Porous adsorption material for acid mine wastewater treatment and preparation method thereof

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly relates to a porous adsorption material for acid mine wastewater treatment and a preparation method thereof.The porous adsorption material is prepared from, by weight, 55-80 parts of modified bentonite, 10-20 parts of a carbon source, 1-4 parts of L-cysteine, 5-21 parts of GPTMS, 10-35 parts of DMC, 5-21 parts of DMA, 2.5-10.5 parts of a pore-foaming agent and 0.5-2.1 parts of ammonium persulfate; acid activated bentonite nanosheets are used as a framework and are cross-linked with S-CDs and GPTMS through covalent bonds and non-covalent bonds to form a rigid-flexible organic-inorganic hybrid three-dimensional network, multiple adsorption sites are introduced through DMC and DMA in-situ polymerization, a gel structure with hierarchical pore channels is constructed under the action of a pore-foaming agent, and stable structure in a strongly acidic environment is realized. And heavy metal cations and sulfate anions can be synchronously and efficiently adsorbed.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and relates to a porous adsorption material for treating acidic mine wastewater and its preparation method. Background Technology

[0002] Acid mine drainage (AMD) is a major source of environmental pollution generated during mining, mineral processing, and smelting. It occurs when sulfide minerals (such as pyrite) in the strata are exposed to air and water, undergoing oxidation and microbial action to produce sulfuric acid. This leads to a significant drop in the pH of the water (usually below 4) and the dissolution of large amounts of heavy metal ions (such as Fe). 2+ Fe 3+ Cu 2+ Zn 2+ Pb 2+ Cd 2+ Hg 2+ etc.) and sulfate ions (SO4) 2- If such wastewater is discharged directly, it will cause continuous pollution to surface water and groundwater, damage aquatic ecosystems, and may accumulate through the food chain, threatening human health.

[0003] Currently, the main treatment methods for acidic mine wastewater include neutralization, adsorption, chemical precipitation, biological methods, and constructed wetland technology. Among these, adsorption has become a research and application hotspot due to its advantages such as simple operation, wide applicability, relatively low cost, and low likelihood of secondary pollution. Bentonite, a natural layered silicate clay mineral, is mainly composed of montmorillonite. It possesses characteristics such as large specific surface area, strong ion exchange capacity, and good adsorption performance, and is considered to have broad application potential in wastewater treatment.

[0004] However, the direct use of natural bentonite in AMD treatment has significant limitations: firstly, its structure is unstable in strongly acidic environments, and the aluminum-oxygen octahedrons in its framework are easily destroyed by H+. + Erosion leads to structural damage and the leaching of aluminum ions, causing secondary pollution; secondly, although its interlayer domains possess cation exchange capacity, they are not conducive to Fe... 2+ / Fe 3+ The adsorption capacity of certain metal ions is limited, especially for SO4. 2- The adsorption capacity of anions is weaker and the selectivity is not high; in addition, its layered structure dominated by micropores restricts the diffusion efficiency of pollutant molecules and affects the overall adsorption kinetics performance.

[0005] Therefore, developing a novel bentonite-based porous adsorption material that combines strong acid stability, high adsorption capacity, and the ability to simultaneously remove anionic and cationic pollutants is of great significance for promoting the efficient and economical treatment of acidic mine wastewater. Summary of the Invention

[0006] To address the shortcomings of the existing technologies, this invention provides a porous adsorbent material for treating acidic mine wastewater and its preparation method. This porous adsorbent material uses acid-activated bentonite nanosheets as a framework, which are cross-linked with S-CDs (thiolized biomass carbon dots) and silane coupling agents through covalent and non-covalent bonds to form a "rigid-flexible" organic-inorganic hybrid three-dimensional network. Furthermore, multiple adsorption sites are introduced through in-situ polymerization of functional monomers, constructing a gel structure with hierarchical pores. This achieves structural stability in strongly acidic environments and enables the simultaneous and efficient adsorption of heavy metal cations and sulfate anions.

[0007] This invention provides a porous adsorbent material for treating acidic mine wastewater. The porous adsorbent material comprises the following raw materials in parts by weight: 55-80 parts modified bentonite, 10-20 parts carbon source, 1-4 parts L-cysteine, 5-21 parts GPTMS (γ-(2,3-epoxypropoxy)propyltrimethoxysilane), 10-35 parts DMC ([2-(methacryloyloxy)ethyl]trimethylammonium chloride), 5-21 parts DMA (dopamine methacrylamide), 2.5-10.5 parts pore-forming agent, and 0.5-2.1 parts ammonium persulfate.

[0008] Furthermore, the modified bentonite comprises the following raw materials: sodium bentonite and urea, wherein the mass ratio of sodium bentonite to urea is 7-12:1.

[0009] Furthermore, the preparation method of the modified bentonite includes the following steps:

[0010] S1: Weigh 65-90 parts of sodium-based bentonite, disperse it in deionized water, stir evenly to obtain a suspension;

[0011] S2: Weigh 8-12 parts of urea and slowly add it to the suspension at 70°C with continuous stirring. After the reaction is complete, centrifuge and wash to obtain the precipitate.

[0012] S3: The precipitate is dried at 60°C and ground to obtain modified bentonite.

[0013] Furthermore, the carbon source is selected from any one of citric acid, starch, and cellulose.

[0014] Furthermore, the pore-forming agent is selected from any one of PVP (polyvinylpyrrolidone), NaCl (sodium chloride), and PEG (polyethylene glycol).

[0015] This invention also provides a method for preparing porous adsorbent materials for treating acidic mine wastewater, specifically including the following steps:

[0016] Step 1: Weigh 55-80 parts of modified bentonite, disperse it in 1 mol / L hydrochloric acid solution, centrifuge and wash until neutral, redisperse it in water to obtain bentonite nanosheet colloidal suspension;

[0017] Step 2: Weigh 10-20 parts of carbon source and 1-4 parts of L-cysteine, dissolve them in deionized water to obtain a mixed solution, transfer the mixed solution to a high-pressure hydrothermal reactor for hydrothermal reaction, and then perform dialysis to obtain an S-CDs aqueous solution.

[0018] Step 3: Weigh out 5-21 parts of S-CDs aqueous solution and GPTMS, and add them to the bentonite nanosheet colloidal suspension under stirring conditions. Mix them evenly to obtain the primary hybrid gel.

[0019] Step 4: Weigh 10-35 parts of DMC, 5-21 parts of DMA, 2.5-10.5 parts of porogen, and 0.5-2.1 parts of ammonium persulfate, add them together to the nascent hybrid gel, mix them evenly, and carry out in-situ free radical polymerization under nitrogen protection to obtain crude adsorbent material.

[0020] Step 5: After washing, drying, crushing and sieving the crude adsorbent material, a porous adsorbent material for treating acidic mine wastewater is obtained.

[0021] The beneficial effects achieved by this invention are as follows:

[0022] The porous adsorbent material for treating acidic mine wastewater prepared in this invention achieves synergistic optimization of material structure and performance through an innovative "pre-intercalation-hybrid crosslinking-functional polymerization" preparation process. The components in the material exert multiple synergistic effects through precise design: the modified bentonite nanosheets formed after acid activation provide a stable framework structure and abundant active sites; the thiolized biomass carbon dots exhibit specific coordination with heavy metal ions through surface-modified thiol groups (-SH); and the quaternary ammonium salt groups in DMC efficiently capture SO4 through electrostatic interactions. 2- The catechol group in dopamine methacrylamide forms strong complexes with various metal ions, thus constructing a multi-mechanism synergistic adsorption system of "electrostatic adsorption-coordination bonding-specific binding".

[0023] This invention significantly improves the structural stability and adsorption performance of materials by constructing a "rigid-flexible" organic-inorganic hybrid three-dimensional network. Bentonite nanosheets provide a rigid framework, while silane coupling agent (GPTMS) and thiolized biomass carbon dots form a flexible interconnected network through covalent cross-linking. This unique structural design allows the material to maintain its structural integrity in a strongly acidic environment (pH < 4), effectively avoiding the structural collapse and aluminum ion dissolution problems of traditional bentonite materials.

[0024] Through the in-situ polymerization of functional monomers (DMC and DMA) and the synergistic effect of porogens, a hierarchical porous structure was successfully constructed in a hybrid network. Macropores provide rapid mass transfer channels, mesopores increase specific surface area, and micropores provide specific adsorption sites. This hierarchical porous structure significantly improves the diffusion rate and adsorption capacity of pollutants. Simultaneously, the interconnected channels formed by the porogen during polymerization provide abundant transport pathways for pollutant molecules, effectively improving adsorption kinetics.

[0025] The porous adsorption material for treating acidic mine wastewater provided by this invention employs multiple adsorption mechanisms and intelligent pore structure design, possessing outstanding advantages such as good acid stability, large adsorption capacity, and strong selectivity, and has broad application prospects and industrialization value. Attached Figure Description

[0026] Figure 1 Scanning electron microscope image of the porous adsorbent material prepared in Example 1 at low magnification (250x);

[0027] Figure 2 The image shows a scanning electron microscope image of the porous adsorbent material prepared in Example 1 at high magnification (10500x).

[0028] Figure 3 The acid stability test results are for the porous adsorption materials for treating acidic mine wastewater prepared in Examples 1-3 and Comparative Examples 1-2.

[0029] Figure 4 The results show the adsorption performance test results of the porous adsorbent materials for treating acidic mine wastewater prepared in Examples 1-3 and Comparative Examples 1-3. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0032] In the following embodiments, the scanning electron microscope images of the porous adsorbent material for treating acidic mine wastewater are as follows: Figure 1 and Figure 2Unless otherwise specified, all methods are conventional. Unless otherwise specified, all materials used in the following examples are new materials purchased from the market. Specifically, the sodium bentonite is commercially available purified sodium bentonite with a montmorillonite content ≥90% and a particle size of 200 mesh; the urea, citric acid, and starch are all analytical grade with a purity ≥99%; the L-cysteine ​​is biological grade with a purity ≥99%; the cellulose is microcrystalline cellulose with a purity ≥99% and a particle size of 50 μm; the GPTMS, DMC, and DMA are all chemically pure with a purity ≥98%, and are colorless, transparent liquids; the PVP is K30 grade with an average molecular weight of 40,000, and is a white powder; the NaCl is analytical grade with a purity ≥99.5%, and is a white crystalline powder; the PEG is PEG-4000, analytical grade, and is a white waxy solid; the ammonium persulfate is analytical grade with a purity ≥98%, and is a white crystalline powder; the dialysis bag used is made of regenerated cellulose material with a molecular weight cutoff of 1000. Da; The high-pressure hydrothermal reactor used was a 500 mL polytetrafluoroethylene-lined high-pressure hydrothermal reactor, with a reaction temperature of 200℃ and a corresponding saturated vapor pressure of 1.55 MPa.

[0033] Example 1: This example provides a porous adsorbent material for treating acidic mine wastewater. The porous adsorbent material comprises the following raw materials in parts by weight: 55 parts modified bentonite, 10 parts citric acid, 1 part L-cysteine, 5 parts GPTMS, 10 parts DMC, 5 parts DMA, 2.5 parts PVP, and 0.5 parts ammonium persulfate.

[0034] The modified bentonite comprises the following raw materials in parts by weight: 65 parts sodium-based bentonite and 8 parts urea.

[0035] The preparation method of the modified bentonite includes the following steps:

[0036] S1: Weigh 65 parts of sodium bentonite and disperse them in deionized water at a mass-to-volume ratio of 1 g: 15 mL. Stir at 800 rpm for 1 hour at room temperature to obtain a suspension.

[0037] S2: Place the suspension at 70℃ and slowly add 8 parts of urea while stirring. After reacting at a constant temperature for 4 hours, centrifuge at 8000 rpm for 15 minutes, collect the precipitate, and wash it 2-3 times with 60℃ deionized water to obtain the precipitate product.

[0038] S3: The precipitate was dried at 60°C for 12 hours, ground, and then passed through a 200-mesh sieve to obtain modified bentonite.

[0039] This invention also provides a method for preparing porous adsorbent materials for treating acidic mine wastewater, specifically including the following steps:

[0040] Step 1: Weigh 55 parts of modified bentonite and disperse them in 1 mol / L hydrochloric acid solution at a mass-volume ratio of 1 g: 15 mL. Stir and react at 60℃ for 6 hours. Centrifuge at 8000 rpm for 15 minutes to obtain a precipitate. Wash the precipitate with deionized water until neutral and then redisperse it in deionized water to obtain a bentonite nanosheet colloidal suspension.

[0041] Step 2: Weigh 10 parts of citric acid and 1 part of L-cysteine, dissolve them in deionized water at a mass-volume ratio of 1 g: 20 mL, mix well to obtain a mixed solution, transfer the mixed solution to a high-pressure hydrothermal reactor, react at 200℃ for 4 hours, cool naturally to room temperature, and dialyze for 48 hours using a dialysis bag with a molecular weight cutoff of 1000 Da to obtain an S-CDs aqueous solution;

[0042] Step 3: At room temperature and 500 rpm, the S-CDs aqueous solution was slowly added dropwise to the bentonite nanosheet colloidal suspension. After stirring for 1 hour, 5 parts of GPTMS were added dropwise, and stirring was continued for 2 hours. After standing for 12 hours, the nascent hybrid gel was obtained.

[0043] Step 4: Under nitrogen protection, add 10 parts DMC, 5 parts DMA, 2.5 parts PVP and 0.5 parts ammonium persulfate to the nascent hybrid gel in sequence, place it at 60°C and carry out in-situ free radical polymerization reaction for 4 hours, cool to room temperature to obtain crude adsorbent material.

[0044] Step 5: Wash the crude adsorbent material with deionized water until neutral, then wash it three times with anhydrous ethanol to obtain neutral adsorbent material. Dry it at 60°C for 12 hours, pulverize it and pass it through a 100-mesh sieve to obtain porous adsorbent material for treating acidic mine wastewater.

[0045] Example 2: This example provides a porous adsorbent material for treating acidic mine wastewater. The porous adsorbent material comprises the following raw materials in parts by weight: 65 parts modified bentonite, 15 parts starch, 2.5 parts L-cysteine, 13 parts GPTMS, 23 parts DMC, 13 parts DMA, 6.5 parts NaCl, and 1.3 parts ammonium persulfate.

[0046] The modified bentonite comprises the following raw materials in parts by weight: 77 parts sodium-based bentonite and 10 parts urea.

[0047] The preparation method of the modified bentonite includes the following steps:

[0048] S1: Weigh 77 parts of sodium-based bentonite and disperse it in deionized water at a mass-to-volume ratio of 1 g: 15 mL. Stir at 800 rpm for 1 hour at room temperature to obtain a suspension.

[0049] S2: Place the suspension at 70°C and slowly add 10 parts of urea while stirring. After reacting at a constant temperature for 4 hours, centrifuge at 8000 rpm for 15 minutes, collect the precipitate, and wash it 2-3 times with 60°C deionized water to obtain the precipitate product.

[0050] S3: The precipitate was dried at 60°C for 12 hours, ground, and then passed through a 200-mesh sieve to obtain modified bentonite.

[0051] This invention also provides a method for preparing porous adsorbent materials for treating acidic mine wastewater, specifically including the following steps:

[0052] Step 1: Weigh 65 parts of modified bentonite and disperse them in 1 mol / L hydrochloric acid solution at a mass-volume ratio of 1 g: 15 mL. Stir and react at 60℃ for 6 hours. Centrifuge at 8000 rpm for 15 minutes to obtain filter cake. Wash the filter cake with deionized water until neutral and then redisperse it in deionized water to obtain bentonite nanosheet colloidal suspension.

[0053] Step 2: Weigh 15 parts of starch and 2.5 parts of L-cysteine, dissolve them in deionized water at a mass-volume ratio of 1 g: 20 mL, mix well to obtain a mixed solution, transfer the mixed solution to a high-pressure hydrothermal reactor, react at 200℃ for 4 hours, cool naturally to room temperature, and dialyze for 48 hours using a dialysis bag with a molecular weight cutoff of 1000 Da to obtain an S-CDs aqueous solution;

[0054] Step 3: At room temperature and 500 rpm, the S-CDs aqueous solution was slowly added dropwise to the bentonite nanosheet colloidal suspension. After stirring for 1 hour, 13 parts of GPTMS were added dropwise, and stirring was continued for 2 hours. After standing for 12 hours, the nascent hybrid gel was obtained.

[0055] Step 4: Under nitrogen protection, add 23 parts DMC, 13 parts DMA, 6.5 parts NaCl, and 1.3 parts ammonium persulfate to the nascent hybrid gel in sequence, place it at 60°C, and carry out in-situ free radical polymerization reaction for 4 hours. Cool to room temperature to obtain crude adsorbent material.

[0056] Step 5: Wash the crude adsorbent material with deionized water until neutral, then wash it three times with 100 mL of anhydrous ethanol to obtain neutral adsorbent material. Dry it at 60℃ for 12 hours, pulverize it and pass it through a 100-mesh sieve to obtain porous adsorbent material for treating acidic mine wastewater.

[0057] Example 3: This example provides a porous adsorbent material for treating acidic mine wastewater. The porous adsorbent material comprises the following raw materials in parts by weight: 80 parts modified bentonite, 20 parts cellulose, 4 parts L-cysteine, 21 parts GPTMS, 35 parts DMC, 21 parts DMA, 10.5 parts PEG, and 2.1 parts ammonium persulfate.

[0058] The modified bentonite comprises the following raw materials in parts by weight: 90 parts sodium-based bentonite and 12 parts urea.

[0059] The preparation method of the modified bentonite includes the following steps:

[0060] S1: Weigh 90 parts of sodium-based bentonite and disperse it in deionized water at a mass-to-volume ratio of 1 g: 15 mL. Stir at 800 rpm for 1 hour at room temperature to obtain a suspension.

[0061] S2: Place the suspension at 70°C and slowly add 12 parts of urea while stirring. After reacting at a constant temperature for 4 hours, centrifuge at 8000 rpm for 15 minutes, collect the precipitate, and wash it 2-3 times with 60°C deionized water to obtain the precipitate product.

[0062] S3: The precipitate was dried at 60°C for 12 hours, ground, and then passed through a 200-mesh sieve to obtain modified bentonite.

[0063] This invention also provides a method for preparing porous adsorbent materials for treating acidic mine wastewater, specifically including the following steps:

[0064] Step 1: Weigh 80 parts of modified bentonite and disperse it in 1 mol / L hydrochloric acid solution at a mass-volume ratio of 1 g: 15 mL. Stir and react at 60℃ for 6 hours. Centrifuge at 8000 rpm for 15 minutes to obtain filter cake. Wash the filter cake with deionized water until neutral and then redisperse it in deionized water to obtain bentonite nanosheet colloidal suspension.

[0065] Step 2: Weigh 20 parts of cellulose and 4 parts of L-cysteine, dissolve them in deionized water at a mass-volume ratio of 1 g: 17 mL, mix them evenly to obtain a mixed solution, transfer the mixed solution to a high-pressure hydrothermal reactor, react at 200℃ for 4 hours, cool naturally to room temperature, and dialyze for 48 hours using a dialysis bag with a molecular weight cutoff of 1000 Da to obtain an S-CDs aqueous solution;

[0066] Step 3: At room temperature and 500 rpm, the S-CDs aqueous solution was slowly added dropwise to the bentonite nanosheet colloidal suspension. After stirring for 1 hour, 21 parts of GPTMS were added dropwise, and stirring was continued for 2 hours. After standing for 12 hours, the nascent hybrid gel was obtained.

[0067] Step 4: Under nitrogen protection, add 35 parts of DMC, 21 parts of DMA, 10.5 parts of PEG and 2.1 parts of ammonium persulfate to the nascent hybrid gel in sequence, place it at 60°C and carry out in-situ free radical polymerization reaction for 4 hours, cool to room temperature to obtain crude adsorbent material;

[0068] Step 5: Wash the crude adsorbent material with deionized water until neutral, then wash it three times with 100 mL of anhydrous ethanol to obtain neutral adsorbent material. Dry it at 60℃ for 12 hours, pulverize it and pass it through a 100-mesh sieve to obtain porous adsorbent material for treating acidic mine wastewater.

[0069] The difference between Comparative Example 1 and Example 1 is that no S-CDs aqueous solution and GPTMS were added; the rest of the parts are the same as Example 1.

[0070] The difference between Comparative Example 2 and Example 1 is that no modified bentonite was prepared; instead, an equal amount of sodium-based bentonite was used directly. The rest of the process was the same as in Example 1.

[0071] Comparative Example 3 uses a commercially available adsorbent—granular activated carbon (GAC)—as a comparison and does not involve the preparation process of the material described in this invention.

[0072] Acid stability test

[0073] Accurately weigh 100 mg of the porous adsorbent materials prepared in Examples 1-3 and Comparative Examples 1-2, and place them in separate 150 mL Erlenmeyer flasks. Add 100 mL of sulfuric acid solution with pH 2.0 to each flask, seal the flasks tightly, and place them in a constant-temperature shaker at 25°C and 150 rpm for 24 hours. After shaking, immediately aspirate the supernatant and filter it through a 0.45 μm filter membrane to obtain a clear filtrate. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to determine the aluminum ion concentration (Al) in each filtrate. 3 + The concentration of ) is shown in the results. Figure 3 The aluminum leaching amount is calculated using the formula ω = (C × V) / m, where ω is the amount of aluminum leached from the material and C is the amount of Al in the filtrate. 3+ Concentration, V is the volume of the soaking solution, and m is the mass of the material.

[0074] Adsorption performance test

[0075] Prepare simulated acidic mine wastewater with a pH of 3.0, containing Cu. 2+ (50 mg / L), Pb 2+ (50 mg / L), Zn 2+ (50 mg / L) and SO4 2-(500 mg / L). 100 mL of the acidic mine wastewater was placed in 150 mL Erlenmeyer flasks, and 100 mg of the porous adsorbent materials prepared in Examples 1-3 and Comparative Examples 1-2, and the commercially available granular activated carbon in Comparative Example 3 were added respectively. The Erlenmeyer flasks were placed in a constant-temperature shaker and shaken at 25°C and 150 rpm for 120 minutes. After the set time, samples were taken, filtered through a 0.45 μm filter membrane, and the concentration of heavy metal ions in the filtrate was determined by ICP-OES, and SO4 was determined by ion chromatography (IC). 2- Concentration, results are shown in Figure 4 And according to the formula, the adsorption capacity q t =(C0-C e The adsorption performance is calculated as q × V / m, where q t Let C0 and C be the adsorption capacity at time t. e The initial and equilibrium concentrations of the ions to be measured are denoted as V, V is the volume of the solution, and m is the mass of the adsorbent material added.

[0076] Selective adsorption capacity test

[0077] In simulated acidic mine wastewater (Cu) at pH 3.0 2+ (50 mg / L), Pb 2+ (50 mg / L), Zn 2+ (50 mg / L) and SO4 2- Based on (500 mg / L), an additional high concentration of competing ion Ca was added. 2+ (200 mg / L) and Mg 2+ (200 mg / L) Prepare complex wastewater systems. Measure 100 mL of this complex wastewater system into 150 mL Erlenmeyer flasks, and add 100 mg of the porous adsorbent materials prepared in Examples 1-2 and Comparative Example 1, and the commercially available granular activated carbon in Comparative Example 3, respectively. Place the Erlenmeyer flasks in a constant-temperature shaker and shake for 120 minutes at 25°C and 150 rpm. After the set time, take samples, filter through a 0.45 μm filter membrane, and determine the concentration of each metal ion using ICP-OES and SO42- (ICP-OES) for further analysis. 2- Concentrations, results are shown in Table 1. Using formula K... d =(C0-C e ) / C e Calculate the distribution coefficient of each ion using ×V / m, and then apply K(A / B)=K d (A) / K d (B) Calculate the selectivity coefficient, where K d Let C0 and C be the distribution coefficients. e , where are the initial and equilibrium concentrations of the analyte, respectively; V is the solution volume; m is the adsorbent mass; and K(A / B) is the selectivity coefficient of analyte A relative to analyte B.

[0078] Table 1 Results of Selective Adsorption Capacity Test

[0079]

[0080] Results Analysis

[0081] Figure 3 The results showed that the porous adsorbents prepared in Examples 1-3 exhibited excellent acid stability, with aluminum leaching amounts all below 8 mg / g in sulfuric acid solution at pH 2.0. In contrast, Comparative Example 1, without the addition of S-CDs aqueous solution and GPTMS, showed an aluminum leaching amount of 28.5 mg / g, while Comparative Example 2, without modified bentonite, showed a high aluminum leaching amount of 68.7 mg / g. This indicates that the porous adsorbents prepared in Examples 1-3, through urea pre-intercalation and the construction of an organic-inorganic hybrid three-dimensional network structure, effectively inhibited the erosion of the bentonite framework by strong acid, significantly improving the acid stability of the porous adsorbents prepared in Examples 1-3.

[0082] Figure 4 The results showed that Example 1 was effective against Cu 2+ Pb 2+ and SO4 2- The adsorption capacities reached 49.5 mg / g, 48.8 mg / g, and 185.5 mg / g, respectively, and their adsorption performance was significantly better than all comparative examples. Comparative Example 1, without the addition of S-CDs aqueous solution and GPTMS, had an adsorption capacity less than 50% of that of Example 1, demonstrating that multi-mechanism synergistic adsorption is key to achieving efficient adsorption. Comparative Example 3 (commercially available granular activated carbon) showed adsorption capacity of less than 50% of that of Example 1 for SO42-. 2- The extremely low adsorption capacity highlights the unique advantage of the porous adsorption material in the simultaneous removal of anions and cations.

[0083] Table 1 shows the results of the porous adsorbent material prepared in Example 1 for Cu 2+ Relative to Ca 2+ Selectivity coefficient K(Cu) 2 + / Ca 2+ The value reached 125.5, significantly higher than that of Comparative Example 1 and Comparative Example 3. This indicates that the specific strong coordination of the -SH groups of S-CDs with heavy metals in the porous adsorbent materials prepared in Examples 1-2, and the strong complexation of the catechol groups in DMA, together endow the materials with excellent selective adsorption capacity.

[0084] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A porous adsorbent material for treating acidic mine wastewater, characterized in that, The porous adsorbent material comprises the following raw materials in parts by weight: 55-80 parts modified bentonite, 10-20 parts carbon source, 1-4 parts L-cysteine, 5-21 parts GPTMS, 10-35 parts DMC, 5-21 parts DMA, 2.5-10.5 parts porogen, and 0.5-2.1 parts ammonium persulfate; The modified bentonite comprises the following raw materials: sodium bentonite and urea, and the preparation method of the modified bentonite is as follows: S1: Weigh out sodium-based bentonite and disperse it in deionized water to obtain a suspension; S2: Weigh out urea and slowly add it to the suspension while stirring. Centrifuge and wash to obtain the precipitate. S3: Dry and grind the precipitate to obtain modified bentonite.

2. The porous adsorption material for treating acidic mine wastewater according to claim 1, characterized in that, The mass ratio of sodium bentonite to urea is 7-12:

1.

3. The porous adsorption material for treating acidic mine wastewater according to claim 1, characterized in that, The carbon source is selected from any one of citric acid, starch, and cellulose.

4. The porous adsorption material for treating acidic mine wastewater according to claim 1, characterized in that, The porogen is selected from any one of PVP, NaCl, and PEG.

5. A method for preparing a porous adsorbent material for treating acidic mine wastewater according to any one of claims 1-4, characterized in that, The specific preparation method is as follows: Step 1: Weigh the modified bentonite, disperse, centrifuge, wash, and redisperse to obtain a bentonite nanosheet colloidal suspension; Step 2: Weigh the carbon source and L-cysteine ​​and dissolve them to obtain a mixed solution. After high-pressure hydrothermal reaction and dialysis, obtain an aqueous solution of S-CDs. Step 3: Add S-CDs aqueous solution and GPTMS sequentially to bentonite nanosheet colloidal suspension and mix well to obtain primary hybrid gel; Step 4: Weigh DMC, DMA, pore-forming agent, and ammonium persulfate, and add them together to the primary hybrid gel to react and obtain crude adsorbent material; Step 5: After washing, drying and pulverizing the crude adsorbent material, a porous adsorbent material for treating acidic mine wastewater is obtained.

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