Application of Fe / C composite material combined with Shewanella Oneida in degradation of pesticide malathion

Abstract

This invention provides the application of Fe / C composite material combined with *S. wanandii* in the degradation of the pesticide malathion, belonging to the field of pesticide degradation technology. This invention provides the application of *S. wanandii* in the degradation of the pesticide malathion, offering a new method for the biodegradation of malathion. This invention also provides a material for degrading the pesticide malathion, comprising an Fe / C composite material and *S. wanandii* loaded within the pores of the Fe / C composite material. The porous structure of the Fe / C composite material serves as a habitat for *S. wanandii*. Scanning electron microscopy reveals clusters of deposits on the spiral vessels of the Fe / C composite material, within the vascular bundles, and within the pits on the radial and transverse walls of the fibrous cell cavities. *S. wanandii* colonizes and grows within these pores, and the Fe / C composite material enhances the degradation of malathion by *S. wanandii*.

Description

Technical Field

[0001] This invention belongs to the field of pesticide degradation technology, specifically involving the application of Fe / C composite material combined with Oneidashewara bacteria in the degradation of the pesticide malathion. Background Technology

[0002] Malathion, an organophosphorus pesticide, is one of the most common insecticides. Its persistence in aquatic environments poses a serious threat to human health and ecosystems. Currently, malathion treatment methods can be categorized into chemical, physical, and biological methods. Chemical methods, specifically chemical oxidation, utilize the strong oxidizing properties of chemical oxidants to decompose pollutants in water. Commonly used oxidants include ozone and chlorine dioxide. Advanced oxidation processes (AORs), characterized by the generation of reactive free radicals, can be used for the decomposition and mineralization of organic pollutants and are an effective pesticide removal method. Physical methods mainly include membrane separation, sand filtration, and adsorption. Among these methods, adsorption is considered an environmentally friendly technology due to its low implementation cost, simple application, and good removal efficiency. Biological methods primarily use microorganisms to eliminate pollutants in the environment. Compared to physical and chemical methods, biological methods are a benign approach to removing malathion, offering environmental safety, cost-effectiveness, and public acceptance. Microorganisms can metabolically decompose malathion using both enzymatic and non-enzymatic reactions, a process with advantages such as thorough degradation and mild reaction. In recent years, the technology of using bacteria, fungi and other microorganisms in water for the degradation of malathion has been widely developed and applied.

[0003] However, there are currently no reports on the degradation of the pesticide malathion by *Schizophyllum heliotropium* or Fe / C composite materials combined with *Schizophyllum heliotropium*. Summary of the Invention

[0004] The purpose of this invention is to provide the application of *Schizophyllum onyx* or Fe / C composite material combined with *Schizophyllum onyx* in the degradation of the pesticide malathion. This invention provides a new method for the biodegradation of the pesticide malathion.

[0005] This invention provides the application of *Hemibarbus onyx* in the degradation of the pesticide malathion.

[0006] The present invention also provides a material for degrading the pesticide malathion, comprising an Fe / C composite material and Onedashiwab loaded within the pores of the Fe / C composite material.

[0007] Preferably, the preparation method of the Fe / C composite material includes the following steps:

[0008] Bamboo and ammonia water are mixed and boiled. The boiled bamboo is then washed and dried to obtain the first dry bamboo.

[0009] The first dried bamboo is mixed with ferric nitrate solution and soaked. The soaked bamboo is then dried to obtain the second dried bamboo.

[0010] The second dried bamboo was roasted and cooled to obtain the Fe / C composite material.

[0011] Preferably, the ferric nitrate solution uses a mixture of ethanol and water as a solvent; the volume ratio of ethanol to water in the mixture is 1:1.

[0012] Preferably, the roasting temperature is 600°C and the roasting time is 3 hours.

[0013] Preferably, the material further includes a culture for culturing Oneida Shewanella.

[0014] The present invention also provides the application of the material described in the above scheme in the degradation of the pesticide malathion.

[0015] This invention also provides the application of Fe / C composite materials in combination with *Hemibarbus onyx* in the degradation of the pesticide malathion.

[0016] This invention also provides a method for degrading the pesticide malathion, comprising the following steps:

[0017] Apply *Shewanella onyx* to the sample containing malathion to initiate degradation; or...

[0018] The material described in the above scheme is applied to the sample containing malathion to carry out degradation; or,

[0019] The Fe / C composite material and Herwaxone onedida were mixed and applied to the sample containing malathion to be degraded, and the degradation was carried out.

[0020] Preferably, the pH of the degradation is 6 to 8; and the temperature of the degradation is 30 to 35°C.

[0021] This invention provides the application of *S. onenaeidae* in the degradation of the pesticide malathion. *S. onenaeidae* achieves a degradation efficiency of 53.38% for malathion, providing a novel method for the biodegradation of malathion. This invention also provides a material for degrading malathion, comprising an Fe / C composite material and *S. onenaeidae* loaded within the pores of the Fe / C composite material. The porous structure of the Fe / C composite material serves as a habitat for *S. onenaeidae*. Scanning electron microscopy reveals clusters of deposits on the spiral vessels of the Fe / C composite material, within the vascular bundles, and within the pits on the radial and transverse walls of the fibrous cell cavities. *S. onenaeidae* colonizes and grows within these pores, and the Fe / C composite material enhances the degradation of malathion by *S. onenaeidae*. It has been verified that in a system with a malathion concentration of 10 mg / L, the degradation efficiency of malathion by Herwatella onedida malignancies Mr-1 loaded into the pores of the Fe / C composite material can reach 98.01%. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 SEM images of Fe / C composite material + Herwatella onedina MR-1 before and after degradation of malathion, including (A) the prepared Fe / C composite material, (B) the bacterial cells, the degraded Fe / C composite material (D) and its magnified part (E), and the EDS spectra of the Fe / C composite material before (C) and after (F) degradation.

[0024] Figure 2 The images show the nitrogen adsorption / desorption isotherms (A) and pore size distribution (B) of the Fe / C composite material at liquid nitrogen temperature.

[0025] Figure 3 XRD patterns of Fe / C composite material + Oneida Shewanella MR-1 before and after degradation of malathion;

[0026] Figure 4 FTIR spectra of Fe / C composite material + *Schizophyllum onyx* MR-1 before and after degradation of malathion;

[0027] Figure 5 XPS spectra of Fe / C composite material + Oneda Shewanella MR-1 before and after degradation of malathion;

[0028] Figure 6This indicates the effect of inoculum size on the degradation of malathion;

[0029] Figure 7 This indicates the effect of pH on the degradation of malathion by *Hemibarbus ononidas*.

[0030] Figure 8 This indicates the effect of temperature on the degradation of malathion by *Hemibarbus onyx*.

[0031] Figure 9 The effect of Fe / C composite material addition on the degradation of malathion by *Schizophyllum ononida* MR-1 is indicated. Detailed Implementation

[0032] This invention provides the application of *Hemibarbus onyx* in the degradation of the pesticide malathion.

[0033] In this invention, *Hemibarbus onyx* transfers electrons through extracellular respiration, reducing Fe(III) iron oxide to Fe(II). Fe(II) possesses a certain redox capacity, and during the degradation process, the coupled microorganisms promote the degradation of malathion.

[0034] In this invention, the *S. oneidensis* is *S. oneidensis* MR-1. In this invention, the *S. oneidensis* MR-1 was purchased from the China Marine Microbiological Culture Collection Center (MCCC), with accession number ATCC 700550. The *S. oneidensis* MR-1 is slender, rod-shaped.

[0035] The present invention also provides a material for degrading the pesticide malathion, comprising an Fe / C composite material and Onedashiwab loaded within the pores of the Fe / C composite material.

[0036] In this invention, the iron in the Fe / C composite material exists in the form of oxides; the Fe / C composite material is preferably the undersize component of a 100-mesh sieve.

[0037] In this invention, the preferred method for preparing the Fe / C composite material includes the following steps:

[0038] Bamboo is mixed with ammonia water and boiled. The boiled bamboo is then washed and dried to obtain first dried bamboo. The first dried bamboo is mixed with ferric nitrate solution and soaked. The soaked bamboo is then dried to obtain second dried bamboo. The second dried bamboo is then calcined and cooled to obtain Fe / C composite material.

[0039] The present invention first mixes bamboo with ammonia water and boils it, then washes and dries the boiled bamboo to obtain the first dried bamboo.

[0040] In this invention, the bamboo is preferably waste bamboo from the bamboo processing industry; the bamboo is preferably bamboo blocks; the dimensions of the bamboo blocks are preferably 30mm × 10mm × 3mm. In this invention, the ammonia water is preferably dilute ammonia water; the mass concentration of the ammonia water is preferably 5%; in this invention, the boiling temperature is preferably 100℃; the boiling time is preferably 6 hours; the purpose of boiling is to change the structure of the bamboo material, facilitating subsequent loading; the drying is preferably electric heating with forced air drying; the drying temperature is preferably 80℃; the drying time is preferably 24 hours.

[0041] After obtaining the first dried bamboo, the present invention mixes the first dried bamboo with ferric nitrate solution, soaks it, and then dries the soaked bamboo to obtain the second dried bamboo.

[0042] In this invention, the ferric nitrate solution preferably uses a mixture of ethanol and water as a solvent; the volume ratio of ethanol to water in the mixture is preferably 1:1. In this invention, the concentration of ferric nitrate in the ferric nitrate solution is preferably 1.2 mol / L; the ferric nitrate solution is a ferric nitrate precursor solution, used as the active component solution for impregnation; in this invention, the soaking temperature is preferably 60°C; the soaking time is preferably 5 days; the soaking process preferably involves water bath insulation; the drying is preferably electric heating drying; the drying temperature is preferably 80°C; and the drying time is preferably 24 hours.

[0043] After obtaining the second dried bamboo, the present invention roasts and cools the second dried bamboo to obtain the Fe / C composite material.

[0044] In this invention, the roasting temperature is preferably 600°C; the roasting time is preferably 3 hours; and the roasting is preferably carried out in a muffle furnace.

[0045] In this invention, the temperature after cooling is preferably 20-30°C, more preferably 25°C.

[0046] After cooling, the present invention preferably further includes grinding and sieving the cooled material in sequence; the screen mesh size for sieving is preferably 100 mesh.

[0047] In this invention, the Fe / C composite material is a porous material with a predominantly mesoporous structure and a hierarchical porous structure. Therefore, it possesses a large specific surface area, a porous structure, and a strong affinity for microorganisms, making it suitable as a habitat for microorganisms. In this invention, the abundant pores of the Fe / C composite material provide a suitable growth environment for *Shewanella onychomycosis*. Aggregates of deposits are visible on the spiral vessels of the Fe / C composite material, within the hoof canals of the vascular bundles, and within the radial and transverse walls of the fibrous cell cavities. *Shewanella onychomycosis* colonizes and grows within these pores. The Fe / C composite material is rich in Fe. Furthermore, *Shewanella onychomycosis* is a dissimilar metal-reducing bacterium, and the Fe / C composite material can promote electron transfer in *Shewanella onychomycosis*, thereby improving pesticide degradation efficiency.

[0048] In this invention, the material preferably further includes a culture for culturing *S. onenedashewanella* in the degradation system; the culture for culturing *S. onenedashewanella* is preferably an inorganic salt culture medium. In this invention, the inorganic salt culture medium uses water as a solvent and preferably comprises the following components at the following concentrations: KH₂PO₄ 0.5 g / L, K₂HPO₄ 0.5 g / L, (NH₄)SO₄ 2.5 g / L, Na₂SO₄ 1.0 g / L, CaCl₂ 0.1 g / L, MgSO₄ 1.0 g / L, NaCl 10 g / L, and trace element solution 1 mL / L; the trace element solution preferably uses water as a solvent and comprises the following components at the following concentrations: CoCl₂·6H₂O 0.1 g / L, MnSO₄·H₂O 0.01 g / L, ZnCl₂ 0.05 g / L, NiCl₂·6H₂O 0.01 g / L, CuSO₄·5H₂O 0.015 g / L, and Na₂MoO₄·2H₂O 0.001 g / L.

[0049] In this invention, the preferred method for preparing the material includes the following steps:

[0050] The Fe / C composite material was mixed with the bacterial solution of *Hemibarbus onyx* to obtain a material that degrades the pesticide malathion.

[0051] In this invention, the OD of the bacterial suspension of *Heliotropium onychomycosis* is... 600 The preferred value is 1.

[0052] In this invention, the bacterial culture of *Heliotropium onychomycosis* is preferably prepared by the following method:

[0053] Onenaeida Shewanella strains were streaked onto LB solid medium for activation culture until colonies grew on the solid medium; single colonies of Onenaeida Shewanella were then inoculated onto LB liquid medium for expansion culture to obtain Onenaeida Shewanella bacterial suspension.

[0054] In this invention, the activation culture temperature is preferably 30°C; the activation culture rotation speed is preferably 160 rpm; and the activation culture time is preferably 48 h.

[0055] In this invention, the temperature of the expansion culture is preferably 30°C; the rotation speed of the expansion culture is preferably 160 rpm; and the expansion culture time is preferably 16 h.

[0056] After the expansion culture, the present invention preferably further includes centrifuging the expanded culture, collecting the precipitate, washing and resuspending the precipitate; the centrifugation speed is preferably 6000 rpm; the centrifugation time is preferably 5 min; the washing reagent is preferably PBS buffer solution; the washing is preferably performed 3 times; the resuspension reagent is preferably inorganic salt culture medium.

[0057] The present invention also provides the application of the material described in the above scheme in the degradation of the pesticide malathion.

[0058] This invention also provides the application of Fe / C composite materials in combination with *Hemibarbus onyx* in the degradation of the pesticide malathion.

[0059] This invention also provides a method for degrading the pesticide malathion, comprising the following steps:

[0060] Apply *Shewanella onyx* to the sample containing malathion to initiate degradation; or...

[0061] The material described in the above scheme is applied to the sample containing malathion to carry out degradation; or,

[0062] The Fe / C composite material and the bacterial solution of *Schizophyllum heliostatus* were mixed and applied to the sample containing malathion to be degraded, and the degradation was carried out.

[0063] In this invention, the pH of the degradation is preferably 6 to 8; the temperature of the degradation is preferably 30 to 35°C.

[0064] In this invention, the working concentration of the Fe / C composite material is preferably 0.1–0.4 g / L, more preferably 0.2–0.3 g / L; in this invention, the OD of the bacterial culture of *Schizium anisopliae* is... 600 Preferably, the concentration is 1; the working concentration of the *Schizophyllum heliostatus* culture is preferably 10% by volume.

[0065] To further illustrate the present invention, the application of the Fe / C composite material provided by the present invention in combination with *Hemibarbus onyx* in the degradation of the pesticide malathion is described in detail below with reference to the accompanying drawings and embodiments. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0066] The inorganic salt culture medium used in this embodiment uses water as a solvent and consists of the following components at the following concentrations: KH2PO4 0.5 g / L, K2HPO4 0.5 g / L, (NH4)SO4 2.5 g / L, Na2SO4 1.0 g / L, CaCl2 0.1 g / L, MgSO4 1.0 g / L, NaCl 10 g / L, and trace element solution 1 mL / L; the trace element solution uses water as a solvent and consists of the following components at the following concentrations: CoCl2·6H2O 0.1 g / L, MnSO4·H2O 0.01 g / L, ZnCl2 0.05 g / L, NiCl2·6H2O 0.01 g / L, CuSO4·5H2O 0.015 g / L, and Na2MoO4·2H2O 0.001 g / L.

[0067] Example 1

[0068] 1. Preparation method:

[0069] (1) Activation of bacterial strain: Onedashewanella MR-1 was stored in a glycerol tube at -80℃. It needs to be activated before use. The thawed bacterial strain was streaked onto LB solid medium and cultured at 30℃ and 160 rpm for 48 h. When bacteria grow on the solid medium, it indicates that the strain has been successfully activated and can be used for subsequent experiments.

[0070] (2) Preparation of bacterial suspension: Before conducting the anaerobic degradation experiment, it is necessary to expand the culture of the bacterial strain. Activated *Shewanella onedida* MR-1 was transferred to LB liquid medium and cultured continuously at 160 rpm for 16 h at 30 °C. After completion, the culture was centrifuged at 6000 rpm for 5 min, washed three times with PBS buffer, and resuspended in inorganic salt medium. After diluting the bacterial suspension to a certain concentration, the absorbance (OD) was measured at 600 nm using a spectrophotometer. 600 Formulated into OD 600 The bacterial suspension with a concentration of 1 was placed in a refrigerator at 4°C for later use.

[0071] The Fe / C composite material used in this embodiment is prepared using the following specific method:

[0072] (1) After drying the waste bamboo from the bamboo processing industry, cut it into small pieces (about 30mm×10mm×3mm), add 5% dilute ammonia water and boil for 6 hours, then rinse it clean and dry it in an 80℃ electric heating drying oven for 24 hours.

[0073] (2) Equal volumes of ethanol and ultrapure water were mixed to prepare a solvent. Ferric nitrate was used as a solute to prepare a 1.2 mol / L ferric nitrate precursor solution. This solution was used to soak the bamboo in the above operation (1). The bamboo was kept in a water bath at 60°C for 5 days. Then it was taken out and dried in an electric heating drying oven at 80°C for 24 hours.

[0074] (3) Repeat the above operation (2) 3 times. The resulting bamboo is roasted in a muffle furnace at 600℃ for 3 hours. After cooling, it is ground and sieved to obtain the Fe / C composite material.

[0075] Pretreatment for Instrumental Analytical Methods for Determining Malathion Concentration

[0076] To detect the residual malathion concentration in the samples during the experiment, samples were taken periodically, and liquid-liquid extraction was used to pretreat the samples as follows:

[0077] After centrifuging the sample, take 20 mL of the supernatant, add 20 mL of petroleum ether, and vortex vigorously (2500 rpm, 10 min). Let it stand until it separates into layers, then take 5 mL of the upper organic phase, blow it with nitrogen until it is almost dry, dissolve it in methanol, and make up to 5 mL. Take 2 mL of the methanol into a brown sample vial for testing.

[0078] Instrumental analytical methods for detecting malathion concentration

[0079] The content of malathion was determined by gas chromatography: column: Agilent DB-35MS (30m×320μm×0.25μm), pressure: 11psi, N2 flow: 1.6mL / min; FPD detector was used, temperature: 250℃, injection port temperature: 200℃, H2 flow: 100mL / min, air flow: 130mL / min, N2 flow: 30mL / min; column oven: 150℃, hold for 1 min; increase to 200℃ at 10℃ / min, hold for 1 min; increase to 260℃ at 5℃ / min, hold for 1 min; injection volume: 0.5μL.

[0080] Using a degradation system of 50 mL, *Onedashewanella foenum-1* bacterial suspension (OD600 = 1) and malathion were added to an inorganic salt culture medium. The bacterial suspension accounted for 10% of the total volume, and the final concentration of malathion was 10 mg / L. Under unloaded conditions, the degradation efficiency of *Onedashewanella foenum-1* for the pesticide malathion was only 53.38%.

[0081] The working concentration of Fe / C was 0.2 g / L. One-naïve Shewanella Mr-1 bacterial suspension with OD600 = 1 was mixed with the Fe / C composite material to load One-naïve Shewanella Mr-1 into the pores of the Fe / C composite material. This mixture was then added to an inorganic salt culture medium, and malathion was added to a final concentration of 10 mg / L. The degradation efficiency of the pesticide malathion by One-naïve Shewanella Mr-1 loaded onto the Fe / C composite material reached 98.01%.

[0082] Characterization analysis of Fe / C material samples before and after degradation

[0083] 1. SEM-EDS Analysis

[0084] Figure 1 (A) in the figure represents the prepared Fe / C composite material, which has a porous hierarchical structure. The abundant pores provide a suitable growth environment for Shewanella onedinae MR-1. Figure 1 (B) is an electron micrograph of Oneida Shewanella MR-1. It can be seen that Oneida Shewanella MR-1 is slender rod-shaped and relatively densely and evenly distributed on the carbon electrode sample. Figure 1 (D) in the figure represents a Fe / C composite material containing Oneda Shewanella MR-1 after degradation of malathion. Figure 1 E in the image is a magnified view of a local area. The electron micrograph after degradation shows that there are clumps of deposits on the spiral vessels of the Fe / C composite material, inside the hoof tubes of the vascular bundles, and in the pits on the radial and transverse walls of the fiber cell cavities. Oneydahia MR-1 colonizes and grows in these pores. Figure 1 (C) and (F) are the EDS spectra of the Fe / C composite material before and after degradation. It can be seen that the prepared Fe / C composite material contains abundant Fe, and the Fe content decreases after degradation, indicating that some Fe enters the solution of the degradation system.

[0085] 2. BET Analysis

[0086] The specific surface area, pore size, and pore volume of the Fe / C composite material were determined using the BET and BJH methods with a fully automated rapid specific surface area and porosity analyzer. The specific surface area was found to be 179.3530 m². 2 / g, with an average pore size of 7.8127nm and an average pore volume of 0.1038cm³. 3 / g. Figure 2 Image (A) shows the nitrogen adsorption-desorption isotherm of the Fe / C composite material at liquid nitrogen temperature. According to the IUPAC classification, the isotherm is type IV in shape and exhibits a type H3 hysteresis loop, which is related to the well-developed mesoporous structure. Figure 2As shown in pore size distribution diagram (B), the pore sizes of the Fe / C composite material are mainly concentrated at 3.7 nm (mesopores) and 9.9 nm (mesopores). These results indicate that the Fe / C composite material is a porous material dominated by mesopores, which is consistent with the porous structure observed on the surface of the Fe / C composite material in its SEM analysis. Due to its large specific surface area, porous structure, and strong affinity for microorganisms, the Fe / C composite material can serve as a habitat for microorganisms.

[0087] 3. XRD Analysis

[0088] The XRD results of *Schistosoma onychomycosis* MR-1 before and after degradation of malathion by adding Fe / C composite material are as follows: Figure 3 As shown, the Fe / C composite material surface is loaded with oxides such as Fe2O3 and Fe3O4. After degradation, the characteristic peaks of Fe2O3 at 2θ of 24.14°, 35.65°, 40.93°, 49.43°, 54.16°, 62.57°, and 64.10° are weakened, while the characteristic peak of Fe3O4 at 2θ of 30.27° is significantly enhanced. This indicates that the crystal form of iron oxide changes after degradation. It is speculated that this is because the iron oxide is reduced. Shewanella onedina MR-1 transfers electrons through extracellular respiration, reducing Fe(III) of iron oxide to Fe(II). Fe(II) has a certain redox ability, and the coupled microorganisms promote the degradation of malathion during the degradation process.

[0089] The addition of Fe / C composite material enhances the degradation of malathion by *S. oneeydashewanella*. The Fe / C composite material promotes the connection between electron donors, electron shuttles, and electron acceptors, thereby improving electron transfer efficiency and significantly increasing the degradation capacity of *S. oneeydashewanella* for malathion. Studies on the electron transfer pathway of *S. oneeydashewanella* MR-1 during the degradation process show that the degradation of malathion by the Fe / C composite-loaded *S. oneeydashewanella* system mainly relies on extracellular reduction. The interconversion between Fe(III) and Fe(II) on the Fe / C composite material, coupled with microbial growth and metabolism, promotes the degradation of malathion.

[0090] 4. FTIR analysis

[0091] Fourier transform infrared spectroscopy (FTIR) is a technique for analyzing the composition of substances through polar bond vibrations. It is an important method for material characterization and can be used for qualitative analysis of samples. The FTIR spectra of Fe / C composite reinforced *Schizium anisopliae* MR-1 before and after degradation of malathion are shown below. Figure 4 As shown. At 3435.03cm -1 The relatively broad absorption peaks correspond to the stretching vibration peaks of -OH (H2O and C-OH), at 536.97 and 464.61 cm⁻¹. -1The vibrational peaks at 1146.88 and 1115.86 cm⁻¹ are attributed to the Fe-O / Fe-OH vibration. After degradation, the peaks are at 1146.88 and 1115.86 cm⁻¹. -1 A small shoulder peak appeared nearby, corresponding to the in-plane stretching vibration of the CN bond. This is likely due to the presence of nitrogen introduced by bacterial cells in the Fe / C composite material; 1008.09cm -1 The peak values ​​at these locations correspond to the stretching vibrations of the PO bond; simultaneously, 536.97 and 464.61 cm⁻¹... -1 The intensity of the Fe-O / Fe-OH vibration peak at the site decreased significantly, indicating that Fe participated in the degradation process of malathion. It is speculated that Fe mediated the electron transfer of Oneda Shewanella MR-1.

[0092] 5. XPS Analysis

[0093] XPS analysis was used to characterize the Fe / C composite material before and after degradation, exploring the mechanism by which the Fe / C composite material enhances the degradation mechanism of malathion by *Schizophyllum demersum* MR-1. The full spectrum of the Fe / C composite material is shown in the image. Figure 5 In the spectrum (A), the peaks at 284.03, 529.35, and 709.99 eV correspond to the characteristic peaks of C1s, O 1s, and Fe 2p, respectively. The full spectrum after degradation (...) Figure 5 In (B) of the study, a P 2p characteristic peak was found at a binding energy of 132.74 eV, indicating that the Fe / C composite material surface contains P element, which is the result of the action of malathion.

[0094] Peak fitting diagram of C1s in Fe / C composite material ( Figure 5 The (C) spectrum shows spectral peaks of CC / C=C (284.80 eV), CO (286.45 eV), and C=O (288.73 eV). Compare... Figure 5 The peak intensities of (C) and (D) in the curves show a significant decrease after degradation of CC / C=C. The peak fitting diagram of O1s in the Fe / C composite material is shown. Figure 5 The spectrum (E) shows peaks for Fe-O (529.80 eV), Fe-OC / C=O (531.55 eV), and CO (533.01 eV). Compare... Figure 5 In the curves (E) and (F), after degradation, the peak intensities of Fe-O and CO decreased significantly, while the peak intensities of Fe-OC / C=O increased considerably, and the CO peak position shifted. Figure 5 As shown in (G), the peaks at 709.87, 711.46, 713.72, and 717.1 eV belong to satellite peaks of FeO, FeOOH, Fe3O4, and Fe(III), respectively. After degradation ( Figure 5In the (H) peaks, these peaks shift towards higher binding energies, indicating an increase in binding energy. This suggests that Fe participates in the chemical reaction after the reaction, with Fe atoms acting as electron acceptors and receiving electrons from the outside. These electrons are transferred to Fe(III) via the Mtr pathway of *Schizium anisopliae* MR-1, where Fe(III) is reduced to Fe(II), mediating the degradation of malathion.

[0095] Test Example 1

[0096] In this experiment, *Schizium anisopliae* MR-1 was selected as the test strain. Under anaerobic conditions, the effects of inoculum size, pH, and temperature on the removal efficiency of malathion were investigated. Under optimal degradation conditions, the degradation effect of Fe / C material combined with *Schizium anisopliae* MR-1 on malathion was analyzed. The degradation products were identified, and possible degradation pathways were inferred.

[0097] 1. Effects of different inoculum sizes on the degradation of malathion

[0098] (1) Test scheme

[0099] Using sterile inorganic salt culture medium as background electrolyte, OD 600 =1 WT and OT strains were inoculated into 50 mL culture systems at inoculation amounts of 2% (1 mL), 6% (3 mL), 10% (5 mL), 14% (7 mL), and 20% (10 mL), respectively. The malathion concentration was set at 10 mg / L, the pH was adjusted to 7, nitrogen was purged for deoxygenation, and the cultures were sealed with butyl rubber stoppers. The cultures were incubated at 35 °C and 160 rpm, and samples were taken periodically. After extraction, the malathion concentration was determined.

[0100] (2) Discussion of Results

[0101] Inoculum size is considered a key factor in the success of microbial degradation of pesticides or bioremediation of pesticide-contaminated areas. The effect of different inoculum sizes of *Onedashewanella MR-1* wild-type strain on malathion degradation is shown in [reference needed]. Figure 6 At lower inoculum levels, the concentration of *Onedashewanella MR-1* in the environment is correspondingly lower, which is unfavorable for the degradation of malathion by *Onedashewanella MR-1*; from Figure 6As can be seen, the degradation rate of malathion varied with the inoculum size of *Shewanella onychomycosis* MR-1 at 2% (1 mL), 6% (3 mL), 10% (5 mL), 14% (7 mL), and 20% (10 mL). For each strain, the higher the inoculum size, the higher the degradation rate of malathion. At an inoculum size of 10% (5 mL), the degradation rate of malathion by *Shewanella onychomycosis* MR-1 was 53.00%. Although the degradation rate was positively correlated with the inoculum size, when the inoculum size exceeded 10%, the effect of excessive inoculum size on improving the removal of malathion was limited. This may be because an excessively high initial inoculum size would greatly increase the number of bacteria in the culture medium, while the supply of nutrients would be relatively insufficient, thus leading to intraspecific competition. Therefore, in subsequent studies of this experiment, an inoculum size of 10% (5 mL) was used.

[0102] 2. Effect of pH on the degradation of malathion

[0103] (1) Test scheme

[0104] Using sterile inorganic salt culture medium as the background electrolyte, 10% (5 mL) of OD was added to a 50 mL culture system. 600 =1 Shewanella onychomycosis MR-1 bacterial suspension, malathion concentration set at 10 mg / L, pH adjusted to 4, 5, 6, 7 and 8 using sodium hydroxide and hydrochloric acid, nitrogen purging for deoxygenation, butyl rubber stopper sealing, cultured at 35℃ and 160 rpm, samples taken at regular intervals, extraction and determination of malathion concentration.

[0105] (2) Discussion of Results

[0106] The degradation capacity of malathion by *Oneda Shewanella* MR-1 under different pH conditions is shown in the figure. Figure 7 pH value has a significant impact on the degradation ability of bacterial strains, especially at pH < 5, where strain activity is inhibited and degradation ability is weak; at pH 7, the strain exhibits vigorous growth and metabolism, achieving its maximum degradation capacity. In a slightly alkaline environment, malathion undergoes hydrolysis, with a degradation rate slightly lower than at pH 7. At pH 7, the highest degradation rate of *Onedashewanella MR-1* was 52.84%. These results indicate that pH plays a crucial role in the degradation of malathion by *Onedashewanella MR-1*.

[0107] 3. Effect of temperature on the degradation of malathion

[0108] (1) Test scheme

[0109] Using sterile inorganic salt culture medium as the background electrolyte, 10% (5 mL) of OD was added to a 50 mL culture system. 600=1 Shewanella onychomycosis MR-1 bacterial suspension, malathion concentration set at 10 mg / L, pH adjusted to 7, nitrogen purging for deoxygenation, butyl rubber stopper sealing, constant temperature shaker speed at 160 rpm, culture temperature at 25℃, 30℃, 35℃ and 40℃, sampling at regular intervals, extraction and determination of malathion concentration.

[0110] (2) Discussion of Results

[0111] The degradation ability of *Onedashewanella MR-1* against malathion under different temperature conditions is shown in the figure. Figure 8 The degradation rate of malathion by *Oneladaswana* MR-1 was optimal at 35℃, reaching 53.50%. Below 35℃, the degradation rate increased from 45.74% to 50.46% with temperature variation; however, at 40℃, the degradation rate decreased to 39.05%. Therefore, the optimal degradation temperature is 35℃. The influence of temperature on the degradation rate of malathion by *Oneladaswana* MR-1 is likely due to the optimal growth temperature for most microorganisms and the optimal reaction temperature for enzymes.

[0112] 4. Effect of Fe / C composite material addition on the degradation of malathion by *Schizophyllum ononida* MR-1

[0113] (1) Test scheme

[0114] This experiment investigated the effect of different amounts of Fe / C composite material on the degradation of malathion by *Shewanella onychomycosis onesda* MR-1. Sterile inorganic salt medium was used as the background electrolyte, and 10% (5 mL) OD200 was added to 50 mL of the culture system. 600 =1 Shewanella onychomycosis bacterial suspension, malathion concentration set at 10 mg / L, Fe / C composite material added to the system at amounts of 0.1, 0.2, 0.3, and 0.4 g / L respectively, pH adjusted to 7, nitrogen purging for deoxygenation, butyl rubber stopper sealing, cultured at 35℃ and 160 rpm, samples taken after 3 days, extracted and malathion concentration determined.

[0115] (2) Discussion of Results

[0116] The degradation ability of *Schizothorax on malathion* by *Oneda Shewanella* under different Fe / C composite material addition levels is shown in the figure. Figure 9 The figure shows that when the concentrations of the Fe / C composite material were 0.1, 0.2, 0.3, and 0.4 g / L, the degradation rates of malathion by *Heliotropium onychomycium* were 90.52%, 98.02%, 95.21%, and 92.83%, respectively. The Fe / C composite material showed the best degradation effect on malathion when the concentration was 0.2 g / L.

[0117] 5. Analysis of degradation products

[0118] The liquid chromatography-mass spectrometry (LC-MS) was performed using an Agilent 1290UPLC and an Agilent Q / TOF 6550 system.

[0119] Instrument conditions: Liquid chromatography (Agilent 1290UPLC); Mass spectrometry (Agilent Q / TOF 6550); Mobile phase A: 0.1% formic acid aqueous solution; Mobile phase B: acetonitrile solution; Mobile phase ratios are shown in Table 1.

[0120] Table 1. Proportion of mobile phase

[0121]

[0122] Flow rate: 0.3 mL / min; Injection volume: 5 μL; Column: Waters BEH C182.1*100 mm 1.7 μm; Mass spectrometry scan range: Stage 1 30-800 m / z; Sheath gas temp: 350℃; Sheath gas flow: 12 L / min; ESI + Mode: Voltage 4000V; ESI - Mode: Voltage 3200V. To avoid interference from inorganic salt ions, solid-phase extraction was performed on the sample before analysis: the Waters C18 solid-phase extraction column was activated with 5 mL of methanol and 5 mL of deionized water. After sample loading, impurities were washed away with 5 mL of deionized water, followed by elution with 5 mL of methanol. The collected liquid was dried by nitrogen blowing and then reconstituted with 0.2 mL of methanol before injection.

[0123] Results: Seven degradation products were mainly detected, with molecular formulas C2H7O2PS2, C2H7O3PS, CH5O3PS, H3O3PS, and C8H2PS. 14 O4, C6H 10 O4 and C4H6O4 suggest that the degradation of malathion is caused by the breaking of S-C bonds.

[0124] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A material for degrading the pesticide malathion, characterized in that, Includes Fe / C composite material and Oneida Shewanella bacteria loaded within the pores of the Fe / C composite material; The preparation method of the Fe / C composite material includes the following steps: Bamboo and ammonia water are mixed and boiled. The boiled bamboo is then washed and dried to obtain the first dry bamboo. The first dried bamboo was mixed with ferric nitrate solution and soaked. The soaked bamboo was then dried to obtain the second dried bamboo. The second dried bamboo was roasted and cooled to obtain the Fe / C composite material.

2. The material for degrading the pesticide malathion according to claim 1, characterized in that, The ferric nitrate solution uses a mixture of ethanol and water as a solvent; the volume ratio of ethanol to water in the mixture is 1:

1.

3. The material for degrading the pesticide malathion according to claim 1, characterized in that, The roasting temperature is 600℃; the roasting time is 3 hours.

4. The material for degrading the pesticide malathion according to claim 1, characterized in that, The materials used to degrade the pesticide malathion also include cultures for cultivating Oneda Shewanella.

5. The application of the material for degrading the pesticide malathion according to any one of claims 1 to 4 in the degradation of the pesticide malathion.

6. A method for degrading the pesticide malathion, characterized in that, The following steps are involved: The material for degrading the pesticide malathion, as described in any one of claims 1 to 4, is applied to the sample containing malathion to be degraded, thereby carrying out degradation.

7. The method according to claim 6, characterized in that, The degradation occurs at a pH of 6 to 8 and at a temperature of 30 to 35°C.

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