Application of phosphorus-containing layered bimetallic hydroxide composite biochar in the targeted adsorption of ammonia nitrogen and / or as a targeted adsorbent for ammonia nitrogen.

Abstract

This invention discloses the application of phosphorus-containing layered bimetallic hydroxide composite biochar in the targeted adsorption of ammonia nitrogen and / or as a targeted adsorbent for ammonia nitrogen. This invention discovers that the addition of phosphorus can improve the adsorption performance of layered bimetallic hydroxide composite biochar for ammonia nitrogen, and provides a novel method for preparing phosphorus-containing layered bimetallic hydroxide composite biochar by co-precipitating biochar with water, soluble magnesium salts, soluble trivalent iron salts, and soluble phosphates. The method of this invention can increase the number of adsorption sites and functional groups on the surface of the biochar, and the preparation method is simple, efficient, and uses inexpensive and readily available raw materials. The prepared layered bimetallic hydroxide composite biochar has broad application prospects in the field of ammonia nitrogen adsorption.

Description

Technical Field

[0001] This invention relates to the technical field of functional material preparation and solid waste resource utilization, specifically to the application of phosphorus-containing layered bimetallic hydroxide composite biochar in the directional adsorption of ammonia nitrogen and / or as a directional adsorbent for ammonia nitrogen. Background Technology

[0002] Ammonia nitrogen (NH4) + Ammonia nitrogen (AM) is a common nutrient pollutant in wastewater discharge, leading to serious water pollution problems such as eutrophication and algal blooms, threatening human health and the ecological environment. Therefore, the efficient removal of AM from water bodies has attracted widespread attention. Currently, AM removal methods mainly include chemical precipitation, membrane separation, biological methods, and adsorption. However, due to limitations in cost, efficiency, and operability, the selection of environmentally friendly and cost-effective treatment methods is a key focus. Among these, adsorption is widely used due to its low cost, simple operation, and strong practicality; therefore, finding an environmentally friendly and efficient adsorbent has become a current research hotspot.

[0003] Biochar, as a novel material for sustainable development, possesses high specific surface area, porous structure, and abundant functional groups, exhibiting certain adsorption properties and is widely used in water pollution control and agriculture. However, biochar has poor adsorption efficiency for ammonia nitrogen. Its adsorption performance can be improved through modification or by combining it with materials that have excellent adsorption effects. Layered bimetallic hydroxide (LDH) is an anionic clay with the chemical formula [M... 2+ 1-x M 3+ x (OH)2] x+ [A n- ] x / n LDH (Leyte Hydrogen Deionization) has a complex structure, consisting of positively charged main layers, negatively charged interlayer anions, and water molecules. Therefore, LDH possesses advantages such as interlayer anion exchange capacity, abundant active centers, large specific surface area, tunable layer composition, low cost, and simple preparation process, making it suitable as an adsorbent. However, LDH's tendency to aggregate and high leaching rate hinder its widespread adoption and application.

[0004] In recent years, biochar has been used as a carrier to improve the dispersibility and stability of LDHs. Many studies have combined layered bimetallic hydroxides with biochar to adsorb pollutants in water, demonstrating good adsorption properties. Zhang et al. prepared MgFe-LDH@biochar, which can adsorb inorganic nitrogen and heavy metals in water, with an adsorption capacity of 11.05 mg / g for ammonia nitrogen. Bian et al. prepared MgFe@BC, achieving a 30% removal rate of ammonia nitrogen at a dosage of 10 g / L. However, the limited number of active sites in LDHs leads to insufficient selectivity and capacity for adsorption. Summary of the Invention

[0005] To overcome the aforementioned defects and shortcomings in the prior art, the present invention provides the application of phosphorus-containing layered bimetallic hydroxide composite biochar in the directional adsorption of ammonia nitrogen and / or as a directional adsorbent for ammonia nitrogen.

[0006] The first objective of this invention is to provide the use of phosphorus-containing layered bimetallic hydroxide composite biochar in the directed adsorption of ammonia nitrogen and / or as a directed adsorbent for ammonia nitrogen.

[0007] The second objective of this invention is to provide a phosphorus-containing layered bimetallic hydroxide composite biochar.

[0008] This invention claims protection for the following:

[0009] Application of phosphorus-containing layered bimetallic hydroxide composite biochar in the directed adsorption of ammonia nitrogen and / or as a directed adsorbent for ammonia nitrogen.

[0010] The phosphorus-containing layered bimetallic hydroxide composite biochar described in this invention can be a product known in the prior art, such as the phosphorus-containing layered bimetallic hydroxide composite biochar disclosed in the prior art (DOI: 10.1016 / j.chemosphere.2021.130116). However, the prior art only discloses the application of the phosphorus-containing layered bimetallic hydroxide composite biochar prepared by this method to remediate soil contaminated by uranium plant tailings, and does not disclose the use of phosphorus-containing layered bimetallic hydroxide composite biochar for the targeted adsorption of ammonia nitrogen.

[0011] In addition, existing technologies also disclose that layered bimetallic hydroxide composite biochar (Mg-Fe LDH@BC or Mg-Al LDH@BC) prepared from Mg-Fe or Mg-Al has the function of adsorbing ammonia nitrogen. However, the experimental results of this invention show that the adsorption effect of layered bimetallic hydroxide composite biochar prepared from Mg-Fe alone is even worse than that of simple biochar. Furthermore, existing technologies do not mention that phosphorus can enhance the adsorption effect of layered bimetallic hydroxide composite biochar on ammonia nitrogen.

[0012] Therefore, as an feasible approach, the preparation method of the phosphorus-containing layered bimetallic hydroxide composite biochar can refer to the prior art and includes the following steps:

[0013] S21. Biochar is produced by pyrolysis of biomass;

[0014] S22. The biochar from step S21 is impregnated in an aqueous phosphate solution, and the product after impregnation is mixed with water, soluble magnesium salt and soluble ferric salt for co-precipitation;

[0015] S23. Pyrolyze the coprecipitated product from step S22 to obtain the phosphorus-containing layered bimetallic hydroxide composite biochar.

[0016] Preferably, in step S22, the ratio of biochar, soluble phosphate, soluble magnesium salt and soluble ferric salt is 1g:(0.0025~0.03)mol:(0.005~0.01)mol:0.0025mol.

[0017] More preferably, in step S22, the ratio of the amount of biochar, soluble phosphate, soluble magnesium salt and soluble ferric salt is 1g:0.0075mol:0.0075mol:0.0025mol.

[0018] Preferably, in step S22, the soaking time is 10 to 14 hours.

[0019] More preferably, in step S22, the soaking time is 12 hours.

[0020] Preferably, in step S23, the pyrolysis temperature is 300–500°C and the pyrolysis time is 0.5–1.5 h.

[0021] More preferably, in step S23, the pyrolysis temperature is 400°C and the pyrolysis time is 1 hour.

[0022] More preferably, the pyrolysis temperature is increased at a heating rate of 8–12 °C / min.

[0023] More preferably, the pyrolysis temperature is increased at a heating rate of 10°C / min.

[0024] Meanwhile, this invention also provides two novel methods for synthesizing phosphorus-containing layered bimetallic hydroxide composite biochar. The phosphorus-containing layered bimetallic hydroxide composite biochar prepared by these two methods exhibits significantly enhanced cation exchange capacity (CEC) and the number of oxygen-containing functional groups in the composite material due to phosphorus intercalation, thereby greatly strengthening its adsorption capacity for ammonia nitrogen.

[0025] As one feasible approach, the method for preparing the phosphorus-containing layered bimetallic hydroxide composite biochar includes the following steps:

[0026] S31. Biochar is produced by pyrolysis of biomass;

[0027] S32. The biochar obtained in step S31 is mixed with water, soluble magnesium salt, soluble ferric salt and soluble phosphate for co-precipitation to obtain the phosphorus-containing layered bimetallic hydroxide composite biochar.

[0028] Preferably, in step S32, the ratio of biochar, soluble phosphate, soluble magnesium salt and soluble ferric salt is 1g:(0.0025~0.03)mol:(0.005~0.01)mol:0.0025mol.

[0029] More preferably, in step S32, the ratio of the amount of biochar, soluble phosphate, soluble magnesium salt and soluble ferric salt is 1g:0.0075mol:0.0075mol:0.0025mol.

[0030] As one feasible approach, the method for preparing the phosphorus-containing layered bimetallic hydroxide composite biochar includes the following steps:

[0031] S41. Biochar is produced by pyrolysis of biomass;

[0032] S42. The biochar from step S41 is mixed with water, soluble magnesium salt, soluble ferric salt and soluble phosphate for co-precipitation;

[0033] S43. Pyrolyze the coprecipitated product from step S42 to obtain the phosphorus-containing layered bimetallic hydroxide composite biochar.

[0034] Preferably, in step S42, the ratio of biochar, soluble phosphate, soluble magnesium salt and soluble ferric salt is 1g:(0.0025~0.03)mol:(0.005~0.01)mol:0.0025mol.

[0035] More preferably, in step S42, the ratio of the amount of biochar, soluble phosphate, soluble magnesium salt and soluble ferric salt is 1g:0.0075mol:0.0075mol:0.0025mol.

[0036] Preferably, in step S43, the pyrolysis temperature is 300–500°C and the pyrolysis time is 0.5–1.5 h.

[0037] More preferably, in step S43, the pyrolysis temperature is 400°C and the pyrolysis time is 1 hour.

[0038] More preferably, the pyrolysis temperature is increased at a heating rate of 8–12 °C / min.

[0039] More preferably, the pyrolysis temperature is increased at a heating rate of 10°C / min.

[0040] In step S21, step S31 or step S41, the biomass is some common agricultural and forestry waste biomass in production and daily life, including but not limited to rice straw, corn straw and camellia shells.

[0041] Preferably, the biomass is corn stalks.

[0042] Preferably, the biomass is dried and pulverized into powder before pyrolysis.

[0043] More preferably, the drying is performed at 100–110°C for at least 24 hours.

[0044] More preferably, the pulverization involves pulverizing the biomass into powder with a particle size of less than 2 mm.

[0045] Preferably, in step S21, step S31 or step S41, the pyrolysis is carried out in an oxygen-free atmosphere.

[0046] As one feasible approach, the oxygen-free atmosphere is a nitrogen atmosphere.

[0047] Preferably, in step S21, step S31 or step S41, the pyrolysis temperature is 280 to 500°C and the pyrolysis time is 1 to 3 hours.

[0048] More preferably, in step S21, step S31 or step S41, the pyrolysis temperature is 300°C and the pyrolysis time is 2 hours.

[0049] More preferably, the pyrolysis temperature is increased at a heating rate of 8–12 °C / min.

[0050] More preferably, the pyrolysis temperature is increased at a heating rate of 10°C / min.

[0051] Preferably, in step S22, step S32 or step S42, the mass ratio of biochar to water is 1g:(80-120)g.

[0052] More preferably, in step S22, step S32 or step S42, the mass ratio of biochar to water is 1g:100g.

[0053] Preferably, in step S22, step S32 or step S42, the soluble magnesium salt is MgCl2.

[0054] Preferably, in step S22, step S32 or step S42, the soluble trivalent iron salt is FeCl3·6H2O.

[0055] Preferably, in step S22, step S32, or step S42, the soluble phosphate contains PO4. 3- HPO4 2- and H2PO4 - Soluble phosphates.

[0056] More preferably, in step S22, step S32 or step S42, the soluble phosphate is K2HPO4.

[0057] Preferably, in step S32 or step S42, the temperature of the co-precipitation is 60-70°C, and the time of the co-precipitation is 22-26 hours.

[0058] More preferably, the co-precipitation temperature is 65°C and the co-precipitation time is 24 hours.

[0059] Preferably, in step S32 or step S42, the co-precipitation is performed by oscillation.

[0060] More preferably, the rotational speed of the oscillation is 180 to 200 rpm.

[0061] Preferably, in step S32 or step S42, the coprecipitation is carried out under pH conditions of 10 to 11.

[0062] Preferably, in step S23 or step S43, the pyrolysis is carried out in an oxygen-free atmosphere.

[0063] As one feasible approach, the oxygen-free atmosphere is a nitrogen atmosphere.

[0064] The present invention also claims protection for phosphorus-containing layered bimetallic hydroxide composite biochar prepared by any of the above-described preparation methods.

[0065] The adsorption mechanism of ammonia nitrogen by phosphorus-containing layered bimetallic hydroxide composite biochar mainly includes chemisorption, cation exchange, electrostatic interaction, and hydrogen bonding. During this process, Mg can combine with P and ammonia nitrogen to form MgNH4PO4, and a large number of hydroxide ions within the metal layer also associate with ammonia nitrogen. Simultaneously, a large amount of Fe... 3+ and Mg 2+ The material's cation exchange capacity has been improved, enabling it to react with NH4+. + The exchange process enables efficient removal of ammonia nitrogen from water.

[0066] Compared with the prior art, the present invention has the following beneficial effects:

[0067] This invention discloses the application of phosphorus-containing layered bimetallic hydroxide composite biochar in the targeted adsorption of ammonia nitrogen and / or as a targeted adsorbent for ammonia nitrogen. The inventors unexpectedly discovered that the addition of phosphorus can improve the adsorption performance of the composite biochar for ammonia nitrogen. Furthermore, the inventors also provide two novel methods for preparing phosphorus-containing layered bimetallic hydroxide composite biochar, which exhibits higher ammonia nitrogen recovery rates than those prepared by known methods. Attached Figure Description

[0068] Figure 1 The diagram shows the preparation process of phosphorus-containing layered bimetallic hydroxide composite biochar in Examples 2-6.

[0069] Figure 2 The infrared spectra of the phosphorus-containing layered bimetallic hydroxide composite biochar prepared in Examples 2-6 are shown.

[0070] Figure 3 The maximum equilibrium adsorption capacity is the composite biochar prepared in Examples 1-7 and Comparative Examples 1-5. Detailed Implementation

[0071] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0072] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0073] Example 1: A method for preparing phosphorus-containing layered bimetallic hydroxide composite biochar

[0074] This embodiment provides a method for preparing phosphorus-containing layered bimetallic hydroxide composite biochar, including the following steps:

[0075] S1. Place the corn stalks in a 105℃ forced-air drying oven for 24 hours. After drying, take them out and crush them with a pulverizer to obtain corn stalk powder.

[0076] S2. Place the corn stalk powder from step S1 into a tube furnace, heat it to 300℃ for 2 hours under a nitrogen atmosphere at a heating rate of 10℃ / min, and then cool it naturally to room temperature to obtain primary corn stalk biochar, named BC3.

[0077] S3. Place the primary corn stalk biochar BC3 from step S2 into an Erlenmeyer flask, and add water, FeCl3·6H2O, MgCl2, and KH2PO4, wherein the mass ratio of water to biochar is 100:1, and the amount of FeCl3·6H2O added is 0.0025 mol / g. 初级玉米秸秆生物炭BC3 The amount of KH2PO4 added was 0.0075 mol / g. 初级玉米秸秆生物炭BC3 The molar ratio of MgCl2 to FeCl3·6H2O was 3:1. The pH of the system was adjusted to 10–11 using NaOH, and the reaction was carried out at 65°C with shaking for 24 hours. The solid was filtered, dried, ground, and sieved to obtain a phosphorus-containing layered bimetallic hydroxide composite biochar, named Mg3Fe / BC-PO.

[0078] Example 2: A method for preparing phosphorus-containing layered bimetallic hydroxide composite biochar

[0079] This embodiment provides a method for preparing phosphorus-containing layered bimetallic hydroxide composite biochar. Figure 1 The process includes the following steps:

[0080] S1. Place the corn stalks in a 105℃ forced-air drying oven for 24 hours. After drying, take them out and crush them with a pulverizer to obtain corn stalk powder.

[0081] S2. Place the corn stalk powder from step S1 into a tube furnace, heat it to 300℃ for 2 hours under a nitrogen atmosphere at a heating rate of 10℃ / min, and then cool it naturally to room temperature to obtain primary corn stalk biochar, named BC3.

[0082] S3. Place the primary corn stalk biochar BC3 from step S2 into an Erlenmeyer flask, and add water, FeCl3·6H2O, MgCl2, and KH2PO4, wherein the mass ratio of water to biochar is 100:1, and the amount of FeCl3·6H2O added is 0.0025 mol / g. 初级玉米秸秆生物炭BC3 The amount of KH2PO4 added was 0.0075 mol / g. 初级玉米秸秆生物炭BC3 The molar ratio of MgCl2 to FeCl3·6H2O was 2:1. The pH of the system was adjusted to 10-11 using NaOH, and the reaction was carried out at 65℃ with shaking for 24 hours. The solid was filtered, dried, ground, and sieved to obtain the primary product of phosphorus-containing layered bimetallic hydroxide composite biochar.

[0083] S4. The phosphorus-containing layered bimetallic hydroxide composite biochar primary product was placed in a tube furnace and pyrolyzed at 300℃ for 1 hour under a nitrogen atmosphere at a heating rate of 10℃ / min. After natural cooling to room temperature, the phosphorus-containing layered bimetallic hydroxide composite biochar was obtained and named Mg2Fe / BC-P3.

[0084] Example 3: A method for preparing phosphorus-containing layered bimetallic hydroxide composite biochar

[0085] This embodiment prepares phosphorus-containing layered bimetallic hydroxide composite biochar according to Example 2. Figure 1 The difference is that the molar ratio of MgCl2 and FeCl3·6H2O in step S3 is 3:1.

[0086] The phosphorus-containing layered bimetallic hydroxide composite biochar prepared in this embodiment is named Mg3Fe / BC-P3.

[0087] Example 4: A method for preparing phosphorus-containing layered bimetallic hydroxide composite biochar

[0088] This embodiment prepares phosphorus-containing layered bimetallic hydroxide composite biochar according to Example 2. Figure 1 The difference is that the molar ratio of MgCl2 and FeCl3·6H2O in step S3 is 4:1.

[0089] The phosphorus-containing layered bimetallic hydroxide composite biochar prepared in this embodiment is named Mg4Fe / BC-P3.

[0090] Example 5: A method for preparing phosphorus-containing layered bimetallic hydroxide composite biochar

[0091] This embodiment prepares phosphorus-containing layered bimetallic hydroxide composite biochar according to Example 2. Figure 1 The difference lies in the following: in step S3, the molar ratio of MgCl2 to FeCl3·6H2O is 3:1; in step S4, the pyrolysis temperature is 400℃.

[0092] The phosphorus-containing layered bimetallic hydroxide composite biochar prepared in this embodiment is named Mg3Fe / BC-P4.

[0093] Example 6: A method for preparing phosphorus-containing layered bimetallic hydroxide composite biochar

[0094] This embodiment prepares phosphorus-containing layered bimetallic hydroxide composite biochar according to Example 2. Figure 1 The difference lies in the following: in step S3, the molar ratio of MgCl2 to FeCl3·6H2O is 3:1; in step S4, the pyrolysis temperature is 500℃.

[0095] The phosphorus-containing layered bimetallic hydroxide composite biochar prepared in this embodiment is named Mg3Fe / BC-P5.

[0096] Example 7: A method for preparing phosphorus-containing layered bimetallic hydroxide composite biochar

[0097] This embodiment prepares layered bimetallic hydroxide composite biochar according to Example 5, the difference being: in step S3, 0.0075 mol KH2PO4 and 1 g BC3 are first added and mixed and impregnated for 12 h, then filtered and dried, and then water, MgCl2 and FeCl3·6H2O are added, with the molar ratio of MgCl2 and FeCl3·6H2O being 3:1.

[0098] The layered bimetallic hydroxide composite biochar prepared in this embodiment is named P-Mg3Fe / BC4.

[0099] Comparative Example 1

[0100] This comparative example prepares layered bimetallic hydroxide composite biochar according to Example 2, the difference being that KH2PO4 is not added in step S3.

[0101] The layered bimetallic hydroxide composite biochar prepared in this comparative example is named Mg2Fe / BC3.

[0102] Comparative Example 2

[0103] This comparative example prepares layered bimetallic hydroxide composite biochar according to Example 2, the difference being that: KH2PO4 is not added in step S3, and the molar ratio of MgCl2 and FeCl3·6H2O is 3:1.

[0104] The layered bimetallic hydroxide composite biochar prepared in this comparative example is named Mg3Fe / BC3.

[0105] Comparative Example 3

[0106] This comparative example prepares layered bimetallic hydroxide composite biochar according to Example 2, the difference being that: KH2PO4 is not added in step S3, and the molar ratio of MgCl2 and FeCl3·6H2O is 4:1.

[0107] The layered bimetallic hydroxide composite biochar prepared in this comparative example is named Mg4Fe / BC3.

[0108] Comparative Example 4

[0109] This comparative example provides a method for preparing biochar, comprising the following steps:

[0110] S1. Place the corn stalks in a 105℃ forced-air drying oven for 24 hours. After drying, take them out and crush them with a pulverizer to obtain corn stalk powder.

[0111] S2. Place the corn stalk powder from step S1 into a tube furnace, heat it to 300℃ for 2 hours under a nitrogen atmosphere at a heating rate of 10℃ / min, and then cool it naturally to room temperature to obtain primary corn stalk biochar, named BC3.

[0112] Comparative Example 5

[0113] This comparative example prepares layered bimetallic hydroxide composite biochar according to Example 5, the difference being that in step S3, 0.0075 mol KH2PO4 is replaced with acetic acid (CH3COOH), and the molar ratio of MgCl2 to FeCl3·6H2O is 3:1.

[0114] The layered bimetallic hydroxide composite biochar prepared in this comparative example is named Mg3Fe / BC-COOH.

[0115] Test Example 1

[0116] I. Experimental Methods

[0117] Fourier transform infrared spectroscopy was used to test the phosphorus-containing layered bimetallic hydroxide composite biochar prepared in Examples 2-6 and the primary corn straw biochar prepared in Comparative Example 4.

[0118] II. Experimental Results

[0119] Functional group analysis of phosphorus-containing layered bimetallic hydroxide composite biochar and primary corn straw biochar (Comparative Example 4) revealed that the addition of KH₂PO₄ significantly increased the PO functional groups in the phosphorus-containing layered bimetallic hydroxide composite biochar prepared in Examples 2-6, leading to phosphorus intercalation and the generation of a large amount of phosphate. Figure 2 ).

[0120] After adsorbing ammonia nitrogen, the PO bonds were significantly reduced, and phosphorus in the material was consumed, proving that phosphorus intercalation increased the favorable sites on the material surface. Figure 2 ).

[0121] Test Example 2

[0122] I. Experimental Methods

[0123] The materials prepared in Examples 1-7 and Comparative Examples 1-5 were investigated for the directional adsorption of ammonia nitrogen in wastewater. The adsorption experimental procedure was as follows: 0.05 g of sample was weighed and placed in a 50 mL centrifuge tube, and 30 mL of NH4Cl solution (concentration 100 mg·L⁻¹) was added. -1 Afterwards, it was placed in a constant temperature shaker at 25℃ and shaken for 24 hours. Then it was removed and filtered using a 0.45μm aqueous phase filter membrane. The concentration of ammonia nitrogen in the filtrate was determined using Nessler's reagent method (HJ 535-2009). Each condition was set up for 3 replicates and the average value was taken. The adsorption capacity Q of ammonia nitrogen by biochar was calculated according to formula (1). e mg·g -1 .

[0124]

[0125] In the formula: V is the volume of the ammonia nitrogen standard solution, L; C0 and C are the concentrations of the ammonia nitrogen solution before adsorption and the concentration of the remaining ammonia nitrogen solution after adsorption equilibrium, respectively, mg·L. -1 m represents the mass of the sample added, in grams.

[0126] II. Experimental Results

[0127] The results are as follows Figure 3 As shown in Table 1, the maximum equilibrium adsorption capacity of the phosphorus-containing layered bimetallic hydroxide composite biochar prepared in Example 5 for ammonia nitrogen was 38.31 mg / g, which was slightly higher than that of the phosphorus-containing layered bimetallic hydroxide composite biochar in Example 2, and significantly higher than that of Examples 1, 3, 4, 6, 7 and Comparative Examples 1 to 5.

[0128] In addition, as can be seen from Table 1, the adsorption effect of phosphorus-containing layered bimetallic hydroxide composite biochar prepared in Examples 1-7 on ammonia nitrogen is significantly better than that in Comparative Examples 1-5. This indicates that the addition of phosphorus can improve the adsorption effect of the prepared layered bimetallic hydroxide composite biochar on ammonia nitrogen, and the formation of phosphorus intercalation has a more obvious effect on improving the adsorption effect of ammonia nitrogen.

[0129] The above results also indicate that, under the same conditions, the adsorption effect of phosphorus-containing layered bimetallic hydroxide composite biochar on ammonia nitrogen is significantly better than that of non-phosphorus and layered bimetallic hydroxide containing acetate intercalation. Furthermore, the pyrolysis temperature, Mg / Fe ratio, and the order of addition of KH2PO4 all have a significant impact on the ammonia nitrogen adsorption performance of the prepared composite biochar. Taking all factors into consideration, the optimal preparation conditions are a Mg / Fe molar ratio of 3:1 and a pyrolysis temperature of 400℃.

[0130] Table 1 Maximum equilibrium adsorption capacity of composite biochar for ammonia nitrogen

[0131]

[0132] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. Application of phosphorus-containing layered bimetallic hydroxide composite biochar in the directed adsorption of ammonia nitrogen and / or as a directed adsorbent for ammonia nitrogen.

2. The application according to claim 1, characterized in that, The preparation method of the phosphorus-containing layered bimetallic hydroxide composite biochar includes the following steps: S21. Biochar is produced by pyrolysis of biomass; S22. The biochar from step S21 is impregnated in an aqueous phosphate solution, and the product after impregnation is mixed with water, soluble magnesium salt and soluble ferric salt for co-precipitation; S23. Pyrolyze the coprecipitated product from step S22 to obtain the phosphorus-containing layered bimetallic hydroxide composite biochar.

3. The application according to claim 1, characterized in that, The preparation method of the phosphorus-containing layered bimetallic hydroxide composite biochar includes the following steps: S31. Biochar is produced by pyrolysis of biomass; S32. The biochar obtained in step S31 is mixed with water, soluble magnesium salt, soluble ferric salt and soluble phosphate for co-precipitation to obtain the phosphorus-containing layered bimetallic hydroxide composite biochar.

4. The application according to claim 1, characterized in that, The preparation method of the phosphorus-containing layered bimetallic hydroxide composite biochar includes the following steps: S41. Biochar is produced by pyrolysis of biomass; S42. The biochar from step S41 is mixed with water, soluble magnesium salt, soluble ferric salt and soluble phosphate for co-precipitation; S43. Pyrolyze the coprecipitated product from step S42 to obtain the phosphorus-containing layered bimetallic hydroxide composite biochar.

5. The application according to any one of claims 2 to 4, characterized in that, The ratio of biochar, soluble phosphate, soluble magnesium salt and soluble ferric salt is 1g:(0.0025~0.03)mol:(0.005~0.01)mol:0.0025mol.

6. The application according to claim 2 or 4, characterized in that, In step S23 or step S43, the pyrolysis temperature is 300-500℃.

7. The application according to claim 2 or 4, characterized in that, In step S23 or step S43, the pyrolysis time is 0.5 to 1.5 hours.

8. The application according to any one of claims 2 to 4, characterized in that, The mass ratio of biochar to water is 1g:(80-120)g.

9. A phosphorus-containing layered bimetallic hydroxide composite biochar, characterized in that, It is prepared by the following method: S31. Biochar is produced by pyrolysis of biomass; S32. The biochar obtained in step S31 is mixed with water, soluble magnesium salt, soluble ferric salt and soluble phosphate for co-precipitation to obtain the phosphorus-containing layered bimetallic hydroxide composite biochar. The ratio of biochar, soluble phosphate, soluble magnesium salt and soluble ferric salt is 1g:(0.0025~0.03)mol:(0.005~0.01)mol:0.0025mol.

10. A phosphorus-containing layered bimetallic hydroxide composite biochar, characterized in that, It is prepared by the following method: S41. Biochar is produced by pyrolysis of biomass; S42. The biochar from step S41 is mixed with water, soluble magnesium salt, soluble ferric salt and soluble phosphate for co-precipitation; The ratio of biochar, soluble phosphate, soluble magnesium salt, and soluble ferric salt is 1 g : (0.0025–0.03) mol : (0.005–0.01) mol : 0.0025 mol; S43. Pyrolyze the coprecipitated product from step S42 to obtain the phosphorus-containing layered bimetallic hydroxide composite biochar.

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