Method for in-situ synthesis of organic modified porous functional materials using coal gangue

Abstract

The present invention relates to the field of coal gangue utilization technology, there is provided a method for synthesizing organic modified porous functional materials using coal gangue in situ, including: coal gangue is crushed, sieved, and powder is calcined at 100 1000 DEG C to obtain a layered silicate mineral; 1 10g layered silicate mineral, 5 50g soluble silicate and / or soluble silicic acid, 3 30g metal compound and 40 400ml deionized water are mixed, stirred, and obtained suspension A after ultrasonic treatment reaction; a complexing agent is added afterwards, stirring is performed to obtain a precursor solution, which is transferred into a closed reactor, and a mixed product containing a solid and a liquid is obtained by reaction under 50 400 DEG C of temperature and 5 30MPa pressure conditions; solid-liquid separation is performed to obtain a solid organic modified porous functional material; 1 3wt% potassium permanganate aqueous solution is sprayed into by a nozzle. It is realized that pore is small, average control reaches nanometer level, and components such as metal elements and carbon are effectively utilized, and the waste of valuable metals and carbon is avoided to a great extent, and it is suitable for industrialized production.

Description

Technical Field

[0001] The present application relates to the technical field of coal gangue utilization, and in particular to a method for in-situ synthesis of organically modified porous functional materials using coal gangue. Background Art

[0002] After multiple coal mining and washing processes, coal gangue and other solid wastes are generated in large quantities. Gangue, a dark-gray rock with a low carbon content (10%-30%) and harder than coal, typically accounts for approximately 10-20% of coal production. Gangue solid waste has become the largest source of solid waste in my country, with the lowest comprehensive utilization rate. The accumulation of such waste not only pollutes the air and water but also poses safety risks, which has attracted significant public attention.

[0003] Gangue is primarily composed of kaolinite, quartz, calcite, pyrite, and illite, with a certain amount of organic matter and a small amount of mica. Its main elements include Si, Al, C, Ca, Fe, Mg, and K. Over the past few decades, extensive research has been conducted on the utilization of gangue, primarily focusing on landfill, building materials production, energy industry, and agriculture. Despite this, achieving high-value utilization of gangue remains a challenge. In the current dual-carbon context, achieving efficient and green utilization of gangue in a low-carbon economy is crucial.

[0004] Mineral composition analysis indicates that the composition of coal gangue varies with geographic location, but most gangue is primarily composed of kaolinite (Al2O3·2SiO2·2H2O), a hydrous aluminosilicate clay mineral. SiO2 and Al2O3 typically account for over 80% of the total composition. Clay minerals such as kaolinite are nano-layered silicates composed of a 1:1 or 1:2 ratio of silicon-oxygen tetrahedra to metal-oxygen octahedra. These tetrahedra and metal-oxygen octahedra are linked by Si-O-Si and Si-OM (M: Al, Fe, Mg) bonds, forming a nanosheet structure. For example, Chinese patent CN115196640A discloses a mesoporous silica material based on coal gangue and its preparation method, wherein a coal gangue-based silicon source, an organic carboxylic acid, anhydrous organic alcohol and a surfactant are mixed and reacted, and a mesoporous material is prepared through a series of steps including self-assembly treatment, centrifugation, drying, activation with an inorganic strong acid solution, and roasting. However, this method uses the silicon species extract obtained after the solid waste coal gangue is sequentially subjected to acid washing and dealuminization treatment under stirring and reflux, activation treatment with an inorganic strong alkali solution under high temperature and high pressure super(sub)critical conditions and dissolution treatment with an inorganic strong acid solution as the silicon source, that is, the coal gangue needs to be treated with acid washing, alkali treatment and other processes before being used as a raw material with the help of organic The selective and appropriate introduction of alcohols and organic carboxylic acids, combined with solvent thermal self-assembly, regulates the hydrolysis-polymerization degree of silicon species and the surface hydroxyl content, promoting their synergistic self-assembly with block copolymer non-ionic surfactants, and with the help of high-temperature hydrothermal polymerization treatment in a strong acid solution at a pH value close to the isoelectric point of silica, a mesoporous silica material with a highly uniform mesoporous channel structure and high hydrothermal stability is prepared; repeated modification with strong acids, strong bases and other additives is complex, the cross-use of acids and bases leads to a significant increase in usage, and it is only utilized from the perspective of raw material composition, and fails to be utilized from the perspective of coal gangue composition such as carbon-containing substances, layered crystal structure, etc.

[0005] Chinese patent CN115057458A discloses a method for preparing nano-alumina from coal gangue. Gangue loaded with an inorganic salt of alkali metal K, an inorganic salt of Na, or biomass is gasified or burned at high temperature to activate the gangue at high temperature. The resulting aluminum hydroxide precursor is then calcined, washed, acid-washed, and filtered to produce flaky alumina. The gasification or combustion temperature is 600-1000°C, and alkali metals are used as activators. Using an inorganic salt or biomass containing alkali metals as an activator can improve aluminum extraction efficiency and effectively reduce the thermal activation temperature. Based on the characteristics of the solution after acid dissolution, combined with the traditional molten salt method (MSS) for preparing flaky alumina, a mixed solution of KOH and NaOH is added to the acidic crude solution to adjust the pH and form molten salts K2SO4 and Na2SO4. The molten salts can be recovered and reused as an activator for coal gangue. Gangue loaded with inorganic salts of alkali metals K, Na, or biomass is gasified or burned at high temperatures to activate the gangue, a process that also consumes carbon in the gangue. However, this method primarily consumes carbon in the gangue through combustion, with the carbon used solely for combustion. Flake alumina, obtained through acid leaching and alkali solution, has low utilization rates of the gangue components, effectively utilizing only one component, alumina, and requires complex processes such as impurity removal.

[0006] Chinese patent CN112316924B discloses a gangue-based porous composite material, its preparation method, and application. By crushing, foaming, and modifying the gangue, a gangue-based porous composite material with a large specific surface area, strong heavy metal adsorption capacity, and excellent solid particulate removal efficiency is obtained. The composite material is heat-treated at 600°C for 4 hours, then removed and cooled at 25°C. After demolding, the green body is programmed to 1100°C in an air atmosphere and held at this temperature for 2 hours to obtain a gangue-based porous skeleton. This method, while obtaining the porous composite material through multiple heat treatments and the intermediate use of an external foaming agent for foaming, makes it difficult to maintain internal pores in the composite material, making it difficult to obtain an efficient porous adsorption material.

[0007] As can be seen from the above, while existing methods can impart adsorption properties to coal gangue, the preparation process is relatively complex. Extensive use of acid-base combinations and the addition of additives for pore creation make it difficult to increase the porosity within the material. The use of a single component in the coal gangue further complicates the process, further complicating the process by removing impurities, and making it difficult to effectively utilize components such as carbon in the coal gangue. Therefore, the present invention provides a new technology for in-situ synthesis of organically modified porous functional materials using coal gangue. This technology is currently lacking in the literature and has no precedent for its application. Summary of the Invention

[0008] To overcome the shortcomings of the existing technology, the present application provides a method for in-situ synthesis of organic modified porous functional materials using coal gangue, which achieves small pores, average control to the nanoscale, high pore volume, and large specific surface area. It can efficiently remove pollutants such as organic dyes, heavy metals, antibiotics, and phosphorus, and convert the mineral components in the coal gangue into porous functional materials in situ, effectively utilizing metal elements, carbon and other components, and largely avoiding the waste of valuable metals and carbon, making it suitable for industrial production.

[0009] The embodiment of the present application is implemented as follows:

[0010] This application example provides a method for in-situ synthesis of organically modified porous functional materials using coal gangue, comprising:

[0011] (1) Grinding and sieving the coal gangue, and calcining the powder at 100-1000°C for 2-24 hours to obtain layered silicate minerals;

[0012] (2) 1-10 g of layered silicate mineral, 5-50 g of soluble silicate and / or soluble silicic acid, 3-30 g of metal compound and 40-400 ml of deionized water are mixed, stirred, and then subjected to ultrasonic treatment in a cell crusher to obtain a suspension A;

[0013] (3) Add 0.05-5 g of complexing agent to suspension A, and then stir to obtain a uniform precursor solution;

[0014] (4) The precursor solution obtained above is transferred into a closed reactor and reacted at a temperature of 50-400°C and a pressure of 5-30 MPa for 1-30 hours to obtain a mixed product containing solid and liquid;

[0015] (5) performing solid-liquid separation on the mixed product obtained above to obtain a solid organic modified porous functional material;

[0016] In step (1), the gangue is crushed and sieved, and during the low-temperature calcination of the powder, a 1-3 wt% potassium permanganate aqueous solution is sprayed through a nozzle, the sprayed mass accounts for 0.1-0.2 wt% of the mass of the gangue, and the spraying time is 0.5-1 h.

[0017] Optionally, in step (1), the coal gangue is crushed and sieved, and the powder is calcined at a temperature of 195-296°C.

[0018] Optionally, in step (1), the gangue is crushed and sieved, and the powder is subjected to high-temperature calcination for 5-10 minutes before being subjected to low-temperature calcination. The calcination temperature is 850-945° C., and microwave-assisted heating is used.

[0019] Optionally, the kaolinite content in the layered silicate mineral obtained after calcining the coal gangue is not less than 40%; and the particle size of the powder after crushing the coal gangue is 48-200 μm.

[0020] Optionally, the soluble silicate is one or any combination of lithium silicate, sodium silicate, ammonium silicate, and potassium silicate, the soluble silicic acid is orthosilicic acid, and the added amount is such that the mass ratio of coal gangue to soluble silicate and / or soluble silicic acid is 1:(4.5-5.5); the metal compound is one or any combination of magnesium chloride, magnesium oxide, basic magnesium carbonate, zinc chloride, zinc sulfate, zinc nitrate, zinc dihydrogen phosphate, calcium oxide, calcium chloride, magnesium sulfate, magnesium nitrate, magnesium acetate, calcium halide, calcium carbonate, calcium nitrate, calcium chlorate, and calcium perchlorate, and the added amount is such that the mass ratio of coal gangue to the metal compound is 1:2.5-3.5; the complexing agent is one or any combination of nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and diethyltriacetic acid, and the mass concentration is 0.1-30%.

[0021] Optionally, the soluble silicate is lithium silicate, sodium silicate and potassium silicate, and based on the total mass of the soluble silicate, the ratio of lithium silicate: sodium silicate: potassium silicate is 1:(12-13):(13-14).

[0022] Optionally, the metal compound is magnesium oxide, zinc chloride and calcium oxide, and based on the total mass of the metal compound, the ratio of magnesium oxide: zinc chloride: calcium oxide is 1: (0.2-0.3): (1.3-1.5).

[0023] Optionally, the complexing agent is ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, and based on the total mass of the complexing agent, the ratio of ethylenediaminetetraacetic acid to diethylenetriaminepentaacetic acid is 1:(0.3-0.4).

[0024] Optionally, the amount of deionized water added is such that the mass ratio of gangue to deionized water is 1:35-45.

[0025] Optionally, the pH value of the suspension A is between 5 and 12, and an alkaline metal compound may be added to adjust the pH.

[0026] Beneficial effects include:

[0027] The method provided by the present invention utilizes coal gangue to synthesize organic modified porous functional materials in situ. Layered silicate minerals are prepared from coal gangue, which are directly mixed with soluble silicates and / or soluble silicic acid, metal compounds, organic complexing agents and water, and then heated and pressurized to react to obtain solid organic modified porous functional materials. This method is conducive to forming a multi-level pore structure and increasing the generation of carbon pores. No acid or alkali treatment is required, thus avoiding the problems of impurity dissolution and large acid and alkali consumption during acid and alkali treatment. The process is simplified. The mineral components and metals in the coal gangue are synthesized in situ into organic modified porous functional materials in a one-pot method, so that the materials have characteristics such as high specific surface area and porous structure.

[0028] Low-temperature calcination is primarily used to reduce carbon combustion losses, which is beneficial for carbon retention and the generation of porous carbon such as activated carbon. This improves porosity, transforming the layered silicate mineral into a fine nanoscale pore structure rich in porous silica and porous carbon (i.e., a pore structure of a silica-C composite structure). Layered silicates also possess a richer Si-O-Al skeleton, increasing their load capacity and stability, thereby improving adsorption and metal loading capacity. The value of carbon combustion is significantly lower than its value as an adsorption material, significantly increasing the application value of coal gangue and reducing carbon emissions.

[0029] During the low-temperature calcination process of coal gangue powder, a 1-3wt% potassium permanganate aqueous solution is sprayed into the coal gangue, and water reacts with the carbon in the coal gangue to produce water gas, generating hydrogen, CO and associated water vapor, which can effectively improve the circulation of gas in the coal gangue layered structure, facilitate the formation of mesopores with moderate pores, and improve the generation of carbonaceous pores. At the same time, low-content potassium permanganate is sprayed into the coal gangue surface for a long time, decomposes into MnO2 under heat, and accompanies the pore formation process, realizing the loading of MnO2 on the surface and inside of the coal gangue, thereby improving its load dispersion uniformity and loading rate. The generated oxygen reacts with carbon, and reacts with water and carbon in the coal gangue to produce water gas, which is more conducive to the partial consumption of carbon in the coal gangue. The generated gas promotes the formation of pores, which is beneficial to improving the adsorption performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 SEM image of the organically modified porous functional material of Example 1;

[0032] Figure 2TEM image of the organically modified porous functional material of Example 1;

[0033] Figure 3 N2 adsorption-desorption isotherms of the organically modified porous functional material of Example 1;

[0034] Figure 4 Pore ​​size distribution curve of the organically modified porous functional material of Example 1;

[0035] Figure 5 XRD curve of the organically modified porous functional material of Example 1.

[0036] Explanation of the attached table:

[0037] Table 1 shows the pore structure parameters of organically modified porous functional materials;

[0038] Table 2 shows the adsorption performance of organic modified porous functional materials for organic dyes, heavy metals, tetracycline hydrochloride and phosphorus. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] Those skilled in the art will understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which this invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless specifically defined as such, will not be interpreted in an idealized or overly formal sense.

[0041] Those skilled in the art will understand that, unless otherwise stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items. The raw materials used below, unless otherwise specified, are all from commercially available products. For performance testing, please refer to national standards or industry standards.

[0042] The preparation process for recycling coal gangue is relatively complicated, with a large amount of acid and alkali used, and external additives added to form pores. The porosity in the material is difficult to increase, the use of a single component of coal gangue, and impurity removal further complicate the process, and components such as carbon in coal gangue are difficult to effectively utilize. Therefore, an embodiment of the present invention provides a method for in-situ synthesis of organically modified porous functional materials using coal gangue.

[0043] The features and performance of the present invention are further described in detail below with reference to the embodiments:

[0044] The embodiment of the present invention provides a method for in-situ synthesis of organically modified porous functional materials using coal gangue, comprising:

[0045] (1) The coal gangue is crushed and sieved, and the powder is calcined at 100-1000°C (optionally 100°C, 105°C, 134°C, 146°C, 157°C, 166°C, 173°C, 184°C, 196°C, 211°C, 234°C, 246°C, 271°C, 286°C, 291°C, 351°C, 378°C, 394°C, 411°C, 423°C, 567°C, 678°C, 689°C, 723°C, 754°C, 768°C, 778°C, 798°C, 854°C, 873°C, 946°C, 967°C, 971°C, 985°C, 1000°C, etc.) for 2-24h to obtain layered silicate minerals.

[0046] (2) 1-10 g (optionally 1 g, 2 g, 3 g, 4 g, 5 g, 6 g, 7 g, 8 g, 9 g, 10 g, etc.) of layered silicate mineral, 5-50 g (optionally 5 g, 8 g, 11 g, 13 g, 16 g, 28 g, 35 g, 42 g, 47 g, 50 g, etc.) of soluble silicate and / or soluble silicic acid, 3-30 g (optionally 3 g, 8 g, 11 g, 13 g, 16 g, 22 g, 24 g, 26 g, 28 g, 30 g, etc.) of metal compound and 40-400 ml of deionized water are mixed, stirred, and subjected to ultrasonic treatment in a cell crusher to obtain a suspension A.

[0047] (3) Add 0.05-5 g (optionally 0.05 g, 0.17 g, 0.29 g, 0.38 g, 0.74 g, 1.1 g, 1.7 g, 2.1 g, 2.4 g, 2.7 g, 3.3 g, 3.6 g, 3.9 g, 4.1 g, 4.5 g, 4.6 g, 4.9 g, 5 g, etc.) of complexing agent to suspension A, and then stir to obtain a uniform precursor solution.

[0048] (4) The precursor solution obtained above is transferred into a closed reactor and heated at a temperature of 50-400°C (optionally 50°C, 53°C, 57°C, 64°C, 69°C, 74°C, 75°C, 78°C, 86°C, 89°C, 93°C, 96°C, 98°C, 107°C, 115°C, 143°C, 152°C, 161°C, 178°C, 183°C, 194°C, 204°C, 235°C, 252°C, 264°C, 276°C, 280°C, 291°C, 308°C, 313°C, 320°C, 331°C, 337°C, 341°C, 359°C, 361°C, 370°C, 381°C, 391°C, 409°C, 411°C, 420°C, 431°C, 441°C, 459°C, 461°C, 471°C, 481°C, 491°C, 50 The reaction is carried out at a temperature of 84°C, 304°C, 325°C, 338°C, 385°C, 392°C, 400°C, etc.) and a pressure of 5-30 MPa (optionally 5 MPa, 6 MPa, 8 MPa, 9 MPa, 11 MPa, 14 MPa, 16 MPa, 18 MPa, 21 MPa, 22 MPa, 25 MPa, 28 MPa, 30 MPa, etc.) for 1-30 hours to obtain a mixed product containing a solid and a liquid. Preferably, the reaction is carried out at a temperature of 83-97°C and a pressure of 27-30 MPa.

[0049] (5) The mixed product obtained above is subjected to solid-liquid separation to obtain a solid organic modified porous functional material.

[0050] Layered silicate minerals are prepared by calcining coal gangue. These minerals are then directly mixed with soluble silicates and / or soluble silicic acid, metal compounds, organic chelating agents, and water, followed by heating and pressurization to produce a solid organically modified porous functional material. This eliminates the need for acid or alkali treatment, avoiding the problems of impurity dissolution and high acid and alkali consumption associated with acid and alkali treatments. This simplifies the process, allowing the mineral components and metals in the gangue to be synthesized in situ into an organically modified porous functional material in a one-pot process. This material exhibits high specific surface area and a porous structure. The added chelating agent rapidly complexes with metal ions, increasing adsorption performance by dozens of times that of the original gangue. This results in more efficient pollutant removal from wastewater and effective remediation of soils severely contaminated by heavy metals.

[0051] Preferably, the calcination temperature is 195-296°C. Through relatively low-temperature calcination, crystalline aluminum-containing minerals such as kaolinite, the main mineral in the coal gangue, are converted into semi-crystalline or even amorphous minerals such as metakaolinite, whose structure is in a thermodynamically metastable state. The hydroxyl groups (-OH) in the structure are mainly removed, resulting in the breaking of interlayer hydrogen bonds of the layered silicate, loosening the layered structure, and exposing more surface active sites (a large number of broken Si-O and Al-O bonds, forming surface hydroxyl groups (Si-OH, Al-OH) and defect sites, which are conducive to direct reaction and combination with soluble silicates and / or soluble silicic acid, metal compounds, organic complexing agents, etc.), resulting in more amorphous phases (such as amorphous silicon dioxide), which are conducive to subsequent mixing reactions with soluble silicates and / or soluble silicic acid, metal compounds, organic complexing agents, and water. Low temperature calcination overcomes the shortcomings of the original high temperature direct sintering layered structure that cannot be fully transformed into a loose structure and the reaction activity cannot be greatly improved. Low temperature calcination does not completely destroy its layered aluminum silicate skeleton, avoiding the internal pore melting and collapse caused by high temperature calcination, and still maintains a two-dimensional layered structure with an enlarged interlayer spacing, providing insertion channels for soluble silicates and metal ions. Low temperature calcination greatly reduces energy consumption. The main purpose of previous calcination is to remove carbon and activate it. The low temperature calcination of this application is different from its purpose. Through low temperature calcination, it is mainly used to reduce carbon combustion loss, which will be beneficial to carbon retention and the generation of porous carbon such as activated carbon, improving porosity, and making the layered silicate mineral have a fine nano-scale pore structure with rich porous silica and porous carbon (i.e., a pore structure of a silica-C composite structure). At the same time, the layered silicate has a richer Si-O-Al skeleton, which increases the load capacity and load stability, thereby helping to improve adsorption and metal loading capacity. The value of carbon combustion is obviously lower than its value as an adsorption material, which also greatly increases the application value of coal gangue and reduces carbon emissions.

[0052] Soluble silicates (such as sodium silicate, etc.) and / or orthosilicic acid are hydrolyzed to form silicate (SiO4 4- ) or oligomeric silicic acid, by connecting with the active sites of layered silicates, for example, connecting with the Si-O-Al skeleton of layered silicates through a condensation reaction, and the layered open structure of layered silicates can effectively block and separate and insert soluble silicates and / or orthosilicic acid, and silicate ions penetrate into the interlayers, filling the interlayer gaps to form a three-dimensional interpenetrating network, thereby enhancing the mechanical strength of the material. The silicate gel shrinks during the pressurized drying process to produce mesopores (2-30nm) (which are conducive to the diffusion of large molecular pollutants), which together with the mesopores and macropores (>30nm) in the layered silicate mineral structure (reducing mass transfer resistance and providing a stable channel for material migration) form a multi-level pore system, which greatly enriches the pore type and pore density, significantly increases the specific surface area of ​​the material, and improves the adsorption capacity.

[0053] The addition of metal compounds and complexes, such as metal ions (Mg 2+ 、Zn 2+ , Ca 2+ etc.) coordinate with the oxygen atoms of silicates to form a "metal-silicon-oxygen" cross-linked network, which enhances the mechanical strength of the material and is conducive to the stable formation of a small pore structure; and some metal (such as Zn, Ca) oxides have catalytic oxidation ability, which can promote the degradation of organic pollutants; at the same time, the surface of metal oxides is positively charged, which enhances the electrostatic adsorption of anionic pollutants (such as Cr(VI), As(V)). Due to the interlayer anchoring of layered silicate minerals, metal ions can be converted into oxide (such as MgO, ZnO) nanoparticles, whose size is limited by the spatial limitations of the layered structure (usually <10nm), and can exhibit higher catalytic activity; and chelating agents (such as ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, diethyltriacetic acid, nitrilotriacetic acid) chelate metal ions (MgO, ZnO) through carboxylic acid groups. 2+ 、Zn 2+ , Ca 2+ etc.), inhibiting their premature precipitation, ensuring that the metal ions are evenly dispersed in the silicate skeleton, avoiding pore blockage caused by local agglomeration, and thus avoiding pore reduction. The coordination of metal compounds and complexes is conducive to regulating the size of the pores, especially producing a mesoporous structure of appropriate size, thereby improving the reasonable pore distribution and enhancing the adsorption performance.

[0054] Layered silicate minerals are prepared from coal gangue, which are directly mixed with soluble silicates and / or soluble silicic acid, metal compounds, organic chelating agents and water, and then heated and pressurized to react to obtain solid organic modified porous functional materials. This is conducive to the formation of a multi-level pore structure and the increase of carbon pores. No acid or alkali treatment is required, which avoids the problems of impurity dissolution and large acid and alkali consumption in acid and alkali treatment, simplifies the process, and uses a one-pot method to in situ synthesize the mineral components and metals in the coal gangue into organic modified porous functional materials, so that they have characteristics such as high specific surface area and porous structure.

[0055] Wherein, in step (1), the gangue is crushed, sieved, and the powder is subjected to low-temperature calcination. During the process, a 1-3 wt% potassium permanganate aqueous solution (i.e., the mass of potassium permanganate accounts for 1-3 wt%) is sprayed through a nozzle, the sprayed mass accounts for 0.1-0.2 wt% of the mass of the gangue, and the spraying time is 0.5-1 h; the potassium permanganate aqueous solution is used for water treatment and has the function of removing organic pollutants and heavy metal ions; potassium permanganate can decompose oxygen, MnO2, etc. at above 120 degrees Celsius, especially above 150 degrees Celsius. MnO2 has significant advantages in removing pollutants such as organic dyes, heavy metals, antibiotics and phosphorus due to its unique redox activity, high specific surface area, porous structure and rich surface hydroxyl functional groups. The hydroxyl groups (-OH) and oxygen vacancies on the surface of MnO2 can adsorb heavy metal ions (such as Pb 2+ 、Cd 2+ ), MnO2 can reduce Cr(VI) to low-toxic and easily precipitated Cr(III), and oxidize the more toxic As(III) to As(V), which is more easily adsorbed or co-precipitated. The carboxylic acid groups of antibiotic molecules (such as ofloxacin) form hydrogen bonds or coordination bonds with the hydroxyl groups on the surface of MnO2. However, in the existing technology, coal gangue is soaked in potassium permanganate solution, and the decomposition to produce MnO2 is easy to clog the coal gangue pores, affecting the improvement of adsorption performance. MnO2 is easily desorbed during acid and alkali treatment, making it difficult to effectively utilize it; during the low-temperature calcination of coal gangue, oxygen and carbon react slowly, which also affects the formation of carbonaceous micropores. During the low-temperature calcination process of coal gangue powder, a 1-3wt% potassium permanganate aqueous solution is sprayed into the coal gangue, and water reacts with the carbon in the coal gangue to produce water gas, generating hydrogen, CO and associated water vapor, which can effectively improve the circulation of gas in the coal gangue layered structure, facilitate the formation of mesopores with moderate pores, and improve the generation of carbonaceous pores. At the same time, low-content potassium permanganate is sprayed into the coal gangue surface for a long time, decomposes into MnO2 under heat, and accompanies the pore formation process, realizing the loading of MnO2 on the surface and inside of the coal gangue, thereby improving its load dispersion uniformity and loading rate. The generated oxygen reacts with carbon, and reacts with water and carbon in the coal gangue to produce water gas, which is more conducive to the partial consumption of carbon in the coal gangue. The generated gas promotes the formation of pores, which is beneficial to improving the adsorption performance. The concentration and usage of potassium permanganate aqueous solution should not be too high, as this will lead to excessive reaction of carbon, or even complete reaction, and failure to form carbon pores. In addition, the pores are too large, and excessive oxygen generation leads to the risk of explosion. The concentration and usage of potassium permanganate aqueous solution should not be too low, as this will not fully load enough MnO2, and will not be able to effectively and quickly form pores to increase porosity and specific surface area.

[0056] Optionally, in step (1), the gangue is crushed and sieved, and the powder is subjected to high-temperature calcination for 5-10 minutes before being subjected to low-temperature calcination. The calcination temperature is 850-945°C, and microwave-assisted heating is used. The short-term high-temperature calcination is conducive to removing components such as colloidal volatiles (such as hydrocarbons, tar and other organic components) in the gangue, avoiding low-temperature calcination, which causes the retention of colloidal and volatile components and makes it difficult to form pores. The high-temperature short-time treatment can quickly complete the volatilization of the above components and avoid excessive carbon combustion. The rapid escape of volatiles is conducive to the formation of micropores and mesoporous channels inside the gangue, increasing the specific surface area; microwaves are conducive to the loosening and early activation of the mineral phase, causing microcracks inside the mineral, expanding the interlayer spacing, and improving the effect of low-temperature calcination; that is, through high-temperature short-time calcination and auxiliary microwave-assisted heating, pre-pores are formed to prevent the inability to form pores, loosen the mineral phase, increase the interlayer spacing, and then combine with low-temperature calcination (calcination temperature is 195-296℃), which is more conducive to the optimization of the pore-forming process to form a suitable multi-level pore structure of coal gangue.

[0057] It can be understood that the calcination can be carried out by flash furnace calcination, stirring heating calcination, heating ball mill calcination, etc., so as to make the calcination process uniform, and the potassium permanganate solution can be sprayed uniformly.

[0058] Optionally, the kaolinite content in the layered silicate mineral obtained after calcining the gangue is not less than 40%. By controlling the kaolinite content in the layered silicate mineral obtained after calcining the gangue at a high level, excessive calcination is avoided, thereby avoiding the destruction of the layered structure of the gangue and the impact on the formation of an open, loose, active aluminosilicate network. After calcination, the gangue is dehydroxylated and converted into metakaolinite. Its unique layered structure has significant advantages in pore formation, increased specific surface area, and optimized material properties.

[0059] Optionally, the powder particle size of the crushed gangue is between 48 and 200 μm (optionally 48 μm, 53 μm, 57 μm, 64 μm, 69 μm, 78 μm, 82 μm, 91 μm, 101 μm, 113 μm, 124 μm, 135 μm, 142 μm, 156 μm, 167 μm, 178 μm, 182 μm, 195 μm, 200 μm, etc.). Preferably, the particle size is between 48 and 85 μm. This shortens the mass transfer distance within the fine particles, allowing for more rapid escape of residual organic volatiles (such as tar and hydrocarbons) during calcination. Furthermore, kaolinite and other layered silicates undergo more thorough dehydroxylation within the fine particles, transforming them into the active structure of metakaolinite, which facilitates the formation of uniformly distributed micropores and mesopores.

[0060] Optionally, the soluble silicate is one or any combination of lithium silicate, sodium silicate, ammonium silicate, and potassium silicate; the soluble silicic acid is orthosilicic acid; and the added amount is such that the mass ratio of gangue to soluble silicate and / or soluble silicic acid is 1:(4.5-5.5) (optionally 1:4.5, 1:4.6, 1:4.7, 1:4.8, 1:4.9, 1:5, 1:5.1, 1:5.2, 1:5.3, 1:5.4, 1:5.5, etc.). Controlling the amount of soluble silicate added facilitates the formation of pores of appropriate size through polycondensation. Too much soluble silicate intercalates and coats the layered silicate, affecting the formation of a multi-level pore system. Too little soluble silicate fills a small amount of voids, hindering the formation of a three-dimensional interpenetrating network and enhancing the mechanical strength of the material while also increasing the pore size. Both too high and too low a soluble silicate addition are detrimental to improving adsorption performance.

[0061] Optionally: the soluble silicates are lithium silicate, sodium silicate, and potassium silicate, and based on the total mass of the soluble silicates, the ratio of lithium silicate: sodium silicate: potassium silicate is 1:(12-13):(13-14); sodium silicate is hydrolyzed to form silicate ions, the gelation process of which is highly controllable and easy to control to form a mesoporous structure; the potassium ion has a larger ionic radius, which is beneficial to delaying the condensation rate and expanding the pore size distribution (mesopores and macropores coexist), and the strong polarization effect of lithium ions promotes the densification of the silicate gel structure, thereby facilitating the improvement of pore strength and the maintenance of pore stability; the sodium, potassium, and lithium trication system can balance the gelation rate with structural stability and pore radius, thereby improving adsorption performance.

[0062] Optionally, the metal compound is one or any combination of magnesium chloride, magnesium oxide, basic magnesium carbonate, zinc chloride, zinc sulfate, zinc nitrate, zinc dihydrogen phosphate, calcium oxide, calcium chloride, magnesium sulfate, magnesium nitrate, magnesium acetate, calcium halide, calcium carbonate, calcium nitrate, calcium chlorate, and calcium perchlorate, and is added in an amount such that the mass ratio of gangue to the metal compound is 1:2.5-3.5 (optionally 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3, 1:3.1, 1:3.2, 1:3.3, 1:3.4, 1:3.5, etc.). An appropriate amount of metal compound added facilitates the stable formation of a small pore structure and high catalytic ability. Too high or too low a ratio is detrimental to the formation of a pore structure, especially micropores.

[0063] Preferably, the metal compound is magnesium oxide, zinc chloride and calcium oxide, and based on the total mass of the metal compound, the ratio of magnesium oxide: zinc chloride: calcium oxide is 1: (0.2-0.3): (1.3-1.5); the MgO surface site (O 2- ) complements the MnO2 site (Mn-OH) to synergistically adsorb anionic pollutants (such as Cr(VI)); zinc chloride can enhance the decomposition of tetracycline and other substances under visible light; after CaO and MnO2 are combined, SO4 in wastewater can be fixed. 2- PO43- , reducing the competitive adsorption of MnO2 active sites and simultaneously improving the absorption of heavy metals (such as Cd 2+ ) removal rate. By selecting the appropriate ratio of the above metal compounds, it is beneficial to improve the removal efficiency of heavy metal ions and the decomposition efficiency of tetracycline.

[0064] Optionally, the amount of deionized water added is such that the mass ratio of gangue to deionized water is 1:35-45 (optionally 1:35, 1:36, 1:37, 1:38, 1:39, 1:40, 1:41, 1:42, 1:43, 1:44, 1:45, etc.).

[0065] Optionally, the complexing agent is one or any combination of nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and diethyltriacetic acid, with a mass concentration of 0.1-30% (optionally 0.1%, 0.6%, 1.8%, 3.3%, 5.4%, 6.8%, 9.1%, 11%, 15%, 17%, 19%, 21%, 23%, 25%, 27%, 28%, 29%, 30%, etc.), preferably 1.1-5.3%.

[0066] Preferably: the complexing agent is ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, and the ratio of ethylenediaminetetraacetic acid to diethylenetriaminepentaacetic acid is 1:(0.3-0.4) based on the total mass of the complexing agent; ethylenediaminetetraacetic acid has four carboxylic acid groups and two amino groups, and has strong chelating ability, which is conducive to forming a stable coordination complex with metal ions. The strong chelating effect can inhibit the premature precipitation of metal ions, ensure the uniform dispersion of metal ions in the precursor solution, thereby forming a uniform pore structure during the subsequent heating process, delaying the condensation rate of silicates or metal oxides, and promoting the formation of hierarchical pores (micropores-mesopores); diethylenetriaminepentaacetic acid has eight coordination atoms (three amino groups and five carboxylic acid groups), and its chelating ability for transition metal Mn ions is greater than that of ethylenediaminetetraacetic acid, which can stabilize the active sites on the surface of MnO2 and promote its catalytic effect. The long chain structure of diethylenetriaminepentaacetic acid can shield anions in water (such as Cl - 、SO4 2- ) competitive adsorption on MnO2 active sites, maintaining efficient removal capabilities in complex water conditions. By properly controlling the ratio, the catalytic effect of manganese dioxide is promoted, while also promoting the formation of hierarchical pores, which is beneficial for improving adsorption.

[0067] Optionally, the pH value of the suspension A is 5-12 (optionally 5, 6, 7, 8, 9, 10, 11, 12, etc.), and an alkaline metal compound may be added to adjust the pH.

[0068] Example 1

[0069] A method for in-situ synthesis of organically modified porous functional materials using coal gangue, comprising:

[0070] (1) The gangue is crushed to obtain a powder with an average particle size of 84 μm, and the powder is sieved. Before the powder is subjected to low-temperature calcination, it is subjected to high-temperature calcination for 6 minutes at a calcination temperature of 873°C, microwave-assisted heating, and then the powder is calcined at 211°C for 6 hours to obtain a layered silicate mineral; the kaolinite content in the layered silicate mineral obtained after the calcination of the gangue is not less than 70%; wherein, in step (1), the gangue is crushed, sieved, and the powder is subjected to low-temperature calcination, and a 2wt% potassium permanganate aqueous solution is sprayed through a nozzle, the sprayed mass accounts for 0.2wt% of the mass of the gangue, and the spraying time is 0.5 hour.

[0071] (2) 2.1 g of layered silicate mineral, 10.7 g of soluble silicate, 6.8 g of metal compound, and 91 ml of deionized water were mixed, stirred, and then ultrasonically treated with a cell crusher to obtain a suspension A. The soluble silicate was lithium silicate, sodium silicate, and potassium silicate. The ratio of lithium silicate to sodium silicate to potassium silicate was 1:12:14 based on the total mass of the soluble silicate. The metal compound was magnesium oxide, zinc chloride, and calcium oxide. The ratio of magnesium oxide to zinc chloride to calcium oxide was 1:0.2:1.4 based on the total mass of the metal compound.

[0072] (3) 0.12 g of a complexing agent was added to suspension A, followed by stirring to obtain a uniform precursor solution; the mass concentration of the complexing agent was 3.1%. The complexing agents were ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, and the ratio of ethylenediaminetetraacetic acid to diethylenetriaminepentaacetic acid, based on the total mass of the complexing agent, was 1:0.3.

[0073] (4) The precursor solution obtained above was transferred into a closed reactor and reacted at 84°C and 28 MPa for 5 h to obtain a mixed product containing solid and liquid.

[0074] (5) The mixed product obtained above is subjected to solid-liquid separation to obtain a solid organic modified porous functional material. Figure 1-5 As shown in Table 1-2, the organic modified porous functional material prepared in Example 1 has a small pore size, a large specific surface area, a high pore volume, and a nanocluster structure, and has good adsorption properties for organic dyes, heavy metals, tetracycline hydrochloride and phosphorus. Figure 4 This is the pore size distribution curve of the organically modified porous functional material of Example 1, where the ordinate is dV / dlogD, representing the pore volume change (dV) within the unit logarithmic pore size interval (dlogD), in cm³ / g; the abscissa is the pore diameter, in nm.

[0075] Table 1 Pore structure parameters of organically modified porous functional materials

[0076]

[0077] Table 2 Adsorption properties of organic modified porous functional materials for organic dyes, heavy metals, tetracycline hydrochloride, and phosphorus

[0078]

[0079] Example 2

[0080] The method is basically the same as that of Example 1, except that in step (1), the gangue is crushed and sieved, and the powder is calcined at a temperature of 793° C. Compared with Example 1, the high calcination temperature is not conducive to improving the adsorption performance.

[0081] Example 3

[0082] The method is basically the same as that of Example 1, except that: in step (1), the gangue is crushed and sieved, and the powder is subjected to low-temperature calcination before high-temperature calcination and microwave-assisted heating are not performed.

[0083] Example 4

[0084] The method is basically the same as that in Example 1, except that the average particle size of the powder after the coal gangue is crushed is 195 μm.

[0085] Example 5

[0086] The method is basically the same as that of Example 1, except that: 2.1 g of layered silicate mineral, 8.4 g of soluble silicate, and 8 g of metal compound.

[0087] Example 6

[0088] The method is basically the same as that of Example 1, except that the soluble silicate is lithium silicate.

[0089] Example 7

[0090] The method is basically the same as that in Example 1, except that the metal compound is zinc chloride.

[0091] Example 8

[0092] The method is basically the same as that in Example 1, except that the complexing agent is ethylenediaminetetraacetic acid.

[0093] Example 9

[0094] The method is basically the same as that of Example 1, except that the reaction is carried out at a temperature of 312° C. and a pressure of 30 MPa to obtain a mixed product containing solid and liquid.

[0095] Comparative Example 1

[0096] The method is basically the same as that of Example 1, except that: in step (1), the coal gangue is crushed and sieved, and the powder is subjected to low-temperature calcination without spraying the potassium permanganate aqueous solution through the nozzle.

[0097] Comparative Example 2

[0098] The method is basically the same as that of Example 1, except that the powder is calcined at 1300° C. for 2 h.

[0099] Comparative Example 3

[0100] The method is basically the same as that of Example 1, except that the precursor solution obtained above is transferred into a closed reactor and reacted at a temperature of 500° C. and a pressure of 5-30 MPa.

[0101] Comparative Example 4

[0102] The method is basically the same as that of Example 1, except that no complexing agent is added.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for in-situ synthesis of organic modified porous functional materials using coal gangue, characterized in that: include: (1) Grinding and sieving the coal gangue, and calcining the powder at 195-296°C for 2-24 hours to obtain layered silicate minerals; (2) 1-10 g of layered silicate mineral, 5-50 g of soluble silicate and / or soluble silicic acid, 3-30 g of metal compound and 40-400 ml of deionized water are mixed, stirred, and then subjected to ultrasonic treatment in a cell crusher to obtain a suspension A; the soluble silicic acid is orthosilicic acid; the metal compound is one or any combination of magnesium chloride, magnesium oxide, basic magnesium carbonate, zinc chloride, zinc sulfate, zinc nitrate, zinc dihydrogen phosphate, calcium oxide, magnesium sulfate, magnesium nitrate, magnesium acetate, calcium halide, calcium carbonate, calcium nitrate, calcium chlorate, and calcium perchlorate, and the added amount is such that the mass ratio of coal gangue to the metal compound is 1:2.5-3.5; (3) adding 0.05-5 g of a complexing agent to the suspension A, followed by stirring to obtain a uniform precursor solution; the complexing agent is one or any combination of nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and diethyltriacetic acid, with a mass concentration of 0.1-30%; (4) The precursor solution obtained above is transferred into a closed reactor and reacted at a temperature of 50-400°C and a pressure of 5-30 MPa for 1-30 hours to obtain a mixed product containing solid and liquid; (5) performing solid-liquid separation on the mixed product obtained above to obtain a solid organic modified porous functional material; In step (1), the gangue is crushed and sieved, and during the low-temperature calcination of the powder, a 1-3 wt% potassium permanganate aqueous solution is sprayed through a nozzle, the sprayed mass accounts for 0.1-0.2 wt% of the mass of the gangue, and the spraying time is 0.5-1 h; the calcination temperature of the low-temperature calcination is 195-296 ° C.

2. The method for in-situ synthesis of organically modified porous functional materials using coal gangue according to claim 1, characterized in that: In step (1), the gangue is crushed and sieved, and the powder is calcined at high temperature for 5-10 minutes before being calcined at low temperature. The calcination temperature is 850-945°C, and microwave-assisted heating is used.

3. The method for in-situ synthesis of organically modified porous functional materials using coal gangue according to claim 1, characterized in that: The kaolinite content in the layered silicate minerals obtained after calcining the coal gangue is not less than 40%; the particle size of the powder after the coal gangue is crushed is 48-200μm.

4. The method for in-situ synthesis of organically modified porous functional materials using coal gangue according to claim 1, characterized in that: The soluble silicate is one or any combination of lithium silicate, sodium silicate, ammonium silicate, and potassium silicate, and the added amount is such that the mass ratio of coal gangue to soluble silicate and / or soluble silicic acid is 1:(4.5-5.5).

5. The method for in-situ synthesis of organically modified porous functional materials using coal gangue according to claim 4, characterized in that: The soluble silicates are lithium silicate, sodium silicate and potassium silicate. Based on the total mass of the soluble silicates, the ratio of lithium silicate: sodium silicate: potassium silicate is 1: (12-13): (13-14).

6. The method for in-situ synthesis of organically modified porous functional materials using coal gangue according to claim 4, characterized in that: The metal compound is magnesium oxide, zinc chloride and calcium oxide. Based on the total mass of the metal compound, the ratio of magnesium oxide: zinc chloride: calcium oxide is 1: (0.2-0.3): (1.3-1.5).

7. The method for in-situ synthesis of organically modified porous functional materials using coal gangue according to claim 4, characterized in that: The complexing agent is ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid. Based on the total mass of the complexing agent, the ratio of ethylenediaminetetraacetic acid to diethylenetriaminepentaacetic acid is 1:(0.3-0.4).

8. The method for in-situ synthesis of organically modified porous functional materials using coal gangue according to claim 1, characterized in that: The amount of deionized water added is such that the mass ratio of gangue to deionized water is 1:35-45.

9. The method for in-situ synthesis of organically modified porous functional materials using coal gangue according to claim 1, characterized in that: The pH value of the suspension A is between 5 and 12, and an alkaline metal compound is added to adjust the pH value.

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