CN103709342B - A kind of preparation method of magnetic cadmium ion surface imprinted polymer - Google Patents

Abstract

The invention is a preparation method of a magnetic cadmium ion surface imprinted polymer. In the method, the "co-precipitation method" and the "sol-gel method" are used to synthesize magnetic Fe ₃ O ₄ SiO ₂ microspheres, and the acid treatment is used to improve its Surface hydroxyl content; then use the "two-step method" to introduce polymerizable double bonds to the surface of Fe ₃ O ₄ SiO ₂ microspheres, that is, first use aminosilane coupling agent to graft amino groups to the surface of microspheres, and then use acid anhydride and amino groups to The reaction generates double bonds; finally, Fe ₃ O ₄ SiO ₂ microspheres are used as the carrier, Cd(II) is used as the template, ethylene glycol dimethacrylate is used as the cross-linking agent, and methacrylic acid and salicylaldoxime are used as monomers for polymerization After the reaction, the template Cd (II) is washed away to obtain a polymer layer in which a large number of Cd (II) imprinted holes are distributed on the surface of the Fe ₃ O ₄ SiO ₂ microspheres. The magnetic cadmium ion surface imprinted polymer of the invention can be used for the separation and removal of cadmium ions.

Description

A kind of preparation method of magnetic cadmium ion surface imprinted polymer

technical field

The invention relates to a preparation method of a magnetic cadmium ion surface imprinted polymer, in particular to a magnetic cadmium ion surface imprinted polymer with a core-shell structure.

Background technique

Cadmium is mainly used in the manufacture of alloys, atomic reactor (neutron absorption) control rods, electroplating, and rechargeable batteries. Cadmium compounds have been widely used in the manufacture of (yellow) pigments, plastic stabilizers, (TV image tube) phosphors, and insecticides. Agents, fungicides, paints, etc. With the continuous development of modern industry, a large amount of cadmium-containing wastewater is discharged into rivers, causing cadmium pollution. When the environment is polluted by cadmium, cadmium can be enriched in organisms and enter the human body through the food chain to cause chronic poisoning. After cadmium is absorbed by the human body, it forms cadmium-sulfur protein in the body, which selectively accumulates in the liver and kidney. This affects the normal function of the enzyme system in the liver and kidney organs, and hinders the growth and metabolism of bones, resulting in loose bones, atrophy, and deformation. At present, the common treatment methods include ion exchange method, membrane separation method, chemical precipitation method and adsorption method, etc., and the adsorption method is considered to be an efficient and economical method. The specific recognition ability has been extensively studied.

Molecular imprinting technology specifically refers to using the target molecule as a template, combining structurally complementary functionalized polymer monomers with the template molecule through covalent or non-covalent bonds, and adding a cross-linking agent for polymerization reaction. After the reaction is completed, the The template molecules are eluted to form a type of rigid polymer with fixed hole size and shape and a certain arrangement. The corresponding cross-linked polymers are molecularly imprinted polymers (Molecular Imprinting Polymers, referred to as MIPs). If ions are used as templates, the technology is called ion imprinting technology, and the products prepared are ion imprinted polymers (IonicImprintPolymers, referred to as IIPs). Ion-imprinted polymers are similar to molecularly imprinted polymers, except that the recognition objects are ions, and almost maintain all the advantages of molecular imprinting. Traditional methods for synthesizing imprinted polymers include bulk polymerization, suspension polymerization, and precipitation polymerization, but these methods have disadvantages such as low reloading ability, slow adsorption rate, and incomplete removal of templates. However, the surface imprinting developed in recent years can not only overcome these shortcomings, but also has the advantages of high selectivity to target ions, low exchange resistance, and high adsorption capacity. Surface imprinting refers to a technique in which a polymerization reaction occurs on the surface of a solid substrate, so that the imprinted sites are distributed on the surface and outer layer of the solid substrate. Surface imprinting technology can use silica gel, organic polymer carrier, and capillary as substrate for polymerization reaction. In particular, the imprinted material with recognition sites on the surface of silica gel not only has the function of molecular imprinting, but also has good mechanical and thermal stability, high adsorption selectivity, good monodispersity, and uniform particle size distribution. Therefore, based on Surface imprinting technology on silica gel surface has become a research hotspot. The process of preparing imprinted polymers by traditional methods involves filtration and centrifugation, which are complicated operations, but magnetically imprinted polymers (M-IIP) are replaced by magnetic separation, which is easy to operate and environmentally friendly. At the same time, magnetically imprinted polymers also have the advantages of controllable size, uniform binding sites, and stable physical and chemical properties. Chinese patent 201010139199.8 adopts the sol-gel method, mercaptopropyltriethoxysilane is used as the functional monomer, and the magnetic microspheres imprinted with cadmium ions are made after deposition on the surface of Fe ₃ O ₄ . Chinese patent 201210296056.7 first prepares Fe ₃ O ₄ nanoparticles by hydrothermal method, then prepares Fe ₃ O ₄ SiO ₂ wrapped in silicon layer by hydrolysis of tetraethoxysilane, and finally uses nitrogen-containing silylating reagent as functional monomer , hexadecyltrimethylammonium bromide was used as a pore-forming agent, and tetraethoxysilane was used as a cross-linking agent to prepare a porous copper ion imprinted layer by depositing on the surface of Fe ₃ O ₄ SiO ₂ .

The above methods usually have the following problems: (1) The general synthetic magnetic imprinting uses Fe ₃ O ₄ as the core, wraps a layer of SiO ₂ on the outside, and then uses the hydroxyl groups on the surface of SiO ₂ to directly graft functional monomers, Or carry out silanization and related follow-up reactions to synthesize imprinted materials. However, the content of hydroxyl groups on the surface of _SiO2 is limited, which will affect the grafting rate of functional monomers or the effect of surface modification of silane coupling agents. (2) Grafting polymerizable double bonds on the outer layer of the carrier, mostly using γ-(methacryloyloxy)propyltrimethoxysilane to introduce double bonds (Zhang Shuanhong, Sun Changmei, Qu Rongjun. Surface molecules (ions) Advances in the preparation and performance of imprinted silica gel/polymer. Polymer Bulletin, 2010(4):17-29.), but it is thermally unstable, under conventional silanization conditions (110°C toluene as solvent for reflux ) will undergo thermal polymerization, but if the temperature is lowered, the efficiency of the introduction of double bonds will be reduced. Gao et al. (DamingGao, Zhongping Zhang, Minghong Wu, et al., A surface functional monomer-directing strategy for highly dense imprinting of TNTat surface of silicon ananoparticles, J. Am. Chem. Soc., 2007, 129: 7859-7866.) explored a new method for preparing silica gel surface imprinted materials. They first aminated the silica gel with γ-aminopropyltriethoxysilane on the surface of the silica gel, and then carried out acrylation to introduce double bonds. Using 2,4,6-trinitrotoluene (TNT) as a template molecule, dimethyl Ethylene glycol acrylate was used as a cross-linking agent to prepare polyacrylamide-coated silica core-shell surface imprinted materials, and the adsorption rate was significantly improved. However, in the process of introducing double bonds, nitrogen protection is required, and potassium carbonate is used as a catalyst, so the reaction is more complicated. (3) In the selection of monomers, most literatures use a single functional monomer. For example, methacrylic acid has become one of the most commonly used functional monomers for preparing metal ion polymers because it contains unsaturated double bonds and carboxyl groups coordinated with metal ions. However, the rigidity of methacrylic acid is not good, and the rigidity of the imprinted holes synthesized is small, which affects the reusability. (4) In the reported literature and patents, the adsorbent is often used alone for the adsorption of trace or trace ions, which limits the scope of use of the adsorbent. Therefore, it is necessary to develop adsorbents with a wide range of applications.

Contents of the invention

The present invention aims to solve the above-mentioned technical problems existing in the prior art, and provides a magnetic cadmium ion surface imprinted polymer with high selectivity for separating and removing trace or even trace amounts of cadmium ions in water. In this method, magnetic Fe ₃ O ₄ SiO ₂ microspheres were first synthesized by "co-precipitation method" and "sol-gel method", and treated with acid to increase their surface hydroxyl content; Introduce to the surface of Fe ₃ O ₄ SiO ₂ microspheres, that is, use aminosilane coupling agent to graft amino groups to the surface of microspheres, and then use the reaction of acid anhydride and amino groups to form double bonds; finally, Fe ₃ O ₄ SiO ₂ microspheres As a carrier, Cd(II) as a template, ethylene glycol dimethacrylate as a crosslinking agent, methacrylic acid and salicylaldoxime as monomers for polymerization reaction, after the reaction, the template Cd(II) is washed away to obtain Fe A polymer layer with a large number of Cd(II) imprinted holes distributed on the surface of ₃ O ₄ SiO ₂ microspheres.

Technical scheme of the present invention is:

A preparation method for a magnetic cadmium ion surface imprinted polymer, comprising the steps of:

(1) Synthesis of Fe ₃ O ₄ : Dissolve FeSO ₄ ·7H ₂ O and FeCl ₃ ·6H ₂ O in ultrapure water, add ammonia water under the condition of flowing N ₂ , stir at 60-80°C for 1-2 hours, Add citric acid to react for 60-90 minutes, magnetically separate after cooling, collect the black deposit, remove the supernatant, wash until neutral, and then vacuum-dry to obtain _Fe3O4 nanoparticles; wherein, the mass ratio of each substance in the reaction is _{FeSO 4} 7H ₂ O: FeCl ₃ 6H ₂ O: ammonia water: citric acid: ultrapure water = 5: 8 ~ 10: 15 ~ 30: 0.5 ~ 1: 150 ~ 200;

(2) Synthesis of Fe ₃ O ₄ SiO ₂ microspheres: ultrasonically disperse Fe ₃ O ₄ nanoparticles in a mixed solution of alcohol and distilled water, add ammonia water and tetraethyl orthosilicate, react at room temperature for 10-24 hours, magnetically separate the product, collect and deposit matter, remove the upper layer solution, wash and dry to obtain Fe ₃ O ₄ SiO ₂ microspheres; wherein, the mass ratio of each substance in the reaction is Fe ₃ O ₄ nanoparticles: alcohol: distilled water: ammonia water: ethyl orthosilicate=0.5 ～2.5: 50～100: 10～50: 2～5: 3～10;

(3) Activation of Fe ₃ O ₄ SiO ₂ microspheres: Add Fe ₃ O ₄ SiO ₂ microspheres into the acidic solution, react at 80-110°C for 5-10 hours, collect the sediment after magnetic separation of the product, remove the upper solution, Washing and drying to obtain activated Fe ₃ O ₄ SiO ₂ microspheres; wherein, the mass ratio of each substance in the reaction is Fe ₃ O ₄ SiO ₂ microspheres:acid solution=1:2～20;

(4) Synthesis of aminated Fe ₃ O ₄ SiO ₂ (Fe ₃ O ₄ SiO ₂ -A): Activated Fe ₃ O ₄ SiO ₂ microspheres were added to toluene for ultrasonication, then aminosilane coupling agent was added, nitrogen atmosphere , adjust the pH to 10-11, react at 80-110°C for 5-12 hours, magnetically separate the product, collect the sediment, remove the upper solution, wash and dry to obtain Fe ₃ O ₄ SiO ₂ -A; The mass ratio of substances is activated Fe ₃ O ₄ SiO ₂ microspheres:aminosilane coupling agent:toluene=2:10～15:30～50;

(5) Synthesis of carboxylated Fe ₃ O ₄ SiO ₂ (Fe ₃ O ₄ SiO ₂ -AB): Fe ₃ O ₄ SiO ₂ -A and acid anhydride were added to N,N'-dimethylformamide, and the mixture was React at 25-50°C for 10-24 hours, magnetically separate the product, collect the sediment, remove the upper layer solution, wash and dry to obtain Fe ₃ O ₄ SiO ₂ -AB; wherein, the mass ratio of each substance in the reaction is Fe ₃ O ₄ SiO ₂ -A: acid anhydride: N,N'-dimethylformamide = 1～2: 2～5: 40～50;

(6) Preparation of magnetic imprinted materials: Add inorganic cadmium salt, methacrylic acid, and salicylaldoxime to methanol, stir overnight at room temperature, then add Fe ₃ O ₄ SiO ₂ -AB, EGDMA and AIBN, and place under N ₂ protection at 60 After reacting at ℃ for 12-24 hours, the product was magnetically separated and washed with methanol, and then the Cd ²⁺ was eluted with an acidic solution until no Cd ²⁺ was detected in the filtrate to obtain a magnetic cadmium ion-imprinted polymer (Cd-M-IIP); , the mass ratio of each substance in the reaction is cadmium salt: Fe ₃ O ₄ SiO ₂ -AB: methacrylic acid: salicylaldoxime: EGDMA: AIBN: methanol = 0.1～0.5: 0.2～1: 0.2～0.5: 0.2～0.5: 1～2: 0.1～0.2: 30～50.

The alcohol in the step (2) is specifically one of methanol, ethanol and isopropanol.

The acid solution in the steps (3) and (6) is specifically one of H ₂ SO ₄ , HNO ₃ , HCl and H ₃ PO ₄ solutions, and the mass concentration of the acid solution is 5-20%.

The reagent for adjusting pH in the step (4) is specifically one of triethylamine, ammonia water (25-28% mass concentration), NaOH (5% mass concentration) and KOH (5% mass concentration).

The aminosilane coupling agent in the step (4) is specifically γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl)-γ-aminopropyl One of triethoxysilane, anilinomethyltriethoxysilane and aminoethylaminopropyltrimethoxysilane.

The acid anhydride in the step (5) is specifically one of succinic anhydride, maleic anhydride, phthalic anhydride and trimellitic anhydride.

The inorganic cadmium salt in the step (6) is specifically one of Cd(NO ₃ ) ₂ , Cd(Ac) ₂ , CdCl ₂ and CdSO ₄ .

The concentration of ammonia water in the steps (1) and (2) is both 25-28% by mass.

Compared with prior art, advantage of the present invention is: _1. with acid activation Fe ₃ O ₄ SiO After microsphere, improved its surface hydroxyl content, strengthened the modification strength of silane coupling agent as embodiment 1 ( In the experiment, we used the same method to graft aminosilane coupling agent on the surface of Fe ₃ O ₄ SiO ₂ microspheres, and the content of amino groups grafted on the surface of unactivated microspheres was 1.13 mmol by acid-base back titration method. /g, the amino group content on the surface of the activated microspheres was 1.58mmol/g); 2. The "two-step method" successfully avoided the direct use of γ-(methacryloyloxy)propyltrimethoxysilane on the microspheres The introduction of polymerizable double bonds on the surface improves the efficiency of the introduction of double bonds; 3. The imprinted material synthesized from methacrylic acid and salicylaldoxime significantly improves the adsorption capacity. The saturated adsorption capacity of the imprinted polymer synthesized by the monomer is about 17mg/g higher; 4. the imprinted polymer has good magnetic properties, so it is convenient for post-processing, as the magnetic properties of the final product in Example 1 are 0.96emu/g, when applied When an external magnetic field is applied, the separation from the sample matrix can be achieved quickly (as shown in Figure 4c); 5. This method prepares nano-scale particles with a large specific surface area (this can be confirmed from the corresponding electron microscope images, and the increase in the specific surface area is definitely beneficial The increase of surface adsorption sites improves the adsorption performance. Adsorption experiments have confirmed that the adsorption performance of the obtained material is relatively good. The saturated adsorption capacity can reach 58.83mg/g at 291-293K, and the later thermodynamic experiments confirmed that The increase of temperature is conducive to the increase of adsorption capacity, and the adsorption capacity of cadmium is also larger; 6. The magnetic cadmium ion surface imprinted polymer synthesized by this method can be used for the separation and removal of cadmium ions.

Description of drawings

Fig. 1a is Example 1 of the present invention Fe ₃ O ₄ nanoparticles (A), Fe ₃ O ₄ SiO ₂ microspheres (B), activated Fe ₃ O ₄ SiO ₂ microspheres (C), aminated Fe ₃ O ₄ Infrared spectra of SiO ₂ microspheres (D) and carboxylated Fe ₃ O ₄ SiO ₂ microspheres (E);

Figure 1b is the infrared spectrum of the magnetic cadmium ion surface imprinted polymer (A) and the magnetic non-imprinted polymer (B);

Fig. 2 is a scanning electron microscope image of the magnetic cadmium ion surface imprinted polymer (Fig. 2a) and the magnetic non-imprinted polymer (Fig. 2b) in Example 1 of the present invention;

Fig. 3 is the magnetic hysteresis loop diagram of Fe ₃ O ₄ nanoparticles and Fe ₃ O ₄ SiO ₂ microspheres (Fig. 3a), the magnetic cadmium ion surface imprinted polymer (Fig. 3b) in Example 1 of the present invention, and the magnetic separation effect Comparison photo (Fig. 3c);

Fig. 4 is the adsorption capacity figure of embodiment 1 magnetic cadmium ion surface imprinted polymer in the present invention at different pHs;

Fig. 5 is the kinetic curve figure of embodiment 1 magnetic cadmium ion surface imprinted polymer in the present invention;

Fig. 6 is the saturated adsorption capacity figure of embodiment 1 magnetic cadmium ion surface imprinted polymer and magnetic non-imprinted polymer in the present invention;

Fig. 7 is a diagram of the adsorption capacity of the magnetic cadmium ion surface-imprinted polymer in Example 1 of the present invention at 25-45°C.

detailed description

Example 1

(1) Synthesis of Fe ₃ O ₄ : 2.78g FeSO ₄ 7H ₂ O and 4.73g FeCl ₃ 6H ₂ O were dissolved in 100g ultrapure water (ultrapure water is to remove the conductive medium in the water almost completely, and keep the water inseparable. The decomposed colloidal substances, gases and organic substances are all removed to a very low level of water. The resistivity is greater than 18MΩ*cm, or close to the limit value of 18.3MΩ*cm.), under the condition of N ₂ , under vigorous stirring (stepless speed regulation Booster stirrer, set the speed gear to 2.5 (DW-Ⅱ type, Gongyi Yuhua Instrument Co., Ltd.), add 10g of ammonia water with a concentration of 25% to 28% by mass, react at 60°C for 1h, add 0.5g of lemon Acid reaction for 60 minutes, magnetic separation after cooling, collecting black deposits, removing the supernatant, washing with ultrapure water until neutral, then washing with 50mL absolute ethanol for 2 to ₃ times, and vacuum drying to obtain _Fe3O4 nanoparticles; ( 2) Synthesis of Fe ₃ O ₄ SiO ₂ microspheres: ultrasonically disperse 1g of Fe ₃ O ₄ nanoparticles in a mixed solution consisting of 79g of absolute ethanol and 20g of distilled water, add 4g of ammonia water and 7g of ethyl orthosilicate, and react at room temperature for 10h , the product was magnetically separated, the sediment was collected, the upper layer solution was removed, washed 2 to 3 times with 50mL distilled water and 50mL absolute ethanol, and then dried. After vacuum drying, Fe ₃ O ₄ SiO ₂ microspheres were obtained; (3) Fe ₃ O ₄ Activation of SiO ₂ microspheres: Add 10g Fe ₃ O ₄ SiO ₂ microspheres to 100g of 10% hydrochloric acid solution, react at 110°C for 5h, magnetically separate the product and collect the sediment, remove the upper layer solution, and wash with distilled water until medium properties, washed with 50mL absolute ethanol for 2 to 3 times, and dried to obtain activated Fe ₃ O ₄ SiO ₂ microspheres; (4) Synthesis of aminated Fe ₃ O ₄ SiO ₂ (Fe ₃ O ₄ SiO ₂ -A): Add 2g of activated Fe ₃ O ₄ SiO ₂ microspheres into 35g of toluene for ultrasonic dispersion, then add 10g of γ-aminopropyltriethoxysilane, add triethylamine under nitrogen atmosphere to adjust pH≈10, and react at 110°C for 10h. Magnetically separate the product, collect the sediment, remove the upper layer solution, wash with 50mL toluene and 50mL absolute ethanol for 2 to 3 times, and then dry to obtain Fe ₃ O ₄ SiO ₂ -A; (5) Carboxylation of Fe ₃ O ₄ SiO ₂ Synthesis of (Fe ₃ O ₄ SiO ₂ -AB): 1g Fe ₃ O ₄ SiO ₂ -A and 2g maleic anhydride were added to 45g N,N'-dimethylformamide, and the mixture was reacted at 25°C for 24h , the product was magnetically separated, the sediment was collected, the upper solution was removed, washed 2 to 3 times with 50mL DMF and 50mL absolute ethanol, and then dried to obtain Fe ₃ O ₄ SiO ₂ -AB; (6) Preparation of magnetic imprinted material : Add 0.4g cadmium chloride, 0.3g methacrylic acid, 0.3g salicylaldoxime to 40g methanol, stir overnight at room temperature, then add _{0.5gFe3O4SiO2 -} AB, 2.0gEGDMA and _0.11gAIBN , under _N2 protection React at 60°C for 24 hours, magnetically separate the product and wash 2 to 3 times with 50 mL of methanol to obtain a magnetic cadmium ion surface imprinted polymer without eluted template, and then use 15% hydrochloric acid to elute Cd ²⁺ into the filtrate After Cd ²⁺ could not be detected, a magnetic cadmium ion surface-imprinted polymer (Cd-M-IIP) was obtained.

In addition, for the preparation of the magnetic non-imprinted polymer (M-NIIP) used for the control, except that no cadmium salt was added in step (6), the other operations were the same as the preparation of Cd-M-IIP, and finally the magnetic non-imprinted polymer was obtained.

As shown in Figure 1a, the order is _Fe3O4 nanoparticles ( _A ), (B _{) Fe3O4SiO2} microspheres (B), activated _Fe3O4SiO2 microspheres ₍ C ₎ , _{aminated Fe3} Infrared spectra of O ₄ SiO ₂ microspheres (D) and carboxylated Fe ₃ O ₄ SiO ₂ microspheres (E). The Fe-O vibration absorption peak appeared at 578cm- ¹ in A; the Si-O-Si asymmetric stretching vibration absorption peak appeared at 1090cm ^-1 in B, and the Si-O bending vibration absorption peak appeared at 798cm ^-1 . The vibration absorption peak of Si-OH appeared at 952cm ^-1 , which proved that SiO ₂ was successfully wrapped on Fe ₃ O ₄ ; Fe ₃ O ₄ SiO ₂ microspheres were activated by HCl to obtain C, and C in 3430～3450cm ^-1 could It can be seen that the -OH peak is significantly enhanced, which paves the way for the subsequent reactions; the activated Fe ₃ O ₄ SiO ₂ microspheres are treated with silane coupling agent APS to obtain D, and D is at 2930cm ^-1 and 2987cm ^-1 The saturated CH bond stretching vibration absorption peak appeared, and the deformation vibration absorption peak of the primary amine NH bond appeared at 1500～1600cm ^-1 , indicating that APS was successfully bonded on the surface of Fe ₃ O ₄ SiO ₂ microspheres; at 1715cm ^-1 in E The C=O stretching vibration absorption peak appeared, and the C=C stretching vibration absorption peak appeared at 1576cm ^-1 , and the maleic anhydride on the surface reacted successfully with the amino groups on the Fe ₃ O ₄ SiO ₂ microspheres. The infrared spectra of the magnetic cadmium ion surface-imprinted polymer (A) and the magnetic non-imprinted polymer (B) in Figure 1b show that the main characteristic peaks appear in the same shape, indicating that Cd ²⁺ is basically eluted cleanly. The C=O absorption peak appeared at 1730cm ^-1 , the alkyl CH bond stretching vibration absorption peak appeared at 2988cm ^-1 , the asymmetric and symmetric stretching vibration absorption peaks of COC appeared at 1250cm ^-1 and 1156cm ^-1 , and the asymmetric and symmetric stretching vibration absorption peaks of COC appeared at 1457cm ^-1 and The C=N absorption peak at 1387cm ^-1 proved that the grafting of MAA and SALO was successful. Among them, 1637cm ^-1 is the incompletely reacted C=C vibrational absorption peak; Figure 2a and 2b are the scanning electron microscope images of the magnetic cadmium ion surface imprinted polymer and the magnetic non-imprinted polymer respectively, it can be seen that there are many small particles gathered in the Together, this morphological change should be attributed to the polymer grafting on the surface of Fe ₃ O ₄ SiO ₂ microspheres, and the surface of Cd-M-IIP is rougher than that of M-NIIP, because after the template elution, leaving It is caused by many imprinted holes. The imprinting process makes the surface rough, which not only increases the adsorption surface area, but also increases the number of binding sites, which is conducive to improving its adsorption capacity and improving the ability to identify template ions; Figure 3a is Fe The hysteresis loop diagrams of ₃ O ₄ nanoparticles and Fe ₃ O ₄ SiO ₂ microspheres. Figure 3b is the hysteresis loop diagram of the magnetic cadmium ion surface imprinted polymer. The saturation magnetization of the three are 85.11﹑34.10 respectively and 0.96emu/g, Figure 3c is the state of the magnetic cadmium ion surface imprinted polymer before and after applying an external magnetic field, it can be seen that the imprinted material can be quickly separated when an external magnetic field is applied; Figure 4 shows the magnetic cadmium ion under different pH conditions The adsorption capacity graph of the surface imprinted polymer shows that at pH 1.0-6.5, as the pH increases, the adsorption capacity also increases gradually, and reaches the maximum near pH 6.5. When the pH>6.5, the adsorption capacity drops sharply again; Figure 5 is the kinetic curve of the magnetic cadmium ion surface imprinted polymer, it can be seen that the adsorption rate of Cd-M-IIP to Cd ²⁺ is relatively fast, and it can be reached within 50 minutes. The adsorption balance fully shows the characteristics of rapid adsorption of surface imprinting technology; Figure 6 is the saturated adsorption capacity diagram of magnetic cadmium ion surface imprinted polymer and magnetic non-imprinted polymer, it can be seen that the saturated adsorption capacity is 58.83 and 33.82mg/g respectively (T=291～293K); Figure 7 is the adsorption capacity diagram of the magnetic cadmium ion surface imprinted polymer at 25～45°C, it can be seen that a slightly higher temperature is conducive to the increase of the adsorption capacity.

Example 2

(1) Synthesis of Fe ₃ O ₄ : 5.56g FeSO ₄ 7H ₂ O and 9.46g FeCl ₃ 6H ₂ O were dissolved in 200g of ultrapure water, and under the condition of passing through N ₂ , add 20g of FeSO 4 7H 2 O and 25% by weight under vigorous stirring. ～28% ammonia water, react at 60°C for 1 hour, add 1g of citric acid and react for 90 minutes, magnetically separate after cooling, collect the black sediment, remove the supernatant, wash with ultrapure water until neutral, then wash with 50mL absolute ethanol for 2～ 3 times, vacuum-dried to obtain Fe ₃ O ₄ nanoparticles; (2) Synthesis of Fe ₃ O ₄ SiO ₂ microspheres: 2g Fe ₃ O ₄ nanoparticles were ultrasonically dispersed in a mixed solution consisting of 158g methanol and 40g distilled water, and 8g Ammonia water and 14g tetraethyl orthosilicate were reacted at room temperature for 24 hours, the product was magnetically separated, the sediment was collected, the upper layer solution was removed, washed 2-3 times with 50mL distilled water and 50mL absolute ethanol, and then dried to obtain Fe ₃ O ₄ SiO ₂ Microspheres; (3) Activation of Fe ₃ O ₄ SiO ₂ microspheres: Add 5g of Fe ₃ O ₄ SiO ₂ microspheres to 100g of 20% nitric acid solution, react at 100°C for 6h, magnetically separate the product, collect the sediment, Remove the upper layer solution, wash with distilled water until neutral, wash with 50mL absolute ethanol for 2 to 3 times, and obtain activated Fe ₃ O ₄ SiO ₂ microspheres after drying; (4) Aminated Fe ₃ O ₄ SiO ₂ (Fe ₃ O ₄ SiO ₂ -A) Synthesis: Add 4g of activated Fe ₃ O ₄ SiO ₂ microspheres to 70g of toluene for ultrasonication, then add 20g of γ-aminopropyltrimethoxysilane, add appropriate amount of ammonia water, adjust pH ≈ 10, nitrogen atmosphere, React at 110°C for 10 hours, magnetically separate the product, collect the sediment, remove the upper layer solution, wash with 50mL toluene and 50mL absolute ethanol for 2 to 3 times, and then dry to obtain Fe ₃ O ₄ SiO ₂ -A; (5) Carboxyl Synthesis of Fe ₃ O ₄ SiO ₂ (Fe ₃ O ₄ SiO ₂ -AB): 2g of Fe ₃ O ₄ SiO ₂ -A and 4g of succinic anhydride were added to 90g of N,N'-dimethylformamide, the mixture was at 30 React at ℃ for 10 hours, magnetically separate the product, collect the sediment, remove the upper layer solution, wash with 50mL DMF and 50mL absolute ethanol for 2 to 3 times, and then dry to obtain Fe ₃ O ₄ SiO ₂ -AB; (6) Magnetic imprinted material Preparation: Add 0.5g cadmium nitrate, 0.5g methacrylic acid, 0.5g salicylaldoxime to 80g methanol, stir overnight at room temperature, then add 1gFe ₃ O ₄ SiO ₂ -AB, 3gEGDMA and 0.15gAIBN, under the protection of N ₂ React at 60°C for 12 hours, magnetically separate the product and wash 2 to 3 times with 50 mL of methanol, then use a mass concentration of 20% After elution of Cd ²⁺ with nitric acid until no Cd ²⁺ was detected in the filtrate, the magnetic cadmium ion surface-imprinted polymer (Cd-M-IIP) was obtained. The characterization and analysis results of the obtained magnetic imprinted material are the same as those in Example 1.

Example 3

(1) Synthesis of Fe ₃ O ₄ : 2.78g FeSO ₄ 7H ₂ O and 4.73g FeCl ₃ 6H ₂ O were dissolved in 100g of ultra-pure water, and under N ₂ conditions, 15g of mass percent was added under vigorous stirring to reach a concentration of 25 ～28% ammonia water, react at 70°C for 1 hour, add 0.5g citric acid to react for 60 minutes, magnetically separate after cooling, collect the black sediment, remove the supernatant, wash with ultrapure water until neutral, then wash with 50mL absolute ethanol for 2 ~3 times, vacuum drying to obtain Fe ₃ O ₄ nanoparticles; (2) Synthesis of Fe ₃ O ₄ SiO ₂ microspheres: 1g Fe ₃ O ₄ nanoparticles were ultrasonically dispersed in a mixed solution consisting of 79g absolute ethanol and 20g distilled water , add 3g of ammonia water and 8g of ethyl orthosilicate, react at room temperature for 12h, magnetically separate the product, collect the sediment, remove the upper solution, wash with 50mL of distilled water and 50mL of absolute ethanol for 2 to ₃ times, and then dry to obtain Fe3O ₄ SiO ₂ microspheres; (3) Activation of Fe ₃ O ₄ SiO ₂ microspheres: Add 10g of Fe ₃ O ₄ SiO ₂ microspheres to 100g of sulfuric acid solution with a mass concentration of 10%, react at 110°C for 6h, and magnetically separate the product. Collect the sediment, remove the upper layer solution, wash with distilled water until neutral, wash with 50mL absolute ethanol for 2 to 3 times, and dry to obtain activated Fe ₃ O ₄ SiO ₂ microspheres; (4) Amination of Fe ₃ O ₄ SiO ₂ Synthesis of (Fe ₃ O ₄ SiO ₂ -A): 2 g of activated Fe ₃ O ₄ SiO ₂ microspheres were added to 35 g of toluene for sonication, and then 10 g of N-β(aminoethyl)-γ-aminopropyltriethoxy Silane, add KOH solution with a mass concentration of 5% to adjust pH ≈ 10, nitrogen atmosphere, react at 100°C for 5 hours, magnetically separate the product, collect the sediment, remove the upper solution, and wash with 50mL toluene and 50mL absolute ethanol for 2~ After drying for 3 times, Fe ₃ O ₄ SiO ₂ -A was obtained; (5) Synthesis of carboxylated Fe ₃ O ₄ SiO ₂ (Fe ₃ O ₄ SiO ₂ -AB): 2g Fe ₃ O ₄ SiO ₂ -A and 4g anhydride Add to 45g N,N'-dimethylformamide, react the mixture at 50°C for 24h, magnetically separate the product, collect the sediment, remove the upper layer solution, wash with 50mL DMF and 50mL absolute ethanol for 2 to 3 times, then dry , to obtain Fe ₃ O ₄ SiO ₂ -AB; (6) Preparation of magnetic imprinting material: Add 0.25g cadmium acetate, 0.4g methacrylic acid, 0.3g salicylaldoxime to 50g methanol, stir overnight at room temperature, then add 0.5g Fe ₃ O ₄ SiO ₂ -AB, 1.5g EGDMA and 0.1g AIBN were reacted at 60°C for 24h under the protection of N ₂ After washing with 0 mL methanol for 2-3 times, the Cd ²⁺ was eluted with 10% sulfuric acid until no Cd ²⁺ was detected in the filtrate, and then the magnetic cadmium ion surface-imprinted polymer (Cd-M-IIP) was obtained. The characterization and analysis results of the obtained magnetic imprinted material are the same as those in Example 1.

Example 4

(1) Synthesis of Fe ₃ O ₄ : 5.56g FeSO ₄ ·7H ₂ O and 9.47g FeCl ₃ ·6H ₂ O were dissolved in 200g of ultrapure water, under the condition of passing through N ₂ , add 30g of FeSO 4 ·7H 2 O and 9.47g of FeCl 3 ·6H 2 O under the condition of vigorous stirring. ～28% ammonia water, react at 80°C for 2 hours, add 0.5g citric acid to react for 90 minutes, and magnetically separate after cooling, collect the black sediment, remove the supernatant, wash with ultrapure water until neutral, and then wash with 50mL of absolute ethanol for 2 ~3 times, vacuum drying to obtain Fe ₃ O ₄ nanoparticles; (2) Synthesis of Fe ₃ O ₄ SiO ₂ microspheres: 1g Fe ₃ O ₄ nanoparticles were ultrasonically dispersed in a mixed solution consisting of 50g isopropanol and 10g distilled water, Add 2g of ammonia water and 3g of tetraethyl orthosilicate, react at room temperature for 24 hours, magnetically separate the product, collect the sediment, remove the upper layer solution, wash with 50mL of distilled water and 50mL of absolute ethanol for 2 to 3 times, and then dry to obtain Fe ₃ O ₄ SiO ₂ microspheres; (3) Activation of Fe ₃ O ₄ SiO ₂ microspheres: add 10g of Fe ₃ O ₄ SiO ₂ microspheres to 200g of 10% phosphoric acid solution, react at 110°C for 5h, magnetically separate the product, and collect sediment, remove the upper layer solution, wash with distilled water until neutral, wash 2 to 3 times with 50mL absolute ethanol, and obtain activated Fe ₃ O ₄ SiO ₂ microspheres after drying; (4) Aminated Fe ₃ O ₄ SiO ₂ ( Fe ₃ O ₄ SiO ₂ -A) synthesis: 2g of activated Fe ₃ O ₄ SiO ₂ microspheres were added to 35g of toluene for ultrasonication, then 10g of anilinomethyltriethoxysilane was added, and NaOH with a mass concentration of 5% was added Adjust the pH of the solution to ≈11, nitrogen atmosphere, react at 80°C for 10 hours, magnetically separate the product, collect the sediment, remove the upper solution, wash with 50mL toluene and 50mL absolute ethanol for 2 to 3 times, and then dry to obtain Fe ₃ O ₄ SiO ₂ -A; (5) Synthesis of carboxylated Fe ₃ O ₄ SiO ₂ (Fe ₃ O ₄ SiO ₂ -AB): 1g Fe ₃ O ₄ SiO ₂ -A and 2g phthalic anhydride were added to 45gN,N In '-dimethylformamide, the mixture was reacted at 45°C for 24 hours, the product was separated magnetically, the sediment was collected, the upper solution was removed, washed 2-3 times with 50mL DMF and 50mL absolute ethanol, and then dried to obtain Fe ₃ O ₄ SiO ₂ -AB; (6) Preparation of magnetic imprinting material: Add 0.4g cadmium sulfate, 0.3g methacrylic acid, 0.3g salicylaldoxime to 50g methanol, stir overnight at room temperature, then add 1gFe ₃ O ₄ SiO ₂ - AB, 1.5g EGDMA and 0.11g AIBN were reacted at 60°C for 24h under the protection of N ₂ , the product was separated magnetically and washed with 50mL methanol After washing for 2 to 3 times, the Cd ²⁺ was eluted with 5% phosphoric acid until no Cd ²⁺ was detected in the filtrate, and the magnetic cadmium ion surface-imprinted polymer (Cd-M-IIP) was obtained. The characterization and analysis results of the obtained magnetic imprinted material are the same as those in Example 1.

Example 5

(1) Synthesis of Fe ₃ O ₄ : 2.78g FeSO ₄ ·7H ₂ O and 4.73g FeCl ₃ ·6H ₂ O were dissolved in 100g of ultrapure water, under the condition of passing through N ₂ , add 10g of FeSO 4 . ～28% ammonia water, react at 60°C for 1.5h, add 0.5g citric acid to react for 90min, magnetically separate after cooling, collect the black sediment, remove the supernatant, wash with ultrapure water until neutral, then wash with 50mL absolute ethanol 2 to 3 times, vacuum drying to obtain Fe ₃ O ₄ nanoparticles; (2) Synthesis of Fe ₃ O ₄ SiO ₂ microspheres: 1.5g Fe ₃ O ₄ nanoparticles were ultrasonically dispersed in a mixture composed of 85g absolute ethanol and 30g distilled water Add 3g of ammonia water and 9g of ethyl orthosilicate to the solution, react at room temperature for 10h, magnetically separate the product, collect the sediment, remove the upper solution, wash with 50mL of distilled water and 50mL of absolute ethanol for 2 to 3 times, and then dry to obtain Fe ₃ O ₄ SiO ₂ microspheres; (3) Activation of Fe ₃ O ₄ SiO ₂ microspheres: Add 10g of Fe ₃ O ₄ SiO ₂ microspheres to 100g of 10% hydrochloric acid solution, react at 110°C for 6h, and magnetically separate the product , collect the sediment, remove the upper solution, wash with distilled water until neutral, wash with 50mL absolute ethanol for 2 to 3 times, and dry to obtain activated Fe ₃ O ₄ SiO ₂ microspheres; (4) Aminated Fe ₃ O ₄ SiO ₂ (Fe ₃ O ₄ SiO ₂ -A) synthesis: 2g of activated Fe ₃ O ₄ SiO ₂ microspheres were added to 35g of toluene for ultrasonication, and then 10g of aminoethylaminopropyltrimethoxysilane was added at a mass concentration of 5 % NaOH solution, adjust pH ≈ 10, nitrogen atmosphere, react at 80°C for 5 hours, magnetically separate the product, collect the sediment, remove the upper solution, wash with 50mL toluene and 50mL absolute ethanol for 2 to 3 times, and then dry to obtain Fe ₃ O ₄ SiO ₂ -A; (5) Synthesis of carboxylated Fe ₃ O ₄ SiO ₂ (Fe ₃ O ₄ SiO ₂ -AB): 1g Fe ₃ O ₄ SiO ₂ -A and 2g trimellitic anhydride were added to 45gN,N' - In dimethylformamide, the mixture was reacted at 25°C for 10 h, the product was separated magnetically, the sediment was collected, the upper solution was removed, washed with 50mL DMF and 50mL absolute ethanol for 2 to 3 times, and then dried to obtain Fe ₃ O ₄ SiO ₂ -AB; (6) Preparation of magnetic imprinting material: Add 0.3g cadmium chloride, 0.25g methacrylic acid, 0.25g salicylaldoxime to 35g methanol, stir at room temperature overnight, then add 0.5gFe ₃ O ₄ SiO ₂ -AB, 2gEGDMA and 0.2gAIBN were reacted at 60°C for 24h under the protection of N ₂ , the products were separated magnetically and separated by 50m After washing with L methanol for 2 to 3 times, the Cd ²⁺ was eluted with 10% hydrochloric acid until no Cd ²⁺ was detected in the filtrate, and the magnetic cadmium ion surface-imprinted polymer (Cd-M-IIP) was obtained. The characterization and analysis results of the obtained magnetic imprinted material are the same as those in Example 1.

Claims (8)

1. a preparation method for magnetic cadmium ion surface imprinted polymer, is characterized by and comprise the steps:

(1) Fe ₃o ₄synthesis: FeSO ₄7H ₂o and FeCl ₃6H ₂o is dissolved in ultrapure water, logical N ₂under condition, add ammoniacal liquor under stirring, 60 ~ 80 DEG C of reaction 1 ~ 2h, adding citric acid reaction 60 ~ 90min, Magneto separate after cooling, collects black deposit, removes supernatant liquid, and washing is to neutral, and then vacuum-drying obtains Fe ₃o ₄nanoparticle; Wherein, in reaction, the mass ratio of each material is FeSO ₄7H ₂o:FeCl ₃6H ₂o: ammoniacal liquor: citric acid: ultrapure water=5:8 ~ 10:15 ~ 30:0.5 ~ 1:150 ~ 200;

(2) Fe ₃o ₄SiO ₂the synthesis of microballoon: Fe ₃o ₄nanoparticle ultrasonic disperse, in the mixing solutions of alcohol and distilled water, adds ammoniacal liquor and tetraethoxy, room temperature reaction 10 ~ 24h, product Magneto separate, collects settling, removes upper solution, and washing is also dry, obtains Fe ₃o ₄SiO ₂microballoon; Wherein, in reaction, the mass ratio of each material is Fe ₃o ₄nanoparticle: alcohol: distilled water: ammoniacal liquor: tetraethoxy=0.5 ~ 2.5:50 ~ 100:10 ~ 50:2 ~ 5:3 ~ 10;

(3) Fe ₃o ₄SiO ₂the activation of microballoon: Fe ₃o ₄SiO ₂microballoon joins in acidic solution, and 80 ~ 110 DEG C of reaction 5 ~ 10h, after product Magneto separate, collect settling, remove upper solution, and washing is also dry, obtains the Fe activated ₃o ₄SiO ₂microballoon; Wherein, in reaction, the mass ratio of each material is Fe ₃o ₄SiO ₂microballoon: acid solution=1:2 ~ 20;

(4) amination Fe ₃o ₄SiO ₂(Fe ₃o ₄SiO ₂-A) synthesis: the Fe of activation ₃o ₄SiO ₂microballoon joins in toluene ultrasonic, then adds amino silicane coupling agent, nitrogen atmosphere, and reaction 5 ~ 12h at 80 ~ 110 DEG C under adjustment pH to 10 ~ 11 conditions, product Magneto separate, collects settling, removes upper solution, and washing is also dry, obtains Fe ₃o ₄SiO ₂-A; Wherein, in reaction, the mass ratio of each material is activation Fe ₃o ₄SiO ₂microballoon: amino silicane coupling agent: toluene=2:10 ~ 15:30 ~ 50;

(5) carboxylated Fe ₃o ₄SiO ₂(Fe ₃o ₄SiO ₂-A-B) synthesis: Fe ₃o ₄SiO ₂-A and acid anhydrides join N, and in N'-dimethyl formamide, mixture reacts 10 ~ 24h at 25 ~ 50 DEG C, product Magneto separate, collect settling, remove upper solution, and washing is also dry, obtains Fe ₃o ₄SiO ₂-A-B; Wherein, in reaction, the mass ratio of each material is Fe ₃o ₄SiO ₂-A: acid anhydrides: N, N'-dimethyl formamide=1 ~ 2:2 ~ 5:40 ~ 50;

(6) preparation of magnetic blotting material: join in methyl alcohol by inorganic Ge Yan ﹑ Jia base Bing Xi Suan ﹑ salicylaldoxime, stirred overnight at room temperature, then adds Fe ₃o ₄SiO ₂-A-B, EGDMA and AIBN, N ₂in 60 DEG C of reaction 12 ~ 24h under protection, product Magneto separate with after methanol wash, then use acidic solution wash-out Cd ²⁺cd is can't detect to filtrate ²⁺after, obtain magnetic cadmium ion imprinted polymer (Cd-M-IIP); Wherein, in reaction, the mass ratio of each material is cadmium salt: Fe ₃o ₄SiO ₂-A-B: methacrylic acid: salicylaldoxime: EGDMA:AIBN: methyl alcohol=0.1 ~ 0.5:0.2 ~ 1:0.2 ~ 0.5:0.2 ~ 0.5:1 ~ 2:0.1 ~ 0.2:30 ~ 50.

2. the preparation method of magnetic cadmium ion surface imprinted polymer as claimed in claim 1, the alcohol that it is characterized by described step (2) is specially the one in Jia Chun ﹑ ethanol and Virahol.

3. the preparation method of magnetic cadmium ion surface imprinted polymer as claimed in claim 1, the acidic solution that it is characterized by described step (3) and (6) is specially H ₂sO ₄﹑ HNO ₃﹑ HCl and H ₃pO ₄one in solution, the mass concentration of acid solution is 5 ~ 20%.

4. the preparation method of magnetic cadmium ion surface imprinted polymer as claimed in claim 1, is characterized by described step (4) and regulates the reagent of pH to be specially one in the KOH of the NaOH ﹑ mass concentration 5% of the An Shui ﹑ mass concentration 5% of San Yi An ﹑ mass concentration 25 ~ 28%.

5. the preparation method of magnetic cadmium ion surface imprinted polymer as claimed in claim 1, the amino silicane coupling agent that it is characterized by described step (4) is specially the one in γ-aminopropyl three methoxy silane ﹑ γ-aminopropyl three ethoxy base silane ﹑ N-β (aminoethyl)-γ-aminopropyl three ethoxy base silane ﹑ phenylaminomethyl triethoxyl silane and aminoethylaminopropyl Trimethoxy silane.

6. the preparation method of magnetic cadmium ion surface imprinted polymer as claimed in claim 1, the described acid anhydrides that it is characterized by described step (5) is specially fourth two acid anhydrides ﹑ along the one in fourth enedioic acid acid anhydride ﹑ Tetra hydro Phthalic anhydride and trimellitic acid 1,2-anhydride.

7. the preparation method of magnetic cadmium ion surface imprinted polymer as claimed in claim 1, is characterized by inorganic cadmium salt in described step (6) and is specially Cd (NO ₃) ₂﹑ CdCl ₂and CdSO ₄middle one.

8. the preparation method of magnetic cadmium ion surface imprinted polymer as claimed in claim 1, the concentration that it is characterized by ammoniacal liquor in described step (1) and (2) is mass percentage concentration 25 ~ 28%.