CN109529776B

CN109529776B - Graphene oxide-cerium hydroxide composite material, preparation method and application thereof

Info

Publication number: CN109529776B
Application number: CN201910048216.8A
Authority: CN
Inventors: 闫海刚; 黄鸿淮; 蔡舒雅; 魏诗佳; 詹峰萍
Original assignee: Minnan Normal University
Current assignee: Minnan Normal University
Priority date: 2019-01-18
Filing date: 2019-01-18
Publication date: 2021-12-14
Anticipated expiration: 2039-01-18
Also published as: CN109529776A

Abstract

The invention discloses a graphene oxide-cerium hydroxide composite material, a preparation method and application thereof. In the experiment, the graphene oxide-cerous hydroxide composite material (Ce (OH) is prepared by a direct precipitation method and a hydrothermal synthesis method₄/GO) is used for adsorbing and removing Congo Red (CR) and phosphate radical ions (PO) in solution₄ ^3‑) And the structure of the composite material is characterized by SEM, FT-IR and the like, and Congo Red (CR) and phosphate ions (PO) are subjected to conditions of different pH, temperature, initial mass concentration and the like₄ ^3‑) The adsorption effect of (A) is discussed, and the optimal adsorption conditions are determined as follows: the pH was 7.0 and 6.0, the adsorption time was 6 hours, and the temperature was 50 ℃ and 30 ℃. Congo red and PO were obtained by Langmuir model analysis₄ ^3‑The maximum adsorption amounts of the components are 563.67mg/g and 619.63mg/g respectively, and the adsorption effect is obvious.

Description

Graphene oxide-cerium hydroxide composite material, preparation method and application thereof

[ technical field ] A method for producing a semiconductor device

The invention belongs to the technical field of water treatment agent preparation, and particularly relates to a graphene oxide-cerium hydroxide composite material, a preparation method and application thereof.

[ background of the invention ]

There are many wastewater treatment techniques such as flocculation, membrane filtration, solvent extraction, biosorption, chemical precipitation, ion exchange, reverse osmosis, electrocoagulation, sintering, electroprecipitation, coagulation, and adsorption. Among them, the adsorption method has become a widely used method for removing pollutants with the advantages of low production cost and simple operation and treatment process, and it is very important to design a novel adsorbent having excellent adsorption capacity.

There are many types of adsorbents, which can be mainly classified into 3 types:

the first type is the more common porous adsorption materials, such as activated carbon, zeolite, adsorption resin, and the like.

The second type is non-porous adsorption material, which is less researched at present and mainly comprises fiber materials (such as glass fiber, cotton fiber, chemical fiber and the like), biological materials (such as algae, chitosan, mycelium, activated sludge and the like) and mineral materials (such as kaolin and magnetite) and the like.

The third type is a nano-adsorbent material, which has been the focus of environmental workers in recent years because of its generally large specific surface area and good surface adsorption activity. The most studied are carbon nanotubes, (oxidized) graphene, fullerenes, titanium dioxide nanotubes, etc.

Graphene oxide is as the two-dimensional material of a neotype individual layer carbon atom thickness, its surface song contains multiple active group, mainly include a large amount of hydroxyl, carboxyl, oxygen-containing functional groups such as epoxy are on its surface, the existence of these active oxygen-containing groups can provide necessary adsorption site for the pollutant, great improvement GO's solubility, can effectually avoid taking place the reunion phenomenon, GO mainly lies in the effort that takes place between its zwitterion to various dyestuff and metallic ion's adsorption efficiency, so GO has superior adsorption performance, it has very big application prospect to handle dyestuff waste water, but graphene oxide after the absorption will dissolve in aqueous, hardly draw out from the solvent, can not reuse, cause very big waste.

Therefore, the recyclable novel graphene oxide-based metal compound composite adsorbent becomes a new hotspot.

Various (oxy) graphene-based metal compound nanomaterials have been synthesized to date, including with TiO₂、ZnO、MnO₂、CeO₂、Fe₃O₄、Zn-Fe₃O₄、Ag₃PO₄、Bi₂WO₆And the like. The synthesized graphene oxide-rare earth compound composite material is still rare as an adsorbent. The direct precipitation method is the most commonly used method of preparation. By sol-gel method, hydrothermal/solventThe graphene oxide-metal oxide composite material prepared by the methods of thermal method, electrochemical deposition, microwave-assisted growth and the like also achieves good effects.

Cerium is a silver gray active metal, and the powder is easy to spontaneously combust in air, is easy to dissolve in acid and has the highest abundance in rare earth elements. Used as alloy additive, reducer, cerium salt, etc. and in medicine, leather, glass, textile and other industries. The cerium oxide is light yellow or yellow brown auxiliary powder. Density 7.13g/cm³. Melting point 2397 deg.C. Insoluble in water and alkali, slightly soluble in acid, and can be used as polishing material, catalyst carrier (assistant), ultraviolet absorbent, fuel cell electrolyte, automobile tail gas absorbent, electronic ceramic, etc.

In summary, the metal compound loaded on the graphene oxide composite adsorbent is mainly ZnO and MnO₂、CeO₂、Fe₃O₄Etc. No Ce (OH) load was observed₄The report of (1). Magnetic adsorbents (Fe) mainly reported as rare earth adsorbents₃0₄@Y(OH)CO₃With Fe₃0₄@CeO₂.nH₂0) And rare earth lanthanum oxide on zeolite, but not combined with graphene oxide. Therefore, the rare earth compound is agglomerated, the specific surface area is reduced, the adsorption sites are reduced, and the adsorption effect is far lower than the effect of the synergistic effect generated by uniformly loading the rare earth compound on the graphene oxide.

[ summary of the invention ]

The invention provides a graphene oxide-cerium hydroxide composite material, a preparation method and application thereof, and aims to solve the practical technical problems of low adsorption effect and the like.

In order to solve the technical problems, the invention adopts the following technical scheme:

a preparation method of a graphene oxide-cerous hydroxide composite material comprises the following steps:

(1) mixing GO and deionized water, and then carrying out ultrasonic dissolution to obtain a dissolved solution;

(2) adding Ce (NO) into the solution prepared in the step 1₃)₃At 60 ℃ CStirring and reacting for 0.5h to prepare a mixed solution a;

(3) adding 20ml of urea solution into the mixed solution a prepared in the step 2, and stirring for more than 2 hours at 90 ℃ to prepare mixed solution b;

(4) cooling the mixed solution b prepared in the step (3) to room temperature, adding NaOH, and stirring to prepare a mixed solution c;

(5) carrying out centrifugal separation on the mixed solution c prepared in the step 4, washing to obtain an initial product, mixing the initial product with 80 ml of a 1M urea solution and ethanol mixed solution, transferring the mixture into a hydrothermal reaction kettle, reacting for 48 hours at 90 ℃, and after the reaction is finished, cooling the reaction kettle to room temperature and taking out to obtain a product;

(6) and (3) filtering the product obtained in the step (5), washing the product with ethanol and deionized water to be neutral, drying the filtered product in a vacuum oven, and transferring the dried product into another oven for drying to obtain the graphene oxide-ceric hydroxide composite material.

Further, the ultrasonic dissolution in the step 1 is realized by ultrasonic treatment for 0.5h under the power of an ultrasonic cleaning machine of 100W.

Further, the concentration of the urea solution in the step 3 is 2 mol/L.

Further, the conditions for drying in the vacuum oven described in step 6: drying at 60 deg.C for 24 h.

Further, the conditions for moving into another oven for drying in step 6 are as follows: drying at 85 deg.C for 12 h.

The invention also provides the graphene oxide-cerium hydroxide composite material prepared by the method.

The invention also provides an application of the graphene oxide-cerium hydroxide composite material, which is applied to the technical field of wastewater treatment and used as an adsorbent.

The invention has the following effects:

(1) in the experiment, the graphene oxide-cerous hydroxide composite material (Ce (OH) is prepared by a direct precipitation method and a hydrothermal synthesis method₄/GO) is used for adsorbing and removing Congo Red (CR) and phosphate radical ions (PO) in solution₄ ^3-) And the structure of the composite material is characterized by SEM, FT-IR and the like, and is characterized by different pH values and temperaturesAnd initial mass concentration of Congo Red (CR) and phosphate radical ion (PO)₄ ^3-) The adsorption effect of (A) is discussed, and the optimal adsorption conditions are determined as follows: the pH was 7.0 and 6.0, the adsorption time was 6 hours, and the temperature was 50 ℃ and 30 ℃. Congo red and PO were obtained by Langmuir model analysis₄ ^3-The maximum adsorption amounts of the adsorbent are 563.67mg/g and 619.63mg/g respectively, the adsorption effect is obvious and far exceeds the adsorption effect of adsorption materials reported in many documents.

(2) According to the invention, a direct precipitation method and a hydrothermal/solvothermal method are combined to synthesize the GO-ceric hydroxide composite material for adsorbing the dye and the phosphate radical, and the result shows that the GO-ceric hydroxide composite material has an obvious effect far exceeding that of many similar adsorbents. The reason is that the GO also weakens the pi-pi acting force between own lamellar layers while loading rare earth, so that various composite materials with high dispersion and excellent performance can be prepared, and the physical and chemical properties of the composite materials are improved due to the synergistic effect formed among the components in the reaction process.

(3) The method has simple process and high experimental result reproduction rate, and can obtain products with stable performance.

[ description of the drawings ]

FIG. 1 is a schematic process flow diagram of the present invention;

FIG. 2 is a scanning electron micrograph of graphene oxide;

FIG. 3 is an SEM image provided by an implementation of the invention;

FIG. 4 is the FT-IR diagram of GO;

FIG. 5 is Ce (OH)₄FT-IR plot of/GO composite;

FIG. 6 is a graph showing the effect of solution pH on Congo Red adsorption;

FIG. 7 is a graph of the effect of different initial mass concentrations on Congo red adsorption;

FIG. 8 is a graph showing the effect of adsorption temperature on Congo red adsorption capacity;

FIG. 9 is solution pH vs. PO₄ ^3-A graph of the effect of adsorption;

FIG. 10 is different mass concentrations versus PO₄ ^3-A graph of the effect of adsorption;

FIG. 11 isAdsorption temperature to PO₄ ^3-A graph of the effect of adsorption;

FIG. 12 is Ce (OH)₄Graph for recycling of/GO composites.

■: cyclic regeneration ● of adsorbed congo red: cyclic regeneration of adsorbed phosphate radicals

[ detailed description ] embodiments

First, experimental part

1. Main raw materials and apparatus

The test materials provided by the implementation of the invention are as follows: graphene Oxide (GO) (AA, Suzhou carbon-rich science and technology Co., Ltd.), cerium nitrate (Ce (NO)₃)₃) (AR, national chemical Agents Co., Ltd.), sodium hydroxide (NaOH) (AR, Guangdong. Shantou Kao Kagaku Co., Ltd.), hydrochloric acid (HCl) (AR, Sjogaku Kagaku Co., Ltd.), and ethanol (C)₂H₅OH) (AR, Szelong science, Inc.), ammonium molybdate tetrahydrate ((NH)₄Mo₇O₂₄.4H₂O) (AR, Kyosu science, Inc.), Potassium dihydrogen phosphate (KH)₂PO₄) (AR, Szegaku K.K.), L (+) -ascorbic acid (C)₆H₈O₆) (AR, Szelong scientific Co., Ltd.) Congo Red (C)₃₂H₂₂N₆Na₂O₆S₂) (AR, Sjogren science, Inc.).

The implementation of the invention provides the following instruments: scanning Electron Microscope (SEM), X-ray diffraction spectrometer (XRD), HH-4 digital display constant temperature water bath, DF-101S heat collection type constant temperature heating magnetic stirrer, three-neck reaction bottle, 756PC type ultraviolet visible spectrophotometer (Shanghai spectrometer Co., Ltd.), PERKIN-ELMER FTIR 1710 type Fourier transform infrared spectrometer, fine macro vacuum drying box DZF-6030, spherical condenser tube, magnetic stirring balance, ultrasonic cleaner, analytical instrument, multi-head magnetic heating stirrer, air blowing drying box and pH meter.

2. Experimental protocol

Ce(OH)₃the/GO composite material preparation process is shown in figure 1. The preparation process comprises the following steps: 0.2g of GO was dissolved in a three-necked flask with 200mL of deionized water and passed through an ultrasonic cleaner,ultrasonic treating at 100W for 0.5 hr, and adding 0.8g of Ce (NO)₃)₃Stirring and reacting for 0.5h at the temperature of 60 ℃; adding 20ml of urea solution with the concentration of 2mol/L into the mixed solution, stirring and heating to about 90 ℃ and keeping the temperature for more than 2 hours to completely precipitate the urea solution, cooling to room temperature, adding 10ml of 1M NaOH, stirring for 1 hour, centrifugally separating and washing the synthesized initial product, transferring the obtained product, 80 ml of 1M urea solution and ethanol mixed solution into a hydrothermal reaction kettle (100ml, 80% filling rate and 20ml of space reserved) to react for 48 hours at 90 ℃, after the reaction is finished, taking out the reaction kettle after cooling to room temperature, filtering the product, washing the product to be neutral by using ethanol and deionized water, drying the filtrate in a vacuum oven at 60 ℃ for 24 hours, then drying in an oven at 85 ℃ for 12 hours, and preparing the graphene oxide-cerium hydroxide composite material (Ce (OH)₃a/GO composite).

3、Ce(OH)₃Determination of adsorption performance of/GO composite material

3.1 adsorption experiment of Congo Red by composite Material

Adding 0.02g of composite adsorbent into a conical flask containing 100mL of water, dispersing for about 10min by an ultrasonic machine, and adding different volumes of to-be-adsorbed solution (5mmol/L Congo red stock solution). The pH value of the solution is adjusted to 7.0 by adding HCl or NaOH, the total volume of the solution is 200mL, and the solution is placed in a multi-head magnetic heating stirrer and added with the magnet to react for 12 h. After the reaction, a certain amount of the mixture was measured for the concentration of congo red in water by a UV-vis spectrophotometer at a detection wavelength of max 498 nm. The results obtained by adsorption were fitted by a Langmuir model, and the adsorption performance thereof was analyzed and the maximum adsorption amount thereof was determined from the obtained adsorption data.

The concentration of congo red can be analyzed by an ultraviolet-visible spectrophotometer. The result can be calculated from equation (1):

q＝(C₀—C_e)V/m (1)

C₀、C_e: initial and equilibrium concentrations of solution (mg. L)

m: mass of adsorbent (g) V: volume of solution (L)

3.2 composite Pair PO₄ ^3-Adsorption experiment of

Adding 0.02g of composite adsorbent into a conical flask containing 100mL of water, dispersing for about 10min by an ultrasonic machine, and adding different volumes of to-be-adsorbed solution (0.5mg/mL potassium dihydrogen phosphate stock solution). The pH of the solution is adjusted by HCl or NaOH, the total volume is fixed to 200mL, and the solution is placed in a multi-head magnetic heating stirrer and added with a magnet to react for 12 h. After the reaction, a certain amount of the mixture was added with 2ml of ammonium molybdate and 3ml of ascorbic acid, and PO in water was detected by UV-vis spectrophotometer₄ ^3-The detection wavelength is 710 nm. The adsorption results were fitted by Langmuir model. And analyzing the adsorption performance of the adsorption material according to the obtained adsorption data, and determining the maximum adsorption quantity.

PO₄ ^3-Can be calculated from the above formula (1).

The invention is further described below in connection with the results and analysis:

second, result and discussion

2.1 GO and Ce (OH)₃Material characterization of/GO composites

2.1.1 Scanning Electron Microscope (SEM)

From fig. 2, it can be observed that the graphene oxide exhibits a lamellar structure, like a ribbon. The sheet layer is very thin, and graphene oxide with different sizes can be seen on the edge due to ultrasonic shedding, because GO is good in dispersibility and uniformly dispersed in water.

From FIG. 3, we can see the clay-like Ce (OH)₄Supported on GO, has obvious agglomeration phenomenon, and is loaded with Ce (OH)₄The GO sheets of (A) exhibit small pores due to Ce (OH)₄The specific surface area of the/GO composite material is increased, the number of active sites is increased, and the GO also weakens the pi-pi acting force between the sheets of the GO when loading rare earth, so that the composite material with high dispersion and excellent performance can be prepared, and the components form a synergistic effect with each other in the reaction process, thereby overcoming the defects of the traditional material and improving the physical and chemical properties of the traditional material.

2.1.2 Fourier transform Infrared Spectroscopy (FT-IR)

As seen from FIG. 4, the O-H stretching vibration peak of GO is 3385cm^-1And 1220cm^-1Here, this is represented by sp²The C-O-C stretching vibration peak, the C-OH stretching vibration peak and the C ═ C stretching vibration peak caused by carbon bones are 1045cm respectively^-1，1374cm^-1And 1619cm^-1At 1725cm^-1The peak indicates that GO contains oxygen-containing functional groups such as carboxyl, hydroxyl, and epoxy groups.

Ce (OH) shown in FIG. 5₄the/GO samples respectively show O-H (3449 cm)^-1) Stretching vibration of (2), O-H (3192 cm) in carboxyl group^-1) Stretching vibration, and antisymmetric stretching vibration of C ═ O in carboxylate at 1575cm^-1And symmetric telescopic vibration at 1385cm^-1Infrared characteristic absorption peak of the isofunctional group, which indicates that the supported Ce (OH)₄And then, a large number of carboxyl groups on the surface of GO are combined with Ce ions to form chemical bonds, and characteristic peaks of other various functional groups on the surface of GO are obviously weakened or disappear. Thus, it can be concluded that graphene oxide is associated with Ce (OH)₄Has good interface compatibility, is combined by chemical bonds and has good loading effect.

2.2 results of composite on Congo Red adsorption

Effect of pH 2.2.1 on Acidoxum Red

The influence of pH on the adsorbent is very large, and therefore, selecting a suitable pH is one of the prerequisites for obtaining the maximum adsorption amount of the adsorbent. Selecting the initial Congo red mass concentration as 16.5mg.L^-1The adsorption time is 6h, the adsorption temperature is 25 ℃, and the pH value is opposite to that of Ce (OH)₃The effect of/GO adsorption Congo Red is shown in FIG. 6: the pH value is obviously increased from 5 to 7, the adsorption quantity is rapidly reduced from 7 to 9, the optimal adsorption pH value is 7, Ce (OH)₄The adsorption effect of/GO on Congo red dye is caused by the combined action of a plurality of reactions:

1. when the solution has a pH of 7, Ce (OH)₃the/GO surface is positively charged, while CR is an anionic dye, negatively charged, Ce (OH)₃The effect of GO on CR is electrostatic adsorption;

2. when the pH is higher<7 th hour, excess H⁺In combination with anionic dyesThe adsorption of adsorption sites is affected, so that the adsorption performance of the adsorbent is poor at low pH;

3. when the pH is higher>At 7, the adsorption performance is lowered due to OH^AThe presence of (A) is not favorable for reduction of azo bonds, the negative charge on the surface of the adsorbent is gradually increased, the adsorbent is repelled with Congo red with the same negative charge, and the adsorbent competes with CR anions for adsorption sites.

Therefore, the adsorption effect is best when the pH is about 7.

2.2.2 Effect of initial Mass concentration on adsorbed Congo Red

Under the operating conditions that the pH of the solution is selected to be 7, the adsorption time is selected to be 6h, and the adsorption temperature is selected to be 25 ℃, the influence of the initial Congo red mass concentration on the Congo red adsorption amount is shown in FIG. 7, along with the continuous increase of the initial Congo red mass concentration, the Congo red adsorption amount is increased, the adsorption amount is increased quickly, and the adsorption amount is increased slowly when a certain concentration is reached. When the content of the adsorbent is fixed, along with the continuous increase of the Congo red mass concentration, the effective collision probability of the Congo red adsorbent and Congo red adsorbent is increased, and the adsorption capacity is also increased. When the adsorption of the adsorbent reaches saturation, adsorption sites on the surface of the adsorbent are completely occupied by the adsorbate, and the adsorption amount reaches equilibrium at the moment and does not increase obviously.

2.2.3 Effect of temperature on Congo Red adsorption

At an optimum pH of 7, the initial mass concentration was chosen to be 266.29mg.g^-1The adsorption time was selected to be 6 hours, and the effect of the adsorption temperature on the adsorption amount of congo red is shown in fig. 8: at an adsorption temperature of 30-50 ℃, Ce (OH)₃The adsorption capacity of the/GO composite material is slowly increased, but at 50-60 ℃, the adsorption capacity tends to be balanced along with the increase of the temperature, the adsorption capacity begins to gradually decrease, and under the condition of about 50 ℃, the adsorption capacity reaches the maximum, the adsorption effect is the best, so that the optimal adsorption temperature is selected to be 50 ℃.

2.2.4 adsorption isotherm of Congo Red adsorbed by composite Material

In this experiment, we describe the composite Ce (OH) under optimal adsorption conditions using the Langmuir isothermal adsorption equation (see equation (2))₄GO to Congo RedAnd (4) an adsorption process.

ρ_e/q_e＝ρ_e/q_m+1/bq_m (2)

ρ_e: the mass concentration of Congo red in the solution during adsorption equilibrium is mg/L

q_e: equilibrium adsorption amount, mg/g q_m: saturated adsorption amount, mg/g

b: langmuir adsorption coefficient, L/mg

TABLE 1 fitting results of isothermal adsorption equation

As can be seen from Table 1, R of Langmuir isothermal adsorption equation²Is 0.9987, can be accurately adjusted to Ce (OH)₄Describing the adsorption process of the/GO composite material for adsorbing the Congo red, the saturated adsorption quantity of the Congo red is 563.67mg/g according to the Langmuir isothermal adsorption equation.

2.2.5 nodules

Experiments show that the optimal pH value of the solution adsorption is selected to be 7, the adsorption time is selected to be 6h, and the optimal adsorption temperature is selected to be 50 ℃. Selecting the adsorption temperature to be 25 ℃, and using Ce (OH)₃the/GO composite material is used as an adsorbent to treat Congo red solutions with different initial mass concentrations, the Congo red with different concentrations and corresponding adsorption amounts are substituted into a Langmuir isothermal adsorption equation, and the maximum saturated adsorption amount of the Congo red is 563.67mg/g through fitting. The adsorption effect is obvious and greatly exceeds the adsorption amount of the composite material reported in the literature.

2.3 composite Pair PO₄ ^3-Discussion of adsorption results

2.3.1 composite Pair PO₄ ^3-Adsorption experiment of

Adding 0.02g of composite adsorbent into a conical flask containing 100mL of water, dispersing for about 10min by an ultrasonic machine, and adding different volumes of to-be-adsorbed solution (0.5mg/mL potassium dihydrogen phosphate stock solution). Adjusting pH of the solution to 5.6 with HCl or NaOH, fixing the total volume to 200mL, placing in a multi-head magnetic heating stirrer, and magnetizingStone reaction for 12 h. After the reaction, a certain amount of the mixture was added with 2ml of ammonium molybdate and 3ml of ascorbic acid, and PO in water was detected by UV-vis spectrophotometer₄ ^3-The detection wavelength is 710 nm. The adsorption results were fitted by Langmuir model. And analyzing the adsorption performance of the adsorption material according to the obtained adsorption data, and determining the maximum adsorption quantity.

PO₄ ^3-Can be calculated from the above formula (1).

2.3.2 pH vs. adsorbed PO₄ ^3-Influence of (2)

The influence of pH on the adsorbent is great, and therefore, selecting a suitable pH is one of the prerequisites for obtaining the maximum adsorption amount of the adsorbent. In selecting the initial PO₄ ^3-The mass concentration is 53.52mg.L^-1The adsorption time is 6h, the adsorption temperature is 25 ℃, and the pH is opposite to Ce (OH)₄The effect of/GO is shown in FIG. 9 below: the adsorption capacity gradually increased at pH 5-6, and the adsorption capacity rapidly decreased at pH 6-9, which resulted in an optimum pH of 6.0, at which the maximum adsorption capacity was 513mg^-1. This is due to Ce (OH)₄PO adsorption by GO₄ ^3-Is the result of the interaction of several reactions: since the rare earth metal has positive charge, the PO with negative charge₄ ^3--Has larger adsorbability, large GO specific surface area and more active sites, but La (OH) due to pH of 5-6₃Enhanced protonation of oxygen-containing functional group of/GO with PO₄ ^3-The interaction between the two is enhanced, so that the adsorption capacity is strong, and the optimal adsorption pH of the selected solution is about 6.0.

2.3.3 concentration vs. adsorbed PO₄ ^3-Influence of (2)

Under the conditions that the pH value of the solution is 6.0, the adsorption time is selected to be 6h, and the adsorption temperature is selected to be 25 ℃, the initial PO₄ ^3-Mass concentration to PO₄ ^3-The effect of the amount of adsorption is shown in FIG. 10, with initial PO₄ ^3-Increasing mass concentration, PO₄ ^3-The adsorption amount of (A) is increased, and when the content of the adsorbent is constant, the content of the adsorbent is increased along with the PO₄ ^3-Increasing mass concentration of the compound with PO₄ ^3-The effective collision probability of (2) is increased and the adsorption amount is increased. When the adsorption capacity reaches saturation, adsorption sites on the surface of the adsorbent can be completely occupied by the adsorbate, the adsorption capacity can reach balance, the volume of the stock solution of the phosphate radical gradually tends to be flat after reaching 30mL, and the maximum adsorption capacity at the moment is close to 600mg^-1。

2.3.4 temperature vs. PO adsorption₄ ^3-Influence of (2)

The optimum pH of the solution was selected to be 6.0 and the initial mass concentration was selected to be 49.3mg.L^-1And the adsorption time is selected to be 6h, and experiments at various temperatures are carried out, wherein the adsorption temperature is opposite to PO₄ ^3-FIG. 11 shows the influence of the adsorption amount of Ce (OH)₄the/GO adsorbent is gradually reduced along with the continuous increase of the adsorption temperature of the experiment, and finally tends to be stable. The following is obtained by the graph: the adsorption temperature is selected to be 30 ℃ as the optimal adsorption temperature, and the adsorption effect is optimal.

2.3.5 composite adsorption of PO₄ ^3-Adsorption isotherm of

In this experiment, we used the Langmuir isothermal adsorption equation (see equation (2)) to describe the optimum adsorption conditions for Ce (OH)₄PO of/GO composite material₄ ^3-The adsorption process of (1).

TABLE 2 fitting results of isothermal adsorption equation

As can be seen from Table 2, R of Langmuir isothermal adsorption equation²0.9895 for La (OH)₃PO adsorption of/GO composite material₄ ^3-The adsorption process of (A) is accurately described, and the saturation adsorption quantity obtained by fitting a Langmuir isothermal adsorption equation is 619.63 mg/g.

2.3.6 small knot

The above experiments concluded that the solution had an optimum adsorption pH of 6.0, an adsorption time of 6h and an optimum adsorption temperature of 30 ℃. Ce (OH)₄the/GO composite material is used as an adsorbent to treat PO with different initial mass concentrations₄ ^3-Solution, 25 ℃, different concentrations of PO₄ ^3-And substituting the corresponding adsorption amount into Langmuir isothermal adsorption equation, fitting to obtain the maximum saturated adsorption amount of 619.63mg/g, and keeping the recovery rate above 80% after cyclic adsorption for 6 times. The adsorption effect is obvious and greatly exceeds the adsorption amount of the composite material reported in the literature.

2.4 Cyclic regeneration of Congo Red and phosphate solution adsorbed by composite Material

The adsorbent is used as a main role for treating water pollution in daily life, and is required to be efficient and rapid, mainly characterized by cyclic regeneration, namely Ce (OH)₄After the first adsorption of Congo red, soaking the composite material in ethanol for 2 days, washing the composite material with deionized water for several times, drying the composite material in a blast drying oven, and recycling the composite material; primary pair of PO of composite material₄ ^3-After the solution is adsorbed, soaking the solution in NaOH solution for 2 days, washing the solution with deionized water for a plurality of times, drying the solution in a blast drying oven, and recycling the solution. As can be seen from FIG. 12, the adsorbent recovered after 6 cycles had a reduced adsorption rate, but still had a rate of 80% or more, so that Ce (OH)₄the/GO adsorbent can be repeatedly recycled.

Third, conclusion

In the experiment, Ce (OH) is prepared by a direct precipitation method and hydrothermal synthesis₄the/GO composite material adopts an adsorbent which is quick, efficient, simple in process and free of secondary pollution to Congo red and PO₄ ^3-Adsorption studies were performed, and the optimum adsorption conditions obtained by exploring the contaminants for pH, temperature, and initial mass concentration were: the pH was 7 and 6.0, the adsorption time was 6 hours, and the temperature was 50 ℃ and 30 ℃. Congo red and PO were obtained by Langmuir model analysis₄ ^3-The maximum adsorption amounts of the adsorbent are 563.67mg/g and 619.63mg/g respectively, the adsorption effect is obvious, the adsorbent can be recycled, and the adsorption amount is far more than that of the adsorption material reported in the literature (see the following table)2 and 4), is expected to become an efficient and green adsorbent for removing dye and phosphorus pollution in the water pollution treatment process.

TABLE 3 saturated adsorption capacity of Congo Red (CR) by different adsorbents

TABLE 4 saturated adsorption capacity of different adsorbents for phosphate radical

Reference documents:

[1] deep in the Neihai, hierarchical structure boehmite composite preparation and adsorption performance study [ D ]. Chongqing university of science 2015.

[2] Zhanli, the modified graphene oxide/chitosan composite material was studied on the adsorption of hexavalent chromium and congo red in water [ D ]. university of south china, 2016.

[3] Li ze wood, Pengxing spring, Wang Qing Hua, Chua hong, Li you Jiu, preparation of dendritic macromolecule coating Co nano composite material using graphene as core and its adsorption property [ J ]. fine chemical industry, 2016,33(02): 200-.

[4] DUQJ, SUNJK, LIYII, ethanol, high affinity enhanced adsorption of bound to graphene oxide/ch ito-fibers by wet-Chemical off-silicas [ J ]. Chemical Engineering Journal,2014,245 (6): 99 to 106.

[5] Li epi, preparation of functionalized magnetic graphene adsorbing material and performance study [ D ]. university of jonan 2015.

[6]Yao Y，Miao S，Liu S，et a1.Synthesis，characterization，and adsorption properties ofmagnetic Fe₃O₄@graphene nanocomposite[J].Chem Eng J，2012，184：326

[7] Wu Yan, synthesis of graphite nano composite material and study of adsorption and photocatalytic performance thereof [ D ], [ doctor's thesis ]. Guangzhou: university of southern China, 2016

[8] Qianminbi, bayonghong, maja-meyeriana preparation of lanthanum titanium modified bentonite adsorbent and research on phosphorus removal performance [ J ] application chemical industry, 2008, 37 (1): 54-66

[9] Wujiao, synthesis and adsorption mechanism research of magnetic rare earth efficient phosphorus removal agent [ D ], [ doctor academic thesis ]. Changchun: northeast university, 2014.

[10] Zhang Zijie wastewater treatment theory and design [ M ] Beijing, Chinese architecture industry Press, 2002: 470-.

[11] Yangxian, Zhou Jia, Chenya et Al Zn-Al hydrotalcite and its roasted product are used in research on the adsorption of phosphorus in water [ J ] industrial water treatment, 2011,31(10):53-56.

[12] Electrowinning to prepare a porous light rare earth dephosphorizing adsorbent and performance research [ D ], [ doctor's thesis ]. guangzhou: river university, 2015

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. To those skilled in the art to which the invention relates, numerous changes, substitutions and alterations can be made without departing from the spirit of the invention, and these changes are deemed to be within the scope of the invention as defined by the appended claims.

Claims

1. The preparation method of the graphene oxide-cerous hydroxide composite material is characterized by comprising the following steps:

(2) adding Ce (NO) into the solution prepared in the step 1₃)₃Stirring and reacting for 0.5h at the temperature of 60 ℃ to prepare a mixed solution a;

(3) adding 20ml of urea solution into the mixed solution a prepared in the step 2, wherein the concentration of the urea solution is 2mol/L, and stirring at 90 ℃ for more than 2 hours to prepare mixed solution b;

(5) transferring the initial product obtained by centrifugally separating and washing the mixed solution c prepared in the step 4 and 80 ml of the mixed solution of 1M urea solution and ethanol into a hydrothermal reaction kettle, reacting for 48 hours at 90 ℃, and after the reaction is finished, taking out the mixed solution after the reaction kettle is cooled to room temperature to obtain a product;

2. The method for preparing the graphene oxide-cerous hydroxide composite material according to claim 1, wherein: the ultrasonic dissolution in the step 1 is realized by ultrasonic treatment for 0.5h under the power of an ultrasonic cleaning machine of 100W.

3. The method for preparing the graphene oxide-cerous hydroxide composite material according to claim 1, wherein: conditions for drying in a vacuum oven as described in step 6: drying at 60 deg.C for 24 h.

4. The method for preparing the graphene oxide-cerous hydroxide composite material according to claim 1, wherein: the conditions for moving to another oven for drying in step 6 are as follows: drying at 85 deg.C for 12 h.

5. A graphene oxide-ceric hydroxide composite prepared according to the method of any one of claims 1-4.

6. The application of the graphene oxide-cerous hydroxide composite material according to claim 5, wherein: is applied to the technical field of wastewater treatment and is used as an adsorbent.