Method for efficient degradation of toxic and refractory pollutants under photocatalysis of bi@bicocl

Abstract

The method for efficient degradation of toxic and refractory pollutants under photocatalysis of Bi@BiOCl belongs to the field of catalytic degradation. The method takes antibiotics such as tetracycline hydrochloride and ciprofloxacin, and endocrine pollutant bisphenol A as representative pollutants, and degrades them in the presence of catalyst Bi@BiOCl (the particle size of Bi element is about 3-6 nm) under the irradiation of a xenon lamp. The results show that the prepared Bi@BiOCl catalyst has obvious degradation effect on toxic and refractory pollutants, and the degradation efficiency of tetracycline hydrochloride and ciprofloxacin reaches 95.7% and 94.8% respectively within 20 minutes, and the degradation effect on endocrine pollutant bisphenol A is also remarkable.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for efficient degradation of toxic and refractory organic pollutants under photocatalysis by Bi@BiOCl photocatalytic material. BACKGROUND

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

[0003] Bismuth oxychloride (BiOCl) is composed of [Bi2O2] 2+ layers and Cl - layers connected by weak van der Waals forces, and has been widely studied in the field of photocatalysis, with excellent durability and redox capacity, easy synthesis, rich raw materials and unique layered structure. However, there is still a common problem that electrons and holes are easily recombined. Using 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, acting as electron traps. However, these noble metals are generally expensive, while bismuth metal has unique advantages such as low price, non-toxicity, easy transportation, and low effective carrier mass, making it an ideal candidate. The use of Bi@BiOCl has been reported, mainly for the degradation of various dyes and the oxidation of nitric oxide. Other BiOCl series photocatalysts take about 30-120 minutes 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 the method of Bi@BiOCl for almost complete degradation of antibiotics within 20 minutes under photocatalysis. SUMMARY

[0004] The present application aims at the deficiencies involved in the background art, and provides a method for efficient degradation of toxic and refractory organic pollutants under photocatalysis by Bi@BiOCl photocatalytic material. The present application degrades antibiotic pollutants tetracycline hydrochloride and ciprofloxacin, and endocrine pollutant bisphenol A, respectively. ZnCl2, KCl and Bi(NO3)3·5H2O are dispersed into deionized water in a certain proportion under magnetic stirring, stirred, then subjected to hydrothermal treatment, and after cooling, washed and dried to obtain the catalyst Bi@BiOCl of the present application. Under xenon lamp irradiation, tetracycline hydrochloride, ciprofloxacin and bisphenol A are degraded within 30 minutes, and the degradation efficiency is analyzed by ultraviolet-visible spectrophotometer. The results show that Bi@BiOCl has obvious degradation effect on toxic and refractory organic pollutants, and the degradation efficiency of tetracycline hydrochloride and ciprofloxacin is as high as 95.7% and 94.8% within 20 minutes, and the degradation effect on endocrine pollutant bisphenol A is also remarkable. In addition, when the concentration of the pollutants is increased to 50 times of the original concentration under the same conditions, high and rapid degradation results can also be obtained. The method of the present application is simple in operation and low in cost, and the degradation effect on tetracycline hydrochloride, ciprofloxacin and bisphenol A is much higher than the current reported level, and the method can efficiently photocatalytically degrade some antibiotic pollutants and endocrine pollutants existing in water, and has good prospects in wastewater treatment.

[0005] The present application is a method for rapid degradation of toxic and refractory organic pollutants under photocatalysis by Bi@BiOCl photocatalytic material, characterized by the following steps:

[0006] a. The aqueous solutions of tetracycline hydrochloride, ciprofloxacin and / or bisphenol A are respectively prepared into solutions with concentrations of 1×10 -5 mol / L and 5×10 -4 mol / L, and are subjected to ultrasonic treatment to make them into uniform and stable pollutant solutions;

[0007] b. The Bi@BiOCl catalyst is added into the pollutant solutions corresponding to step a, and is subjected to ultrasonic treatment for 3 minutes, then is stirred for dark adsorption process, and after adsorption for 30 minutes, 100 ml of the pollutant solution corresponds to every 20 mg of the Bi@BiOCl catalyst;

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

[0009] d. The taken sample is centrifuged, and the supernatant is taken to test the ultraviolet-visible absorption spectrum (the change in absorbance at the maximum absorption wavelength is tracked and monitored, and thus the degradation efficiency of the pollutant is analyzed).

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

[0011] In step c, the sampling time interval is every 5 minutes. -4 In addition, the degradation of high concentration pollution is carried out by taking tetracycline hydrochloride as an example under the condition that other conditions are kept unchanged, and the concentration is increased to 5*10

[0012] The results show that the prepared Bi@BiOCl catalyst has obvious degradation effect on toxic and refractory organic pollutants, and the degradation efficiency of tetracycline hydrochloride and ciprofloxacin is as high as 95.7% and 94.8% in only 20 minutes, and the degradation effect on endocrine pollutant bisphenol A is also remarkable. The method has the advantages of simple operation, low cost, good degradation effect on tetracycline hydrochloride, ciprofloxacin and bisphenol A, and can efficiently photocatalytically degrade part of antibiotic pollutants and endocrine pollutants existing in water.

[0013] The technical problem to be solved by the present application is to provide a method for rapid treatment of toxic and refractory organic pollutants under photocatalysis of Bi@BiOCl photocatalytic material, and to exhibit high catalytic activity. The high performance is achieved by respectively placing tetracycline hydrochloride, ciprofloxacin and bisphenol A solutions with concentrations of 1*10 -5 mol / L and 5*10 -4 mol / L under xenon lamp irradiation, and finally analyzing the degradation performance curve obtained by ultraviolet visible spectrophotometer. The good microstructure and optical properties of the Bi@BiOCl catalyst make the catalyst can be used in environmental pollution treatment, especially for the removal of high toxicity, low concentration of antibiotic and endocrine pollutants, and it is of great significance for exploring the preparation of new high-efficiency catalyst and new application, material design and environmental governance. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The XRD pattern of the photocatalyst powder of the present application is shown in the figure, and it can be seen from the figure that the sample is pure phase bismuth oxychloride.

[0015] Figure 2 The SEM graph of the photocatalyst of the present application is shown in the figure, and it can be seen from the figure that the sample presents a sheet morphology.

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

[0017] Figure 6 The degradation efficiency of the present application under xenon lamp irradiation is shown in the figure, wherein the amount of catalyst is 20 mg, the degradation curve of bisphenol A is represented by ■, the degradation curve of ciprofloxacin is represented by -●-, the degradation curve of tetracycline hydrochloride is represented by -▲-, and the degradation curve of tetracycline hydrochloride is represented by -★. -5 mol / L), the degradation curve of ciprofloxacin is represented by -●-, the degradation curve of tetracycline hydrochloride is represented by -▲-, and the degradation curve of tetracycline hydrochloride is represented by -★. -5 mol / L), the degradation curve of ciprofloxacin is represented by -●-, the degradation curve of tetracycline hydrochloride is represented by -▲-, and the degradation curve of tetracycline hydrochloride is represented by -★. -5 mol / L), the degradation curve of ciprofloxacin is represented by -●-, the degradation curve of tetracycline hydrochloride is represented by -▲-, and the degradation curve of tetracycline hydrochloride is represented by -★. -4 mol / L), the degradation curve of ciprofloxacin is represented by -●-, the degradation curve of tetracycline hydrochloride is represented by -▲-, and the degradation curve of tetracycline hydrochloride is represented by -★. DETAILED DESCRIPTION

[0018] The application will be described in detail below in combination with the drawings and examples:

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

[0020] Example 1:

[0021] a. Tetracycline hydrochloride was dissolved in water to prepare a solution with a concentration of 1×10 -5 mol / L, and ultrasonic treatment was performed 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 was taken as a mother liquor and reserved in a centrifuge tube. 20 mg of bismuth oxychloride catalyst was added to the 100 ml of pollutant solution, and after ultrasonic treatment for 3 min, a stirring and dark adsorption process was carried out. After adsorption for 30 min, 5 mL of sample was taken and reserved in a centrifuge tube;

[0023] c. The remaining solution system in step b was placed under xenon lamp irradiation, and every 5 min, 5 ml of sample was taken, and a total of 6 times;

[0024] d. After centrifugation of all the samples taken, the supernatant was tested for ultraviolet-visible absorption spectrum, and the degradation efficiency of the pollutant was analyzed. The degradation efficiency of the pollutant was 95.7% after 20 min.

[0025] Example 2:

[0026] a. Ciprofloxacin was dissolved in water to make a solution with a concentration of 1 x 10 -5 mol / L, and ultrasonic treatment was performed 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 was taken as a mother liquor and placed in a centrifuge tube for storage. 20 mg of bismuthyl chloride catalyst was added to the 100 ml of pollutant solution, and after ultrasonic treatment for 3 minutes, a stirring dark adsorption process was performed. After 30 minutes of adsorption, 5 mL of the sample was taken and placed in a centrifuge tube for storage;

[0028] c. The remaining solution system in step b was placed under a xenon lamp for irradiation. Every 5 minutes, 5 ml of sample was taken, and a total of 6 times;

[0029] d. After centrifugation of all the samples taken, the supernatant was tested for ultraviolet-visible absorption spectrum, and the pollutant degradation efficiency was analyzed. The pollutant degradation efficiency was 94.8% after 20 minutes.

[0030] Example 3:

[0031] a. Bisphenol A was dissolved in water to make a solution with a concentration of 1 x 10 -5 M, and ultrasonic treatment was performed 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 was taken as a mother liquor and placed in a centrifuge tube for storage. 20 mg of bismuthyl chloride catalyst was added to the 100 ml of pollutant solution, and after ultrasonic treatment for 3 minutes, a stirring dark adsorption process was performed. After 30 minutes of adsorption, 5 mL of the sample was taken and placed in a centrifuge tube for storage;

[0033] c. The remaining solution system in step b was placed under a xenon lamp for irradiation. Every 5 minutes, 5 ml of sample was taken, and a total of 6 times;

[0034] d. After centrifugation of all the samples taken, the supernatant was tested for ultraviolet-visible absorption spectrum, and the pollutant degradation efficiency was analyzed. The pollutant degradation efficiency was 73.6% after 30 minutes.

[0035] Example 4:

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

[0037] a. Tetracycline hydrochloride was dissolved in water to make a solution with a concentration of 5 x 10 -4 mol / L, and ultrasonic treatment was performed to make it a uniform and stable pollutant solution;

[0038] b. Take 100 ml of the solution obtained in step a in a 150 ml beaker and at the same time take 5 ml as mother liquor in a centrifuge tube to keep, add 20 mg of bismuthyl chloride catalyst to the 100 ml of contaminant solution, ultrasonic treatment for 3 minutes, then stirring dark adsorption process, after adsorption for 30 minutes, take 5 mL in a centrifuge tube to keep;

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

[0040] d. After centrifugation of all the samples taken, the supernatant is tested for UV-Vis absorption spectrum, and the degradation efficiency of the contaminant is analyzed. The degradation efficiency of the contaminant after 30 min is 65.0%.

Claims

1. Application of Bi@BiOCl photocatalytic material in the rapid degradation of toxic and recalcitrant antibiotics tetracycline hydrochloride and ciprofloxacin, and endocrine pollutant bisphenol A under photocatalysis; Preparation of Bi@BiOCl photocatalytic material: 1 mmol ZnCl2 and 2 mmol Bi(NO3)3⋅5H2O were dispersed in 30 mL deionized water under magnetic stirring, stirred for 30 min, 3 mmol KCl was added and stirred, and then hydrothermal treatment was carried out at 160℃ for 15 h to obtain the target product; Bi@BiOCl is Bi elemental particles loaded on BiOCl, and the particle size of Bi elemental particles is 3-6 nm; Follow these steps: a. Prepare antibiotics and endocrine contaminants to a concentration of 1×10⁻⁶. -5 mol / L - 5×10 -4 The solutions were prepared in mol / L concentration and subjected to ultrasonic treatment to make them homogeneous and stable solutions of contaminants. b. Add the Bi@BiOCl catalyst to the pollutant solution corresponding to step a, sonicate for 3 minutes, and then stir for dark adsorption. After adsorption for 30 minutes, each 20 mg of Bi@BiOCl catalyst corresponds to 100 ml of pollutant solution. c. Place the pollutant solution obtained in step b, which has reached adsorption-desorption equilibrium, under a xenon lamp for illumination. For each pollutant, take a sample into a sealed centrifuge tube at regular intervals. d. After centrifuging the sample taken in step c, take the supernatant and use a UV-Vis spectrophotometer to track the change of absorbance of pollutants at the maximum absorption wavelength. Analyze the trend and law of the change of pollutant absorbance over time under xenon lamp irradiation, and thus analyze the pollutant degradation efficiency. In step a, tetracycline hydrochloride and ciprofloxacin are antibiotic contaminants, while bisphenol A is an endocrine contaminant.

2. The application according to claim 1, characterized in that, In step c, sampling is performed every 5 minutes. Furthermore, using tetracycline hydrochloride as a typical example, the degradation of higher concentrations of pollutants is simulated while keeping other conditions consistent; specifically, the concentration is increased to 5 × 10⁻⁶. -4 mol / L, and conduct photocatalytic experiments under the same conditions.

3. The application according to claim 1, characterized in that Bi The @BiOCl catalyst achieved degradation efficiencies of 95.7% and 94.8% for tetracycline hydrochloride and ciprofloxacin, respectively, within just 20 minutes, and also showed significant degradation effects on the endocrine pollutant bisphenol A.

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