阅读说明：本技术 一种磁性纳米复合材料及其制备方法 (Magnetic nano composite material and preparation method thereof ) 是由 陶虎春 邓丽平 于 2020-05-18 设计创作，主要内容包括：本发明公开了一种磁性纳米复合材料及其制备方法,包括采用热聚合法制备g-C3N4；采用溶剂热法制备磁性CoFe2O4；将g-C3N4和磁性CoFe2O4混合,采用超声水热法制备CoFe2O4/g-C3N4磁性纳米复合材料。本发明制备的CoFe2O4/g-C3N4磁性纳米复合材料,CoFe2O4均匀附着在片状g-C3N4的表面,并未进入其晶格内；磁性纳米复合材料具有较好的稳定性,对CIP有较好的光催化降解作用,经多次循环回收利用后,降解率仍能达到最初效率的90％以上,同时,借助磁性纳米复合材料的磁性,能将其从废水中快速分离,是一种可循环利用的环境友好型的光催化材料。(The invention discloses a magnetic nano composite material and a preparation method thereof, which comprises the steps of preparing g-C3N4 by adopting a thermal polymerization method; preparing magnetic CoFe2O4 by adopting a solvothermal method; and mixing g-C3N4 and magnetic CoFe2O4, and preparing the CoFe2O4/g-C3N4 magnetic nanocomposite by an ultrasonic hydrothermal method. According to the CoFe2O4/g-C3N4 magnetic nano composite material prepared by the invention, CoFe2O4 is uniformly attached to the surface of the flaky g-C3N4 and does not enter the crystal lattice of the flaky g-C3N 4; the magnetic nano composite material has better stability and better photocatalytic degradation effect on CIP, the degradation rate can still reach more than 90% of the initial efficiency after repeated recycling, and meanwhile, the magnetic nano composite material can be quickly separated from wastewater by virtue of the magnetism of the magnetic nano composite material, so that the magnetic nano composite material is a recyclable environment-friendly photocatalytic material.)

1. A preparation method of a magnetic nano composite material is characterized by comprising the following steps:

preparing g-C3N4 by adopting a thermal polymerization method;

preparing magnetic CoFe2O4 by adopting a solvothermal method;

mixing the g-C3N4 and the magnetic CoFe2O4, and preparing a CoFe2O4/g-C3N4 magnetic nanocomposite material by an ultrasonic hydrothermal method; the method specifically comprises the following steps:

weighing a first mass of the g-C3N4 and a second mass of the magnetic CoFe2O4, and adding into a ceramic crucible;

adding ethanol with a first volume and ultrapure water with a second volume into the ceramic crucible, and carrying out ultrasonic treatment for a sixth time;

continuously stirring and heating in a water bath with a second water bath temperature, and evaporating to obtain a first mixture;

placing the ceramic crucible containing the first mixture in a muffle furnace, heating to a sixth temperature at a third heating speed, burning for a seventh time at the sixth temperature, and cooling to room temperature to obtain a second mixture;

and washing the second mixture with ultrapure water for multiple times, and placing the second mixture in an oven to be dried at a seventh temperature for an eighth time to obtain the CoFe2O4/g-C3N4 magnetic nanocomposite.

2. The method for preparing the magnetic nanocomposite material as claimed in claim 1, wherein the g-C3N4 is prepared by a thermal polymerization method, and the method specifically comprises the following steps:

adding melamine into a ceramic crucible, putting the ceramic crucible into the muffle furnace for primary burning, setting the temperature of the primary burning to be raised to a first temperature at a first temperature raising speed, and burning for a first time;

cooling to obtain a sintered solid, and grinding the sintered solid for a first grinding time to obtain a first solid powder;

adding the first solid powder into a ceramic crucible, putting the ceramic crucible into a muffle furnace for secondary burning, setting the temperature of the secondary burning to be raised to a second temperature at a second temperature raising speed, and burning for a second time;

cooling to obtain a second solid powder, and milling said second solid powder for a second milling time to obtain said g-C3N 4.

3. The method for preparing the magnetic nanocomposite material according to claim 2, wherein the method for preparing the magnetic CoFe2O4 by adopting the solvothermal method specifically comprises the following steps:

dissolving Co (NO3) 2.6H 2O and Fe (NO3) 3.9H 2O in a first molar ratio in ultrapure water to obtain a solution A;

dissolving a first mass of C6H8O7 · H2O in ultrapure water so that the molar ratio of metal ions (Co2+ + Fe3 +)/citric acid is equal to 1.0, obtaining a solution B;

dropwise adding the solution A into the solution B under magnetic stirring to obtain a first mixed solution;

heating the first mixed solution in a water bath at the first water bath temperature for a third time to react to obtain a second mixed solution;

putting the second mixed solution into an oven, and drying at a fourth temperature for a fourth time to obtain gel;

and (3) burning the gel at a fifth temperature for a fifth time to obtain the magnetic CoFe2O 4.

4. The method of preparing a magnetic nanocomposite material according to claim 3,

the first temperature rise speed is 1-3 ℃/min, the first temperature is 500-600 ℃, and the first time is 3.5-4.5 h;

the second temperature rise speed is 1-3 ℃/min, the second temperature is 450-550 ℃, and the second time is 1.5-2.5 h;

the first grinding time is 15-20min, and the second grinding time is 15-20 min;

the first molar ratio is 1:1.8-1: 2.2;

the first water bath temperature is 55-65 ℃, the third time is 0.8-1.3h, the fourth temperature is 85-95 ℃, and the fourth time is 22-26 h;

the fifth temperature is 280-520 ℃, and the fifth time is 3.5-4.5 h.

5. The method of preparing a magnetic nanocomposite material according to claim 4,

the ratio of the second mass to the first mass is 0.08: 1-0.45;

the sixth time is 25-35 min;

the temperature of the second water bath is 75-85 ℃;

the third temperature rise speed is 1.5-2.5 ℃/min, the sixth temperature is 250-350 ℃, and the seventh time is 1.5-2.5 h;

the seventh temperature is 55-65 ℃, and the eighth time is 22-26 h.

6. The method of preparing a magnetic nanocomposite material according to claim 5,

the first temperature rise speed is 2 ℃/min, the first temperature is 550 ℃, and the first time is 4 h;

the second heating speed is 2 ℃/min, the second temperature is 500 ℃, and the second time is 2 h;

the first grinding time is 20min, and the second grinding time is 20 min;

the first molar ratio is 1: 2;

the first water bath temperature is 60 ℃, the third time is 1h, the fourth temperature is 90 ℃, and the fourth time is 24 h;

the fifth temperature is 300 ℃, 400 ℃ or 500 ℃, and the fifth time is 4 hours.

7. The method of preparing a magnetic nanocomposite material according to claim 6,

the ratio of the second mass to the first mass is 0.1:1, 0.2:1 or 0.4: 1;

the sixth time is 30 min; the temperature of the second water bath is 80 ℃;

the third heating speed is 2 ℃/min, the sixth temperature is 300 ℃, and the seventh time is 2 h;

the seventh temperature is 60 ℃, and the eighth time is 24 hours.

8. The method of claim 7, wherein the CoFe2O4/g-C3N4 magnetic nanocomposite comprises the following components in percentage by weight: the mass part ratio of CoFe2O4/g-C3N4 is 0.4:1, and the fifth temperature is 300 ℃.

9. A magnetic nanocomposite, characterized in that the magnetic nanocomposite is CoFe2O4/g-C3N4, which is prepared by the method of preparing a magnetic nanocomposite according to any one of claims 1 to 8.

10. The magnetic nanocomposite of claim 9, wherein the CoFe2O4/g-C3N4 magnetic nanocomposite comprises the following components in parts by weight: the mass part ratio of CoFe2O4/g-C3N4 is 0.4: 1.

Technical Field

The invention relates to the technical field of new materials, in particular to a magnetic nano composite material and a preparation method thereof.

Background

With the development of economy and the improvement of the living standard of human beings, the use amount and the discharge amount of antibiotics are also increased year by year. According to statistics, the usage amount of antibiotics is about 10-20 ten thousand tons every year around the world, and 50 percent of the antibiotics are used for treating animal diseases and promoting growth. The consumption of global human antibiotics increased by 36% in the first 10 years of the 21 st century. Research shows that the antibiotic concentration in the global fresh water exceeds the standard: the concentration of antibiotics detected in the fresh water of America is as high as 15 mug/L, more than 10 mug/L in Europe, more than 50 mug/L in Africa, and the most serious pollution condition in Asia-Pacific region is more than 450 mug/L. Among them, the problem of antibiotics in China is not a little remarkable. The data show that 68 antibiotics are detected in the surface water of China and 39 antibiotics are detected in lakes, wherein quinolones are the antibiotics with the highest detection frequency and risk. Antibiotics in the environment may cause harm to microorganisms and aquatic organisms, affect the community structure and ecological environment of the organisms, and further affect higher organisms through a food chain and a food net. Long-term drinking of water containing antibiotics can affect the kidney function of human body, interfere normal hormone level, reduce the immunity of organism, etc. Therefore, a stable, efficient and environment-friendly means for solving the ecological environment problem caused by antibiotics is urgently needed to be found.

In recent years, advanced oxidation techniques have been extensively studied. The semiconductor photocatalysis technology is favored by a plurality of researchers due to the excellent characteristics of being capable of being carried out at normal temperature, utilizing sunlight, having wide catalyst source, being capable of thoroughly removing pollutants and the like. At present, semiconductor photocatalysts widely researched comprise TiO2, ZnO, CdS, g-C3N4 and the like, and are mainly used for fuel cells, photocatalytic degradation, gas storage, carbon dioxide reduction, hydrogen production by photolysis of water and the like. Among them, graphite carbon nitride (g-C3N 4) is a semiconductor material that is non-toxic, low in manufacturing cost, free of metal elements, and rich in the surface content of required elements, and has been gaining the popularity of many researchers.

Carbon nitride (C3N4) has 5 structures (β -C3N4, α -C3N4, g-C3N4, p-C3N4, and C-C3N4), with g-C3N4 being the most stable at ambient temperature and pressure. It is widely believed that g-C3N4 is a graphite-like layered material, and the layers are connected by weak van der Waals force, and the tri-s-triazine group is used as a basic unit. The photogenerated electron-hole pair of g-C3N4 has strong redox ability. However, when the g-C3N4 is applied to water for degrading pollutants, the g-C3N4 has the defects of easy recombination of photo-generated electron-hole pairs, small specific surface area, low conductivity, unfavorable recovery and the like. For this reason, many studies have conducted modification and doping of g — C3N4, such as doping with metallic elements Cu, Fe, Co, and the like, nonmetallic elements C, P, S, and the like, and composite oxides such as TiO2, Fe3O4, and the like. By doping these elements or oxides, the band gap energy of g-C3N4 can be reduced, and the absorption intensity in the visible light range can be greatly improved.

At present, a CoFe2O4/g-C3N4 magnetic nano composite material and a preparation method thereof (ZL201710004846.6) disclose that g-C is prepared completely₃N₄Then, it is reacted with FeCl₃·6H₂O and CoCl₂·4H₂One-step synthesis of CoFe by mixing with O₂O₄/g-C₃N₄The burning temperature during this step was 180 ℃. As can be seen from the description of FIG. 3 (FIG. 1), there are only distinct pores and lamellar structures, but no intact cubic structures, and therefore CoFe₂O₄The cubic spinel structure may not be completely formed, and the CoFe2O4 has large grain diameter, small specific surface area and low catalytic efficiency.

Disclosure of Invention

The invention aims to solve the technical problems of large particle size, small specific surface area and low catalytic efficiency of the existing magnetic nano composite material, and provides a magnetic nano composite material and a preparation method thereof.

According to an aspect of the present invention, there is provided a method for preparing a magnetic nanocomposite, comprising the steps of:

preparing g-C3N4 by adopting a thermal polymerization method;

preparing magnetic CoFe2O4 by adopting a solvothermal method;

mixing the g-C3N4 and the magnetic CoFe2O4, and preparing a CoFe2O4/g-C3N4 magnetic nanocomposite material by an ultrasonic hydrothermal method; the method specifically comprises the following steps:

weighing a first mass of the g-C3N4 and a second mass of the magnetic CoFe2O4, and adding into a ceramic crucible;

adding ethanol with a first volume and ultrapure water with a second volume into the ceramic crucible, and carrying out ultrasonic treatment for a sixth time;

continuously stirring and heating in a water bath with a second water bath temperature, and evaporating to obtain a first mixture;

placing the ceramic crucible containing the first mixture in a muffle furnace, heating to a sixth temperature at a third heating speed, burning for a seventh time at the sixth temperature, and cooling to room temperature to obtain a second mixture;

and washing the second mixture with ultrapure water for multiple times, and placing the second mixture in an oven to be dried at a seventh temperature for an eighth time to obtain the CoFe2O4/g-C3N4 magnetic nanocomposite.

Preferably, the preparation of g-C3N4 by adopting a thermal polymerization method specifically comprises the following steps:

adding melamine into a ceramic crucible, putting the ceramic crucible into a muffle furnace for primary burning, setting the temperature of the primary burning to be raised to a first temperature at a first temperature raising speed, and burning for a first time;

cooling to obtain a sintered solid, and grinding the sintered solid for a first grinding time to obtain a first solid powder;

adding the first solid powder into a ceramic crucible, putting the ceramic crucible into a muffle furnace for secondary burning, setting the temperature of the secondary burning to be raised to a second temperature at a second temperature raising speed, and burning for a second time;

cooling to obtain a second solid powder, and milling said second solid powder for a second milling time to obtain said g-C3N 4.

Preferably, the preparation of the magnetic CoFe2O4 by adopting the solvothermal method specifically comprises the following steps:

dissolving Co (NO3) 2.6H 2O and Fe (NO3) 3.9H 2O in a first molar ratio in ultrapure water to obtain a solution A;

dissolving a first mass of C6H8O7 · H2O in ultrapure water so that the molar ratio of metal ions (Co2+ + Fe3 +)/citric acid is equal to 1.0, obtaining a solution B;

dropwise adding the solution A into the solution B under magnetic stirring to obtain a first mixed solution;

heating the first mixed solution in a water bath at the first water bath temperature for a third time to react to obtain a second mixed solution;

putting the second mixed solution into an oven, and drying at a fourth temperature for a fourth time to obtain gel;

and (3) burning the gel at a fifth temperature for a fifth time to obtain the magnetic CoFe2O 4.

Preferably, the first temperature rise speed is 1-3 ℃/min, the first temperature is 500-;

the second temperature rise speed is 1-3 ℃/min, the second temperature is 450-550 ℃, and the second time is 1.5-2.5 h;

the first grinding time is 15-20min, and the second grinding time is 15-20 min;

the first molar ratio is 1:1.8-1: 2.2;

the first water bath temperature is 55-65 ℃, the third time is 0.8-1.3h, the fourth temperature is 85-95 ℃, and the fourth time is 22-26 h;

the fifth temperature is 280-520 ℃, and the fifth time is 3.5-4.5 h.

Preferably, the ratio of the second mass to the first mass is 0.08: 1-0.45;

the sixth time is 25-35 min; the temperature of the second water bath is 75-85 ℃;

the third temperature rise speed is 1.5-2.5 ℃/min, the sixth temperature is 250-350 ℃, and the seventh time is 1.5-2.5 h;

the seventh temperature is 55-65 ℃, and the eighth time is 22-26 h.

Preferably, the first temperature rise speed is 2 ℃/min, the first temperature is 550 ℃, and the first time is 4 h;

the second heating speed is 2 ℃/min, the second temperature is 500 ℃, and the second time is 2 h;

the first grinding time is 20min, and the second grinding time is 20 min;

the first molar ratio is 1: 2;

the first water bath temperature is 60 ℃, the third time is 1h, the fourth temperature is 90 ℃, and the fourth time is 24 h;

the fifth temperature is 300 ℃, 400 ℃ or 500 ℃, and the fifth time is 4 hours.

Preferably, the second mass and the first mass have a ratio of 0.1:1, 0.2:1 or 0.4: 1;

the sixth time is 30 min; the temperature of the second water bath is 80 ℃;

the third heating speed is 2 ℃/min, the sixth temperature is 300 ℃, and the seventh time is 2 h;

the fifth temperature is 300 ℃; the seventh temperature is 60 ℃, and the eighth time is 24 hours.

Preferably, the CoFe2O4/g-C3N4 magnetic nanocomposite comprises the following components in percentage by weight: the mass part ratio of CoFe2O4/g-C3N4 is 0.4: 1.

According to another aspect of the invention, the magnetic nanocomposite material is also provided, and the CoFe2O4/g-C3N4 magnetic nanocomposite material is prepared by the preparation method of the magnetic nanocomposite material.

Preferably, the CoFe2O4/g-C3N4 magnetic nanocomposite comprises the following components in percentage by weight: the mass part ratio of CoFe2O4/g-C3N4 is 0.4: 1.

One of the technical schemes of the magnetic nano composite material and the preparation method thereof has the following advantages or beneficial effects: the invention takes melamine, Fe (NO3) 3.9H 2O and Co (NO3) 2.6H 2O as raw materials to prepare a CoFe2O4/g-C3N4 magnetic nano composite material, the optimal ignition temperature is 300 ℃, the optimal composite proportion is that CoFe2O4: g-C3N4(w/w) ═ 0.4:1, CoFe2O4 is uniformly attached to the surface of the flaky g-C3N4 and does not enter the crystal lattice; the magnetic nano composite material has good stability and good photocatalytic degradation effect on CIP, the degradation rate can still reach more than 90% of the initial efficiency after five times of recycling, and meanwhile, the magnetic nano composite material is quickly separated from wastewater by virtue of the magnetism of the magnetic nano composite material, so that the magnetic nano composite material is an environment-friendly photocatalytic material capable of being recycled.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without inventive efforts, wherein:

FIG. 1 is a representation of a scanning electron microscope of a prior art CoFe2O4/g-C3N4 magnetic nanocomposite;

FIG. 2 is a schematic flow chart of a preparation method of a CoFe2O4/g-C3N4 magnetic nanocomposite material according to an embodiment of the invention;

FIG. 3 is a first SEM image of a CoFe2O4/g-C3N4 magnetic nanocomposite of an embodiment of the invention;

FIG. 4 is a second SEM image of a CoFe2O4/g-C3N4 magnetic nanocomposite of an embodiment of the invention;

FIG. 5 is an XRD pattern of a CoFe2O4/g-C3N4 magnetic nanocomposite of an example of the invention;

FIG. 6 is a first XPS energy spectrum of a CoFe2O4/g-C3N4 magnetic nanocomposite of an example of the invention;

FIG. 7 is a second XPS energy spectrum of a CoFe2O4/g-C3N4 magnetic nanocomposite of an example of the invention;

FIG. 8 is a schematic diagram showing the effect of the burning temperature of CoFe2O4/g-C3N4 magnetic nanocomposite on the photocatalytic performance of the magnetic nanocomposite according to the embodiment of the present invention;

FIG. 9 is a schematic diagram showing the effect of the composite ratio of CoFe2O4/g-C3N4 magnetic nanocomposite on the photocatalytic performance of the magnetic composite nanocomposite according to the embodiment of the invention;

FIG. 10 is a graph of the effect of Catalyst/CIP ratio on photocatalytic degradation at different initial CIP concentrations for CoFe2O4/g-C3N4 magnetic nanocomposites of examples of the invention;

FIG. 11 is a schematic diagram of the effect of five cycles of experiments on CIP degradation of CoFe2O4/g-C3N4 magnetic nanocomposite material of an embodiment of the invention;

FIG. 12 is (a) the fluorescence spectrum of p-hydroxybenzoic acid during light irradiation and (b) the PL profile of g-C3N4 and CoFe2O4/g-C3N4 for CoFe2O4/g-C3N4 magnetic nanocomposite material of examples of the present invention.

Detailed Description

In order that the objects, aspects and advantages of the present invention will become more apparent, various exemplary embodiments will be described below with reference to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration various exemplary embodiments in which the invention may be practiced, and in which like numerals in different drawings represent the same or similar elements, unless otherwise specified. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. It is to be understood that they are merely examples of methods consistent with certain aspects of the present disclosure as detailed in the appended claims, and that other embodiments may be used or methodological and functional modifications may be made to the embodiments recited herein without departing from the scope and spirit of the present disclosure. In other instances, detailed descriptions of well-known methods and products are omitted so as not to obscure the description of the present invention with unnecessary detail.

The following embodiment is merely a specific example and does not indicate such an implementation of the present invention. In order to explain the technical means of the present invention, the following description will be given by way of specific examples.