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    • 专利摘要:
    The invention relates to the technical field of preparing adsorption and separation functional materials, and more particularly to a method for preparing an amidoxime-functionalized hollow porous adsorbent using CO 2 as an emulsion pattern; the steps are: first, preparing silica nanoparticles and MF-HP, adding MF-HP and PEA to ethanol, by ultrasonic, water bath reaction, water washing, ethanol washing and drying, MF-NH2-HP is obtained, adding aqueous glutaraldehyde solution, by water bath , water washing, alcohol washing and drying, MF-CHO-HP is obtained, then DAMN is added to ethanol solution, through water bath, water washing, alcohol washing and drying, MF-CN-HP is obtained, adding hydroxylamine hydrochloride in the mixed solution of water and ethanol, after the reaction by water washing, alcohol washing and drying, MF-AO-HPS is obtained. The present invention enables the subsequent modification of a large number of sites of action by grafting of PEA, in combination with the hollow and porous structure, not only improves the adsorption capacity of adsorbing U(VI), but also accelerates the mass transfer kinetics.
    公开号:CH717047B1
    申请号:CH01488/20
    申请日:2020-05-27
    公开日:2022-01-14
    发明作者:Bai Xue；Pan Jianming；Liu Jinxin
    申请人:Univ Jiangsu；
    IPC主号:
    专利说明:

    TECHNICAL AREA
    The invention relates to the technical field of preparing adsorption and separation functional materials, and more particularly to a method for preparing an amidoxime-functionalized hollow porous adsorbent using CO 2 as an emulsion pattern.
    STATE OF THE ART
    [0002] Because of their particular use in the nuclear industry, naturally occurring uranium resources have become a strategic resource for the nuclear industry. The proven uranium resources exist mainly in seawater in the form of hexavalent uranium (U(VI)), about 4.5 billion tons, i.e. that is, seawater is a potential source of uranium resources. The relative difficulty of extracting large amounts of uranium from seawater severely limits its wide application. Due to the radioactivity and chemical toxicity of uranium, the uranium contained in seawater is not only harmful to humans and the environment, but also dangerous. Therefore, extracting uranium from seawater has not only economic value, but also significance for environmental protection and scientific development. Many existing methods exist to recover U(VI) from seawater, such as electrodialysis, extraction, chemical precipitation, organic-inorganic ion exchange and adsorption separation, etc. Adsorption method, which has the advantages of high adsorption efficiency, low manufacturing cost, low secondary pollution, has been developed as a mature technology and easy to use, often used to extract uranium from seawater. However, the extraction of uranium from seawater has faced major challenges, e.g. B, a low concentration (about 3.3 ppb), the presence of a large number of competing ions, and complex chemical and biological environments. In order to effectively recover U(VI) from seawater, there is an urgent need to develop an environmentally friendly, highly selective and efficient adsorbent.
    [0003] Many types of adsorbents are available for ion collection. Among these, the hollow porous adsorbent (HPS) has attracted great attention due to its low density, clear structure and strong bearing capacity. The Pickering emulsion pattern method is one of the most commonly used methods for manufacturing hollow porous adsorbents. Because of its unique spatial configuration, the amidoxime group can coordinate with U(VI) to achieve selective adsorption. Using this principle, the surface of the material can be modified with amidoxime groups to give it the ability to selectively adsorb U(VI).
    The traditional Pickering emulsion pattern method usually suffers from the complex internal phase elution process, and the use of organic solvents leads to serious environmental problems, limited dimensional control, and large size. The functional monomer is directly involved in the polymerization, resulting in a large number of functional sites within the polymer. Not only is the rate of mass transfer slow, but also some functional sites cannot participate in the reaction and therefore cause unnecessary losses. In order to avoid the above shortcomings, a new material for selective uranium extraction needs to be studied.
    CONTENT OF THE PRESENT INVENTION
    In view of the shortcomings of the prior art, the object of the present invention is to overcome the problems of difficult elution of the internal phase and difficult control of the structure during the preparation of the existing Pickering emulsion pattern method and an amidoxime-functionalized air-in -water emulsion pattern method for preparing the hollow porous absorbent, using the amidoxime groups as selective ligands and melamine resin as substrate, a hollow porous adsorbent (MF-AO-HPS) grafted with amidoxime functional groups on the surface is prepared.
    In order to achieve the above technical task, the technical solutions in the present invention are adopted as follows:
    (1) Production of silica nanoparticles;
    [0007] Adding a specific amount of tetraethylorthosilicate (TEOS) to ethanol. After heating the water bath and raising the temperature, a certain amount of a mixture of NH3·H2O and water is added. Then, the resulting mixed solution is reacted under magnetic stirring for a period of time. After the completion of the reaction, the product is collected by centrifugation, washed three times with deionized water and ethanol, and dried to obtain silica nanoparticles;
    (2) production of a hollow porous melamine resin;
    Dispersing the silica nanoparticles obtained in step (1) in deionized water to obtain an aqueous silica dispersion, and then under specified temperature conditions, melamine is added to the mixed solution of formaldehyde solution and glutaraldehyde solution. Adjusting the pH of the mixed solution, keep stirring and reacting for a while after the solution turns from milky white to clear; after the completion of the reaction, an aqueous silica dispersion is added with stirring to react again; After the reaction, cooling to a certain temperature and adjusting the pH again, after the reaction, the polymerization reaction is carried out under water bath conditions. Finally, the product is collected by centrifugation, washed with deionized water and ethanol, and dried to obtain a powder sample; the powder sample is processed using the added hydrofluoric acid solution for etching. The product collected after centrifugation is washed with deionized water and ethanol and centrifuged again to obtain the product. After drying, a hollow-pore melamine resin is obtained, which is referred to as MF-HP; (3) dispersing the MF-HP and polyethylene polyamine (PEA) prepared in step (2) in ethanol to obtain a mixed solution A and then sonicating, the mixed solution A is reacted under a water bath with magnetic stirring; Centrifugation after the reaction, the product obtained is washed with ethanol and collected again by centrifugation to obtain hollow porous melamine resin polymer microspheres grafted with amino groups on the surface and named MF-NH2-HP; then MF-NH2-HP, glutaraldehyde is added to ethanol to obtain the mixed solution B, and then a mixed solution B is reacted in a water bath under magnetic stirring. After the reaction, the product is washed with deionized water and ethanol, and centrifuged to obtain hollow porous melamine resin polymer microbeads grafted with aldehyde group on the surface and called MF-CHO-HP; (4) Suspend the MF-CHO-HP prepared in step (3) and diaminomaleonitrile (DAMN) in 40-60 ml of ethanol E to obtain a mixed solution C, and then ultrasonic treatment, the mixed solution C is under magnetic stirring to Reaction placed in water bath, post-reaction centrifugation to obtain a hollow porous melamine resin grafted with nitrile groups on the surface and denoted as MF-CN-HP, and finally adding the ethanol F to deionized water to obtain a mixture of ethanol and to get water. MF-CN-HP and hydroxylamine hydrochloride is added to the mixed solution and after pH adjustment, reacted in water bath; After the reaction, centrifugation, the product is collected by centrifugation, washed with deionized water and ethanol, and dried to obtain an amidoxime-functionalized hollow porous melamine resin microsphere, denoted as MF-AO-HPS.
    The same procedure as in step (3) except that MF-CHO-HP is replaced by MF-HP to obtain another adsorbent that does not graft PEA and is called MF-nPEA-AO-HPS.
    Preferably, the amount ratio of tetraethylorthosilicate, ethanol, NH3·H2O and water in step (1) is 8.0-10g: 170-190ml: 9.0-11ml: 9.0-10g, the reaction temperature is 30-40 °C and the reaction time is 2.0-4.0 h.
    Preferably, the specified temperature condition in step (2) is 80-90°C.
    Preferably, the amount ratio of melamine, mixed formaldehyde and glutaraldehyde solution and silica dispersion in step (2) is 1.0-2.0g: 2.0-4.0ml: 5.0-15ml; the volume fraction of the formaldehyde solution is 37%, the volume fraction of the glutaraldehyde solution is 25%, the concentration of the aqueous silica dispersion is 10% by weight.
    Preferably, the pH adjustment in step (2) is to use a Na2CO3 solution to adjust the pH to 9.0-10.0, the concentration of the Na2CO3 solution is 2.0M.
    Preferably, the stirring condition in the step (2) is 1200 to 1600 rpm, the reaction continued period is 3.0 to 5.0 minutes, the reaction time after the addition of the silica aqueous dispersion is 10 to 30 minutes.
    Preferably, the temperature is cooled to the specified temperature of 30-50°C by the cooling in step (2), the process of readjusting the pH is: adding 2.0 M HCl dropwise to adjust the pH to 5 ,0-6.0 to adjust, the reaction time after adjusting the pH again is 10-30 min.
    Preferably, the temperature of the water bath in step (2) is 30-50°C, the polymerization reaction time is 3.0-5.0 hours, the volume concentration of the hydrofluoric acid solution is 2%, the drying temperature is uniformly 60-80°C.
    Preferably, the proportion of MF-HP, polyethylene polyamine and ethanol in step (3) is 0.3-0.5 mg: 3.0-5.0 g: 40-60 ml.
    Preferably, in the step (3), the ultrasonic treatment time is 5.0 to 10 minutes, the temperature of the water bath of the mixed solution A is 30 to 40°C, and the reaction time is 8.0 to 16 hours.
    Preferably, the amount ratio of MF-NH 2 -HP, glutaraldehyde and ethanol in step (3) is 0.2-0.4 mg: 8.0-12 ml: 30-50 ml, the volume fraction of glutaraldehyde is 25 %.
    Preferably, the water bath temperature of the mixed solution B in step (3) is 20 to 30°C and the reaction time is 8.0 to 16 hours.
    Preferably, the amount ratio of MF-CHO-HP, diaminomaleonitrile and ethanol E in step (4) is 0.2-0.6 mg: 0.4-1.2 mg: 40-60 ml.
    Preferably, the ultrasonic treatment time of the mixed solution C in step (4) is 5.0 to 10 minutes, the water bath temperature is 20 to 30°C, and the reaction time is 2.0 to 4.0 hours.
    Preferably, the volume ratio of ethanol F and water in step (4) is 9:1, the quantity ratio of MF-CN-HP, hydroxylaminohydrochloride, mixture of ethanol F and water is 0.2-0.6 mg: 2, 0-6.0g : 40-60ml.
    Preferably, the pH adjustment in step (4) is to adjust the pH to 8.0 to 9.0 with 1.0M NaOH, the temperature of the water bath is 70 to 90°C, and the reaction time of the water bath is 4.0 to 8.0 h.
    Preferably the drying temperature in step (4) is 60-80°C.
    Among these, ethanol E and ethanol F are both ethanol, and the letters E and F are only for distinguishing terms.
    The advantageous effects of the present invention: (1) The present invention selects the amidoxime group as the selective ligand for U(VI), with the hollow porous melamine resin as the substrate and the air-in-water emulsion pattern method, the surface becomes made of amidoxime functionalized hollow porous. In this way, the specific adsorption of U(VI) is achieved. (2) Through the air-in-water emulsion pattern method, the present invention produces the hollow porous melamine resin polymer microspheres rich in aldehyde groups on the surface, in which the shortens the U(VI) diffusion path and improves the mass transfer kinetics, the contained aldehyde group avoids bond instability caused by subsequent modification and thereby simplifies the manufacturing process; the grafting by PEA allows the modification of the high-density action sites, the high-density amidoxime sites grafted on the surface of MF-AO-HP can interact with a large amount of U(VI), thereby increasing the adsorption capacity of the adsorbent will. This can be seen from the experimental results of pH response of MF-AO-HPS and MF-nPEA-AO-HPS, where under different pH conditions MF-AO-HPS has higher adsorption capacity for U(VI) than MF-nPEA- AO HPS.
    BRIEF DESCRIPTION OF THE DRAWING
    Figure 1a and 1b are SEM images of the MF-HP produced in Example 1, c and d are TEM images of the MF-HP produced in Example 1. Figure 2 is the infrared spectra of MF-HP, MF-NH2-HP, MF-CHO-HP, MF-CN-HP and MF-AO-HPS prepared in Example 1. Figure 3 is the zeta potential spectra of MF-HP, MF-NH2-HP, MF-AO-HPS and MF-nPEA-AO-HPS prepared in Example 1. Figure 4a is the XPS spectrum of the MF-AO-HPS prepared in Example 1, Figure 4b is the high-resolution C Is spectrum of the MF-AO-HPS prepared in Example 1, Figure 4c is the high-resolution N Is spectrum of the Example 1 produced MF-AO-HPS. Figure 5 is the organic element analysis spectrum of MF-HP, MF-NH2-HP, MF-CHO-HP, MF-CN-HP and MF-AO-HPS prepared in Example 1. Figure 6 is a solid-state NMR carbon spectrum of the MF-AO-HPS prepared in Example 1. Figure 7 is a thermogravimetric analysis chart of the MF-AO-HPS prepared in Example 1. Figure 8 shows the effect of pH on the adsorption capacity of the MF-AO-HPS, MF-nPEA-AO-HPS and MF-HP prepared in Example 1. Figure 9 shows the adsorption kinetics and its model fitting curve of the MF-AO-HPS prepared in Example 1. Figure 10 shows the effect of temperature on the adsorption equilibrium of MF-AO-HPS prepared in Example 1 on the adsorption equilibrium of uranyl ions and its model fit curve. Figure 11 shows the selective adsorption capacity of the MF-AO-HPS prepared in Example 1. Figure 12 shows the adsorption regeneration performance of the MF-AO-HPS prepared in Example 1.
    DETAILED DESCRIPTION
    In the specific embodiment of the present invention, the evaluation of the recognition performance is performed according to the following procedure: It is completed by a static adsorption experiment. Adsorption is carried out with 2.0 mg MF-AO-HPS, MF-nPEA-AO-HPS and MF-HP on U(VI) in the range of pH = 3.0-9.0, the content of U(VI ) after adsorption is measured with inductively coupled plasma emission spectrometer and optimal adsorption pH is determined according to the results; To study the maximum adsorption capacity of MF-AO-HPS, adsorption equilibrium tests in the range of U(VI) concentration of 10-500mg/1 are carried out, using Langmuir model Freundlich model, the adsorption data are fitted, the adsorption capacity is at it determined based on the results. After saturated adsorption, several other substances with the same structure as uranyl ions were selected as competitive adsorbents to study selective adsorption performance and its adsorption regeneration performance of MF-AO-HPS.
    The present invention is further described below in connection with specific examples.
    Example 1:
    (1) Production of silica nanoparticles;
    Silica nanoparticles are prepared by the Stöber method: In a flask, 8.735 g of TEOS is added to 180 ml of ethanol, after which the water bath is heated to 35°C, a mixed solution of 10 ml of NH3·H2O and 9.48 g water is added dropwise. The resulting mixed solution is then reacted with magnetic stirring for 3.0 hours, after completion of the reaction, the product is collected by centrifugation and washed three times each with deionized water and ethanol; after drying, silica nanoparticles with a diameter of 180-200 nm are obtained;
    (2) production of a hollow porous melamine resin;
    At 85 °C, 1.26 g of melamine is added to 3.0 ml of a mixed solution of 37% formaldehyde and 25% glutaraldehyde (v/v, 2:1), and then mixed with a 2.0 M Na2CO3 solution, the pH is adjusted to 9.5, with stirring at 1500rpm, the reaction is continued for 3.0 minutes after the solution turns from milky white to clear. Then 10 ml of a 10% by weight aqueous silica dispersion is added with stirring and the reaction is continued for 20 minutes. Then the solution is cooled to 40°C and 2.0 M HCl is added dropwise to adjust the pH to 5.5, the reaction then continues for 20 minutes, stopping the stirring and polymerizing for 4.0 hours in the 40° water bath C; Finally, collecting the product by centrifugation, washing the product with deionized water and ethanol and drying it to obtain a powder sample. In the obtained powder, 2% HF solution is added to the etch at room temperature. The product is collected by centrifugation and washed three times each with deionized water and ethanol. The product is collected again by centrifugation and dried at 60°C to obtain a hollow-pore melamine resin called MF-HP;
    (3) MF-AO-HPS can be obtained by the following procedure: First, 0.4 g of MF-HP powder and 4.0 g of PEA are dispersed in 50 ml of ethanol in a flask, and then 5.0 min long sonicated. Then, the resulting mixture is reacted with magnetic stirring at 35°C in a water bath for 12 hours, after which the product is collected by centrifugation and washed three times with ethanol to obtain hollow porous melamine resin polymer microspheres having grafted amino groups on the surface, which are referred to as MF -NH2-HP; second, a mixture of 0.4 g MF-NH2-HP, 10 mL 25% GA and 40 mL ethanol is placed in a flask and then allowed to react for 12 h at 35 °C water bath under magnetic stirring; Washing the product three times with water to remove excess GA, then washing the product twice with ethanol, and then by centrifugation, the hollow porous melamine resin polymer microspheres grafted with aldehyde groups on the surface are collected and designated as MF-CHO-HP ;
    (4) 0.4 g MF-CHO-HP and 0.8 g DAMN are suspended in 50 ml ethanol, sonicated for 5.0 min and reacted for 3.0 h at 25 °C under magnetic stirring, then the Product collected to obtain a hollow porous melamine resin grafted with nitrile group on surface, and called MF-CN-HP, finally 0.4 g MF-CN-HP and 4.0 g NH2OH HCl in 50 ml of a mixed solution of H2O/ethanol (v/v, 1:9), the pH is adjusted to 8.0 with 1.0 M NaOH, and the resulting mixture is heated in a water bath for 6.0 hours Reacted at 80°C, then it is centrifuged, rinsed with deionized water and ethanol, and dried at 60°C to obtain the porous melamine resin microspheres functionalized with amidoxime, which is referred to as MF-AO-HPS.
    Using the same procedure as in step (3), except that MF-CHO-HP is replaced by MF-HP to obtain another adsorbent that does not graft PEA and is called MF-nPEA-AO-HPS.
    Figure 1 shows the SEM and TEM images of MF-HP; from the SEM image, we can find that the microspheres are monodisperse, its diameter is about 2.0 µm and the surface is porous, as can be seen from the TEM image, the microspheres are hollow.
    The grafting and chemical modification of MF-AO-HPS are studied by FT-IR, XPS and OEA, the zeta potential of each compound and the CP-MAS<13>C NMR spectrum. The FT-IR spectra of MF-HP, MF-NH2-HP, MF-CHO-HP, MF-CN-HP and MF-AO-HPS are shown in Figure 2, where MF-CN-HP spectrum lies at 2210 cm<-1> the characteristic adsorption peak of C=N, indicating the successful modification of DAMN. The disappearance of the absorption peak in the MF-AO-HPS spectrum is the result of the reaction with NH2OH·HCl.
    In Figure 3 it can be seen that the zeta potential changes after each reaction. This is because the functional groups on the surface of the material are different after modification of different substances, so the displayed zeta potentials are also different. This can reflect the success of each modification step and the successful preparation of each material.
    In the XPS spectrum of MF-AO-HPS, as shown in Figure 4a, it shows three strong peaks at 284.83, 399.03 and 535.88 eV corresponding to the nuclear energy levels of C 1s, N 1s, respectively and O 1s, FIG. 4b shows the high-resolution C 1s spectrum, which shows that the high-resolution C 1s spectrum can be divided into three peaks, the CC, CH and C=N. Figure 4c is the high resolution N 1 spectrum of MF-AO-HPS, this can be divided into three characteristic absorption peaks representing N-O, C=N and. be assigned to N-H.
    Figure 5 shows the changes in carbon and nitrogen atom content in each product. After testing, the carbon atom content in MF-HP is less than nitrogen atom, and the carbon atom content in PEA is more than nitrogen atom. Therefore, the carbon content in MF-NH2-HP is relatively increased compared to MF-HP, while the nitrogen content is relatively decreased. By the same token, MF-CHO-HP and MF-CN-HP contain more carbon than nitrogen, and MF-AO-HPS contains more nitrogen than carbon.
    FIG. 6 shows the CP-MAS<13>C-NMR spectrum of MF-AO-HPS. It contains four main peaks of 48.12ppm, 105.80ppm, 162.72ppm and 219.75ppm, such peaks correspond to the carbon absorption peaks of -CH2-NH-, -C=C-, C=NOH and C=O , all the above results can prove the successful production of MF-AO-HPS, then the stability of MF-AO-HPS is determined by thermogravimetric analysis (TGA).
    [0042] As shown in FIG. 7, in the MF-AO-HPS curve, a 1.75% weight loss is observed between 200°C and 360°C, which is due to the loss of superficial grafting of amidoxime groups, the weight loss of 1.60% at 360 °C to 600 °C is due to loss of grafted PEA. The low weight loss of MF-AO-HPS indicates that it has good stability.
    Example 2:
    (1) Production of silica nanoparticles;
    [0043] Silica nanoparticles are prepared by the Stöber method: In a flask, 8.0 g of TEOS is added to 170 ml of ethanol after the water bath is heated to 30°C, a mixed solution of 9.0 ml of NH3 H2O and 9.0 g of water is added dropwise. The resulting mixed solution is then reacted with magnetic stirring for 2.0 hours, after completion of the reaction, the product is collected by centrifugation and washed three times each with deionized water and ethanol; after drying, silica nanoparticles with a diameter of about 200 nm are obtained;
    (2) production of a hollow porous melamine resin;
    At 80°C, 1.0 g of melamine is added to 2.0 ml of a mixed solution of 37% formaldehyde and 25% glutaraldehyde (v/v, 2:1), and then mixed with a 2.0 M Na2CO3 solution, the pH is adjusted to 9.0, with stirring at 1200rpm, the reaction is continued for 4.0 minutes after the solution turns from milky white to clear. Then 5 ml of a 10% by weight aqueous silica dispersion is added with stirring and the reaction is continued for 10 minutes. Then the solution is cooled to 30°C and 2.0 M HCl is added dropwise to adjust the pH to 5.0, the reaction then continues for 10 minutes, stop stirring and polymerize for 3.0 hours in the 30° water bath C; Finally, collecting the product by centrifugation, washing the product with deionized water and ethanol and drying it to obtain a powder sample. In the obtained powder, 2% HF solution is added to the etch at room temperature. The product is collected by centrifugation and washed three times each with deionized water and ethanol. The product is collected again by centrifugation and dried at 60°C to obtain a hollow-pore melamine resin called MF-HP;
    (3) MF-AO-HPS can be obtained by the following procedure: First, 0.3 g of MF-HP powder and 3.0 g of PEA are dispersed in 40 ml of ethanol in a flask, and then 8.0 min long sonicated. Then, the resulting mixture is reacted with magnetic stirring at 30°C in a water bath for 8.0 hours, after which the product is collected by centrifugation and washed three times with ethanol to obtain hollow porous melamine resin polymer microspheres having grafted amino groups on the surface, which referred to as MF-NH2-HP; second, a mixture of 0.2 g MF-NH2-HP, 8 ml 25% GA and 30 ml ethanol is placed in a flask, and then allowed to react for 8.0 h at 30 °C water bath under magnetic stirring; Washing the product three times with water to remove excess GA, then washing the product twice with ethanol, and then by centrifugation, the hollow porous melamine resin polymer microspheres grafted with aldehyde groups on the surface are collected and designated as MF-CHO-HP ;
    (4) 0.2g MF-CHO-HP and 0.4g DAMN are suspended in 40mL ethanol, sonicated for 8.0min and reacted for 2.0h at 20°C under magnetic stirring, then the Product collected to obtain a hollow porous melamine resin grafted with nitrile group on surface and named as MF-CN-HP, finally 0.2 g MF-CN-HP and 2.0 g NE2OH HCl in 40 ml a mixed solution of H2O/ethanol (v/v, 1:9), the pH is adjusted to 8.5 with 1.0 M NaOH and the resulting mixture is heated in a water bath at 70 for 4.0 hours °C, then it is centrifuged, rinsed with deionized water and ethanol, and dried at 70 °C to obtain MF-AO-HPS.
    [0047] Direct reaction of MF-HP with DAMN and NH 2 OH·HCl gives another adsorbent without grafting of PEA, named MF-nPEA-AO-HPS.
    Example 3
    (1) Production of silica nanoparticles;
    Silica nanoparticles are prepared by the Stöber method: In a flask, 10 g TEOS is added to 190 ml ethanol, after the water bath is heated to 40°C, a mixed solution of 11 ml NH3·H2O and 10 g water is added dropwise. The resultant mixed solution is then reacted with magnetic stirring for 4.0 hours, after completion of the reaction, the product is collected by centrifugation and washed three times each with deionized water and ethanol; after drying, silica nanoparticles with a diameter of about 200 nm are obtained;
    (2) production of a hollow porous melamine resin;
    At 90 °C, 2.0 g of melamine is added to 4.0 ml of a mixed solution of 37% formaldehyde and 25% glutaraldehyde (v/v, 2:1), and then mixed with a 2.0 M Na2CO3 solution, the pH is adjusted to 10.0, with stirring at 1600rpm, the reaction is continued for 5.0 minutes after the solution turns from milky white to clear. Then 15 ml of a 10% by weight aqueous silica dispersion is added with stirring and the reaction is continued for 30 minutes. Then the solution is cooled to 50°C and 2.0 M HCl is added dropwise to adjust the pH to 6.0, the reaction then continues for 30 minutes, stop stirring and polymerize for 5.0 hours in the 50° water bath C; Finally, collecting the product by centrifugation, washing the product with deionized water and ethanol and drying it to obtain a powder sample. In the obtained powder, 2% HF solution is added to the etch at room temperature. The product is collected by centrifugation and washed three times each with deionized water and ethanol. The product is collected again by centrifugation and dried at 60°C to obtain a hollow-pore melamine resin called MF-HP;
    (3) First, 0.5 g of MF-HP powder and 5.0 g of PEA are dispersed in 60 ml of ethanol in a flask and then sonicated for 10 min. Then, the resulting mixture is reacted under magnetic stirring at 40°C in a water bath for 16 hours, after which the product is collected by centrifugation and washed three times with ethanol to obtain hollow porous melamine resin polymer microspheres having grafted amino groups on the surface, which are referred to as MF -NH2-HP; second, a mixture of 0.4 g MF-NH2-HP, 12 mL 25% GA and 50 mL ethanol is placed in a 100 mL flask and then allowed to react for 16 h at 40 °C water bath under magnetic stirring; Washing the product three times with water to remove excess GA, then washing the product twice with ethanol, and then by centrifugation, the hollow porous melamine resin polymer microspheres grafted with aldehyde groups on the surface are collected and designated as MF-CHO-HP ;
    (4) 0.6 g MF-CHO-HP and 1.2 g DAMN are suspended in 60 ml ethanol, sonicated for 10 min and reacted for 4.0 h at 30°C with magnetic stirring, then the product is collected to obtain a hollow porous melamine resin grafted with nitrile group on surface, and named it as MF-CN-HP, finally, 0.6g MF-CN-HP and 6.0g NH2OH·HCl in 60ml of a mixed solution of H2O/ethanol (v/v, 1:9), the pH is adjusted to 9.0 with 1.0 M NaOH, and the resulting mixture is heated in a water bath at 90 °C for 8.0 hours is reacted, then it is centrifuged, rinsed with deionized water and ethanol, and dried at 80°C to obtain MF-AO-HPS.
    [0052] Direct reaction of MF-HP with DAMN and NH 2 OH·HCl gives another adsorbent without grafting of PEA, named MF-nPEA-AO-HPS.
    Performance test:
    The pH value in the environment has a great influence on the adsorption behavior of metal ions. Therefore, the effects of MF-AO-HPS, MF-nPEA-AO-HPS and MF-HP on the adsorption capacity of U(VI) in the range of pH 3.0 to 9.0 are studied. As shown in Figure 8, when the pH is not higher than 7.0, the adsorption capacity of MF-AO-HPS, MF-nPEA-AO-HPS and MF-HP shows a gradual upward trend with increasing pH. After 7.0, its adsorption capacity decreased with increasing pH and the adsorption capacity of MF-AO-HPS was higher than that of MF-nPEA-AO-HPS and MF-HP under all pH conditions.
    The adsorption kinetics of MF-AO-HPS on U(VI) is shown in FIG. From the figure, it can be seen that the adsorption capacity of MF-AO-HPS increased rapidly in the first 30 minutes and reached the maximum adsorption capacity in 60 minutes.
    To investigate the maximum adsorption capacity of MF-AO-HPS, we carried out adsorption equilibrium experiments in the range of U(VI) concentration of 10-500 mg/l and used Langmuir model and Freundlich model to calculate the Adjust adsorption data and investigate the influence of temperature on the adsorption capacity. As shown in Figure 10, in the test temperature range, adsorption capacity increases with increasing temperature.
    Binding of interfering ions and amidoxime groups can have a major impact on the adsorption capacity of MF-AO-HPS for U(VI). Therefore we choose VO<3->, CO<2+>, Ni<+>, Cu<2+>, Zn<2+>, Pb<2><+>, Ca<2+>, Mg<2+ >and Na<+>as a competing ion for U(VI), and the adsorption behavior of the adsorbent in a mixed solution of VO<3->, CO<2><+>, Ni<+>, Cu<2>< +>, Zn<2><+>, Pb<2><+>, Ca<2><+>, Mg<2><+> and Na<+> and U (VI) was examined. As shown in Figure 11, in the presence of numerous interfering ions, MF-AO-HPS still has the highest adsorption capacity for U(VI), which is much larger than the respective adsorption capacity of Vol<3->, CO<2><+ >, Ni<+>, Cu<2><+>, Zn<2+>, Pb<2><+>, Ca<2><+>, Mg<2><+>.
    The adsorption regeneration is an important indicator for evaluating the stability of the adsorbent during recycling. Therefore, we tested the adsorption regeneration performance of MF-AO-HPS over 7 consecutive adsorption-desorption cycles. As shown in Figure 12, after 7 adsorption-desorption cycling experiments, MF-AO-HPS still has a high adsorption capacity, indicating that it has better adsorption regeneration performance and good adsorption ability for U(VI) over the cycle hold.
    Note: The above embodiments are only used to illustrate the present invention and not to limit the technical solutions described in the present invention. Although this specification has detailed the present invention with reference to the above embodiments, those in the art should appreciate that the present invention can still be modified or equivalently substituted, and all technical solutions and improvements not devoid of the spirit and Deviating from the scope of the present invention should be covered by the scope of the claims of the present invention.
    权利要求:
    Claims (10)
    [1]
    1. A process for the preparation of amidoxime-functionalized hollow porous polymeric microspheres using a gas - in - water - emulsion pattern, characterized in that it comprises the following steps:1) production of silica nanoparticles;2) dispersing the silica nanoparticles obtained in step 1) in deionized water to obtain an aqueous silica dispersion, followed by adding melamine to a mixed solution of formaldehyde solution and glutaraldehyde solution under a predetermined temperature condition;adjusting the pH of the mixed solution, followed by stirring and continuing the reaction for a period of time after the solution changes from milky white to clear;followed by adding the aqueous silica dispersion to the reaction with stirring;followed by cooling to a specified temperature and after adjusting pH, conducting a polymerization reaction in a water bath of specified temperature to obtain a product, and finally collecting the product by centrifugation, washing the product with deionized water and ethanol, and drying the product to get a powder sample;adding the powder sample to a hydrofluoric acid solution to obtain an etched product, which is collected by centrifugation, washed with deionized water and ethanol, and centrifuged again to obtain, after drying, a hollow-pore melamine resin, referred to as MF-HP;3) dispersing the MF-HP prepared in step 2) and polyethylenepolyamine, PEA in ethanol to obtain a mixed solution A, followed by sonicating the mixed solution A, allowing the mixed solution A to react in a water bath at a specified temperature under magnetic stirring;centrifuging after the reaction, washing the obtained product with ethanol and collecting again by centrifugation to obtain hollow porous melamine resin polymer microspheres grafted with amino groups on the surface, designated MF-NH2-HP;Followed by adding MF-NH2-HP and glutaraldehyde to ethanol to obtain a mixed solution B, after which the mixed solution B is reacted under magnetic stirring in a water bath at a certain temperature, washing the product after the reaction with each deionized water and ethanol, and centrifugation to obtain hollow porous melamine resin polymer microspheres grafted with aldehyde group on the surface, referred to as MF-CHO-HP;4) Suspending the MF-CHO-HP prepared in step 3) and diaminomaleonitrile DAMN in ethanol to obtain a mixed solution C, followed by sonicating the mixed solution C and allowing the mixed solution C to react under magnetic stirring in a water bath at a certain temperature, followed by centrifugation to obtain a hollow-pore melamine resin grafted with nitrile groups on the surface, called MF-CN-HP, and finally adding ethanol to deionized water to obtain a mixture of ethanol and water , adding MF-CN-HP and hydroxylamine hydrochloride followed by pH adjustment and placing the mixture to react in water bath at a predetermined temperature; After the reaction, centrifuge to collect the product, wash with deionized water and ethanol, and dry at drying temperature to obtain amidoxime-functionalized hollow porous melamine resin microspheres, designated MF-AO-HPS.
    [2]
    2. A method for preparing amidoxime-functionalized hollow porous polymer microspheres using a gas - in - water - emulsion pattern according to claim 1, wherein the predetermined temperature condition in steps 2) is 80 to 90 ° C, wherein the amount ratio of melamine, the mixed Formaldehyde and glutaraldehyde solution and the silica dispersion is 1.0-2.0g: 2.0-4.0ml: 5.0-15ml, where the volume fraction of the formaldehyde solution is 37%, the volume fraction of the glutaraldehyde solution is 25% is, the concentration of the aqueous silica dispersion is 10% by weight.
    [3]
    3. A process for the preparation of amidoxime-functionalized hollow porous polymeric microspheres using a gas - in - water - emulsion pattern according to claim 1, characterized in that the adjustment of the pH value in step 2) consists in using a Na2CO3 solution to adjust the pH to 9.0-10.0, the concentration of the Na2CO3 solution is 2.0 M, the stirring condition is 1200 to 1600 rpm, the period of continued reaction is 3.0 to 5.0 min, the reaction time after of the addition of the aqueous silica dispersion is 10 to 30 minutes.
    [4]
    4. A method of preparing amidoxime-functionalized hollow porous polymeric microspheres using a gas-in-water emulsion pattern according to claim 1, characterized in that the temperature is reduced to the specified temperature of 30-50°C by the cooling in step 2). wherein the process of adjusting the pH consists in adding dropwise 2.0 M HCl to adjust pH to 5.0-6.0, the reaction time after adjusting the pH being 10-30 min; wherein the water bath condition is the temperature of 30-50 °C, the polymerization reaction time is 3.0-5.0 h, the volume concentration of the hydrofluoric acid solution is 2%, the drying temperature is uniformly 60-80 °C.
    [5]
    5. A process for the preparation of amidoxime-functionalized hollow porous polymer microspheres using a gas - in - water - emulsion pattern according to claim 1, characterized in that the amount ratio of MF-HP, polyethylene polyamine and ethanol in step 3) 0.3-0. 5 mg: 3.0-5.0 g: 40-60 ml.
    [6]
    6. A method for preparing amidoxime-functionalized hollow porous polymer microspheres using a gas - in - water - emulsion pattern according to claim 1, characterized in that the ultrasonic treatment time in step 3) is 5.0 to 10 min, the temperature of the water bath of the mixed solution A is 30 to 40°C and the reaction time is 8.0 to 16 hours.
    [7]
    7. A method for preparing amidoxime-functionalized hollow porous polymer microspheres using a gas - in - water - emulsion pattern according to claim 1, characterized in that the quantitative ratio of MF-NH 2 -HP, glutaraldehyde and ethanol in step 3) 0.2 -0.4mg: 8.0-12ml: 30-50ml, the volume fraction of glutaraldehyde is 25%, the temperature of the water bath of the mixed solution B in step 3) is 20 to 30°C, and the reaction time is 8 0-16 hours.
    [8]
    8. A method for preparing amidoxime-functionalized hollow porous polymer microspheres using a gas - in - water - emulsion pattern according to claim 1, characterized in that the amount ratio of MF-CHO-HP, diaminomaleonitrile and ethanol in step 4) 0.2- 0.6 mg: 0.4-1.2 mg: 40-60 ml, the specified temperature of the water bath is 20-30°C and the reaction time is 2.0-4.0 hours.
    [9]
    9. A process for the preparation of amidoxime-functionalized hollow porous polymeric microspheres using a gas - in - water - emulsion pattern according to claim 1, characterized in that the volume ratio of ethanol and water in step 4) is 9: 1, the amount ratio of MF -CN-HP, Hydroxylamino hydrochloride, Mixture of ethanol F and water 0.2-0.6 mg: 2.0-6.0 g : 40-60 ml, where the pH adjustment in step 4) is that adjust the pH to 8.0-9.0 with 1.0 M NaOH, the predetermined temperature of the water bath is 70-90 °C, and the reaction time of the water bath is 4.0-8.0 h, the drying temperature is 60-80 °C.
    [10]
    10. Use of an amidoxime-functionalized hollow porous polymeric microsphere prepared according to any one of claims 1 to 9 for the selective adsorption and separation of hexavalent uranium in solution.
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    同族专利:
    公开号 | 公开日
    GB202018087D0|2020-12-30|
    GB2590792A|2021-07-07|
    CN110961085A|2020-04-07|
    JP2022511183A|2022-01-31|
    CN110961085B|2021-05-25|
    WO2021093306A1|2021-05-20|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    JP2006026588A|2004-07-20|2006-02-02|Japan Atom Energy Res Inst|Method for recovering and removing useful or harmful metal dissolved in hot-spring water|
    JPWO2012036034A1|2010-09-14|2014-02-03|国立大学法人大阪大学|Amidoxime-modified polyacrylonitrile porous material|
    CN105817213B|2016-05-23|2018-04-03|大连工业大学|A kind of application of adsorbent based on hollow mesoporous silicon oxide and preparation method thereof and recovery gold|
    CN106902747B|2017-03-29|2019-09-13|东华理工大学|A kind of amidoxim mesoporous silicon dioxide micro-sphere adsorbent and preparation method thereof|
    CN108160058B|2018-01-15|2020-11-03|大连工业大学|Magnetizable hollow mesoporous/microporous composite nano adsorbent, preparation method thereof and application of magnetizable hollow mesoporous/microporous composite nano adsorbent in adsorption of heavy metal ions|
    CN110961085B|2019-11-11|2021-05-25|江苏大学|By using CO2Method for preparing amidoxime functionalized hollow porous polymer microspheres for emulsion template|CN110961085B|2019-11-11|2021-05-25|江苏大学|By using CO2Method for preparing amidoxime functionalized hollow porous polymer microspheres for emulsion template|
    CN113060750A|2021-03-17|2021-07-02|电子科技大学|Preparation method of mesoporous ionic compound for extracting uranium from seawater|
    法律状态:
    2021-12-15| PL| Patent ceased|
    优先权:
    申请号 | 申请日 | 专利标题
    CN201911092454.5A|CN110961085B|2019-11-11|2019-11-11|By using CO2Method for preparing amidoxime functionalized hollow porous polymer microspheres for emulsion template|
    PCT/CN2020/092492|WO2021093306A1|2019-11-11|2020-05-27|Method for preparing amidoxime functionalized hollow porous polymer microsphere by using co2 as emulsion template|
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