CN112169727B - Preparation method of halloysite-based micro-nano reactor for advanced catalytic oxidation - Google Patents

Abstract

The invention relates to a preparation method of a halloysite-based micro-nano reactor for advanced catalytic oxidation, and belongs to the technical field of inorganic non-metallic materials. Specific steps: 1) Place the natural halloysite powder in a mixed acid solution, ultrasonically disperse for 5~8 hours, centrifuge, alternately wash with deionized water and absolute ethanol until the filtrate is neutral, and dry at 60 °C; 2) Step 1 ) The obtained product was placed in the modifier solution, stirred at 50~80 °C for 12~24 h, centrifuged, washed with deionized water until the filtrate became neutral, and dried at 60 °C; 3) The product obtained in step 2) was placed in deionized water In water, after ultrasonic dispersion for 10~30min, FeSO ₄ ·7H ₂ O was added, and ultrasonic dispersion was carried out for 10~30min. The obtained suspension was placed in a vacuum bottle for 1~3h, then ultrasonically dispersed, and then vacuumed and let stand. Repeat this for 3 to 5 times, then add mixed lye, crystallize at 80 to 95 °C for 2 to 5 hours, centrifuge, and dry; 4) Place the product obtained in step 3) in an organic pollutant solution, add an oxidant, and react All organic pollutants are degraded after a certain period of time.

Description

Preparation method of halloysite-based micro-nano reactor for advanced catalytic oxidation

technical field

The invention provides a preparation method for in-situ growth of nanometer Fe3O4 in natural halloysite nanotubes, and belongs to the technical field of inorganic non-metallic materials.

Background technique

The organic pollution of water bodies is getting worse day by day on a global scale, and the social and environmental problems caused by it have attracted great attention from governments around the world, and the demand for new and efficient organic pollutant purification technologies is even more urgent. Biorefractory organic polluted wastewater has many types, high toxicity and stable structure, and it is difficult to effectively treat it by traditional physical-chemical or biodegradation methods, so it has become a hot spot and difficulty in the environmental field. In recent years, advanced catalytic oxidation technology (advanced catalytic oxidation) has been widely used in the treatment of refractory organic polluted wastewater. Advanced catalytic oxidation technology uses transition metal ions as catalysts to catalyze hydrogen peroxide or persulfate to generate hydroxyl radicals or sulfuric acid radicals with high oxidation activity, which can oxidize and degrade stubborn organic pollutants in water that are difficult to deal with by other technologies in a non-selective manner. Although efficient, advanced catalytic oxidation technology has many shortcomings in practical applications: narrow reaction pH range, low utilization rate of hydrogen peroxide or persulfate, and difficulty in recovering transition metal ions, resulting in secondary pollution. To overcome these shortcomings, heterogeneous catalysts have received extensive attention, in which transition metal ions are immobilized in the structure of solid catalysts.

In recent years, advanced catalytic oxidation technologies using different iron (hydroxy) oxides as catalysts have been widely studied, such as Fe3O4, Fe2O3, α-FeOOH, β-FeOOH, etc. the highest activity. The octahedral site of the Fe3O4 structure can accommodate both divalent Fe(II) and trivalent Fe(III), and iron ions can be reversibly oxidized and reduced at this site without changing the crystal structure. In addition, Fe3O4 can also be recycled and reused by simple magnetic separation, and has low solubility in water and good catalytic stability, so it is considered as a promising heterogeneous catalyst. However, nano-Fe3O4 particles are easy to agglomerate in water, reducing the specific surface area and reactive sites, thereby reducing the reactivity. Immobilization is one of the strategies to solve the aggregation problem and improve the dispersibility.

Due to its special confinement effect and selection effect, micro-nano reactors exhibit excellent chemical reactivity, and have received widespread attention in the fields of chemistry, biology, medicine, and materials in recent years. At present, most of the micro-nano reactors are artificially synthesized, including core-shell structure, core-tube structure, yolk-egg-shell structure, etc. The commonly used materials are molecular sieves, mesoporous silica, mesoporous carbon materials, and layered silicic acid. Salt, carbon nanotubes, etc., which will undoubtedly increase the cost of the micro-nano reactor. Natural halloysite nanotubes (HNTs) also have a typical hollow tubular structure and are clay minerals with abundant resources, cheap and easy to obtain. Halloysite nanotubes have the advantages of high porosity, large specific surface area, adjustable surface chemical properties, and excellent thermal stability.

Nano Fe3O4 particles are grown in situ in natural halloysite nanotubes and used as a micro-nano reactor for advanced catalytic oxidation. Nano Fe3O4 catalyzes the reaction of hydrogen peroxide or persulfate, highly oxidative active free radicals and organic pollutants in halloysite nanotubes. The confinement effect and selection effect of the microenvironment in the tube are used to enhance the catalytic oxidation reaction activity and improve organic pollution. biodegradation efficiency. Moreover, my country is rich in halloysite resources and widely distributed, and is a country with large halloysite resources. The implementation of this patent has important theoretical significance for the development of advanced catalytic oxidation technology and the promotion of comprehensive crossover and organic integration of multiple disciplines. At the same time, it can increase the added value of the development and utilization of halloysite in my country, promote the structural adjustment of traditional industries, strengthen and deepen the application research and development of halloysite in the field of environmental protection, and give full play to my country's resource advantages and characteristics.

SUMMARY OF THE INVENTION

The invention utilizes the natural halloysite nanotube structure to realize the in _- situ growth of nanometer _Fe3O4 particles in the tube, and develops a preparation method of a high-efficiency micro-nano reactor for advanced catalytic oxidation technology.

The invention provides a preparation method of a halloysite-based micro-nano reactor for advanced catalytic oxidation. group grafting. Using the electrostatic adsorption between the grafted groups and ferrous ions, the ferrous ions are attached to the inner wall of the tube, and then through the control of experimental conditions, the in-situ growth of nano-Fe ₃ O ₄ particles in the tube is realized. Thus, a preparation method of a halloysite-based micro-nano reactor for advanced catalytic oxidation is obtained.

The preparation method of the halloysite-based micro-nano reactor for advanced catalytic oxidation provided by the present invention, its main technical scheme is as follows:

1) Acidification and purification of natural halloysite nanotubes: put natural halloysite powder in mixed acid solution, ultrasonically disperse for 5~8h, centrifuge, alternately wash with deionized water and absolute ethanol until the filtrate is neutral, and dry at 60°C For standby use, the mixed acid used is two kinds of concentrated sulfuric acid, concentrated phosphoric acid, concentrated hydrochloric acid and concentrated nitric acid;

2) Internal modification of halloysite nanotubes: place the purified halloysite in a modifier solution of a certain concentration, stir at 50-80 °C for 12-24 hours, centrifuge, and wash with deionized water until the filtrate is neutral. Dry at 60°C for later use, and the modifiers used are sulfamic acid, sodium dodecylbenzenesulfonate, oxalic acid, acetic acid, vinyl acetate, citric acid, sodium citrate, ethylenediaminetetraacetic acid, benzoic acid, peroxal Ammonium sulfate, toluene, xylene, propylmethyldimethoxysilane, N-aminoethyl-3-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-amino One or more combinations of propylmethyldimethoxysilane, methyl ethyl ketoxime, azobisisobutyronitrile, dibenzoyl peroxide, methyl methacrylate;

3) In situ growth in nano Fe ₃ O ₄ tubes: Put the modified halloysite nanotubes in deionized water, after ultrasonic dispersion for 10~30min, add FeSO ₄ ·7H ₂ O, and ultrasonically disperse for 10~30min, the obtained The suspension is placed in a vacuum bottle and left to stand for 1~3 hours, then ultrasonically dispersed, and then vacuumed and allowed to stand. Repeat this for 3~5 times. Then, add mixed lye, crystallize at 80~95°C for 2~5 hours, and centrifuge. separation and drying to obtain a halloysite-based micro-nano reactor for in-situ growth of nano-Fe ₃ O ₄ in the tube;

₄ ) Application of advanced catalytic oxidation: The halloysite nanotubes with in-situ growth of nano- _Fe3O4 in the tube are placed in a certain concentration of organic pollutant solution, and oxidant is added, and advanced catalytic oxidation is carried out in a halloysite-based micro-nano reactor. The organic pollutants are efficiently degraded.

In the above technical solution of the present invention, the mixed alkali solution used in step 3) is one or more of NaOH, KOH, Na ₂ CO ₃ , K ₂ CO ₃ , NaHCO ₃ , KHCO ₃ , NaNO ₃ , KNO ₃ combination.

In the above technical solution of the present invention, the oxidant used in step 4) is hydrogen peroxide or persulfate.

In the above technical solutions of the present invention, the purity of the chemical reagents used is not lower than analytical purity.

In the preparation method of the halloysite-based micro-nano reactor for advanced catalytic oxidation provided by the invention, the obtained Fe ₃ O ₄ particles have a size of 5-10 nm. The method provided by the invention is simple in operation, easy to control, low in synthesis temperature, low in energy consumption and low in preparation cost, and the reagents used are environmentally friendly, non-toxic and non-corrosive, and can realize mass production.

Description of drawings

Fig. 1 is the XRD pattern of the representative sample;

Figure 2 is a TEM photograph of a representative sample;

Figure 3 is an evaluation of catalytic oxidation performance of representative samples.

Detailed ways

Example 1

1) Place the natural halloysite powder in a mixed solution of concentrated sulfuric acid and concentrated phosphoric acid (volume ratio 1:1), ultrasonically disperse for 5-8 hours, centrifuge, and alternately wash with deionized water and absolute ethanol until the filtrate is neutral, 60 ℃ drying for use;

2) The product obtained in step 1) is placed in a mixed solution of sulfamic acid and ethylenediaminetetraacetic acid, stirred at 50~80°C for 12~24h, centrifuged, washed with deionized water until the filtrate is neutral, and dried at 60°C for later use ;

3) The product obtained in step 2) is placed in deionized water, and after ultrasonic dispersion for 10~30min, FeSO ₄ ·7H ₂ O is added, and ultrasonically dispersed for 10~30min, and the obtained suspension is placed in a vacuum bottle for 1~30 minutes. 3h, ultrasonically disperse again, then vacuum and stand, repeat this for 3~5 times, then, add _NaOH and _Na2CO3 mixed solution, crystallize at 80~95°C for 2~5h, centrifuge, and dry to obtain the product;

4) The product obtained in step 3) is placed in an organic pollutant solution, and hydrogen peroxide is added, and the organic pollutants are all degraded after a period of time.

Example 2

1) Place the natural halloysite powder in a mixed solution of concentrated sulfuric acid and concentrated hydrochloric acid (volume ratio 2:1), ultrasonically disperse for 5-8 hours, centrifuge, and alternately wash with deionized water and absolute ethanol until the filtrate is neutral, 60 ℃ drying for use;

2) The product obtained in step 1) was placed in N-aminoethyl-3-aminopropylmethyldimethoxysilane solution, stirred at 50-80 °C for 12-24 h, centrifuged, and washed with deionized water until the filtrate was Neutral, dry at 60℃ for later use;

3) Place the product obtained in step 2) in deionized water, and after ultrasonic dispersion for 10~30min, add FeSO ₄ ·7H ₂ O, and then ultrasonically disperse for 10~30min, the obtained suspension is placed in a vacuum bottle and vacuumized for 1~ 3h, ultrasonically disperse again, then vacuum and stand, repeat this 3~5 times, then add a mixed solution of NaOH and KHCO ₃ , crystallize at 80~95°C for 2~5h, centrifuge, and dry to obtain the product;

4) The product obtained in step 3) is placed in an organic pollutant solution, and persulfate is added, and the organic pollutants are all degraded after a period of time.

Example 3

1) Place the natural halloysite powder in a mixed solution of concentrated sulfuric acid and concentrated nitric acid (volume ratio 3:1), ultrasonically disperse for 5~8 hours, centrifuge, and alternately wash with deionized water and absolute ethanol until the filtrate is neutral, 60 ℃ drying for use;

2) The product obtained in step 1) was placed in an acetic acid solution, stirred at 50-80 °C for 12-24 h, centrifuged, washed with deionized water until the filtrate was neutral, and dried at 60 °C for use;

3) Place the product obtained in step 2) in deionized water, and after ultrasonic dispersion for 10~30min, add FeSO ₄ ·7H ₂ O, and then ultrasonically disperse for 10~30min, the obtained suspension is placed in a vacuum bottle and vacuumized for 1~ 3h, ultrasonically disperse again, then vacuum and stand, repeat this for 3~5 times, then add a mixed solution of NaOH and NaNO ₃ , crystallize at 80~95°C for 2~5h, centrifuge, and dry to obtain the product;

4) The product obtained in step 3) is placed in an organic pollutant solution, and hydrogen peroxide is added, and the organic pollutants are all degraded after a period of time.

Example 4

1) Place the natural halloysite powder in a mixed solution of concentrated phosphoric acid and concentrated nitric acid (volume ratio 4:1), ultrasonically disperse for 5~8 hours, centrifuge, and alternately wash with deionized water and absolute ethanol until the filtrate is neutral, 60 ℃ drying for use;

2) The product obtained in step 1) is placed in a citric acid solution, stirred at 50-80 °C for 12-24 h, centrifuged, washed with deionized water until the filtrate is neutral, and dried at 60 °C for use;

3) Place the product obtained in step 2) in deionized water, and after ultrasonic dispersion for 10~30min, add FeSO ₄ ·7H ₂ O, and then ultrasonically disperse for 10~30min, the obtained suspension is placed in a vacuum bottle and vacuumized for 1~ 3h, ultrasonically disperse again, then vacuum and stand, repeat this for ₃ ~5 times, then add a mixed solution of _NaHCO3 and NaNO3, crystallize at 80~95°C for 2~5h, centrifuge, and dry to obtain the product;

4) The product obtained in step 3) is placed in an organic pollutant solution, and persulfate is added, and the organic pollutants are all degraded after a period of time.

Example 5

1) Place the natural halloysite powder in a mixed solution of concentrated phosphoric acid and concentrated hydrochloric acid (volume ratio 5:1), ultrasonically disperse for 5-8 hours, centrifuge, and alternately wash with deionized water and absolute ethanol until the filtrate is neutral, 60 ℃ drying for use;

2) The product obtained in step 1) was placed in a mixed solution of azobisisobutyronitrile and dibenzoyl peroxide, stirred at 50-80 °C for 12-24 h, centrifuged, and washed with deionized water until the filtrate was neutral, 60 ℃ drying for use;

3) Place the product obtained in step 2) in deionized water, and after ultrasonic dispersion for 10~30min, add FeSO ₄ ·7H ₂ O, and then ultrasonically disperse for 10~30min, the obtained suspension is placed in a vacuum bottle and vacuumized for 1~ 3h, ultrasonically disperse again, then vacuum and stand, repeat this for 3~5 times, then add a mixed solution of NaOH and _NaHCO3 , crystallize at 80~95°C for 2~5h, centrifuge, and dry to obtain the product;

4) The product obtained in step 3) is placed in an organic pollutant solution, and hydrogen peroxide is added, and the organic pollutants are all degraded after a period of time.

Example 6

1) Place the natural halloysite powder in a mixed solution of concentrated nitric acid and concentrated hydrochloric acid (volume ratio 6:1), ultrasonically disperse for 5-8 hours, centrifuge, and alternately wash with deionized water and absolute ethanol until the filtrate is neutral, 60 ℃ drying for use;

2) The product obtained in step 1) was placed in a mixed solution of toluene and propylmethyldimethoxysilane, stirred at 50-80 °C for 12-24 h, centrifuged, washed with deionized water until the filtrate was neutral, and dried at 60 °C. dry spare;

3) Place the product obtained in step 2) in deionized water, and after ultrasonic dispersion for 10~30min, add FeSO ₄ ·7H ₂ O, and then ultrasonically disperse for 10~30min, the obtained suspension is placed in a vacuum bottle and vacuumized for 1~ 3h, ultrasonically disperse again, then vacuum and stand, repeat this for 3~5 times, then add a mixed solution of NaOH and KOH, crystallize at 80~95°C for 2~5h, centrifuge, and dry to obtain the product;

4) The product obtained in step 3) is placed in an organic pollutant solution, and persulfate is added, and the organic pollutants are all degraded after a period of time.

Example 7

1) Place the natural halloysite powder in a mixed solution of concentrated nitric acid and concentrated phosphoric acid (volume ratio 6:1), ultrasonically disperse for 5-8 hours, centrifuge, and alternately wash with deionized water and anhydrous ethanol until the filtrate is neutral, 60 ℃ drying for use;

2) The product obtained in step 1) is placed in a mixed solution of sodium citrate and benzoic acid, stirred at 50-80 °C for 12-24 h, centrifuged, washed with deionized water until the filtrate is neutral, and dried at 60 °C for use;

3) The product obtained in step 2) is placed in deionized water, and after ultrasonic dispersion for 10~30min, FeSO ₄ ·7H ₂ O is added, and ultrasonically dispersed for 10~30min, and the obtained suspension is placed in a vacuum bottle for 1~30 minutes. 3h, ultrasonically disperse again, then vacuum and stand, repeat this for 3~5 times, then add KOH and KHCO ₃ mixed solution, crystallize at 80~95°C for 2~5h, centrifuge, and dry to obtain the product;

4) The product obtained in step 3) is placed in an organic pollutant solution, and hydrogen peroxide is added, and the organic pollutants are all degraded after a period of time.

Example 8

1) Place the natural halloysite powder in a mixed solution of concentrated hydrochloric acid and concentrated phosphoric acid (volume ratio 7:1), ultrasonically disperse for 5~8 hours, centrifuge, and alternately wash with deionized water and absolute ethanol until the filtrate is neutral, 60 ℃ drying for use;

2) The product obtained in step 1) was placed in a mixed solution of sodium dodecylbenzenesulfonate and oxalic acid, stirred at 50-80 °C for 12-24 h, centrifuged, washed with deionized water until the filtrate was neutral, and dried at 60 °C spare;

3) Place the product obtained in step 2) in deionized water, and after ultrasonic dispersion for 10~30min, add FeSO ₄ ·7H ₂ O, and then ultrasonically disperse for 10~30min, the obtained suspension is placed in a vacuum bottle and vacuumized for 1~ 3h, ultrasonically disperse again, then vacuum and stand, repeat this 3~5 times, then add a mixed solution of KOH and _KNO3 , crystallize at 80~95°C for 2~5h, centrifuge, and dry to obtain the product;

4) The product obtained in step 3) is placed in an organic pollutant solution, and persulfate is added, and the organic pollutants are all degraded after a period of time.

Claims (3)

1. a preparation method for a halloysite-based micro-nano reactor for advanced catalytic oxidation, characterized in that in-situ growth of nanometer Fe ₃ O ₄ in natural halloysite nanotubes specifically comprises the following steps: 1) Acidification and purification of natural halloysite nanotubes: put natural halloysite powder in a mixed acid solution, ultrasonically disperse for 5-8 hours, centrifuge, alternately wash with deionized water and absolute ethanol until the filtrate is neutral, and dry at 60°C For standby use, the mixed acid used is two kinds of concentrated sulfuric acid, concentrated phosphoric acid, concentrated hydrochloric acid and concentrated nitric acid; 2) Internal modification of halloysite nanotubes: place the purified halloysite in a modifier solution with a certain concentration, stir at 50-80°C for 12-24 hours, centrifuge, and wash with deionized water until the filtrate is neutral, Dry at 60°C for later use, and the modifiers used are sulfamic acid, sodium dodecylbenzenesulfonate, oxalic acid, acetic acid, vinyl acetate, citric acid, sodium citrate, ethylenediaminetetraacetic acid, benzoic acid, peroxal Ammonium sulfate, toluene, xylene, propylmethyldimethoxysilane, N-aminoethyl-3-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-amino One or more combinations of propylmethyldimethoxysilane, methyl ethyl ketoxime, azobisisobutyronitrile, dibenzoyl peroxide, methyl methacrylate; 3) In situ growth in nano Fe ₃ O ₄ tubes: put the modified halloysite nanotubes in deionized water, ultrasonically disperse them for 10-30 min, add FeSO ₄ ·7H ₂ O, and ultrasonically disperse them for 10-30 min. The suspension is placed in a vacuum bottle and left to stand for 1-3 hours, then ultrasonically dispersed, and then vacuumed and allowed to stand. Repeat this for 3 to 5 times. Then, add mixed lye, crystallize at 80 to 95°C for 2 to 5 hours, and centrifuge. separation and drying to obtain a halloysite-based micro-nano reactor for in-situ growth of nano-Fe ₃ O ₄ in the tube; ₄ ) Application of advanced catalytic oxidation: The halloysite nanotubes with in-situ growth of nano- _Fe3O4 in the tube are placed in a certain concentration of organic pollutant solution, and oxidant is added, and advanced catalytic oxidation is carried out in a halloysite-based micro-nano reactor. The organic pollutants are efficiently degraded. 2. The preparation method of the halloysite-based micro-nano reactor for advanced catalytic oxidation according to claim 1, wherein the mixed alkali solution used in step 3) is NaOH, KOH, Na ₂ CO ₃ , K ₂ One or a combination of CO ₃ , NaHCO ₃ , KHCO ₃ , NaNO ₃ and KNO ₃ . 3. The preparation method of the halloysite-based micro-nano reactor for advanced catalytic oxidation according to claim 1, wherein the oxidant used in step 4) is hydrogen peroxide or persulfate.

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