CN111437792A - Synthetic method of magnetic mesoporous silica for removing copper ions in water - Google Patents

Abstract

The invention belongs to the technical field of water pollution treatment application, and particularly relates to a synthetic method of magnetic mesoporous silica for removing copper ions in water. The preparation method comprises the steps of synthesizing Fe3O4 nano-particles by using ionic liquid, taking Fe3O4 nano-particles as seeds, slowly dripping TEOS under a heating condition to form nuclei, then synthesizing Fe3O4@ SiO2 by taking CTAB as a template agent, and finally removing the template agent to obtain the mesoporous silica taking Fe3O4 as a magnetic nucleus. The necessity of synthesizing Fe3O4@ SiO2 core is proved by experiments. And finally, removing trace copper ions in the water body by using mesoporous Fe3O4@ SiO2 with a core-shell structure. The result shows that a large number of mesoporous structures exist on the surface and inside of the magnetic mesoporous silica, and the magnetic mesoporous silica has stronger adsorption capacity to copper ions when the pH is 6 and the temperature is 60 ℃; the adsorption time is about 7h, and the adsorption capacity of the magnetic mesoporous silica to copper ions is saturated.

Description

Synthetic method of magnetic mesoporous silica for removing copper ions in water

Technical Field

The invention belongs to the technical field of water pollution treatment application, and particularly relates to a synthetic method of magnetic mesoporous silica for removing copper ions in water.

Background

With the development of modern industry, the nature is polluted by a large amount of heavy metal wastewater. The problem of heavy metal pollution of water in China is very outstanding, and heavy metal wastewater causes serious harm to biological health after being discharged into natural water. Copper is a heavy metal which has wide application and recovery value in industrial production, and it is very important to explore the effective treatment and recovery of copper in wastewater.

The existing methods for treating copper-containing wastewater mainly comprise a physical adsorption method, a chemical precipitation method, an ion exchange method, an electrolysis method, a membrane separation method and the like. Among them, the adsorption method is widely used because of its advantages of high efficiency, economy, greenness, etc. The traditional adsorbent generally has the problems of high regeneration cost, short service life, difficulty in recovering heavy metal resources and the like, and particularly when the concentration of Cu2+ is very low, a macroscopic adsorption interface is often difficult to effectively remove trace metal ions in a short time. Therefore, the preparation of a novel adsorbent which is high in efficiency, low in cost and easy to recover is of great significance.

The magnetic adsorption material is a research hotspot at present, can be easily separated from a solution under the condition of using an external magnetic field, can be repeatedly used, and has wider application in water treatment. Magnetic nanoparticles, particularly Fe3O4, have attracted considerable attention in recent years due to their exceptional magnetic properties, biocompatibility, low toxicity, and ease of economical synthesis processes. In addition, because the external magnetic field of the Fe3O4 magnetic nanoparticles has no external diffusion resistance, high activity, high surface area and quick recovery from a liquid phase, the Fe3O 4-based nanomaterial is classified as a promising adsorbent for removing pollutants in wastewater, and has a good application prospect in deep treatment of heavy metal ions.

At present, the number of the current day,

the most commonly used method for modifying SiO2 on the surface of Fe3O4 nanoparticles is that based on sol-gel reaction, Fe3O4 nanoparticles are used as seeds, and in an alcohol/water solution system, ethyl orthosilicate (TEOS) is hydrolyzed and condensed in an alkaline environment by adding ammonia water, and the generated SiO2 is coated on the surfaces of the seeds. Compared with other SiO2 modification methods,

the method has the characteristics of simple operation, low cost, high coating rate and the like, but the size of the prepared particles is difficult to control, and the particle size distribution is not uniform.

Disclosure of Invention

Aiming at the technical problems that the particle size is difficult to control and the particle size distribution is not uniform, the invention provides a method for synthesizing magnetic mesoporous silica for removing copper ions in water, which is simple, convenient to operate and good in effect of removing copper ions.

In order to achieve the above object, the present invention adopts a technical scheme that the present invention provides a method for synthesizing magnetic mesoporous silica for removing copper ions in water, comprising the following steps:

a. firstly, accurately weighing FeCl3 & 6H2O in a beaker, and dissolving the FeCl3 & 6H2O in a mixed solution of 1-butyl-3-methylimidazole tetrafluoroborate and H2O in a volume ratio of 1:1 to obtain a 1.00 mol/L FeCl3 solution for later use;

b. accurately weighing FeSO4 & 7H2O in a beaker, and dissolving the FeSO4 & 7H2O in a mixed solution of 1-butyl-3-methylimidazolium tetrafluoroborate and H2O in a volume ratio of 1:1 to obtain a 0.50 mol/L FeSO4 solution for later use;

c. respectively taking 1.00 mol/L FeCl3 solution and 0.50 mol/L FeSO4 solution with the same volume to be uniformly mixed in a beaker, and simultaneously heating the mixture by using a water bath and keeping the temperature at 30 ℃ to obtain mixed solution;

d. slowly dripping 1.00 mol/L NaOH solution into the mixed solution under the condition of stirring, then dripping concentrated ammonia water until the solution is completely blackened, and continuing dripping a small amount of sodium hydroxide solution when the solution is completely blackened, stirring and preserving heat for 2 hours at 30 ℃;

e. after stirring and incubation, the reaction mixture was centrifuged. Washing the black solid obtained by separation with absolute ethyl alcohol for 3 times, then washing with deionized water for 3 times, carrying out magnetic separation, and then carrying out vacuum drying at 80 ℃ to obtain Fe3O4 nano-particles for later use;

f. dispersing the obtained Fe3O4 nano particles in absolute ethyl alcohol, carrying out ultrasonic oscillation to uniformly disperse the particles, and then sequentially adding the absolute ethyl alcohol, deionized water and concentrated ammonia water to obtain a suspension;

g. stirring the suspension at 80 ℃ for 0.5h, slowly dropwise adding 0.5g of tetraethoxysilane, stirring at 80 ℃ for reflux reaction for 2h, centrifuging the reacted solution to obtain a solid product, and washing with deionized water for three times to obtain a magnetic SiO2 core;

h. dispersing magnetic SiO2 nuclei in absolute ethyl alcohol, performing ultrasonic oscillation to uniformly disperse particles, and sequentially adding deionized water, cetyl trimethyl ammonium bromide and concentrated ammonia water to obtain a SiO2 suspension;

i. stirring the SiO2 suspension at 80 ℃, slowly dropwise adding ethyl orthosilicate, stirring at 80 ℃, and carrying out reflux reaction to obtain a solid product;

j. and refluxing the solid product in a mixed solution of absolute ethyl alcohol and concentrated hydrochloric acid at 90 ℃ for 48h to remove a template agent of hexadecyl trimethyl ammonium bromide, repeating the process for more than two times until an absorption peak of CTAB in an infrared spectrum disappears, respectively washing the solid product with the absolute ethyl alcohol and deionized water for 3 times, carrying out magnetic separation, and carrying out vacuum drying at 80 ℃ to obtain the magnetic mesoporous silica.

Preferably, in the step d, the addition amount of the NaOH solution is the volume sum of 1.00 mol/L FeCl3 solution and 0.50 mol/L FeSO 4.

Compared with the prior art, the invention has the advantages and positive effects that,

the invention provides a method for synthesizing magnetic mesoporous silica for removing copper ions in water, which comprises the steps of synthesizing Fe3O4 nano particles by using ionic liquid, then taking Fe3O4 nano particles as seeds, slowly dripping TEOS under a heating condition to form nuclei, then taking CTAB as a template agent to synthesize Fe3O4@ SiO2, and finally removing the template agent to obtain the mesoporous silica taking Fe3O4 as magnetic nuclei. The necessity of synthesizing Fe3O4@ SiO2 core is proved by experiments. And finally, removing trace copper ions in the water body by using mesoporous Fe3O4@ SiO2 with a core-shell structure. The result shows that a large number of mesoporous structures exist on the surface and inside of the magnetic mesoporous silica, and the magnetic mesoporous silica has stronger adsorption capacity to copper ions when the pH value is 6 and the temperature is 60 ℃; the adsorption time is about 7h, and the adsorption capacity of the magnetic mesoporous silica to copper ions is saturated.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive labor.

FIG. 1 is a Scanning Electron Microscope (SEM) image of Fe3O4@ SiO2 nanoparticles provided in example 1, wherein B is an enlarged view of A, and the lower right corner of B is a Transmission Electron Microscope (TEM) image of a single particle;

FIG. 2 is a wide angle X-ray diffraction (WAXRD) of Fe3O4 and Fe3O4@ SiO2 nanoparticles;

FIG. 3 is a graph showing absorbance A-standard copper ion concentration c (mg/L);

FIG. 4 is a graph showing the influence of pH on the adsorption effect of magnetic mesoporous silica;

FIG. 5 is a graph showing the effect of the initial concentration of copper sulfate solution on the adsorption effect of magnetic mesoporous silica;

FIG. 6 is a graph showing the effect of temperature on the adsorption effect of magnetic mesoporous silica;

FIG. 7 is a graph showing the effect of adsorption time on the adsorption effect of magnetic mesoporous silica.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, the present invention will be further described with reference to the accompanying drawings and examples. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and thus the present invention is not limited to the specific embodiments of the present disclosure.

Raw materials: ferric chloride hexahydrate (FeCl 3.6H2O, national drug group, analytically pure); ferrous sulfate heptahydrate (FeSO4 & 7H2O, Wako pure chemical industries, Tianjin); 1-butyl-3-methylimidazolium tetrafluoroborate ([ Bmim ] BF4, Shanghai Aladdin Biotechnology Co., Ltd., > 97.0%); ammonia (NH 3. H2O, ddc chemical ltd, analytically pure); tetraethoxysilane (TEOS, tianjin maotai reagent factory, analytical purity); cetyl trimethylammonium bromide (CTAB, tianjinke meoh, chromatographically pure); sodium hydroxide (NaOH, science of west longu, analytically pure); absolute ethanol (C2H5OH, tianjin yu fine chemical plant, analytically pure); copper sulfate (CuSO4, Daojingsi scientific reagent factory, Tianjin, analytically pure); sulfuric acid (H2SO4, Fuyu fine chemical industry, Tianjin, analytically pure); acetone (analytical pure, Kangde chemical Co., Ltd., Laiyang city); sodium diethyldithiocarbamate (DDTC-Na, Sedrin Seiko, analytical pure).

Example 1, this example provides a method for synthesizing magnetic mesoporous silica for removing copper ions in water

Firstly, 13.5145g of FeCl3 & 6H2O are accurately weighed in a beaker, dissolved by a mixed solution of [ Bmim ] BF4 and H2O with the volume ratio of 1:1, and the volume is determined to be 50m L, so that 1.00 mol/L FeCl3 solution is obtained for standby.

0.50 mol/L FeSO4 solution, namely accurately weighing 6.9505g of FeSO4 & 7H2O in a beaker, dissolving the solution by using a mixed solution of [ Bmim ] BF4 and H2O in a volume ratio of 1:1, and fixing the volume to 50m L to obtain 0.50 mol/L FeSO4 solution for later use.

Respectively taking 1.00 mol/L FeCl3 solution of 25m L and 0.50 mol/L FeSO4 solution to be uniformly mixed in a beaker, simultaneously heating by water bath and preserving heat at 30 ℃, slowly dripping 1.00 mol/L NaOH solution to 50m L under the stirring condition, then dripping concentrated ammonia water to 10m L until the solution is completely blackened, measuring the pH to about 10.0 until the solution is completely blackened, when preparing Fe3O4 nano particles by adopting a coprecipitation method, firstly dripping 1.00 mol/L NaOH solution and then adding concentrated ammonia water, and in the experiment, if the pH is directly regulated by ammonia water to be concentrated 865, the turbid liquid color is not pure black in the reaction process, brownish red appears in the middle, and the product is not pure black, when the product is subjected to magnetic analysis, finding that the product directly regulating the pH by concentrated ammonia water to be prepared, a part of the substance has no magnetism, analyzing that Fe2O 4 with brownish red is mixed in the product, and when the product is subjected to magnetic analysis, when a small amount of Fe2O is mixed in the product, firstly dripping the concentrated ammonia water is added, and the pH is stirred for 4, and then the nano particles are continuously stirred, and the method is further added under the 3.

After the reaction was completed, the reaction mixture was centrifuged. Washing the black solid obtained by separation with absolute ethyl alcohol for 3 times, then washing with deionized water for 3 times, and carrying out magnetic separation and vacuum drying at 80 ℃ to obtain the Fe3O4 nano-particles.

Taking 0.5g of Fe3O4 nano-particles prepared in the last step, dispersing the nano-particles in 100m L absolute ethyl alcohol, carrying out ultrasonic oscillation to uniformly disperse the particles, sequentially adding 100m L absolute ethyl alcohol, 50m L deionized water and 2.5m L concentrated ammonia water, wherein the pH of the solution is about 9.0, stirring the suspension at 80 ℃ for 0.5h, slowly dropwise adding 0.5g of TEOS, stirring at 80 ℃ for reflux reaction for 2h, centrifuging the reacted solution to obtain a solid product, and washing with deionized water for three times to obtain the magnetic SiO2 core.

Dispersing magnetic SiO2 core in 150m L absolute ethyl alcohol, performing ultrasonic treatment for 0.5h, sequentially adding 100m L deionized water, 0.97g CTAB and 2.5m L concentrated ammonia water, wherein the pH value of the solution is about 9.0, stirring the suspension for 0.5h at 80 ℃, slowly dropwise adding 2.0g TEOS, stirring and refluxing for 2h at 80 ℃, refluxing the solid product in a mixed solution of 200m L absolute ethyl alcohol and 10m L concentrated hydrochloric acid for 48h at 90 ℃ to remove a template agent CTAB, repeating the process for more than two times until the absorption peak of CTAB in the infrared spectrum disappears, respectively washing the solid product for 3 times by using the absolute ethyl alcohol and the deionized water, performing magnetic separation, and performing vacuum drying at 80 ℃ to obtain the magnetic mesoporous silicon dioxide (Fe3O4@ SiO 2).

In this step, magnetic SiO2 core was synthesized and then magnetic mesoporous silica was prepared, mainly because it was found through experiments that if this step is omitted, then the color of the solution changed from brown black to bright yellow and the solid recovered after the reaction changed to white when the template agent CTAB was removed by refluxing a mixture of absolute ethanol and concentrated hydrochloric acid. The CTAB template is directly contacted with innermost Fe3O4, and when the template agent CTAB is removed by hydrochloric acid, Fe3O4 is dissolved after the CTAB is dissolved by hydrochloric acid, therefore, SiO2 core is synthesized first, and the internal Fe3O4 is protected.

Experimental analysis:

as seen in FIG. 1, the inner dark layer is an Fe3O4 core, and the outer light layer is an SiO2 shell. The outer silicon shell is formed by hydrolyzing Tetraethoxysilane (TEOS) in an alkaline environment, and the magnetic Fe3O4 nano particles can effectively prevent the agglomeration of the nano particles after being coated with SiO2, so that the magnetic Fe3O4 nano particles have better dispersibility. It can also be seen that the diameter of the Fe3O4@ SiO2 nanoparticles is approximately 300 nm.

As seen from FIG. 2, the nano-particles of the tubes Fe3O4 and Fe3O4@ SiO2 have different diffraction intensity values, but the diffraction peaks are almost the same, the 2 theta degree is similar to the literature value of the standard nano-Fe 3O4, and obvious characteristic diffraction peaks such as (220), (311), (400), (422), (551), (440) and the like appear. This result confirms that magnetic core Fe3O4 has been successfully synthesized and is intact after silica-encapsulated, mesoporous SiO2 growth. The phase of the prepared magnetic nano particle is of an inverse spinel structure, the peak shape is sharp, and the nano particle is completely crystallized.

The drawing of the standard curve is to perform an experiment of adsorbing copper ions in the water body by the magnetic mesoporous silica at the later stage and determine important contents of the residual copper ions in the water body after adsorption, so that the standard curve with a linear correlation coefficient of more than 0.9990 needs to be drawn, otherwise, the concentration of the copper ions in the water body after adsorption finally determined is caused to have a large error. The absorbance values of the copper ion solutions of different concentrations are shown in table 1.

TABLE 1 Absorbance of copper ion solutions of different concentrations

As can be seen from fig. 3, as the concentration of copper ions in the solution increases, the value of absorbance also increases, and the concentration of copper ions in the solution has a good linear correlation with the experimentally measured absorbance a, which conforms to the lambert beer law, and the linear regression equation of the standard curve is that y is 0.0472+0.181x, and the correlation coefficient is 0.9993.

In order to research the influence of the pH value of the solution on the removal of copper ions, the pH value range is 4.0-8.0, the copper ion solution l0m L with the initial concentration of 150 mg/L is accurately measured in a 30m L conical flask at room temperature, 50 mu g of magnetic mesoporous silica is then weighed in the conical flask, the conical flask is then placed on a constant-temperature magnetic stirrer to be stirred for 2h, and after centrifugation, the supernatant is taken to be tested by an ultraviolet visible spectrophotometer.

The absorbance values of the copper ion solution at different pH values are shown in Table 2.

TABLE 2 absorbance values of solutions of copper ions at different pH values

And substituting the measured absorbance into a copper ion standard curve y which is 0.0472+0.181x to obtain the copper ions in the solution, calculating the copper ion removal efficiency, and calculating the qt value according to an adsorption calculation formula. The concentration, removal efficiency and adsorption amount of copper ions after the reaction when the pH values of the solutions are different are shown in 3, and a graph 4 can be drawn according to data in a table.

TABLE 3 copper ion concentration, removal rate and adsorption capacity of the solutions at different pH values

As can be seen from the experimental data of fig. 4, the maximum adsorption rate of copper ions to the magnetic mesoporous silica is around pH 6.0.

In order to study the influence of the initial copper ion concentration on the copper ion adsorption effect, the experiment selects the pH value of 6.0 at which the adsorption efficiency of the magnetic mesoporous silica on the copper ions is the maximum.

Under the condition of room temperature, copper sulfate solutions 10m L with initial concentrations of 20 mg/L, 40 mg/L, 60 mg/L, 80 mg/L and 100 mg/L are accurately measured in 50m L erlenmeyer flasks respectively, then 50mg of magnetic mesoporous silica is weighed in the erlenmeyer flasks, the erlenmeyer flasks are placed on a constant-temperature magnetic stirrer to be stirred for 2 hours, after centrifugation, the supernate is taken to be tested by an ultraviolet visible spectrophotometer, and the data are listed in table 4.

TABLE 4 absorbance values of solutions at different initial concentrations

Substituting the measured absorbance into a copper ion standard curve y of 0.0472+0.181x to obtain copper ions in the solution, calculating the copper ion removal efficiency, calculating qt according to an adsorption calculation formula, wherein the copper ion concentration, removal efficiency and adsorption under different temperature conditions are shown in table 5, and the data in the table is shown in fig. 5.

TABLE 5 copper ion concentration and removal rate after adsorption of copper ion solutions of different initial concentrations

As can be seen from FIG. 5, the adsorption amount of the magnetic mesoporous silica increases with the initial concentration of copper ions, and the adsorption amount of the magnetic mesoporous silica to copper ions reaches a peak value at an initial concentration of 60 mg/L of the copper ion solution, which corresponds to a maximum adsorption amount of 16.82 mg/g.

In order to better study the influence of the solution temperature on the copper ion adsorption effect, the pH value of the magnetic mesoporous silica on the copper ion adsorption rate is 6.0, 50m L150 mg/L copper ion solution 50m L is accurately measured in five conical flasks, 50mg of magnetic mesoporous silica is then weighed and placed in each conical flask, stirring is continuously carried out at 30 ℃, 40 ℃, 50 ℃, 60 ℃ and 70 ℃ respectively under the condition of the same stirring speed, supernatant is taken after 2 hours, and the diluted sample is used for measuring the copper ion concentration in the solution by a spectrophotometry method.

TABLE 6 absorbance values of solutions of copper ions at different temperatures

And substituting the measured absorbance into a copper ion standard curve y of 0.0472+0.181x to obtain copper ions in the solution, calculating the removal efficiency of the copper ions, calculating a qt value according to an adsorption calculation formula, wherein the concentration, the removal efficiency and the adsorption of the copper ions under different temperature conditions are shown in table 7, and a graph 6 can be drawn according to the data in the table.

TABLE 7 copper ion concentration, removal efficiency and adsorption capacity under different reaction temperature conditions

The influence of the reaction temperature on the adsorption property of the magnetic mesoporous silica can be seen from the above table and fig. 6. In the process that the temperature is increased from 30 ℃ to 40 ℃, the removal efficiency is increased along with the increase of the reaction temperature as can be seen from the curve in the figure, but the increasing speed is relatively slow, but when the temperature is increased from 40 ℃ to 60 ℃, the removal rate is obviously increased along with the increase of the temperature as can be seen from the image, so that the removal rate is greatly influenced by the temperature in the temperature range, and analysis shows that the removal rate is increased due to the fact that copper ions have a higher moving rate at a higher temperature, the contact area of the magnetic mesoporous silica and the copper ions is increased, the removal rate of the magnetic mesoporous silica to the copper ions is increased, and when the temperature reaches 60 ℃, the removal efficiency reaches the maximum value, and the removal efficiency begins to decrease after the temperature reaches 60 ℃. In general, the removal efficiency of the magnetic mesoporous silica to copper ions increases with increasing temperature.

In order to study the influence of the adsorption time on the adsorption effect of heavy metal ions, the pH value was selected to be 6.0 and the solution temperature was set to be normal temperature in the experiment.

Accurately measuring a copper ion solution with the initial concentration of 150 mg/L to be 10m L in a 25m L conical flask, then weighing 50mg of magnetic mesoporous silica in the conical flask, then placing the conical flask on a constant-temperature magnetic stirrer, and testing the sample by using an ultraviolet spectrophotometer when the time range is 0-8 h.

TABLE 8 absorbance values of copper ion solutions at different adsorption times for the solutions

The measured absorbance is substituted into a standard curve y of copper ions, which is 0.0472+0.181x, to obtain the copper ions in the solution, the copper ion removal efficiency can be obtained by calculation, the copper ion concentration and removal efficiency under different reaction times are shown in table 9, and fig. 7 can be drawn according to the data in the table.

TABLE 9 copper ion concentration, removal rate and adsorption amount of the solution under different adsorption time conditions

The influence of the adsorption time on the copper ion adsorption effect is shown in fig. 7, the adsorption is fast in the initial stage, the adsorption rate is reduced in the later stage along with the lapse of time, the increase of the adsorption amount is slowed, and the adsorption effect tends to be balanced when the time reaches 7-8 h. The analysis reason is mainly because the surface of the magnetic mesoporous silica has a large number of adsorption sites at the initial stage of the adsorption process, and the adsorption reaction is easy to carry out, so that the adsorption reaction is fast. As adsorption continues, the adsorption sites on the surface of the nanomaterial become less and less available and gradually become occupied, and adsorption becomes relatively difficult.

And (4) conclusion:

accurately measuring 10m L150 mg/L copper ion solution 50m L in three conical flasks, then adjusting the pH value of the solution to 6.0, continuously stirring at 60 ℃, taking supernatant after 2h, measuring the absorbance A of the diluted sample by a spectrophotometry method to be 0.064, obtaining the copper ion concentration in the solution by substituting the copper ion concentration in the solution into a copper ion standard curve y of 0.0472+0.181x, obtaining the copper ion removal efficiency by calculation, calculating the qe value according to an adsorption amount calculation formula, and obtaining the copper ion concentration, the removal rate and the adsorption amount under the conditions of optimal temperature, pH and initial copper ion concentration in table 10.

TABLE 10 copper ion concentration, removal efficiency and adsorption amount under the optimum adsorption conditions

The invention through improvements

The method synthesizes Fe3O4@ SiO 2. Dissolving ferric trichloride and ferrous sulfate by using 1-butyl-3-methylimidazole tetrafluoroborate, synthesizing Fe3O4 nano particles by a coprecipitation method, taking Fe3O4 nano particles as seeds, slowly dripping TEOS under a heating condition to form nuclei, then synthesizing Fe3O4@ SiO2 by taking CTAB as a template agent, and finally removing the template agent to obtain the mesoporous silica taking Fe3O4 as magnetic nuclei. And removing trace copper ions in the water body by using mesoporous Fe3O4@ SiO2 with a core-shell structure. The result shows that a large number of mesoporous structures exist on the surface and inside of the magnetic mesoporous silica, and the magnetic mesoporous silica has stronger adsorption capacity to copper ions when the pH value is 6 and the temperature is 60 ℃; the adsorption time is about 7h, and the adsorption capacity of the magnetic mesoporous silica to copper ions is saturated.

The above description is only a preferred embodiment of the present invention, and not intended to limit the present invention in other forms, and any person skilled in the art may apply the above modifications or changes to the equivalent embodiments with equivalent changes, without departing from the technical spirit of the present invention, and any simple modification, equivalent change and change made to the above embodiments according to the technical spirit of the present invention still belong to the protection scope of the technical spirit of the present invention.

Claims (2)

1. A synthetic method of magnetic mesoporous silica for removing copper ions in water is characterized by comprising the following steps:

a. firstly, accurately weighing FeCl3 & 6H2O in a beaker, and dissolving the FeCl3 & 6H2O in a mixed solution of 1-butyl-3-methylimidazole tetrafluoroborate and H2O in a volume ratio of 1:1 to obtain a 1.00 mol/L FeCl3 solution for later use;

b. accurately weighing FeSO4 & 7H2O in a beaker, and dissolving the FeSO4 & 7H2O in a mixed solution of 1-butyl-3-methylimidazolium tetrafluoroborate and H2O in a volume ratio of 1:1 to obtain a 0.50 mol/L FeSO4 solution for later use;

c. respectively taking 1.00 mol/L FeCl3 solution and 0.50 mol/L FeSO4 solution with the same volume to be uniformly mixed in a beaker, and simultaneously heating the mixture by using a water bath and keeping the temperature at 30 ℃ to obtain mixed solution;

d. slowly dripping 1.00 mol/L NaOH solution into the mixed solution under the condition of stirring, then dripping concentrated ammonia water until the solution is completely blackened, and continuing dripping a small amount of sodium hydroxide solution when the solution is completely blackened, stirring and preserving heat for 2 hours at 30 ℃;

e. after stirring and incubation, the reaction mixture was centrifuged. Washing the black solid obtained by separation with absolute ethyl alcohol for 3 times, then washing with deionized water for 3 times, carrying out magnetic separation, and then carrying out vacuum drying at 80 ℃ to obtain Fe3O4 nano-particles for later use;

f. dispersing the obtained Fe3O4 nano particles in absolute ethyl alcohol, carrying out ultrasonic oscillation to uniformly disperse the particles, and then sequentially adding the absolute ethyl alcohol, deionized water and concentrated ammonia water to obtain a suspension;

g. stirring the suspension at 80 ℃ for 0.5h, slowly dropwise adding 0.5g of tetraethoxysilane, stirring at 80 ℃ for reflux reaction for 2h, centrifuging the reacted solution to obtain a solid product, and washing with deionized water for three times to obtain a magnetic SiO2 core;

h. dispersing magnetic SiO2 nuclei in absolute ethyl alcohol, performing ultrasonic oscillation to uniformly disperse particles, and sequentially adding deionized water, cetyl trimethyl ammonium bromide and concentrated ammonia water to obtain a SiO2 suspension;

i. stirring the SiO2 suspension at 80 ℃, slowly dropwise adding ethyl orthosilicate, stirring at 80 ℃, and carrying out reflux reaction to obtain a solid product;

j. and refluxing the solid product in a mixed solution of absolute ethyl alcohol and concentrated hydrochloric acid at 90 ℃ for 48h to remove a template agent of hexadecyl trimethyl ammonium bromide, repeating the process for more than two times until an absorption peak of CTAB in an infrared spectrum disappears, respectively washing the solid product with the absolute ethyl alcohol and deionized water for 3 times, carrying out magnetic separation, and carrying out vacuum drying at 80 ℃ to obtain the magnetic mesoporous silica.

2. The method as claimed in claim 1, wherein the NaOH solution is added in an amount of 1.00 mol/L FeCl3 solution and 0.50 mol/L FeSO4 in the d step.

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