阅读说明：本技术 一种除磷吸附剂及其制备方法和应用 (Phosphorus removal adsorbent and preparation method and application thereof ) 是由 刘自力 练钊华 左建良 刘奎良 林璟 王琪莹 于 2021-07-05 设计创作，主要内容包括：本发明提供了一种除磷吸附剂极其制备方法和应用。本发明的除磷吸附剂,在水体中结构稳定性好,具有多孔结构,在中性或酸性条件下,能有效吸附水体中的磷酸盐。此外,本发明的除磷吸附剂,具有强磁性,可以通过固液分离,方便的进行回收。本发明的除磷吸附剂,以镧为活性物质,对磷有特异性吸附作用,使得吸附剂对磷酸盐有很好的吸附效果。(The invention provides a phosphorus removal adsorbent, and a preparation method and application thereof. The dephosphorizing adsorbent disclosed by the invention has good structural stability in a water body, has a porous structure, and can effectively adsorb phosphate in the water body under a neutral or acidic condition. In addition, the phosphorus removal adsorbent has strong magnetism, and can be conveniently recovered through solid-liquid separation. The phosphorus removal adsorbent disclosed by the invention takes lanthanum as an active substance, has a specific adsorption effect on phosphorus, and has a good adsorption effect on phosphate.)

1. The phosphorus removal adsorbent is characterized by comprising an adsorbent matrix, wherein cobalt nanospheres and lanthanum elements are distributed on the surface of the adsorbent matrix, and the adsorbent matrix has a dodecahedron structure with a concave surface.

2. The phosphorus removal adsorbent of claim 1, wherein the particle size range of the phosphorus removal adsorbent is 200nm to 600 nm.

3. A method for preparing the phosphorus removal adsorbent of claim 1 or 2, comprising the steps of:

s1: preparing a mixed solution of transition metal salt and lanthanum salt;

s2: adding 2-methylimidazole into the mixed solution for reaction, and drying a product to obtain a lanthanum-doped metal organic framework material;

s3: and calcining the lanthanum-doped metal organic framework material under a protective atmosphere.

4. The method of claim 3, wherein the transition metal salt comprises a soluble cobalt salt.

5. The method as claimed in claim 3, wherein the lanthanum salt comprises at least one of lanthanum nitrate, lanthanum acetate, lanthanum chloride, and lanthanum sulfate.

6. The method of claim 3, wherein the mixed solution, solvent, comprises at least one of methanol, ethanol, and deionized water.

7. The method according to claim 3, wherein in step S1, the molar ratio of the transition metal salt to the lanthanum salt is (0.5-2): 1.

8. the method according to claim 3, wherein the temperature of the calcination in step S3 is 600-800 ℃.

9. The method of claim 3, wherein in step S3, the calcination time is 2-3 h.

10. Use of the phosphorus removal adsorbent according to any one of claims 1 to 3 in sewage treatment.

Technical Field

The invention belongs to the technical field of sewage treatment, and particularly relates to a phosphorus removal adsorbent and a preparation method and application thereof.

Background

Phosphorus is a key nutrient for plant, animal and bacterial growth, and most of phosphorus is present in water in the form of phosphate. The existence of excessive phosphorus can cause eutrophication of water bodies, so that algae are bred, the water quality is deteriorated, and finally, aquatic organisms such as fish and the like are killed, even the ecological system is broken down. Therefore, in order to limit eutrophication of water bodies, efficient phosphorus removal should be performed before the wastewater is discharged into waterways.

In recent years, many phosphate removal methods, such as chemical precipitation, microbiological treatment, and electrochemical methods, have been attempted to be developed at home and abroad. However, the high treatment cost and energy consumption of these processes have limited their effective use for phosphate removal in wastewater. In contrast, the adsorption method has attracted much attention because of its advantages such as simple operation, stable phosphorus removal performance, and no secondary pollution.

In the related art, Layered Double Hydroxides (LDH), biochar, and inorganic porous materials (such as porous SiO)₂) Phosphorus removal adsorbents such as Metal Organic Frameworks (MOFs) have been widely studied, but these adsorbents all have the problem of being difficult to recover.

Disclosure of Invention

The present invention is directed to solving at least one of the above problems in the prior art. Therefore, the phosphorus removal adsorbent provided by the invention has the advantages of good structural stability in water, good phosphorus removal effect and easiness in recovery.

The invention also provides a preparation method of the phosphorus removal adsorbent.

The invention also provides application of the phosphorus removal adsorbent in sewage treatment.

The invention provides a phosphorus removal adsorbent, which comprises an adsorbent matrix, wherein cobalt nanospheres and lanthanum elements are distributed on the surface of the adsorbent matrix, and the adsorbent matrix has a dodecahedron structure with a concave surface.

The phosphorus removal adsorbent disclosed by the invention at least has the following beneficial effects:

the phosphorus removal adsorbent has good structural stability in water, and can effectively adsorb phosphate in water under neutral or acidic conditions.

The phosphorus removal adsorbent disclosed by the invention takes Co as a magnetic core, and compared with an adsorbent taking Fe as a magnetic core, the phosphorus removal adsorbent has the advantages that the preparation method is simpler, and the Co is taken as the magnetic core, so that the material is not easy to lose magnetism due to oxidation.

The dephosphorizing adsorbent has strong magnetism, and can be conveniently recycled through solid-liquid separation.

The phosphorus removal adsorbent disclosed by the invention takes lanthanum as an active substance, has a specific adsorption effect on phosphorus, and has a good adsorption effect on phosphate.

After the phosphorus removal adsorbent is used, simple post-treatment is carried out through alkali, and the phosphorus removal adsorbent can be recycled after being dried, and is long in service life.

In the phosphorus removal adsorbent, the lanthanum element reserves are rich, and the preparation raw materials are easy to obtain.

According to some embodiments of the invention, the particle size of the phosphorus removal sorbent ranges from 200nm to 600 nm.

The second aspect of the present invention provides a method for preparing the above phosphorus removal adsorbent, comprising the steps of:

s1: preparing a mixed solution of transition metal salt and lanthanum salt;

s2: adding 2-methylimidazole into the mixed solution for reaction, and drying a product to obtain a lanthanum-doped metal organic framework material;

s3: and calcining the lanthanum-doped metal organic framework material under a protective atmosphere.

The preparation method of the phosphorus removal adsorbent has at least the following beneficial effects:

compared with the conventional Fe, the preparation method of the dephosphorizing adsorbent of the invention₃O₄、γ-Fe₂O₃、CoFeO₃And the preparation process of the magnetic adsorption material is greatly simplified, and the magnetic adsorption material is more beneficial to large-scale popularization and application.

According to the preparation method of the phosphorus removal adsorbent, lanthanum doping is in-situ doping, the lanthanum-doped metal organic framework material is calcined to obtain the derivative porous carbon, and the derivative porous carbon is used as the adsorbent, so that the structural stability of the material in a water body is improved.

In the preparation method of the phosphorus removal adsorbent, only one-time calcination is needed, and multiple sectional calcination is not needed.

According to some embodiments of the invention, the transition metal salt is a soluble cobalt salt.

According to some embodiments of the invention, the transition metal salt comprises a cobalt salt.

According to some embodiments of the invention, the cobalt salt comprises at least one of cobalt nitrate, cobalt acetate, cobalt chloride and cobalt sulphate.

According to some embodiments of the invention, the cobalt salt is cobalt nitrate.

According to some embodiments of the invention, the lanthanum salt is a soluble lanthanum salt.

According to some embodiments of the invention, the lanthanum salt comprises at least one of lanthanum nitrate, lanthanum acetate, lanthanum chloride, and lanthanum sulfate.

According to some embodiments of the invention, the lanthanum salt is lanthanum nitrate.

According to some embodiments of the invention, the mixed solution, solvent, comprises at least one of methanol, ethanol, and deionized water.

According to some embodiments of the invention, the solvent is methanol.

According to some embodiments of the present invention, in step S1, when preparing the mixed solution, the cobalt salt and the lanthanum salt are dissolved in the solvent to form a clear mixed solution.

According to some embodiments of the present invention, in step S1, the molar ratio of the cobalt salt to the lanthanum salt is (0.5-2): 1.

according to some embodiments of the present invention, in step S1, the molar ratio of the cobalt salt and the lanthanum salt is preferably 1: 1.

according to some embodiments of the present invention, in step S2, 2-methylimidazole is a specific coordinating organic that forms ZIF-67.

According to some embodiments of the present invention, in step S2, 2-methylimidazole is dissolved in methanol, ethanol or deionized water to form a 2-methylimidazole solution, and the 2-methylimidazole solution is added to the mixed solution of step S1 for reaction.

According to some embodiments of the present invention, in step S2, 2-methylimidazole is first dissolved in methanol, ethanol or deionized water to form a 2-methylimidazole solution, and 12mmol 2-methylimidazole can be dissolved in 10ml to 30ml of solvent.

According to some embodiments of the present invention, in step S2, 2-methylimidazole is added to the mixed solution to perform a reaction in a molar ratio of metal ions (lanthanum and cobalt) to 2-methylimidazole of 1: and 3, carrying out.

According to some embodiments of the invention, the temperature of the reaction in step S2 is room temperature.

According to some embodiments of the present invention, in step S2, after the reaction, the solid product is obtained by centrifugation and washing, and then the solid product is dried in vacuum.

According to some embodiments of the invention, the rotation speed of the centrifugation is 5000 to 10000rpm in step S2.

According to some embodiments of the invention, the centrifugation time is 3min to 10min in step S2.

According to some embodiments of the invention, in step S2, after centrifugation, the washing solution is methanol, ethanol or deionized water.

According to some embodiments of the invention, the number of washes after centrifugation in step S2 is 3 to 5.

According to some embodiments of the invention, the temperature of the vacuum drying is 60 ℃ to 80 ℃ in step S2.

According to some embodiments of the invention, the vacuum drying time in step S2 is 12h to 24 h.

According to some embodiments of the invention, the temperature of the calcination in step S3 is 600 ℃ to 800 ℃.

According to some embodiments of the invention, in step S3, the calcination time is 2h to 3 h.

According to some embodiments of the present invention, in step S3, the temperature increase rate during the calcination process is 5 ℃/min to 10 ℃/min.

According to some embodiments of the invention, the protective atmosphere for calcination in step S3 includes nitrogen, argon, and helium.

According to some embodiments of the invention, the atmosphere of the protective atmosphere for the calcination in step S3 is nitrogen.

The third aspect of the invention provides the application of the phosphorus removal adsorbent in sewage treatment.

When the phosphorus removal adsorbent is used for sewage treatment, the use method can be as follows:

when the phosphorus content in the neutral phosphorus-containing wastewater is less than or equal to 3mg/L, 0.4g/L of adsorbent is added, so that the phosphorus content is less than 0.5mg/L and the discharge standard of A-grade phosphate is reached.

After the phosphorus removal adsorbent is used for sewage treatment, the adsorbent can be quickly separated from water by an external magnetic field due to the strong magnetism of the adsorbent.

After separation, soaking the mixture for 24 hours in 0.1mol/LNaOH, performing magnetic separation after soaking, washing the mixture to be neutral by using deionized water, and drying the mixture for recycling.

Drawings

FIG. 1 is a graph comparing the adsorption performance of the adsorbents in examples 1 to 4 and comparative example 1 for phosphate.

FIG. 2 is a graph showing the infrared absorption spectra of the adsorbent of example 2 before and after adsorption.

FIG. 3 is a schematic diagram of the magnetic separation of the adsorbent of example 2.

Fig. 4 is a scanning electron micrograph of the phosphorus removal adsorbent prepared in example 2.

Fig. 5 is a scanning electron microscope image of the phosphorus removal adsorbent prepared in comparative example 1.

Detailed Description

The following are specific examples of the present invention, and the technical solutions of the present invention will be further described with reference to the examples, but the present invention is not limited to the examples.

Example 1

The phosphorus removal adsorbent prepared in this example specifically includes:

la: the molar ratio of Co is 1: 2, the preparation method of the lanthanum-doped ZIF-67 derived magnetic porous carbon dephosphorizing adsorbent comprises the following steps:

dissolving 2mmol of cobalt nitrate and 1mmol of lanthanum nitrate in 30ml of methanol to form a clear solution 1;

dissolving 12mmol of 2-methylimidazole in 10ml of methanol to form a clear solution 2;

quickly pouring the solution 2 into the solution 1, uniformly mixing, and magnetically stirring for 24 hours at room temperature;

washing three times by centrifugation with methanol as detergent at 8000rpm for 3min, taking the solid product and vacuum drying at 60 deg.C for 12h to obtain La: the molar ratio of Co is 1: 2, a lanthanum-doped metal-organic framework material;

calcining the lanthanum-doped metal organic framework material in a tubular furnace under the conditions as follows: n is a radical of₂The calcination temperature of 650 ℃ is reached at a temperature rise rate of 5 ℃/min under the atmosphere, and the calcination is carried out for 2h at 650 ℃.

After cooling to room temperature La was obtained: the molar ratio of Co is 1: 2 lanthanum doped phosphorus removal sorbent.

Sorbent activity testing:

adding 50ml KH with concentration of 100mg-P/L and pH of 7.0 + -0.1 into 100ml conical flask₂PO₄And (3) solution. With 0.02 gLa: the molar ratio of Co is 1: 2, adsorbing by using the lanthanum-doped phosphorus removal adsorbent.

The adsorption conditions were a temperature of 298K, constant temperature shaking at 200rpm for 24 h.

After the reaction, the ammonium molybdate spectrophotometry was used for analysis, and the result showed that the phosphate radical adsorption amount was 67.57 mg-P/g.

Example 2

The phosphorus removal adsorbent prepared in this example specifically includes:

dissolving 1.5mmol of cobalt nitrate and 1.5mmol of lanthanum nitrate in 30ml of methanol to form a clear solution 1;

dissolving 12mmol of 2-methylimidazole in 10ml of methanol to form a clear solution 2;

quickly pouring the solution 2 into the solution 1, and magnetically stirring for 24 hours at room temperature;

washing three times by centrifugation with methanol as detergent at 8000rpm for 3min, taking the solid product and vacuum drying at 60 deg.C for 12h to obtain La: the molar ratio of Co is 1: 1, a lanthanum-doped metal-organic framework material;

and (3) adding the La collected in the step 1: the molar ratio of Co is 1: 1, calcining the lanthanum-doped metal organic framework material in a tubular furnace under the conditions that: n is a radical of₂The calcination temperature of 650 ℃ is reached at a temperature rise rate of 5 ℃/min under the atmosphere, and the calcination is carried out for 2h at 650 ℃.

After cooling to room temperature La was obtained: the molar ratio of Co is 1: 1 of the phosphorus removal adsorbent.

Sorbent activity testing:

adding 50ml KH with concentration of 100mg-P/L and pH of 7.0 + -0.1 into 100ml conical flask₂PO₄And (3) solution. With 0.02 gLa: the molar ratio of Co is 1: adsorbing with the phosphorus removal adsorbent of 1.

The adsorption conditions were a temperature of 298K, constant temperature shaking at 200rpm for 24 h.

After the reaction, the ammonium molybdate spectrophotometry was used for analysis, and the result showed that the phosphate radical adsorption amount was 89.03 mg-P/g.

Example 3

The phosphorus removal adsorbent prepared in this example specifically includes:

dissolving 1mmol of cobalt nitrate and 2mmol of lanthanum nitrate in 30ml of methanol to form a clear solution 1;

dissolving 12mmol of 2-methylimidazole in 10ml of methanol to form a clear solution 2;

solution 2 was poured quickly into solution 1 and magnetically stirred at room temperature for 24 hours.

Finally, using methanol as a detergent, centrifugally washing three times at 8000rpm for 3min, taking a solid product, and vacuum-drying at 60 ℃ for 12h to obtain La: the molar ratio of Co is 2: 1, a lanthanum-doped metal-organic framework material;

and (3) adding the La collected in the step 1: the molar ratio of Co is 2: 1, calcining the lanthanum-doped metal organic framework material in a tubular furnace under the conditions that: n is a radical of₂The calcination temperature of 650 ℃ is reached at a temperature rise rate of 5 ℃/min under the atmosphere, and the calcination is carried out for 2h at 650 ℃. After cooling to room temperature La was obtained: the molar ratio of Co is 2: 1 of the phosphorus removal adsorbent.

Sorbent activity testing:

adding 50ml KH with concentration of 100mg-P/L and pH of 7.0 + -0.1 into 100ml conical flask₂PO₄And (3) solution. With 0.02 gLa: the molar ratio of Co is 2: 1 except that the adsorbent is used for adsorption.

The adsorption conditions were a temperature of 298K, constant temperature shaking at 200rpm for 24 h.

After the reaction, the ammonium molybdate spectrophotometry is used for analysis, and the result shows that the absorption amount of phosphate radical is 78.93 mg-P/g.

Example 4

The phosphorus removal adsorbent of this example was prepared in the same manner as in example 2.

Sorbent activity testing:

adding 50ml KH with concentration of 50mg-P/L and pH of 3.0 + -0.1 into 100ml conical flask₂PO₄And (3) solution. With 0.02 gLa: the molar ratio of Co is 1: adsorbing with the phosphorus removal adsorbent of 1.

The adsorption conditions were a temperature of 298K, constant temperature shaking at 200rpm for 24 h.

After the reaction, the ammonium molybdate spectrophotometry was used for analysis, and the result showed that the phosphate radical adsorption amount was 70.81 mg-P/g.

Comparative example 1

The phosphorus removal adsorbent is prepared by the comparative example, and specifically comprises the following components:

dissolving 3mmol of cobalt nitrate in 30ml of methanol to form a clear solution 1;

dissolving 12mmol of 2-methylimidazole in 10ml of methanol to form a clear solution 2;

solution 2 was poured quickly into solution 1 and magnetically stirred at room temperature for 24 hours. Finally, methanol is used as a detergent, centrifugal washing is carried out for three times under the conditions that the rotating speed is 8000rpm and the time is 3min, a solid product is taken and vacuum drying is carried out for 12h at the temperature of 60 ℃, and the metal organic framework material is obtained;

calcining the metal organic framework material collected in the step 1 in a tubular furnace under the conditions that: n is a radical of₂The calcination temperature of 650 ℃ is reached at a temperature rise rate of 5 ℃/min under the atmosphere, and the calcination is carried out for 2h at 650 ℃. Cooling to room temperature to obtain the dephosphorizing adsorbent.

Sorbent activity testing:

adding 50ml KH with concentration of 100mg-P/L and pH of 7.0 + -0.1 into 100ml conical flask₂PO₄And (3) solution. Adsorption was carried out with 0.02g of dephosphorizing adsorbent.

The adsorption conditions were a temperature of 298K, constant temperature shaking at 200rpm for 24 h.

After the reaction is finished, the ammonium molybdate spectrophotometry is used for analysis, and the result shows that the absorption amount of phosphate radical is 22.12 mg-P/g.

The comparative graphs of the adsorption performance of the adsorbents in examples 1 to 4 and comparative example 1 for phosphate are shown in fig. 1.

Examples 1-3 were prepared as different La: an adsorption example of the phosphorus removal adsorbent prepared by Co molar ratio under simulated neutral conditions; example 4 is an example of adsorption under simulated acidic conditions. It can be seen that the phosphorus removal adsorbent of the present invention has a good adsorption capacity no matter whether the phosphorus-containing simulated wastewater is acidic or neutral.

Comparative example 1 is an adsorbing material without doping lanthanum, and the adsorbing amount of phosphate is very low compared with examples 1-3, which shows that doping of lanthanum promotes the adsorbing performance of the material.

The infrared absorption spectrograms of the corresponding material before and after adsorption in example 2 are shown in fig. 2, and after the adsorption experiment, the infrared spectrum curve of the material shows a corresponding peak of a P-O bond, which proves that the material successfully adsorbs phosphate.

The magnetic separation diagram of the corresponding material in example 2 is shown in fig. 3, and it can be seen from fig. 3 that the phosphorus removal adsorbent prepared by the present invention has strong magnetism, and can be conveniently subjected to solid-liquid separation operation.

Fig. 4 is a scanning electron micrograph of the phosphorus removal adsorbent prepared in example 2, and fig. 5 is a scanning electron micrograph of the phosphorus removal adsorbent prepared in comparative example 1. As can be seen from fig. 4 and 5, the adsorbent matrix has a dodecahedral structure with a concave surface, and spherical nanoparticles are distributed on the surface, and the spherical nanoparticles are cobalt nanospheres.

The present invention has been described in detail with reference to the embodiments, but the present invention is not limited to the embodiments described above, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.