Metal ion modified organic pollution biostimulation sustained-release material as well as preparation method and application thereof

Abstract

The invention relates to the field of environment protection, and discloses a metal ion modified organic pollution biostimulation sustained-release material as well as a preparation method and application thereof. The metal ion modified organic pollution biostimulation slow-release material is of a core-shell structure, an inner core contains porous carbon loaded with sulfate, and a shell layer contains metal ion modified porous carbon. Starting from the function development and reutilization of waste biomass, the porous carbon is prepared by taking biomass as a matrix and utilizing molten sulfate etching, the porous carbon loaded with sulfate is obtained, the value of the biochar in the field of slow release function realization is excavated, the porous carbon completely filled with sulfate is taken as a slow release center, and the slow release function of the biochar is realized. The outer layer is coated with metal ion modified porous carbon, so that the free concentration of sulfate radicals in the environment can be further reduced through anion and cation adsorption, complexation, precipitation and other processes after the sulfate radicals on the inner layer are released, and effective slow release control of the core medicament sulfate radicals is realized.

Description

Technical Field

[0001] The present invention relates to the field of environmental protection, and particularly to an organically polluted biostimulatory slow-release material modified with metal ions, and a preparation method and application thereof. Background Art

[0002] The rapid development of industry has given rise to a large number of industrial polluted sites. Among them, the organically polluted sites represented by the polluted sites in the petrochemical industry pose great environmental and health risks. Studying the remediation technologies for organically polluted sites has great and far-reaching practical significance.

[0003] Sulfate-reducing bacteria are anaerobic reducing bacteria that use sulfur oxides such as sulfate, sulfite, and thiosulfate as electron acceptors and are widely present in ecosystems such as soil, seawater, oil and gas fields, and river bottom sludge. In organically polluted environments such as petroleum hydrocarbons and benzene series, sulfate-reducing bacteria can carry out life activities with organic pollutants as carbon sources and sulfate as electron acceptors. During their life cycle, through the dissimilatory action of sulfate-reducing bacteria, sulfate is reduced to S 2- , and part of the carbon source is converted into CO3 2- S 2- and CO3 2- can interact with metal ions to form insoluble precipitates, and through the life activities of sulfate-reducing bacteria, pollutant conversion and removal can be comprehensively achieved. In the existing technical research, the research on sulfate-reducing bacteria is mostly limited to the spontaneous pollutant degradation effect of sulfate-reducing bacteria, and there is less research on stimulating the pollutant degradation effect of sulfate-reducing bacteria with long-term sulfate stimulation. Therefore, relying on sulfate-reducing bacteria in nature to provide an efficient sulfate slow-release agent system to continuously stimulate the life activities of sulfate-reducing bacteria to utilize organic carbon in the environment for a long time is of great significance for achieving pollutant removal and stabilization.

[0004] Traditional slow-release agent types mainly include coating type, polymer matrix type, adsorption type, etc. Among them, the coating technology plays a hindering role in the process of agent diffusion and release, prolonging the agent effect period. Due to its simple implementation and strong operability, it is widely used. Common coating materials are mainly divided into two categories: organic and inorganic. Common inorganic coatings mainly include sulfur, calcium magnesium phosphate fertilizer, insoluble phosphates, etc., and organic coatings are mostly chitosan, sodium alginate, starch, cellulose, etc. Inorganic coatings are brittle and have poor toughness, and organic coatings mostly come from natural biomass and are mostly microbial nutrient organic matters. During their reuse in soil, they are easily preferentially utilized by microorganisms as metabolic substrates, greatly weakening their coating functions and thus affecting the agent slow-release effect.

[0005] Based on the life activities of sulfate-reducing bacteria, a long-acting sulfate slow-release material with a biomass carbon matrix is developed. It will be added to the polluted site as an in-situ remediation agent to continuously stimulate the life activities of sulfate-reducing bacteria, gradually degrade and stabilize the pollutants in the polluted site, and has great research value and practical significance for site remediation and treatment. Summary of the Invention

[0006] The purpose of the present invention is to overcome the problems existing in the prior art, such as the easy decomposition of the slow-release coating, which affects the slow-release performance. The present invention provides a metal-ion modified organic pollution biostimulation slow-release material, its preparation method and application. The metal-ion modified organic pollution biostimulation slow-release material can provide sulfate for the life activities of sulfate-reducing bacteria for a long time by slowly releasing sulfate, stimulate the metabolic activities of sulfate-reducing bacteria in a certain polluted environment, and achieve pollutant degradation and heavy metal stabilization to a certain extent.

[0007] To achieve the above purpose, on the one hand, the present invention provides a metal-ion modified organic pollution biostimulation slow-release material. The metal-ion modified organic pollution biostimulation slow-release material has a core-shell structure, wherein the inner core contains porous carbon loaded with sulfate, and the shell layer contains metal-ion modified porous carbon.

[0008] Preferably, among the porous carbon loaded with sulfate, the sulfate is selected from two or more of magnesium sulfate, calcium sulfate, potassium sulfate, sodium sulfate, iron sulfate and lithium sulfate.

[0009] Preferably, the metal ions are selected from one or more of calcium ions, magnesium ions and iron ions.

[0010] Preferably, in the porous carbon loaded with sulfate, the pore diameter of the porous carbon is 1-70 nm, preferably 1-40 nm.

[0011] Preferably, the raw materials for preparing the porous carbon loaded with sulfate contain biomass.

[0012] Preferably, the pore diameter of the metal-ion modified porous carbon is 1-60 nm, preferably 1-20 nm.

[0013] Preferably, the raw materials for preparing the metal-ion modified porous carbon contain biomass.

[0014] Preferably, the diameter of the metal-ion modified organic pollution biostimulation slow-release material is 1-2.5 mm, preferably 1.25-2 mm.

[0015] Preferably, the diameter of the inner core is 0.5-1.25 mm, preferably 0.6-0.85 mm.

[0016] Preferably, the thickness of the shell layer is 0.35 - 0.65 mm, preferably 0.4 - 0.55 mm.

[0017] In the second aspect of the present invention, a preparation method of the above-mentioned metal ion-modified organic pollution biostimulation slow-release material is provided. The preparation method includes the following steps:

[0018] (1) Mix the sulfate and the biomass, then carry out carbonization treatment, and then granulate to obtain the core;

[0019] (2) Mix the metal source and the biomass, then carry out pyrolytic carbonization to obtain the metal ion-modified porous carbon;

[0020] (3) Mix the core obtained in step (1) with the metal ion-modified porous carbon obtained in step (2), then granulate, and then carry out roasting.

[0021] Preferably, in step (1), the sulfate is selected from two or more of magnesium sulfate, calcium sulfate, potassium sulfate, sodium sulfate, iron sulfate, and lithium sulfate;

[0022] Preferably, the sulfate is a mixture of sodium sulfate, potassium sulfate, and magnesium sulfate. Based on the total amount of sodium sulfate, potassium sulfate, and magnesium sulfate being 100 wt%, the amount of sodium sulfate is 45 - 55 wt%, the amount of potassium sulfate is 5 - 15 wt%, and the amount of magnesium sulfate is 35 - 50 wt%.

[0023] Preferably, in step (1), the weight ratio of the biomass to the amount of the sulfate is 1:1 - 8, preferably 1:3 - 6.

[0024] Preferably, the operation of the carbonization treatment includes: under an inert atmosphere, heating to 600 - 1200 °C at a heating rate of 3 - 15 °C / min, and holding for 1 - 6 h.

[0025] Preferably, in step (2), the weight ratio of the metal source to the amount of the biomass is 0.2 - 5:1, preferably 0.5 - 2:1.

[0026] Preferably, in step (2), the metal source is selected from one or more of a calcium source, a magnesium source, and an iron source.

[0027] Preferably, in step (2), the operation of the pyrolytic carbonization includes: under an inert atmosphere, heating to 600 - 900 °C at a heating rate of 7 - 15 °C / min, and holding for 1 - 4 h.

[0028] Preferably, in step (3), the conditions of the roasting include: under an inert atmosphere, heating to 200 - 300 °C at a heating rate of 8 - 12 °C / min, and holding for 1 - 2 h.

[0029] The third aspect of the present invention provides an application of the above-mentioned metal ion-modified organic pollution biostimulation slow-release material in the remediation of organic polluted soil and groundwater.

[0030] Starting from the functional development and reuse of waste biomass, using biomass as the matrix, porous carbon is prepared by molten sulfate etching to obtain porous carbon loaded with sulfate, in order to explore the value of biochar itself in the field of slow-release function realization. Taking the porous carbon completely filled with sulfate as the slow-release center, the outer layer is wrapped with metal ion-modified porous carbon, so that after the sulfate in the inner layer is released, it can further reduce the free concentration of sulfate in the environment through processes such as anion-cation adsorption, complexation, and precipitation with it, realizing the effective slow-release control of the core agent sulfate, and forming a slow-release material with a core-shell structure of porous carbon loaded with sulfate @ metal ion-modified porous carbon. Description of the Drawings

[0031] Figure 1 is the process flow chart for the preparation of the metal ion-modified organic pollution biostimulation slow-release material;

[0032] Figure 2 is the structural schematic diagram of the test device used in Test Examples 2-4.

[0033] Description of the Reference Numerals

[0034] 1 Stirrer 2 Water storage container

[0035] 3 Peristaltic pump 4 Sample loading port

[0036] 5 Reaction soil column 6 Outlet water storage device

[0037] 7 Nitrogen gas balloon Detailed Embodiments

[0038] The following further elaborates on the detailed embodiments of the present invention with reference to the accompanying drawings. It should be understood that the detailed embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0039] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values and individual point values of each range, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0040] On the one hand, the present invention provides a metal ion-modified organic pollution biostimulation slow-release material, and the metal ion-modified organic pollution biostimulation slow-release material has a core-shell structure, wherein the inner core contains porous carbon loaded with sulfate, and the shell layer contains metal ion-modified porous carbon.

[0041] In the metal ion-modified organic pollution biostimulation slow-release material of the present invention, in the porous carbon loaded with sulfate, the sulfate is filled in the pores of the porous carbon with a pore diameter of 1-70 nm (the pores in the porous carbon are mainly mesopores and micropores), and a part of it is also loaded on the surface of the porous carbon, and can continuously dissolve and release the fixed sulfate radical in a certain environment, becoming the slow-release core of the sulfate radical. By granulating and coating (metal ion-modified porous carbon), the slow-release period of the sulfate radical is extended to prepare an organic pollution biostimulation slow-release material.

[0042] In the present invention, in order to reduce the melting temperature of sulfate and avoid the destruction of the structure of activated carbon due to too high reaction temperature, and to obtain a mixed molten salt with stable structure, preferably, in the porous carbon loaded with sulfate, the sulfate is selected from two or more of magnesium sulfate, calcium sulfate, potassium sulfate, sodium sulfate, iron sulfate and lithium sulfate.

[0043] In the present invention, in order to achieve a better slow-release effect, preferably, in the porous carbon loaded with sulfate, the pore diameter of the porous carbon is 1-40 nm.

[0044] Preferably, the raw material for preparing the porous carbon loaded with sulfate contains biomass.

[0045] In the metal ion-modified organic pollution biostimulation slow-release material of the present invention, the metal ions in the metal ion-modified porous carbon can be derived from metal salts (sulfates, hydrochlorides, carbonates, etc.), metal oxides and metal hydroxides, etc. On the one hand, these compounds can participate in the biomass carbonization process, and have a certain promoting effect on optimizing the pore structure of biomass carbon, increasing the specific surface area and enriching functional groups. At the same time, during the modification process, more metal ion loads can be introduced on the pore surface of biochar, thereby increasing the cation exchange capacity, and the loaded cations can also participate in the soil remediation and improvement process as functional elements.

[0046] In a preferred case, the metal ions are selected from one or more of calcium ions, magnesium ions and iron ions.

[0047] In the metal ion-modified organic pollution biostimulation slow-release material of the present invention, the raw material for preparing the metal ion-modified porous carbon contains biomass, the pores of the metal ion-modified porous carbon are mainly mesopores and micropores, and the pore diameter of the metal ion-modified porous carbon is 1-60 nm, preferably 1-20 nm.

[0048] In a preferred embodiment of the present invention, the metal ion-modified organic pollution biostimulatory slow-release material is spherical, and the inner core is also spherical. Preferably, the diameter of the metal ion-modified organic pollution biostimulatory slow-release material is 1-2.5 mm, preferably 1.25-2 mm; the diameter of the inner core is 0.5-1.25 mm, preferably 0.6-0.85 mm.

[0049] In a specific embodiment, the diameter of the metal ion-modified organic pollution biostimulatory slow-release material is 1.6 mm.

[0050] In a specific embodiment, the diameter of the inner core is 0.75 mm.

[0051] In the metal ion-modified organic pollution biostimulatory slow-release material of the present invention, the thickness of the shell layer is 0.35-0.65 mm, preferably 0.4-0.55 mm.

[0052] In a specific embodiment, the thickness of the shell layer is 0.425 mm.

[0053] The second aspect of the present invention provides a preparation method of the above-mentioned metal ion-modified organic pollution biostimulatory slow-release material, and its process flow chart is as Figure 1 shown, and the preparation method includes the following steps:

[0054] (1) Mix sulfate and biomass, then carry out carbonization treatment, and then granulate to obtain the inner core;

[0055] (2) Mix the metal source and biomass, and then carry out pyrolytic carbonization to obtain metal ion-modified porous carbon;

[0056] (3) Mix the inner core obtained in step (1) with the metal ion-modified porous carbon obtained in step (2), then granulate, and then carry out roasting.

[0057] In the preparation method of the present invention, the biomass used is common waste biomass in the art. In a specific embodiment, the biomass can be selected from one or more of fruit shells, straws, bamboo and wood, and municipal sewage sludge.

[0058] The present invention prepares porous carbon loaded with sulfate through the traditional molten salt carbonization process. In step (1), sulfate and biomass are mixed and then carbonized to obtain porous carbon loaded with sulfate. Among them, the molten salt (sulfate) can act as a template agent and a pore-forming agent during the carbonization process. Different from the traditional molten salt carbonization process for preparing porous carbon, in order to maintain a high saturation of sulfate radicals in the inner core of the metal ion-modified organic pollution biostimulatory slow-release material, no washing is carried out after the carbonization process is completed, so that the sulfate is retained.

[0059] Since the melting point of a single sulfate is relatively high, in order to obtain a sulfate with a low melting point, reduce the temperature in the molten salt carbonization process, and achieve a better slow-release effect, further preferably, in step (1), the sulfate is selected from two or more of magnesium sulfate, calcium sulfate, potassium sulfate, sodium sulfate, iron sulfate, and lithium sulfate. Further preferably, the sulfate is a mixture of sodium sulfate, potassium sulfate, and magnesium sulfate. Based on the total amount of sodium sulfate, potassium sulfate, and magnesium sulfate being 100 wt%, the amount of sodium sulfate is 45 - 55 wt%, the amount of potassium sulfate is 5 - 15 wt%, and the amount of magnesium sulfate is 35 - 50 wt%.

[0060] In a specific embodiment, in step (1), the sulfate is a mixture of sodium sulfate, potassium sulfate, and magnesium sulfate. Based on the total amount of sodium sulfate, potassium sulfate, and magnesium sulfate being 100 wt%, the amount of sodium sulfate can be 45 wt%, 47 wt%, 49 wt%, 50 wt%, 52 wt%, or 55 wt%, the amount of potassium sulfate can be 5 wt%, 7 wt%, 10 wt%, 13 wt%, or 15 wt%, and the amount of magnesium sulfate is 35 wt%, 37 wt%, 40 wt%, 43 wt%, 45 wt%, 47 wt%, or 50 wt%.

[0061] In a specific embodiment, the sulfate is a mixture of sodium sulfate, potassium sulfate, and magnesium sulfate. Based on the total amount of sodium sulfate, potassium sulfate, and magnesium sulfate being 100 wt%, the amount of sodium sulfate is 51 wt%, the amount of potassium sulfate is 6 wt%, and the amount of magnesium sulfate is 43 wt%.

[0062] In the preparation method of the present invention, in order to make the sulfate fill more fully, in step (1), the biomass can be pulverized and then mixed with the sulfate for grinding together to make the materials fully dispersed and evenly mixed, and then carbonized. There is no special requirement for the particle size of the pulverized biomass, and it can be preferably about 45 - 55 mesh. There is also no special requirement for the grinding time, as long as the materials can be fully mixed evenly. Preferably, the grinding time is about 5 minutes.

[0063] In step (1) of the present invention, the weight ratio of the biomass to the amount of the sulfate is 1:1 - 8, preferably 1:3 - 6, and specifically can be 1:3, 1:4, 1:5, or 1:6.

[0064] In a specific embodiment of step (1), the weight ratio of the biomass to the amount of the sulfate is 1:5.

[0065] In the carbonization process of step (1) of the present invention, the biomass begins to carbonize in advance to form porous carbon with certain pores. After reaching the melting temperature of the sulfate, the sulfate begins to melt, undergoes a phase change, and the molten sulfate enters the pores of the porous carbon and further etches the pore structure. At the same time, the molten salt ions also participate in the subsequent carbonization process in the form of a template agent to promote the formation of the porous carbon material. After the carbonization treatment, porous carbon loaded with sulfate is obtained.

[0066] In step (1), in order to achieve a better pore-forming effect, it is also necessary to further control the conditions of the carbonization treatment. In a preferred case, the operation of the carbonization treatment includes: heating to 600-1200 °C at a heating rate of 3-15 °C / min in an inert atmosphere and holding for 1-6 h.

[0067] In the operation of the carbonization treatment in step (1) of the present invention, due to the large difference in the melting properties of the sulfates used, the holding temperature is aimed at complete melting of the sulfate. In a preferred case, the holding temperature is preferably 600 °C - 1200 °C.

[0068] In a specific embodiment, in step (1), the heating rate can be 3 °C / min, 6 °C / min, 9 °C / min, 12 °C / min or 15 °C / min, and it can be heated to 600 °C, 700 °C, 800 °C, 900 °C, 1000 °C, 1100 °C or 1200 °C, and the holding time can be 1 h, 2 h, 3 h, 4 h, 5 h or 6 h.

[0069] In a specific embodiment of the present invention, in step (1), the operation of the carbonization treatment includes: heating to 700 °C at a heating rate of 5 °C / min and holding for 4 h.

[0070] In a preferred case in step (1) of the present invention, the porous carbon loaded with sulfate obtained after the carbonization treatment needs to be sufficiently ground to a particle size of 100-200 mesh and then granulated.

[0071] In the granulation process of step (1) of the present invention, it is necessary to spray a binder simultaneously to promote formation. There are no special requirements for the dosage of the binder used, as long as the final core size meets the corresponding requirements.

[0072] In step (2) of the present invention, the metal source is used to provide metal ions, which can be a conventional selection in the art. Specifically, it can be selected from one or more of metal oxides, metal salts (sulfates, hydrochlorides, carbonates), and metal hydroxides. On the one hand, the metal source can participate in the pyrolysis and carbonization process of biomass, which has a certain promoting effect on optimizing the pore structure of biomass carbon, increasing the specific surface area, and enriching functional groups. At the same time, during the modification process, more metal ion loads can be introduced onto the surface of biochar, thereby enhancing the cation exchange capacity. The loaded cations can also participate in the solidification and stabilization of sulfate through electrostatic attraction, complexation, etc., and extend the slow-release time.

[0073] In the preparation method of the present invention, also in step (2), in order to ensure sufficient mixing of the materials, the biomass can be crushed and then mixed with the metal source for grinding together to make the materials fully dispersed and evenly mixed, and then pyrolysis carbonization is carried out. There is no special requirement for the particle size of the crushed biomass, and it can be preferably about 45 - 55 mesh. There is also no special requirement for the grinding time, as long as the materials can be fully mixed evenly. Preferably, the grinding time is about 5 minutes.

[0074] Preferably, in order to achieve better effects, in step (2), the weight ratio of the amount of the metal source to the biomass is 0.2 - 5:1, preferably 0.5 - 2:1, and specifically can be 0.5:1, 1:1, 1.5:1, or 2:1.

[0075] In a specific embodiment, in step (2), the weight ratio of the amount of the metal source to the biomass is 2:1.

[0076] Preferably, in order to obtain a better slow-release effect, in step (2), the metal source is selected from one or more of calcium sources, magnesium sources, and iron sources.

[0077] In the present invention, the calcium source is used to provide calcium ions, and the calcium source can be a conventional selection in the art. For example, it can be selected from one or more of calcium oxides, calcium salts, and calcium hydroxides. Specifically, the calcium source can be selected from one or more of CaO, CaCO3, CaCl2, CaSO4, and Ca(OH)2.

[0078] In the present invention, the magnesium source is used to provide magnesium ions, and the magnesium source can be a conventional selection in the art. For example, it can be selected from one or more of magnesium oxides, magnesium salts, and magnesium hydroxides. Specifically, the calcium source can be selected from one or more of MgO, MgCO3, MgCl2, MgSO4, and Mg(OH)2.

[0079] In the present invention, the iron source is used to provide iron ions, and the iron source can be a conventional selection in the art. For example, it can be selected from one or more of iron oxides, iron salts, and iron hydroxides. Specifically, the iron source can be selected from one or more of Fe2O3, Fe2(CO3)3, FeCl3, Fe2(SO4)3, and Fe(OH)3.

[0080] In a preferred case, the metal source is a mixture of CaO, MgO, and Fe3O4, and the weight ratio of CaO, MgO, and Fe3O4 is 1.4 - 3:1:1, preferably 1.4 - 2:1:1, and specifically can be 1.4:1:1, 1.6:1:1, 1.8:1:1, or 2:1:1.

[0081] In a specific embodiment, in step (2), the weight ratio of the mixture of CaO, MgO, and Fe3O4 as the metal source is 2:1:1.

[0082] In step (2), in order to achieve a better pore-forming effect, it is also necessary to further control the pyrolysis carbonization conditions. In a preferred case, the pyrolysis carbonization operation includes: heating to 600 - 900 °C at a heating rate of 7 - 15 °C / min under an inert atmosphere and holding for 1 - 4 h.

[0083] In a specific embodiment, in step (2), the heating rate can be 7 °C / min, 10 °C / min, 12 °C / min, or 15 °C / min, and it can be heated to 600 °C, 700 °C, 800 °C, or 900 °C, and the holding time can be 1 h, 2 h, 3 h, or 4 h.

[0084] In a specific embodiment of the present invention, in step (2), the pyrolysis carbonization operation includes: heating to 800 °C at a heating rate of 10 °C / min and holding for 3 h.

[0085] In step (2) of the present invention, since the material obtained after pyrolysis carbonization may still contain unreacted metal source and unfixed metal ions, after the pyrolysis carbonization is completed, it is also necessary to wash the material obtained by pyrolysis carbonization to remove the unreacted metal source and unfixed metal ions, release the pores of the porous carbon, and then dry it to obtain the metal ion-modified porous carbon.

[0086] In step (2) of the present invention, water is used to wash the material obtained by pyrolysis carbonization multiple times, and the washing operation includes: placing the material in water and soaking for 10 min at 30 °C.

[0087] In the preferred case of step (2) of the present invention, in order to improve the washing efficiency and impurity removal effect, the material obtained by pyrolysis carbonization can be washed alternately with hydrochloric acid solution and water. The operation of washing with hydrochloric acid solution is the same as that of washing with water, that is, the operation of washing with hydrochloric acid solution includes: placing the material in hydrochloric acid solution and soaking it at 30 °C for 10 min.

[0088] In a specific embodiment, the concentration of the hydrochloric acid solution is 0.1 mol / L.

[0089] In step (2) of the present invention, there is no special requirement for the number of washing times. When performing the washing operation, the washing can be stopped when the pH value of the system is neutral.

[0090] In the preferred case of step (3) of the present invention, the metal ion-modified porous carbon obtained in step (2) also needs to be sufficiently ground to 100-200 mesh, and then mixed with the core obtained in step (1) for granulation to form a coating layer of metal ion-modified porous carbon on the surface of the core, obtaining a composite microsphere with a core-shell structure, and then performing calcination to finally obtain the metal ion-modified organic pollution biostimulation slow-release material of the present invention.

[0091] During the granulation process in step (3) of the present invention, a binder also needs to be sprayed simultaneously to promote molding. There is no special requirement for the dosage of the binder used, as long as the thickness of the shell layer of the finally obtained metal ion-modified organic pollution biostimulation slow-release material meets the corresponding requirements.

[0092] In the invention, there is no special requirement for the selection of the binder, as long as it can promote bonding and molding. In a specific embodiment, the binder is an aqueous solution of bentonite with a concentration of 15 wt%. During the calcination process, the bentonite undergoes carbonization to form a functional component of the material, and a metal ion-modified organic pollution biostimulation slow-release material with sulfate groups can be obtained after the calcination is completed.

[0093] In the preferred case of the present invention, in step (3), there is no special requirement for the dosages of the core obtained in step (1) and the metal ion-modified porous carbon obtained in step (2), as long as the size and the thickness of the shell layer of the obtained metal ion-modified organic pollution biostimulation slow-release material meet the corresponding thickness requirements.

[0094] The purpose of the calcination in step (3) of the present invention is to finally form and solidify the material, and the temperature of the calcination operation should not be too high, and it should be lower than the sulfate melting temperature to avoid the melting and flowing out of the core sulfate. Therefore, in the preferred case, in order to obtain a better slow-release effect, the conditions of the calcination in step (3) include: in an inert atmosphere, heating up to 200-300 °C at a heating rate of 8-12 °C / min and holding for 1-2 h.

[0095] In the specific implementation of step (3), the heating rate of the roasting can be 8 °C / min, 9 °C / min, 10 °C / min, 11 °C / min or 12 °C / min, and it can be heated to 200 °C, 220 °C, 240 °C, 260 °C, 280 °C or 300 °C. The heat preservation time can be 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h or 2 h.

[0096] The present invention uses the waste biomass carbonization product as the development matrix, and utilizes the structural and functional properties of the porous carbon prepared from biomass to achieve drug slow release. During the carbonization process, the core drug layer is combined with the traditional activation-molten salt carbonization method for preparing porous carbon without washing, and the core drug layer is directly obtained in one step. The "coating" shell layer is modified with metal ions, and the release of the inner layer sulfate is controlled through the precipitation, ion exchange, coordination complexation, etc. of the shell layer metal ions, and the slow release of the core drug slow release layer is controlled to form a biomass-based carbon microsphere with sulfate slow release. When the inner layer sulfate begins to be released, the outer layer metal ion-modified porous carbon on the one hand prolongs the sulfate release channel, and on the other hand can interact with the sulfate released from the inner layer through processes such as electrostatic attraction, anion exchange, complexation, ligand exchange and chemical precipitation, reducing the free concentration of sulfate in the environment. The slow release concentration of the long-acting slow release repair material can still reach 40 ppm at 220 d. It is not difficult to speculate from the change of the concentration during the dosing process that the slow release period is estimated to reach more than 250 days.

[0097] The present invention pre-obtains the structural units of the core and shell carbon by molten salt thermal carbonization, controls the addition ratio of the core-shell components for compounding and granulation, and forms a composite material with a core-shell structure of porous carbon loaded with sulfate @ metal ion-modified porous carbon. The molten salt is used to etch the biomass carbon to form pores, and after the molten salt thermal carbonization is completed, no rinsing is carried out, and the biomass porous carbon with completely filled internal pores with sulfate is obtained. The realization of sulfate slow release is based on the fact that the molten salt diffuses into the large, medium and small pores of the porous carbon during the etching process and releases relatively slowly. In addition, the metal ion-modified porous carbon is designed for coating treatment. When the sulfate is released and then passes through the coating layer, in addition to the porous structure prolonging the action path of sulfate release, the surface of the metal ion-modified porous carbon can also interact with sulfate through processes such as electrostatic attraction, anion exchange, complexation, ligand exchange and chemical precipitation, reducing the free concentration of sulfate in the environment and further prolonging the release period to achieve a better sulfate slow release effect.

[0098] The third aspect of the present invention provides an application of the above-mentioned metal ion-modified organic pollution biostimulation slow release material in the repair of organic polluted soil and groundwater.

[0099] The biochar in the present invention has a stable structure. Biochar is a porous solid formed by heat-treating waste biomass at a certain temperature. Its aromatic structure ensures its biological and chemical stability and is not easily mineralized and decomposed by microorganisms in the soil. Its porous structure endows it with more functionalizable characteristics, and its surface characteristic structure makes it have great transformation value in the field of adsorption stability. Taking biochar as the matrix, through technical design based on its structure and surface characteristics, biochar with a certain drug slow-release function is obtained. The slow-released drug can participate in the remediation process of contaminated soil, and the biochar matrix after slow-release can continue to play a certain role in the process of soil improvement. By adding the slow-release function, biochar is transformed into a soil conditioner with a certain remediation function. The modification of biochar with metal compounds has a certain promoting effect on optimizing the pore structure, increasing the specific surface area, and enriching the functional groups of biochar. The modification process can also achieve multi-metal loading on the biochar surface and improve the cation exchange capacity. At the same time, the loaded cations can also participate in the soil remediation and improvement process as functional elements. On the one hand, the present invention functionalizes waste biomass into a product with improved quality and increased efficiency for solving soil pollution. On the other hand, it directly contributes to the overall goal of carbon fixation and emission reduction in the form of soil carbon sequestration.

[0100] The raw material used in the present invention is waste biomass, which is transformed through technical means to achieve the value-added recovery of solid waste. The product is a bio-stimulating material with slow-release sulfate, which can be used in pollutant removal scenarios (such as soil, wastewater, and waste residue) with sulfate-reducing bacteria as the main target. The slow-release material can provide electron acceptors for the long-term life activities of sulfate-reducing bacteria in the soil. Through sulfate-reducing bacteria as an intermediary, organic pollutants can be degraded, and the sulfate is reduced to generate S 2- , which can stabilize heavy metals in the environment. The biochar matrix after slow-release can continue to play a certain role in the process of soil improvement, directly contributing to the overall goal of carbon fixation and emission reduction, and has great economic value and practical significance.

[0101] The present invention will be described in detail below through examples, but the scope protected by the present invention is not limited thereto.

[0102] Hereinafter, room temperature refers to 25 °C, and the waste straw biomass used comes from corn straw.

[0103] Example 1

[0104] (1) Sodium sulfate, potassium sulfate and magnesium sulfate are fully mixed to obtain a mixed sulfate, wherein the total amount of sodium sulfate, potassium sulfate and magnesium sulfate is 100wt%, the amount of sodium sulfate is 51wt%, the amount of potassium sulfate is 6wt%, and the amount of magnesium sulfate is 43wt%. The waste straw biomass is crushed to 50 mesh by a pulverizer to obtain waste straw biomass powder, and then the waste straw biomass powder is mixed with the mixed sulfate in a weight ratio of 1:1, fully ground for 5min, and then placed in a tubular furnace for carbonization treatment. The carbonization treatment operation includes: heating to 700°C at a heating rate of 5°C / min under a N2 atmosphere, and keeping at 700°C for 3h to obtain porous carbon loaded with sulfate;

[0105] (2) CaO, MgO and Fe3O4 are mixed in a weight ratio of 2:1:1 to obtain a metal source, and the waste straw biomass is crushed to 50 mesh by a pulverizer to obtain waste straw biomass powder. The metal source and the waste straw biomass powder are mixed in a weight ratio of 2:1, fully ground for 5 minutes, and then placed in a tube furnace for pyrolysis carbonization. The pyrolysis carbonization operation includes: heating to 800°C at a heating rate of 10°C / min under N2 atmosphere, and keeping at 800°C for 2 hours, and then cooling to room temperature, and washing alternately with a hydrochloric acid solution with a concentration of 0.1 mol / L and deionized water (the operation of washing with a hydrochloric acid solution includes: placing the material in a hydrochloric acid solution and soaking it at 30°C for 10 minutes; the operation of washing with deionized water includes: placing the material in deionized water and soaking it at 30°C for 10 minutes). When the pH value of the system is neutral, the washing is stopped, and the washed material is dried to obtain a porous carbon modified with metal ions;

[0106] (3) The porous carbon loaded with sulfate and the porous carbon modified with metal ions were ground to a particle size of 200 mesh, respectively. The ground porous carbon loaded with sulfate was first granulated using a disc granulator. During the granulation process, a 15 wt% bentonite aqueous solution was sprayed to promote molding. When the particle size grew to 0.75 mm, an inner core was obtained. The inner core was placed in the ground porous carbon modified with metal ions and mixed. The granulation was continued until the particle size was about 1.6 mm (a 15 wt% bentonite aqueous solution was sprayed to promote molding during the granulation process) to obtain composite microspheres with a core-shell structure.

[0107] (4) The composite microspheres are placed in a tubular furnace under a nitrogen atmosphere for roasting. Among them, the roasting conditions are as follows: under an N2 atmosphere, the temperature is raised to 200 °C at a heating rate of 10 °C / min, held at 200 °C for 2 h, and after roasting, a metal ion-modified organic pollution biostimulation slow-release material M1 with a core-shell structure is obtained. The metal ion-modified organic pollution biostimulation slow-release material is spherical, with a diameter of 1.6 mm. The inner core is spherical in shape, with a diameter of 0.75 mm, and the shell thickness is 0.425 mm. The metal ion-modified organic pollution biostimulation slow-release material has a core-shell structure, where the inner core is porous carbon loaded with sulfates, and the shell layer is metal ion-modified porous carbon.

[0108] Example 2

[0109] Implemented according to the method of Example 1, the difference is that in step (1), the weight ratio of waste straw biomass powder to the mixed sulfates is 1:2, and a metal ion-modified organic pollution biostimulation slow-release material M2 is obtained.

[0110] Example 3

[0111] Implemented according to the method of Example 1, the difference is that in step (1), the weight ratio of waste straw biomass powder to the mixed sulfates is 1:3, and a metal ion-modified organic pollution biostimulation slow-release material M3 is obtained.

[0112] Example 4

[0113] Implemented according to the method of Example 1, the difference is that in step (1), the weight ratio of waste straw biomass powder to the mixed sulfates is 1:4, and a metal ion-modified organic pollution biostimulation slow-release material M4 is obtained.

[0114] Example 5

[0115] Implemented according to the method of Example 1, the difference is that in step (1), the weight ratio of waste straw biomass powder to the mixed sulfates is 1:5, and a metal ion-modified organic pollution biostimulation slow-release material M5 is obtained.

[0116] Example 6

[0117] Implemented according to the method of Example 5, the difference is that in step (1), the heating rate is 10 °C / min, and in step (2), the heating rate is 15 °C / min, and a metal ion-modified organic pollution biostimulation slow-release material M6 is obtained.

[0118] Example 7

[0119] It was carried out according to the method of Example 5, except that in step (1), the heat preservation temperature was 800 °C, and in step (2), the heat preservation temperature was 900 °C, to obtain the metal ion-modified organic pollution biostimulation slow-release material M7.

[0120] Example 8

[0121] It was carried out according to the method of Example 5, except that in step (1), the heat preservation time was 4 h, and in step (2), the heat preservation time was 3 h, to obtain the metal ion-modified organic pollution biostimulation slow-release material M8;

[0122] The porous carbon loaded with sulfate obtained in step (1) of this example was fully soaked and rinsed in water to completely dissolve and remove the sulfate. After drying the porous carbon after removing the sulfate, pore size characterization was carried out on it by a physical adsorption instrument. It was found that the pore size distribution of the porous carbon was 1 - 21 nm, with a relatively large proportion of mesopores and a secondary micropore distribution; through scanning electron microscopy and energy spectrum analysis, the shell layer (metal ion-modified porous carbon) of M8 was characterized, and it was found that the surface of the modified porous carbon presented a rough surface, and the metal ions were evenly distributed on the surface of the porous carbon. Through pore size analysis of the shell layer by a physical adsorption instrument, it was found that its pore size distribution was concentrated in 1 - 19 nm, with a relatively large proportion of mesopores and a secondary micropore distribution.

[0123] Example 9

[0124] It was carried out according to the method of Example 5, except that in step (1), the heat preservation time was 5 h, and in step (2), the heat preservation time was 4 h, to obtain the metal ion-modified organic pollution biostimulation slow-release material M9.

[0125] Example 10

[0126] It was carried out according to the method of Example 8, except that in step (2), the metal source and the waste straw biomass powder were mixed in a weight ratio of 1:3 to obtain the metal ion-modified organic pollution biostimulation slow-release material M10.

[0127] Example 11

[0128] It was carried out according to the method of Example 8, except that in step (2), the metal source and the waste straw biomass powder were mixed in a weight ratio of 1:2 to obtain the metal ion-modified organic pollution biostimulation slow-release material M11.

[0129] Example 12

[0130] It was implemented according to the method of Example 8, except that in step (2), the metal source and the waste straw biomass powder were mixed at a weight ratio of 1:1 to obtain the metal ion-modified organic pollution biostimulation slow-release material M12.

[0131] Example 13

[0132] It was implemented according to the method of Example 8, except that in step (2), the metal source was CaO to obtain the metal ion-modified organic pollution biostimulation slow-release material M13.

[0133] Example 14

[0134] It was implemented according to the method of Example 8, except that in step (2), the metal source was MgO to obtain the metal ion-modified organic pollution biostimulation slow-release material M14.

[0135] Example 15

[0136] It was implemented according to the method of Example 8, except that in step (2), the metal source was Fe3O4 to obtain the metal ion-modified organic pollution biostimulation slow-release material M15.

[0137] Comparative Example 1

[0138] It was implemented according to the method of Example 1, except that no core-shell structure was prepared, and the materials were directly subjected to ordinary blending granulation, that is, the ground porous carbon loaded with sulfate and the ground metal ion-modified porous carbon were mixed evenly at a weight ratio of 1:7 and then placed in a disk granulator for granulation until the particle size increased to 1.6 mm. During the granulation process, an aqueous bentonite solution with a concentration of 15 wt% was sprayed to promote shaping, obtaining the metal ion-modified organic pollution biostimulation slow-release material D1.

[0139] Test Example 1

[0140] The 24-hour sulfate slow-release rate W of M1-M15 and D1 was measured respectively, and the calculation formula of W is as follows:

[0141]

[0142] Among them,

[0143] R 24 is the amount of sulfate precipitated in the aqueous phase in the constant-speed shaker for 24 h under light-shielding conditions.

[0144] T is the total amount of sulfate fixed by the slow-release material.

[0145] The test implementation process is as follows: First, place the metal ion-modified organic pollution biostimulation slow-release material in ultrapure water and rinse it for 30 minutes, then dry it thoroughly to remove the un-fixed sulfate radicals. Take 2 g of the rinsed and dried metal ion-modified organic pollution biostimulation slow-release material and place it in a conical flask containing 250 mL of ultrapure water. Under light-shielded conditions, continuously oscillate it in a shaker at 150 rad / min for 24 hours, and measure the sulfate radical concentration in the supernatant. Record this concentration as R 24 . Take 10 g of the rinsed and dried metal ion-modified organic pollution biostimulation slow-release material and place it in an alumina crucible. Heat it to 1000 °C in a muffle furnace and burn it thoroughly for 2 hours to release the fixed sulfate radicals. After cooling, take out the burned sample and dissolve it again, measure the sulfate radical concentration in the supernatant, and record this concentration as T, which is the total amount of fixed sulfate radicals in the slow-release material. The test method for sulfate radical concentration refers to HJ84-2016 "Determination of Inorganic Anions in Water - Ion Chromatography Method".

[0146] The results are shown in Table 1

[0147] Table 1

[0148] Sample M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13 M14 M15 D1 Sustained release rate W / % 35.82 37.43 34.69 33.28 32.15 35.43 36.22 30.29 31.89 33.59 31.37 30.79 32.54 31.78 28.99 41.59

[0149] Test Example 2

[0150] Adopt the test device as Figure 1 shown to simulate the slow-release effect of the metal ion-modified organic pollution biostimulation slow-release material in the soil and groundwater environment. The test device is as Figure 2 shown. The device includes: a water storage container 2, a stirrer 1, a peristaltic pump 3, a reaction soil column 5 (with a length of 30 cm and a diameter of 10 cm), an outlet water storage container 6, and a nitrogen gas balloon 7; among them, the stirrer 1, the water storage container 2, the peristaltic pump 3, the reaction soil column 5, and the outlet water storage container 6 are connected in sequence. The reaction soil column 5 is provided with a sample loading port 4, an inlet and an outlet. The inlet is connected to the peristaltic pump 3, and the outlet is connected to the outlet water storage container 6. The nitrogen gas balloon 7 is connected to the water storage container 2;

[0151] The reaction soil column 5 of the test device is filled with a mixed filler of humic acid, soil, and quartz sand. After loading the metal ion-modified organic pollution biostimulation slow-release material through the sample loading port 4, it is laid flat on the entire cross-section. As Figure 2 shown, after the metal ion-modified organic pollution biostimulation slow-release material is loaded through the sample loading port 4, the internal flow of soil and groundwater can be simulated in the device, and relevant indicators can be monitored to evaluate the slow-release performance of the material.

[0152] Slow-release performance test: After the metal ion-modified organic pollution biostimulation slow-release material is loaded through the sample loading port 4, the filling thickness of the organic pollution biostimulation slow-release material in the reaction soil column 5 is 1 cm. Tap water is contained in the lower part of the water storage container 2. At the same time, nitrogen is filled into the water storage container 2 through the nitrogen gas balloon 7, so that the upper part of the water storage container 2 is filled with nitrogen to remove the oxygen in the upper headspace of the aqueous solution. The tap water in the water storage container 2 is continuously injected into the reaction soil column 5 from the water inlet of the reaction soil column 5 at a certain rate through the peristaltic pump 3 to simulate the permeable reactive wall technology. The outflow concentration of sulfate in the effluent of the water storage device 6 at the outlet (i.e., sulfate at the outlet of the reaction soil column 5) is regularly monitored to evaluate the slow-release effect of sulfate in the material, and the slow-release time of the material in the simulated soil groundwater is determined. During the test, the water intake of the peristaltic pump 3 is adjusted to make the effluent rate of the water storage device 6 at the outlet 3 mL / h.

[0153] Among them, the outflow concentration of sulfate in the effluent of the water storage device 6 at the outlet monitored at different times after injecting the metal ion-modified organic pollution biostimulation slow-release material is shown in Table 2.

[0154] Table 2

[0155]

[0156]

[0157] By analyzing and comparing the slow-release rates and sulfate concentrations during the slow-release process of M1-M5 in combination with Table 1 and Table 2, it is not difficult to find that as the sulfate incorporation ratio increases, the slow-release effect becomes better. Among them, for M5 at the 220th day, the sulfate concentration in the effluent also reaches above 35 ppm;

[0158] By comparing M5 and M6, it can be obtained that when the heating rate is 5 °C / min during the preparation of the porous carbon loaded with sulfate and the heating rate is 10 °C / min during the preparation of the metal ion-modified porous carbon, that is, the M5 sample has an ideal slow-release effect;

[0159] By comparing M5 and M7, it can be obtained that when the holding temperature increases during the preparation process, the slow-release effect gradually becomes worse;

[0160] By comparing M5, M8, and M9, it can be obtained that a certain holding time can improve the slow-release effect, but too long a holding time may cause the destruction of the carbon structure and affect the slow-release effect. M8 shows a better effect;

[0161] By comparing M8, M10, M11, and M12, it can be obtained that when the outer layer metal ion loading changes (i.e., the metal source and biomass dosage change), the slow-release performance also shows a certain fluctuating change. Within a certain range, the slow-release period tends to extend as the metal ion loading increases;

[0162] The sulfate release effects caused by different metal loadings are different. The influence of calcium loading on the sulfate release performance is mainly reflected in coprecipitation. Metals such as iron and magnesium can form coordination structures with carbon to adsorb sulfate and thus play a slow-release role. By comparing the slow-release performances of M13 - M15, it is not difficult to find that when using Fe3O4 as the metal source to modify porous carbon, the resulting composite microspheres have the best slow-release performance. However, in addition to its main functional properties, the present invention also considers providing metabolic activity elements for microorganisms from multiple perspectives. After the initial slow release, the metal ion-modified organic pollution biostimulation slow-release material of the present invention is basically a soil improvement material. Therefore, considering the slow-release performance and ensuring the multi-faceted supply of functional elements, the preferred best metal source of the present invention is still a mixture of CaO, MgO, and Fe3O4. Using this metal source can establish a multi-source composite and strongly adaptable system;

[0163] Comparing M8 and D1, it can be seen that compared with ordinary blending, the core-shell structure of the present invention can more effectively ensure the slow-release performance of the slow-release material. Among them, the slow-release concentration of M8 can still reach 40 ppm at 220 d. According to the change of concentration during the dosing process, it is not difficult to speculate that its slow-release period is estimated to reach more than 250 days.

[0164] Test Example 3

[0165] The actual pollutant removal performance of the organic biostimulation slow-release material was detected using the same test device as in Test Example 2.

[0166] The following polluted aquifer sediment used was obtained from the petroleum hydrocarbon-polluted aquifer sediment in the contaminated soil of an enterprise site. The initial concentration of petroleum hydrocarbons was determined to be 103 mg / kg using GS-MS, and the water content of the polluted aquifer sediment was 32%. The taken polluted aquifer sediment was placed in a tube and directly placed in a glove box after being sent to the laboratory, avoiding air contact during the whole process.

[0167] The reaction soil column 5 was filled with polluted aquifer sediment. After loading M8 through the sample loading port 4 and spreading it evenly over the entire cross-section, the filling thickness of the sample in the reaction soil column 5 was 1 cm, with polluted aquifer sediment on both sides. The lower part of the water storage container 2 was filled with an aqueous solution of petroleum hydrocarbons with a concentration of 100 mg / L. Similarly, nitrogen was filled into the water storage container 2 through the nitrogen gas balloon 7, so that the upper part of the water storage container 2 was filled with nitrogen, removing the oxygen in the headspace above the aqueous solution of petroleum hydrocarbons. The aqueous solution of petroleum hydrocarbons in the water storage container 2 was continuously injected into the reaction soil column 5 from the water inlet of the reaction soil column 5 at a certain rate through the peristaltic pump 3, simulating the permeable reactive barrier technology. By regularly monitoring the data of the sulfate concentration and petroleum hydrocarbon pollutant concentration in the effluent water storage device 6 at the outlet, the organic pollution removal effect of the material was evaluated. During the test process, the water inflow of the peristaltic pump 3 was adjusted to make the effluent rate of the effluent water storage device 6 at the outlet 3 mL / h. The results are shown in Table 3.

[0168] Table 3

[0169] Number of dosing days d Concentration of petroleum hydrocarbon pollutants ppm Concentration of sulfate ion in effluent ppm 1 105 - 5 102 2.55 10 106 16.23 30 98 30.1 50 87 38.53 70 59 55.42 100 32 56.87 130 22 52.61 160 13 51.02 190 12 43.71 220 10 41.29

[0170] Test Example 4

[0171] The test was carried out according to the test method of Test Example 3, except that the pollutant was replaced with a benzene solution of 100 mg / kg instead of petroleum hydrocarbons, and the other steps were the same. The data of the sulfate concentration and benzene pollutant concentration in the water outlet water storage tank 6 obtained were monitored regularly, and the results are shown in Table 4.

[0172] Table 4

[0173] Number of dosing days d Concentration of benzene pollutants ppm Concentration of sulfate ion in effluent ppm 1 103 - 5 106 2.37 10 100 14.69 30 95 31.02 50 80 35.7 70 56 59.62 100 38 50.19 130 21 53.67 160 12 42.99 190 10 44.56 220 11 42.1

[0174] It can be seen from the changes in the pollutant and sulfate concentrations in Table 3 that in the first about 10 days after the addition of the material, the change in the pollutant concentration was small, basically remaining at about 100 ppm. On the one hand, this was caused by the heterogeneity in the mixing process of the sediment and the reagent in the early stage and the systematic error in the test process. On the other hand, the reason may be that the sulfate-reducing bacteria in the environment were still in an unexcited state at this stage and did not carry out life activities as the dominant strain; from the 10th day to the 100th day, after the adaptation period, the sulfate-reducing bacteria began to grow dominantly and continuously utilized the pollutant concentration inside the system for life activities. The increase in the sulfate concentration slowed down, and the pollutant concentration began to decrease sharply. By the 100th day, about 60%-70% of the pollutant degradation had been basically completed; in the later stage of the test, the pollutant concentration was basically at a low level, basically remaining at about a dozen ppm, and the degradation rate slowed down. The slow-release material was still carrying out sulfate slow-release, and the sulfate ions maintained at a high concentration for a certain period of time.

[0175] In Table 4, benzene was used as the degradation object, and the degradation trend of benzene during the sulfate slow-release process was investigated. The overall degradation effect was similar to that of petroleum hydrocarbons, which corroborated the wide applicability of the slow-release material.

[0176] Based on the above results, it can be obtained that the metal ion-modified organic pollution biostimulation slow-release material provided by the present invention has a better slow-release effect and can be applied to the remediation process of organic pollution soils such as petroleum hydrocarbons and benzene.

[0177] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A metal ion-modified organic pollution biostimulation slow-release material, characterized in that, The metal ion-modified organic pollution biostimulation sustained-release material has a core-shell structure, wherein the core contains porous carbon loaded with sulfate, and the shell layer contains metal ion-modified porous carbon.

2. The metal ion-modified organic pollution biostimulation sustained-release material according to claim 1, wherein Among the porous carbon loaded with sulfate, the sulfate is selected from two or more of magnesium sulfate, calcium sulfate, potassium sulfate, sodium sulfate, iron sulfate, and lithium sulfate.

3. The metal ion-modified organic pollution biostimulatory slow-release material according to claim 1, wherein The metal ions are selected from one or more of calcium ions, magnesium ions, and iron ions.

4. The metal ion-modified organic pollution biostimulation sustained-release material according to claim 1, wherein, Among the porous carbon loaded with sulfate, the pore size of the porous carbon is 1-70 nm, preferably 1-40 nm. Preferably, the raw material for preparing the porous carbon loaded with sulfate contains biomass.

5. The metal ion-modified organic pollution biostimulation sustained-release material according to any one of claims 1, 2 or 4, characterized in that, The pore size of the metal ion-modified porous carbon is 1-60 nm, preferably 1-20 nm. Preferably, the raw material for preparing the metal ion-modified porous carbon contains biomass.

6. The metal ion-modified organic pollution biostimulation sustained-release material according to claim 1, characterized in that, The diameter of the metal ion-modified organic pollution biostimulation sustained-release material is 1-2.5 mm, preferably 1.25-2 mm.

7. The metal ion-modified organic pollution biostimulation sustained-release material according to claim 1, characterized in that The diameter of the core is 0.5-1.25 mm, preferably 0.6-0.85 mm. Preferably, the thickness of the shell layer is 0.35-0.65 mm, preferably 0.4-0.55 mm.

8. The preparation method of the metal ion-modified organic pollution biostimulation slow-release material according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: (1) Mix sulfate and biomass, then carry out carbonization treatment, and then granulate to obtain the core. (2) Mix a metal source with biomass and then carry out pyrolytic carbonization to obtain metal ion-modified porous carbon. (3) Mix the core obtained in step (1) with the metal ion-modified porous carbon obtained in step (2), then granulate, and then carry out roasting.

9. The preparation method according to claim 8, wherein In step (1), the sulfate is selected from two or more of magnesium sulfate, calcium sulfate, potassium sulfate, sodium sulfate, iron sulfate, and lithium sulfate. Preferably, the sulfate is a mixture of sodium sulfate, potassium sulfate, and magnesium sulfate. And based on the total amount of sodium sulfate, potassium sulfate, and magnesium sulfate being 100 wt%, the amount of sodium sulfate is 45-55 wt%, the amount of potassium sulfate is 5-15 wt%, and the amount of magnesium sulfate is 35-50 wt%.

10. The preparation method according to claim 8 or 9, characterized in that, In step (1), the weight ratio of the biomass to the amount of the sulfate is 1:1-8, preferably 1:3-6. Preferably, the operation of the carbonization treatment includes: under an inert atmosphere, heating at a heating rate of 3-15 °C / min to 600-1200 °C, and holding for 1-6 h.

11. The preparation method according to claim 8, characterized in that, In step (2), the weight ratio of the metal source to the amount of the biomass is 0.2-5:1, preferably 0.5-2:

1.

12. The preparation method according to claim 8 or 11, characterized in that, In step (2), the metal source is selected from one or more of a calcium source, a magnesium source, and an iron source.

13. The preparation method according to claim 8, characterized in that, In step (2), the operation of the pyrolytic carbonization includes: under an inert atmosphere, heating at a heating rate of 7-15 °C / min to 600-900 °C, and holding for 1-4 h.

14. The preparation method according to claim 8, characterized in that, In step (3), the conditions for roasting include: under an inert atmosphere, heating at a heating rate of 8-12 °C / min to 200-300 °C, and holding for 1-2 h.

15. Use of the metal ion-modified organic pollution biostimulation sustained-release material according to any one of claims 1-7 in the remediation of organic-polluted soil and groundwater.

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