Method for degrading pollutants by piezoelectric-fenton system

Abstract

This invention belongs to the field of advanced oxidation technology, specifically relating to a method for degrading pollutants using a piezoelectric-Fenton-like system. It combines BaTiO3 and α-FeOOH materials to construct a BaTiO3 / α-FeOOH-based piezoelectric-Fenton-like system. This system couples the piezoelectric effect and the Fenton-like reaction; BaTiO3 generates piezoelectric electrons under ultrasonic stimulation, which participate in the degradation of Fe... 3+ / Fe 2+ In the transformation, promote Fe 3+ / Fe 2+ The cycle solved the problem of Fe in heterogeneous Fenton reactions. 3+ / Fe 2+ This addresses the persistent recycling problem, thereby improving the degradation efficiency of pollutants. Ultrasound-induced piezoelectric polarization in piezoelectric materials accelerates electron-hole transfer efficiency, thus enhancing the material's degradation capability. Experiments show that the BaTiO3 / α-FeOOH piezoelectric-Fenton-like system achieves 1.7 and 2.1 times the degradation efficiency of the organic pollutant Rhodamine B in water compared to BaTiO3 and α-FeOOH, respectively (reaction time 30 minutes).

Description

TECHNICAL FIELD

[0001] The application belongs to the field of advanced oxidation technology, and particularly relates to a method for degrading pollutants by a piezoelectric-Fenton system. BACKGROUND

[0002] The homogeneous Fenton technology mainly degrades organic pollutants by ·OH generated by Fenton reagent (Fe 2+ / H2O2), but the Fenton reaction must be carried out under acidic conditions with a pH less than 3, which limits the practical application of the Fenton technology. The use of iron-containing catalysts to establish a heterogeneous Fenton-like system is an effective strategy to solve this shortcoming, but the low Fe 3+ / Fe 2+ cycle reduces the catalytic efficiency. The piezoelectric effect is the deformation of a material under the action of external mechanical stress, which causes the displacement of the charge center of internal ions, generates a dipole moment and a built-in electric field, and at the same time, the electric charges with equal amount and opposite polarity appear on the opposite surfaces. The piezoelectric effect can effectively promote the separation and transmission of electrons and holes, improve the utilization rate of electrons and holes, and has received extensive attention and research in recent years. SUMMARY

[0003] The technical problem to be solved by the application is to provide a method for degrading pollutants by a piezoelectric-Fenton system, which combines piezoelectric material BaTiO3 with iron-containing material α-FeOOH, introduces piezoelectric effect in the heterogeneous Fenton-like reaction, constructs a piezoelectric-Fenton system, provides mechanical energy by ultrasonic waves, generates electrons in the piezoelectric material under the action of ultrasonic waves, promotes the Fe 3+ / Fe 2 + cycle, and improves the efficiency of the heterogeneous Fenton-like reaction to enhance the degradation of organic pollutants.

[0004] The technical scheme adopted is as follows:

[0005] A method for degrading pollutants by a piezoelectric-Fenton system, comprising the following steps:

[0006] (1) BaTiO3 / α-FeOOH preparation method:

[0007] Dissolve Fe(NO3)3·9H2O in deionized water, and dropwise add KOH under vigorous stirring; then add BaTiO3 powder to obtain a suspension, and after ultrasonic treatment, place the suspension in a Teflon-lined stainless steel high-pressure reaction kettle, and place the high-pressure reaction kettle in a gas bath constant temperature oscillator to keep shaking for 6-12 hours;

[0008] After the reaction, the product is purified by washing with distilled water and anhydrous ethanol, vacuum dried to obtain BaTiO3 / alpha-FeOOH composite catalyst;

[0009] (2) The method for degrading pollutants by piezoelectric-Fenton system:

[0010] The BaTiO3 / alpha-FeOOH composite catalyst is placed in an aqueous reaction system, and hydrogen peroxide is added; the aqueous reaction system is placed in circulating cooling water, and degradation is carried out under ultrasonic action.

[0011] Preferably, in the step (1), the molar and volume ratio of Fe(NO3)3·9H2O to deionized water is (3-6):5 mmol / mL.

[0012] Preferably, in the step (1), the molar ratio of KOH to Fe(NO3)3·9H2O added is 49-98:12-24.

[0013] Preferably, in the step (1), the molar ratio of Ba / Fe is 1:4-4:1; and the ultrasonic treatment time of the suspension is 20-30 min.

[0014] Preferably, in the step (1), the oscillation temperature in the high-pressure reaction kettle is 80-120℃, and the rotation speed is 159-259 rad / min.

[0015] Preferably, in the step (1), the vacuum drying is carried out in a vacuum oven at 70℃ for 24 hours.

[0016] Preferably, in the step (2), the mass of the BaTiO3 / alpha-FeOOH composite catalyst to the volume of the aqueous reaction system is 20-100 mg / 100-500 mL.

[0017] Preferably, hydrogen peroxide is further added, and the concentration of the aqueous reaction system is 30-90 mmol / L.

[0018] Preferably, the circulating cooling water is controlled at a temperature of 25-40℃, and pH=7.

[0019] Preferably, the ultrasonic degradation power is 100-600 W.

[0020] Compared with the prior art, the method has the beneficial effects that:

[0021] The method for degrading pollutants by piezoelectric-Fenton system based on BaTiO3 / alpha-FeOOH is proposed, and the Fe 2+The regeneration problem is solved by combining BaTiO3 and alpha-FeOOH to construct a piezoelectric-Fenton system based on BaTiO3 / alpha-FeOOH, which couples piezoelectric effect and Fenton-like reaction, and the piezoelectric electron generated by BaTiO3 under the action of mechanical energy of ultrasonic waves participates in the conversion of Fe 3+ / Fe 2+ , promotes the Fe 3+ / Fe 2+ cycle, solves the problem of persistent cycle of Fe 3+ / Fe 2+ in the heterogeneous Fenton-like reaction, and further improves the degradation efficiency of pollutants.

[0022] Meanwhile, the piezoelectric polarization effect of the piezoelectric material caused by ultrasonic waves can accelerate the transfer efficiency of electron holes, thereby improving the degradation capacity of the material. Experiments prove that the efficiency of the BaTiO3 / alpha-FeOOH piezoelectric-Fenton system in degrading organic pollutants rhodamine B in water is 1.7 and 2.1 times that of BaTiO3 and alpha-FeOOH respectively (reaction time 30 minutes).

[0023] The efficiency of the BaTiO3 / alpha-FeOOH piezoelectric-Fenton system in degrading demethylchlortetracycline in water is about 1.5 times that of BaTiO3 (reaction time 10 minutes), and complete degradation and removal of demethylchlortetracycline (5mg / L, 100mL) can be achieved within 10 minutes. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a structure diagram of the piezoelectric-Fenton reaction system of the application;

[0025] Figure 2 It is an XRD diagram of BaTiO3 / alpha-FeOOH of the application;

[0026] Figure 3 It is an SEM diagram of BaTiO3 / alpha-FeOOH of the application;

[0027] Figure 4 It is a comparison diagram of the effect of degrading rhodamine B in water;

[0028] Figure 5 It is a comparison diagram of the effect of degrading demethylchlortetracycline in water.

[0029] In the figure, 1 is a reaction tank, 2 is a stirrer, 3 is circulating cooling water, and 4 is an ultrasonic generator. DETAILED DESCRIPTION

[0030] The drawings are only used for illustrative description; some known structures and their descriptions in the drawings can be omitted, therefore, cannot be understood as a limitation on the application; the chemical reagents and raw materials used in the application can be purchased through conventional commercial channels if not specifically mentioned.

[0031] Example 1

[0032] A method for degrading pollutants by a piezoelectric-Fenton-like system, comprising the following steps:

[0033] (1) Preparation method of BaTiO3 / α-FeOOH:

[0034] Dissolve 12 mmol Fe(NO3)3·9H2O in 20 mL of deionized water, add 49 mmol KOH dropwise under vigorous stirring, add BaTiO3 powder (Fe / Ba = 1:1, molar ratio) to obtain a suspension, ultrasonic treatment for 30 minutes, place in a 50 mL Teflon-lined stainless steel high-pressure reaction kettle, place the high-pressure reaction kettle in a gas bath constant temperature oscillator, oscillate at a temperature of 80°C and a rotation speed of 159 rad / min for 6 hours, purify by washing with distilled water and anhydrous ethanol, dry in a vacuum oven at 70°C for 24 hours to obtain BaTiO3 / α-FeOOH. As shown in Figure 2 , it is an XRD pattern of the generated BaTiO3 / α-FeOOH, Figure 3 , it is an SEM pattern of the generated BaTiO3 / α-FeOOH.

[0035] (2) Method for degrading pollutants by a piezoelectric-Fenton-like system:

[0036] As shown in Figure 1 , 50 mg of BaTiO3 / α-FeOOH composite catalyst is placed in a 100 mL aqueous reaction system (reaction tank 1), hydrogen peroxide is added, the concentration is 30 mmol / L, the stirrer 2 is continuously stirred, the ultrasonic generator 4 is used for ultrasonic treatment, the degradation is carried out under the action of ultrasonic waves with a power of 300 W, the circulating cooling water 3 is continuously circulated to control the temperature at 25°C, pH = 7. Under the piezoelectric-Fenton-like system, the degradation of demethylchlortetracycline in water is obviously improved (see Figure 5 ).

[0037] Example 2

[0038] A method for degrading pollutants by a piezoelectric-Fenton-like system, comprising the following steps:

[0039] (1) Preparation method of BaTiO3 / α-FeOOH:

[0040] Dissolve 24 mmol Fe(NO3)3·9H2O in 20 mL deionized water, add 98 mmol KOH drop by drop under vigorous stirring, add BaTiO3 powder (Fe / Ba = 1:2, molar ratio) to obtain a suspension, ultrasonic treatment for 30 minutes, place in a 50 mL Teflon-lined stainless steel high-pressure reaction kettle, place the high-pressure reaction kettle in a gas bath constant temperature oscillator, oscillate at a temperature of 80°C and a rotation speed of 159 rad / min for 8 hours, purify by washing with distilled water and anhydrous ethanol, and dry in a vacuum oven at 70°C for 24 hours to obtain BaTiO3 / α-FeOOH.

[0041] (2) Method for degrading pollutants by a piezoelectric-Fenton system:

[0042] Place 80 mg of BaTiO3 / α-FeOOH composite catalyst in a 300 mL aqueous reaction system, add hydrogen peroxide with a concentration of 50 mmol / L, and degrade under ultrasonic action at a power of 500 W, with circulating cooling water to control the temperature at 25°C and pH = 7. The effect of degrading rhodamine B in water under the piezoelectric-Fenton system is significantly improved (see Figure 4 ).

[0043] The other aspects not mentioned are the same as in Example 1.

[0044] Comparative Example 1

[0045] Place 80 mg of BaTiO3 / α-FeOOH composite catalyst in a 300 mL aqueous reaction system, add hydrogen peroxide with a concentration of 50 mmol / L, and degrade under ultrasonic action at a power of 500 W, with circulating cooling water to control the temperature at 25°C and pH = 7. The effect of degrading rhodamine B in water is shown in Figure 4 .

[0046] Comparative Example 2

[0047] Place 80 mg of BaTiO3 / α-FeOOH composite catalyst in a 300 mL aqueous reaction system, add hydrogen peroxide with a concentration of 50 mmol / L, and degrade under ultrasonic action at a power of 500 W, with circulating cooling water to control the temperature at 25°C and pH = 7. The effect of degrading rhodamine B in water is shown in Figure 4 .

[0048] Comparative Example 3

[0049] Degrade rhodamine B in water under ultrasonic action at a power of 500 W, with circulating cooling water to control the temperature at 25°C and pH = 7, and the effect is shown in Figure 4 .

[0050] Comparative Example 4

[0051] 80mg BaTiO3 / α-FeOOH composite catalyst was placed in a 300mL aqueous reaction system, and degradation was carried out under the action of 500W ultrasonic waves, with circulating cooling water controlling the temperature at 25℃ and pH=7. The effect of degrading rhodamine B in water is shown in Figure 4 .

[0052] Comparative Example 5

[0053] 80mg α-FeOOH catalyst was placed in a 300mL aqueous reaction system, and hydrogen peroxide was added at a concentration of 50mmol / L, and degradation was carried out under the action of 500W ultrasonic waves, with circulating cooling water controlling the temperature at 25℃ and pH=7. The effect of degrading rhodamine B in water is shown in Figure 4 .

[0054] As shown in Figure 4 , the effect of degrading rhodamine B in water under the piezoelectric-Fenton system constructed in Example 2 was compared with that of Comparative Examples 1-5, and experiments proved that the efficiency of BaTiO3 / α-FeOOH piezoelectric-Fenton system in degrading organic pollutants rhodamine B in water was 1.7 and 2.1 times that of BaTiO3 and α-FeOOH, respectively. The effects of Comparative Examples 1-5 were far less than that of the present example.

[0055] Comparative Example 6

[0056] 50mg BaTiO3 catalyst was placed in a 100mL aqueous reaction system (reaction tank 1), and hydrogen peroxide was added at a concentration of 30mmol / L, and the stirrer 2 was continuously stirred, and ultrasonic waves were generated by the ultrasonic wave generator 4, and degradation was carried out under the action of 300W ultrasonic waves, with circulating cooling water 3 continuously flowing to control the temperature at 25℃ and pH=7. The effect of degrading terramycin in water is shown in Figure 5 .

[0057] As shown in Figure 5 , the effect of degrading terramycin in water under the piezoelectric-Fenton system constructed in Example 1 was obviously improved compared with the degradation effect of Comparative Example 6. The efficiency of BaTiO3 / α-FeOOH piezoelectric-Fenton system in degrading terramycin in water was about 1.5 times that of BaTiO3, and complete degradation and removal of terramycin (5mg / L, 100mL) could be achieved.

[0058] Of course, the above description is not a limitation on the present application, and the present application is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the essential scope of the present application should also be within the protection scope of the present application.

Claims

1. A method for degrading pollutants using a piezoelectric-Fenton-like system, characterized in that, Includes the following steps: (1) BaTiO3 / α-FeOOH preparation method: Fe(NO3)3·9H2O was dissolved in deionized water, and KOH was added dropwise under vigorous stirring. BaTiO3 powder was then added to obtain a suspension. After ultrasonic treatment, the suspension was placed in a Teflon-lined stainless steel high-pressure reactor. The high-pressure reactor was then placed in a gas bath constant temperature shaker and shaken for 6 to 12 hours. After the reaction was complete, the product was washed and purified with distilled water and anhydrous ethanol, and then dried under vacuum to obtain the BaTiO3 / α-FeOOH composite catalyst. (2) Methods for degrading pollutants using piezoelectric-Fenton-like systems: The BaTiO3 / α-FeOOH composite catalyst was placed in an aqueous reaction system, and then hydrogen peroxide was added. The aqueous reaction system was placed in circulating cooling water and degraded under ultrasonic treatment.

2. The method for degrading pollutants using a piezoelectric-Fenton-like system according to claim 1, characterized in that, In step (1), the molar and volume ratio of Fe(NO3)3·9H2O to deionized water is (3~6:5) mmol / mL.

3. The method for degrading pollutants using a piezoelectric-Fenton-like system according to claim 1, characterized in that, In step (1), the molar ratio of KOH to Fe(NO3)3·9H2O is 49-98:12-24.

4. The method for degrading pollutants using a piezoelectric-Fenton-like system according to claim 1, characterized in that, In step (1), the molar ratio of Ba / Fe is 1:4 to 4:1; the ultrasonic treatment time of the suspension is 20 to 30 minutes.

5. The method for degrading pollutants using a piezoelectric-Fenton-like system according to claim 1, characterized in that, In step (1), the temperature of the oscillation in the high-pressure reactor is 80-120℃ and the rotation speed is 159-259 rad / min.

6. The method for degrading pollutants using a piezoelectric-Fenton-like system according to claim 1, characterized in that, In step (1), the vacuum drying is carried out in a vacuum oven at 70°C for 24 hours.

7. The method for degrading pollutants using a piezoelectric-Fenton-like system according to claim 1, characterized in that, In step (2), the mass ratio of the BaTiO3 / α-FeOOH composite catalyst to the volume ratio of the aqueous reaction system is 20-100 mg / 100-500 mL.

8. The method for degrading pollutants using a piezoelectric-Fenton-like system according to claim 7, characterized in that, Then add hydrogen peroxide, and the concentration in the aqueous reaction system is 30-90 mmol / L.

9. The method for degrading pollutants using a piezoelectric-Fenton-like system according to claim 8, characterized in that, The circulating cooling water temperature is controlled at 25–40℃, and the pH is 7.

10. The method for degrading pollutants using a piezoelectric-Fenton-like system according to claim 9, characterized in that, During ultrasonic degradation, the power is 100-600W.

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