Photoelectrocatalytic degradation method for patulin in fruit matrix

Abstract

The invention provides a photoelectrocatalytic degradation method for patulin in apple juice, which comprises the following steps: growing TiO2 on the surface of a fluorine-doped tin oxide conductive glass electrode treated by plasma, and annealing to obtain a TiO2 nanorod electrode; the preparation method comprises the following steps: growing a silicon dioxide film with the thickness of 10-40nm on the surface of a TiO2 nanorod electrode by a # imgabs0 # solution growth method, and after annealing, cleaning redundant # imgabs1 # solution to obtain a TiO2 nanorod electrode modified by a vertical pore silicon dioxide film; the TiO2 nanorod electrode is inserted into apple juice and serves as a working electrode, a platinum electrode serves as a counter electrode, an Ag / AgCl electrode serves as a reference electrode, and patulin of the apple juice is degraded through photoelectrocatalysis under irradiation of a light source. According to the TiO2 nanorod electrode prepared by the method, stable, accurate and efficient degradation of patulin can be realized while nutrient components rich in apple juice are not influenced.

Description

Technical Field

[0001] The invention belongs to the field of food safety control, and particularly relates to a photoelectrocatalytic degradation method of patulin in a fruit matrix. Background Art

[0002] Patulin is a toxic metabolite produced by molds, with potential carcinogenicity, immunotoxicity, and neurotoxicity. Long-term ingestion can cause serious harm to human health. Furthermore, WHO data shows that global medical expenses due to health problems caused by mycotoxins exceed tens of billions of US dollars annually. Furthermore, data from the National Food Safety Risk Assessment Center shows that the annual rejection rate of apple juice in my country due to mold contamination is approximately 5%-10%, with direct economic losses from export returns and destruction reaching hundreds of millions of RMB, resulting in significant economic losses in my country. Developing efficient technologies to degrade patulin in apple juice is crucial for food safety and public health.

[0003] Currently, the main methods for degrading patulin include physical, chemical, and biological methods. However, each of these three degradation methods has its own advantages and disadvantages. Physical methods are suitable for batch processing, but they often have low selectivity, limited adsorption capacity, difficult separation, and high equipment requirements that can lead to secondary food contamination. Chemical treatment methods are simple to operate and low in cost, but they also have high equipment costs and unclear safety results. Although biological treatment technology has good biocompatibility, it faces limitations in practical applications, such as the difficulty in strain selection and poor environmental adaptability. Furthermore, this method often has difficulty in completely decomposing the toxin molecules and can only convert them into less toxic derivatives, making it difficult to meet the requirements of large-scale production. Therefore, there is an urgent need to develop a green, environmentally friendly, simple, and efficient technology for degrading patulin in apple juice.

[0004] Photoelectrocatalytic technology combines the advantages of photocatalysis and electrocatalysis. It offers advantages such as mild operating conditions, the ability to utilize sunlight, wide applicability, and the absence of secondary pollution. This technology has the potential to efficiently degrade patulin in apple juice. However, the application of photoelectrocatalytic technology in complex food matrices faces the following key challenges. First, photoelectrocatalytic nanomaterials are key to this technology. However, these materials on photoelectrodes are prone to severe instability during long-term operation, including shedding, aggregation, dissolution, and photocorrosion. This not only reduces the catalytic activity of the photoelectrode but also introduces secondary contamination to the food. Second, photoelectrocatalytic degradation relies on highly oxidative reactive oxygen species (ROS). However, ROS are non-selective and, while degrading pollutants, can also destroy nutrients rich in the food matrix. This significantly limits the widespread application of photoelectrocatalytic technology in complex food matrices. Therefore, addressing the stability and selectivity issues of photoelectrocatalytic nanomaterials can ensure efficient, stable, and precise degradation of patulin without affecting the nutrients rich in the food matrix, thereby promoting the widespread application of photoelectrocatalytic technology in food safety.

[0005] The cells in the body are covered by an ultra-thin cell membrane (5-10nm), which not only maintains the stability of the cell structure, but also promotes ultra-fast exchange and precise regulation of molecules inside and outside the cell. Specifically, the cell membrane ensures the relative stability of the intracellular environment; and these ultra-small biological channels on the cell membrane (ranging from 0.5-3nm) achieve selective permeability of specific ions and molecules through specific molecular recognition, and promote ultra-fast exchange of molecules inside and outside the cell, ensuring that the cell can still maintain its function in a complex environment. It is reported that nanochannels and ultra-small pores are essential for ultra-fast material transport and biochemical reactions. Therefore, similar to the cell membrane, we assume that the ultra-thin silica film with ultra-small vertical nanochannels can significantly improve the stability of the photoelectrode in long-term operation without affecting the photoelectrocatalytic performance, avoiding the instability problems such as photocorrosion, agglomeration or shedding that are prone to occur in traditional photoelectrodes; in addition, the structure of the ultra-thin film and ultra-small vertical channels will effectively give the electrode excellent selectivity, thereby realizing efficient, precise and sustainable food safety control applications. Summary of the Invention

[0006] The present invention provides a photoelectrocatalytic degradation method for patulin in a fruit matrix. The TiO2 nanorod electrode prepared by the photoelectrocatalytic method can achieve stable, accurate and efficient degradation of patulin without affecting the nutrients rich in the fruit matrix.

[0007] The present invention provides a photoelectrocatalytic degradation method for patulin in an apple fruit matrix, comprising:

[0008] Step 1: growing TiO2 on the surface of a plasma-treated fluorine-doped tin oxide conductive glass electrode, and annealing to obtain a TiO2 nanorod electrode;

[0009] Step 2: Pass Solution growth method, growing a silicon dioxide film with a thickness of 15–40 nm on the surface of the TiO2 nanorod electrode, and then cleaning the excess after annealing. The solution obtained a TiO2 nanorod electrode modified with a vertical pore silica film;

[0010] Step 3: insert the TiO2 nanorod electrode into the fruit juice and use it as a working electrode, a platinum electrode as a counter electrode, and an Ag / AgCl electrode as a reference electrode. Under light illumination, the patulin in the fruit juice is degraded by photoelectrocatalysis.

[0011] The present invention utilizes the negative charge of the silica membrane to repel negatively charged nutrients in fruit juice, and utilizes its mesopore size to prevent the entry of large-sized nutrients. At the same time, the present invention utilizes the peculiar adsorption energy of the pores to more easily adsorb patulin with C=O than glucose and fructose. Therefore, the present invention utilizes the silica membrane to more easily allow patulin to enter, while other nutrients have difficulty entering the silica membrane.

[0012] The present invention also provides a silicon dioxide film of suitable thickness, so that the reactive oxygen species (ROS) generated by the TiO2 nanorods degrade patulin in the pores of the silicon dioxide film and are difficult to escape from the silicon dioxide film, thereby preventing the ROS from degrading other nutrients in the fruit juice and preventing the degradation of patulin due to excessive thickness.

[0013] Preferably, the plasma treatment time is 0-2 min, excluding 0 min.

[0014] Preferably, the method for preparing the TiO2 nanorod electrode comprises:

[0015] Tetrabutyl titanate was added dropwise to a mixed solution of deionized water and 36-38 wt% hydrochloric acid;

[0016] The solution was stirred continuously until it became transparent and then transferred to a Teflon-lined stainless steel autoclave;

[0017] The fluorine-doped tin oxide conductive glass obtained in step 1 is placed in an autoclave, and the polytetrafluoroethylene container wall is maintained at 30-45 degrees for growth.

[0018] Further preferably, the volume of the mixed solution is 10-30 mL, and in the mixed solution, the volume ratio of the deionized water to the hydrochloric acid is 0.5-2.

[0019] More preferably, the volume of tetrabutyl titanate is 20-100 μL.

[0020] More preferably, the growth temperature is 150° C. and the growth time is 12 h.

[0021] Preferably, in step 1, the annealing temperature is 400-600° C., and the annealing time is 1-5 hours.

[0022] Preferably, the The solution growth method involves mixing hexadecyltrimethylammonium bromide, deionized water, ethanol, ammonia, and tetraethoxysilane in a beaker and stirring. Subsequently, a TiO2 nanorod electrode is immersed in the solution to grow silica. In an alkaline electrolyte, the surface of the TiO2 nanorod electrode becomes negatively charged due to surface hydroxylation. Hexadecyltrimethylammonium bromide cations adsorb on the negatively charged electrode through electrostatic interactions, forming spherical micelles. Simultaneously, the silica precursor tetraethoxysilane hydrolyzes to form positively charged oligomeric silicates, which adsorb around the hexadecyltrimethylammonium bromide. As a result, a silica film grows vertically on the metal oxide surface. The surfactant is removed by solvent extraction to obtain an ultrathin silica nanochannel coating. Furthermore, by effectively controlling the growth time, the thickness of the silica film at the TiO2 nanorod electrode interface can be controllably adjusted.

[0023] Further preferably, the mass of the hexadecyltrimethylammonium bromide is 0.1-0.2 g; the volume of the deionized water is 50-80 mL; the volume of the ethanol is 20-50 mL; the concentration of the ammonia water is 2.5-2.8%, and the volume is 50-200 μL; the volume of the tetraethoxysilane is 50-100 μL; the growth temperature of the silica is 50-70°C, and the growth time is 5-16 h.

[0024] Preferably, in step 2, the annealing temperature is 80-120° C., and the annealing time is 12-36 hours.

[0025] Preferably, the excess The concentration of the hydrochloric acid ethanol solution is 0.05-0.1 mol / L, and the elution time is 10-15 min.

[0026] Preferably, the device for photoelectrocatalytic degradation of patulin in fruit juice is a CHI660E electrochemical workstation.

[0027] Preferably, a 300W xenon lamp equipped with a 365nm filter is used for light irradiation, with a light intensity of 5-20mW / cm -2 .

[0028] Preferably, the method for photoelectrocatalytic degradation of patulin in a fruit matrix comprises: inserting three electrodes into a quartz dish containing patulin in fruit juice, stirring in the dark, and then performing degradation under light and pressure after adsorption equilibrium is reached.

[0029] Further preferably, the stirring is carried out in the dark for 0-30 min, and the voltage of the pressurized state is 0-1.23 V, excluding 0 V. Different voltages will promote the separation of electron-hole carriers generated by TiO2 nanorods, resulting in different degradation efficiencies.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention utilizes the mesopore size, self-charge and adsorption energy of the vertical pore silica film covering the surface of the TiO2 nanorods to exclude nutrients in the fruit juice from the silica film, allowing the patulin, which is smaller in size and easily adsorbed by the silica pores, to more easily enter the pores and react with active oxygen free radicals for degradation. At the same time, by regulating the thickness of the silica film, the active oxygen free radicals generated by the TiO2 nanorods cannot escape from the silica film pores into the fruit juice, thereby preventing the nutrients in the fruit matrix from being degraded. Therefore, the photoelectrocatalytic method provided by the present invention can achieve stable, precise and efficient degradation of patulin without affecting the nutrients rich in the fruit matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the construction of a photoelectrocatalytic degradation method for patulin in complex apple juice;

[0033] Figure 2 3. The silicon dioxide film morphology of the TiO2 nanorod electrodes prepared in Example 1 of the present invention and Comparative Example 1.

[0034] Figure 3 This is a graph showing the degradation performance of patulin by different modified electrodes provided in Example 1, Example 2, and Comparative Example 1 of the present invention;

[0035] Figure 4 This is a graph showing the effect of treating apple juice with different modified electrodes prepared in Example 1, Comparative Example 2, and Comparative Example 1 on the nutritional quality of apple juice;

[0036] Figure 5 Surface morphology characteristics of different modified electrodes provided in Example 1 of the present invention and Comparative Example 1 after long-term degradation of patulin. DETAILED DESCRIPTION

[0037] The present invention will be further described below with reference to specific embodiments.

[0038] The present invention adopts a one-step hydrothermal method to prepare TiO2 nanorods with high-efficiency photoelectric properties, and further synthesizes an ultrathin silica film on the surface of the TiO2 nanorods. Ultimately, without affecting the nutrients rich in food, it achieves the stable, efficient and precise degradation of penicillin in the fruit matrix.

[0039] Comparative Example 1

[0040] (1) First, a fluorine-doped tin oxide conductive glass electrode was treated with a plasma method for 2 minutes. TiO2 was grown on the surface of the plasma-treated fluorine-doped tin oxide conductive glass electrode. The specific operation was as follows: first, 0.2 mL of tetrabutyl titanate was added dropwise to 10 mL of a mixed solution of deionized water and 36-38 wt% HCl in a ratio of 1:1 (w / w), and the solution was stirred continuously until it became transparent. The mixed solution was placed in a 50 mL polytetrafluoroethylene-lined stainless steel autoclave. Then, the fluorine-doped tin oxide (FTO) electrode, which had been plasma-treated for 2 minutes, was placed in the autoclave at a 45-degree angle to the polytetrafluoroethylene container wall. The reaction system was heated at 150°C for 12 hours and then calcined at 450°C for 1 hour to finally obtain a TiO2 nanorod photoelectrode.

[0041] (2) Using a CHI660E electrochemical workstation, the TiO2 nanorod electrode was used as the working electrode, the platinum electrode was used as the counter electrode, and the Ag / AgCl electrode was used as the reference electrode. A 300W xenon lamp with a 365nm filter was used for irradiation at an intensity of 20mWcm -2 . The prepared photoelectrode (0.5cm -2 ) was inserted into a container containing 5 mL of contaminant (2 mg mL -1 ) in a quartz dish. Stirring was carried out in the dark for 30 minutes to reach adsorption equilibrium. After the photoelectrocatalytic process was initiated, 200 μL of the pollutant solution was collected with a pipette at given time intervals and the changes in pollutant concentration were analyzed.

[0042] When the original TiO2 nanorod electrode was used to degrade patulin, only 55% of it could be degraded within the same degradation time. Figure 2 In addition, scanning electron microscopy and high-resolution transmission electron microscopy images show that after a long period of photoelectrocatalytic treatment, the surface of the exposed TiO2 nanorods dissolves after 10 hours of reaction, as shown in Figure 2. Figure 3 As shown. When degraded in apple juice, the dissolved titanium dioxide nanoparticles may be separated from the apple juice, which will have a negative impact on the quality of apple juice. The effect of TiO2 nanorods on the nutritional quality of apple juice during long-term degradation was further investigated. Figure 4 As shown in the figure, the apple juice after degradation by TiO2 nanorods showed significant changes in its physicochemical and nutritional properties.

[0043] Example 1

[0044] (1) First, a fluorine-doped tin oxide conductive glass electrode was treated with a plasma method for 2 minutes. TiO2 was grown on the surface of the plasma-treated fluorine-doped tin oxide conductive glass electrode. The specific operation was as follows: first, 0.2 mL of tetrabutyl titanate was added dropwise to 10 mL of a mixed solution of deionized water and 36-38 wt% HCl in a ratio of 1:1 (w / w), and the solution was stirred continuously until it became transparent. The mixed solution was placed in a 50 mL polytetrafluoroethylene-lined stainless steel autoclave. Then, the fluorine-doped tin oxide (FTO) electrode, which had been plasma-treated for 2 minutes, was placed in the autoclave at a certain angle to the polytetrafluoroethylene container wall. The reaction system was heated at 150°C for 12 hours and then calcined at 450°C for 1 hour to finally obtain a TiO2 nanorod photoelectrode.

[0045] (2) In order to prepare an ultrathin silica film on the surface of the TiO2 nanorod photoelectrode, 0.16g of hexadecyltrimethylammonium bromide (CTAB), 70mL of deionized water, 30mL of ethanol, 100μL of ammonia water (concentration of 2.5-2.8%) and 80μL of tetraethoxysilane (TEOS) were first mixed in a beaker and stirred for 1h to ensure that the solution was uniform. Subsequently, the TiO2 nanorod photoelectrode was immersed in the solution and reacted at 60°C for 6h, and then placed at 100°C to dry for 12h. Finally, the obtained photoelectrode was immersed in a 0.1mol / L hydrochloric acid ethanol solution, stirred for 10min, and the CTAB was removed, finally obtaining a TiO2 nanorod electrode modified with a silica film with a thickness of 30nm, as shown in FIG. Figure 1 As shown in (b).

[0046] (3) Using a CHI660E electrochemical workstation, an ultrathin silica film-modified TiO2 nanorod electrode was used as the working electrode, a platinum electrode was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode. A 300W xenon lamp with a 365nm filter was used for irradiation at an intensity of 20mW cm -2 . Place the prepared photoelectrode (0.5cm -2 ) was inserted into a container containing 5 mL of contaminant (2 mg mL -1 ) in a quartz dish. Stir for 30 minutes in the dark to reach adsorption equilibrium. After the photoelectrocatalytic process is started, 200 μL of pollutant solution is collected at given time intervals using a pipette and the changes in pollutant concentration are analyzed, such as Figure 1 As shown in (a), the reactive oxygen radicals generated by patulin and TiO2 nanorods are confined within the pores of the silica membrane, achieving precise degradation of patulin in apple juice without affecting the nutritional value of the apple juice.

[0047] The difference from Comparative Example 1 is that the surface of the TiO2 nanorods is modified with a 30 nm thick silicon dioxide film, such as Figure 5 As shown, the constructed silicon membrane has uniform ultra-thin vertical channels with a thickness of 30nm and a pore size of 2.3nm.

[0048] Firstly, the photoelectrocatalytic performance of the electrodes was investigated, e.g. Figure 2 As shown, the silica film-modified TiO2 nanorod electrode (SM-TiO2 NRs) prepared in this example was found to have a 90% degradation efficiency for patulin, while the pristine TiO2 nanorods (TiO2 NRs) prepared in Comparative Example 1 only degraded 55% within the same degradation time. The enhanced degradation efficiency of the silica film-modified TiO2 nanorods prepared in this example is primarily due to the enhanced interfacial water reaction within the nanoconfined space, which promotes the generation of reactive oxygen free radicals. Furthermore, the catalytic reaction within the nanoconfined space enhances the collision between reactive oxygen free radicals and patulin, thereby improving the catalytic degradation efficiency of patulin.

[0049] In addition, the silica film modified TiO2 nanorods prepared in Example 1 have excellent stability. Figure 3 As shown, scanning electron microscopy images reveal that the morphology of the silica-film-modified TiO2 nanorods prepared in this example remains unchanged after prolonged photoelectrocatalytic treatment, while the surface of the bare TiO2 nanorods prepared in Comparative Example 1 dissolves after 10 hours of reaction. During degradation in apple juice, the dissolved titanium dioxide nanoparticles may escape into the juice, negatively impacting its quality. Notably, the in situ growth of the ultrathin silica film on the TiO2 nanorod surface significantly enhances its structural and chemical stability, preventing food contamination caused by photoelectrode instability.

[0050] The effects of long-term treatment of apple juice with different modified electrodes on the nutritional quality of apple juice, including total sugar, total phenols, total flavonoids, DPPH scavenging rate, soluble solids and titratable acid, were further investigated. Figure 4 As shown in Figure 1, the apple juice after degradation of the bare TiO2 nanorods prepared in Comparative Example 1 exhibited significant changes in both its physicochemical and nutritional properties. However, the apple juice after degradation of the silica-film-modified TiO2 nanorods prepared in this example retained its original nutritional composition. This phenomenon is primarily attributed to the catalytic effect of reactive oxygen species within the confined space and the excellent nutrient barrier capability of the ultrathin silica film, which effectively prevented the interaction between reactive oxygen species and food nutrients, thereby achieving efficient PEC treatment while maximizing the protection of food nutrients.

[0051] Comparative Example 2

[0052] Compared with Example 1, the difference is that The thickness of the silicon dioxide film modified on the surface of TiO2 nanorods by solution growth method is 10nm.

[0053] The apple juice after degradation of the electrode with 30nm silicon dioxide film modified on the surface of TiO2 nanorods prepared in Example 1 has no significant changes in its physical, chemical and nutritional properties. However, the apple juice after degradation of the electrode with 10nm silicon dioxide film modified on the surface of TiO2 nanorods prepared in this comparative example has significant changes in its physical, chemical and nutritional properties, such as Figure 4 This is primarily because the diffusion distance of reactive oxygen radicals generated by the TiO2 nanorods is approximately 15 nm. When the silica film is less than 15 nm thick, these radicals diffuse into the apple juice, indiscriminately destroying the physical, chemical, and nutritional components in the juice. When the thickness is greater than 15 nm, the reactive oxygen radicals generated by the TiO2 nanorods are confined within the pores of the inert silica film, thereby protecting the physical, chemical, and nutritional components in the apple juice.

[0054] Example 2

[0055] Compared with Example 1, the difference is that The thickness of the silicon dioxide film modified on the surface of TiO2 nanorods by solution growth method is 40nm.

[0056] In Example 2, when the thickness of the silica film modified TiO2 nanorods is 40 nm, the degradation efficiency of patulin is higher than that of the bare TiO2 nanorods prepared in Comparative Example 1 within the same degradation time. Figure 3 This is mainly because the excessively thick inert dioxide film grown on the surface of TiO2 nanorods hinders the mass transfer of water molecules, resulting in a decrease in the number of active sites on the surface of TiO2 nanorods, thereby reducing the degradation efficiency of penicillin.

Claims

1. A photoelectrocatalytic degradation method for patulin in a fruit matrix, characterized in that: include: Step 1: growing TiO2 on the surface of a plasma-treated fluorine-doped tin oxide conductive glass electrode, and annealing to obtain a TiO2 nanorod electrode; Step 2: Pass Solution growth method, growing a silicon dioxide film with a thickness of 15–40 nm on the surface of the TiO2 nanorod electrode, and then cleaning the excess after annealing. The solution obtained a TiO2 nanorod electrode modified with a vertical pore silica film; Step 3: insert the TiO2 nanorod electrode into the fruit juice and use it as a working electrode, a platinum electrode as a counter electrode, and an Ag / AgCl electrode as a reference electrode. Under light illumination, the patulin in the apple juice is degraded by photoelectrocatalysis.

2. The photoelectrocatalytic degradation method of patulin in a fruit matrix according to claim 1, characterized in that: The plasma treatment time was 0–2 min, excluding 0 min.

3. The photoelectrocatalytic degradation method of patulin in a fruit matrix according to claim 1, characterized in that: The preparation method of the TiO2 nanorod electrode comprises: Tetrabutyl titanate was added dropwise to a mixed solution of deionized water and 36-38 wt% hydrochloric acid; The solution was stirred continuously until it became transparent and then transferred to a Teflon-lined stainless steel autoclave; The fluorine-doped tin oxide conductive glass obtained in step 1 was placed in an autoclave, and the polytetrafluoroethylene container wall was kept at an angle of 30–45° for growth.

4. The photoelectrocatalytic degradation method of patulin in a fruit matrix according to claim 1, characterized in that: In step 1, the annealing temperature is 400-600° C., and the annealing time is 1-5 hours.

5. The photoelectrocatalytic degradation method of patulin in a fruit matrix according to claim 1, characterized in that: The The solution growth method comprises: mixing hexadecyltrimethylammonium bromide, deionized water, ethanol, ammonia water and tetraethoxysilane in a beaker and stirring; then, immersing a TiO2 nanorod electrode in the solution to grow silicon dioxide.

6. The photoelectrocatalytic degradation method of patulin in a fruit matrix according to claim 1, characterized in that: In step 2, the annealing temperature is 80-120°C, and the annealing time is 12-36 hours.

7. The photoelectrocatalytic degradation method of patulin in a fruit matrix according to claim 1, characterized in that: Wash off excess with hydrochloric acid ethanol solution The concentration of the hydrochloric acid ethanol solution is 0.05-0.1 mol / L, and the elution time is 10-15 min.

8. The photoelectrocatalytic degradation method of patulin in a fruit matrix according to claim 1, characterized in that: A 300W xenon lamp equipped with a 365nm filter was used for light illumination, with an intensity of 5–20mW / cm -2 .

9. The photoelectrocatalytic degradation method of patulin in a fruit matrix according to claim 1, characterized in that: The method for photoelectrocatalytic degradation of patulin in a fruit matrix comprises: inserting three electrodes into a quartz dish containing patulin in fruit juice, stirring in the dark, and then degrading under light and pressure after reaching adsorption equilibrium.

10. The photoelectrocatalytic degradation method of patulin in a fruit matrix according to claim 9, characterized in that: The mixture was stirred in the dark for 0–30 min, and the voltage of the pressurization was 0–1.23 V, excluding 0 V.

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