CN111939909A

CN111939909A - Iron-based hollow silicon ball catalyst and preparation method and application thereof

Info

Publication number: CN111939909A
Application number: CN201910412041.4A
Authority: CN
Inventors: 陈越; 赵文丽; 吉庆敏
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2019-05-17
Filing date: 2019-05-17
Publication date: 2020-11-17

Abstract

The invention discloses an iron-based hollow silicon sphere catalyst, and a preparation method and application thereof. The catalyst is prepared by taking a solid nano silicon dioxide ball as a template and loading an iron component on a hollow silicon dioxide microsphere by a one-pot method. The iron-based hollow silicon sphere catalyst has the advantages of large specific surface area, uniform dispersion of catalytic active sites and the like, iron is loaded on the hollow spheres, the loss of an iron component is effectively prevented, the iron-based hollow silicon sphere catalyst can efficiently degrade dyes and has better stability in the heterogeneous Fenton reaction process of degradation of acid orange seven dyes in printing and dyeing wastewater, the separation from the wastewater is easy to realize and the reuse of the dye, and the iron-based hollow silicon sphere catalyst has application prospects in the field of wastewater and sewage treatment.

Description

Iron-based hollow silicon ball catalyst and preparation method and application thereof

Technical Field

The invention relates to an iron-based hollow silicon sphere catalyst, a preparation method and application thereof, and belongs to the technical field of organic dye degradation catalysts.

Background

Iron has wide sources, low price and good catalytic performance, is paid much attention to the field of non-noble metal catalysts, and is widely applied to catalytic reaction processes such as Fischer-Tropsch reaction, ammonia industrial production and the like. The mesoporous material has the advantages of special porous structure, uniform pore size distribution, large specific surface area, strong adsorbability and the like, and has good application prospect in wastewater and sewage treatment. The nano iron particles with catalytic performance are compounded on the mesoporous material, and the mesoporous material is functionally improved, so that the mesoporous material has high catalytic performance, is applied to high-efficiency degradation of dyes, and is a research hotspot in the current dye degradation.

Among a plurality of dye degradation technologies, the Fenton oxidation method is a green treatment technology which is efficient, stable, simple, convenient and environment-friendly. The process is carried out with H₂O₂Mainly of Fe²⁺Catalysis H₂O₂Hydroxyl free radical (. OH) with strong oxidation capacity is generated, the oxidation potential is as high as +2.8V, and the oxidative degradation of most organic matters can be realized.

Chinese patent application 201410166243.2 loads ferrous component on MIL-100(Fe) substrate by hydrothermal method to obtain load type Fe-based metal organic framework heterogeneous Fenton catalyst Fe^∥@ MIL-100 (Fe). The catalyst is applied to Fenton reaction for degrading dye, and the removal rate is 91% when the reaction time is 285min, so that the dye degradation efficiency is low. Chinese patent application 201310439830.X adopts a chemical oxidative polymerization method to prepare polyphenol, then grafts the polyphenol onto graphene through an ultrasonic chemical method, and finally adopts an ultrasonic-assisted coprecipitation method to prepare the hydroquinone/graphene/Fe₃O₄The Fenton-like catalyst has a complex preparation process and is not suitable for large-scale application.

Disclosure of Invention

Aiming at the problems of low reaction efficiency, complex operation, difficult recycling of the catalyst caused by dissolution of an iron component and the like of the existing iron-based Fenton catalyst, the invention provides the iron-based hollow silicon ball catalyst which is simple in method, high in efficiency, stable and reusable, and the preparation method thereof.

The technical scheme of the invention is as follows:

the preparation method of the iron-based hollow silicon ball catalyst comprises the steps of taking a solid nano silicon dioxide ball as a template, and loading an iron component on the hollow silicon ball by a one-pot method to obtain Fe-SiO₂Namely the iron-based hollow silicon ball catalyst, the specific steps are as follows:

uniformly mixing silicon dioxide microspheres, water, anhydrous ferric trichloride and sodium borohydride according to the mass ratio of 0.27-1.6: 1 of ferric trichloride to silicon dioxide, placing the mixture in a reaction kettle, carrying out hydrothermal reaction at 70-110 ℃, and after the reaction is finished, carrying out centrifugal separation to obtain the iron-based hollow silicon sphere catalyst.

Preferably, the mass ratio of water to silica is 16.7: 1.

Preferably, the hydrothermal reaction temperature is 80 ℃.

Preferably, the hydrothermal reaction time is 3-12 h.

The invention also provides the iron-based hollow silicon sphere catalyst prepared by the preparation method.

Further, the invention provides an application of the iron-based hollow silicon sphere-containing catalyst in catalytic degradation of dye, and the specific method comprises the following steps: adding an iron-based hollow silicon ball catalyst and hydrogen peroxide into the dye solution, adjusting the pH to 3-5, and stirring until the degradation is complete.

Preferably, the dye is acid orange seven.

Preferably, the addition amount of the iron-based hollow silica sphere catalyst is 0.4 g/L.

Preferably, the adding amount of the hydrogen peroxide is 0.6 mol/L.

Preferably, the pH is 4.

Compared with the prior art, the invention has the following advantages:

(1) the iron-based hollow silicon ball catalyst prepared by the one-pot method has large specific surface area of 571.9649g/m²；

(2) The catalytic active sites of the catalyst are uniformly dispersed, and the circulation between ferrous iron and ferric iron in the matrix can effectively catalyze and decompose H₂O₂Hydroxyl free radicals are generated, so that the dye molecules can be rapidly, efficiently and thoroughly degraded, and when the reaction time is 3min, the degradation efficiency is as high as 100 percent, and the catalytic efficiency is very high;

(3) the iron is loaded on the hollow ball, so that the loss of iron components is effectively prevented, the stability of the catalyst is improved, secondary pollution is avoided, the iron ions are fixed on the solid-phase silicon dioxide, the separation of the catalyst and waste water is favorably realized, the circulating stability is better, and the industrialized use is favorably realized.

Drawings

FIG. 1 is an elemental Mapping picture of an iron-based hollow silica sphere catalyst prepared in example 1;

FIG. 2 is a graph comparing the removal of the dye acid orange seven by the Fenton system containing the iron-based hollow silica sphere catalyst prepared in example 1 and no catalyst;

FIG. 3 is a graph comparing the removal of dye acid orange seven by iron-based catalysts of varying iron content prepared in example 2;

FIG. 4 is a graph comparing the removal of dye acid orange seven by the iron-based catalyst prepared in example 3 under different pH reaction conditions;

FIG. 5 shows the iron-based catalyst prepared in example 4 in different H₂O₂A comparison graph of the removal effect of dye acid orange seven under the dosage;

fig. 6 is a graph comparing the removal of acid orange heptanes in the same Fenton reaction system with different amounts of iron-based catalyst in example 5.

Detailed Description

The invention is described in further detail below with reference to the figures and specific examples.

The preparation method of the hollow silicon ball containing the iron base comprises the following specific steps:

(1) preparing the silicon dioxide microspheres: by using

Mixing 24.75mL of deionized water and 61.75mL of absolute ethyl alcohol, and magnetically stirring for 10 min; adding 9mL of ammonia water into the system, and continuing stirring for 20 min; then adding 4.5mL of TEOS and stirring for 2 h; and centrifuging the reacted liquid to obtain the silicon dioxide microspheres, and cleaning the silicon dioxide microspheres for 4-5 times by using alcohol.

(2)Fe-SiO₂Preparation of the catalyst: mixing 10-1000 mg of silicon dioxide microspheres with 5ml of deionized water, 0.5-3 mmol of anhydrous ferric trichloride (iron source) and 500-3000 mg of sodium borohydride uniformly, placing the mixture in a reaction kettle, and adding the mixture into the reaction kettlePreserving heat for 3-12 h at 70-110 ℃; centrifuging to obtain yellow green colloidal solid, namely the iron-based hollow silicon spheres, and washing the yellow green colloidal solid to be neutral by using deionized water; finally, the solid was freeze-dried.

Example 1

Uniformly mixing 300mg of silicon dioxide microspheres, 5ml of deionized water, anhydrous ferric trichloride with different masses (the mass ratio of ferric trichloride to silicon dioxide microspheres is respectively 0.27:1, 0.53:1, 1.07:1 and 1.6:1, which respectively correspond to the iron content of 0.5, 1, 2 and 3mmol) and 500mg of sodium borohydride, placing the mixture in a reaction kettle, and preserving the heat for 12 hours at 80 ℃; centrifuging to obtain yellow green colloidal solid, namely the iron-based hollow silicon spheres, and washing the yellow green colloidal solid to be neutral by using deionized water; finally, the solid is frozen and dried to obtain Fe-SiO with different iron contents₂The catalyst is used for catalyzing and degrading dye acid orange seven (AO7) through Fenton reaction, and the catalyst is respectively marked as Fe-SiO₂-0.5mmol、Fe-SiO₂-1mmol、Fe-SiO₂-2mmol and Fe-SiO₂-3mmol。

Degradation experimental procedure for AO7 was as follows: adding Fe-SiO into AO7 solution with the concentration of 100mg/L₂Adjusting the pH value of the catalyst and hydrogen peroxide to 4 by hydrochloric acid, and stirring at room temperature for 5-10min at the rotating speed of 250 rpm. Wherein, Fe-SiO₂The addition amount of the catalyst is 0.6g/L, and the addition amount of the hydrogen peroxide is 0.2 mol/L. Sampling at intervals, separating the catalyst from the solution by using a filter head, and quantitatively analyzing the residual amount of AO7 in the degradation process by using an ultraviolet-visible spectrophotometer after the filtered solution is taken. The characteristic absorption wavelength of AO7 was 484.5 nm.

Fig. 1 is an elemental Mapping picture of the prepared iron-based hollow silica sphere catalyst, and it can be seen from the figure that the iron-based hollow silica sphere catalyst is composed of Fe, O and Si.

The test result of the degradation experiment of the prepared iron-based hollow silicon sphere catalyst on AO7 when the mass ratio of ferric trichloride to silicon dioxide microspheres is 0.27:1 is shown in figure 2, and after 5min of reaction, the removal efficiency of AO7 reaches 100%, and the catalytic degradation efficiency is very high. After the reaction is finished, the residual solution is centrifuged, the catalyst is separated out and reused, and the removal efficiency of the catalyst to AO7 3 rd time is still up to 100% within 30min of reaction time, which indicates that the catalyst of the invention has better circulation stability.

The degradation experiment test effect of the hollow silicon ball catalyst containing iron base prepared by different mass ratios of ferric trichloride and silicon dioxide microspheres on AO7 is shown in figure 3, and the comparison of the experiment results shows that when the mass ratio of ferric trichloride and silicon dioxide is 0.27:1 (the iron content is 0.5mmol, Fe-SiO is 0.5mmol)₂The catalytic effect is relatively best when the amount is-0.5 mmol), and the degradation efficiency reaches 100 percent when the reaction time reaches 10 min. When the mass ratio of ferric trichloride to silicon dioxide microspheres is higher than 0.27:1, the degradation efficiency of the obtained iron-based hollow silicon sphere catalyst for dye is slightly reduced.

Example 2

0.6g/L Fe-SiO was added to 100mg/L AO7 solution₂Adjusting the pH value of the solution to different values (3, 4, 5 and 7) by using hydrochloric acid, stirring for 30min in a shade at room temperature, wherein the rotating speed is 250rpm, and the catalyst is 0.5mmol and 0.2mol/L hydrogen peroxide. As shown in fig. 4, the catalytic degradation effect of the iron-based hollow silica sphere catalyst is the best when the pH is 4, and AO7 is completely degraded already at the reaction time of 5 min. When the pH is less than 4 or more than 4, the degradation effect is reduced.

Example 3

0.6g/L Fe-SiO was added to 100mg/L AO7 solution₂0.5mmol of catalyst, adjusting the pH of the solution to 3, and adding 0.2mol/L, 0.4mol/L and 0.6mol/L of H respectively₂O₂Stirring in a dark place at room temperature for 30min at the rotating speed of 250rpm, and investigating the influence of the hydrogen peroxide dosage on the dye removal effect. The degradation effect is shown in FIG. 5 when H₂O₂The catalyst is most effective in removing AO7 when the amount is 0.6 mol/L. At a reaction time of 5min, the dye had degraded completely. When H is present₂O₂When the amount is less than 0.6mol/L, the degradation efficiency is reduced.

Example 4

To 100mg/L AO7 solution was added 0.2mol/L H₂O₂Adjusting the pH value of the solution to 4, and adding 0.2g/L, 0.4g/L and 0.6g/L Fe-SiO₂0.5mmol of catalyst, investigation of the effectiveness of the removal by different amounts of catalystInfluence. As shown in FIG. 6, when the amount of the catalyst used was 0.4g/L, the degradation efficiency of the iron-based hollow silica sphere catalyst to AO7 was the highest, and after 3min of reaction, the degradation efficiency reached 100%.

Claims

1. The preparation method of the iron-based hollow silicon sphere catalyst is characterized by comprising the following specific steps of:

2. The method according to claim 1, wherein the mass ratio of water to silica is 16.7: 1.

3. The method according to claim 1, wherein the hydrothermal reaction temperature is 80 ℃.

4. The preparation method according to claim 1, wherein the hydrothermal reaction time is 3-12 h.

5. The iron-based hollow silica sphere catalyst produced by the production method according to any one of claims 1 to 4.

6. Use of the iron-based hollow silica sphere catalyst of claim 5 for catalytically degrading a dye.

7. The application of claim 6, wherein the specific method is as follows: adding an iron-based hollow silicon ball catalyst and hydrogen peroxide into the dye solution, adjusting the pH to 3-5, and stirring until the degradation is complete.

8. Use according to claim 7, wherein the dye is acid orange seven.

9. The application of claim 7, wherein the addition amount of the iron-based hollow silica sphere catalyst is 0.4g/L, and the addition amount of hydrogen peroxide is 0.6 mol/L.

10. Use according to claim 7, wherein the pH is 4.