the ligand 25,26,27,28-tetrakis[(4-pyridylmethyl)oxy]calix[4]arene and 5-hydroxyisophthalic acid is in the range of 2-4:1:1-2.

4. The use of the Cu(II) complex single crystal according to claim 1, characterized in that: It is used for Hg in water by adsorption 2+ Removal of ions.

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