Bio-iron-manganese mineral composite material and its preparation method and application

Abstract

The present invention belongs to the intersection of microbiology and environmental engineering technology, and specifically relates to a biological iron-manganese mineral composite material, a preparation method, and an application thereof. The invention is obtained by inducing a biomineralization reaction of iron-containing compounds and manganese-containing compounds using manganese-oxidizing bacteria as an inducer. The manganese-oxidizing bacteria is Priesteria Z-MLHA-1 ( They are sp . Z-MLHA-1), deposited with the China Center for Type Culture Collection on December 18, 2024, with the deposit number CCTCC NO: M 20242853. The present invention uses manganese-oxidizing bacteria to induce biomineralization reactions on iron-containing compounds and manganese-containing compounds, forming a bacteria-mineral complex morphology, which provides a large number of active sites for the adsorption of heavy metals. The iron-manganese mineral composite material can convert iron and manganese ions into low-solubility mineral forms through the metabolic activities of microorganisms, thereby enhancing its removal effect on heavy metals such as arsenic and cadmium.

Description

Technical Field

[0001] The present invention belongs to the interdisciplinary field of microorganisms and environmental engineering technologies, and specifically relates to a biological iron-manganese mineral composite material and a preparation method and application thereof. Background Art

[0002] Arsenic and associated heavy metal pollution induced by mining and irrational discharge of industrial wastewater has become a global environmental problem that needs to be addressed urgently. Especially in polymetallic mining areas with high ecological risks, typical heavy metal pollutants such as arsenic and cadmium often coexist in mine production wastewater, posing a serious threat to human health and ecological and environmental safety. Among them, arsenic is one of the elements that is widely present in nature and is highly toxic, with significant impacts on ecosystems and human health. Cadmium, as another important heavy metal pollutant, is widely present in wastewater, waste gas and solid waste, and is highly biotoxic, especially harmful to the kidneys and skeletal system. Under combined pollution, the synergistic toxic effects of arsenic and cadmium will exacerbate potential ecological risks. For example, cadmium can promote the solubility of arsenic and enhance its bioavailability, further threatening human health and ecosystem stability. Therefore, the simultaneous and effective purification of wastewater contaminated with arsenic and cadmium is particularly important.

[0003] Currently, mainstream technologies for treating arsenic-cadmium combined-contaminated wastewater using environmentally functional materials include adsorption, chemical precipitation, and biological methods. However, adsorption and chemical precipitation treatment technologies have significant drawbacks, such as low efficiency, high cost, and high risk of secondary pollution, making them difficult to meet actual needs. Among them, microbial methods mainly purify heavy metal-contaminated wastewater through the life activities and metabolites of functional bacterial agents such as Bacillus, Paenibacillus polymyxa, and Pseudomonas brucellae. However, the growth and metabolic activities of microorganisms are sensitive to environmental conditions, and the complex heavy metal-contaminated wastewater environment has a significant impact on microbial activity and the stability of purification effects. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a biological iron-manganese mineral composite material and a preparation method and application. Manganese-oxidizing bacteria are used as inducers to induce biomineralization reactions on iron-containing compounds and manganese-containing compounds to obtain a biological iron-manganese mineral composite material. The biological iron-manganese mineral composite material has the form of a bacteria-mineral complex and contains a porous structure. It can convert iron and manganese ions into low-solubility mineral forms through the metabolic activities of microorganisms, thereby enhancing its removal effect on heavy metals such as arsenic and cadmium; and the microbial-mediated bio-metal oxide composite material has strong stability, forming a multifunctional synergistic system. Through the synergistic effect of microbial mineralization and iron-manganese minerals, the present invention can efficiently and synchronously remove multiple heavy metal pollutants.

[0005] The present invention solves the above technical problems through the following technical solutions.

[0006] The first object of the present invention is to provide a method for preparing a biological iron-manganese mineral composite material, comprising the following steps: using manganese oxidizing bacteria as an inducer to induce a biomineralization reaction on an iron-containing compound and a manganese-containing compound, wherein the manganese oxidizing bacteria is Priesteria Z-MLHA-1 ( Priestia sp . Z-MLHA-1), was deposited in the China Center for Type Culture Collection on December 18, 2024, with the deposit number being CCTCC NO: M 20242853.

[0007] It should be noted that the method for preparing the biological iron-manganese mineral composite material provided by the present invention uses manganese-oxidizing bacteria as an inducer to induce a biomineralization reaction on iron-containing compounds and manganese-containing compounds. The prepared biological iron-manganese mineral composite material has the form of a bacteria-mineral complex and contains a porous structure. Its specific surface area is as high as 270.3m 2 / g, pore volume is 0.38cm 3 / g, the Fe and Mn oxide components in the bio-iron-manganese mineral composite material mainly present an amorphous structure, and the surface of the composite material contains abundant −OH groups. The bio-iron-manganese mineral composite material can convert iron ions and manganese ions into low-solubility mineral forms through the metabolic activity of microorganisms, thereby enhancing its removal effect on heavy metals such as arsenic and cadmium; and the microbially mediated bio-metal oxide composite material has strong stability, forming a multifunctional synergistic system, breaking through the bottleneck of single material treatment of complex pollution. The present invention fully utilizes biomass resources and avoids the disadvantages of using large amounts of chemical reagents in traditional water treatment processes through the biomineralization process, reducing the risk of environmental pollution. Through the synergistic effect of microbial mineralization and iron-manganese minerals, the present invention can efficiently and synchronously remove multiple heavy metal pollutants, providing a new, efficient, environmentally friendly and economical solution for the purification of complex heavy metal-contaminated wastewater and water pollution control, with strong adaptability and broad application prospects.

[0008] It should be noted that the manganese oxidizing bacteria used in the present invention are Priestia sp., isolated from high-manganese soil in the Hanzhong metal mining area in Shaanxi Province, was cultured in NB medium at 20°C to 30°C and a rotation speed of 120-160 rpm for 2-10 days to obtain a seed solution of the manganese-oxidizing bacteria. The NB medium consists of 5g sodium chloride, 3g beef extract powder, 10g peptone, and 1L distilled water, with a pH of 7.2. This manganese-oxidizing bacteria can induce biomineralization reactions on iron- and manganese-containing compounds, forming a bacteria-mineral complex that provides a large number of active sites for heavy metal adsorption.

[0009] Biomaterial deposit information: The manganese oxidizing bacteria is Priesteria Z-MLHA-1 ( Priestia sp . Z-MLHA-1), was deposited in the China Center for Type Culture Collection (abbreviated as: CCTCC M) on December 18, 2024, with the deposit number being CCTCC NO: M 20242853. The deposit address is Bayi Road, Wuchang District, Wuhan City, Hubei Province.

[0010] Furthermore, the preparation method of the biological iron-manganese mineral composite material comprises the following steps:

[0011] The manganese oxidizing bacteria seed solution was inoculated into one-fifth of the NB culture medium system, and soluble divalent iron compounds and soluble divalent manganese compounds were added to the one-fifth of the NB culture medium system, and aerobic shaking culture was performed. Under the induction of manganese oxidizing bacteria, Fe 2+ and Mn 2+ A biomineralization reaction occurs to obtain a bio-iron-manganese mineral composite material.

[0012] The preparation method provided by the present invention improves the ecological compatibility of the biological iron-manganese mineral composite material by adding microorganisms, reduces the use of chemical agents, and enhances the resource utilization of microbial biomass. It does not require complex chemical synthesis steps, and the microbial culture and mineralization processes are relatively simple, low-cost, and suitable for large-scale application.

[0013] In a specific embodiment, after the reaction is completed, a reaction liquid is obtained, and the supernatant is removed from the reaction liquid by solid-liquid separation. The solid-liquid separation is performed by centrifugation. The conditions for centrifugation are: a speed of 8000 rpm, a time of 10 min, and the precipitate is repeatedly washed three times with sterile deionized water. Then, a vacuum freeze dryer is used to continuously freeze-dry for 48 hours at a temperature of -55°C to -40°C to obtain a biological iron-manganese mineral composite material.

[0014] In a specific embodiment, the inoculation amount of the manganese oxidizing bacteria seed solution is 1% to 5% of the volume of one-fifth of the NB culture medium system.

[0015] In a specific embodiment, in the one-fifth NB culture medium system, the Fe 2+ The concentration is 0.5mmol / L to 1.5mmol / L. In a preferred embodiment, Fe 2+ The concentration in one-fifth NB culture medium is 1 mmol / L.

[0016] In a specific embodiment, in the one-fifth NB culture medium system, the Mn 2+ The concentration is 0.2mmol / L to 2mmol / L. In a preferred embodiment, Mn 2+ The concentration in one-fifth NB culture medium system is 0.5 mmol / L.

[0017] In a specific embodiment, the soluble divalent iron compound is FeSO4·7H2O, and the soluble divalent manganese compound is MnCl2·4H2O.

[0018] In a specific embodiment, the temperature of the aerobic shaking culture is 25°C to 35°C, the rotation speed is 120 rpm to 160 rpm, and the culture time is 2 days to 10 days. In a preferred embodiment, the temperature of the aerobic shaking culture is 30°C, the rotation speed is 150 rpm, and the culture time is 7 days.

[0019] The second object of the present invention is to provide a bio-iron-manganese mineral composite material prepared by the above-mentioned preparation method. The bio-iron-manganese mineral composite material provided by the present invention has the form of a fungus-mineral complex and contains a porous structure. Its specific surface area is as high as 270.3m 2 / g, pore volume is 0.38cm 3 / g, the Fe and Mn oxide components in the bio-iron-manganese mineral composite mainly present an amorphous structure, and the surface of the composite contains abundant −OH groups. The bio-iron-manganese mineral composite can convert iron and manganese ions into low-solubility mineral forms through the metabolic activities of microorganisms, thereby enhancing its removal effect on heavy metals such as arsenic and cadmium.

[0020] A third object of the present invention is to provide the use of the above-mentioned biological iron-manganese mineral composite material for removing heavy metals from water, wherein the heavy metals are arsenic and / or cadmium. The biological iron-manganese mineral composite material provided by the present invention can simultaneously remove multiple heavy metal pollutants such as arsenic and cadmium from water during the same treatment process, exhibiting a heterogeneous multilayer adsorption effect. In addition, when the biological iron-manganese mineral composite material is used to purify wastewater containing arsenic and cadmium composite contamination, arsenic and cadmium promote each other synergistically, thus having strong adaptability and broad application prospects.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The method for preparing the biological iron-manganese mineral composite material provided by the present invention uses manganese oxidizing bacteria as an inducer to induce Fe 2+ and Mn 2+ The bio-iron-manganese mineral composite material is obtained by inducing biomineralization reaction, and has the form of fungus-mineral complex and contains porous structure. Its specific surface area is as high as 270.3m 2 / g, pore volume is 0.38cm 3 / g, the Fe and Mn oxide components in the biological iron-manganese mineral composite material mainly present an amorphous structure, and the surface of the composite material contains rich −OH groups. The biological iron-manganese mineral composite material can convert iron ions and manganese ions into low-solubility mineral forms through the metabolic activities of microorganisms, thereby enhancing its removal effect on heavy metals such as arsenic and cadmium; and the microbial-mediated biological-metal oxide composite material has strong stability, forming a multifunctional synergistic system, breaking through the bottleneck of single material treatment of complex pollution. The present invention makes full use of biomass resources and avoids the disadvantages of using a large amount of chemical reagents in traditional water treatment processes through the biological mineralization process, reducing the risk of environmental pollution, and through the synergistic effect of microbial mineralization and iron-manganese minerals. The manganese oxidizing bacteria used in the present invention are isolated from the high manganese soil environment of the Hanzhong metal mining area in Shaanxi Province. The manganese oxidizing bacteria are Priesteria Z-MLHA-1 ( Priestia sp . Z-MLHA-1), a manganese-oxidizing bacterium, can induce biomineralization reactions on iron-containing compounds and manganese-containing compounds, forming a bacteria-mineral complex morphology, providing a large number of active sites for the adsorption of heavy metals.

[0023] (2) The present invention improves the ecological compatibility of biological iron-manganese mineral composite materials by adding microorganisms, and can efficiently and synchronously remove multiple heavy metal pollutants, providing a new, efficient, environmentally friendly and economical solution for the purification of composite heavy metal polluted wastewater and water pollution control. It has strong adaptability and broad application prospects, reduces the use of chemical agents, and enhances the resource utilization of microbial biomass. It does not require complex chemical synthesis steps, and the microbial culture and mineralization process is relatively simple, low-cost, and suitable for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a physical picture of the biological iron-manganese mineral composite material prepared in Example 1 of the present invention.

[0025] Figure 2 This is a microstructure diagram of the biological iron-manganese mineral composite material prepared in Example 1 of the present invention.

[0026] Figure 3 This is the X-ray diffraction spectrum of the biological iron-manganese mineral composite material prepared in Example 1 of the present invention.

[0027] Figure 4 This is a Fourier transform infrared spectrum of the biological iron-manganese mineral composite material prepared in Example 1 of the present invention.

[0028] Figure 5 This is a graph showing the adsorption performance of the biological iron, manganese and cadmium mineral composite material prepared in Example 1 of the present invention for arsenic and cadmium. Figure 5Figure (a) shows the adsorption performance of As, and Figure (b) shows the adsorption performance of Cd.

[0029] Figure 6 This is the adsorption isotherm diagram of arsenic and cadmium by the biological iron-manganese mineral composite material prepared in Example 1 of the present invention. Figure 6 Figure (a) is the adsorption isotherm of As(V), and Figure (b) is the adsorption isotherm of Cd(II).

[0030] Figure 7 This is a graph showing the effect of ionic strength on the adsorption performance of arsenic and cadmium by the biological iron-manganese mineral composite material prepared in Example 1 of the present invention. Figure 7 Figure (a) is the performance impact diagram of As(V), and Figure (b) is the performance impact diagram of Cd(II).

[0031] Figure 8 The microstructure and X-ray energy dispersion spectrum of the biological iron-manganese mineral composite material prepared in Example 1 of the present invention after adsorption of arsenic and cadmium. Figure 8 Figure (a) is a scanning electron microscope image, Figure (b) is an X-ray energy dispersion spectrum image, Figure (c) is the Fe element distribution map, Figure (d) is the Mn element distribution map, Figure (e) is the As element distribution map, and Figure (f) is the Cd element distribution map. DETAILED DESCRIPTION

[0032] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0034] Screening and identification of manganese-oxidizing bacteria

[0035] (0) Culture medium

[0036] Preparation of Mn(II)-selective NB medium: 5 g / L NaCl, 3 g / L beef extract powder, 10 g / L peptone, adjusted to pH 7.20, 15 mmol HEPES buffer and 0.5 mmol Mn(II) in the form of MnCl2·4H2O. The medium was sterilized by high-pressure steam at 121°C for 30 min.

[0037] (1) Screening, separation and identification

[0038] A 1.0 g sample of high-manganese soil from the Hanzhong metal mining area in Shaanxi Province was mixed with 10 mL of sterile water in a 20 mL sterile serum bottle. After manual shaking, 5 mL of the suspension was aspirated from the mixed culture and added to a 250 mL Erlenmeyer flask containing 150 mL of Mn(II)-selective NB medium. The culture was then incubated in a constant temperature shaker at 120 rpm, 30°C, and aerobic conditions for 5 days. The culture was then transferred to fresh Mn(II)-selective NB medium and the acclimatization culture was repeated at least three times to enrich the manganese-oxidizing bacteria.

[0039] Bacteria were screened, purified, and their Mn(II) oxidation activity was determined using a dilution coating method combined with Leukoberbelin blue I (LBB) chromogenic assay. 16S rRNA sequencing was performed on the dominant strains, and a phylogenetic tree was constructed using MEGA 7.0 software. BLAST (basic local alignment search tool) comparisons (similarity >99%) were used to determine the strain taxonomy.

[0040] The strain was identified as Priesteria spp. Priestia sp.), named Z-MLHA-1, and deposited in China Center for Type Culture Collection with the accession number CCTCC NO: M 20242853.

[0041] Example 1

[0042] A method for preparing a biological iron-manganese mineral composite material comprises the following steps:

[0043] The manganese oxidizing bacteria Z-MLHA-1 was inoculated into one-fifth of the NB culture medium system. The inoculation amount of the manganese oxidizing bacteria Z-MLHA-1 was 5% of the volume of the NB culture medium system. Then FeSO4·7H2O and MnCl2·4H2O were added into the one-fifth of the NB culture medium system. 2+ The concentration of Mn is 0.5mmol / L, 2+The concentration is 1mmol / L, and the culture is aerobic shaken at 30℃ and 120rpm for 7 days. Under the induction of manganese oxidizing bacteria, the divalent iron compound and the divalent manganese compound undergo biomineralization reaction. After the reaction, the reaction liquid is obtained, and the supernatant is removed by solid-liquid separation. The solid-liquid separation is carried out by centrifugation. The conditions of centrifugation are: speed of 8000rpm, time of 10min, and the precipitate is repeatedly washed 3 times with sterile deionized water. Then, a vacuum freeze dryer is used to freeze-dry for 48 hours at a temperature of -40℃ to obtain a biological iron-manganese mineral composite material. The actual picture of the prepared biological iron-manganese mineral composite material is as follows Figure 1 shown.

[0044] Example 2

[0045] A method for preparing a biological iron-manganese mineral composite material comprises the following steps:

[0046] The manganese oxidizing bacteria Z-MLHA-1 was inoculated into a NB culture medium system with a mass concentration of one-fifth, and the inoculation amount of the manganese oxidizing bacteria Z-MLHA-1 was 1% of the volume of the NB culture medium system. Then, FeSO4·7H2O and MnCl2·4H2O were added to the one-fifth NB culture medium system. 2+ The concentration of Mn is 1mmol / L, 2+ The concentration of the product was 0.2 mmol / L, and the product was cultured under aerobic shaking at 30°C and 120 rpm for 7 days. Under the induction of manganese-oxidizing bacteria, the divalent iron compound and the divalent manganese compound underwent biomineralization reaction. After the reaction, a reaction solution was obtained, and the supernatant was removed from the reaction solution by solid-liquid separation. The solid-liquid separation was carried out by centrifugation. The conditions for centrifugal separation were: a speed of 8000 rpm and a time of 10 minutes. The precipitate was repeatedly washed with sterile deionized water for 3 times, and then freeze-dried in a vacuum freeze dryer at a temperature of -40°C for 48 hours to obtain a biological iron-manganese mineral composite material.

[0047] Example 3

[0048] A method for preparing a biological iron-manganese mineral composite material comprises the following steps:

[0049] Manganese oxidizing bacteria Z-MLHA-1 was inoculated into one-fifth of NB culture medium system, and the inoculation amount of manganese oxidizing bacteria Z-MLHA-1 was 3% of the volume of NB culture medium system. Then FeSO4·7H2O and MnCl2·4H2O were added into one-fifth of NB culture medium system. 2+ The concentration of Mn is 1.5mmol / L, 2+The concentration of the product was 2 mmol / L, and the product was cultured under aerobic shaking at 30°C and 120 rpm for 7 days. Under the induction of manganese-oxidizing bacteria, the divalent iron compound and the divalent manganese compound underwent biomineralization reaction. After the reaction, a reaction solution was obtained, and the supernatant was removed from the reaction solution by solid-liquid separation. The solid-liquid separation was carried out by centrifugation. The conditions for centrifugal separation were: a speed of 8000 rpm and a time of 10 minutes. The precipitate was repeatedly washed with sterile deionized water for 3 times, and then freeze-dried in a vacuum freeze dryer at a temperature of -40°C for 48 hours to obtain a biological iron-manganese mineral composite material.

[0050] Since the bio-iron-manganese mineral composite materials prepared in Examples 1 to 3 have basically similar structures and basically the same performance, Example 1 is taken as an example to study the morphology and structure of the bio-iron-manganese mineral composite material prepared in Example 1, and the results are shown below.

[0051] Figure 2 This is a microstructure diagram of the biological iron-manganese mineral composite material prepared in Example 1 of the present invention. Figure 2 As shown in the figure, the biological iron-manganese mineral composite material induced by strain Z-MLHA-1 is in the form of a fungus-mineral complex with a rough surface and a porous structure. Its specific surface area is as high as 270.3m² / g, the pore volume is 0.38cm³ / g, and the average pore diameter is 6.35nm.

[0052] Further analysis by X-ray diffraction and Fourier transform infrared spectroscopy, Figure 3 This is the X-ray diffraction spectrum of the biological iron-manganese mineral composite material prepared in Example 1 of the present invention. Figure 4 This is the Fourier transform infrared spectrum of the biological iron-manganese mineral composite material prepared in Example 1 of the present invention. Figures 3 and 4 As shown in the figure, the Fe and Mn oxide components in the bio-iron-manganese mineral composite material mainly present an amorphous structure, and the surface of the composite material contains abundant −OH groups. The above structural characteristics of the composite material can provide a large number of active sites for the adsorption of heavy metals and have strong adsorption potential.

[0053] Application Example 1

[0054] The present invention provides a biological iron-manganese mineral composite material prepared in Example 1 above for use in the purification of arsenic and / or cadmium composite contaminated wastewater, specifically comprising the following steps:

[0055] (1) Adsorption kinetics study.

[0056] Simulated wastewater containing both arsenic and cadmium was prepared by adding As(V) and Cd(II), respectively. As(V) was added at a concentration of 1000 μg / L in Na₃AsO₄·12H₂O, and Cd(II) was added at a concentration of 1000 μg / L in CdCl₂·5H₂O. A 0.2 g / L bio-iron-manganese mineral composite was added to the simulated wastewater and incubated in an oscillating incubator at 25°C and 120 rpm for 4 days. Samples were taken periodically to measure changes in As and Cd concentrations in the solution. Pseudo-first-order and pseudo-second-order kinetic models were used to fit the arsenic and cadmium adsorption kinetics of the composite.

[0057] (2) Isothermal adsorption study.

[0058] 0.2 g / L of ferromanganese mineral was added to a series of simulated wastewaters containing arsenic and cadmium at varying initial concentrations. The As(V) concentration ranged from 0 mg / L to 20 mg / L, and the Cd(II) concentration ranged from 0 mg / L to 10 mg / L. The initial pH was 7.0. The solution was incubated in a constant-temperature shaker at 120 rpm and 30°C for 4 days. The As and Cd concentrations in the solution were then measured. Langmuir and Freundlich models were used to fit the isothermal adsorption data for As and Cd on the composites.

[0059] (3) Effect of ionic strength on the adsorption of arsenic and cadmium by composite materials.

[0060] The effects of ionic strength on the adsorption of arsenic and cadmium by bio-iron-manganese mineral composites were investigated by adjusting the ionic strength of simulated wastewater containing As(V) and Cd(II) using NaNO3 at different concentrations (0.001 mol / L, 0.01 mol / L, 0.1 mol / L, and 1 mol / L, respectively). Initial As(V) and Cd(II) concentrations were 1 mg / L, the bio-iron-manganese mineral composite was added at 0.2 g / L, and the initial pH was 7.0. After incubation at 120 rpm and 25°C in a constant temperature shaker for 4 days, samples were collected and the arsenic and cadmium concentrations in the solutions were determined to evaluate the effect of ionic strength on the adsorption of arsenic and cadmium by the bio-iron-manganese mineral composites.

[0061] Figure 5 This is a graph showing the adsorption performance of the iron-manganese-cadmium mineral composite material prepared in Example 1 of the present invention for arsenic and cadmium. Figure 5 Figure (a) shows the adsorption performance of As, and Figure (b) shows the adsorption performance of Cd. Figure 5As shown in Figure (a), during the process of As(V) fixation by ferromanganese minerals, the As(V) concentration in the solution dropped rapidly from 1000 μg / L to 300.88 μg / L within the first 46 hours and stabilized after 48 hours. After 96 hours, the final As(V) fixation efficiency of ferromanganese minerals was 82%. Figure 5 As shown in Figure (b), during the adsorption process of Cd(II) by ferromanganese minerals, the concentration of Cd(II) dropped sharply from the initial 1000μg / L to 123.49μg / L within 6 hours. Subsequently, the concentration of Cd(II) gradually reached a stable state after 36 hours. After 96 hours, the fixation efficiency of Cd(II) by ferromanganese minerals reached 91%, showing excellent adsorption performance. In the arsenic and cadmium mixed system, the adsorption efficiency of arsenic by ferromanganese minerals was 97% and 98%, respectively, while the adsorption efficiency of the single arsenic system and the single cadmium system was 82% and 91%, respectively. The adsorption efficiency of the arsenic and cadmium mixture was higher than that of the single arsenic system and the single cadmium system, indicating that arsenic and cadmium promote each other synergistically in the purification of arsenic-cadmium complex wastewater by biological ferromanganese mineral composite materials.

[0062] The analysis of the kinetic model of As and Cd fixation by the bio-iron-manganese mineral composite material showed that the adsorption kinetics of As can be expressed by the pseudo-first-order kinetic model (R1 2 =0.9135) and pseudo-second-order kinetic model (R2 2 =0.9739) is a good fit; the adsorption behavior of Cd also conforms to the pseudo-first-order kinetic model (R1 2 =0.9307) and pseudo-second-order kinetic model (R2 2 =0.9865), and the predicted fitting parameters are shown in Table 1.

[0063] Table 1 Parameters of pseudo-first-order and pseudo-second-order kinetic models for As(V) / Cd(II) adsorption on iron-manganese minerals

[0064]

[0065] The results in Table 1 show that the adsorption process of As(V) and Cd(II) by the bio-iron-manganese mineral composite material is a combined process of physical and chemical effects.

[0066] The Langmuir and Freundlich models were used to fit the isothermal adsorption results of As(V) and Cd(II) on ferromanganese minerals. The fitting parameters of the isothermal adsorption results are shown in Table 2.

[0067] Table 2 Fitting parameters for the isothermal adsorption of As(V) and Cd(II) on ferromanganese minerals

[0068]

[0069] Figure 6 This is the adsorption isotherm diagram of arsenic and cadmium by the biological iron-manganese mineral composite material prepared in Example 1 of the present invention. Figure 6 Figure (a) is the adsorption isotherm of As(V), and Figure (b) is the adsorption isotherm of Cd(II). Figure 6 As shown in Table 2, in the As(V) concentration range of 0 mg / L~20 mg / L, the R3 of the Langmuir and Freundlich models is 2 The R4 values ​​of Langmuir and Freundlich models were 0.9582 and 0.9816, respectively. For the Cd(II) concentration range of 0 mg / L~10 mg / L, the R4 values ​​of Langmuir and Freundlich models were 0.9582 and 0.9816, respectively. 2 The Freundlich model is more suitable for describing the adsorption of As(V) and Cd(II) by biogenic iron-manganese mineral composites, revealing a heterogeneous multilayer adsorption process. This adsorption process occurs not only at functional group sites on the adsorbent surface but also within its internal mesoporous structure.

[0070] In addition, the effect of ionic strength on the adsorption of As(V) and Cd(II) by ferromanganese minerals was investigated by changing the ion concentration in the solution. Figure 7 This is a graph showing the effect of ionic strength on the adsorption performance of arsenic and cadmium by the biological iron-manganese mineral composite material prepared in Example 1 of the present invention. Figure 7 Figure (a) is the performance impact diagram of As(V), and (b) is the performance impact diagram of Cd(II). Figure 7 As shown in the results, as the NaNO3 concentration gradually increased from 0.001 mol / L to 1 mol / L, the removal efficiency of ferromanganese minerals for As(V) remained unchanged, ranging from 80.67% to 81.67%. Similarly, when the NaNO3 concentration increased within the same range, the removal efficiency of ferromanganese minerals for Cd(II) also remained largely stable, ranging from 90.25% to 90.69%. This further supports that the adsorption of As(V) and Cd(II) by ferromanganese minerals is carried out through the inner-sphere complexation mechanism rather than the outer-sphere complexation mechanism.

[0071] Figure 8 The microstructure and X-ray energy dispersion spectrum of the biological iron-manganese mineral composite material prepared in Example 1 of the present invention after adsorption of arsenic and cadmium. Figure 8 Figure (a) is a scanning electron microscope image, Figure (b) is an X-ray energy dispersion spectrum image, Figure (c) is the Fe element distribution map, Figure (d) is the Mn element distribution map, Figure (e) is the As element distribution map, and Figure (f) is the Cd element distribution map. Figure 8As shown, the surface of the bio-iron-manganese mineral composite material is rough and uneven, exhibiting granular or spherical aggregates. These minerals tightly wrap around the bacterial surface, forming a compact complex structure. After arsenic and cadmium were immobilized on the bio-iron-manganese mineral composite material, the elemental distribution diagram shows that Fe, Mn, As, and Cd are enriched and evenly distributed on the surface of the bio-iron-manganese mineral composite material. The contents of Fe, Mn, As, and Cd in the X-ray energy dispersive spectroscopy are shown in Table 3.

[0072] Table 3 Contents of Fe, Mn, As and Cd

[0073]

[0074] It should be noted that when numerical ranges are mentioned in the present invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints may be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes preferred embodiments. Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they understand the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0075] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. Application of a biological iron-manganese mineral composite material in removing arsenic and cadmium from water, characterized in that: The preparation method of the biological iron-manganese mineral composite material comprises the following steps: using manganese oxidizing bacteria as an inducer to induce a biomineralization reaction on an iron-containing compound and a manganese-containing compound, wherein the manganese oxidizing bacteria is Priesteria Z-MLHA-1 ( Priestia sp . Z-MLHA-1), was deposited in the China Center for Type Culture Collection on December 18, 2024, with the deposit number being CCTCC NO: M 20242853.

2. The use of the biological iron-manganese mineral composite material according to claim 1 in removing arsenic and cadmium from water, characterized in that: The preparation method of the biological iron-manganese mineral composite material comprises the following steps: The manganese oxidizing bacteria seed solution was inoculated into one-fifth of the NB culture medium system, and soluble divalent iron compounds and soluble divalent manganese compounds were added to the one-fifth of the NB culture medium system, and aerobic shaking culture was performed. Under the induction of manganese oxidizing bacteria, Fe 2+ and Mn 2+ A biomineralization reaction occurs to obtain a bio-iron-manganese mineral composite material.

3. The use of the biological iron-manganese mineral composite material according to claim 2 in removing arsenic and cadmium from water, characterized in that: The inoculation amount of the manganese oxidizing bacteria seed solution is 1% to 5% of the volume of one-fifth of the NB culture medium system.

4. The use of the biological iron-manganese mineral composite material according to claim 2 in removing arsenic and cadmium from water, characterized in that: In the one-fifth NB culture medium system, the Fe 2+ The concentration is 0.5mmol / L~1.5mmol / L.

5. The use of the biological iron-manganese mineral composite material according to claim 2 in removing arsenic and cadmium from water, characterized in that: In the one-fifth NB culture medium system, the Mn 2+ The concentration is 0.2mmol / L~2mmol / L.

6. The use of the biological iron-manganese mineral composite material according to claim 2 in removing arsenic and cadmium from water, characterized in that: The soluble divalent iron compound is FeSO4·7H2O, and the soluble divalent manganese compound is MnCl2·4H2O.

7. The use of the biological iron-manganese mineral composite material according to claim 2 in removing arsenic and cadmium from water, characterized in that: The temperature of the aerobic shaking culture is 25° C. to 35° C., the rotation speed is 120 rpm to 160 rpm, and the culture time is 2 days to 10 days.

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