Preparation method of iodine and nitrogen co-doped TiO photocatalyst for degrading mycotoxin DON

Abstract

The invention discloses a preparation method of an iodine and nitrogen co-doped TiO photocatalyst for degrading mycotoxin DON, and relates to a preparation method of a TiO photocatalyst. In order to solve the problems of higher cost, lower degradation speed and longer fermentation period of a biological method, the method comprises the following steps: dissolving tetrabutyl titanate and acetic acid in absolute ethyl alcohol to prepare a solution A, dissolving urea in water to form a solution B, dissolving potassium iodate in water to form a solution C, mixing the solution B, the solution C and the solution A, and stirring to obtain a mixed solution; meanwhile, stirring until the solution becomes sol and gel, standing the gel, drying, grinding and calcining to obtain the photocatalyst. According to the preparation method, TiO2 is co-doped with an element I and N, and the photocatalytic activity of I doping is improved by changing a lattice structure, introducing oxygen vacancies and the like; n doping can form a new energy level by replacing oxygen atoms in TiO2 crystal lattices or occupying the interstitial positions of the crystal lattices, so that the band gap is reduced. The invention belongs to the field of photocatalyst preparation.

Description

Technical Field

[0001] This invention relates to a method for preparing a TiO2 photocatalyst. Background Technology

[0002] Mycotoxins are toxic secondary metabolites produced by molds during their growth in food and feed. Due to their carcinogenic, teratogenic, and mutagenic properties, they pose a significant threat to human and animal health and have become a global food safety concern. Deoxynivalenol (DON), a common mycotoxin, is primarily produced by fungi of the genus *Fusarium* and is a type B trichothecene toxin. DON contamination is extremely prevalent during the harvesting, storage, and processing of grains and their products, severely harming agricultural development and posing a significant threat to livestock and human health. Research data shows that DON has become one of the most widely distributed mycotoxins globally, with an average contamination rate of up to 59% in grains, exhibiting significant regional differences. The contamination rate is 50% in Asia, as high as 76% in Africa, and particularly severe in some European countries. The presence of DON not only threatens food security and can lead to substantial economic losses but also poses potential health hazards to humans through the food chain.

[0003] The chemical formula of DON is C 15 H 20 O6, with a molecular weight of 296.32 g / mol, is a white crystalline solid at room temperature. It exhibits thermal stability and resistance to acids and alkalis, remaining stable at 120°C and only beginning to decompose at 210°C. The main toxic group of DON is carbon. 12 -C 13 Epoxy groups at positions C3, C7, C6 15 hydroxyl group at position C9-C 10 The double bonds in DON make it difficult to remove using conventional processing methods, posing a significant threat to food and feed safety. Therefore, developing efficient, safe, and pollution-free detoxification technologies is crucial.

[0004] DON toxicity primarily manifests through mechanisms such as inhibiting protein synthesis, inducing oxidative stress, and triggering apoptosis. The epoxy groups in the DON molecule can bind to peptidyl transferases on ribosomes, preventing peptide chain synthesis and thus inhibiting protein synthesis. Furthermore, DON can activate multiple signaling pathways, such as P38, JNK, and ERK1 / 2, inducing ribosomal toxicity, generating cellular inflammation, and triggering apoptosis. DON has a wide range of toxic effects, including damage to the gut, liver, immune system, and nervous system. It also exhibits genotoxicity, increasing the risk of teratogenicity, carcinogenicity, and mutagenicity. Given the widespread contamination and toxic effects of DON, various countries have established strict limits. For example, China stipulates that the limit for DON in grains such as corn and wheat is ≤1 mg / kg, and for plant-based feed ingredients it is ≤5 mg / kg.

[0005] Currently, DON reduction technologies mainly include physical, chemical, and biological methods. Physical methods, such as adsorbents, heat treatment, irradiation, and cold plasma, can reduce DON content through physical adsorption or high-temperature treatment. Chemical methods primarily rely on strong acids, strong bases, and redox reactions to degrade DON, but may produce toxic chemical residues, affecting the nutritional quality of food. Biological methods utilize the selective degradation by microorganisms or enzymes, exhibiting environmental friendliness and high degradation efficiency, but suffer from high costs, slow degradation rates, and long fermentation periods. Therefore, researching a novel, efficient, safe, and pollution-free detoxification technology is of significant theoretical and practical importance. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problems of high cost, slow degradation rate and long fermentation period of biological methods, and to provide a method for preparing iodine and nitrogen co-doped TiO2 photocatalyst for degrading mycotoxin DON.

[0007] The preparation method of iodine and nitrogen co-doped TiO2 photocatalyst for degrading mycotoxin DON is as follows:

[0008] Solution A was prepared by dissolving 10 mL of tetrabutyl titanate and 3 mL of acetic acid in 20 mL of anhydrous ethanol. Solution B was prepared by dissolving urea in 4 mL of water. Solution C was prepared by dissolving potassium iodate in 4 mL of water. Solution B, solution C and solution A were mixed and stirred until the solution became a sol and then a gel. The gel was allowed to stand for 24 h, dried at 80 °C and ground. The gel was then calcined at 400 °C for 2 h to obtain the photocatalyst (I(5%)-N(30%)-TiO2 photocatalyst).

[0009] Photocatalysis, as an emerging oxidation technology, utilizes photocatalysts to generate highly oxidizing reactive oxygen species under light irradiation, thereby degrading organic pollutants. TiO2, as a commonly used photocatalyst, has advantages such as low cost, non-toxicity, and reusability, and is widely used in wastewater treatment, hydrogen production, and other fields. TiO2 mainly exists in three crystal forms: anatase, rutile, and brookite, among which the anatase phase exhibits higher photocatalytic activity. TiO2 has a band gap of 3.2 eV. Under ultraviolet light irradiation, valence band electrons absorb photon energy and transition to the conduction band, forming electron-hole pairs, which in turn generate reactive oxygen species such as hydroxyl radicals (·OH), thus achieving the degradation of organic pollutants.

[0010] This invention utilizes the co-doping of TiO2 with iron (I) and nitrogen (N). I doping enhances photocatalytic activity by altering the crystal structure and introducing oxygen vacancies, while N doping reduces the band gap by replacing oxygen atoms in the TiO2 lattice or occupying interstitial positions, thus creating new energy levels. The synergistic effect of I and N co-doping further improves the photocatalytic performance of TiO2, enabling the preparation of a highly efficient photocatalyst. The photocatalytic reaction conditions were optimized, and its degradation effect on dinoxylene (DON) was evaluated. The research results will provide an efficient and safe method for the detoxification of DON from grains and their products, and also provide a theoretical basis for the application of photocatalysis technology in food and feed safety. Attached Figure Description

[0011] Figure 1 This is a comparison of the degradation efficiency of DON by the composite photocatalyst I(3%)-N(20%)-TiO2, I(3%)-N(30%)-TiO2, and I(3%)-N(50%)-TiO2 photocatalysts in Experiment 1. Figure (a) shows the comparison of the degradation efficiency of DON by I(3%)-N(20%)-TiO2, I(3%)-N(30%)-TiO2, and I(3%)-N(50%)-TiO2 photocatalysts; (b) shows the comparison of the degradation efficiency of DON by I(5%)-N(20%)-TiO2, I(5%)-N(30%)-TiO2, and I(5%)-N(50%)-TiO2 photocatalysts; and (c) shows the comparison of the degradation efficiency of DON by I(7%)-N(20%)-TiO2, I(7%)-N(30%)-TiO2, and I(7%)-N(50%)-TiO2 photocatalysts. - Comparison of the degradation efficiency of DON by TiO2 photocatalyst, (d) represents the comparison of the degradation efficiency of DON by TiO2, N(30%)-TiO2 photocatalyst, I(5%)-TiO2 photocatalyst, and I(5%)-N(30%)-TiO2 photocatalyst.

[0012] Figure 2 This is a comparison chart of the effects of the amount of I(5%)-N(30%)-TiO2 photocatalyst and the degradation time on the degradation rate of DON in Experiment 1;

[0013] Figure 3 This is a comparison chart of the reuse efficiency of I(5%)-N(30%)-TiO2 photocatalyst in Experiment 1;

[0014] Figure 4 These are SEM images of TiO2, N(30%)-TiO2 photocatalyst, I(5%)-TiO2 photocatalyst, and I(5%)-N(30%)-TiO2 photocatalyst in Experiment 1. In the figure, (a) represents the SEM image of TiO2, (b) represents the SEM image of N(30%)-TiO2 photocatalyst, (c) represents the SEM image of I(5%)-TiO2 photocatalyst, and (d) represents the SEM image of I(5%)-N(30%)-TiO2 photocatalyst.

[0015] Figure 5 These are SEM images of TiO2, N(30%)-TiO2 photocatalyst, I(5%)-TiO2 photocatalyst, and I(5%)-N(30%)-TiO2 photocatalyst in Experiment 1. In the figure, (a) represents the TEM image of TiO2, (b) represents the TEM image of N(30%)-TiO2 photocatalyst, (c) represents the TEM image of I(5%)-TiO2 photocatalyst, and (d) represents the TEM image of I(5%)-N(30%)-TiO2 photocatalyst.

[0016] Figure 6 These are the XRD patterns of TiO2, N(30%)-TiO2 photocatalyst, I(5%)-TiO2 photocatalyst, and I(5%)-N(30%)-TiO2 photocatalyst in Experiment 1. In the figure, (a) represents the XRD pattern of TiO2, (b) represents the XRD pattern of N(30%)-TiO2 (N-TiO2) photocatalyst, (c) represents the XRD pattern of I(5%)-TiO2 (I-TiO2) photocatalyst, and (d) represents the XRD pattern of I(5%)-N(30%)-TiO2 (NI-TiO2) photocatalyst.

[0017] Figure 7 These are the Fourier transform infrared (FTIR) spectra of TiO2, N(30%)-TiO2 photocatalyst, I(5%)-TiO2 photocatalyst, and I(5%)-N(30%)-TiO2 photocatalyst in Experiment 1. In the figure, (a) represents the Fourier transform infrared spectrum of TiO2, (b) represents the Fourier transform infrared spectrum of N(30%)-TiO2 (N-TiO2) photocatalyst, (c) represents the Fourier transform infrared spectrum of I(5%)-TiO2 (I-TiO2) photocatalyst, and (d) represents the Fourier transform infrared spectrum of I(5%)-N(30%)-TiO2 (IN-TiO2) photocatalyst.

[0018] Figure 8 The figures show the UV-Vis diffuse reflectance spectra and bandgap diagrams of TiO2, N(30%)-TiO2 photocatalyst, I(5%)-TiO2 photocatalyst, and I(5%)-N(30%)-TiO2 photocatalyst in Experiment 1. In the figures, (a) represents the UV-Vis diffuse reflectance spectra of the photocatalysts, and (b) represents the bandgap diagram of I(5%)-N(30%)-TiO2.

[0019] Figure 9 The degradation rate and TOC removal rate during the DON photocatalytic degradation process in Experiment 1;

[0020] Figure 10 The images show the chromatograms of the photocatalytic degradation of DON by I(5%)-N(30%)-TiO2 and its degradation products in Experiment 1. (a) shows the high-performance liquid chromatogram of the photocatalytic degradation of 15 μg / mL DON; (b) shows the total ion current chromatogram of 15 μg / mL DON; and (c) shows the total ion current chromatogram of the DON degradation products.

[0021] Figure 11 These are the first-order mass spectra and structural formulas of the DON products P1, P2, and P3 obtained by photocatalytic degradation of I(5%)-N(30%)-TiO2 in Experiment 1. In the figure, (a) represents P1, (b) represents P2, and (c) represents P3.

[0022] Figure 12 This is a comparison of cell morphology changes in IPEC-J2 cells after incubation with different concentrations of I(5%)-N(30%)-TiO2 for 24 hours in Experiment 1.

[0023] Figure 13 This is a comparison of cell morphology changes in IPEC-J2 cells after 24 h of incubation with DON photocatalytic degradation products in Experiment 1.

[0024] Figure 14 This is a comparison of the relative cell proliferation rates of IPEC-J2 cells incubated with different concentrations of I(5%)-N(30%)-TiO2 for 24 h in Experiment 1 (Note: the same letter or no letter between groups indicates no significant difference (P>0.05), different letters indicate significant difference (P<0.05)).

[0025] Figure 15 This is a comparison of the relative cell proliferation rates of IPEC-J2 cells after 24 h of incubation with different DON photocatalytic degradation products in Experiment 1 (Note: the same letter or no letter between groups indicates no significant difference (P>0.05), different letters indicate significant difference (P<0.05)).

[0026] Figure 16This is a comparison of the effects of different concentrations of I(5%)-N(30%)-TiO2 on apoptosis in IPEC-J2 cells in Experiment 1.

[0027] Figure 17 This is a comparative diagram showing the effects of DON and its degradation products on apoptosis in IPEC-J2 cells in Experiment 1.

[0028] Figure 18 The effect of I(5%)-N(30%)-TiO2 photocatalytic treatment time on DON degradation efficiency in Experiment 1.

[0029] Figure 19 This is a comparison chart of the effects of I(5%)-N(30%)-TiO2 on the protein content in corn steep liquor in Experiment 1;

[0030] Figure 20 This is a comparison chart of the effects of I(5%)-N(30%)-TiO2 on the reducing sugar content in corn steep liquor in Experiment 1;

[0031] Figure 21 This is a comparison graph showing the effect of I(5%)-N(30%)-TiO2 on the pH value of corn steep liquor solution in Experiment 1;

[0032] Figure 22 This is a comparison chart of the effects of I(5%)-N(30%)-TiO2 on the lactic acid content in corn steep liquor in Experiment 1;

[0033] Figure 23 This is a comparison chart of the effects of I(5%)-N(30%)-TiO2 on the odor of corn steep liquor in Experiment 1. Detailed Implementation

[0034] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0035] Specific Implementation Method 1: The preparation method of the iodine and nitrogen co-doped TiO2 photocatalyst for degrading mycotoxin DON in this implementation method is as follows:

[0036] Solution A was prepared by dissolving 10 mL of tetrabutyl titanate and 3 mL of acetic acid in 20 mL of anhydrous ethanol. Solution B was prepared by dissolving urea in 4 mL of water. Solution C was prepared by dissolving potassium iodate in 4 mL of water. Solution B, solution C and solution A were mixed and stirred until the solution became a sol and then a gel. The gel was allowed to stand for 24 h, dried at 80 °C and ground. The gel was then calcined at 400 °C for 2 h to obtain the photocatalyst (I(5%)-N(30%)-TiO2 photocatalyst).

[0037] The following experiments were used to verify the effectiveness of the invention:

[0038] Experiment 1:

[0039] 2. Materials and Methods

[0040] 2.1 Synthesis of TiO2 photocatalysts with different N and I doping levels

[0041] The photocatalyst was prepared by the sol-gel method. 10 mL of tetrabutyl titanate and 3 mL of acetic acid were dissolved in 20 mL of anhydrous ethanol to prepare solution A. Urea was dissolved in water to form an aqueous solution B with a concentration of 4.35 mol / L N. Potassium iodate was dissolved in water to form an aqueous solution C with a concentration of 0.36 mol / L I. Solution B or solution C was slowly added dropwise to solution A while stirring until the solution became a sol and a gel. The gel was allowed to stand for 24 h, dried at 80 °C, ground, and calcined at 400 °C for 2 h to obtain N(30%)-TiO2 photocatalyst or I(5%)-TiO2 photocatalyst.

[0042] The preparation method of I(3%)-N(20%)-TiO2 photocatalyst is as follows:

[0043] Solution A was prepared by dissolving 10 mL of tetrabutyl titanate and 3 mL of acetic acid in 20 mL of anhydrous ethanol. Solution B was prepared by dissolving urea in 4 mL of water. Solution C was prepared by dissolving potassium iodate in 4 mL of water. Solution B, solution C and solution A were mixed and stirred until the solution became a sol and then a gel. The gel was allowed to stand for 24 h, dried at 80 °C and ground. The gel was then calcined at 400 °C for 2 h to obtain I(3%)-N(20%)-TiO2 photocatalyst.

[0044] The preparation method of I(3%)-N(30%)-TiO2 photocatalyst is as follows:

[0045] Solution A was prepared by dissolving 10 mL of tetrabutyl titanate and 3 mL of acetic acid in 20 mL of anhydrous ethanol. Solution B was prepared by dissolving urea in 4 mL of water. Solution C was prepared by dissolving potassium iodate in 4 mL of water. Solution B, solution C and solution A were mixed and stirred until the solution became a sol and then a gel. The gel was allowed to stand for 24 h, dried at 80 °C and ground. The gel was then calcined at 400 °C for 2 h to obtain I(3%)-N(30%)-TiO2 photocatalyst.

[0046] The preparation method of I(3%)-N(50%)-TiO2 photocatalyst is as follows:

[0047] Solution A was prepared by dissolving 10 mL of tetrabutyl titanate and 3 mL of acetic acid in 20 mL of anhydrous ethanol. Solution B was prepared by dissolving urea in 4 mL of water. Solution C was prepared by dissolving potassium iodate in 4 mL of water. Solution B, solution C and solution A were mixed and stirred until the solution became a sol and then a gel. The gel was allowed to stand for 24 h, dried at 80 °C and ground. The gel was then calcined at 400 °C for 2 h to obtain I(3%)-N(50%)-TiO2 photocatalyst.

[0048] The preparation method of I(5%)-N(20%)-TiO2 photocatalyst is as follows:

[0049] Solution A was prepared by dissolving 10 mL of tetrabutyl titanate and 3 mL of acetic acid in 20 mL of anhydrous ethanol. Solution B was prepared by dissolving urea in 4 mL of water. Solution C was prepared by dissolving potassium iodate in 4 mL of water. Solution B, solution C and solution A were mixed and stirred until the solution became a sol and then a gel. The gel was allowed to stand for 24 h, dried at 80 °C and ground. The gel was then calcined at 400 °C for 2 h to obtain I(5%)-N(20%)-TiO2 photocatalyst.

[0050] The preparation method of I(5%)-N(50%)-TiO2 photocatalyst is as follows:

[0051] Solution A was prepared by dissolving 10 mL of tetrabutyl titanate and 3 mL of acetic acid in 20 mL of anhydrous ethanol. Solution B was prepared by dissolving urea in 4 mL of water. Solution C was prepared by dissolving potassium iodate in 4 mL of water. Solution B, solution C and solution A were mixed and stirred until the solution became a sol and then a gel. The gel was allowed to stand for 24 h, dried at 80 °C and ground. The gel was then calcined at 400 °C for 2 h to obtain I(5%)-N(50%)-TiO2 photocatalyst.

[0052] The preparation method of I(7%)-N(20%)-TiO2 photocatalyst is as follows:

[0053] Solution A was prepared by dissolving 10 mL of tetrabutyl titanate and 3 mL of acetic acid in 20 mL of anhydrous ethanol. Solution B was prepared by dissolving urea in 4 mL of water. Solution C was prepared by dissolving potassium iodate in 4 mL of water. Solution B, solution C and solution A were mixed and stirred until the solution became a sol and then a gel. The gel was allowed to stand for 24 h, dried at 80 °C and ground. The gel was then calcined at 400 °C for 2 h to obtain I(7%)-N(20%)-TiO2 photocatalyst.

[0054] The preparation method of I(7%)-N(30%)-TiO2 photocatalyst is as follows:

[0055] Solution A was prepared by dissolving 10 mL of tetrabutyl titanate and 3 mL of acetic acid in 20 mL of anhydrous ethanol. Solution B was prepared by dissolving urea in 4 mL of water. Solution C was prepared by dissolving potassium iodate in 4 mL of water. Solution B, solution C and solution A were mixed and stirred until the solution became a sol and then a gel. The gel was allowed to stand for 24 h, dried at 80 °C and ground. The gel was then calcined at 400 °C for 2 h to obtain I(7%)-N(30%)-TiO2 photocatalyst.

[0056] The preparation method of I(7%)-N(50%)-TiO2 photocatalyst is as follows:

[0057] Solution A was prepared by dissolving 10 mL of tetrabutyl titanate and 3 mL of acetic acid in 20 mL of anhydrous ethanol. Solution B was prepared by dissolving urea in 4 mL of water. Solution C was prepared by dissolving potassium iodate in 4 mL of water. Solution B, solution C and solution A were mixed and stirred until the solution became a sol and then a gel. The gel was allowed to stand for 24 h, dried at 80 °C and ground. The gel was then calcined at 400 °C for 2 h to obtain I(7%)-N(50%)-TiO2 photocatalyst.

[0058] 2.2 Photocatalytic degradation efficiency of DON by TiO2 and composite photocatalysts

[0059] The photocatalysts N(30%)-TiO2, I(5%)-TiO2, and I(5%)-N(30%)-TiO2 prepared in section 2.1 were added to a DON solution with a concentration of 5 µg / mL to achieve a concentration of 5 mg / mL. The solution was stirred in the dark for 1 h to reach adsorption-desorption equilibrium. Photocatalytic treatment was then performed under a xenon lamp (400 nm–780 nm) at a distance of 20 cm for different irradiation times (1 h, 2 h, 4 h, 6 h). 400 µL of the reaction solution was collected, centrifuged at 8000 rpm for 10 min, and the supernatant was filtered through a 0.22 µm filter membrane for DON analysis. High-performance liquid chromatography (HPLC) was used with a C18 column, a mobile phase of methanol-water (20:80 v / v), a flow rate of 0.8 mL / min, a temperature of 35 °C, and a detection wavelength of 218 nm. The DON degradation rate was calculated using the following formula:

[0060] η(%)=(C0−C t ) / C0×100

[0061] Where C0 is the initial concentration of DON, C t The concentration of DON after photocatalytic degradation.

[0062] 2.3 Characterization and Analysis of Composite Photocatalysts

[0063] 2.3.1 Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) Analysis

[0064] The surface morphology of TiO2 and the synthesized N(30%)-TiO2 photocatalyst, I(5%)-TiO2 photocatalyst and I(5%)-N(30%)-TiO2 photocatalyst were analyzed using scanning electron microscopy (SU8010, Hitachi, Japan) and transmission electron microscopy (H-7650, Hitachi, Japan).

[0065] 2.3.2 Characterization and analysis of specific surface area (BET)

[0066] After drying, the samples were passed through a 200-mesh sieve. The specific surface areas of TiO2, N(30%)-TiO2 photocatalyst, I(5%)-TiO2 photocatalyst, and I(5%)-N(30%)-TiO2 photocatalyst were tested using an auto IQ instrument (Kunta Instruments, Inc., USA). The specific surface areas of the above photocatalysts were calculated.

[0067] 2.3.3 X-ray diffraction (XRD) characterization analysis

[0068] X-ray diffractometer (D8 X Advance, Bruker, Germany) was used with Cukα as the X-ray source, a scanning range of 10–90°, a scanning speed of 0.05 ° / s (λ = 0.15406 nm, voltage 40 kV, current 40 mA, graphite monochromator) to analyze the crystal structure of the samples. Raw data were processed using Jade, and the grain size of the samples was estimated from the full width at half maximum (FWHM) of the diffraction peaks using the Scherrer formula.

[0069]

[0070] In the formula: D is the particle size; K is 0.89; λ is the incident light wavelength of the X-ray diffractometer; θ is the diffraction angle; 1 / 2β is the full width at half maximum (FWHM).

[0071] 2.3.4 Fourier Transform Infrared Spectroscopy (FT-IR) Characterization Analysis

[0072] TiO2, N(30%)-TiO2 photocatalyst, I(5%)-TiO2 photocatalyst, and I(5%)-N(30%)-TiO2 photocatalyst were dried and passed through a 200-mesh sieve, then uniformly mixed with potassium bromide and pressed into tablets. The prepared photocatalyst samples were analyzed using a Fourier transform infrared spectrometer (Is50, Thermo Fisher Scientific, Germany) with a wavelength range of 400-4000 cm⁻¹. -1 The data is processed and analyzed using OMNIC software.

[0073] 2.3.5 Characterization and analysis of ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS)

[0074] After grinding and drying, the test samples were passed through a 200-mesh sieve. The UV-Vis diffuse reflectance spectra were measured using a UV-Vis spectrophotometer (Lambda, PerkinElmer, USA) with a small integrating sphere attachment. BaSO4 powder was used as a blank for correction. The scanning range was 800 nm to 200 nm. The changes in the band gap width of the photocatalyst were analyzed. The band gap width was calculated using the formula:

[0075] (αhν)^(1 / n)=A(hν-Eg)

[0076] Where h is Planck's constant, ν is the frequency, α is the absorbance, and A is the proportionality constant.

[0077] 2.4 Identification of DON degradation products

[0078] The DON solution was degraded using I(5%)-N(30%)-TiO2 photocatalyst according to method 2.2. Samples were taken at 4 h, 8 h, 12 h, 16 h, and 20 h of reaction. The DON degradation rate was determined by high performance liquid chromatography (HPLC). The elution conditions are shown in Table 2-1. The molecular formula and molecular structure of the DON photocatalytic products were analyzed and identified using ultra-high performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry (UPLC / Q-TOF / MS). The detection conditions are shown in Tables 2-2 and 2-3.

[0079] Table 2-1 Ultra-high performance liquid chromatography elution conditions for DON degradation products

[0080] Time (min) Acetonitrile (%) 0.1% formic acid solution (%) 0 2 98 1 50 50 5 50 50 10 95 5 12 95 5 15 2 98

[0081] Table 2-2 Ultra-high performance liquid chromatography conditions for the detection of DON degradation products

[0082] project parameter chromatographic column C18 column detector Ultraviolet detector mobile phase Pure acetonitrile and 0.1% formic acid solution Column temperature 30℃ Injection volume 5 μL Flow rate 0.3 mL / min

[0083] Table 2-3 Mass spectrometry detection conditions for DON degradation products

[0084] project parameter Scanning mode Positive ion mode Collection time 12 min Scanning method Full scan Scan range 50 m / z-1000 m / z Capillary voltage 3.5 kV Cone voltage 30 kV

[0085] 2.5 Effects of I(5%)-N(30%)-TiO2 photocatalyst and DON degradation products on cell viability

[0086] IPEC-J2 cells were cultured in DMEM medium at 37°C in a 5% CO2 incubator. When the cells grew to 80-90%, the culture medium was discarded, and the cells were digested with trypsin. The obtained cells were used for further experiments.

[0087] The complete culture medium was adjusted to a cell density of 1×10⁻⁶. 5 Cells were seeded at 1.0 mL / mL in 12-well plates and cultured at 37°C with 5% CO2 until adherence. The culture medium was discarded, and the cells were washed twice with PBS. 100 μL of serum-free medium containing different concentrations of I(5%)-N(30%)-TiO2 photocatalyst or photocatalytic degradation products of DON was added to each well. The cells were cultured for 24 h, and cell morphology was observed under a fluorescence inverted microscope.

[0088] The complete culture medium was adjusted to a cell density of 3 × 10⁻⁶. 5100 μL of cells were seeded per well in 96-well plates and cultured at 37°C in a 5% CO2 incubator. After cell attachment, the culture medium was discarded, and the cells were washed twice with PBS. 100 μL of serum-free medium containing different concentrations of I(5%)-N(30%)-TiO2 photocatalyst or photocatalytic degradation products of DON were added to each well. After 24 h, 50 μL of MTT solution (manufacturer: Nanjing Jiancheng Bioengineering Institute) was added, and the cells were incubated for 4 h. The culture medium was then discarded, and 100 μL of LDMSO (manufacturer: Sigma-Aldrich, USA) was added to each well. The plates were shaken for 15 min, and the OD value at 570 nm was measured using a microplate reader to calculate the cell proliferation rate.

[0089] The complete culture medium was adjusted to a cell reconcentration of 1×10⁻⁶. 5 Cells were seeded at a density of 100 μL / mL into 24-well cell culture plates. The cells were cultured until they adhered to the plates, and the culture medium was discarded. The cells were washed twice with PBS solution, and serum-free DME / F-12 medium (Hyclone, USA) containing different concentrations of photocatalyst or DON degradation products with different degradation times were added. The cells were cultured for another 24 h. The apoptosis detection kit was used to detect cell apoptosis.

[0090] 2.6 Degradation efficiency of I(5%)-N(30%)-TiO2 photocatalyst for DON in corn steep liquor

[0091] I(5%)-N(30%)-TiO2 photocatalyst was added to corn syrup (dry matter content 10%, DON content 5 µg / mL) to achieve a concentration of 5 mg / mL. Photocatalytic treatment was then performed under a xenon lamp (400 nm–780 nm). After irradiation, 1 mL of corn syrup was transferred, centrifuged at 8000 rpm for 5 min, and the supernatant was added to a DON affinity column. The column was allowed to pass through under gravity, washed twice with PBS and deionized water, and the column was purged with a syringe until no liquid flowed out. All DON on the affinity column was eluted with the same volume of chromatographic methanol as the original solution. The collected solution was dried under nitrogen at 50°C, and 2 mL of mobile phase (containing 2% acetonitrile and 0.1% formic acid) was added and reconstituted by shaking. The solution was filtered through a 0.22 µm filter membrane, and the DON content was determined by high-performance liquid chromatography (HPLC).

[0092] 2.7 Effects of I(5%)-N(30%)-TiO2 on the nutritional quality of corn steep liquor

[0093] Centrifuge the 2.6 photocatalyzed corn syrup at 8000 rpm for 8 min, freeze-dry the supernatant, grind it through a 40-mesh sieve, and use it for the determination of the following indicators.

[0094] 2.7.1 Effect on crude protein content

[0095] The Kjeldahl method was used to determine the nitrogen content of the sample. 0.2 g of photocatalyzed freeze-dried corn syrup was weighed, added to the bottom of a digestion tube and mixed with the mixed catalyst. 10 mL of concentrated sulfuric acid was added, and the solution was digested in a high-temperature digestion furnace until it became clear. The solution was then analyzed using an automated protein analyzer.

[0096] 2.7.2 Effect on amino acid content

[0097] Take 50 mg of photocatalyzed lyophilized corn syrup sample into a hydrolysis tube, add 7 mL of 6 mol / L HCl, purge with N2 for about 50 s, quickly tighten the cap of the hydrolysis tube, hydrolyze at 110℃ for 22 h, cool to room temperature, transfer the hydrolysate to a 50 mL volumetric flask and make up to volume, take 2 mL of the lyophilized sample, add 1 mL of 0.02 mol / L HCl solution, centrifuge at 14000 rpm for 15 min, take the supernatant and filter through a 0.45 µm filter membrane into a special vial for amino acid analysis, and perform detection using an automated amino acid analyzer.

[0098] 2.7.3 Effect on reducing sugar content

[0099] The reducing sugar content was determined using the 3,5-dinitrosalicylic acid colorimetric method according to the NY / T 2742-2015 standard. A certain amount of lyophilized sample was weighed, diluted with deionized water, and 3,5-dinitrosalicylic acid reagent (DNS, Sigma-Aldrich, CAS Number: 609-99-4) was added. The mixture was boiled for 5 min, cooled, and brought to a final volume. The absorbance at 540 nm was measured using a spectrophotometer.

[0100] 2.7.4 Effect on lactic acid content

[0101] Referring to the national standard GB 5009.157-2016 method for detecting lactic acid content, accurately weigh 0.5 g of photocatalyzed corn syrup freeze-dried sample into a 5 mL centrifuge tube, add 2.0 mL of deionized water, and then take 1 mL of sample and filter it through a 0.22 µm filter membrane. The lactic acid content was detected by high performance liquid chromatography under the following conditions: mobile phase of 0.1% formic acid water-acetonitrile (volume ratio of 97.5:2.5) isocratic elution for 10 min, column temperature of 40℃, injection volume of 20 μl, and detection wavelength of 210 nm.

[0102] 2.7.5 Effect on odor:

[0103] Corn steep liquor samples with different photocatalytic treatment times (0 h, 8 h, 16 h, 24 h, 32 h, 40 h) were placed in sample vials for electronic noses, leaving about 1 / 2 volume empty. After sealing for 24 h, the odor characteristics of each corn steep liquor sample were detected using a PEN-3 electronic nose.

[0104] 3. Results and Analysis

[0105] 3.1 Degradation efficiency of NI-TiO2 composite photocatalyst with different N and I doping ratios for DON degradation

[0106] To investigate the effects of N and I doping on the degradation efficiency of DON, the degradation rates of DON by Ni-TiO2 with different N and I doping ratios were measured. Figure 1 As shown, in a 25 mL reaction system, the photocatalytic degradation efficiency of N and I-doped TiO2 was significantly higher than that of pure TiO2. Among them, the co-doped photocatalyst I(5%)-N(30%)-TiO2 exhibited the highest degradation efficiency for DON, with a degradation rate approaching 90% after 4 hours of treatment. This is 2.5 times and 1.53 times that of N(30%)-TiO2 and I(5%)-TiO2 under the same doping conditions. This is because co-doping leads to a synergistic effect between the two elements, reducing the band gap of TiO2, promoting the generation of photogenerated carriers, and thus enhancing the photocatalytic activity.

[0107] 3.2 Effects of different addition amounts and time on the degradation efficiency of DON by I(5%)-N(30%)-TiO2

[0108] The initial concentration of DON was 5 µg / mL. The effects of the amount of I(5%)-N(30%)-TiO2 photocatalyst and the degradation time on the efficiency of DON degradation are as follows: Figure 2 As shown, the degradation rate of DON initially increases and then decreases with increasing catalyst concentration. When the composite photocatalyst concentration is 5 mg / mL, the degradation rate of DON reaches 97.62% after 4 hours and is completely degraded after 6 hours. Increasing the photocatalyst concentration from 1 mg / mL to 5 mg / mL generates more electrons and holes, increases the number of active sites, and increases the number of free radicals that contribute to oxidation, thus improving the photocatalytic degradation efficiency. When the photocatalyst concentration exceeds 5 mg / mL, the excessive high concentration of IN-TiO2 particles aggregates, reducing the transmittance of the entire reaction system. This hinders the generation of more active substances, prevents full utilization of light energy, and decreases the photocatalytic degradation efficiency of DON.

[0109] 3.3 Recovery efficiency of composite photocatalyst I(5%)-N(30%)-TiO2

[0110] I(5%)-N(30%)-TiO2 in the photocatalytic reaction system was collected by centrifugation, washed with deionized water, dried, and its degradation efficiency for DON was analyzed. The results are as follows: Figure 3As shown, after three repeated uses of light, the degradation rates of DON were 96.25%, 91.95%, and 80.64%, respectively. Even after three repeated uses, the degradation rate of DON still reached over 80%. These results demonstrate that the composite photocatalyst can be reused and has good stability.

[0111] 3.4 Characterization and Analysis of Photocatalysts

[0112] 3.4.1 Morphology and Structure

[0113] Specific surface area and particle size play a crucial role in the photocatalytic performance of TiO2. A larger surface area and smaller particle size lead to an increase in the number of surface active sites, thus significantly improving photocatalytic efficiency. The morphology, structure, and particle size of TiO2, N(30%)-TiO2, I(5%)-TiO2, and I(5%)-N(30%)-TiO2 photocatalysts were analyzed using SEM and TEM. Figure 4 (a) It can be seen that the undoped TiO2 exhibits obvious agglomeration and compaction, which is consistent with... Figure 5 (a) The transmission electron microscopy results are consistent; the N(30%)-TiO2 photocatalyst after N element doping TiO2 has a uniform distribution, clear structure, and no obvious agglomeration phenomenon. Figure 4 b and Figure 5 b); The photocatalyst I(5%)-TiO2, after being doped with element I, effectively reduced the particle size of the photocatalytic nanoparticles ( Figure 4 (c and 3-5c) facilitate the movement of electrons from the interior of the structure to the surface. Figure 4 (d) It can be seen that, compared with undoped TiO2, I(5%)-N(30%)-TiO2 has a smaller average particle size and no obvious agglomeration phenomenon, consistent with transmission electron microscopy. Figure 5 The result of (d) is consistent, with an average grain size of less than 40 nm.

[0114] 3.4.2 Specific surface area and pore size distribution

[0115] As shown in Table 3-1, BET testing revealed that I(5%)-N(30%)-TiO2 nanoparticles have a larger specific surface area than undoped TiO2, which is 1.31 times larger. This is beneficial for improving the adsorption of DON in the solution and enhancing the adsorption-desorption process of the photocatalytic nanoparticles during photocatalytic degradation, thereby facilitating the photocatalytic degradation reaction.

[0116] Table 3-1 Crystal phases and specific surface areas of TiO2, N(30%)-TiO2 photocatalysts, I(5%)-TiO2 photocatalysts and I(5%)-N(30%)-TiO2 photocatalysts

[0117] sample <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[TiO2]]> 64.815 <![CDATA[N(30%)-TiO2]]> 59.378 <![CDATA[I(5%)-TiO2]]> 85.922 <![CDATA[I(5%)-N(30%)-TiO2]]> 84.886

[0118] 3.4.3 XRD Analysis

[0119] like Figure 6 As shown, the anatase characteristic diffraction peaks of each sample are clear and sharp, indicating good crystal stability. By comparing with the standard card of anatase TiO2 [JCPDS card: No. 84-1285], it was found that the diffraction peaks in the synthesized catalyst all correspond to the diffraction peaks of the anatase phase TiO2, and no rutile phase was observed. The characteristic peaks of TiO2 and Ni-TiO2 nanoparticles are basically consistent, and the characteristic peaks of anatase are observed at 2θ = 25.3°, 37.8°, 48.04°, 55.06°, 62.69°, and 68.76°, among which 2θ = 25.3° is the (101) crystal plane of anatase. After N or I doping TiO2, the intensity of each diffraction peak of the sample gradually decreases, which shows that N or I doping can effectively suppress the phase transformation and grain growth of TiO2. Even after calcination at a higher temperature, the sample still remains anatase TiO2. After N and I doping, the different charges and ionic radii will cause lattice distortion. XRD data show that the co-doping of N and I ions causes a certain degree of lattice distortion in TiO2, which suppresses the phase transition of TiO2 and allows TiO2 to maintain the photocatalytic activity of the anatase phase.

[0120] 3.4.4 FT-IR analysis

[0121] Various photocatalysts at 4000-400 cm -1 The FT-IR spectrum of the region, such as Figure 7 As shown. For all samples, 455.3 cm -1 The peak at 1607.3 cm⁻¹ is a characteristic peak caused by the strong tensile vibrations of Ti-O and Ti-O-Ti bonds. -1 The characteristic peak is attributed to the bending vibration of the OH bonds in adsorbed water molecules; 3418.4 cm⁻¹ -1 The peak is attributed to the stretching vibration of hydroxyl groups on the catalyst. Data for Ni-TiO2 shows a peak at 1324.9 cm⁻¹. -1 A new characteristic absorption peak was observed at 1385.8 cm⁻¹, which is a characteristic peak of the bending vibration of Ti-OI formed after I doping. Compared with other samples, I(5%)-N(30%)-TiO₂ shows a peak at 1385.8 cm⁻¹. -1 The peaks are caused by the vibrations of different Ti-OH surface groups. This band is a new absorption peak generated by the absorption of different Ti-OH surface groups, which have stronger hydrogen bonds with the adsorbed water molecules and are not affected by temperature increases. Co-doping of N and I increases the amount of water and hydroxyl groups adsorbed on the surface, which is beneficial to the photocatalytic process.

[0122] 3.4.5 UV-Vis Analysis

[0123] The UV-Vis spectra of each sample are as follows: Figure 8 As shown, pure TiO2 does not respond to visible light, while N and I co-doping extends the absorption of visible light. I(5%)-N(30%)-TiO2 nanoparticles show stronger absorption in the ultraviolet region compared to undoped TiO2, with a slight red shift in the absorption band, indicating enhanced response to visible light. This is because N atoms can replace Ti and O in the TiO2 lattice, increasing oxygen vacancies and enhancing absorption in both the ultraviolet and visible light regions. The presence of I-doped I-TiO2 in the visible light range is likely due to the presence of I... 5+ With Ti 4+ The ionic radii are similar, I 5+ Doping introduces lattice distortion, which alters the band gap. According to the Kubelka-Munk equation, the band gap of the I(5%)-N(30%)-TiO2 photocatalytic nanoparticles is calculated to be 2.67 eV, significantly reducing the band gap of TiO2. This results in a marked decrease in the energy required for electron transitions, a redshift of the photoresponse range towards the visible light spectrum, and promotes the photocatalytic activity of TiO2.

[0124] 3.5 DON degradation products

[0125] 3.4. TOC Analysis

[0126] During the photocatalytic degradation process, DON is decomposed into small molecule organic matter, which is gradually mineralized into CO2 and H2O as the photocatalytic time increases. Figure 9 The changes in DON content at an initial concentration of 5 µg / mL during the degradation of I(5%)-N(30%)-TiO2 and the changes in TOC content during photocatalysis are shown. As the photocatalytic degradation reaction proceeds, the DON concentration is positively correlated with the TOC content, indicating that more and more DON is further mineralized into CO2 and H2O. After 6 h of photocatalytic treatment, DON is completely degraded, with a TOC degradation rate of 95.08%. However, some organic carbon remains in the reaction system, further indicating that DON is not directly degraded into CO2 and H2O, but rather gradually degraded into a series of small-molecule organic compounds.

[0127] 3.4.3 DON degradation products

[0128] With increasing photocatalytic time, the degradation rate of DON gradually increased, reaching 100% after 20 hours of photocatalytic degradation. Figure 10 a). Total ion current chromatograms (TICs) of DON and photocatalytic degradation products were obtained by mass spectrometry analysis. Figure 10 b, Figure 10c) DON exhibits a characteristic peak at 1.47 min. After photocatalytic degradation, DON produces three product peaks at retention times of 0.6 min, 1.26 min, and 3.72 min. It is inferred that these three substances are products of DON via I(5%)-N(30%)-TiO2 photocatalyst, and are named products P1, P2, and P3, respectively.

[0129] To identify the molecular structures of P1, P2, and P3, the primary mass spectra of the three products were analyzed. Positive ion scanning yielded an m / z value of 297.14 for DON, and m / z values ​​for P1, P2, and P3 of 209.12, 227.13, and 318.11, respectively. The deduced molecular structures and formulas of P1, P2, and P3 are shown in Table 3-2 and [Table 3-2 is missing from the original text]. Figure 11 The molecular formula of P1 is C 12 H 16 O3; P2 has the molecular formula C 12 H 18 O4; P3 molecular formula C 17 H 18 O6. During photocatalysis, a large amount of ROS is generated, attacking the structure of DON, decomposing it, and reducing its toxicity. P1 and P2 are similar to products reported in previous studies. P2 is formed because free radicals generated by the composite photocatalyst during photocatalysis break the epoxy groups at the C12-C13 positions of DON, converting them into diene bonds. P1 is a product formed by further dehydration of P2. During the photocatalytic reaction, the CO bond at position 2 of DON is broken, forming an unstable six-membered ring intermediate, removing the five-membered ring and epoxy groups, thus reducing the toxicity of DON. Simultaneously, due to the instability of the intermediate, the two six-membered rings combine to form P3 through a dehydration reaction. These results indicate that the composite photocatalyst can oxidatively destroy multiple toxic structures of DON.

[0130] Table 3-2 Three DON degradation products identified by UPLC / Q-TOF / MS

[0131] complex Retention time (min) Molecular formula Theoretical molecular weight (m / z) DON 1.47 <![CDATA[C 15 H 20 O6]]> 297.1338 P1 0.6 <![CDATA[C 12 H 16 O3]]> 209.1178 P2 1.26 <![CDATA[C 12 H 18 O4]]> 227.1283 P3 3.72 <![CDATA[C 17 H 18 O6]]> 318.1103

[0132] 3.5 Cytotoxicity of I(5%)-N(30%)-TiO2 photocatalyst and DON photocatalytic degradation products

[0133] 3.5.1 Effects on cell morphology

[0134] Morphological changes of IPEC-J2 cells after treatment with different concentrations of I(5%)-N(30%)-TiO2 for 24 h are as follows: Figure 12As shown in the figure, the cells in the blank control group showed good growth, adhered well, had plump cell morphology, clear cell boundaries, and high cell density. When the concentration of I(5%)-N(30%)-TiO2 was low, the cell morphology remained basically intact. When the concentration was higher than 800 µg / mL, the number of cells began to decrease, the intercellular spaces widened, and the irregular cell morphology increased significantly. At the maximum concentration of 2000 µg / mL, many suspended dead cells appeared.

[0135] After IPEC-J2 cells were incubated with DON degradation products at different time points for 24 h via photocatalytic degradation, the morphological changes of the cells were as follows: Figure 13 As shown in the figure, IPEC-J2 cells in the blank CON group showed good growth, uniform distribution, and good intercellular connectivity. After 0 min of photocatalytic treatment (toxin concentration 5 µg / mL), the number of suspended dead cells increased, intercellular spaces widened, and irregular cell types increased, becoming elongated and needle-like. With increasing photocatalytic treatment time and decreasing DON concentration, the morphology of IPEC-J2 cells improved; the cell morphology in the 6 h degradation group was similar to that in the blank group.

[0136] 3.5.2 Effects on cell viability

[0137] like Figure 14 As shown, after incubating IPEC-J2 cells with different concentrations of I(5%)-N(30%)-TiO2 for 24 h, compared with the blank control group, the cell proliferation rate decreased with increasing I(5%)-N(30%)-TiO2 concentration, indicating that high concentrations of photocatalyst inhibit cell proliferation. Except for the 50 µg / mL experimental group, cytoplasmic proliferation was significantly inhibited in all other experimental groups (P < 0.05). The cell proliferation activity in the 50 µg / mL-800 µg / mL groups was above 80%, and the cell activity in the 2000 µg / mL group was 71.17%.

[0138] Depend on Figure 15 It was observed that the relative cell proliferation rate gradually increased after photocatalytic degradation for 0 h, 1 h, 2 h, and 4 h (P < 0.05). After 4 h of photocatalytic degradation, the relative cell proliferation rate reached over 95%, indicating that the DON catalytic degradation products had very low toxicity to cells, which is consistent with the above analysis of organic carbon content. After 6 h of photocatalytic degradation, the relative cell proliferation rate was not significantly different from the control group (P > 0.05), indicating that the toxicity of DON had been completely eliminated.

[0139] 3.5.4 Effects on apoptosis

[0140] like Figure 16As shown, the fluorescence intensity of the I(5%)-N(30%)-TiO2 group at different concentrations gradually increased, but the overall fluorescence intensity was weak, and the red fluorescence was significantly weaker than the green fluorescence, indicating that the composite photocatalyst can cause early cell apoptosis at low concentrations; when the concentration was below 800 μg / mL, no obvious toxic effect was observed.

[0141] Figure 17 This study investigated the apoptosis of IPEC-J2 cells 24 h after treatment with DON degradation products at different photocatalytic degradation times. Compared to the control group, the fluorescence intensity of each experimental group gradually decreased with increasing DON degradation time, corresponding to a decrease in the early and late stages of cell apoptosis. This indicates that the toxicity of the degradation products gradually decreases with increasing photocatalytic time. After 4 h of photocatalytic degradation, almost no fluorescence was observed, similar to the results of the control group.

[0142] 3.6 Detoxification effect of I(5%)-N(30%)-TiO2 on DON in corn steep liquor

[0143] Photocatalytic treatment of corn steep liquor solutions containing DON for different durations was performed, and the results are as follows: Figure 18 As shown, with the extension of photocatalytic time, the degradation rate of DON increased significantly compared with the 0h group (P < 0.05), and the degradation rate was 71.72% at 40h.

[0144] 3.7 Effect of I(5%)-N(30%)-TiO2 on the quality of corn steep liquor

[0145] 3.7.1 Effect on protein content in corn steep liquor

[0146] Corn steep liquor is rich in soluble nutrients from corn, making it highly nutritious and valuable. Its nutritional components include soluble protein, lactic acid and sugars, various amino acids, and trace elements, with protein accounting for over 70% of its dry matter. Figure 19 As shown, with the extension of light exposure time, the protein content of the control group and the photocatalytic degradation groups at 8 h, 16 h and 24 h did not change significantly (P > 0.05). After 32 h and 40 h of photocatalytic degradation, the protein content decreased significantly (P < 0.05), but compared with the control group, the protein content decreased by 2.80% and 3.55%, respectively, indicating that the use of I(5%)-N(30%)-TiO2 had little effect on the protein content in DON-contaminated corn steep liquor.

[0147] 3.7.2 Effect on amino acid content in corn steep liquor

[0148] Table 3-3 shows the changes in the amino acid content in corn steep liquor after 0 h of photocatalytic degradation and after 40 h of photocatalytic degradation. Compared with the untreated group, the contents of Cys, Tyr, and His decreased significantly after 40 h of photocatalytic degradation (P < 0.05), by 33.56%, 26.99%, and 25.94%, respectively. This is mainly because the strong oxidizing groups generated by I(5%)-N(30%)-TiO2 under xenon lamp irradiation also oxidize some amino acids. The total amount of essential amino acids and the total amino acid content did not change significantly (P > 0.05).

[0149] Table 3-4 Effects of composite photocatalysts on amino acid content in corn steep liquor

[0150] amino acids 0 h (mg / g) 40 h (mg / g) Asp 35.27±0.51 34.83±1.25 Thr 13.91±0.16 13.96±0.47 Ser 19.48±0.14 19.10±0.65 Glu 78.98±1.08 80.04±2.76 Gly 119.47±2.36 112.77±1.89 Ala 33.01±0.77 28.68±1.33 Cys <![CDATA[1.46±0.01 a ]]> <![CDATA[0.97±0.02 b ]]> Val 17.68±0.21 17.44±0.66 Met 5.82±0.06 5.72±0.25 Ile 10.87±0.11 10.84±0.38 Leu 25.88±0.30 26.23±0.96 Tyr <![CDATA[4.89±0.12 a ]]> <![CDATA[3.57±0.10 b ]]> Phe 13.57±0.30 13.66±0.57 Lys 21.63±0.29 21.57±0.80 NH3 6.50±0.32 5.94±0.04 His <![CDATA[6.31±0.06 a ]]> <![CDATA[4.67±0.19 b ]]> Arg 42.28±0.54 41.62±1.51 Pro 132.41±3.42 128.98±4.70 EAA 109.36±1.43 106.55±5.93 TAA 598.87±6.15 570.60±7.50

[0151] Note: The same letter or no letter in the same row of labels indicates no significant difference (P>0.05), while different letters indicate a significant difference (P<0.05).

[0152] 3.7.3 Effect on the reducing sugar content in corn steep liquor

[0153] Corn steep liquor is typically concentrated to a water content of around 50% before use. The concentrated corn steep liquor is viscous, and at this water content, it contains approximately 10% reducing sugars. The reducing sugar content has a significant impact on the microbial cultivation process. For example... Figure 20 As shown, the content of reducing sugar in corn steep liquor in the untreated corn steep liquor group (0 h) and each experimental group was not significantly different (P > 0.05), so the content of reducing sugar in corn steep liquor will not be significantly affected by the I(5%)-N(30%)-TiO2 photocatalysis process.

[0154] 3.7.4 Effect on pH value of corn steep liquor solution

[0155] like Figure 21 As shown, compared with the untreated corn steep liquor sample (0 h), the pH of the corn steep liquor in each experimental group only increased from 5.32 to 5.35 with the increase of photocatalytic treatment time, and the change between groups was not significant (P>0.05).

[0156] 3.7.5 Effect on lactic acid content in corn steep liquor

[0157] Lactic acid, as a small organic molecule, has a simpler structure compared to DON molecules. In a DON-containing corn steep liquor solution, during the photocatalytic reaction, the highly reactive groups generated by the photocatalysis also oxidize lactic acid molecules, leading to their degradation. Figure 22Compared with the control group (0 h), the lactic acid content in each experimental group was significantly reduced at 8 h, 16 h, 24 h, 32 h and 40 h of photocatalytic degradation (P < 0.05), reaching the lowest level after 40 h of photocatalytic degradation, with a lactic acid degradation rate of 52.55%.

[0158] 3.7.6 Effect on the odor of corn steep liquor

[0159] The changes and distribution of odor in corn steep liquor after I(5%)-N(30%)-TiO2 photocatalytic treatment are as follows: Figure 23 As shown, compared with the control group, the odor of the corn steep liquor sample generally increased with the increase of photocatalytic treatment time (P > 0.05). After 40 h of photocatalytic reaction, the odor intensity of long-chain alkanes (W3S) and nitrogen oxides (W5S) was the highest, while the substances reflected by other sensors did not increase significantly. This is mainly due to the decomposition of organic matter such as toxin molecules and proteins during the photocatalytic reaction.

Claims

1. A method for preparing an iodine- and nitrogen-co-doped TiO2 photocatalyst for degrading the mycotoxin DON, characterized in that... The preparation method of the iodine and nitrogen co-doped TiO2 photocatalyst for degrading mycotoxin DON is as follows: Solution A was prepared by dissolving 10 mL of tetrabutyl titanate and 3 mL of acetic acid in 20 mL of anhydrous ethanol. Solution B was prepared by dissolving urea in 4 mL of water. Solution C was prepared by dissolving potassium iodate in 4 mL of water. Solutions B, C and A were mixed and stirred until the solution became a sol and then a gel. The gel was allowed to stand for 24 h, dried at 80 °C, ground and calcined at 400 °C for 2 h to obtain the photocatalyst.

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