An amorphous cobalt basic carbonate, its preparation method and application

Abstract

The present invention belongs to the technical field of water treatment, and discloses an amorphous cobalt basic carbonate, a preparation method thereof and an application thereof. The preparation method comprises the following steps: S1. Mix cobalt nitrate hexahydrate and ethylene glycol to form a uniformly dispersed solution; S2. Control the temperature of the solution obtained in step S1 at 140-220 °C for solvent thermal reaction for 8-24 h; S3. Wash and dry the product obtained in step S2 to obtain amorphous cobalt basic carbonate. The application of amorphous cobalt basic carbonate as an adsorbent. The amorphous cobalt basic carbonate material prepared by the present invention has an ultra-high tetracycline adsorption capacity (up to 2746 mg / g), good cost-effectiveness, low biological toxicity and excellent recycling performance, and can efficiently remove tetracycline in water bodies.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and particularly relates to an amorphous basic cobalt carbonate, a preparation method thereof and an application thereof. Background Art

[0002] Tetracycline is a classic antibiotic, with a large annual consumption globally, used for preventing, controlling and treating various infectious diseases. In addition, it is also used as a food additive to improve the growth rate of animals. The extensive use of tetracycline has led to its wide spread in the environment, causing serious harm to humans and the ecosystem, and has attracted extensive attention due to problems such as its high toxicity and difficult degradation. The adsorption technology is a common method for removing tetracycline in industry. Compared with other common water treatment technologies (membrane treatment, biological treatment, coagulation, chemical oxidation, etc.), the adsorption technology is considered a highly competitive method due to its simple process, low energy consumption, mild operating conditions, few by-products and high efficiency.

[0003] In recent years, many materials have been used for adsorbing tetracycline in water, including biochar, clay minerals, nanomaterials, etc. However, the above-mentioned adsorption materials usually have problems such as high cost, complex synthesis process, low mechanical strength, easy agglomeration or low adsorption capacity. Summary of the Invention

[0004] In order to overcome the defects of adsorbents in the existing adsorption technology, the purpose of the present invention is to provide an amorphous basic cobalt carbonate, a preparation method thereof and an application thereof.

[0005] To achieve the above purpose, the technical solutions adopted by the present invention are as follows:

[0006] A preparation method of an amorphous basic cobalt carbonate, the steps are as follows:

[0007] S1. Mix cobalt nitrate hexahydrate and ethylene glycol to form a uniformly dispersed solution;

[0008] S2. Control the temperature of the solution obtained in step S1 at 140 - 220 °C for solvothermal reaction for 8 - 24 h;

[0009] S3. Wash and dry the product obtained in step S2 to obtain amorphous basic cobalt carbonate.

[0010] Preferably, in step S1, the raw material dosage ratio is cobalt nitrate hexahydrate∶ethylene glycol = (1 - 3) g∶10 mL.

[0011] Preferably, in step S1, after mixing cobalt nitrate hexahydrate and ethylene glycol, first stir at a rotation speed of 200 - 500 r / min for 10 - 30 min, and then ultrasonicate at an ultrasonic power of 100 - 300 W and an ultrasonic frequency of 20 - 40 KHz for 10 - 30 min to obtain a uniformly dispersed solution.

[0012] Preferably, in step S3, the product obtained in step S2 is washed several times with water first and then several times with ethanol.

[0013] Preferably, in step S3, the drying temperature is 40 - 80 °C and the time is 6 - 18 h.

[0014] An amorphous cobalt basic carbonate prepared by the above preparation method.

[0015] Application of amorphous cobalt basic carbonate as an adsorbent.

[0016] Preferably, it is used to adsorb organic pollutants in wastewater.

[0017] Preferably, the organic pollutant is tetracycline.

[0018] Preferably, the concentration of tetracycline in the wastewater is 50 - 150 mg / L, and the dosage ratio of amorphous cobalt basic carbonate to wastewater is amorphous cobalt basic carbonate∶wastewater = (0.5 - 2) mg∶50 mL.

[0019] Beneficial effects: The amorphous cobalt basic carbonate material prepared by the present invention has an ultra-high tetracycline adsorption capacity (up to 2746 mg / g), good cost-effectiveness, low biological toxicity and excellent recycling performance, and can efficiently remove tetracycline in water. Description of the Drawings

[0020] Figure 1 : X-ray diffraction patterns of amorphous cobalt basic carbonate and cobalt tetroxide prepared in Example 1 and Comparative Example 1.

[0021] Figure 2 : Infrared spectra of amorphous cobalt basic carbonate and cobalt tetroxide prepared in Example 1 and Comparative Example 1.

[0022] Figure 3 : Adsorption kinetic curves of amorphous cobalt basic carbonate and cobalt tetroxide prepared in Example 1 and Comparative Example 1.

[0023] Figure 4 : Recycling experimental data of amorphous cobalt basic carbonate prepared in Example 1. Detailed Description of the Invention

[0024] To make the present invention clearer and more definite, the following further details the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] Example 1

[0026] A preparation method of amorphous cobalt basic carbonate, comprising the following steps:

[0027] S1. Mix 2 g of cobalt(II) nitrate hexahydrate with 10 mL of ethylene glycol. First, continuously stir magnetically at a speed of 350 r / min for 20 min, and then sonicate in an ultrasonic device with a power of 300 W and a frequency of 40 KHz for 20 min to obtain a cobalt(II) nitrate hexahydrate / ethylene glycol solution;

[0028] S2. Place the solution obtained in step S1 into a stainless-steel autoclave lined with polytetrafluoroethylene that can accommodate it and seal the autoclave;

[0029] S3. Place the sealed autoclave containing the solution in step S2 into an electrothermal constant-temperature forced-air drying oven and keep it at a constant temperature of 180 °C for 16 h;

[0030] S4. Wash the product obtained in step S3 three times with ultrapure water and anhydrous ethanol respectively, and dry it in a vacuum drying oven at 60 °C for 12 h to obtain amorphous basic cobalt carbonate.

[0031] Example 2

[0032] A method for preparing amorphous basic cobalt carbonate, comprising the following steps:

[0033] S1. Mix 1 g of cobalt(II) nitrate hexahydrate with 10 mL of ethylene glycol. First, continuously stir magnetically at a speed of 200 r / min for 10 min, and then sonicate in an ultrasonic device with a power of 100 W and a frequency of 30 KHz for 10 min to obtain a cobalt(II) nitrate hexahydrate / ethylene glycol solution;

[0034] S2. Place the solution obtained in step S1 into a stainless-steel autoclave lined with polytetrafluoroethylene that can accommodate it and seal the autoclave;

[0035] S3. Place the sealed autoclave containing the solution in step S2 into an electrothermal constant-temperature forced-air drying oven and keep it at a constant temperature of 220 °C for 24 h;

[0036] S4. Wash the product obtained in step S3 three times with ultrapure water and anhydrous ethanol respectively, and dry it in a vacuum drying oven at 40 °C for 18 h to obtain amorphous basic cobalt carbonate.

[0037] Example 3

[0038] A method for preparing amorphous basic cobalt carbonate, comprising the following steps:

[0039] S1. Mix 3 g of cobalt(II) nitrate hexahydrate with 10 mL of ethylene glycol. First, continuously stir magnetically at a speed of 500 r / min for 30 min, and then sonicate in an ultrasonic device with a power of 200 W and a frequency of 20 KHz for 30 min to obtain a cobalt(II) nitrate hexahydrate / ethylene glycol solution;

[0040] S2. Place the solution obtained in step S1 into a stainless-steel autoclave lined with polytetrafluoroethylene that can accommodate it, and seal the autoclave.

[0041] S3. Place the sealed autoclave containing the solution obtained in step S2 into an electrothermal constant-temperature forced-air drying oven, and keep it at a constant temperature of 140 °C for 8 h.

[0042] S4. Wash the product obtained in step S3 three times successively with ultrapure water and anhydrous ethanol, and dry it in a vacuum drying oven at 80 °C for 6 h to obtain amorphous basic cobalt carbonate.

[0043] Comparative Example 1

[0044] Place the amorphous basic cobalt carbonate prepared in Example 1 into a tubular furnace, heat it to 500 °C at a heating rate of 5 °C / min and hold for 2 h, cool it to room temperature, and collect the calcined product to obtain cobalt tetroxide.

[0045] Product Structure Characterization

[0046] The X-ray diffraction patterns of the amorphous basic cobalt carbonate and cobalt tetroxide prepared in Example 1 and Comparative Example 1 are as Figure 1 shown. It can be seen that no characteristic diffraction peaks are observed for the amorphous basic cobalt carbonate, indicating that the amorphous basic cobalt carbonate prepared in the present invention is indeed an amorphous structure; the characteristic diffraction peaks of cobalt tetroxide obtained by calcining the amorphous basic cobalt carbonate at 19.2°, 31.2°, 36.8°, 44.9°, 59.5° and 65.1° correspond to the (111), (220), (311), (400), (511) and (440) crystal planes of cobalt tetroxide respectively, indicating that the calcined product of the amorphous basic cobalt carbonate prepared in the present invention is indeed cobalt tetroxide.

[0047] The infrared spectra of the amorphous basic cobalt carbonate and cobalt tetroxide prepared in Example 1 and Comparative Example 1 are as Figure 2 shown. It can be seen that the strong peak at 3501 cm -1 of the amorphous basic cobalt carbonate is caused by the stretching vibration of O-H, indicating the existence of a metal-OH bond; the interaction between carbonate ions (CO -1 3 2- -1 -1 2 3 2- -1 ​​​​​​, 1391 cm -1 , 1069 cm -1 , 834 cm -1 , 747 cm -1 and 686 cm -1 The peaks at are respectively attributed to ν(OCO 2 ) of the monodentate / polydentate carbonate ligand, ν(CO 3 ) / C-O, ν(C=O), δ(CO 3 ), δ(OCO) and ρ(OCO); the two characteristic peaks at 946 cm -1 and 512 cm -1 are attributed to the (Co-OH) bending mode and ρw(Co-OH); the absorption peaks of cobalt tetroxide at 660 cm -1 and 555 cm -1 are attributed to the characteristic infrared absorption peaks of cobalt tetroxide.

[0048] Application Example 1

[0049] 1 mg of amorphous basic cobalt carbonate and cobalt tetroxide prepared in Example 1 and Comparative Example 1 were respectively added to 50 mL of an aqueous tetracycline solution with a concentration of 100 mg / L, and stirred at 25 °C with a magnetic stirrer at a speed of 500 r / min for 900 min. Every once in a while, 2 mL of the suspension was taken out from the reactor with a syringe, filtered through a 0.22 μm membrane filter to remove adsorbed particles, and the filtered tetracycline solution was measured for tetracycline concentration at a wavelength of 280 nm with a UV spectrometer.

[0050] The adsorption kinetic curves of the amorphous basic cobalt carbonate and cobalt tetroxide prepared in Example 1 and Comparative Example 1 are as Figure 3 shown. It can be seen that the adsorption capacity of the amorphous basic cobalt carbonate is 2746 mg / g, and the adsorption capacity of cobalt tetroxide is 67 mg / g. It can be seen that the amorphous basic cobalt carbonate has excellent tetracycline adsorption capacity.

[0051] According to the same test method, it was found that the adsorption capacities of the amorphous basic cobalt carbonate prepared in Example 2 and Example 3 for tetracycline were 2631 mg / g and 2699 mg / g respectively, and they also had relatively large adsorption capacities and could be used for the adsorption and removal of tetracycline.

[0052] Cyclic performance test

[0053] Add 1 mg of the amorphous cobalt basic carbonate obtained in Example 1 to 50 mL of a tetracycline aqueous solution with a concentration of 100 mg / L, and stir it with a magnetic stirrer at a rotation speed of 500 r / min at 25 °C for 900 min until adsorption saturation is reached. Take out 2 mL of the suspension from the reactor with a syringe, filter it with a 0.22 μm membrane filter to remove the adsorbed particles, and measure the tetracycline concentration of the filtered tetracycline solution with a UV spectrometer at a wavelength of 280 nm; after adsorption, ultrasonically treat the adsorbed amorphous cobalt basic carbonate in ethanol of analytical reagent grade for 1 h, wash it with water three times, and then dry it at 60 °C. The adsorbent (amorphous cobalt basic carbonate) is regenerated; then adsorb tetracycline in the above manner in a cycle, and the cycle results are shown in Figure 4 , it can be seen that: after 5 cycles, its adsorption capacity is still 76.8% of the initial adsorption capacity, and it still maintains a relatively high adsorption capacity, indicating that the amorphous cobalt basic carbonate prepared by the present invention can be recycled and has good stability.

Claims

1. A preparation method of amorphous cobalt basic carbonate, characterized in that, the steps are as follows: S1. Mix cobalt nitrate hexahydrate and ethylene glycol, first stir at a rotation speed of 200 - 500 r / min for 10 - 30 min, and then ultrasonicate for 10 - 30 min under the conditions of an ultrasonic power of 100 - 300 W and an ultrasonic frequency of 20 - 40 KHz to obtain a uniformly dispersed solution; S2. Control the temperature of the solution obtained in step S1 at 140 - 220 °C for solvothermal reaction for 8 - 24 h; S3. Wash and dry the product obtained in step S2 to obtain amorphous cobalt basic carbonate.

2. The preparation method of amorphous cobalt basic carbonate according to claim 1, characterized in that: In step S1, the raw material dosage ratio is cobalt nitrate hexahydrate ∶ ethylene glycol = (1 - 3) g ∶ 10 mL.

3. The preparation method of amorphous cobalt basic carbonate according to claim 1, characterized in that: In step S3, the product obtained in step S2 is first washed several times with water and then several times with ethanol.

4. The preparation method of amorphous cobalt basic carbonate according to claim 1, characterized in that: In step S3, the drying temperature is 40 - 80 °C and the time is 6 - 18 h.

5. An amorphous cobalt basic carbonate prepared by using the preparation method of amorphous cobalt basic carbonate according to any one of claims 1 - 4.

6. An application of the amorphous cobalt basic carbonate according to claim 5 as an adsorbent.

7. The application of the amorphous cobalt basic carbonate according to claim 6, characterized in that: It is used for adsorbing organic pollutants in wastewater.

8. The application of the amorphous cobalt basic carbonate according to claim 7, characterized in that: The organic pollutant is tetracycline.

9. The application of the amorphous cobalt basic carbonate according to claim 8, characterized in that: The concentration of tetracycline in the wastewater is 50 - 150 mg / L, and the dosage ratio of amorphous cobalt basic carbonate to wastewater is amorphous cobalt basic carbonate ∶ wastewater = (0.5 - 2) mg ∶ 50 mL.

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