Construction and application of photoelectrochemical sensor for detection and degradation of bisphenol A in microplastics

Abstract

The present invention discloses a photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics, and its preparation and application. A CoO / SCS composite material with photoelectric activity is constructed, and a PEC sensor is constructed based on the CoO / SCS material. Bisphenol A released from microplastics is used as the target for PEC detection. The PEC process converts light energy into electrical energy and chemical energy, reducing the dependence on bias voltage, thereby improving the precision of detection. A photoelectrocatalytic system is constructed to achieve catalytic degradation of bisphenol A by changing the catalytic conditions. The present invention combines the advantages of optical and electrochemical methods, and has the advantages of simple operation, rapid reaction, high sensitivity, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectrochemical sensors, and in particular to the construction and application of a photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics. Background Art

[0002] In recent years, plastic pollution has brought new threats to humans - the production of microplastics and environmental hormones. Microplastics, as the name suggests, are tiny plastic particles, usually derived from degraded plastic fragments. In 2018, scientists detected nine types of plastic particles between 50 and 500 microns in human feces for the first time, but it is not clear how microplastics enter the human body. It is initially speculated that they may enter the human body through the "food chain" such as marine life, bottled water and food. However, more importantly, the extent of the impact of microplastics on human health and whether this impact is related to the "threshold" is currently unclear.

[0003] As we all know, many physiological activities of the human body are regulated by hormones secreted in the body. However, there are many natural or synthetic exogenous compounds that can produce hormone-like effects on the human body, usually called environmental hormones (Endocrine Disrupting Chemicals, EDCs), also known as endocrine disruptors. The structure of environmental hormones is similar to that of human hormones, and they interfere with the synthesis, secretion, transportation and efficacy of natural hormones, thereby affecting human homeostasis, reproduction, growth and development. At present, chemical substances such as phthalates, polychlorinated biphenyls, dioxins, alkylphenols, and bisphenol A (BPA) have been proven to have the effect of environmental hormones. Among them, bisphenol A comes from plastic products and is also the focus of this article.

[0004] Bisphenol A (BPA) is one of the most widely used industrial compounds in the world. It is widely used in the production of plastic products such as plastic bottles, textile clothing and food packaging. BPA in the environment can harm human health through the food chain and direct contact. Bisphenol A can seep out of plastic or resin containers or packaging and enter food or drinking water together with micro-nano plastics, especially under high temperature or high fat conditions. The higher the temperature, the more bisphenol A remaining in polycarbonate is released, and the faster it is. Bisphenol A is one of the endocrine disruptors in microplastics, an estrogen disrupting substance. When BPA molecules bind to estrogen receptors, endocrine disorders occur, leading to hormonal imbalance, affecting reproductive development, and increasing the incidence of cancer. A study shows that even low concentrations (0.1-10 μM) of BPA may cause serious harm to human health, such as testicular cancer, ovarian cancer, and breast cancer.

[0005] In industry, bisphenol A is used to synthesize materials such as polycarbonate (PC) and epoxy resin. Since the 1960s, it has been used to make plastic (milk) bottles, sippy cups for infants, and the inner coating of food and beverage (milk powder) cans. In short, BPA is everywhere, from mineral water bottles, medical devices to the inside of food packaging.

[0006] Polycarbonate is a high-performance transparent plastic that uses bisphenol A, a significant endocrine disrupting compound, in its production process. Bisphenol A leaches from improperly handled plastic products and enters the environment through wastewater, pollutants, sediments, surface water, and groundwater from the plastic production industry. Therefore, it is urgent to develop high-precision and high-sensitivity BPA detection and degradation technologies in the fields of environmental monitoring and food safety. Summary of the invention

[0007] The present invention achieves the technical effect of high-precision and high-sensitivity detection and degradation of BPA by providing the construction and application of a photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics.

[0008] The present invention provides a method for preparing a photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics, comprising:

[0009] Co(NO3)2·6H2O, NH4F and CO(NH2)2 are mixed in ethylene glycol to obtain a mixed solution;

[0010] The mixed solution was placed in a high pressure reactor and reacted at 90-100° C. for 6-8 hours;

[0011] The reacted solution is dried under vacuum conditions at 60-80° C. for 6-10 hours to obtain CoO;

[0012] Dispersing the CoO, CoCl2·6H2O, SnCl4·5H2O and L-cysteine ​​in deionized water to obtain a suspension;

[0013] The suspension is reacted in a high pressure reactor at 160-180° C. for 10-14 hours to generate a CoO / SCS composite material;

[0014] After the CoO / SCS composite material is dispersed in a mixed solution of ethanol and an aqueous solution, it is drop-coated on the surface of an ITO electrode.

[0015] Specifically, the mixed solution is placed in a high pressure reactor and reacted at 90-100° C. for 6-8 hours, comprising:

[0016] The mixed solution was placed in a polytetrafluoroethylene autoclave and reacted at 95° C. for 6 hours.

[0017] Specifically, the CoO, CoCl2·6H2O, SnCl4·5H2O and L-cysteine ​​are dispersed in deionized water to obtain a suspension, comprising:

[0018] The CoO, CoCl2·6H2O, SnCl4·5H2O and L-cysteine ​​are added into deionized water, dispersed by ultrasonication for 10 minutes, and stirred for 20 minutes to obtain the suspension.

[0019] Specifically, after the CoO / SCS composite material is generated, the method further comprises:

[0020] The CoO / SCS composite was washed alternately with deionized water and ethanol and then dried under vacuum at 60 °C for 10 h.

[0021] The present invention also provides a photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics, which is prepared according to the above method.

[0022] The present invention also provides the application of the above-mentioned photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics, including: detecting the content of bisphenol A in microplastics or degrading bisphenol A in microplastics.

[0023] Specifically, the detection of the content of bisphenol A in microplastics includes:

[0024] The microplastic extract, the ITO electrode, the saturated calomel reference electrode and the platinum counter electrode are placed in a K2SO4 electrolyte, illuminated by light, and an IT test is performed to obtain photocurrent data ΔI;

[0025] Substitute the photocurrent data ΔI into the linear fitting equation ΔI=-0.33×lgC BPA -5.30 Calculate the concentration of bisphenol A in the sample C BPA .

[0026] Specifically, the degradation of bisphenol A in microplastics includes:

[0027] The microplastic extract, the ITO electrode, the saturated calomel reference electrode and the platinum counter electrode are placed in a K2SO4 electrolyte, illuminated with a light, and the degradation solution is collected;

[0028] Determining the concentration C of bisphenol A in the degradation solution;

[0029] The degradation rate K of bisphenol A was obtained by the formula degradation rate K (%) = (C0–C) / C0 × 100%; where C0 is the initial concentration of bisphenol A.

[0030] Specifically, before turning on the light for irradiation, the process also includes:

[0031] The electrode is immersed in the K2SO4 electrolyte in a dark environment to react for 10-40 minutes.

[0032] Specifically, the step of turning on the light to irradiate and collecting the degradation liquid comprises:

[0033] The xenon lamp was turned on for irradiation, and the degradation liquid was collected every 30 minutes for a total of 150 minutes.

[0034] One or more technical solutions provided in the present invention have at least the following technical effects or advantages:

[0035] (1) A CoO / SCS composite material with photoelectric activity is constructed, and a PEC sensor is constructed based on the CoO / SCS material. Bisphenol A released from microplastics is used as the target for PEC detection. The PEC process converts light energy into electrical energy and chemical energy, reducing the dependence on bias voltage, thereby improving the precision of detection. The present invention combines the advantages of optical and electrochemical methods, and has the advantages of simple operation, rapid response, and high sensitivity.

[0036] (2) The composite material CoO / SCS was synthesized. This material has a Z-type heterostructure, which can expand the visible light absorption range, accelerate the separation and transfer of photogenerated carriers, and improve the detection sensitivity and catalytic activity. The holes generated by the photocathode electrode based on CoO / SCS are transmitted to the external circuit before being oxidized, which can avoid the photocathode photooxidation phenomenon, thus having strong anti-interference ability and better stability. The detection based on the redox of the target itself has better stability and a wide linear range.

[0037] (3) During the detection process, electron holes undergo redox reactions to generate reactive oxygen species, which can further react with bisphenol A to achieve the removal of the target substance, effectively reducing or eliminating the concentration of bisphenol A in the environment and reducing the potential impact on the ecosystem, food safety and human health. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A flow chart of a method for preparing a photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics provided in an embodiment of the present invention;

[0039] Figure 2 This is the XRD characterization diagram of the CoO / SCS material in the embodiment of the present invention;

[0040] Figure 3 These are SEM images of the present invention; wherein (a) is CoO (1 μm), (b) is SCS (1 μm), and (c) is CoO / SCS (1 μm);

[0041] Figure 4(a) is the transient photocurrent response diagram of CoO, SCS, and CoO / SCS. Figure 4 (b) EIS graphs of CoO, SCS, and CoO / SCS;

[0042] Figure 5 (a) is the calibration curve of CoO / SCS-based PEC sensor at different BPA concentrations. Figure 5 (b) Photocurrent response of CoO / SCS-based PEC sensor at different BPA concentrations;

[0043] Figure 6 (a) is the degradation efficiency based on CoO, SCS, and CoO / SCS photoelectrodes. Figure 6 (b) is the degradation efficiency based on PEC, PC, and EC processes. Figure 6 (c) is the degradation efficiency at initial concentrations of 5 mg / L, 10 mg / L, and 15 mg / L. Figure 6 (d) is the first-order kinetic curve of the degradation process of CoO, SCS, and CoO / SCS photoelectrodes. Figure 6 (e) is the first-order kinetic curve based on the degradation process of PEC, PC, and EC. Figure 6 (f) is the first-order kinetic curve of the degradation process at initial concentrations of 5 mg / L, 10 mg / L, and 15 mg / L;

[0044] Figure 7 is the photoelectric degradation stability diagram;

[0045] Figure 8 (a) is the photoelectric degradation mechanism diagram. Figure 8 (b) Possible pathways for photoelectrochemical degradation of BPA. DETAILED DESCRIPTION

[0046] The embodiment of the present invention achieves the technical effect of high-precision and high-sensitivity detection and degradation of BPA by providing a photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics and its preparation and application.

[0047] The technical solution in the embodiment of the present invention is to achieve the above technical effects, and the overall idea is as follows:

[0048] The synthesis of CoO / SCS composite materials is as follows:

[0049] 1) Preparation of CoO. Co(NO3)2·6H2O (2-3 g), NH4F (1-2 g) and CO(NH2)2·3-4 g) were mixed in 50 ml of ethylene glycol and stirred for 5-10 minutes, and then the solution was placed in an autoclave (100 ml) and reacted at 90-100°C for 6-8 hours. The obtained sample was washed three times with deionized water and ethanol respectively. It was dried under vacuum conditions at 60-80°C for 6-10 hours to obtain CoO.

[0050] 2) Preparation of X-CoO / SCS, X = m(CoO) / m(SnCoS4) = 3%, 9%, 15%. CoO, CoCl2·6H2O (0.13 g), SnCl4·5H2O (0.20 g), and L-cysteine ​​(0.34 g) were dispersed in 60 mL of deionized water by ultrasound for 10-20 min, stirred for 30 min to obtain a uniform suspension, and then reacted in an autoclave (100 mL) at 160-180°C for 10-14 h. The resulting X-CoO / SCS was washed with deionized water and ethanol, and then dried at 60°C.

[0051] PEC sensor experiment: CoO / SCS composite material was dispersed into 200 μL of ethanol and 300 μL of chitosan solution (CS, 0.5% w / v) by ultrasound. 20 μL of CoO / SCS suspension was directly dropped on the surface of ITO electrode (1.0 cm 2 ), and then dried. A three-electrode system consisting of an ITO working electrode, a platinum wire counter electrode, and a saturated calomel reference electrode was established for electrochemical characterization using a CHI 660E workstation (light source: 300 W xenon lamp, applied voltage: -0.2 V). Photoelectric tests of PEC sensing were carried out in 0.1 M K2SO4 with a lamp on / off time of 20 s. Electrochemical impedance spectroscopy (EIS) was performed in a solution containing 2.5 mM [Fe(CN)6] 3- / 4- All PEC experiments were performed at room temperature.

[0052] The photoelectrocatalytic degradation experiment of BPA was carried out in a three-electrode system on a CHI 660E electrochemical workstation. The three-electrode system consisted of an ITO working electrode modified with 100 μL CoO / SCS material (100 μL CoO / SCS suspension, 4 cm 2 )、Pt counter electrode(2 cm 2) and a saturated calomel reference electrode. The electrolyte is 0.1 M K2SO4, which contains different concentrations of bisphenol A (5, 10, 15 µg / mL), and the working volume is 100 mL. The distance between the light source and the electrode is kept at 10 cm. Before the degradation experiment officially begins, the photoelectrode needs to react for 15 minutes under dark conditions to reach adsorption-desorption equilibrium, and then turn on the light for irradiation. Specifically, with the xenon lamp turned on, the degradation solution is collected every 30 minutes of irradiation, and the total illumination time is 150 minutes. Then the degradation solution is passed through the membrane and the concentration of BPA is determined by high performance liquid chromatography, and the concentration at this time is recorded as C. Degradation rate K (%) = (C0– C) / C0× 100%, C0 is the initial concentration of BPA.

[0053] In summary, the embodiments of the present invention have developed a Z-scheme heterostructure of a CoO / SCS composite material with dual functions of detection and degradation, and constructed a PEC sensor and catalytic system based on the CoO / SCS composite material. Bisphenol A, a microplastic eluting substance, is used as the target, and sensitive detection and efficient degradation of bisphenol A are achieved, providing a feasible approach for environmental monitoring and food safety.

[0054] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0055] See also Figure 1 The method for preparing a photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics provided by an embodiment of the present invention comprises:

[0056] Step S110: Mix Co(NO3)2·6H2O, NH4F and CO(NH2)2 in ethylene glycol to obtain a mixed solution;

[0057] Step S120: placing the mixed solution into a high pressure reactor and reacting at 90-100° C. for 6-8 hours;

[0058] Specifically, the mixed solution is placed in a high pressure reactor and reacted at 90-100° C. for 6-8 hours, comprising:

[0059] The mixed solution was placed in a polytetrafluoroethylene autoclave and reacted at 95°C for 6 hours.

[0060] Step S130: drying the reacted solution under vacuum conditions at 60-80° C. for 6-10 hours to obtain CoO;

[0061] Step S140: dispersing CoO, CoCl2·6H2O, SnCl4·5H2O and L-cysteine ​​in deionized water to obtain a suspension;

[0062] Specifically, this step is described as follows: CoO, CoCl2·6H2O, SnCl4·5H2O and L-cysteine ​​are dispersed in deionized water to obtain a suspension, comprising:

[0063] CoO, CoCl2·6H2O, SnCl4·5H2O and L-cysteine ​​were added to deionized water, dispersed by ultrasonication for 10 minutes, and stirred for 20 minutes to obtain a suspension.

[0064] Step S150: reacting the suspension in a high pressure reactor at 160-180° C. for 10-14 hours to generate a CoO / SCS composite material;

[0065] In order to obtain a purer composite material and thus improve the detection accuracy, after the CoO / SCS composite material is generated, the following steps are also included:

[0066] The CoO / SCS composites were washed alternately with deionized water and ethanol and then dried under vacuum at 60 °C for 10 h.

[0067] Step S160: After dispersing the CoO / SCS composite material into a mixed solution of ethanol and water solution, the mixed solution is drop-coated on the surface of the ITO electrode.

[0068] An embodiment of the present invention also provides a photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics, which is prepared by the above method.

[0069] The crystal structure of CoO / SCS was characterized by XRD. Figure 2 In the figure, the peaks corresponding to the (111), (200), (220), (311) and (222) planes of CoO are located at 36.5°, 42.4°, 61.5°, 73.7° and 77.5°, proving that CoO was successfully synthesized. Figure 2 As shown, the XRD spectra of X-CoO / SCS and SCS Figure 1 The XRD spectrum of CoO / SCS shows weak diffraction peaks at 32.1°, 39.8°, 41.8, 54.9°, 60.6° and 64.9°. The absence of CoO characteristic peaks in the XRD spectrum of CoO / SCS may be due to the low content of CoO. In addition, the diffraction peaks of SCS at 32.1°, 39.8°, 41.8, 54.9° and 60.6° correspond to the (101), (211), (102), (311) and (201) crystal planes of SnS2 and CoS2, but the diffraction peaks at 37.8° and 64.9° do not correspond to the crystal planes of SnS2 and CoS2, which indicates that SCS is not a simple mixture of SnS2 and CoS2, proving the successful synthesis of the composite material CoO / SCS.

[0070] The morphology and structure of CoO, SCS and CoO / SCS were characterized by various imaging techniques. First, SEM showed that CoO was a nanosphere with a large surface area ( Figure 3 a). SCS is a nanoflower structure ( Figure 3 b). CoO was introduced by solvothermal method at 180 °C for 12 h to form CoO / SCS composite material ( Figure 3 c). The morphology of CoO was destroyed under high temperature, forming nanoparticles that were evenly attached to the surface of the SCS nanoflower petals, indicating that the CoO / SCS material was successfully synthesized.

[0071] The carrier separation efficiency and charge transfer characteristics of the CoO / SCS heterojunction were further investigated by photocurrent testing and electrochemical impedance spectroscopy. Figure 4 a and Figure 4 b are the photocurrent response spectra and EIS spectra of CoO, SCS and CoO / SCS, respectively. As shown in the figure, the electrode modified with CoO / SCS has the largest photocurrent (ΔI, -2.53 μA), indicating that CoO / SCS effectively reduces the recombination of photogenerated electron-hole pairs. In addition, the ΔI of CoO and SCS are -0.07 and -0.52 μA, respectively. In addition, the EI test results show that the resistance value of electron transfer on the electrochemical impedance curve of CoO / SCS is the smallest, which is 3.88 Ω ( Figure 4 b). In addition, the resistance values ​​of CoO and SCS are 7.50 and 6.65 Ω, respectively. These results show that CoO / SCS has better PEC properties and can produce more active substances through redox reactions. This means that CoO / SCS has efficient photoelectrocatalytic performance.

[0072] The embodiments of the present invention also provide the application of a photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics, including: detecting the content of bisphenol A in microplastics or degrading bisphenol A in microplastics.

[0073] In this example, the evaluation of the CoO / SCS-based BPA detection PEC sensor is as follows:

[0074] Under optimal conditions, the present invention established a CoO / SCS-based PEC sensor for detecting BPA. The photocurrent-time test found that the BPA concentration (C BPA ) and the photocurrent change (ΔI) show a satisfactory linear relationship ( Figure 5 a), the linear fitting equation is ΔI = - 0.33 × lgC BPA -5.30 (R 2=0.995). By testing 21 sets of blank sample values, the LOD of the PEC sensor was calculated to be 0.56 pg / mL. By comparison, it was found that the LOD value was 11-3257 times that reported previously (Table 1). The CoO / SCS-based PEC sensor has a higher sensitivity for BPA detection. The photocurrent response to different concentrations of BPA (A→M: 0.00228, 0.0057, 0.0114, 0.0228, 0.057, 0.114, 0.57, 2.28, 11.4, 45.6, 228, 1140, 4560 ng / mL) was further tested, and the ΔI when different concentrations of BPA were added was recorded. It can be seen that with the increase in BPA concentration, the size of ΔI also increases ( Figure 5 b).

[0075] Table 1 Comparison of BPA detection results by different methods

[0076]

[0077] Specifically, the content of bisphenol A in microplastics is detected, including:

[0078] The microplastic extract, ITO electrode, saturated calomel reference electrode and platinum counter electrode were placed in K2SO4 electrolyte, illuminated with light, and IT test was performed to obtain the photocurrent data ΔI;

[0079] Substitute the photocurrent data ΔI into the linear fitting equation ΔI=-0.33×lgC BPA -5.30 Calculate the concentration of bisphenol A in the sample C BPA .

[0080] Degradation of bisphenol A in microplastics, including:

[0081] The microplastic extract, ITO electrode, saturated calomel reference electrode and platinum counter electrode were placed in K2SO4 electrolyte, illuminated with light, and the degradation solution was collected;

[0082] Determine the concentration C of bisphenol A in the degradation solution;

[0083] Specifically, the concentration C of bisphenol A in the degradation solution is determined, including:

[0084] The concentration of bisphenol A in the degradation solution was analyzed by high performance liquid chromatography (C);

[0085] In this embodiment, the parameters of the HPLC are as follows: the mobile phase is a mixture of methanol and water (70 / 30, v / v). The flow rate is set to 1.0 mL / min, and the column temperature is set to 35°C. The injection volume is 10 µL, the fluorescence excitation wavelength is 228 nm, and the emission wavelength is 312 nm.

[0086] The degradation rate K of bisphenol A was obtained by the formula degradation rate K (%) = (C0–C) / C0 × 100%; where C0 is the initial concentration of bisphenol A.

[0087] In order to achieve adsorption-desorption equilibrium, before turning on the light, it also includes:

[0088] The electrode was immersed in K2SO4 electrolyte in a dark environment for 10-40 minutes.

[0089] In this embodiment, turning on the light to irradiate and collecting the degradation liquid includes:

[0090] The xenon lamp was turned on for irradiation, and the degradation liquid was collected every 30 minutes for irradiation, and the irradiation time was 150 minutes in total. In this embodiment, a 300W xenon lamp was used as the light source, and the applied voltage was set to -0.2V.

[0091] Example 1

[0092] The embodiment of the present invention provides a photoelectrochemical sensor of bisphenol A in microplastics based on CoO / SnCoS4 nanomaterials and its preparation and application. The preparation method comprises the following steps:

[0093] (1) Preparation of CoO / SnCoS4 composite materials:

[0094] First, Co(NO3)2·6H2O (2.91 g), NH4F (1.48 g) and CO(NH2)2 (3.00 g) were mixed in 50 mL of ethylene glycol and stirred for 5 minutes to obtain a clear mixed solution. The solution was then poured into a polytetrafluoroethylene autoclave and reacted at 95°C for 6 hours. After cooling, the sample was washed alternately with deionized water and ethanol three times. Then, CoO was obtained by vacuum drying at 60°C for 8 hours. Next, a composite material CoO / SCS was prepared, in which m(CoO) / m(SnCoS4) = 9%. CoO, CoCl2·6H2O (0.13 g), SnCl4·5H2O (0.20 g) and L-cysteine ​​(0.34 g) were added to 60 mL of deionized water, dispersed by ultrasonication for 10 minutes, and then stirred for 20 minutes to obtain a uniform suspension. The suspension was transferred into a 100 mL polytetrafluoroethylene autoclave and heated to 180°C for 12 hours to complete the reaction. The generated CoO / SCS was washed alternately with deionized water and ethanol three times, and then vacuum dried at 60°C for 10 hours.

[0095] (2) Pretreatment of ITO electrode: Ultrapure water, anhydrous ethanol, and ultrapure water were ultrasonically cleaned for 10 minutes in turn, and finally dried naturally.

[0096] (3) Construction of photoelectric sensor based on CoO / SnCoS4 material:

[0097] Weigh CoO / SCS (5 mg) and disperse it in a mixed solution of 200 μL ethanol and 300 μL CS aqueous solution (0.5% w / v). Ultrasonicate for 12 minutes to ensure uniform dispersion. Then use a pipette to accurately take 20 μL of CoO / SCS dispersion and directly drop it on the cleaned ITO electrode surface (0.5 cm 2 ), and let dry naturally.

[0098] (4) Detection principle of CoO / SnCoS4 composite photoelectric sensor:

[0099] A three-electrode system consisting of an ITO electrode, a platinum electrode, and SCE was established using a CHI 660E workstation (light source: 300 W xenon lamp, external voltage: -0.2 V) for photocurrent-time measurement and electrochemical impedance spectroscopy (EIS) in a 0.1 M K2SO4 electrolyte. 3- / 4- All PEC experiments were performed at room temperature.

[0100] (5) Detection of bisphenol A in polycarbonate plastic milk bottles, plastic barrels of soybean oil, and textiles:

[0101] (a) Sample pretreatment:

[0102] Polycarbonate plastic milk bottle: Cut the plastic container into pieces of about 0.1 cm, accurately weigh 0.4949 g of the pieces and place them in 3 mL of acetonitrile, heat and extract at 40°C for 4 hours. Transfer 2 mL through a 0.22 um organic filter membrane for testing.

[0103] Pretreatment of plastic barrel soybean oil samples: Use solid phase extraction columns to purify the samples. Activate the solid phase extraction column with 10 mL of n-hexane, 10 mL of dichloromethane, 10 mL of methanol, and 10 mL of ultrapure water in sequence. Add 6 mL of soybean oil sample diluted with n-hexane to the column, and flush impurities with 6 mL of methanol. Then elute the extraction column with 8 mL of dichloromethane and collect the eluate in a concentration bottle. Blow dry the eluate with N2 and then add 6 mL of acetonitrile to dissolve it. Pass the dissolved solution through a membrane for later use.

[0104] Pretreatment of textile samples: Weigh 1.0 g of clothing (textiles), cut it into pieces and put it into a glass bottle, then add 30 mL of methanol to the glass bottle and ultrasonicate at 35°C for 30 minutes. Finally, filter the sample solution through a polytetrafluoroethylene filter membrane before use.

[0105] (b) Detection:

[0106] (1) Add the sample extracts of textiles, polycarbonate plastic milk bottles, and soybean oil into 0.1M K2SO4 electrolyte, and place the ITO working electrode modified with CoO / SnCoS4 nanomaterials into the electrolytic cell (the reference electrode is SCE and the counter electrode is a platinum electrode). Perform an IT test by turning on the light at -0.2 V for 20 seconds and turning off the light for 20 seconds to obtain the photocurrent data, and then use it to calculate the concentration in the sample.

[0107] The accuracy of the PEC sensor was verified by comparing the BPA concentration obtained by the PEC sensor under actual samples with the BPA concentration obtained by HPLC (national standard method). Two different concentrations of BPA (0.2 and 60 ng / mL) were added to blank polycarbonate plastic bottles, soybean oil and textile samples, and the recoveries of the PEC sensor were 102.27%-115%, 80%-103.70% and 85%-101.55%, respectively, with RSDs of 1.75%-4.54% (Table 2). The results show that the accuracy of the CoO / SCS-based PEC sensor in determining BPA in actual complex samples is satisfactory, and it can be applied to BPA detection in environmental monitoring and food safety.

[0108] Table 2 Comparison of the results of photoelectric sensor and HPLC in detecting BPA in actual samples

[0109]

[0110] Example 2

[0111] This embodiment provides an application of CoO / SnCoS4 nanomaterials for photoelectrocatalytic degradation of bisphenol A. The preparation method comprises the following steps:

[0112] (1) Preparation of CoO / SnCoS4 composite material: The preparation method of the nanomaterial is the same as that in Example 1.

[0113] (2) Photoelectrocatalytic degradation

[0114] Degradation experimental conditions: The photoelectrochemical degradation experiment of bisphenol A (BPA) was also completed using a three-electrode system of a CHI 660E electrochemical workstation. The three-electrode system consisted of an ITO working electrode (4 cm2) modified with 100 μL CoO / SCS material. 2 ), platinum sheet by the counter electrode (2 cm 2) and SCE. The electrolyte is 0.1 M K2SO4, the working volume is 100 mL, and the distance between the light source and the electrode is kept at 10 cm. Before the degradation experiment officially begins, the photoelectrode needs to react in dark conditions for 15 minutes to reach adsorption-desorption equilibrium, and then turn on the light for irradiation. The degradation liquid is collected once every 30 minutes of illumination, and the total illumination time is 150 minutes. After the degradation liquid passes through the membrane, the concentration of BPA is determined by high performance liquid chromatography, and the concentration at this time is recorded as C. Degradation rate K (%) = (C0– C) / C0× 100%, C0 is the initial concentration of BPA.

[0115] (3) Study on photoelectrocatalytic degradation performance

[0116] The photocatalytic degradation of BPA based on CoO / SCS cathode material in a three-electrode system was investigated. First, the photocatalytic degradation efficiency of CoO, SCS and CoO / SCS was compared. The photocatalytic reaction was carried out in 100 mL K2SO4 electrolyte for 150 minutes. Figure 6 As shown in a, the degradation efficiency of CoO / SCS (72.66%) is higher than that of CoO (23.58%) and SCS (36.85%). The kinetics of the process was also calculated, and the kinetic curve calculation formula is: -ln(C / C0) = kt (k: degradation rate constant, t: time). Figure 6 d, the rate constant k of CoO / SCS is 0.009 min -1 , respectively CoO (k = 0.002 min -1 ) and SCS (k = 0.003 min -1 ) by 4.50 and 3.00 times, and the magnitude relationship of the degradation efficiency is consistent with the results of the pseudo-first-order kinetic curve. Therefore, the formation of the heterojunction can reduce the recombination of electron-hole pairs and produce more ·OH and ·O 2- , thereby accelerating the degradation of BPA. Then, the degradation efficiency of BPA in the PEC, EC and PC processes was further explored using the CoO / SCS photocathode with the best degradation efficiency. Figure 6 b and Figure 6 As shown in Figure e, after 150 minutes of reaction, the BPA degradation efficiency of PEC was 3.5 times and 2.4 times that of EC (20.94%) and PC (31.97%), respectively. PEC had the best degradation efficiency, which was consistent with the results of the pseudo-first-order kinetic curve. The initial concentration of BPA also had a significant effect on the degradation efficiency. Therefore, this example explored the photoelectric degradation efficiency of BPA based on CoO / SCS photocathode at different initial concentrations ( Figure 6 c and Figure 6f). The concentration of BPA was set to 5 mg / L, 10 mg / L, and 15 mg / L. When the BPA concentration increased from 5 mg / L to 15 mg / L, the photoelectrochemical degradation efficiency decreased from 75.28% to 53.43%. Due to the limited active sites on the CoO / SCS surface, many target molecules could not be rapidly degraded as the BPA concentration increased. Therefore, an initial concentration of 5 mg / L of BPA was selected for subsequent experiments. Figure 7 As shown, after six photoelectrocatalytic experiments, the degradation efficiency of BPA dropped from 75.28% to 73.67%, and the removal effect of BPA was good, which proved that the CoO / SCS photoelectrocatalysis provided by the embodiment of the present invention had good stability.

[0117] (4) Degradation pathway

[0118] The above experiments and test results show that the mechanism of degradation of BPA is as follows:

[0119] CoO / SCS+ hv→CoO / SCS (h + + e − ) (1)

[0120] O2+ e − → O2 − (2)

[0121] O2 − + e − + 2H + →H2O2 (3)

[0122] H2O2+ e − → OH (4)

[0123] BPA + h + + ·O2 − + ·OH→degradation product (5)

[0124] Under light irradiation, the CoO / SCS composite material is excited to generate electron-hole pairs (h + / e − ), h + It has strong oxidizing properties, - It has strong reducing properties. Since CoO / SCS forms a Z-type heterojunction, electrons are transferred from the CB of CoO to the VB of SCS. At the same time, the applied external voltage accelerates the h + and e − Separation of SCS CB Greater than O2 / ·O 2- The potential of the heterostructure is -0.33 eV, so the electrons in the CB react with O2 to produce a large amount of ·O2- , BPA will be 2- Direct oxidation. The VB of CoO is less than the potential of ·OH / H2O (2.27 eV), which indicates that ·OH mainly comes from e − Induced multi-step reduction, rather than h + Oxidation. The above analysis is consistent with the ESR test results. BPA molecules will be subjected to ·O 2- , OH and h + The degradation pathway is shown in Figure 8 a. BPA (C 15 H 16 O2, m / z=227) and chemical structure information of degradation intermediates. 10 (m / z=117)、C9H 12 O (m / z=133), C9H 10 O (m / z=135), C 14 H 18 O5 (m / z = 265) and C 14 H 21 O6 (m / z = 283), such as Figure 8 This degradation pathway confirms that the CoO / SCS Z-type heterojunction proposed in this example has good degradation efficiency.

[0125] In summary, the flower-like CoO / SnCoS4 nanomaterials were successfully designed and prepared in the embodiment of the present invention, and the material was successfully applied to the PEC system. The CoO / SCS-based PEC sensor was successfully constructed, which achieved sensitive detection and efficient degradation of BPA. With CoO / SCS as the photocathode, the PEC sensor can detect BPA in complex environments and food samples (plastic bottles, soybean oil and textiles). Under optimal conditions, the CoO / SCS-based PEC sensor has wide linearity (0.00228-4560 ng / mL) and high sensitivity (LOD: 0.56 pg / mL) for the detection of BPA, while the repeatability (RSD of 4.00%), reproducibility (RSD of 4.10%) and selectivity are satisfactory. In addition, the degradation efficiency of CoO / SCS photocathode for BPA with an initial concentration of 5 mg / mL within 150 minutes is 75.28%. ESR shows that·O 2- and ·OH are the main active substances, and h + 、e − Therefore, CoO / SCS has convincing dual functions in PEC sensing and degradation of BPA, providing a feasible way to control microplastics in the environment and food.

[0126] The parts not described in detail in the embodiments of the present invention are all known technologies to those skilled in the art. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics, characterized in that: include: Co(NO3)2·6H2O, NH4F and CO(NH2)2 are mixed in ethylene glycol to obtain a mixed solution; The mixed solution was placed in a high pressure reactor and reacted at 90-100° C. for 6-8 hours; The reacted solution is dried under vacuum conditions at 60-80° C. for 6-10 hours to obtain CoO; Dispersing the CoO, CoCl2·6H2O, SnCl4·5H2O and L-cysteine ​​in deionized water to obtain a suspension; The suspension is reacted in a high pressure reactor at 160-180° C. for 10-14 hours to generate a CoO / SnCoS4 composite material; After the CoO / SnCoS4 composite material is dispersed in a mixed solution of ethanol and aqueous solution, it is drop-coated on the surface of the ITO electrode.

2. The method for preparing the photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics according to claim 1, characterized in that: The mixed solution was placed in a polytetrafluoroethylene autoclave and reacted at 95° C. for 6 hours.

3. The method for preparing the photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics according to claim 1, characterized in that: The CoO, CoCl2·6H2O, SnCl4·5H2O and L-cysteine ​​are added into deionized water, dispersed by ultrasonication for 10 minutes, and stirred for 20 minutes to obtain the suspension.

4. The method for preparing the photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics according to claim 1, characterized in that: After the CoO / SnCoS4 composite material was generated, the CoO / SnCoS4 composite material was washed alternately with deionized water and ethanol, and then vacuum dried at 60°C for 10 hours.

5. A photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics prepared according to the method described in any one of claims 1 to 4.

6. The use of the photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics as claimed in claim 5, characterized in that: include: Detect the content of bisphenol A in microplastics or degrade bisphenol A in microplastics.

7. The use of the photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics as claimed in claim 6, characterized in that: The detection of the content of bisphenol A in microplastics comprises: The microplastic extract, the ITO electrode, the saturated calomel reference electrode and the platinum counter electrode are placed in a K2SO4 electrolyte, illuminated by light, and an IT test is performed to obtain photocurrent data ΔI; Substitute the photocurrent data ΔI into the linear fitting equation ΔI=-0.33×lgC BPA -5.30 Calculate the concentration of bisphenol A in the sample C BPA .

8. The use of the photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics as claimed in claim 6, characterized in that: The method of degrading bisphenol A in microplastics comprises: The microplastic extract, the ITO electrode, the saturated calomel reference electrode and the platinum counter electrode are placed in a K2SO4 electrolyte, illuminated with a light, and the degradation solution is collected; Determining the concentration C of bisphenol A in the degradation solution; The degradation rate K of bisphenol A was obtained by the formula: degradation rate K (%) = (C0–C) / C0 × 100%; where C0 is the initial concentration of bisphenol A.

9. The use of the photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics as claimed in claim 8, characterized in that: Before turning on the light for irradiation, the electrode is immersed in the K2SO4 electrolyte in a dark environment for reaction for 10-40 minutes.

10. The use of the photoelectrochemical sensor for detecting and degrading bisphenol A in microplastics as claimed in claim 8, characterized in that: The step of turning on the light for irradiation and collecting the degradation liquid specifically includes: turning on the xenon lamp for irradiation and collecting the degradation liquid every 30 minutes of irradiation, for a total of 150 minutes of irradiation.

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