Method for efficiently degrading toxic and refractory pollutants by Bi-coated BiOCl under photocatalysis

Abstract

The invention discloses a method for efficiently degrading toxic and refractory pollutants by Bi-coated BiOCl under photocatalysis, and belongs to the field of catalytic degradation. According to the method, antibiotics such as tetracycline hydrochloride and ciprofloxacin and an endocrine pollutant bisphenol A are taken as representative pollutants, and the representative pollutants are degraded under irradiation of a xenon lamp in the presence of a catalyst Bi (at) BiOCl (wherein the particle size of elemental Bi is about 3-6 nm). Results show that the prepared Bi-coated BiOCl catalyst has an obvious degradation effect on toxic and refractory pollutants, the degradation efficiency of tetracycline hydrochloride and ciprofloxacin within only 20 minutes is as high as 95.7% and 94.8%, and the degradation effect on an endocrine pollutant bisphenol A is also relatively obvious.

Description

Technical Field

[0001] The invention relates to a method for efficiently degrading toxic and difficult-to-degrade organic pollutants using a Bi@BiOCl photocatalytic material under photocatalysis. Background Art

[0002] Modern medicine widely uses antibiotics, saving countless lives. However, most antibiotics are not absorbed by humans and animals, but are excreted as metabolites. The abuse and excessive discharge of antibiotics will directly inhibit the normal growth of organisms in soil and water, seriously damage the environmental ecosystem, and pose a serious threat to human health. Therefore, it is necessary to find effective technologies to remove antibiotics. Photocatalytic technology, as a new type of catalytic oxidation technology, is a feasible strategy to solve the antibiotic environmental pollution crisis with its advantages of environmental protection, economy, energy saving, and easy operation.

[0003] Bismuth oxychloride (BiOCl) is made from [Bi2O2] 2+ Layer and Cl - Layers are connected by weak van der Waals forces and have been widely studied in the field of photocatalysis. They have excellent durability and redox ability, are easy to synthesize, have abundant raw materials and unique layered structures. However, there is still a common problem that electrons and holes are easy to recombine. The use of metal semiconductor systems is an effective strategy to solve this problem. Adding metal nanoparticles, such as gold and silver, to semiconductors can effectively promote their photocatalytic performance because metals can form Schottky barriers at the interface and act as electron traps. However, these precious metals are generally expensive, while metallic bismuth has unique advantages such as low price, non-toxicity, easy transportation, and low effective carrier mass, making it an ideal candidate material. The use of Bi@BiOCl has been reported, mainly for the degradation of various dyes and oxidation of nitric oxide. It takes about 30-120 minutes for other BiOCl series photocatalysts to degrade 90% of tetracycline hydrochloride and about 80-300 minutes to degrade 90% of ciprofloxacin. However, there is no report on how to accelerate the photocatalysis of Bi@BiOCl, especially on how to almost completely degrade antibiotics within 20 minutes under photocatalysis by Bi@BiOCl. Summary of the invention

[0004] The purpose of the present invention is to provide a method for efficiently degrading toxic and difficult-to-degrade organic pollutants using a Bi@BiOCl photocatalytic material under photocatalysis in view of the deficiencies involved in the background technology. The invention uses antibiotic pollutants tetracycline hydrochloride and ciprofloxacin and endocrine pollutant bisphenol A as pollutants for degradation. ZnCl2, KCl and Bi(NO3)3·5H2O are dispersed in deionized water in a certain proportion under magnetic stirring, stirred, and then subjected to hydrothermal treatment. After cooling, washing and drying, the catalyst Bi@BiOCl of the present invention can be obtained. Under the irradiation of a xenon lamp, the degradation efficiency of tetracycline hydrochloride, ciprofloxacin and bisphenol A is analyzed by ultraviolet-visible spectrophotometer within 30 minutes. The results show that Bi@BiOCl has a significant degradation effect on toxic and difficult-to-degrade organic pollutants. The degradation efficiency of tetracycline hydrochloride and ciprofloxacin is as high as 95.7% and 94.8% in just 20 minutes, and the degradation effect on the endocrine pollutant bisphenol A is also significant. In addition, other conditions remain unchanged, and the pollutant concentration is increased to 50 times the original, and an efficient and rapid degradation result can also be obtained. The method of the present invention is simple to operate, low in cost, and has a degradation effect on tetracycline hydrochloride, ciprofloxacin and bisphenol A that is much higher than the currently reported level. It can efficiently photocatalytically degrade some antibiotic pollutants and endocrine pollutants in water, and has good prospects in sewage treatment.

[0005] The method for rapidly degrading toxic and difficult-to-degrade organic pollutants by using the Bi@BiOCl photocatalytic material of the present invention under photocatalysis is characterized by being carried out according to the following steps:

[0006] a. Prepare aqueous solutions of tetracycline hydrochloride, ciprofloxacin and / or bisphenol A to a concentration of 1×10 -5 mol / L and 5×10 -4 mol / L solutions and ultrasonic treatment to make them into uniform and stable pollutant solutions;

[0007] b. The Bi@BiOCl catalyst was added to the pollutant solution corresponding to step a, and then subjected to stirring dark adsorption after ultrasonic treatment for 3 minutes. After adsorption for 30 minutes, each 20 mg of Bi@BiOCl catalyst corresponded to 100 ml of pollutant solution;

[0008] c. The solution system obtained in step b is irradiated under a xenon lamp or visible light, and samples are taken at intervals for each pollutant;

[0009] d. After the sample is centrifuged, the supernatant is taken to test the UV-visible absorption spectrum (track and monitor the absorbance change at the maximum absorption wavelength to analyze the pollutant degradation efficiency) to analyze the pollutant degradation efficiency.

[0010] In step a, tetracycline hydrochloride and ciprofloxacin are antibiotic pollutants, and bisphenol A is an endocrine pollutant.

[0011] In step c, the sampling interval is once every 5 minutes. In addition, taking tetracycline hydrochloride as an example, the degradation of high-concentration pollution is carried out under the same other conditions, specifically, the concentration is increased to 5×10 -4 mol / L, and carried out photocatalytic experiments under the same conditions.

[0012] The results show that the prepared Bi@BiOCl catalyst has a significant degradation effect on toxic and difficult-to-degrade organic pollutants. The degradation efficiency of tetracycline hydrochloride and ciprofloxacin is as high as 95.7% and 94.8% in just 20 minutes. The degradation effect on the endocrine pollutant bisphenol A is also significant. The method of the present invention is simple to operate, low in cost, has a good degradation effect on tetracycline hydrochloride, ciprofloxacin and bisphenol A, and can efficiently photocatalytically degrade some antibiotic pollutants and endocrine pollutants in water.

[0013] The technical problem to be solved by the present invention is to provide a method for the rapid treatment of toxic and difficult-to-degrade organic pollutants by Bi@BiOCl photocatalytic materials under photocatalysis, and to show high catalytic activity. This high-end performance is achieved by respectively converting the concentration of 1×10 -5 mol / L and the concentration is 5×10 -4 mol / L tetracycline hydrochloride, ciprofloxacin and bisphenol A solutions were irradiated under a xenon lamp, and finally analyzed by UV-visible spectrophotometer to obtain degradation performance curves. The good microstructure and optical properties of the Bi@BiOCl catalyst make it possible to use the catalyst in the treatment of environmental pollutants, especially for the removal of highly toxic, low-concentration antibiotics and endocrine pollutants, which is of great significance for the exploration of the preparation and new applications of new high-efficiency catalysts, material design and environmental management. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the diffraction XRD spectrum of the photocatalyst powder of the present invention. It can be seen from the figure that the sample is pure phase bismuth oxychloride.

[0015] Figure 2 This is a SEM image of the photocatalyst of the present invention. As can be seen from the image, the sample has a flake-like morphology.

[0016] Figure 3 , Figure 4 , Figure 5 is the XPS spectrum of the photocatalyst of the present invention, which corresponds to the spectra of Bi, O, and Cl respectively. It can be seen that the sample is BiOCl, and Figure 2The peak of Bi element can be observed in the sample, proving the existence of Bi@BiOCl.

[0017] Figure 6 is the degradation efficiency diagram of the present invention under xenon lamp irradiation, wherein the amount of catalyst used is 20 mg, -■- is the degradation curve of bisphenol A (1×10 -5 mol / L), -●- is the degradation curve of ciprofloxacin (1×10 -5 mol / L), -▲- is the degradation curve of tetracycline hydrochloride (1×10 -5 mol / L), -★- is the degradation curve of tetracycline hydrochloride (5×10 -4 mol / L). DETAILED DESCRIPTION

[0018] The invention is described in detail below with reference to the accompanying drawings and examples:

[0019] Preparation of Bi@BiOCl photocatalytic material: 1mmol ZnCl2 and 2mmol Bi(NO3)3·5H2O were dispersed into 30mL deionized water under magnetic stirring, stirred for 30min, KCl (3mmol) was added and stirred, and then hydrothermally treated at 160℃ for 15h to obtain the target product. Bi@BiOCl is Bi single substance particles loaded on BiOCl, and the particle size of Bi single substance is about 3-6nm.

[0020] Embodiment 1:

[0021] a. Dissolve tetracycline hydrochloride in water to a concentration of 1×10 -5 mol / L solution and ultrasonic treatment to make it a uniform and stable pollutant solution;

[0022] b. 100 ml of the solution obtained in step a was placed in a 150 ml beaker and 5 ml of the mother liquor was placed in a centrifuge tube for retention. 20 mg of bismuth oxychloride catalyst was added to the 100 ml pollutant solution. After ultrasonic treatment for 3 minutes, the dark adsorption process was stirred. After 30 minutes of adsorption, 5 ml of the sample was placed in a centrifuge tube for storage.

[0023] c. The remaining solution system in step b is placed under a xenon lamp and sampled every 5 minutes, 5 ml each time, for a total of 6 times;

[0024] d. After centrifuging all the samples, the supernatant was tested for UV-visible absorption spectrum to analyze the pollutant degradation efficiency. After 20 minutes, the pollutant degradation efficiency was 95.7%.

[0025] Embodiment 2:

[0026] a. Dissolve ciprofloxacin in water to a concentration of 1×10 -5 mol / L solution and ultrasonic treatment to make it a uniform and stable pollutant solution;

[0027] b. 100 ml of the solution obtained in step a was placed in a 150 ml beaker and 5 ml of the mother liquor was placed in a centrifuge tube for retention. 20 mg of bismuth oxychloride catalyst was added to the 100 ml pollutant solution. After ultrasonic treatment for 3 minutes, the dark adsorption process was stirred. After 30 minutes of adsorption, 5 ml of the sample was placed in a centrifuge tube for storage.

[0028] c. The remaining solution system in step b is placed under a xenon lamp and sampled every 5 minutes, 5 ml each time, for a total of 6 times;

[0029] d. After centrifuging all the samples, the supernatant was tested for UV-visible absorption spectrum to analyze the pollutant degradation efficiency. After 20 minutes, the pollutant degradation efficiency was 94.8%.

[0030] Embodiment 3:

[0031] a. Dissolve bisphenol A in water to a concentration of 1×10 -5 M solution and ultrasonic treatment to make it a uniform and stable pollutant solution;

[0032] b. 100 ml of the solution obtained in step a was placed in a 150 ml beaker and 5 ml of the mother liquor was placed in a centrifuge tube for retention. 20 mg of bismuth oxychloride catalyst was added to the 100 ml pollutant solution. After ultrasonic treatment for 3 minutes, the dark adsorption process was stirred. After 30 minutes of adsorption, 5 ml of the sample was placed in a centrifuge tube for storage.

[0033] c. The remaining solution system in step b is placed under a xenon lamp and sampled every 5 minutes, 5 ml each time, for a total of 6 times;

[0034] d. After centrifuging all the samples, the supernatant was tested for UV-visible absorption spectrum to analyze the pollutant degradation efficiency. After 30 minutes, the pollutant degradation efficiency was 73.6%.

[0035] Embodiment 4:

[0036] Among the three pollutants, tetracycline hydrochloride is taken as a typical example to demonstrate the degradation effect of the catalyst of the present invention on high-concentration pollutants.

[0037] a. Dissolve tetracycline hydrochloride in water to a concentration of 5×10 -4 mol / L solution and ultrasonic treatment to make it a uniform and stable pollutant solution;

[0038] b. 100 ml of the solution obtained in step a was placed in a 150 ml beaker and 5 ml of the mother liquor was placed in a centrifuge tube for retention. 20 mg of bismuth oxychloride catalyst was added to the 100 ml pollutant solution. After ultrasonic treatment for 3 minutes, the dark adsorption process was stirred. After 30 minutes of adsorption, 5 ml of the sample was placed in a centrifuge tube for storage.

[0039] c. The remaining solution system in step b was placed under a xenon lamp and sampled every 2 minutes for the first 10 minutes, 5 ml each time, for a total of 5 times, and sampled every 5 minutes for 20 minutes, for a total of 4 times;

[0040] d. After centrifuging all the samples, the supernatant was tested for UV-visible absorption spectrum to analyze the pollutant degradation efficiency. After 30 minutes, the pollutant degradation efficiency was 65.0%.

Claims

1. Application of Bi@BiOCl photocatalytic materials in the rapid degradation of toxic and difficult-to-degrade antibiotics tetracycline hydrochloride, ciprofloxacin and endocrine pollutant bisphenol A under photocatalysis.

2. A method for rapidly degrading toxic and difficult-to-degrade organic pollutants using Bi@BiOCl photocatalytic materials under photocatalysis, characterized in that: Follow these steps: a) Prepare antibiotics and endocrine pollutants to a concentration of 1×10 -5 mol / L-5×10 -4 mol / L solutions and ultrasonic treatment to make them into uniform and stable pollutant solutions; b) adding the Bi@BiOCl catalyst to the pollutant solution corresponding to step a, respectively, and performing a stirring dark adsorption process after ultrasonic treatment for 3 minutes. After adsorption for 30 minutes, each 20 mg of Bi@BiOCl catalyst corresponds to 100 ml of pollutant solution; c) placing the pollutant solution obtained in step b and having reached adsorption-desorption equilibrium under a xenon lamp for illumination, and taking a sample of each pollutant at regular intervals into a sealed centrifuge tube; d) After centrifuging the sample taken out in step c, taking the supernatant and tracking the absorbance change of the pollutant at the maximum absorption wavelength by a UV-visible spectrophotometer, thereby analyzing the trend and law of the absorbance change of the pollutant under xenon light over time, and thereby analyzing the pollutant degradation efficiency; In step a, tetracycline hydrochloride and ciprofloxacin are antibiotic pollutants, and bisphenol A is an endocrine pollutant.

3. The method according to claim 2, characterized in that In step c, the sampling interval is once every 5 minutes. In addition, tetracycline hydrochloride is used as a typical representative to simulate the degradation of higher concentration pollutants while keeping other conditions the same, specifically, its concentration is increased to 5×10 -4 mol / L, and carried out photocatalytic experiments under the same conditions.

4. The method according to claim 2, characterized in that Bi @BiOCl catalyst can degrade tetracycline hydrochloride and ciprofloxacin by 95.7% and 94.8% in just 20 minutes, and also has a significant effect on the degradation of endocrine pollutant bisphenol A.

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