Coal gasification slag-based adsorbent material, and preparation method and application thereof

Abstract

This invention belongs to the field of adsorbent preparation, and relates to an adsorbent material based on coal gasification slag, its preparation method, and its applications. The method includes: (S1) calcining coal gasification slag under an inert atmosphere to obtain a porous carbon material; (S2) dissolving titanate and carboxylate in an organic solvent to obtain a mixed organic solution; (S3) adding the porous carbon material to the mixed organic solution for modification treatment to obtain a modified porous carbon material; (S4) reacting the modified porous carbon material with a coating agent to obtain a mixed reaction mixture; (S5) reacting and coating a silicon source reagent, a silane coupling agent, and the mixed reaction mixture, followed by solid-liquid separation, and then sequentially washing, drying, and granulating the resulting silica sol-coated modified porous carbon material to obtain a first adsorbent material. This invention uses coal gasification slag as raw material, and through inert calcination, titanate-carboxylate composite modification, and silica sol coating, achieves high-value utilization of coal gasification slag and improves the adsorption performance and stability of the adsorbent material.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization and wastewater treatment technology. Specifically, it relates to an adsorption material based on coal gasification slag, its preparation method, and its application. Background Technology

[0002] Water scarcity is a key constraint on socio-economic development and ecological environmental protection, especially in arid and semi-arid regions worldwide. The efficient treatment and resource recycling of various industrial wastewater and sewage have become core needs for alleviating water resource pressure and practicing environmental protection concepts.

[0003] Meanwhile, the coal chemical industry generates a large amount of coal gasification slag during production. Currently, this type of solid waste is mostly disposed of through landfill or dumping, which not only occupies significant land resources but also easily generates dust pollution. Its disposal has become a major burden on enterprises' sustainable development and environmental governance. It is worth noting that coal gasification slag itself possesses characteristics such as large specific surface area, high porosity, and high carbon content, and has been proven to have the potential to adsorb pollutants from water bodies, providing an important foundation for its resource utilization.

[0004] However, existing adsorption materials based on coal gasification slag still have many shortcomings: First, the material structure has low strength, making it easy to break and lose during water treatment, resulting in a short service life; second, the active components are not firmly loaded, making them easy to fall off during regeneration, resulting in poor recycling performance; third, the treatment efficiency for high-salt and complex wastewater is low, and the anti-pollution ability is weak, making it difficult to meet the treatment needs of typical industrial wastewater such as clean water from coal-fired power plants; fourth, some preparation processes are complex and costly, limiting their large-scale application.

[0005] Therefore, developing an adsorption material based on coal gasification slag that is structurally stable, has good circulation performance, and is highly efficient in treating high-salt wastewater is of great practical significance. Summary of the Invention

[0006] The purpose of this invention is to provide an adsorption material based on coal gasification slag, its preparation method and application, in order to solve the problems of poor structural stability, poor recycling performance and low efficiency in treating high-salt and complex wastewater of existing coal gasification slag-based adsorption materials.

[0007] Based on the above considerations, the first aspect of the present invention provides a method for preparing adsorbent materials using coal gasification slag, the method comprising the following steps: (S1) The coal gasification slag is calcined under an inert atmosphere to obtain porous carbon material; (S2) Dissolve the titanate and carboxylate in an organic solvent to obtain a mixed organic solution; (S3) The porous carbon material is added to the mixed organic solution for modification treatment to obtain modified porous carbon material; (S4) The modified porous carbon material is mixed with a coating agent and subjected to a mixing reaction to obtain a mixed reaction material; (S5) The silicon source reagent, silane coupling agent and the mixed reactant are mixed and reacted and coated. After the reaction is completed, solid-liquid separation is performed, and the modified porous carbon material coated with the obtained silica sol is washed, dried and granulated in sequence to obtain the first adsorbent material. Optionally (S6), the first adsorbent material, functional monomer, comonomer and mixed solvent are uniformly mixed, and an initiator is added to carry out the reaction; after the reaction is completed, solid-liquid separation is performed and the resulting product is washed, dried and granulated in sequence to obtain the second adsorbent material.

[0008] A second aspect of the present invention provides an adsorbent material obtained by the above method, wherein, The adsorbent material has a particle size of 1-5 mm, a moisture content of ≤5%, and a specific surface area of ​​300-800 m². 2 / g, with a porosity of 40%~70%.

[0009] A third aspect of the present invention provides an application of the above-mentioned adsorbent material for treating wastewater from coal-fired power plants; wherein, The TDS content of the clean wastewater from the coal-fired power plant is 3000~4000 mg / L, of which Na + The content is 2500~3200 mg / L, Ca 2+ The content is 350~450 mg / L, Cl - The content is 3000~3600 mg / L; Preferably, the process conditions are as follows: adsorption temperature 20~40℃, pH 5~9, volume ratio of clean wastewater from coal-fired power plants to adsorption material of (50~200):1, and adsorption time 0.5~2 h.

[0010] Beneficial effects 1. This invention uses coal gasification slag as raw material and achieves high-value utilization of coal gasification slag through a stepwise preparation process of inert calcination, titanium ester-carboxylate composite modification, and silica sol coating. At the same time, it significantly improves the basic adsorption performance and structural stability of the adsorption material.

[0011] 2. This invention involves high-temperature calcination of coal gasification slag in an inert atmosphere, which transforms the residual carbon in the coal gasification slag into a porous carbon skeleton with a certain degree of graphitization. At the same time, volatile impurities are removed, and a carbon matrix with high specific surface area and interconnected pores is constructed, providing a high-quality carrier for subsequent loading of active ingredients.

[0012] 3. The present invention modifies the porous carbon matrix with titanate-carboxylate composite treatment, thereby generating a uniform TiO2 modified layer in situ on the surface of the porous carbon material, increasing the chemical adsorption sites of the material and improving its adsorption capacity for pollutants such as heavy metal ions.

[0013] 4. This invention performs silica sol coating treatment on TiO2 modified porous carbon to form an ultrathin porous silica sol layer on the material surface, which not only protects the internal pore structure from damage, but also improves the mechanical strength and water resistance of the material, while providing a stable interface for subsequent functionalization modification.

[0014] 5. In this invention, the silica sol coating material is optionally subjected to mercapto-initiated zwitterionic-acrylamide graft polymerization treatment to form a polymer hydrogel functional layer in situ on the silica sol surface, which significantly improves the material's treatment efficiency and anti-pollution performance for high-salt wastewater and broadens the application range of the material.

[0015] 6. The adsorbent material prepared by this invention has good recycling performance and can be reused through simple acid washing and elution, which greatly reduces the cost of water treatment and is suitable for the treatment of various industrial wastewaters such as clean water from coal-fired power plants. Detailed Implementation

[0016] The technical solution and its effects of the present invention will be further described below with reference to specific embodiments / examples. The following embodiments / examples are merely illustrative of the present invention and are not intended to limit it. Simple modifications made to the present invention based on the concept of the present invention are all within the scope of protection claimed by the present invention.

[0017] The method for preparing adsorbent materials using coal gasification slag provided in the first aspect of the present invention includes the following steps: (S1) The coal gasification slag is calcined under an inert atmosphere to obtain porous carbon material; (S2) Dissolve the titanate and carboxylate in an organic solvent to obtain a mixed organic solution; (S3) The porous carbon material is added to the mixed organic solution for modification treatment to obtain modified porous carbon material; (S4) The modified porous carbon material is mixed with a coating agent and subjected to a mixing reaction to obtain a mixed reaction material; (S5) The silicon source reagent, silane coupling agent and the mixed reactant are mixed and reacted and coated. After the reaction is completed, solid-liquid separation is performed, and the modified porous carbon material coated with the obtained silica sol is washed, dried and granulated in sequence to obtain the first adsorbent material. Optionally (S6), the first adsorbent material, functional monomer, comonomer and mixed solvent are uniformly mixed, and an initiator is added to carry out the reaction; after the reaction is completed, solid-liquid separation is performed and the obtained product is washed, dried and granulated in sequence to obtain the second adsorbent material.

[0018] Step (S1): Preparation of porous carbon materials In this invention, step (S1) mainly involves high-temperature calcination in an inert atmosphere to transform the residual carbon in the coal gasification slag into a porous carbon framework with a certain degree of graphitization. Simultaneously, volatile impurities are removed, constructing a carbon matrix with high specific surface area, interconnected pores, and uniform distribution. This provides a structurally stable core carrier with sufficient adsorption sites for subsequent loading of active ingredients and functionalization modification. In some embodiments, the porous carbon material obtained in step (S1) can be washed and dried to further optimize the carbon matrix properties.

[0019] In some embodiments, in step (S1), the coal gasification slag refers to the molten slag formed by the high-temperature conversion of the remaining inorganic matter after coal reacts with an oxidant (oxygen or water vapor) in a reactor to generate gas. Depending on its discharge location in the gasifier, it can be selected as coarse coal gasification slag, fine coal gasification slag, or a mixture of both.

[0020] In some embodiments, the coarse coal gasification slag is formed by the condensation and solidification of minerals in coal after they are converted into molten slag, accounting for 60-80% of the total amount of coal gasification slag. After calcination, the coarse coal gasification slag can form a carbon-inorganic composite framework, which has both good adsorption performance and mechanical strength, and is suitable as a basic carrier for adsorption materials.

[0021] The key parameters of the coal gasification coarse slag include: a fixed carbon content of 15-40 wt%, which serves as the core carbon source and determines the proportion of porous carbon skeleton and basic adsorption performance after calcination; an ash content of 50-75 wt%, with SiO2 and Al2O3 as the main components, forming a natural inorganic reinforcing phase that significantly improves the mechanical strength of the material; a median particle size of 100-500 μm, with relatively large particles that are not prone to agglomeration, facilitating subsequent solid-liquid separation and granulation operations; an initial porosity of 20-40%, possessing a preliminary pore structure that can further develop into hierarchical channels after calcination and activation; and a water leaching solution with a pH of 7.0-9.0, which is weakly alkaline and can be directly used for calcination and subsequent modification reactions without additional adjustment.

[0022] In some embodiments, the coal gasification fine slag is a small-particle molten slag that is cooled by the airflow and discharged in the form of a filter cake, appearing as fly ash. After being treated by the inert calcination process of the present invention, it can effectively unclog blocked channels and generate a large number of new pores, significantly improving the adsorption potential.

[0023] The key parameters of the coal gasification fine slag include: a fixed carbon content of 10-50 wt%, which can be adjusted by modifying the calcination process to obtain carbon matrices with different specific surface areas; an ash content of 40-80 wt%, containing small amounts of alkali metal oxides such as K2O and Na2O, which can act as natural activators to promote pore formation during calcination; a median particle size of 10-100 μm, with fine particles and a large potential for specific surface area, but prone to agglomeration, requiring thorough dispersion in step (S4); and an initial specific surface area of ​​0.5-80 m². 2 / g: The pores are mostly blocked by residual coal tar, which can be increased to 300~800 m after inert calcination according to this invention. 2 / g; moisture content 8~18% (50~70% for filter cake), pre-drying treatment is required to avoid material agglomeration during calcination.

[0024] In some embodiments, in step (S1), the inert atmosphere is selected from nitrogen, argon, or other conventional inert gases. Its core functions are twofold: first, to isolate the carbon from air (oxygen), preventing the residual carbon in the coal gasification slag from being oxidized and burned, thus ensuring the complete preservation of the carbon skeleton; second, in an oxygen-free environment, volatile gases (such as CO, CH4, etc.) generated by the pyrolysis of residual carbon will escape from the interior of the carbon matrix, thereby etching out a large number of new micropores and mesopores, significantly increasing pore volume and specific surface area. If calcination is carried out in an air atmosphere, a large amount of residual carbon will be burned and consumed, which is not conducive to the formation of a continuous carbon skeleton and will also cause the original pores to collapse, completely losing the function of the adsorption carrier.

[0025] In some embodiments, in step (S1), the calcination reaction temperature is 800~1000 ℃. This temperature range is beneficial for fully removing residual coal tar, moisture, and other volatile impurities from the coal gasification slag, for transforming residual carbon into a moderately graphitized structure, forming a porous carbon skeleton with stable structure and excellent mechanical properties, and for clearing existing blocked pores and generating a large number of new pores in situ, thereby obtaining a specific surface area of ​​300~800 m². 2 A highly active carbon matrix with a porosity of 40%~70% per gram enhances the uniformity of loading and the strong binding of subsequent active components.

[0026] Preferably, the calcination reaction time is 2-4 h. This range is conducive to the full removal of volatile impurities, the moderate degree of graphitization of residual carbon, and the full development of the pore structure. It is also conducive to improving the economy and stability of the preparation process while ensuring the adsorption performance of the carbon matrix.

[0027] In some embodiments, step (S1) may also include washing the calcined product. The washing may be performed in one of the following two ways: one is to wash directly with distilled water until the filtrate is neutral; the other is to wash first with dilute hydrochloric acid with a concentration of 1-3 wt%, and then rinse with distilled water until the filtrate is neutral. This is beneficial for fully dissolving residual calcium, magnesium and other metal oxides and improving the stability of subsequent processing.

[0028] In some embodiments, step (S1) may further include drying the washed product at a temperature of 60-80 °C for 2-3 h. This combination of temperature and time is beneficial for rapidly removing moisture after washing, maintaining the integrity of the pore structure of the porous carbon material, and preserving a high-quality porous structure.

[0029] Preferably, the moisture content of the dried porous carbon material is ≤5%, which is more conducive to the uniform mixing with the organic solution in step (S2), avoids agglomeration, and ensures the uniformity and effectiveness of the modification treatment.

[0030] Step (S2): Preparation of the titanate-carboxylate composite active system In this invention, step (S2) is to prepare a titanate-carboxylate composite active system for modifying porous carbon materials. The carboxylate acts as a chelating agent and structure directing agent, and regulates its hydrolysis and polycondensation rate through coordination with the titanate. This lays the foundation for the subsequent in-situ generation of a uniform and stable TiO2 modified layer on the porous carbon surface, ensuring that the modification effect is uniform and controllable.

[0031] In some embodiments, in step (S2), the titanate is selected from at least one of tetraisopropyl titanate, tetrabutyl titanate, trifluoroacetyl titanate, chloroisopropyl tris(dioctylphosphoyloxy) titanate, isopropyl tris(stearoyl) titanate, di(dioctylpyrophosphoyloxy)oxoacetate titanate, di(dioctyl phosphite)tetraisopropyl titanate, or other conventional titanate compounds.

[0032] Preferably, the titanate is selected from at least one of tetraisopropyl titanate, tetrabutyl titanate, and trifluoroacetyl titanate; wherein, tetraisopropyl titanate and tetrabutyl titanate have moderate reactivity, which is more conducive to forming stable coordination compounds with carboxylates, and their hydrolysis products can firmly bind to the hydroxyl groups on the porous carbon surface, significantly improving the loading stability of the active ingredient; special titanates such as trifluoroacetyl titanate can introduce functional groups, which is more conducive to enhancing the adsorption selectivity of the adsorbent material for specific pollutants.

[0033] In some embodiments, in step (S2), the carboxylate is selected from at least one of sodium tartrate, sodium oxalate, sodium malate, sodium citrate dihydrate, and sodium salicylate, or other carboxylate with a multi-carboxyl structure. These carboxylates all have good organic solvent solubility, and the multiple carboxyl groups in the molecule can act as chelating sites to form stable coordination bonds with the titanium ions of the titanate. On the one hand, this is beneficial for controlling the hydrolysis and polycondensation rate of the titanate and inhibiting the aggregation of TiO2 nanoparticles; on the other hand, it is beneficial for guiding the uniform growth of TiO2 on the porous carbon surface. At the same time, the carboxyl groups themselves can provide additional adsorption sites, which is beneficial for enhancing the adsorption capacity of the adsorption material.

[0034] Preferably, the mass ratio of the titanate to the carboxylate is 1:(1~5). This ratio is more conducive to the full coordination and chelation of the titanate and the carboxylate to form a structurally stable active precursor complex. This is beneficial for the precise control of the hydrolysis and polycondensation process of the titanate, and at the same time, it helps to reduce the excessive residue of carboxylate and ensure the unobstructed pores of the porous carbon material.

[0035] In some embodiments, in step (S2), the organic solvent is selected from at least one of petroleum ether, diethyl ether, ethyl acetate and N,N-dimethylformamide, or other organic solvents well known in the art.

[0036] Ethyl acetate and N,N-dimethylformamide have strong solubility for titanates and carboxylates, which is more conducive to forming a homogeneous solution system. They also have moderate boiling points (e.g., ethyl acetate has a boiling point of about 75~80 ℃, and N,N-dimethylformamide has a boiling point of about 150~155 ℃), which is beneficial for subsequent temperature control to control the solvent evaporation rate and improve preparation efficiency. Petroleum ether and diethyl ether are suitable for scenarios that require low-boiling-point solvents and are more conducive to shortening the solvent evaporation time.

[0037] Preferably, the amount of organic solvent added is 5 to 20 times the total mass of titanate and carboxylate, which is beneficial to balance uniform dispersion and economical preparation.

[0038] In some embodiments, in step (S2), the dissolution process can be carried out by magnetic stirring or mechanical stirring at a stirring rate of 100-200 r / min for a stirring time of 15-30 min. This operation is conducive to the full contact and uniform mixing of the components, ensuring the stability of the active system.

[0039] Preferably, ultrasonic treatment can be used as an adjunct during the dissolution process, with an ultrasonic power of 200-300 W and an ultrasonic time of 10-20 min. Ultrasonic vibration is more conducive to breaking up any small agglomerates that may exist in the titanate, further improving the dispersion uniformity of the mixed organic solution, ensuring the uniform loading of the active ingredients on the surface of the porous carbon material, and significantly improving the overall effect of the modification treatment.

[0040] Step (S3): Modification treatment of porous carbon materials In this invention, step (S3) involves the hydrolysis and polycondensation reaction of titanate to obtain a uniform titanium oxide (TiO2) modified layer in situ on the surface and pores of the porous carbon material in step (S2). During this process, the carboxylate continues to play a chelating and regulating role or acts as a structure directing agent to promote the uniform dispersion of titanate and its combination with the carbon matrix, thereby achieving the initial modification of the porous carbon material.

[0041] In some embodiments, in step (S3), the mass ratio of the porous carbon material to the total mass of titanate and carboxylate in the mixed organic solution is 1:(0.08~0.25). This ratio is beneficial for the uniform growth of the TiO2 modified layer on the inner and outer surfaces of the porous carbon, ensuring sufficient adsorption sites, while preventing excessive accumulation of TiO2 particles that clog pores, thus balancing modification effectiveness and economic efficiency, and is unaffected by fluctuations in the amount of organic solvent used. In other embodiments, the mass-to-volume ratio of the porous carbon material to the mixed organic solution is 1 g:(200~600) mL.

[0042] In some embodiments, in step (S3), the temperature of the modification treatment is 60~80°C. This temperature range is conducive to accelerating the evaporation rate of organic solvents, promoting the stable hydrolysis and polycondensation of titanate, and facilitating the uniform nucleation and growth of TiO2 nanoparticles, thus ensuring the continuity and uniformity of the TiO2 modified layer.

[0043] Preferably, the modification treatment time can be 1 to 3 hours, during which the organic solvent in the porous carbon material is removed by evaporation. This duration is conducive to the full formation of the TiO2 modified layer and its firm bonding with the carbon matrix, which helps to ensure the stability and consistency of the subsequent reaction system.

[0044] Preferably, the modification process involves continuous stirring at a rate of 150-300 r / min. This rate facilitates the uniform dispersion of porous carbon particles, promotes full contact between the active precursor and the carbon surface, further enhances the uniformity of the TiO2 modified layer load, and ensures the stability of the modification effect.

[0045] Preferably, after the modification treatment, the reaction product is dried (e.g., at a temperature of 50-60 °C for 1-2 hours), which helps to remove any trace amounts of solvent that may remain and facilitates the formation of a structurally stable and uniformly dispersed TiO2-carboxylate composite modified layer. This modified layer can efficiently adsorb pollutants such as heavy metal ions and chloride ions in water through electrostatic and coordination interactions, significantly improving the initial adsorption performance of the material.

[0046] Step (S4): Mixing and reacting porous carbon materials with coating agents In this invention, step (S4) involves surface modification and dispersion control of the TiO2-modified porous carbon (i.e., the modified porous carbon material) obtained in step (S3) using a coating agent. This improves the wettability of the material surface, enhances the dispersion stability of the system, and provides uniform anchoring points and structural guidance for subsequent silica sol coating. This ensures the uniformity and bonding strength of the silica sol coating layer, laying the foundation for final functional modification.

[0047] In some embodiments, in step (S4), the coating agent is selected from at least one of polyvinylpyrrolidone (PVP), polyethylene glycol (PEG, for example, molecular weight 1000~2000), low molecular weight polyacrylamide (PAM, for example, molecular weight ≤10000), hydroxypropyl methylcellulose (HPMC), and polyethylene oxide (PEO, for example, molecular weight 10000~30000).

[0048] These polymeric coating agents all possess excellent adsorption and film-forming properties as well as steric hindrance effects, which are beneficial for reducing particle agglomeration. They can also act as interface modifiers to adjust the surface properties of materials, adapting to the subsequent silica sol coating requirements. Furthermore, they are chemically stable, exhibiting no adverse reactions with the modified porous carbon materials, and possess good water or alcohol solubility, making them suitable for the solvent system of this solution. Specifically, polyethylene glycol performs excellently in the dispersion of ultrafine powders, which is beneficial for optimizing the uniformity of particle size distribution; hydroxypropyl methylcellulose facilitates the formation of a regular and loose particle dispersion system with outstanding dispersion stability; low molecular weight polyacrylamide can improve the viscous stability of the system and assist in dispersion; and polyethylene oxide inhibits agglomeration through the steric hindrance of its molecular chains, adapting to the dispersion requirements of multiphase systems.

[0049] Preferably, the coating agent is polyvinylpyrrolidone, which has superior overall performance and the following core advantages: First, as a structure-directing agent and stabilizer, it can precisely control the nucleation and growth process of silica sol particles by forming hydrogen bonds with the tetraethyl orthosilicate hydrolysis intermediate through the pyrrolidone groups in the molecule, which is beneficial for obtaining nano-silica sol with uniform particle size and stable dispersion; Second, as an interface modifier, it can significantly improve the surface wettability of TiO2-modified porous carbon, promote the uniform spreading and firm anchoring of silica sol on the carbon matrix surface, and greatly improve the bonding strength; Third, its polymer chains can form abundant nanopores during the drying process, providing more active sites for the subsequent graft polymerization of functional monomers; Fourth, its strong hydrophilicity helps to improve the overall hydrophilicity of the final composite material, reduce the mass transfer resistance in the water treatment process, and has both excellent water solubility and alcohol solubility, and is easy to remove subsequently.

[0050] In some embodiments, the coating agent can be used directly before being mixed and reacted with the modified porous carbon material; alternatively, it can be first dissolved in a low-boiling-point alcohol solvent (e.g., at least one selected from ethanol, isopropanol, n-propanol, and tert-butanol) to prepare a coating agent solution, and then mixed and reacted with the modified porous carbon material.

[0051] Preferably, low-boiling-point alcohols are used as solvents, which have excellent solubility for coating agents, which helps to suppress the rapid hydrolysis of titanate on the surface of modified porous carbon materials, ensure the dispersion effect and the stability of subsequent reactions, and have excellent volatility and are easy to remove later.

[0052] Preferably, the concentration of the coating agent solution is 5~10 g / L. This concentration is conducive to the coating agent fully exerting its steric hindrance and interface modification effects, maintaining a suitable viscosity of the system, ensuring uniform dispersion of the modified porous carbon material, and not affecting subsequent operations.

[0053] In some embodiments, the mass ratio of the modified porous carbon material to the coating agent is 1:(0.5~3), preferably 1:(0.8~2) (or the mass-to-volume ratio of the modified porous carbon material to the coating agent solution is 1g:(100~300)mL). This ratio is beneficial for the modified porous carbon material to be fully wetted by the coating agent (solution), and for the coating agent to form a saturated adsorption layer on the particle surface, while taking into account both uniform dispersion and economical preparation.

[0054] Preferably, the temperature of the mixing reaction is 10~50℃, which is conducive to protecting the structural stability of the coating agent and allowing the dispersion effect to be stable; the reaction time is 0.5~1h, which is more conducive to the coating agent being fully adsorbed on the surface of the modified porous carbon material particles to form a stable dispersion system, taking into account both the dispersion effect and the reaction efficiency.

[0055] Preferably, the stirring rate of the mixing reaction is 200~300 r / min. This stirring rate is beneficial to enhancing the adsorption and steric hindrance effect of the coating agent, which is beneficial to the uniform dispersion of the modified porous carbon material in the solution, and at the same time, it is beneficial to ensure the stability and safety of the dispersion process.

[0056] Step (S5): Silica sol coating, introduction of thiol functionalization and particle forming In this invention, step (S5) is based on the structure-guiding and interface-regulating effect of the coating agent in step (S4). The silicon source reagent, silane coupling agent and the mixed reaction material are mixed and reacted for coating. After the reaction is completed, solid-liquid separation is performed. The modified porous carbon material coated with the obtained silica sol is washed, dried and granulated in sequence to obtain the first adsorbent material.

[0057] In this invention, coating is key to achieving a synergistic effect of high structural stability and high adsorption efficiency in the material. Its core lies in the ultrathin porous structure of the coating layer, which works collaboratively with the internal pores rather than competing with them. This step enhances the interfacial bonding between the silica sol and the substrate (modified porous carbon material), while introducing reactive thiol (-SH) active groups for subsequent functional monomer grafting polymerization, significantly improving the structural stability, water resistance, and potential for subsequent functionalization of the adsorbent material.

[0058] The inventors have discovered that the adsorbent material of this invention employs a multi-dimensional synergistic adsorption mechanism: the internal porous carbon framework provides physical adsorption sites, while the surface TiO2 layer, silica sol layer, and subsequent zwitterionic layer provide chemical adsorption and ion exchange sites; pore adsorption is only part of the adsorption mechanism. Therefore, this silica sol coating layer not only does not affect the adsorption performance but also overcomes the inherent defects of coal gasification slag-based materials, significantly improving the material's structural stability and long-term performance.

[0059] The inventors have also discovered that the coating layer of the present invention has the following advantages: First, the coating layer only covers the outer surface of the material and is much smaller than the overall size of the porous carbon particles (particle size 1~5 mm), so it does not penetrate into and block the macropores and mesopores adsorption channels inside the porous carbon, and the internal physical adsorption sites can function normally. Secondly, the silica sol layer itself has a porous structure (pore size 10~50 nm), which can serve as an additional adsorption medium, allowing small molecule pollutants and ions to pass freely and providing surface adsorption sites. Thirdly, this coating layer can effectively protect the internal pore structure from being destroyed by subsequent reactions, while significantly improving the overall mechanical strength and water resistance of the material, avoiding wear and breakage caused by water flow scouring and particle collision during water treatment, and preventing adsorption column blockage and material loss. Fourthly, this coating layer can effectively block trace harmful components that may exist in coal gasification slag, preventing them from seeping out during water treatment and improving the environmental safety of the material. Fifthly, as a universal interface, the silica sol layer can simultaneously form strong chemical bonds (such as CO-Si bonds and Si-O-polymer bonds) with the internal carbon skeleton and subsequent functional polymer layers, firmly anchoring the surface-active components to the material and significantly improving the material's recycling performance.

[0060] In some embodiments, in step (S5), the silicon source reagent is selected from at least one of tetraethyl orthosilicate (TEOS), propyl orthosilicate, butyl orthosilicate, and methyltriethoxysilane, or other conventional silicon source compounds that can be hydrolyzed to form silica sol. These silicon source reagents can all form a continuous and stable SiO2 sol coating layer through hydrolysis-condensation reaction under the control of a coating agent, providing rigid structural support for the adsorbent material.

[0061] Among them, tetraethyl orthosilicate has moderate hydrolytic activity and the best matching with the hydrogen bonding of the coating agent (especially PVP), which is conducive to the precise control of the nucleation and growth rate of silica sol particles, forming a uniform particle size and a complete SiO2 layer; propyl orthosilicate and butyl orthosilicate have milder hydrolytic rates, which is conducive to further improving the uniformity of the coating layer; methyltriethoxysilane can introduce methyl groups into the coating layer after hydrolysis, which is conducive to improving the water resistance and hydrophobicity of the adsorbent material and adapting it to different water treatment scenarios.

[0062] Preferably, the amount of silicon source reagent added is 1-5% based on the mass of the modified porous carbon material.

[0063] In some embodiments, in step (S5), the silane coupling agent is selected from at least one of mercaptotrimethoxysilane, mercaptotriethoxysilane, mercaptomethyltrimethoxysilane, mercaptomethyltriethoxysilane, mercaptomethyltripropoxysilane, or other mercapto-containing silane coupling agents.

[0064] This type of silane coupling agent contains both thiol (-SH) and alkoxy (-OCH3 or -OCH2CH3) molecules. The hydroxyl groups generated by the hydrolysis of alkoxy groups are more conducive to condensation reactions with the hydroxyl groups of the coating agent on the surface of the mixed reactants and the hydroxyl groups of the TiO2 layer, so as to achieve a firm bond between the silica sol coating layer and the substrate. On the one hand, the thiol group can directly form stable coordination bonds with heavy metal ions in water, improving the adsorption selectivity and adsorption capacity of the material. On the other hand, it can serve as an active site, providing an anchoring basis for the graft polymerization of zwitterionic functional monomers in subsequent steps.

[0065] Preferably, based on the mass of the modified porous carbon material, the amount of silane coupling agent added is 1-3%. This amount is beneficial for achieving a strong interface bond and for uniformly introducing sufficient thiol active groups onto the surface of the silica sol coating layer, ensuring the effect of subsequent functionalization modification, and without clogging the pore structure of the porous carbon material.

[0066] In some embodiments, in step (S5), the reaction coating temperature is 10~50°C. This temperature range is conducive to the synergistic hydrolysis and polycondensation of silicon source reagent and silane coupling agent, conducive to the formation of uniform silica sol particles under the control of coating agent (especially PVP), conducive to ensuring the continuity and uniformity of coating layer, and conducive to improving reaction efficiency and preparation economy.

[0067] Preferably, the reaction coating time is 1-3 hours. This duration is conducive to the full reaction between the silicon source reagent and the silane coupling agent, and to the formation of a structurally stable and uniform SiO2-thiol composite coating layer, thus balancing reaction efficiency and coating quality.

[0068] Preferably, continuous stirring at 200-300 r / min is maintained during the reaction coating process. This stirring rate facilitates the uniform dispersion of the silicon source reagent and silane coupling agent in the system, promotes sufficient contact with the dispersed substrate particles, helps avoid excessively rapid local hydrolysis and the formation of silica sol agglomerates, and further improves the integrity and uniformity of the coating layer.

[0069] In some embodiments, in step (S5), the product obtained after reaction coating is post-processed by washing to remove unreacted reagents and byproducts, drying to stabilize the material structure, and granulation to obtain a granular finished product with uniform particle size.

[0070] For example, the product obtained after reaction coating is first cooled to room temperature (e.g., 10–50 °C), and then solid-liquid separation is performed by vacuum filtration or centrifugation. For vacuum filtration, qualitative filter paper, quantitative filter paper, or microporous membranes with a pore size of 0.22–0.45 μm can be used, and the filtration pressure can be 0.05–0.1 MPa, which is more conducive to rapid separation of solid materials. For centrifugation, the rotation speed can be 3000–5000 r / min, and the separation time is 10–30 min.

[0071] In some embodiments, in step (S5), the washing can be performed using distilled water, deionized water, or solvents such as ethanol or isopropanol, and the washing is repeated 3 to 5 times until the filtrate is clear. This operation helps remove soluble impurities such as unreacted silicon source reagents, silane coupling agents, and hydrolysis byproducts from the system, which helps ensure the purity and adsorption performance of the adsorption material and helps reduce material agglomeration during the drying process.

[0072] In some embodiments, in step (S5), the drying temperature is 60-80°C, and the drying time is 2-4 hours. This combination of temperature and time is beneficial for quickly removing moisture after washing, for protecting the structural integrity of the silica sol coating layer, and for stabilizing the pore structure of the material. A moisture content of ≤5% in the dried material is beneficial for uniform particle formation during subsequent granulation, and for improving granulation efficiency and finished product quality.

[0073] In some embodiments, in step (S5), the granulation can be carried out using conventional granulation methods such as extrusion granulation, roll forming granulation, or spray forming. Among these, extrusion granulation allows for control of particle shape (e.g., cylindrical, spherical); roll forming is simple to operate and more conducive to large-scale mass production; and spray forming helps improve particle uniformity.

[0074] Preferably, a small amount of anhydrous ethanol or other low-toxicity and environmentally friendly binders can be added during the granulation process (the amount can be 1 to 2% of the mass of the dried material), which is beneficial to enhance the granulation effect, improve mechanical strength, and extend the service life and recycling number of the material in actual use.

[0075] Preferably, the particle size of the granulated adsorbent material is 1-5 mm. This particle size range is more conducive to subsequent filling into treatment equipment such as adsorption columns, which helps to reduce water flow resistance, improve water permeability, and ensure that the particles have sufficient specific surface area and adsorption sites, thereby achieving a synergistic improvement in application convenience and adsorption efficiency, and adapting to the actual engineering needs of various industrial wastewater treatment.

[0076] Optional step (S6): Thiol-initiated zwitterionic-acrylamide graft polymerization functionalization In this invention, to further improve the pollutant removal efficiency and anti-pollution performance of the adsorbent material for complex industrial wastewater, this step can be added after step (S5). This step utilizes the thiol (-SH) group introduced in step (S5) as a chain transfer agent and grafting anchor to initiate a free radical polymerization reaction between the zwitterionic functional monomer and the acrylamide comonomer, forming a uniform and stable polymer hydrogel functional layer in situ on the surface of the silica sol coating layer. This significantly optimizes the material's adsorption selectivity, mass transfer efficiency, and service life.

[0077] In some embodiments, in step (S6), the functional monomer is selected from at least one of N,N-dimethyl-N-acryloylethoxy-N-(3-sulfopropyl)-ammonium betaine, 2-(methylthio)ethylisobutenoyl-S-(sulfopropyl)-sulfonyl betaine, N,N-dimethyl-N-acrylamidopropyl-N-(2-carboxymethyl)-ammonium betaine, N,N-dimethyl-N-methacryloylethoxy-N-(3-sulfopropyl)-ammonium betaine, N,N-dimethyl-N-methacrylamidopropyl-N-(3-sulfopropyl)-ammonium betaine, or other conventional zwitterionic functional monomers.

[0078] These functional monomers possess a unique zwitterionic structure, offering the following advantages: First, their strong hydration capacity facilitates the formation of a stable hydration layer on the surface of the composite material (porous carbon + silica sol), effectively resisting the non-specific adsorption of complex organic matter in wastewater and significantly improving the material's anti-fouling performance; Second, the molecules simultaneously carry dimethylammonium ions (-N... + (CH3)2-) and sulfonic acid anion (-SO3) - Firstly, the amphoteric groups facilitate the efficient exchange and capture of anionic and cationic pollutants in water through electrostatic interactions. Secondly, the zwitterionic groups construct continuous ion transport channels on the material surface and within the pores, which helps to improve the selective adsorption and diffusion rate of target ions.

[0079] Preferably, based on the mass of the first adsorbent material, the amount of functional monomer is 10~30wt%. This dosage range is beneficial for fully utilizing the functional modification effect, broadening the pollutant removal range, and increasing the adsorption capacity. At the same time, it helps to avoid the polymerization products clogging the pores of the adsorbent material and ensures that the adsorption channels are unobstructed.

[0080] In some embodiments, in step (S6), the comonomer is selected from at least one of acrylamide, N-methylacrylamide, N-hydroxymethylacrylamide, N,N-dimethylacrylamide, methacrylamide, hydroxyethyl acrylate, and hydroxypropyl acrylate. Its core function is to co-polymerize with the functional monomer to form a polymer network with a suitable crosslinking density, providing rigid support for the stable loading of functional groups, and simultaneously enhancing the bonding strength between the functional layer and the silica sol coating layer.

[0081] Preferably, the comonomer is acrylamide. It has excellent water solubility and is well compatible with mixed solvents of low-carbon alcohols and weakly basic salts, which helps ensure uniform dispersion of the polymerization system. Its double bond reactivity is moderate, allowing for efficient synergistic polymerization with various zwitterionic functional monomers to form a structurally stable polymer hydrogel layer. The amide groups formed after polymerization can form hydrogen bonds with the hydroxyl groups on the silica sol surface, further enhancing the adhesion between the functional layer and the substrate.

[0082] Preferably, based on the mass of the first adsorbent material, the amount of the polymeric monomer is 5-20 wt%. This amount is beneficial for forming a sufficient cross-linked structure with the functional monomer, ensuring the stability of the functional layer structure, and at the same time, it helps to avoid the polymeric product from excessively occupying the porous space, ensuring that the adsorption channels of the adsorbent material are unobstructed.

[0083] In some embodiments, in step (S6), the mixed solvent is a low-carbon alcohol-weakly basic salt mixed solvent system, such as an aqueous solution of ethanol / ammonium bicarbonate, an aqueous solution of isopropanol / potassium bicarbonate, an aqueous solution of propanol / sodium bicarbonate, an aqueous solution of ethanol / sodium bicarbonate, etc.

[0084] Among them, weakly alkaline salts (such as ammonium bicarbonate, potassium bicarbonate, and sodium bicarbonate) are beneficial to providing a stable weakly alkaline environment (pH 8-9), which promotes the efficient free radical polymerization reaction of functional monomers and comonomers. In particular, ammonium bicarbonate slowly decomposes at the polymerization reaction temperature to produce NH3 and CO2 gases. When the gases escape from the inside of the polymer layer, they will form a large number of nanoscale interconnected pores in situ, further increasing the mass transfer channels of the functional layer and improving the ion diffusion rate.

[0085] Among them, low-carbon alcohols (such as ethanol, isopropanol, and propanol) are beneficial for flexibly adjusting the polarity of the system, effectively preventing the aggregation of polymerization products, and improving the compatibility between the adsorbent material and the solution.

[0086] Preferably, based on the mass of the first adsorbent material, the amount of the mixed solvent is 100~300 mL / g. This amount is beneficial for fully wetting the adsorbent material, ensuring sufficient contact between each monomer and the material surface, and balancing reaction efficiency and preparation economy.

[0087] More preferably, the mixed solvent is an aqueous solution of ethanol, ammonium bicarbonate and water in a volume-mass ratio of (20~40) mL:(2~5) g:100 mL.

[0088] This ratio helps to stabilize the pH of the system within an optimal range, maximizing the activity of the initiator; it also helps to adjust the polarity of the system, improving monomer solubility and material wettability.

[0089] In some embodiments, in step (S6), the mass ratio of the first adsorbent material, the functional monomer, and the comonomer is 1:(0.1~0.3):(0.05~0.2). This ratio is beneficial for the functional monomer to fully cover the surface of the adsorbent material, thereby enhancing the adsorption function of pollutants; it is beneficial for the comonomer and the functional monomer to form a matched cross-linked network, ensuring the stability of the functional layer structure; and it is beneficial for maximizing the retention of the porous structure of the adsorbent material while allowing the functional groups to be uniformly loaded.

[0090] In some embodiments, in step (S6), the initiator is selected from at least one of ammonium persulfate, potassium persulfate, sodium persulfate, dimethyl azobisisobutyrate, azobisisobutyronitrile, azobisisobutyronitrile, benzoyl peroxide, and benzoyl tert-butyl peroxide, or other conventional free radical initiators. Among these, ammonium persulfate and potassium persulfate are water-soluble initiators, more suitable for aqueous or alcohol-water mixed systems; azobisisobutyronitrile and dimethyl azobisisobutyrate are oil-soluble initiators, more suitable for high-proportion alcohol phase systems. Preferably, based on the mass of the first adsorbent material, the amount of initiator added is 0.2~1.8% (or 0.2~0.6% of the mass of the functional monomer). This amount helps to ensure initiation efficiency, ensures that the polymerization reaction proceeds fully, and at the same time helps to ensure a uniform molecular weight distribution of the polymerization product and improve the stability of the modification effect.

[0091] In some embodiments, in step (S6), the reaction temperature is 30~100℃ and the reaction time is 1~3h. This temperature range can be flexibly adjusted according to the type of initiator (for example, ammonium persulfate is suitable for 60~80℃, and azobisisobutyronitrile is suitable for 50~70℃), which is beneficial for adapting to the optimal activity temperature of different initiators and ensuring that the reaction proceeds efficiently and stably.

[0092] Preferably, after the reaction is completed, the mixture is cooled to room temperature (e.g., 10~50 °C) before solid-liquid separation (the operation method can be referred to step S6), which is more conducive to the structural integrity of the material.

[0093] Preferably, the solid product obtained after solid-liquid separation is washed with distilled water or deionized water until the filtrate is clear, so as to fully remove unreacted monomers, initiators and other impurities.

[0094] Preferably, the drying temperature is 60~80℃, so that the moisture content is ≤5% (the time can be 2~4 h).

[0095] Preferably, after drying, the material can be granulated according to application requirements (the operation method can be referred to step S6), and the particle size of the second adsorbent material after granulation is 1~5 mm.

[0096] Adsorbent materials A second aspect of the present invention provides an adsorbent material obtained according to the above method.

[0097] In some embodiments, the adsorbent material is granular with a particle size of 1-5 mm, a moisture content of ≤5%, and a specific surface area of ​​300-800 m². 2 / g, with a porosity of 40%~70%. It uses porous carbon derived from coal gasification slag obtained by inert calcination in step (S1) as the core substrate, and the surface is sequentially loaded with TiO2-carboxylate composite modification layer generated in situ in step (S3), silica sol-thiol coating layer formed in step (S5), preferably after functional modification in step (S6), the outermost layer is a zwitterionic-acrylamide copolymer hydrogel functional layer with unobstructed internal pore channels.

[0098] In some embodiments, the surface of the adsorbent material functionalized in step (S6) is uniformly distributed with sulfonyl sulfonyl (-SO3-) and dimethylammonium (-N) groups. + Functional groups such as (CH3)2-) are present. The compressive strength of the adsorbent material is 30~50 MPa, and it exhibits excellent chemical stability within the temperature range of 20~80℃, with no obvious structural damage or functional layer detachment.

[0099] In some embodiments, the carbon content of the adsorbent material is 20%~50% (based on the characteristics of coal gasification slag raw material), and the static saturated adsorption capacity for typical pollutants in water is ≥50 mg / g (in Cu). 2+ (Calculation), possessing highly efficient basic adsorption potential.

[0100] Applications of adsorbent materials The third aspect of this invention provides the use of the above-mentioned adsorbent material, which is suitable for various wastewater treatment scenarios and can be widely used for the adsorption and treatment of water pollutants, especially for industrial wastewater treatment, including treated wastewater from coal-fired power plants, coal chemical wastewater, and mine wastewater containing heavy metals, etc., with a focus on removing heavy metal ions (Cu) from the water. 2+ Pb 2+ Cr 3+ Pollutants such as salts (chloride ions, calcium and magnesium ions) and COD.

[0101] In some embodiments, the adsorbent material is particularly suitable for treating clean wastewater generated by coal-fired power plants. This type of wastewater is typically characterized by high salinity and high ion concentration, with a TDS content of 3000-4000 mg / L, of which Na... + The content is 2500~3200 mg / L, Ca 2+ The content is 350~450 mg / L, Cl - The concentration is 3000~3600 mg / L, and it also contains pollutants such as COD, ammonia nitrogen, and suspended solids. The adsorption material of this invention can efficiently treat this type of complex wastewater through a synergistic design of "porous carbon physical adsorption + TiO2 chemical adsorption + silica sol structural support + zwitterionic functionalization".

[0102] In some embodiments, when the adsorbent material is used for wastewater treatment (preferably clean wastewater from coal-fired power plants), the process conditions are: adsorption temperature 20~40℃, wastewater pH 5~9, liquid-to-solid ratio (wastewater volume to adsorbent mass ratio) 50~200:1, and adsorption time 0.5~2h; under these conditions, the removal rate of heavy metal ions is ≥85%, and the removal rate of salt is ≥40%.

[0103] In some embodiments, the adsorbent material has good recyclability, and its recycling process is as follows: adsorption saturation → elution regeneration → washing with water to neutrality → re-adsorption; 0.1~0.5mol / L hydrochloric acid solution can be used as the eluent, which can efficiently desorb the adsorbed ionic pollutants and restore the active sites of the material; after 3~5 adsorption-desorption cycles, the material can still maintain more than 80% of the initial performance in terms of pollutant removal rate.

[0104] In some implementations, the material can also be extended to other industrial wastewater treatment, conventional water treatment pretreatment, or emergency heavy metal adsorption scenarios in water bodies.

[0105] The following detailed description uses specific embodiments. It should be noted that the coal gasification slag used in the embodiments and comparative examples is the coal gasification coarse slag of Xinjiang Chemical Co., Ltd. of China Energy Investment Corporation. It is black glassy particles with a dense, glossy, glazed surface.

[0106] Example 1 (IE1) (S1) Under a nitrogen atmosphere, the coal gasification slag is calcined. After the reaction is completed, it is cooled to room temperature. The resulting product is washed and dried to obtain porous carbon material. The calcination temperature is 900℃ and the time is 3 hours.

[0107] (S2) The titanate and carboxylate are mixed and then added to ethyl acetate for ultrasonic dissolution and dispersion to obtain a mixed organic solution; wherein, The titanate is isopropyltris(stearoyl) titanate, and the carboxylate is sodium malate, and the mass ratio of them is 1:3. The organic solvent is ethyl acetate.

[0108] (S3) The porous carbon material obtained in step (S1) is added to the mixed organic solution obtained in step (S2), and the mixture is stirred at 70°C until the organic solvent has completely evaporated. After the reaction is complete, the resulting product is dried to obtain the modified porous carbon material; wherein, The mass-to-volume ratio of the porous carbon material to the mixed organic solvent is 1 g: 400 mL.

[0109] (S4) Polyvinylpyrrolidone is dissolved in anhydrous ethanol to obtain a polyvinylpyrrolidone solution. Then, the modified porous carbon material obtained in step (S3) is added to the polyvinylpyrrolidone solution, and the mixture is stirred continuously at room temperature to obtain a mixed reaction mixture. The concentration of the polyvinylpyrrolidone solution is 7.5 g / L; The mass-to-volume ratio of the modified porous carbon material to the polyvinylpyrrolidone solution is 1 g: 200 mL; The stirring time is 45 minutes.

[0110] (S5) Tetraethyl orthosilicate and mercaptomethyltrimethoxysilane are added sequentially to the mixed reaction mixture obtained in step (S4), and the reaction is continuously stirred to obtain a modified porous carbon material coated with silica sol; the modified porous carbon material coated with silica sol is then subjected to solid-liquid separation, washing, drying, and granulation to obtain a first adsorbent material with a particle size of 5 mm; wherein, Based on the mass of the modified porous carbon material, the amount of tetraethyl orthosilicate added is 3%, and the amount of mercaptomethyltrimethoxysilane added is 2%. The stirring reaction was carried out for 2 hours.

[0111] Example 2 (IE2) The procedure is the same as in Example 1, except that: In step (S1), the calcination temperature of the coal gasification slag is 1000℃ and the time is 2h.

[0112] In step (S2), the titanate is tetraisopropyl titanate, the carboxylate is sodium oxalate, and their mass ratio is 1:5; the organic solvent is N,N-dimethylformamide.

[0113] In step (S3), the mass-to-volume ratio of the porous carbon material to the mixed organic solution is 1 g: 200 mL.

[0114] In step (S4), the concentration of the polyvinylpyrrolidone solution is 5 g / L; the mass-to-volume ratio of the modified porous carbon material to the polyvinylpyrrolidone solution is 1 g: 300 mL; and the stirring time is 30 min.

[0115] In step (S5), based on the mass of the modified porous carbon material, the amount of tetraethyl orthosilicate added is 5%, and the amount of mercaptomethyltrimethoxysilane added is 1%; the stirring reaction time is 3 hours.

[0116] Example 3 (IE3) The procedure is the same as in Example 1, except that: In step (S1), the calcination temperature of the coal gasification slag is 800°C and the time is 4 hours.

[0117] In step (S2), the titanate is tetraisopropyl di(dioctyl phosphite) titanate, the carboxylate is sodium tartrate, and their mass ratio is 1:1; the organic solvent is petroleum ether.

[0118] In step (S3), the mass-to-volume ratio of the porous carbon material to the mixed organic solution is 1 g: 600 mL.

[0119] In step (S4), the concentration of the polyvinylpyrrolidone solution is 10 g / L; the mass-to-volume ratio of the modified porous carbon material to the polyvinylpyrrolidone solution is 1 g: 100 mL; and the stirring time is 60 min.

[0120] In step (S5), based on the mass of the modified porous carbon material, the amount of tetraethyl orthosilicate added is 1%, and the amount of mercaptomethyltrimethoxysilane added is 3%; the stirring reaction time is 1 hour.

[0121] Example 4 (IE4) The procedure is the same as in Example 1, except that a new step (S6) is added: The first adsorbent material obtained in step (S5), the functional monomer, and acrylamide were added to an ethanol / ammonium bicarbonate aqueous solution, mixed, and stirred until homogeneous. Then, ammonium persulfate was added and the mixture was stirred at 70°C. After the reaction was complete, the mixture was cooled to room temperature, filtered, and the resulting solid product was washed, dried, and granulated to obtain a second adsorbent material with a particle size of 5 mm. The functional monomer is N,N-dimethyl-N-acryloylethoxy-N-(3-sulfopropyl)-ammonium betaine; The mass ratio of the first adsorbent material, the functional monomer, and acrylamide is 1:0.2:0.1; The ethanol / ammonium bicarbonate aqueous solution is obtained by mixing ethanol, ammonium bicarbonate and water in a volume-mass ratio of 30 mL: 3.5 g: 100 mL. The amount of ammonium persulfate added is 0.4% of the mass of the functional monomer; The stirring reaction was carried out for 2 hours.

[0122] Example 5 (IE5) The procedure is carried out in accordance with Example 4, except that in step (S6): The functional monomer is 2-(methylthio)ethylisobutenoyl-S-(sulfopropyl)-sulfobutyrine; The mass ratio of the first adsorbent material, the functional monomer, and acrylamide is 1:0.2:0.1; The ethanol / ammonium bicarbonate aqueous solution is obtained by mixing ethanol, ammonium bicarbonate and water in a volume-mass ratio of 20mL:2g:100mL. The amount of ammonium persulfate added is 0.2% of the mass of the functional monomer; The stirring reaction was carried out over a period of 3 hours.

[0123] Example 6 (IE6) The procedure is carried out in accordance with Example 4, except that in step (S6): The functional monomer is N,N-dimethyl-N-methacrylamidopropyl-N-(3-sulfopropyl)-ammonium betaine; The mass ratio of the first adsorbent material, the functional monomer, and acrylamide is 1:0.3:0.1; The ethanol / ammonium bicarbonate aqueous solution is obtained by mixing ethanol, ammonium bicarbonate and water in a volume-mass ratio of 40mL:5g:100mL. The amount of ammonium persulfate added is 0.6% of the mass of the functional monomer; The stirring reaction was carried out for 1 hour.

[0124] Comparative Example 1 (CE1) The procedure is the same as in Example 1, except that: In step (S2), the mixed organic solution contains only titanate and organic solvent, and does not contain carboxylates.

[0125] Comparative Example 2 (CE2) The procedure is the same as in Example 1, except that: In step (S2), the mixed organic solution contains only carboxylates and organic solvents, and does not contain titanates.

[0126] Comparative Example 3 (CE3) The procedure is the same as in Example 1, except that: Steps (S2) and (S3) are skipped, and the porous carbon material obtained in step (S1) is directly used as a modified porous carbon material in step (S4).

[0127] Comparative Example 4 (CE4) The procedure is the same as in Example 1, except that: Only steps (S1) to (S3) are performed, and the modified porous carbon material obtained in step (S3) is directly used as an adsorbent.

[0128] Experimental Example 1: Removal Effect of Different Products on Pollutants in Wastewater from Coal-fired Power Plants Wastewater from a coal-fired power plant in the Hongshaquan mining area was taken as a water sample for treatment. The water quality of the sample was as follows: conductivity 2250 μS / cm, COD 545 mg / L, ammonia nitrogen 324 mg / L, salinity 3516 mg / L, total chlorine 3340 mg / L, suspended solids 254 mg / L, and sodium... + The content is 2950 mg / L, Ca 2+ The content is 410 mg / L, Mg 2+ The content is 105 mg / L, HCO3 - The content is 75.5 mg / L, K + The content was 21.2 mg / L, SO4 2- The content is 495 mg / L, NO3 - The content is 64.6 mg / L.

[0129] The collected water samples were divided into 10 portions, each 200 mL, numbered 1 to 10. The adsorbent materials prepared in Examples 1-6 and Comparative Examples 1-4 of this invention were then added sequentially to water samples 1-10. The concentration of the product in each example and comparative example in the water sample was 100 mg / L. After addition, the mixture was stirred at 60 rpm for 10 min, then allowed to stand for 30 min. The supernatant was then collected for relevant index detection, and the removal rate of each index was calculated (results are shown in Table 1 below). Removal rate (%) = (Original water sample index - Treated water sample index) / Original water sample index × 100%.

[0130] Table 1: Changes in various indicators of the treated water sample

[0131] As can be seen from the results in Table 2, compared with the original water sample, all indicators of the treated water sample showed a certain degree of reduction. Among them, compared with Comparative Examples 1-4, the products obtained in Examples 1-6 of this invention had a higher removal rate of each indicator in the water sample; while compared with Examples 1-3, the water sample indicators of Examples 4-6 showed a significant decrease and a significant increase in removal rate after treatment, indicating that further modification of the material (step S4) can significantly improve the removal effect of the obtained product on pollutants in the water sample.

[0132] Test Example 2: Cyclic Performance Test of Different Products To further verify the cycle stability of the composite material obtained in this invention and to compare the effects of different modification processes on regeneration performance, the composite materials prepared in Examples 1, 4 and Comparative Examples 1 to 4 were selected respectively, and adsorption-regeneration cycle tests were conducted using clean wastewater (water quality parameters as shown in Table 1) from a coal-fired power plant in the Hongshaquan mining area.

[0133] Take 200 mL of each of the above water samples and add 100 mg / L of the prepared adsorbent material. Stir at 60 rpm for 10 min, let stand for 30 min, and then take the supernatant to determine the pollutant index and calculate the initial removal rate. After adsorption saturation, the material is separated by vacuum filtration, washed three times with deionized water, and then immersed and stirred in 0.1 mol / L hydrochloric acid solution for 2 h for elution and regeneration. It is then washed with deionized water until neutral and dried at 60℃ to complete the first regeneration.

[0134] Repeat the "adsorption-regeneration" steps described above for a total of 5 cycles. After each cycle, measure the material's effect on Ca. 2+ The removal rates of (representative cations) and total chlorine (representative anions) were calculated, and the removal rate retention rate after the 5th cycle was calculated based on the initial removal rate. The results of the cycle test are shown in Table 3 below.

[0135] The removal rate retention rate (%) is calculated as follows: (Removal rate in the 5th cycle / Removal rate in the first cycle) × 100%.

[0136] Table 3: Comparison of Cyclic Performance of Different Composite Materials (Retention Rate after 5th Cycle)

[0137] As shown in Table 3, in terms of initial adsorption performance: Example 4 > Example 1 > Comparative Examples 1-3 > Comparative Example 4, demonstrating the necessity of polymerization modification and titanate / carboxylate composite modification. In terms of cycle stability: Example 4 had the highest retention rate (above 94%), followed by Example 1 (around 90%), while the comparative examples were all below 77%.

[0138] Experimental results show that the adsorbent material prepared by the present invention has excellent cycle stability: the silica sol coating layer can significantly improve the structural strength of the material and prevent particle breakage and loss; the zwitterionic polymer crosslinking layer can firmly anchor the surface active components and prevent them from falling off during regeneration. The synergistic effect of the two allows the material to maintain more than 94% of its initial performance after 5 adsorption-desorption cycles, greatly improving the economy and practicality of engineering applications.

[0139] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the methods and techniques disclosed above without departing from the scope of the present invention to create equivalent embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing an adsorbent material using coal gasification slag, characterized by, The method includes the following steps: (S1) The coal gasification slag is calcined under an inert atmosphere to obtain porous carbon material; (S2) Dissolve the titanate and carboxylate in an organic solvent to obtain a mixed organic solution; (S3) The porous carbon material is added to the mixed organic solution for modification treatment to obtain modified porous carbon material; (S4) The modified porous carbon material is mixed with a coating agent and subjected to a mixing reaction to obtain a mixed reaction material; (S5) The silicon source reagent, silane coupling agent and the mixed reaction material are mixed and reacted and coated. After the reaction is completed, solid-liquid separation is performed, and the modified porous carbon material coated with the obtained silica sol is washed, dried and granulated in sequence to obtain the first adsorbent material.

2. The method of claim 1, wherein, In step (S1), The coal gasification slag is at least one of coal gasification coarse slag and coal gasification fine slag; The calcination reaction is carried out at a temperature of 800~1000℃ for 2~4 hours. The inert atmosphere is selected from at least one of nitrogen, argon and helium.

3. The method according to claim 1 or 2, characterized in that, In step (S2), The titanate is selected from at least one of tetraisopropyl titanate, tetrabutyl titanate, trifluoroacetyl titanate, chloroisopropyl tris(dioctylphosphoyloxy) titanate, isopropyl tris(stearoyl) titanate, di(dioctylpyrophosphoyloxy)oxoacetate titanate, and di(dioctyl phosphite) tetraisopropyl titanate; preferably selected from at least one of tetraisopropyl titanate, tetrabutyl titanate, and trifluoroacetyl titanate. The carboxylate is selected from at least one of sodium tartrate, sodium oxalate, sodium malate, sodium citrate dihydrate, and sodium salicylate; The organic solvent is selected from at least one of petroleum ether, diethyl ether, ethyl acetate, and N,N-dimethylformamide; Preferably, the mass ratio of the titanate to the carboxylate is 1:(1~5).

4. The method according to any one of claims 1 to 3, characterized in that, In step (S3), The mass ratio of the porous carbon material to the total mass of titanate and carboxylate in the mixed organic solution is 1:(0.08~0.25); Preferably, the modification treatment is performed at a temperature of 60-80°C for 1-3 hours. More preferably, after the modification treatment is completed, the reaction product is dried at a temperature of 50-60°C for 1-2 hours.

5. The method according to any one of claims 1 to 4, characterized in that, In step (S4), The coating agent is selected from at least one of polyvinylpyrrolidone, polyethylene glycol, polyacrylamide, hydroxypropyl methylcellulose and polyethylene oxide, preferably polyvinylpyrrolidone; Preferably, the mass ratio of the modified porous carbon material to the coating agent is 1:(0.5~3), more preferably 1:(0.8~2); Preferably, the temperature of the mixing reaction is 10~50℃ and the time is 0.5~1h; More preferably, before the coating agent is mixed and reacted with the modified porous carbon material, it is first dissolved in a solvent containing at least one of ethanol, isopropanol, n-propanol and tert-butanol to form a coating agent solution with a concentration of 5-10 g / L, and then mixed and reacted with the modified porous carbon material.

6. The method according to any one of claims 1 to 5, characterized in that, In step (S5), The silicon source reagent is selected from at least one of tetraethyl orthosilicate, propyl orthosilicate, butyl orthosilicate, and methyltriethoxysilane; preferably tetraethyl orthosilicate. The silane coupling agent is selected from any one of mercaptotrimethoxysilane, mercaptotriethoxysilane, mercaptomethyltrimethoxysilane, mercaptomethyltriethoxysilane, and mercaptomethyltripropoxysilane. Preferably, based on the mass of the modified porous carbon material, the amount of silicon source reagent added is 1-5%, and the amount of silane coupling agent added is 1-3%. Preferably, the reaction coating temperature is 10~50 ℃ and the time is 1~3 h.

7. The method according to any one of claims 1 to 6, characterized in that, The method further includes step (S6): uniformly mixing the first adsorbent material, functional monomer, comonomer and mixed solvent, adding an initiator to carry out the reaction; after the reaction is completed, performing solid-liquid separation and washing, drying and granulating the obtained product in sequence to obtain the second adsorbent material; Preferably, in step (S6): The functional monomer is selected from at least one of N,N-dimethyl-N-acryloylethoxy-N-(3-sulfopropyl)-ammonium betaine, 2-(methylthio)ethylisobutenoyl-S-(sulfopropyl)-sulfonyl betaine, N,N-dimethyl-N-acrylamidopropyl-N-(2-carboxymethyl)-ammonium betaine, N,N-dimethyl-N-methacryloylethoxy-N-(3-sulfopropyl)-ammonium betaine, and N,N-dimethyl-N-methacrylamidopropyl-N-(3-sulfopropyl)-ammonium betaine; The comonomer is selected from at least one of acrylamide, N-methylacrylamide, N-hydroxymethylacrylamide, N,N-dimethylacrylamide, methacrylamide, hydroxyethyl acrylate, and hydroxypropyl acrylate; preferably acrylamide; The mixed solvent is an aqueous solution of ethanol / ammonium bicarbonate, an aqueous solution of isopropanol / potassium bicarbonate, an aqueous solution of propanol / sodium bicarbonate, or an aqueous solution of ethanol / sodium bicarbonate; more preferably, it is an aqueous solution of ethanol / ammonium bicarbonate in a volume-mass ratio of (20~40) mL:(2~5) g:100 mL. The initiator is selected from at least one of ammonium persulfate, potassium persulfate, sodium persulfate, dimethyl azobisisobutyrate, azobisisobutyronitrile, azobisisobutyronitrile, benzoyl peroxide, and tert-butyl peroxide. Preferably, based on the mass of the first adsorbent material, the amount of the functional monomer added is 10-30 wt%, the amount of the polymerizable monomer added is 5-20 wt%, the amount of the mixed solvent added is 100-300 mL / g, and the amount of the initiator added is 0.2-1.8 wt%. Preferably, the reaction temperature is 30~100 ℃ and the time is 1~3 h.

8. The method according to any one of claims 1 to 7, characterized in that, In step (S5) and / or step (S6), After the reaction is complete, the mixture is cooled to 10-50°C before solid-liquid separation is performed. The solid-liquid separation is carried out by vacuum filtration or centrifugation. And / or, the washing is performed using distilled water, deionized water or anhydrous ethanol, until the filtrate is clear; And / or, the drying temperature is 60~80℃, and the moisture content of the material after drying is ≤5%; And / or, 1-2% of the mass of the dried material or a binder is added during the granulation process; And / or, the particle size of the first adsorbent material and / or the second adsorbent material is 1~5mm.

9. An adsorbent material obtained by the method according to any one of claims 1 to 8, characterized in that, The adsorbent material has a particle size of 1~5mm, a water content of ≤5%, a specific surface area of ​​300~800m2 / g, and a porosity of 40%~70%.

10. The use of an adsorbent material obtained by the method according to any one of claims 1 to 8 or an adsorbent material according to claim 9 for treating wastewater from coal-fired power plants; wherein, The TDS content of the clean water of the coal-fired power plant is 3000-4000 mg / L, wherein the Na + content is 2500-3200 mg / L, the Ca 2+ content is 350-450 mg / L, and the Cl - content is 3000-3600 mg / L. Preferably, the process conditions are as follows: adsorption temperature 20~40℃, pH 5~9, volume ratio of clean wastewater from coal-fired power plants to adsorption material of (50~200):1, and adsorption time 0.5~2 h.

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