Biological ferromanganese mineral composite material as well as preparation method and application thereof

Abstract

The invention belongs to the technical crossing field of microorganisms and environmental engineering, and particularly relates to a biological ferromanganese mineral composite material as well as a preparation method and application thereof. According to the present invention, manganese oxidizing bacteria are adopted as an inducer to induce an iron-containing compound and a manganese-containing compound to perform a biological mineralization reaction so as to obtain the manganese oxidizing bacteria, and the manganese oxidizing bacteria are Princisteria sp. Z-MLHA-1, and are preserved in China Center for Type Culture Collection (CCTCC) on December 18, 2024, and the preservation number is CCTCC NO: M 20242853; according to the method, the iron-containing compound and the manganese-containing compound are induced by manganese oxidizing bacteria to generate biological mineralization reaction, a bacterium-mineral complex form is formed, a large number of active sites are provided for heavy metal adsorption, the iron-manganese mineral composite material can convert iron and manganese ions into a low-solubility mineral form through the metabolic activity of microorganisms, and the iron-manganese mineral composite material can be used for adsorbing heavy metals. Therefore, the removal effect on heavy metals such as arsenic and cadmium is enhanced.

Description

Technical Field

[0001] The invention belongs to the intersecting field of microorganism and environmental engineering technology, 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 unreasonable discharge of industrial wastewater has become a global environmental problem that needs to be solved 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, seriously threatening human health and ecological environmental safety. Among them, arsenic is one of the elements widely present in nature, with strong toxicity, and has a significant impact on ecosystems and human health. Cadmium, as another important heavy metal pollutant, is widely present in wastewater, waste gas and solid waste, and has strong biological toxicity, especially to the kidneys and skeletal system. Under combined pollution, the synergistic toxic effects of arsenic and cadmium will aggravate the potential ecological risks. For example, cadmium can promote the solubility of arsenic, enhance its biological effectiveness, and further threaten human health and ecosystem stability. Therefore, the simultaneous and effective purification of arsenic and cadmium composite polluted wastewater is particularly important.

[0003] At present, the mainstream technologies for treating arsenic-cadmium composite polluted wastewater based on environmental functional materials include adsorption, chemical precipitation and biological methods. However, adsorption and chemical precipitation treatment technologies have significant defects such as low efficiency, high cost and high risk of secondary pollution, which are difficult to meet actual needs; among them, the microbial method mainly purifies heavy metal polluted wastewater through the life activities and metabolites of functional bacterial agents such as Bacillus, Bacillus polymyxa and Pseudomonas brucellae, but the growth and metabolic activities of microorganisms are sensitive to environmental conditions, and the complex heavy metal polluted wastewater environment has a great influence on the activity of microorganisms and the stability of purification effect. 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 thereof. Manganese oxidizing bacteria are used as inducers to induce biomineralization reactions of 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 microbially mediated biological-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 a variety of 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 iron-containing compounds and manganese-containing compounds, wherein the manganese-oxidizing bacteria is Priestia sp. Z-MLHA-1 ( Priestia sp . Z-MLHA-1), which was deposited at the China Center for Type Culture Collection on December 18, 2024, with the deposit number CCTCC NO: M 20242853.

[0007] It should be noted that in the method for preparing the biological iron-manganese mineral composite material provided by the present invention, manganese-oxidizing bacteria are used 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 a morphology of a bacteria-mineral complex and contains a porous structure. Its specific surface area is as high as 270.3 m 2 / g, and the pore volume is 0.38 cm 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 abundant -OH groups. The biological iron-manganese mineral composite material can convert iron ions and manganese ions into mineral forms with low solubility through the metabolic activities of microorganisms, thereby enhancing its removal effect on heavy metals such as arsenic and cadmium; and the microorganism-mediated bio-metal oxide composite material has strong stability, forming a multi-functional synergistic system, breaking through the treatment bottleneck of single materials for composite 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 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 various heavy metal pollutants, providing a new, efficient, environmentally friendly and economical solution for the purification of composite heavy metal polluted wastewater and water pollution treatment, and having strong adaptability and broad application prospects.

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

[0009] Biological material preservation information: The manganese-oxidizing bacteria are Priestia sp. Z-MLHA-1 (Priestia sp . Z-MLHA-1) was deposited at the China Center for Type Culture Collection (abbreviation: CCTCC M) on December 18, 2024. The deposit number is CCTCC NO: M 20242853, and the deposit address is Bayi Road, Wuchang District, Wuhan City, Hubei Province.

[0010] Furthermore, the preparation method of the bio-ferromanganese mineral composite material includes the following steps: Inoculate the manganese-oxidizing bacterial seed liquid into one-fifth of the NB medium system, add soluble divalent iron compounds and soluble divalent manganese compounds to the one-fifth NB medium system, and perform aerobic shaking culture. Under the induction of manganese-oxidizing bacteria, Fe 2+ and Mn 2+ undergo a biomineralization reaction to obtain a bio-ferromanganese mineral composite material.

[0011] The preparation method provided by the present invention improves the ecological compatibility of the bio-ferromanganese mineral composite material by adding microorganisms, reduces the use of chemical agents, and enhances the resource utilization degree of microbial biomass. It does not require complex chemical synthesis steps, and the microbial culture and mineralization processes are relatively simple, with low costs, and are suitable for large-scale applications.

[0012] In a specific embodiment, after the reaction is completed, a reaction solution is obtained. The supernatant is removed from the reaction solution by solid-liquid separation. Centrifugal separation is used for solid-liquid separation. The conditions for centrifugal separation are: the rotation speed is 8000 rpm, the time is 10 min. After the precipitate is washed repeatedly 3 times with sterile deionized water, a vacuum freeze dryer is used to continuously freeze-dry at a temperature of -55°C to -40°C for 48 h to obtain a bio-ferromanganese mineral composite material.

[0013] In a specific embodiment, the inoculation amount of the manganese-oxidizing bacterial seed liquid is 1% - 5% of the volume of the one-fifth NB medium system.

[0014] In a specific embodiment, in the one-fifth NB medium system, the concentration of Fe 2+ is 0.5 mmol / L - 1.5 mmol / L. In a preferred example, the concentration of Fe 2+ in the one-fifth NB medium system is 1 mmol / L.

[0015] In a specific embodiment, in the one-fifth NB medium system, the concentration of Mn 2+ is 0.2 mmol / L - 2 mmol / L. In a preferred example, the concentration of Mn 2+ in the one-fifth NB medium system is 0.5 mmol / L.

[0016] In a specific embodiment, the soluble divalent iron compound is FeSO 4 ·7H 2 O, and the soluble divalent manganese compound is MnCl 2 ·4H 2 O.

[0017] In a specific embodiment, the temperature of aerobic shaking culture is 25 °C to 35 °C, the rotation speed is 120 rpm to 160 rpm, and the culture time is 2 d to 10 d. In a preferred example, the temperature of aerobic shaking culture is 30 °C, the rotation speed is 150 rpm, and the culture time is 7 d.

[0018] The second object of the present invention is to provide a bio-ferromanganese mineral composite material prepared by using the above preparation method. The bio-ferromanganese mineral composite material provided by the present invention has a morphology of a bacteria-mineral complex and contains a porous structure. Its specific surface area is as high as 270.3 m 2 / g, the pore volume is 0.38 cm 3 / g. The Fe and Mn oxide components in the bio-ferromanganese mineral composite material mainly present an amorphous structure, and the surface of the composite material contains abundant -OH groups. The bio-ferromanganese mineral composite material can convert iron and manganese ions into a mineral form with low solubility through the metabolic activities of microorganisms, thereby enhancing its removal effect on heavy metals such as arsenic and cadmium.

[0019] The third object of the present invention is to provide the application of the above bio-ferromanganese mineral composite material in removing heavy metals in water, and the heavy metals are arsenic or / and cadmium. The bio-ferromanganese mineral composite material provided by the present invention can simultaneously remove various heavy metal pollutants such as arsenic and cadmium in water during the same treatment process, has a heterogeneous multi-layer adsorption effect, and in the purification of arsenic-cadmium composite polluted wastewater by the bio-ferromanganese mineral composite material, arsenic and cadmium synergistically promote each other, and has strong adaptability and broad application prospects.

[0020] The present invention has the following beneficial effects compared with the prior art: (1) The preparation method of the bio-ferromanganese mineral composite material provided by the present invention uses manganese-oxidizing bacteria as an inducer to carry out a biomineralization reaction on Fe 2+ and Mn 2+ to obtain. The bio-ferromanganese mineral composite material has a morphology of a bacteria-mineral complex and contains a porous structure. Its specific surface area is as high as 270.3 m 2 / g, the pore volume is 0.38 cm 3 / g, the Fe and Mn oxide components in the bio-ferromanganese mineral composite mainly exhibit an amorphous structure, and the surface of the composite contains abundant -OH groups. The bio-ferromanganese mineral composite can convert iron ions and manganese ions into mineral forms with low solubility through the metabolic activities of microorganisms, thereby enhancing its removal effect on heavy metals such as arsenic and cadmium. Moreover, the bio-metal oxide composite mediated by microorganisms has strong stability, forming a multi-functional synergistic system, breaking through the treatment bottleneck of single materials for composite 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 bio-mineralization process, reducing the risk of environmental pollution through the synergistic effect of microbial mineralization and ferromanganese minerals. The manganese-oxidizing bacteria used in the present invention were isolated from the high-manganese soil environment of a metal mining area in Hanzhong, Shaanxi, and the manganese-oxidizing bacteria are Priestia sp. Z-MLHA-1 ( Priestia sp . Z-MLHA-1), and this manganese-oxidizing bacteria can induce bio-mineralization reactions on iron-containing compounds and manganese-containing compounds to form the morphology of a bacterium-mineral complex, providing a large number of active sites for the adsorption of heavy metals.

[0021] (2) The present invention improves the ecological compatibility of the bio-ferromanganese mineral composite through the addition of microorganisms, can efficiently and synchronously remove various heavy metal pollutants, provides a new, efficient, environmentally friendly and economical solution for the purification of composite heavy metal polluted wastewater and water pollution treatment, has strong adaptability and broad application prospects, reduces the use of chemical agents, and strengthens the utilization degree of microbial biomass resources. It does not require complex chemical synthesis steps, and the microbial culture and mineralization processes are relatively simple with low costs, being suitable for large-scale applications. Description of the Drawings

[0022] Figure 1 It is a physical picture of the bio-ferromanganese mineral composite prepared in Example 1 of the present invention.

[0023] Figure 2 It is a microscopic structure picture of the bio-ferromanganese mineral composite prepared in Example 1 of the present invention.

[0024] Figure 3 It is an X-ray diffraction spectrum picture of the bio-ferromanganese mineral composite prepared in Example 1 of the present invention.

[0025] Figure 4 It is a Fourier transform infrared spectroscopy spectrum picture of the bio-ferromanganese mineral composite prepared in Example 1 of the present invention.

[0026] Figure 5 It is an adsorption performance picture of arsenic and cadmium by the bio-ferromanganese cadmium mineral composite prepared in Example 1 of the present invention. Figure 5In Figure (a), it shows the adsorption performance of As, and in Figure (b), it shows the adsorption performance of Cd.

[0027] Figure 6 This is the adsorption isotherm diagram of arsenic and cadmium by the bio - iron - manganese mineral composite material prepared in Example 1 of the present invention. Figure 6 In Figure (a), it is the adsorption isotherm diagram of As(V), and in Figure (b), it is the adsorption isotherm diagram of Cd(II).

[0028] Figure 7 This is the diagram showing the influence of ionic strength on the adsorption performance of arsenic and cadmium by the bio - iron - manganese mineral composite material prepared in Example 1 of the present invention. Figure 7 In Figure (a), it is the diagram showing the influence on the performance of As(V), and in Figure (b), it is the diagram showing the influence on the performance of Cd(II).

[0029] Figure 8 This is the diagram of the microstructure and X - ray energy - dispersive spectrum of the bio - iron - manganese mineral composite material prepared in Example 1 of the present invention for the adsorption of arsenic and cadmium. Figure 8 In Figure (a), it is the scanning electron microscope image, in Figure (b), it is the X - ray energy - dispersive spectrum diagram, in Figure (c), it is the distribution diagram of Fe element, in Figure (d), it is the distribution diagram of Mn element, in Figure (e), it is the distribution diagram of As element, and in Figure (f), it is the distribution diagram of Cd element. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0031] 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 protection scope of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the following embodiments of the present invention can be obtained through market purchase or prepared by existing methods.

[0032] Screening and identification of manganese - oxidizing bacteria (0) Culture medium Preparation of Mn(II) - containing selective NB medium: 5 g / L NaCl, 3 g / L beef extract powder, 10 g / L peptone, adjust the pH to 7.20. The Mn(II) - containing selective NB medium contains 15 mmol HEPES buffer and 0.5 mmol Mn(II). Mn(II) is in the form of MnCl 2 ·4H 2It is prepared by adding it in the form of O and autoclaving at 121 °C for 30 min.

[0033] (1) Screening, isolation and identification Take 1.0 g of high-manganese soil sample from the metal mining area in Hanzhong, Shaanxi. Mix it with 10 mL of sterile water in a 20 mL sterile serum bottle. After manual shaking, draw 5 mL of suspension from the mixed culture and add it to a 250 mL conical flask containing 150 mL of Mn(II)-selective NB medium. Place it in a constant temperature shaking incubator and continuously culture it at 120 r / min, 30 °C, and aerobic conditions for 5 days. Then, transfer the culture to fresh Mn(II)-selective NB medium again, and repeat the acclimation culture at least 3 times to enrich manganese-oxidizing bacteria.

[0034] The dilution coating method is combined with the LBB colorimetric method. Among them, the full English name of LBB is Leukoberbelin blue I for bacterial screening, purification and Mn(II) oxidation activity identification. Perform 16S rRNA sequencing on the dominant strains, use MEGA 7.0 software to construct a microbial phylogenetic tree, and determine the species classification of the strains through BLAST alignment (similarity > 99%). The full English name of BLAS is Tbasic local alignment search tool.

[0035] After identification, this strain is Priestia sp. Priestia It is named Z-MLHA-1 and is deposited in the China Center for Type Culture Collection with the deposit number CCTCC NO: M 20242853.

[0036] Example 1 A method for preparing a bio-ferromanganese mineral composite material, comprising the following steps: Inoculate the manganese-oxidizing bacterium Z-MLHA-1 into one-fifth of the NB medium system. The inoculation amount of the manganese-oxidizing bacterium Z-MLHA-1 is 5% of the volume of the NB medium system. Then, add FeSO 4 ·7H 2 O and MnCl 2 ·4H 2 O. In the one-fifth NB medium system, the concentration of Fe 2+ is 0.5 mmol / L, and the concentration of Mn 2+The concentration is 1 mmol / L. It is aerobically shaken and cultured at 30 °C and 120 rpm for 7 days. Under the induction of manganese-oxidizing bacteria, a biomineralization reaction occurs between divalent iron compounds and divalent manganese compounds. After the reaction ends, a reaction solution is obtained. The supernatant is removed from the reaction solution by solid-liquid separation. Centrifugal separation is used for solid-liquid separation. The conditions for centrifugal separation are: the rotation speed is 8000 rpm and the time is 10 min. After the precipitate is washed repeatedly with sterile deionized water 3 times, a vacuum freeze dryer is used to continuously freeze-dry at -40 °C for 48 h to obtain a bio-ferromanganese mineral composite material. The physical picture of the prepared bio-ferromanganese mineral composite material is as shown in Figure 1 shown.

[0037] Example 2 A preparation method of a bio-ferromanganese mineral composite material includes the following steps: Inoculate manganese-oxidizing bacteria Z-MLHA-1 into an NB culture medium system with a mass concentration of one-fifth. The inoculation amount of manganese-oxidizing bacteria Z-MLHA-1 is 1% of the volume of the NB culture medium system. Then, add FeSO 4 ·7H 2 O and MnCl 2 ·4H 2 O to the one-fifth NB culture medium system. The concentration of Fe 2+ in the one-fifth NB culture medium system is 1 mmol / L, and the concentration of Mn 2+ is 0.2 mmol / L. It is aerobically shaken and cultured at 30 °C and 120 rpm for 7 days. Under the induction of manganese-oxidizing bacteria, a biomineralization reaction occurs between divalent iron compounds and divalent manganese compounds. After the reaction ends, a reaction solution is obtained. The supernatant is removed from the reaction solution by solid-liquid separation. Centrifugal separation is used for solid-liquid separation. The conditions for centrifugal separation are: the rotation speed is 8000 rpm and the time is 10 min. After the precipitate is washed repeatedly with sterile deionized water 3 times, a vacuum freeze dryer is used to continuously freeze-dry at -40 °C for 48 h to obtain a bio-ferromanganese mineral composite material.

[0038] Example 3 A preparation method of a bio-ferromanganese mineral composite material includes the following steps: Inoculate manganese-oxidizing bacteria Z-MLHA-1 into a one-fifth NB culture medium system. The inoculation amount of manganese-oxidizing bacteria Z-MLHA-1 is 3% of the volume of the NB culture medium system. Then, add FeSO 4 ·7H 2 O and MnCl 2 ·4H 2 O to the one-fifth NB culture medium system. The concentration of Fe 2+ in the one-fifth NB culture medium system is 1.5 mmol / L, and Mn2+ The concentration was 2 mmol / L. It was aerobically shaken and cultured at 30 °C and 120 rpm for 7 days. Under the induction of manganese-oxidizing bacteria, a biomineralization reaction occurred between divalent iron compounds and divalent manganese compounds. After the reaction ended, a reaction solution was obtained. The supernatant was removed from the reaction solution by solid-liquid separation. Centrifugal separation was used for solid-liquid separation. The conditions for centrifugal separation were: the rotation speed was 8000 rpm and the time was 10 min. After the precipitate was washed repeatedly with sterile deionized water 3 times, a vacuum freeze dryer was used to continuously freeze-dry at -40 °C for 48 h to obtain a bioiron-manganese mineral composite material.

[0039] Since the bioiron-manganese mineral composite materials prepared in Examples 1 to 3 have basically similar structures and basically the same properties, taking Example 1 as an example, the morphology and structure of the bioiron-manganese mineral composite material prepared in Example 1 were studied, and the results are shown below.

[0040] Figure 2 This is the microscopic structure diagram of the bioiron-manganese mineral composite material prepared in Example 1 of the present invention. As Figure 2 shown, the bioiron-manganese mineral composite material induced by strain Z-MLHA-1 is in the form of a bacterium-mineral complex, with a rough surface and a porous structure. Its specific surface area is as high as 270.3 m² / g, the pore volume is 0.38 cm³ / g, and the average pore diameter is 6.35 nm.

[0041] Furthermore, through X-ray diffraction and Fourier transform infrared spectroscopy analysis, Figure 3 This is the X-ray diffraction pattern of the bioiron-manganese mineral composite material prepared in Example 1 of the present invention, Figure 4 This is the Fourier transform infrared spectroscopy pattern of the bioiron-manganese mineral composite material prepared in Example 1 of the present invention. As Figures 3 - 4 shown, the Fe and Mn oxide components in the bioiron-manganese mineral composite material mainly exhibit an amorphous structure, and the surface of the composite material contains abundant -OH groups. The above composite material structure characteristics can provide a large number of active sites for the adsorption of heavy metals and have strong adsorption potential.

[0042] Application Example 1 The present invention provides the application of the bioiron-manganese mineral composite material prepared in Example 1 above in the purification treatment of arsenic or / and cadmium composite polluted wastewater, which specifically includes the following steps: (1) Adsorption kinetics study.

[0043] The simulated single arsenic-containing composite polluted wastewater and single cadmium-containing composite polluted wastewater were prepared by adding As(V) and Cd(II) respectively. Among them, As(V) was in the form of Na 3 AsO 4 ·12H 2in the form of O, Cd(II) was added as CdCl with a concentration of 1000 μg / L 2 ·5H 2 O; 0.2 g / L of the bio-ferromanganese mineral composite was added to the simulated wastewater, and it was oscillated and cultured in a constant-temperature oscillator at 25 °C with a rotation speed of 120 r / min for 4 d. Samples were taken regularly to measure the concentration changes of As and Cd in the solution. The pseudo-first-order and pseudo-second-order kinetic models were used to fit and analyze the adsorption kinetics of As and Cd by the composite material.

[0044] (2) Isothermal adsorption study.

[0045] 0.2 g / L of the ferromanganese mineral was added to a series of composite simulated wastewaters containing arsenic and cadmium with different initial concentrations, where the concentration of As(V) was 0 mg / L - 20 mg / L, the concentration range of Cd(II) was 0 mg / L - 10 mg / L, and the initial pH value was 7.0. It was placed in a constant-temperature oscillator and oscillated and cultured at a rotation speed of 120 r / min and a temperature of 30 °C for 4 d, and then the concentrations of As and Cd in the solution were measured. The Langmuir and Freundlich models were used to fit and analyze the isothermal adsorption data of As and Cd on the composite material.

[0046] (3) Influence of ionic strength on the adsorption of arsenic and cadmium by the composite material.

[0047] The ionic strength in the simulated wastewater containing As(V) and Cd(II) was adjusted by different concentrations such as 0.001 mol / L, 0.01 mol / L, 0.1 mol / L, and 1 mol / L of NaNO 3 respectively, and the influence of ionic strength on the adsorption of arsenic and cadmium by the bio-ferromanganese mineral composite material was investigated. In different concentration systems, the initial concentrations of As(V) and Cd(II) were 1 mg / L, the addition amount of the bio-ferromanganese mineral composite material was 0.2 g / L, and the initial pH was 7.0. It was placed in a constant-temperature oscillator and oscillated and cultured at a rotation speed of 120 r / min and a temperature of 25 °C for 4 d, then samples were taken to measure the concentrations of arsenic and cadmium in the solution to evaluate the influence of ionic strength on the adsorption of arsenic and cadmium by the bio-ferromanganese mineral composite material.

[0048] Figure 5 This is the adsorption performance diagram of arsenic and cadmium by the ferromanganese-cadmium mineral composite material prepared in Example 1 of the present invention. Figure 5 In the figure (a), it is the adsorption performance of As, and in the figure (b), it is the adsorption performance of Cd. As Figure 5 shown in the figure (a), during the fixation process of As(V) by the ferromanganese mineral, the concentration of As(V) in the solution rapidly decreased from 1000 μg / L to 300.88 μg / L within the first 46 h and tended to be stable after 48 h. After 96 h, the final fixation efficiency of As(V) by the ferromanganese mineral was 82%. AsFigure 5 As shown in Figure (b) in Figure 5 , during the adsorption process of iron and manganese minerals on Cd(II), within 6 hours, the concentration of Cd(II) decreased sharply from the initial 1000 μg / L to 123.49 μg / L. Subsequently, the concentration of Cd(II) gradually reached a stable state after 36 hours. After 96 hours, the fixation efficiency of iron and manganese minerals on Cd(II) was as high as 91%, showing excellent adsorption performance. In the arsenic and cadmium mixed system, the adsorption efficiencies of iron and manganese minerals on arsenic were 97% and 98% respectively, while the adsorption efficiencies in the single arsenic system and the single cadmium system were 82% and 91% respectively. The adsorption efficiencies in the arsenic and cadmium mixed system were higher than those in the single arsenic system and the single cadmium system, indicating that in the purification of arsenic and cadmium composite polluted wastewater by the bio - iron and manganese mineral composite material, arsenic and cadmium synergistically promote each other.

[0049] The analysis of the fixation kinetic model of the bio - iron and manganese mineral composite material on As and Cd shows that the adsorption kinetics of As can be well fitted by the pseudo - first - order kinetic model (R 1 2 = 0.9135) and the pseudo - second - order kinetic model (R 2 2 = 0.9739); the adsorption behavior of Cd also conforms to the predictions of the pseudo - first - order kinetic model (R 1 2 = 0.9307) and the pseudo - second - order kinetic model (R 2 2 = 0.9865), and the predicted fitting parameters are shown in Table 1.

[0050] Table 1 Pseudo - first - order and pseudo - second - order kinetic model parameters for the adsorption of As(V) / Cd(II) by iron and manganese minerals The results in Table 1 show that the adsorption process of the bio - iron and manganese mineral composite material on As(V) and Cd(II) is a process jointly affected by physical and chemical actions.

[0051] The Langmuir and Freundlich models were used to fit the isothermal adsorption results of As(V) and Cd(II) on iron and manganese minerals, and the fitting parameters of the isothermal adsorption results are shown in Table 2.

[0052] Table 2 Fitting parameters of the isothermal adsorption results of As(V) and Cd(II) on iron and manganese minerals Figure 6 is the isothermal adsorption line graph of the bio - iron and manganese mineral composite material prepared in Example 1 of the present invention for arsenic and cadmium. Figure 6 In Figure (a) is the isothermal adsorption line graph of As(V), and in Figure (b) is the isothermal adsorption line graph of Cd(II). As Figure 6As shown in Table 2, in the range of As(V) concentration from 0 mg / L to 20 mg / L, the R values fitted by the Langmuir and Freundlich models are 0.9582 and 0.9816 respectively. For the range of Cd(II) concentration from 0 mg / L to 10 mg / L, the R values fitted by the Langmuir and Freundlich models are 3 2 0.8209 and 0.9482 respectively. The Freundlich model is more suitable for describing the adsorption process of bio-ferromanganese mineral composites to As(V) and Cd(II), which reveals a characteristic of heterogeneous multilayer adsorption. The above adsorption process occurs not only on the functional group sites on the surface of the adsorbent, but also in the mesoporous structure inside it. 4 2 In addition, by changing the ion concentration in the solution, the influence of ionic strength on the adsorption of As(V) and Cd(II) by ferromanganese minerals was investigated.

[0053] This is the graph showing the influence of ionic strength on the performance of the bio-ferromanganese mineral composite prepared in Example 1 of the present invention for adsorbing arsenic and cadmium. Figure 7 In the figure (a) is the graph showing the influence of performance for As(V), and (b) is the graph showing the influence of performance for Cd(II). As Figure 7 shown, as the concentration of NaNO Figure 7 gradually increases from 0.001 mol / L to 1 mol / L, the removal efficiency of ferromanganese minerals for As(V) has no obvious difference and remains in the range of 80.67% to 81.67%; similarly, when the concentration of NaNO 3 increases within the same range, the removal efficiency of ferromanganese minerals for Cd(II) also remains basically stable, in the range of 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. 3 This is the microstructural and X-ray energy dispersive spectroscopy diagram of the bio-ferromanganese mineral composite prepared in Example 1 of the present invention for adsorbing arsenic and cadmium.

[0054] Figure 8 In the figure (a) is the scanning electron microscopy image, (b) is the X-ray energy dispersive spectroscopy diagram, (c) is the Fe element distribution diagram, (d) is the Mn element distribution diagram, (e) is the As element distribution diagram, and (f) is the Cd element distribution diagram. As Figure 8 shown in Figure 8As shown, the surface of the bio-iron-manganese mineral composite is rough and uneven, presenting a granular or spherical aggregated morphology. These minerals tightly wrap around the surface of the bacteria, forming a tight composite structure. After the bio-iron-manganese mineral composite immobilizes arsenic and cadmium, the elemental distribution map shows that Fe, Mn, As, and Cd are enriched on the surface of the bio-iron-manganese mineral composite, presenting a uniform distribution state. Among them, the contents of Fe element, Mn element, As element, and Cd element in the X-ray energy dispersive spectroscopy diagram are shown in Table 3.

[0055] Table 3 Contents of Fe element, Mn element, As element, and Cd element It should be noted that when the present invention involves a numerical range, it should be understood that any value between the two endpoints of each numerical range and the two endpoints can be selected. Since the adopted step methods are the same as those in the embodiments, in order to prevent repetition, the present invention describes the preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0056] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. A method for preparing a biological iron-manganese mineral composite material, characterized in that: The following steps are involved: The manganese oxidizing bacteria are used as inducers to induce biomineralization reaction of iron-containing compounds and manganese-containing compounds. The manganese oxidizing bacteria are 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 CCTCC NO: M 20242853.

2. The method for preparing the biological iron-manganese mineral composite material according to claim 1, characterized in that: The following steps are involved: The manganese oxidizing bacteria seed solution was inoculated into a one-fifth NB culture medium system, and a soluble divalent iron compound and a soluble divalent manganese compound were added to the one-fifth NB culture medium system, and the culture was aerobically shaken. 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 method for preparing the biological iron-manganese mineral composite material according to claim 2, 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 method for preparing the biological iron-manganese mineral composite material according to claim 2, characterized in that: In the one-fifth NB medium system, the Fe 2+ The concentration is 0.5mmol / L~1.5mmol / L.

5. The method for preparing the biological iron-manganese mineral composite material according to claim 2, characterized in that: In the one-fifth NB culture medium system, the Mn 2+ The concentration is 0.2mmol / L~2mmol / L.

6. The method for preparing the biological iron-manganese mineral composite material according to claim 2, characterized in that: The soluble divalent iron compound is FeSO4·7H2O, and the soluble divalent manganese compound is MnCl2·4H2O.

7. The method for preparing the biological iron-manganese mineral composite material according to claim 2, characterized in that: The temperature of aerobic shaking culture is 25°C to 35°C, the rotation speed is 120rpm to 160rpm, and the culture time is 2d to 10d.

8. A biological iron-manganese mineral composite material, characterized in that: The preparation method is described in any one of claims 1 to 7.

9. Use of the biological iron-manganese mineral composite material according to claim 8 in removing heavy metals from water, characterized in that: The heavy metal is arsenic and / or cadmium.

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