A carbon-silicon intercalated composite clay material for biogas slurry additive, preparation method and application thereof

Abstract

The present invention belongs to the field of new material technology and discloses a carbon-silicon intercalated composite clay material for biogas slurry additive, a preparation method and application thereof. The method comprises the following steps: (1) preparing a carbon-silicon material; (2) preparing a reaction solution A; (3) preparing a bentonite reaction solution B; (4) solution intercalation; (5) acidification reaction; (6) hydrothermal reaction; and (7) post-treatment to obtain a carbon-silicon intercalated composite clay material. The present invention is a carbon-silicon intercalated bentonite composite material that combines the advantages of a porous structure, a high cation exchange capacity, and abundant active groups of both carbon-based materials and clay materials, and a large number of surface adsorption sites. When added to biogas slurry, it can adsorb ammonium ions and promote the sedimentation and adsorption of phosphate on the material. It has a fixing effect on nitrogen and phosphorus nutrients in biogas slurry. In addition, when added to returned soil, it can simultaneously play a role in retaining nitrogen and phosphorus, and can also regulate soil pH and improve soil quality, achieving a one-dose dual-effect dual effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and in particular relates to a carbon-silicon intercalated composite clay material for biogas slurry additives, a preparation method and applications thereof. Background Art

[0002] In today's context of sustainable agricultural development, the resource utilization of agricultural waste has become a key research area. Biogas slurry, a byproduct of anaerobic digestion, is rich in nutrients such as nitrogen, phosphorus, and potassium, as well as a variety of organic substances, and is considered a potential high-quality organic fertilizer. Returning biogas slurry to farmland not only reduces the use of chemical fertilizers and saves costs, but also effectively treats agricultural waste, reduces environmental pollution, and improves soil quality.

[0003] However, during the actual biogas slurry return process, nitrogen and phosphorus nutrient losses are a significant problem. Ammonia volatilization, a major pathway for nitrogen loss in biogas slurry, accounts for approximately 80% of nitrogen losses, making it a key solution to nitrogen nutrient loss. During the biogas slurry storage phase, key methods to reduce ammonia generation and volatilization include chemical precipitation to recover nitrogen and phosphorus nutrients, membrane separation, mulching to reduce emissions, acidification, and material adsorption, while simultaneously achieving nutrient sequestration. During the biogas slurry return phase, targeted fertilization, soil improvement, adsorbent addition, microbial inoculation, and green manure cultivation are used to improve nutrient utilization, reduce losses, and protect the environment. Current research focuses on the development of biogas slurry additive materials, including biochar-based materials, humic acid-based materials, and biomass composting. Biochar, as a soil conditioner, when mixed with biogas slurry, can alter the bulk density, porosity, and aggregate structure of farmland soil, affecting its redox potential and CEC (composting efficiency), and has a moderating effect on soil salinization. At the same time, biochar has a high specific surface area and a developed pore structure, which can adsorb nitrogen and phosphorus nutrients and achieve nutrient recovery. Wei Qiufang and others from South China Agricultural University prepared a magnetic micro-nano biochar-zeolite composite material through a solvent thermal method to adsorb nutrients from biogas slurry and prepare solid biogas fertilizer. In the study of humic acid materials, the research team of the Chengdu Institute of Biology, Chinese Academy of Sciences, selected corn straw hydrolysis residue as raw material and KOH as an auxiliary agent. Under hydrothermal conditions, an artificial humification reaction occurred, and finally phosphoric acid was used for neutralization to prepare a humic acid-type water-soluble fertilizer. It has a similar chemical composition to natural humic acid and can promote the growth of Chinese cabbage.

[0004] The biogas slurry additive materials disclosed in scientific and patent literature so far generally have one or more shortcomings: ① the material preparation process is complex, energy-intensive, and costly; ② the raw materials are expensive and difficult to obtain; ③ the use process is demanding and complex, making it difficult to apply on a large scale.

[0005] The purpose of the present invention is to provide an auxiliary material that can be applied to a large number of scenarios of returning biogas slurry to farmland. Under suitable process conditions, this auxiliary material can be prepared in large quantities and can be applied to a variety of scenarios of returning biogas slurry to farmland. It has a high nitrogen and phosphorus nutrient retention effect and can effectively reduce nutrient loss during the process of returning biogas slurry to farmland. Summary of the Invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a carbon-silicon intercalated composite clay material for biogas slurry additive, a preparation method and an application thereof.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] A method for preparing a carbon-silicon intercalated composite clay material for a biogas slurry additive, the method comprising the following steps:

[0009] (1) Preparation of carbon silicon materials:

[0010] The collected vinasse waste and silicate tailings were mixed, crushed to a suitable particle size using ammonium polymethacrylate as a dispersant, passed through a 50-mesh sieve, and subjected to high-temperature cracking in a muffle furnace at 500°C under nitrogen atmosphere for 4 hours to obtain a gray-black solid powder a as a carbon silicon material, which was placed in a vacuum desiccator for later use;

[0011] (2) Preparation of reaction solution A:

[0012] Weigh the heat-activated carbon silicon material a, add 2 mol / L NaOH solution, and shake on a shaker at 180 rpm for 30 min to fully react to obtain reaction solution A; wherein the ratio of carbon silicon material a to NaOH solution is 8.0:30 g:ml;

[0013] (3) Preparation of bentonite reaction solution B:

[0014] Weigh sodium bentonite, add ultrapure water, shake, and thoroughly mix. Then, add 0.05 mol / L EDTA solution. Use a high-speed dispersing homogenizer to perform high-speed shearing for 30 minutes to obtain a suspension with uniform bentonite distribution, which is bentonite reaction solution B. The ratio of sodium bentonite: ultrapure water: EDTA solution (g:ml:ml) is 4.0:100:10.

[0015] (4) Solution intercalation:

[0016] Use a pipette to slowly add reaction solution A to the bentonite reaction solution B that is being sheared at high speed, add formamide, and continue to use a high-speed dispersing homogenizer to shear at high speed for 90 minutes to ensure that the reaction occurs fully and the intercalation is complete; wherein, the ratio of carbon silicon material a in the preparation of reaction solution A: sodium bentonite in the preparation of reaction solution B: formamide is 8.0:4.0:3 in g:g:ml;

[0017] (5) Acidification reaction:

[0018] Acidify the intercalated reaction solution with 2 mol / L hydrochloric acid solution and shake on a shaker at 180 rpm for 30 min.

[0019] (6) Hydrothermal reaction:

[0020] The acidified reaction solution was subjected to a hydrothermal reaction, firstly heated to 90°C at a rate of 15°C / min, and after thermal activation for 30 min, the temperature was raised to 120°C at the same rate and the hydrothermal reaction was carried out for 240 min.

[0021] (7) Post-processing:

[0022] After the hydrothermal reaction is completed, the mixture is allowed to stand at room temperature and the solution is centrifuged to leave a black precipitate. The precipitate is repeatedly washed by centrifugation with ultrapure water and anhydrous ethanol, a 3% mass concentration hydrogen peroxide solution is added, ultrasonic treatment is performed for 30 minutes, centrifugation is performed, ultrapure water and anhydrous ethanol are washed, the mixture is dried at 70°C, and ground through a 50-mesh sieve to obtain a gray-black solid powder, thereby obtaining a carbon-silicon intercalated composite clay material for biogas slurry additive.

[0023] Furthermore, in step (1), the collected wine lees waste and silicate tailings are mixed in a mass ratio of 4:1.

[0024] Furthermore, in step (3), the sodium bentonite is 400 mesh.

[0025] Furthermore, the reaction solution after acidification in step (6) is poured into a hydrothermal reactor lined with tetrafluoroethylene for hydrothermal reaction.

[0026] Application of the preparation method as described above in the preparation of biogas slurry additives.

[0027] The carbon-silicon intercalated composite clay material used as a biogas slurry additive is prepared by the preparation method described above.

[0028] The application of the carbon-silicon intercalated composite clay material as described above in the adsorption of ammonia nitrogen and phosphorus in biogas slurry.

[0029] The application of the carbon-silicon intercalated composite clay material in the adsorption of ammonium ions in biogas slurry.

[0030] The application of the carbon-silicon intercalated composite clay material as described above in promoting the precipitation adsorption of phosphate.

[0031] The carbon-silicon intercalated composite clay material as described above is used to fix nitrogen and phosphorus nutrients in biogas slurry.

[0032] The advantages and effects achieved by the present invention are:

[0033] 1. The present invention is a carbon-silicon intercalated bentonite composite material, which has the advantages of both carbon-based materials and clay materials, such as porous structure, high cation exchange capacity, rich active groups, and a large number of surface adsorption sites. When added to biogas slurry, it can adsorb ammonium ions and promote the sedimentation and adsorption of phosphate on the material. It has a fixation effect on nitrogen and phosphorus nutrients in the biogas slurry. In addition, when added to the returned soil, it can also play a role in retaining nitrogen and phosphorus, and can also adjust the soil pH and improve the soil quality, achieving a dual-effect one-dose.

[0034] 2. The raw materials of the present invention are agricultural waste and common mineral waste. Compared with existing biogas slurry additive products, it has the following advantages: simple preparation process, low cost, large-scale preparation, and good nutrient retention and slow-release performance.

[0035] 3. In the present invention, ammonium polymethacrylate is used as a dispersant to ensure sufficient dispersion and mixing of carbon silicon through electrostatic repulsion and steric hindrance effects, thereby avoiding agglomeration and increasing the number of carboxylic acid groups on the surface of the carbon silicon material.

[0036] 4. The small molecule substance used in this invention - EDTA (ethylenediaminetetraacetic acid) deeply removes the interlayer metal ion Na by chelation. + etc., expand the interlayer spacing and assist in intercalation; formamide, as a strong polar solvent molecule, significantly expands the interlayer spacing and promotes the completion of intercalation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the interlayer structure of bentonite in the present invention;

[0038] Figure 2 is a microstructure diagram of the carbon silicon material in the present invention;

[0039] Figure 3 This is a surface structure diagram of the composite material after intercalation in the present invention;

[0040] Figure 4 This is the Fourier infrared spectrum of the carbon-silicon intercalated composite clay material of the present invention;

[0041] Figure 5 The XRD diffraction pattern of the carbon-silicon intercalated composite clay material of the present invention is:

[0042] Figure 6 This is the energy spectrum of the main elements present in the carbon-silicon intercalated composite clay material of the present invention;

[0043] Figure 7 This is a graph showing the valence state and content of carbon in the carbon-silicon intercalated composite clay material of the present invention;

[0044] Figure 8This is a graph showing the N2-BET adsorption and desorption curves of the carbon-silicon intercalated composite clay material of the present invention;

[0045] Figure 9 This is the BJH pore size distribution diagram of the carbon-silicon intercalated composite clay material of the present invention;

[0046] Figure 10 This is a diagram demonstrating the ammonia nitrogen adsorption performance of the carbon-silicon intercalated composite clay material of the present invention;

[0047] Figure 11 This is a graph showing the adsorption kinetics of ammonia nitrogen adsorption by the carbon-silicon intercalated composite clay material of the present invention;

[0048] Figure 12 This is a graph demonstrating the desorption ability of the carbon-silicon intercalated composite clay material of the present invention in low and medium concentration ammonia nitrogen solutions;

[0049] Figure 13 This is a diagram demonstrating the desorption ability of the carbon-silicon intercalated composite clay material of the present invention in medium and high concentration ammonia nitrogen solutions. DETAILED DESCRIPTION

[0050] The present invention will be further described below with reference to the embodiments. The following embodiments are descriptive rather than restrictive, and the scope of protection of the present invention cannot be limited by the following embodiments.

[0051] The various experimental operations involved in the specific embodiments are all routine techniques in the field. For parts not specifically annotated in this document, ordinary technicians in this field can refer to various commonly used reference books, scientific literature or related instructions, manuals, etc. before the filing date of this invention to implement them.

[0052] A method for preparing a carbon-silicon intercalated composite clay material for a biogas slurry additive, the method comprising the following steps:

[0053] (1) Preparation of carbon silicon materials:

[0054] The collected vinasse waste and silicate tailings were mixed, crushed to a suitable particle size using ammonium polymethacrylate as a dispersant, passed through a 50-mesh sieve, and subjected to high-temperature cracking in a muffle furnace at 500°C under nitrogen atmosphere for 4 hours to obtain a gray-black solid powder a as a carbon silicon material, which was placed in a vacuum desiccator for later use;

[0055] (2) Preparation of reaction solution A:

[0056] Weigh the heat-activated carbon silicon material a, add 2 mol / L NaOH solution, and shake on a shaker at 180 rpm for 30 min to fully react to obtain reaction solution A; wherein the ratio of carbon silicon material a to NaOH solution is 8.0:30 g:ml;

[0057] (3) Preparation of bentonite reaction solution B:

[0058] Weigh sodium bentonite, add ultrapure water, shake, and thoroughly mix. Then, add 0.05 mol / L EDTA solution. Use a high-speed dispersing homogenizer to perform high-speed shearing for 30 minutes to obtain a suspension with uniform bentonite distribution, which is bentonite reaction solution B. The ratio of sodium bentonite: ultrapure water: EDTA solution (g:ml:ml) is 4.0:100:10.

[0059] (4) Solution intercalation:

[0060] Use a pipette to slowly add reaction solution A to the bentonite reaction solution B that is being sheared at high speed, add formamide, and continue to use a high-speed dispersing homogenizer to shear at high speed for 90 minutes to ensure that the reaction occurs fully and the intercalation is complete; wherein, the ratio of carbon silicon material a in the preparation of reaction solution A: sodium bentonite in the preparation of reaction solution B: formamide is 8.0:4.0:3 in g:g:ml;

[0061] (5) Acidification reaction:

[0062] Acidify the intercalated reaction solution with 2 mol / L hydrochloric acid solution and shake on a shaker at 180 rpm for 30 min.

[0063] (6) Hydrothermal reaction:

[0064] The acidified reaction solution was subjected to a hydrothermal reaction, firstly heated to 90°C at a rate of 15°C / min, and after thermal activation for 30 min, the temperature was raised to 120°C at the same rate and the hydrothermal reaction was carried out for 240 min.

[0065] (7) Post-processing:

[0066] After the hydrothermal reaction is completed, the mixture is allowed to stand at room temperature and the solution is centrifuged to leave a black precipitate. The precipitate is repeatedly washed by centrifugation with ultrapure water and anhydrous ethanol, a 3% mass concentration hydrogen peroxide solution is added, ultrasonic treatment is performed for 30 minutes, centrifugation is performed, ultrapure water and anhydrous ethanol are washed, the mixture is dried at 70°C, and ground through a 50-mesh sieve to obtain a gray-black solid powder, thereby obtaining a carbon-silicon intercalated composite clay material for biogas slurry additive.

[0067] Preferably, in step (1), the collected wine lees waste and silicate tailings are mixed in a mass ratio of 4:1.

[0068] Preferably, the sodium bentonite in step (3) is 400 mesh.

[0069] Preferably, the reaction solution after acidification in step (6) is poured into a hydrothermal reactor lined with tetrafluoroethylene for hydrothermal reaction.

[0070] Application of the preparation method as described above in the preparation of biogas slurry additives.

[0071] The carbon-silicon intercalated composite clay material used as a biogas slurry additive is prepared by the preparation method described above.

[0072] The application of the carbon-silicon intercalated composite clay material as described above in the adsorption of ammonia nitrogen and phosphorus in biogas slurry.

[0073] The application of the carbon-silicon intercalated composite clay material in the adsorption of ammonium ions in biogas slurry.

[0074] The application of the carbon-silicon intercalated composite clay material as described above in promoting the precipitation adsorption of phosphate.

[0075] The carbon-silicon intercalated composite clay material as described above is used to fix nitrogen and phosphorus nutrients in biogas slurry.

[0076] Specifically, the relevant preparation and testing are as follows:

[0077] 1. Preparation method of auxiliary materials:

[0078] 1. Preparation of carbon silicon materials:

[0079] The collected vinasse waste and silicate tailings were mixed in a mass ratio of 4:1, and an appropriate amount of ammonium polymethacrylate was used as a dispersant. The mixture was crushed to a suitable particle size, passed through a 50-mesh sieve, and subjected to high-temperature cracking in a muffle furnace at 500°C under nitrogen atmosphere for 4 hours to obtain a gray-black solid powder a as a carbon silicon material, which was placed in a vacuum dryer for later use.

[0080] 2. Preparation of reaction solution A:

[0081] 8.0 g of heat-activated carbon silicon material a was weighed, 30 ml of 2 mol / L NaOH solution was added, and the mixture was shaken on a shaker at 180 rpm for 30 min to fully react to obtain reaction solution A.

[0082] 3. Preparation of bentonite reaction solution B:

[0083] Weigh 4.0 g of 400-mesh sodium bentonite, add 100 ml of ultrapure water, shake, and thoroughly mix. Then, add 10 ml of 0.05 mol / L EDTA solution. Use a high-speed dispersing homogenizer to perform high-speed shearing for 30 min to obtain a suspension in which the bentonite is evenly distributed, which is bentonite reaction solution B.

[0084] 4. Solution intercalation:

[0085] Use a pipette to slowly add reaction solution A to the bentonite reaction solution B that is being sheared at high speed (i.e., shear for 30 minutes to form reaction solution B, then add reaction solution A and continue high-speed shearing). Add 3 ml of formamide and continue to use a high-speed disperser homogenizer to shear at high speed for 90 minutes to ensure that the reaction occurs fully and the intercalation is complete.

[0086] 5. Acidification reaction:

[0087] The reaction solution after intercalation was acidified with 2 mol / L hydrochloric acid solution and shaken on a shaker at 180 rpm for 30 min.

[0088] 6. Hydrothermal reaction:

[0089] The acidified reaction solution was poured into a hydrothermal reactor lined with tetrafluoroethylene for hydrothermal reaction. The temperature was first raised to 90°C at a rate of 15°C / min. After thermal activation for 30 minutes, the temperature was raised to 120°C at the same rate for hydrothermal reaction for 240 minutes.

[0090] 7. Post-processing:

[0091] After the hydrothermal reaction is completed, the mixture is allowed to cool to room temperature. The reactor is opened, the solution is poured out, and centrifugation is performed to leave a black precipitate. This is then washed repeatedly by centrifugation with ultrapure water and anhydrous ethanol. An appropriate amount of 3% hydrogen peroxide solution is added. Hydrogen peroxide has more surface-active polar groups, making it easier to disperse and less likely to precipitate. The mixture is then ultrasonically treated for 30 minutes, centrifuged, washed with ultrapure water and anhydrous ethanol, dried at 70°C, and ground through a 50-mesh sieve to obtain a gray-black solid powder. This is the prepared carbon-silicon intercalated composite sodium bentonite material, a carbon-silicon intercalated composite clay material for biogas slurry additives.

[0092] 2. Verification of additive material properties

[0093] The carbon-silicon intercalated sodium bentonite composite material of the present invention is a biogas slurry additive material prepared by intercalating sodium-based bentonite with carbon-silicon material obtained by burning waste lees biomass and waste silicate and carbonate tailings. The main components of the composite material are C19%, H2%, O50%, N2%, P3%, S1%, Si17%, Al6%, with a pH of 3.70 and a density of 2.515 g / cm 3 , with a specific surface area of ​​130.7m 2 / g.

[0094] 1. The microstructure of the additive material under the scanning electron microscope is as follows: Figure 1 、 Figure 2 and Figure 3 shown.

[0095] Scanning electron microscopy revealed that at a 500nm scale, the sodium bentonite in the additive material transformed from its original tightly packed interlamellar structure to an irregular, curled-up, stacked lamellae structure. Alkaline hydrolysis of the sodium bentonite lamellar structure increased the interlamellar spacing, releasing interlamellar metal ions. High-speed shear forces exposed the carbon chain structure of the carbon-silicon material, which then extended and intercalated into the sodium bentonite via small molecules. At a 200nm scale, intercalation of the carbon-silicon material into the sodium bentonite lamellae was observed, with the sodium bentonite lamellae stacked on the surface of the carbon-silicon material, demonstrating the occurrence of intercalation and the successful intercalation of carbon-silicon into the bentonite structure. The high-molecular carbon-silicon structure combined with the layered silicate structure of the intercalated bentonite formed a new composite material.

[0096] 2. Fourier infrared spectrum of auxiliary materials Figure 4 shown.

[0097] from Figure 4 As can be seen, 3432.78cm -1 Corresponding to OH stretching vibration, 1636.20 cm -1 Corresponding to C=C, C=O stretching vibration and OH bending vibration, these absorption peaks correspond to the carbon material structure in the sample, 1047.87cm -1 Corresponding to the antisymmetric stretching vibration of Si-O-Si, 796.81 cm -1 Corresponding to the symmetric stretching vibration of Si-O-Si, 469.02 cm -1 Corresponding to the bending vibration of Si-O-Si, these absorption peaks correspond to the silicate structure in the sample.

[0098] 3. The XRD diffraction pattern of the auxiliary material is as follows: Figure 5 shown.

[0099] from Figure 5 It can be seen that by comparing the XRD diffraction patterns of the auxiliary materials and the standard material pattern cards, it is found that the crystal structures present in the auxiliary materials are silica and aluminosilicate, etc. Silica and aluminosilicate crystals serve as the crystal skeleton of the auxiliary materials, supporting the three-dimensional structure of the entire material and providing adsorption reaction centers and binding sites for the auxiliary materials to adsorb ammonia nitrogen and phosphorus.

[0100] 4. XPS results of additive materials are as follows Figure 6 、 Figure 7 shown. Figure 6 The energy spectrum of the main elements in the composite material is summarized in Table 1. Figure 7 It can be found that the valence state of C element is C1s, including three chemical bonds: CC / CH, CO and CO3 2-, accounting for 56.15%, 39.09% and 4.76% respectively.

[0101] Table 1 Main element contents of composite additive materials

[0102]

[0103] The element atomic content results of the composite material show that the component contents of the carbon skeleton and silicate skeleton of the composite material are basically the same, and the two structures are interlaced and compounded together to form a composite structure of carbon-silicon material intercalated with sodium-based bentonite.

[0104] 5. Specific surface area and porosity of additive materials:

[0105] The specific surface area of ​​the composite material is 130.7370m 2 / g (BET method), the single-point adsorption total pore volume is 0.248092 cm³ / g, the t-Plot micropore volume is 0.017166 cm³ / g, and the adsorption average pore diameter (BJH method) is 10.5484 cm³ / g, as shown in Tables 2, 3 and 4 below.

[0106] Table 2 Specific surface area test results of composite additive materials

[0107]

[0108] Table 3 Pore volume test results of composite additive materials

[0109]

[0110] Table 4 Pore size test results of composite additive materials

[0111]

[0112] Figure 8 and Figure 9 The N2-BET adsorption and desorption curves of the auxiliary material, as well as the BJH pore size distribution diagram. Figure 8 and Figure 9 It can be seen that the adsorption and desorption isotherms of the additive material do not overlap, forming an H3-type hysteresis loop, which shows that the pore structure of the material is a flat slit structure, cracks and wedge-shaped structure. This is due to the slit-shaped pores formed by the stacking of flaky particles of the clay component in the material.

[0113] 3. Application Verification

[0114] The auxiliary material of the present invention is mainly used in the process of returning biogas slurry to farmland. By compounding biogas slurry with the auxiliary material and adjusting the application ratio, the absorption, retention and slow-release effects of the auxiliary material on nutrients in the biogas slurry are improved, thereby reducing nutrient loss and non-point source pollution caused by returning biogas slurry to farmland.

[0115] The raw materials for this auxiliary material are waste brewing lees, silicate and carbonate tailings, and sodium bentonite. Brewing lees are rich in cellulose and lignin, and the non-metallic tailings used are mainly composed of silicon dioxide, silicates, and carbonate compounds. The carbon silicon material is prepared by brewing lees and non-metallic tailings. The silicate builds the crystal skeleton, and the cellulose and other biomass in the brewing lees are pyrolyzed to form carbon chain macromolecules for filling. Finally, it is compounded with sodium bentonite using a high-speed shear-solution intercalation-hydrothermal synthesis method to form a composite material, which is the auxiliary material. Under the action of small molecule formamide, high-speed shear force, and EDTA reagent, the carbon molecular chains in the carbon silicon material are easily intercalated into the enlarged lamellar interlayer structure of the bentonite, thereby realizing the preparation of carbon silicon intercalated bentonite composite materials.

[0116] Based on the adsorption performance of the auxiliary material for ammonia nitrogen and phosphorus in the solution, the nutrient retention effect of the auxiliary material in the process of returning to the field is verified.

[0117] Ammonia nitrogen and phosphate adsorption properties of composite materials:

[0118] For experimental verification of composite materials:

[0119] In view of the ammonia nitrogen adsorption performance of the materials, a total of eight materials were selected, including corn cob biochar, corn straw biochar, wheat straw biochar, coconut shell charcoal, bamboo biochar, carbon silicon material, sodium bentonite and calcium bentonite, which are common in the market. The carbon silicon material and sodium bentonite with the best adsorption performance were compositely modified and the adsorption performance was studied.

[0120] By comparing the nitrogen and phosphorus adsorption properties of eight screened original materials and three composite modified materials, namely corn straw charcoal-sodium bentonite, wheat straw charcoal-sodium bentonite (these three materials use the same modification method, which is the method used in the present invention) and carbon silicon material-sodium bentonite, that is, the carbon-silicon intercalated composite clay material of the present invention, an appropriate amount of adsorption material was added to a 1000 mg / L ammonium chloride solution, and after reacting for 24 hours, the residual ammonium radical concentration of the solution was determined by the Nessler reagent colorimetric method (GB7479-87), thereby obtaining the adsorption capacity of the material. It was finally determined that the carbon silicon material and sodium bentonite were selected for intercalation compounding, and the composite material obtained after composite modification had the best nitrogen and phosphorus adsorption performance, such as Figure 10As shown, the ammonia nitrogen adsorption performance is 7.56 mg / g, which is 27% higher than the 5.94 mg / g of carbon silicon material; the phosphorus adsorption performance is 4.64 mg / g, which is 70% higher than the 2.73 mg / g of carbon silicon material. Among the three composite modified materials, the ammonia nitrogen adsorption capacity of carbon silicon material-sodium bentonite is 7.56 mg / g, corn straw charcoal-sodium bentonite is 6.31 mg / g, and wheat straw charcoal-sodium bentonite is only 4.47 mg / g. In terms of phosphorus adsorption, the adsorption capacity of carbon silicon material-sodium bentonite of 4.64 mg / g is significantly higher than that of corn straw charcoal-sodium bentonite of 2.03 mg / g and wheat straw charcoal-sodium bentonite of 2.11 mg / g.

[0121] Among them, the specific preparation method of the corn straw charcoal-sodium bentonite and wheat straw charcoal-sodium bentonite is: select commercially available corn straw biochar / wheat straw biochar prepared by pyrolysis at 500°C in a muffle furnace, pass through a 50-mesh sieve, and the subsequent preparation method and addition ratio are consistent with the preparation method of the carbon-silicon intercalated composite clay material of the present invention.

[0122] The adsorption kinetics of the composite material of the present invention, namely the carbon-silicon intercalated composite clay material, for ammonia nitrogen adsorption is as follows: Figure 11 As shown, from Figure 11 It can be seen that the adsorption kinetics equation of the composite material fits well in the pseudo-second-order equation, indicating that there are two processes in the adsorption process, physical adsorption and chemical adsorption, and chemical adsorption is dominant.

[0123] The composite's ammonia nitrogen retention performance was investigated through adsorption experiments and desorption experiments at different concentrations (selecting materials that were adequately adsorbed at various initial ammonium chloride concentrations and measuring the ammonium concentration in the solution over time). All ammonia nitrogen concentration determination methods used in this paper were Nessler's reagent colorimetric methods, a commonly used and recognized method for determining ammonia nitrogen concentration in solutions.

[0124] The results are as follows Figure 12 and Figure 13As shown in the figure, the experimental results of ammonia nitrogen desorption at different initial concentrations found that: as the initial concentration increases, the diffusion power of ammonia nitrogen into the material increases due to the concentration difference, which increases the adsorption amount and also easily causes the accumulation of ammonia nitrogen around the material. The ammonia nitrogen desorption amount of this composite material at three initial concentrations of low, medium and high (low concentration: 10mg / L, 20mg / L, 30mg / L, 40mg / L, medium concentration: 50mg / L, 100mg / L, high concentration: 150mg / L, 200mg / L, 250mg / L) increases with the increase of ammonia nitrogen concentration, but is relatively stable overall. At low concentrations, the desorption amount at 10mg / L is 0.19mg / g, which is 0.24mg / g higher than 0.43mg / g at 40mg / L, while at 250mg / The desorption amount at 50 mg / L was 0.72 mg / g, which was only increased by 0.23 mg / g compared with 0.49 mg / g at 50 mg / L. This shows that at low concentrations, the increase in ammonia nitrogen concentration has a greater impact on the desorption amount of this material, but with the increase of ammonia nitrogen concentration, the increase in the desorption amount of this material slows down, indicating that the material of the present invention has the ability to release ammonium ions when the external ammonia nitrogen concentration is low, and effectively retain ammonium ions when the external ammonia nitrogen concentration is high, thereby ensuring the stable release of ammonium ions, indicating that this material has the effect of ammonia nitrogen nutrient adsorption-retention-slow release.

[0125] The original material selected for the modification test is a commercially available biochar product, which can be used as an example of a product on the market. The material of the present invention has higher ammonia nitrogen adsorption performance and phosphorus adsorption performance than these products. At the same time, due to the composite structure of carbon-silicon intercalated bentonite, the ammonia nitrogen nutrient can be adsorbed by the cation exchange capacity of the bentonite, and then combined with the inner carbon-silicon structure. The ability of the bentonite surface to easily exchange ions with the outside world can achieve the effect of slow release of ammonia nitrogen nutrients.

[0126] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments.

Claims

1. A method for preparing a carbon-silicon intercalated composite clay material for biogas slurry additive, characterized by: The method comprises the following steps: (1) Preparation of carbon silicon materials: The collected vinasse waste and silicate tailings were mixed, crushed to a suitable particle size using ammonium polymethacrylate as a dispersant, passed through a 50-mesh sieve, and subjected to high-temperature cracking in a muffle furnace at 500°C under nitrogen atmosphere for 4 hours to obtain a gray-black solid powder a as a carbon silicon material, which was placed in a vacuum desiccator for later use; (2) Preparation of reaction solution A: Weigh the heat-activated carbon silicon material a, add 2 mol / L NaOH solution, and shake on a shaker at 180 rpm for 30 min to fully react to obtain reaction solution A; wherein the ratio of carbon silicon material a to NaOH solution is 8.0:30 g:ml; (3) Preparation of bentonite reaction solution B: Weigh sodium bentonite, add ultrapure water, shake, and thoroughly mix. Then, add 0.05 mol / L EDTA solution. Use a high-speed dispersing homogenizer to perform high-speed shearing for 30 minutes to obtain a suspension with uniform bentonite distribution, which is bentonite reaction solution B. The ratio of sodium bentonite: ultrapure water: EDTA solution (g:ml:ml) is 4.0:100:

10. (4) Solution intercalation: Use a pipette to slowly add reaction solution A to the bentonite reaction solution B that is being sheared at high speed, add formamide, and continue to use a high-speed dispersing homogenizer to shear at high speed for 90 minutes to ensure that the reaction occurs fully and the intercalation is complete; wherein, the ratio of carbon silicon material a in the preparation of reaction solution A: sodium bentonite in the preparation of reaction solution B: formamide is 8.0:4.0:3 in g:g:ml; (5) Acidification reaction: Acidify the intercalated reaction solution with 2 mol / L hydrochloric acid solution and shake on a shaker at 180 rpm for 30 min. (6) Hydrothermal reaction: The acidified reaction solution was subjected to a hydrothermal reaction, firstly heated to 90°C at a rate of 15°C / min, and after thermal activation for 30 min, the temperature was raised to 120°C at the same rate and the hydrothermal reaction was carried out for 240 min. (7) Post-processing: After the hydrothermal reaction is completed, the mixture is allowed to stand at room temperature and the solution is centrifuged to leave a black precipitate. The precipitate is repeatedly washed by centrifugation with ultrapure water and anhydrous ethanol, a 3% mass concentration hydrogen peroxide solution is added, ultrasonic treatment is performed for 30 minutes, centrifugation is performed, ultrapure water and anhydrous ethanol are washed, the mixture is dried at 70°C, and ground through a 50-mesh sieve to obtain a gray-black solid powder, thereby obtaining a carbon-silicon intercalated composite clay material for biogas slurry additive.

2. The preparation method according to claim 1, wherein: In step (1), the collected wine lees waste and silicate tailings are mixed in a mass ratio of 4:

1.

3. The preparation method according to claim 1, wherein: The sodium bentonite in step (3) is 400 mesh.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The reaction solution after acidification in step (6) is poured into a hydrothermal reactor lined with tetrafluoroethylene for hydrothermal reaction.

5. Use of the preparation method according to any one of claims 1 to 4 in the preparation of biogas slurry additives.

6. A carbon-silicon intercalated composite clay material for biogas slurry additive prepared by the preparation method according to any one of claims 1 to 4.

7. Use of the carbon-silicon intercalated composite clay material according to claim 6 in the adsorption of ammonia nitrogen and phosphorus in biogas slurry.

8. Use of the carbon-silicon intercalated composite clay material according to claim 6 in adsorbing ammonium ions in biogas slurry.

9. Use of the carbon-silicon intercalated composite clay material according to claim 6 in promoting the precipitation adsorption of phosphate.

10. Use of the carbon-silicon intercalated composite clay material according to claim 6 in the immobilization of nitrogen and phosphorus nutrients in biogas slurry.

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