Method for synthesizing magnetic al2o3 nanomaterials by urease

Abstract

The application provides a method for synthesizing magnetic Al2O3 nanomaterials by urease, and relates to the technical field of magnetic nanomaterials. The method comprises the following steps: firstly, dispersing salt and urea in water, dispersing ferroferric oxide and a surfactant in water, then mixing the two, adding urease, controlling the stirring speed, performing enzymatic hydrolysis reaction, and obtaining a precipitate; finally, washing and drying the precipitate, and performing calcination treatment to obtain the magnetic Al2O3 nanomaterials. The magnetic Al2O3 nanomaterials have high specific surface area and magnetism, and can significantly remove organic matters in water.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of magnetic nanomaterials, and particularly relates to a method for synthesizing magnetic Al2O3 nanomaterials by urease method. BACKGROUND

[0002] Currently, adsorbents commonly used for removing antibiotic pollutants include activated carbon, biochar, mineral materials, metal oxides and hydroxides, metal organic frameworks and composite materials. The activated carbon adsorbent has high cost and poor regeneration performance, and the metal organic framework has poor stability.

[0003] Compared with other materials, alumina is one of the main metal oxides in minerals and soils, can be synthesized in a simple method in the laboratory, has good stability, and can be applied to the adsorption field by regulating the specific surface area, pore structure and surface charge through changing the synthesis parameters. For example, the di-aluminum trioxide nanomaterial is modified based on the urease hydrolysis method, the material structure and adsorption performance are optimized, the adsorption efficiency and stability are significantly improved, and the antibiotics are quickly and efficiently removed. However, there is little research on the magnetic Al2O3 nanomaterials. SUMMARY

[0004] Based on the above problems, the present application provides a method for synthesizing magnetic Al2O3 nanomaterials by urease method. In the process of synthesizing di-aluminum trioxide nanomaterials by urease hydrolysis method, ferric oxide and a surfactant are first added, then urease is added, and process parameters such as stirring speed are controlled to obtain a magnetic Al2O3 nanomaterial with excellent adsorption performance.

[0005] The method for synthesizing magnetic Al2O3 nanomaterials by urease method provided by the present application comprises the following steps:

[0006] (1) aluminum salt and urea are mixed and ultrasonically dispersed in water at a mass ratio of 1:3-6, then ammonia water is added to adjust the pH value of the solution to neutral or weak alkaline to obtain solution I;

[0007] (2) ferric oxide and a surfactant are mixed and dispersed in water at a mass ratio of 1-3:1-3 to obtain solution II;

[0008] (3) the solution I and the solution II are mixed, the mass ratio of aluminum salt to ferric oxide is controlled to be 2-3:1, urease is added after fully mixing, and stirring is uniform, wherein the stirring speed is 300-500 r / min; after stopping stirring, the reaction is carried out at 35-45℃ for 20-30h, and the precipitate is collected by centrifugation after the reaction is completed;

[0009] (4) the precipitate is washed and dried to obtain a precursor;

[0010] (5) The precursor is calcined at a temperature of 450℃~550℃ for 1h~3h to obtain magnetic Al2O3 nanomaterials.

[0011] Preferably, the aluminum salt in step (1) is any one of aluminum chloride, aluminum sulfate, and aluminum nitrate.

[0012] Preferably, the surfactant is a quaternary ammonium salt surfactant.

[0013] Preferably, the amount of urease added in step (3) accounts for 3 to 5% of the mass of the aluminum chloride.

[0014] Preferably, step (4) involves washing with deionized water and ethanol.

[0015] Preferably, the drying temperature in step (4) is 50°C to 70°C.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] This invention provides a method for preparing magnetic aluminum oxide nanomaterials. The method involves first dispersing salt and urea in water, then dispersing ferric oxide and a surfactant in water, followed by mixing the two mixtures and adding urease. The urease reaction is carried out under controlled stirring speed to obtain a precipitate. Finally, the precipitate is washed, dried, and calcined to obtain magnetic Al₂O₃ nanomaterials. The magnetic Al₂O₃ nanomaterials of this invention possess high specific surface area and magnetic properties, and can significantly remove organic matter from water. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the preferred embodiments of this invention will be described in further detail below with reference to the examples. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. The quaternary ammonium salt surfactant used in this invention is octadecyltrimethylammonium chloride.

[0019] Example 1

[0020] A method for synthesizing magnetic Al2O3 nanomaterials using urease includes the following steps:

[0021] (1) Aluminum chloride and urea are mixed in a mass ratio of 1:3 and ultrasonically dispersed in water. Then, ammonia is added dropwise to adjust the pH of the solution to 8, thus obtaining solution I.

[0022] (2) Mix ferric oxide and quaternary ammonium salt surfactant at a mass ratio of 1:2, disperse in water, and obtain solution II;

[0023] (3) the solution I and the solution II are mixed, the mass ratio of aluminum salt and ferroferric oxide is controlled to be 2:1, urease is added after being mixed uniformly, and the stirring is uniform, wherein the stirring speed is 500 r / min; after the stirring is stopped, the reaction is carried out at 37℃ for 24 h, and the precipitate is collected after centrifugation; wherein the added amount of urease accounts for 3% of the mass of the aluminum chloride.

[0024] (4) the precipitate is washed by using deionized water and ethanol, and then dried at a temperature of 60℃ overnight to obtain a precursor;

[0025] (5) the precursor is calcined at a temperature of 500℃ for 2 h to obtain the magnetic Al2O3 nanomaterial.

[0026] It is detected that the specific surface area of the magnetic Al2O3 nanomaterial prepared in embodiment 1 is 1224.1 m 2 / g, and the pore volume is 0.50 cm 3 / g.

[0027] Embodiment 2

[0028] A method for synthesizing a magnetic Al2O3 nanomaterial by using urease includes the following steps:

[0029] (1) aluminum sulfate and urea are mixed according to a mass ratio of 1:3, and then ultrasonic dispersion is carried out in water, and then ammonia water is added dropwise to adjust the pH value of the solution to be neutral or weakly alkaline to obtain a solution I;

[0030] (2) ferroferric oxide and quaternary ammonium salt surfactant are mixed according to a mass ratio of 2:3, and then dispersed in water to obtain a solution II;

[0031] (3) the solution I and the solution II are mixed, the mass ratio of aluminum salt and ferroferric oxide is controlled to be 3:1, urease is added after being mixed uniformly, and the stirring is uniform, wherein the stirring speed is 500 r / min; after the stirring is stopped, the reaction is carried out at 37℃ for 24 h, and the precipitate is collected after centrifugation; wherein the added amount of urease accounts for 3% of the mass of the aluminum sulfate;

[0032] (4) the precipitate is washed by using deionized water and ethanol, and then dried at a temperature of 60℃ overnight to obtain a precursor;

[0033] (5) the precursor is calcined at a temperature of 500℃ for 2 h to obtain the magnetic Al2O3 nanomaterial.

[0034] It is detected that the specific surface area of the magnetic Al2O3 nanomaterial prepared in embodiment 2 is 1189.5 m 2 / g, and the pore volume is 0.53 cm 3 / g.

[0035] Embodiment 3

[0036] A method for synthesizing magnetic Al2O3 nanomaterials by urease method comprises the following steps:

[0037] (1) Aluminum nitrate and urea are mixed in a mass ratio of 1:5 and ultrasonically dispersed in water, then ammonia water is added dropwise to adjust the pH value of the solution to neutral or weak alkaline to obtain solution I;

[0038] (2) Ferroferric oxide and quaternary ammonium salt surfactant are mixed in a mass ratio of 3:1 and dispersed in water to obtain solution II;

[0039] (3) The solution I and the solution II are mixed, the mass ratio of aluminum salt to ferroferric oxide is controlled to be 2:1, urease is added after fully mixing uniformly, and stirring is uniformly carried out at a stirring speed of 300 r / min; after stopping stirring, reaction is carried out at 37℃ for 24 h, and the precipitate is collected by centrifugation after the reaction is completed; wherein the addition amount of urease accounts for 5% of the mass of the aluminum nitrate;

[0040] (4) The precipitate is washed with deionized water and ethanol, and then dried at a temperature of 70℃ overnight to obtain a precursor;

[0041] (5) The precursor is calcined at a temperature of 550℃ for 1 h to obtain the magnetic Al2O3 nanomaterials.

[0042] It is detected that the specific surface area of the magnetic Al2O3 nanomaterials prepared in Example 3 is 1301.4 m 2 / g, and the pore volume is 0.52 cm 3 / g.

[0043] Example 4

[0044] A method for synthesizing magnetic Al2O3 nanomaterials by urease method comprises the following steps:

[0045] (1) Aluminum nitrate and urea are mixed in a mass ratio of 1:5 and ultrasonically dispersed in water, then ammonia water is added dropwise to adjust the pH value of the solution to neutral or weak alkaline to obtain solution I;

[0046] (2) Ferroferric oxide and quaternary ammonium salt surfactant are mixed in a mass ratio of 3:1 and dispersed in water to obtain solution II;

[0047] (3) The solution I and the solution II are mixed, the mass ratio of aluminum salt to ferroferric oxide is controlled to be 2:1, urease is added after fully mixing uniformly, and stirring is uniformly carried out at a stirring speed of 300 r / min; after stopping stirring, reaction is carried out at 37℃ for 24 h, and the precipitate is collected by centrifugation after the reaction is completed; wherein the addition amount of urease accounts for 5% of the mass of the aluminum nitrate;

[0048] (4) the precipitate is washed with deionized water and ethanol, and dried at 50°C overnight to obtain a precursor;

[0049] (5) the precursor is calcined at 450°C for 3h to obtain the magnetic Al2O3 nanomaterial.

[0050] It is detected that the specific surface area of the magnetic Al2O3 nanomaterial prepared in Example 4 is 1142.6m 2 / g, and the pore volume is 0.51cm 3 / g.

[0051] Comparative Example 1

[0052] A method for synthesizing Al2O3 nanomaterial by urease method comprises the following steps:

[0053] (1) aluminum chloride and urea are mixed in water at a mass ratio of 1:3, and then ammonia water is added dropwise to adjust the pH value of the solution to 8 to obtain solution I;

[0054] (2) the solution I is added with urease at 37°C, stirred uniformly, then stirring is stopped and reacted for 24h, and after the reaction is completed, the precipitate is collected by centrifugation; wherein the addition amount of urease accounts for 3% of the mass of the aluminum chloride, and the stirring speed is 500r / min;

[0055] (3) the precipitate is washed with deionized water and ethanol, and dried at 60°C overnight to obtain a precursor;

[0056] (4) the precursor is calcined at 500°C for 2h to obtain the Al2O3 nanomaterial.

[0057] It is detected that the specific surface area of the Al2O3 nanomaterial prepared in Comparative Example 1 is 811.3m 2 / g, and the pore volume is 0.25cm 3 / g.

[0058] Comparative Example 2

[0059] A method for synthesizing magnetic Al2O3 nanomaterial by urease method comprises the following steps:

[0060] (1) aluminum chloride and urea are mixed in water at a mass ratio of 1:3, and then ammonia water is added dropwise to adjust the pH value of the solution to 8 to obtain solution I;

[0061] (2) the solution II is obtained by dispersing ferric oxide in water;

[0062] (3) mixing the solution I and the solution II, controlling the mass ratio of aluminum salt and ferric oxide to be 2:1, after mixing uniformly, adding urease, after stirring uniformly, stopping stirring, reacting at 37℃ for 24h, wherein the added amount of urease accounts for 3% of the mass of the aluminum chloride. After reaction, collecting the precipitate by centrifugation; wherein the stirring speed is 500r / min;

[0063] (4) after washing the precipitate with deionized water and ethanol, drying at 60℃ overnight to obtain a precursor;

[0064] (5) calcining the precursor at 500℃ for 2h to obtain the magnetic Al2O3 nanomaterial.

[0065] It is detected that the specific surface area of the magnetic Al2O3 nanomaterial prepared in the comparative example 2 is 1007.4m 2 / g, and the pore volume is 0.32cm 3 / g.

[0066] The nanomaterials prepared in examples 1-4 and comparative examples 1-2 are used as adsorbents to carry out adsorption experiments on tetracycline in water, and the specific operation is as follows:

[0067] First, prepare a tetracycline aqueous solution with a concentration of 25ug / mL; then take 30mL of the tetracycline aqueous solution, add 7.5mg of adsorbent, and carry out adsorption experiments respectively, after adsorption equilibrium, measure the removal rate of tetracycline in water, as shown in Table 1.

[0068] Table 1

[0069] Adsorbent Tetracycline removal rate Example 1 93.4％ Example 2 92.1％ Example 3 96.0％ Example 4 92.8％ Comparative Example 1 62.5％ Comparative Example 2 78.3％

[0070] The above-described examples are part of the embodiments of the present application, rather than all the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

Claims

1. A method for urease synthesis of magnetic Al203 nanomaterials, characterized by, The method comprises the following steps: (1) mixing aluminum salt and urea in water with a mass ratio of 1:3-6 by ultrasonic dispersion, then adding ammonia water to adjust the pH value of the solution to neutral or weak alkaline to obtain solution I; (2) mixing ferroferric oxide and quaternary ammonium salt surfactant in water with a mass ratio of 1-3:1-3 to obtain solution II; (3) mixing the solution I and the solution II, controlling the mass ratio of aluminum salt and ferroferric oxide to be 2-3:1, adding urease after fully mixing and uniformly stirring at a stirring speed of 300-500 r / min, then stopping stirring and reacting at 35-45 DEG C for 20-30 h, centrifuging and collecting the precipitate after the reaction is completed; (4) washing and drying the precipitate to obtain a precursor; (5) calcining the precursor at a temperature of 450 DEG C-550 DEG C for 1 h-3 h to obtain Al2O3 nano material with magnetism; The aluminum salt in step (1) is any one of aluminum chloride, aluminum sulfate and aluminum nitrate. The urease is added in step (3) in an amount of 3-5% of the mass of the aluminum salt.

2. The method for urease synthesis of magnetic Al203 nanomaterials according to claim 1, characterized by that, Step (4) is washing with deionized water and ethanol.

3. The method for urease synthesis of magnetic Al203 nanomaterials according to claim 1, characterized by that, The drying temperature in step (4) is 50 DEG C-70 DEG C.