Soil remediation agent for acid soil and preparation method of soil remediation agent

Abstract

The invention discloses a soil remediation agent for acid soil and a preparation method of the soil remediation agent, and relates to the field of soil remediation. When the soil remediation agent for the acid soil is prepared, 1-amino-1H-imidazole-4, 5-dicarboxylic acid diethyl ester and hydrazine hydrate are subjected to a reaction, and a polymeric monomer is prepared; uniformly mixing calcite powder, a polymeric monomer and benzoquinoline-4, 7-dicarboxaldehyde, so as to obtain modified calcite; the preparation method comprises the following steps: uniformly mixing biochar, 2-(bromomethyl) terephthalic acid and chromic nitrate nonahydrate to prepare modified biochar; the preparation method comprises the following steps: uniformly mixing ferric oxide powder, vinyl trimethoxy alkane, sodium alginate and calcium chloride, and oxidizing with m-chloroperoxybenzoic acid to obtain modified ferric oxide; uniformly mixing the modified calcite and the modified biochar with the modified ferric oxide to obtain the soil remediation agent for the acid soil. The soil remediation agent for acid soil prepared by the invention has excellent heavy metal complexing property, water retention property, carbon sequestration property and acid-base lasting adjustability.

Description

Technical Field

[0001] The invention relates to the field of soil remediation, in particular to a soil remediation agent for acidic soil and a preparation method thereof. Background Art

[0002] As the foundation for human survival and development, soil has played an indispensable role throughout human history. In recent years, the rapid development of industrialization and urbanization has caused some soils to be contaminated by heavy metals. Heavy metals have the characteristics of high toxicity, persistence and easy accumulation, which will change the soil structure, deteriorate the soil environment, and thus destroy the ecosystem environment. In addition, soil acidification increases the activity of heavy metal elements in the soil, and heavy metals are more easily absorbed by plants in the soil, transferred and spread through the food chain, causing certain harm to human health. Therefore, the present invention prepares a soil remediation agent for acidic soil with excellent heavy metal complexing properties. Summary of the invention

[0003] The purpose of the present invention is to provide a soil remediation agent for acidic soil and a preparation method thereof, so as to solve the problems existing in the prior art.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] A soil remediation agent for acidic soil is obtained by uniformly mixing modified calcite, modified biochar and modified ferric oxide.

[0006] As an optimization, the modified biochar is composed of biochar, 2-

[0007] It is prepared by mixing (bromomethyl)terephthalic acid and chromium nitrate nonahydrate.

[0008] As an optimization, the biochar model is 200 mesh and comes from Henan Jiahe Water Purification Materials Co., Ltd.

[0009] As an optimization, the modified ferric oxide is prepared by mixing ferric oxide powder, vinyl trimethoxyalkane, sodium alginate and calcium chloride and then oxidizing with m-chloroperbenzoic acid.

[0010] As an optimization, the ferric oxide powder model is 200 mesh and comes from Lingshou County Jiashuo Building Materials Processing Co., Ltd.

[0011] As an optimization, the modified calcite is composed of 1-amino-1H-imidazole-4,5-

[0012] The polymerization monomer is obtained by reacting diethyl dicarboxylate with hydrazine hydrate, and then mixed with calcite powder and benzoquinoline-4,7-dicarboxaldehyde to obtain the obtained product.

[0013] As an optimization, the calcite powder model is 600 mesh and comes from Hebei Leijiang New Materials Technology Co., Ltd.

[0014] A method for preparing a soil remediation agent for acidic soil comprises the following preparation steps:

[0015] (1) 1-amino-1H-imidazole-4,5-

[0016] Diethyl dicarboxylate, hydrazine hydrate and anhydrous ethanol are mixed in a mass ratio of 1:(5-7):(44-46), refluxed at 75-85°C for 11-13 hours, naturally cooled to room temperature and filtered, washed with deionized water and anhydrous ethanol for 3-5 times respectively, and dried at 65-75°C for 6-8 hours to obtain a polymerization monomer;

[0017] (2) Calcite powder, polymerization monomer, benzoquinoline-4,7-

[0018] Diformaldehyde and acetonitrile are mixed in a mass ratio of 1:(1.8-1.9):(1.7-1.8):(50-60), ultrasonically dispersed for 1-3 min, 9-11 times the mass of calcite powder and 11-13 mol / L acetic acid aqueous solution are added, and the mixture is allowed to stand at 20-30° C. for 2-4 days and then centrifuged, washed with acetone and tetrahydrofuran for 3-5 times respectively, and dried at 55-65° C. for 11-13 h to obtain modified calcite;

[0019] (3) Biochar, 2-

[0020] (Bromomethyl)terephthalic acid, chromium nitrate nonahydrate and 85% to 95% by volume of N,N-

[0021] The dimethylformamide aqueous solution is mixed in a mass ratio of 1: (55-57): (45-55): (950-1050), reacted at 125-135°C for 5-7h in a polytetrafluoroethylene-lined autoclave, naturally cooled to room temperature and then filtered, washed with deionized water for 3-5 times, activated with methanol at 75-85°C for 23-25h, and dried at 95-105°C for 6-8h to obtain modified biochar;

[0022] (4) Mix ferric oxide, vinyl trimethoxyethane and 1-3 mg / ml sodium alginate solution in a mass ratio of 1:(0.6-0.8):(33-34), stir at 25-35°C and 500-700 rpm for 25-35 min, and drop into a 0.01-0.03 mol / L calcium chloride solution with a mass of 16-17 times that of ferric oxide using a 1.1-1.3 mm syringe pump. After standing for 1-2 h, filter and wash with deionized water for 3 hours. ~5 times, freeze-drying to obtain pre-modified ferric oxide; mixing pre-modified ferric oxide, m-chloroperbenzoic acid and tetrahydrofuran in a mass ratio of 1:(2.4~2.6):(14~16), ultrasonically dispersing for 20~30 minutes, stirring at 30~40℃ for 55~65 minutes, filtering, washing with 9%~11% sodium hydroxide solution and tetrahydrofuran for 3~5 times respectively, drying at 55~65℃ for 8~10 hours, and obtaining modified ferric oxide;

[0023] (5) The modified calcite, modified biochar and methanol were mixed in a mass ratio of 1: (0.09-0.11): (19-21), stirred at 20-30°C and 300-400 rpm for 25-35 min, heated to 45-55°C and continued to stir for 47-49 h, naturally cooled to room temperature and then centrifuged, washed with deionized water for 3-5 times, dried at 65-75°C for 9-11 h, and modified ferric oxide in an amount of 0.11-0.13 times the mass of the modified calcite was added and mixed to obtain a soil remediation agent for acidic soil.

[0024] As an optimization, the reaction equation of the polymerization monomer in step (1) is:

[0025]

[0026] As an optimization, the reaction equation of the modified calcite in step (2) is:

[0027]

[0028] As an optimization, the reaction equation for modifying the biochar in step (3) is:

[0029] As an optimization, the reaction equation for the modified ferric oxide in step (4) is:

[0030]

[0031] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0032] When preparing the soil remediation agent for acidic soil, the present invention comprises 1-amino-1H-imidazole-4,5-

[0033] Diethyl dicarboxylate and hydrazine hydrate are reacted to obtain a polymerization monomer; calcite powder, the polymerization monomer and benzoquinoline-4,7-dicarboxaldehyde are mixed to obtain modified calcite; biochar, 2-

[0034] (Bromomethyl)terephthalic acid and chromium nitrate nonahydrate are mixed to obtain modified biochar; ferric oxide powder, vinyltrimethoxyethane, sodium alginate and calcium chloride are mixed and then oxidized with meta-chloroperbenzoic acid to obtain modified ferric oxide; modified calcite, modified biochar and modified ferric oxide are mixed to obtain a soil remediation agent for acidic soil.

[0035] First, 1-amino-1H-imidazole-4,5-

[0036] Diethyl dicarboxylate and hydrazine hydrate are reacted to obtain a polymerization monomer; calcite powder, the polymerization monomer and benzoquinoline-4,7-dicarboxaldehyde are mixed to obtain modified calcite; biochar, 2-

[0037] The modified biochar was prepared by mixing (bromomethyl) terephthalic acid and chromium nitrate nonahydrate; the two ester groups on diethyl 1-amino-1H-imidazole-4,5-dicarboxylate were converted into hydrazide groups by using hydrazine hydrate, and then reacted with benzoquinoline-4,7-

[0038] The aldehyde group on diformaldehyde reacts to form a hydrazone bond, which is polymerized and wrapped on the surface of calcite to avoid the direct release of calcite powder and prolong the action time of calcite powder. The hydrazone bond breaks under acidic conditions, promotes the release of calcite powder, enhances the pH adjustment effect of calcite, and improves the acid-base adjustment durability of the soil remediation agent for acidic soil; at the same time, the nitrogen atom on benzoquinoline carries a lone pair of electrons, which can form a coordination bond with heavy metal ions, thereby improving the heavy metal complexing property of the soil remediation agent for acidic soil; through 2-

[0039] (Bromomethyl)terephthalic acid and chromium nitrate nonahydrate composite biochar form a metal organic framework, increase the specific surface area and active sites, adsorb and coordinate heavy metal ions, and improve the heavy metal complexing property of soil remediation agents for acidic soils.

[0040] Secondly, ferric oxide powder, vinyl trimethoxyalkane, sodium alginate and calcium chloride are mixed and then oxidized with meta-chloroperbenzoic acid to obtain modified ferric oxide; modified calcite, modified biochar and modified ferric oxide are mixed to obtain a soil remediation agent for acidic soil; ferric oxide is wrapped by complexing calcium ions with sodium alginate to form a gel-like substance between soil particles, which promotes the formation of soil aggregate structure and improves the water retention of the soil remediation agent for acidic soil; the carbon-carbon double bonds grafted on the surface of ferric oxide are oxidized by meta-chloroperbenzoic acid to form epoxy groups, and the epoxy groups are used to react with carbon dioxide to reduce the release of carbon dioxide and improve the carbon fixation of the soil remediation agent for acidic soil; at the same time, the bromine on the metal organic skeleton in the modified biochar reacts with the imidazole ring on the modified calcite to form a quaternary ammonium reaction, and the bromine imidazole salt can further catalyze the cyclization reaction and enhance the carbon fixation of the soil remediation agent for acidic soil. DETAILED DESCRIPTION

[0041] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0042] The raw materials used in the following examples and comparative examples are all commercially available:

[0043] The biochar model is 200 mesh and comes from Henan Jiahe Water Purification Materials Co., Ltd.;

[0044] The ferric oxide powder is of 200 mesh and comes from Lingshou County Jiashuo Building Materials Processing Co., Ltd.

[0045] The calcite powder model is 600 mesh and comes from Hebei Leijiang New Materials Technology Co., Ltd.

[0046] Embodiment 1:

[0047] A method for preparing a soil remediation agent for acidic soil, the method comprising the following preparation steps:

[0048] (1) 1-amino-1H-imidazole-4,5-

[0049] Diethyl dicarboxylate, hydrazine hydrate and anhydrous ethanol were mixed in a mass ratio of 1:5:44, refluxed at 75°C for 13 hours, naturally cooled to room temperature and filtered, washed with deionized water and anhydrous ethanol for three times respectively, and dried at 65°C for 8 hours to obtain a polymerization monomer;

[0050] (2) Calcite powder, polymerization monomer, benzoquinoline-4,7-

[0051] Diformaldehyde and acetonitrile were mixed at a mass ratio of 1:1.8:1.7:50, ultrasonically dispersed for 1 min, 11 mol / L acetic acid aqueous solution (9 times the mass of calcite powder) was added, and the mixture was allowed to stand at 20°C for 4 days and then centrifuged. The mixture was washed with acetone and tetrahydrofuran for 3 times respectively, and dried at 55°C for 13 h to obtain modified calcite.

[0052] (3) Biochar, 2-

[0053] (Bromomethyl)terephthalic acid, chromium nitrate nonahydrate and 85% by volume of N,N-

[0054] The dimethylformamide aqueous solution was mixed at a mass ratio of 1:55:45:950, reacted at 125°C for 7 hours in a polytetrafluoroethylene-lined autoclave, naturally cooled to room temperature and then filtered, washed with deionized water three times, activated with methanol at 75°C for 25 hours, and dried at 95°C for 8 hours to obtain modified biochar;

[0055] (4) Mix ferric oxide, vinyl trimethoxy alkane and 1 mg / ml sodium alginate solution in a mass ratio of 1:0.6:33, stir at 25°C and 500 rpm for 35 minutes, and use a 1.1 mm syringe pump to drop into a 0.01 mol / L calcium chloride solution that is 16 times the mass of ferric oxide. After standing for 1 hour, filter, wash with deionized water 3 times, and freeze-dry to obtain pre-modified ferric oxide; mix pre-modified ferric oxide, m-chloroperbenzoic acid and tetrahydrofuran in a mass ratio of 1:2.4:14, ultrasonically disperse for 20 minutes, stir at 30°C for 65 minutes, filter, wash with 9% sodium hydroxide solution and tetrahydrofuran 3 times, and dry at 55°C for 10 hours to obtain modified ferric oxide;

[0056] (5) The modified calcite, modified biochar and methanol were mixed in a mass ratio of 1:0.09:19, stirred at 20 °C and 300 rpm for 35 min, heated to 45 °C and stirred for 49 h, naturally cooled to room temperature and centrifuged, washed with deionized water for 3 times, dried at 65 °C for 11 h, and modified ferric oxide (0.11 times the mass of modified calcite) was added and mixed to obtain a soil remediation agent for acidic soil.

[0057] Embodiment 2:

[0058] A method for preparing a soil remediation agent for acidic soil, the method comprising the following preparation steps:

[0059] (1) 1-amino-1H-imidazole-4,5-

[0060] Diethyl dicarboxylate, hydrazine hydrate and anhydrous ethanol were mixed in a mass ratio of 1:6:45, refluxed at 80°C for 12 hours, naturally cooled to room temperature and then filtered, washed with deionized water and anhydrous ethanol for 4 times respectively, and dried at 70°C for 7 hours to obtain a polymerized monomer;

[0061] (2) Calcite powder, polymerization monomer, benzoquinoline-4,7-

[0062] Diformaldehyde and acetonitrile were mixed in a mass ratio of 1:1.85:1.75:55, ultrasonically dispersed for 2 minutes, and a 12 mol / L acetic acid aqueous solution of 10 times the mass of the calcite powder was added. The mixture was allowed to stand at 25°C for 3 days and then centrifuged. The mixture was washed with acetone and tetrahydrofuran for 4 times respectively, and dried at 60°C for 12 hours to obtain modified calcite.

[0063] (3) Biochar, 2-

[0064] (Bromomethyl)terephthalic acid, chromium nitrate nonahydrate and 90% by volume of N,N-

[0065] The dimethylformamide aqueous solution was mixed at a mass ratio of 1:56:50:1000, reacted at 130°C for 6 hours in a polytetrafluoroethylene-lined autoclave, naturally cooled to room temperature and then filtered, washed with deionized water for 4 times, activated with methanol at 80°C for 24 hours, and dried at 100°C for 7 hours to obtain modified biochar;

[0066] (4) Mix ferric oxide, vinyl trimethoxy alkane and 2 mg / ml sodium alginate solution in a mass ratio of 1:0.7:33.5, stir at 30°C and 600 rpm for 30 min, and use a 1.2 mm syringe pump to drop into a 0.02 mol / L calcium chloride solution that is 16.5 times the mass of ferric oxide. After standing for 1.5 hours, filter, wash with deionized water 4 times, and freeze-dry to obtain pre-modified ferric oxide; mix pre-modified ferric oxide, m-chloroperbenzoic acid and tetrahydrofuran in a mass ratio of 1:2.5:15, ultrasonically disperse for 25 minutes, stir at 35°C for 60 minutes, filter, wash with 10% sodium hydroxide solution and tetrahydrofuran 4 times, and dry at 60°C for 9 hours to obtain modified ferric oxide;

[0067] (5) Modified calcite, modified biochar and methanol were mixed in a mass ratio of 1:0.1:20, stirred at 25 °C and 350 rpm for 30 min, heated to 50 °C and stirred for 48 h, naturally cooled to room temperature and centrifuged, washed with deionized water for 4 times, dried at 70 °C for 10 h, and modified ferric oxide (0.12 times the mass of modified calcite) was added and mixed to obtain a soil remediation agent for acidic soil.

[0068] Embodiment 3:

[0069] A method for preparing a soil remediation agent for acidic soil, the method comprising the following preparation steps:

[0070] (1) 1-amino-1H-imidazole-4,5-

[0071] Diethyl dicarboxylate, hydrazine hydrate and anhydrous ethanol were mixed in a mass ratio of 1:7:46, refluxed at 85°C for 11 hours, naturally cooled to room temperature and filtered, washed with deionized water and anhydrous ethanol for 5 times respectively, and dried at 75°C for 6 hours to obtain a polymerized monomer;

[0072] (2) Calcite powder, polymerization monomer, benzoquinoline-4,7-

[0073] Diformaldehyde and acetonitrile were mixed at a mass ratio of 1:1.9:1.8:60, ultrasonically dispersed for 3 minutes, and a 13 mol / L acetic acid aqueous solution of 11 times the mass of the calcite powder was added. The mixture was allowed to stand at 30°C for 2 days and then centrifuged. The mixture was washed with acetone and tetrahydrofuran for 5 times respectively, and dried at 65°C for 11 hours to obtain modified calcite.

[0074] (3) Biochar, 2-

[0075] (Bromomethyl)terephthalic acid, chromium nitrate nonahydrate and 95% by volume of N,N-

[0076] The dimethylformamide aqueous solution was mixed at a mass ratio of 1:57:55:1050, reacted at 135°C for 5 hours in a polytetrafluoroethylene-lined autoclave, naturally cooled to room temperature and then filtered, washed with deionized water 5 times, activated with methanol at 85°C for 23 hours, and dried at 105°C for 6 hours to obtain modified biochar;

[0077] (4) Mix ferric oxide, vinyl trimethoxy alkane and 3 mg / ml sodium alginate solution in a mass ratio of 1:0.8:34, stir at 35°C and 700 rpm for 25 min, and use a 1.3 mm syringe pump to drop into a 0.03 mol / L calcium chloride solution that is 17 times the mass of ferric oxide. After standing for 2 hours, filter, wash with deionized water 5 times, and freeze-dry to obtain pre-modified ferric oxide; mix pre-modified ferric oxide, m-chloroperbenzoic acid and tetrahydrofuran in a mass ratio of 1:2.6:16, ultrasonically disperse for 30 minutes, stir at 40°C for 55 minutes, filter, wash with 11% sodium hydroxide solution and tetrahydrofuran 5 times, and dry at 65°C for 8 hours to obtain modified ferric oxide;

[0078] (5) The modified calcite, modified biochar and methanol were mixed in a mass ratio of 1:0.11:21, stirred at 30 °C and 400 rpm for 25 min, heated to 55 °C and stirred for 47 h, cooled naturally to room temperature and centrifuged, washed with deionized water for 5 times, dried at 75 °C for 9 h, and modified ferric oxide (0.13 times the mass of the modified calcite) was added and mixed to obtain a soil remediation agent for acidic soil.

[0079] Comparative Example 1:

[0080] A method for preparing a soil remediation agent for acidic soil, the method comprising the following preparation steps:

[0081] (1) 1-amino-1H-imidazole-4,5-

[0082] Diethyl dicarboxylate, hydrazine hydrate and anhydrous ethanol were mixed in a mass ratio of 1:6:45, refluxed at 80°C for 12 hours, naturally cooled to room temperature and then filtered, washed with deionized water and anhydrous ethanol for 4 times respectively, and dried at 70°C for 7 hours to obtain a polymerized monomer;

[0083] (2) Calcite powder, polymerization monomer, benzoquinoline-4,7-

[0084] Diformaldehyde and acetonitrile were mixed in a mass ratio of 1:1.85:1.75:55, ultrasonically dispersed for 2 minutes, and a 12 mol / L acetic acid aqueous solution of 10 times the mass of the calcite powder was added. The mixture was allowed to stand at 25°C for 3 days and then centrifuged. The mixture was washed with acetone and tetrahydrofuran for 4 times respectively, and dried at 60°C for 12 hours to obtain modified calcite.

[0085] (3) Biochar, 2-

[0086] (Bromomethyl)terephthalic acid, chromium nitrate nonahydrate and 90% by volume of N,N-

[0087] The dimethylformamide aqueous solution was mixed at a mass ratio of 1:56:50:1000, reacted at 130°C for 6 hours in a polytetrafluoroethylene-lined autoclave, naturally cooled to room temperature and then filtered, washed with deionized water for 4 times, activated with methanol at 80°C for 24 hours, and dried at 100°C for 7 hours to obtain modified biochar;

[0088] (4) Mix ferric oxide, vinyl trimethoxyethane and 2 mg / ml sodium alginate solution in a mass ratio of 1:0.7:33.5, stir at 30°C and 600 rpm for 30 min, and use a 1.2 mm syringe pump to drop into a 0.02 mol / L calcium chloride solution that is 16.5 times the mass of ferric oxide. After standing for 1.5 h, filter, wash with deionized water 4 times, and freeze-dry to obtain pre-modified ferric oxide;

[0089] (5) Modified calcite, modified biochar and methanol were mixed in a mass ratio of 1:0.1:20, stirred at 25 °C and 350 rpm for 30 min, heated to 50 °C and stirred for 48 h, naturally cooled to room temperature and centrifuged, washed with deionized water for 4 times, dried at 70 °C for 10 h, and modified ferric oxide (0.12 times the mass of modified calcite) was added and mixed to obtain a soil remediation agent for acidic soil.

[0090] Comparative Example 2:

[0091] A method for preparing a soil remediation agent for acidic soil, the method comprising the following preparation steps:

[0092] (1) 1-amino-1H-imidazole-4,5-

[0093] Diethyl dicarboxylate, hydrazine hydrate and anhydrous ethanol were mixed in a mass ratio of 1:6:45, refluxed at 80°C for 12 hours, naturally cooled to room temperature and then filtered, washed with deionized water and anhydrous ethanol for 4 times respectively, and dried at 70°C for 7 hours to obtain a polymerized monomer;

[0094] (2) Calcite powder, polymerization monomer, benzoquinoline-4,7-

[0095] Diformaldehyde and acetonitrile were mixed in a mass ratio of 1:1.85:1.75:55, ultrasonically dispersed for 2 minutes, and a 12 mol / L acetic acid aqueous solution of 10 times the mass of the calcite powder was added. The mixture was allowed to stand at 25°C for 3 days and then centrifuged. The mixture was washed with acetone and tetrahydrofuran for 4 times respectively, and dried at 60°C for 12 hours to obtain modified calcite.

[0096] (3) Biochar, 2-

[0097] (Bromomethyl)terephthalic acid, chromium nitrate nonahydrate and 90% by volume of N,N-

[0098] The dimethylformamide aqueous solution was mixed at a mass ratio of 1:56:50:1000, reacted at 130°C for 6 hours in a polytetrafluoroethylene-lined autoclave, naturally cooled to room temperature and then filtered, washed with deionized water for 4 times, activated with methanol at 80°C for 24 hours, and dried at 100°C for 7 hours to obtain modified biochar;

[0099] (4) mixing ferric oxide, vinyl trimethoxy alkane and deionized water in a mass ratio of 1:0.7:33.5, stirring at 30°C and 600 rpm for 2 hours, filtering, washing with deionized water for 4 times, and freeze-drying to obtain pre-modified ferric oxide; mixing pre-modified ferric oxide, m-chloroperbenzoic acid and tetrahydrofuran in a mass ratio of 1:2.5:15, ultrasonically dispersed for 25 minutes, stirring at 35°C for 60 minutes, filtering, washing with 10% sodium hydroxide solution and tetrahydrofuran for 4 times, and drying at 60°C for 9 hours to obtain modified ferric oxide;

[0100] (5) Modified calcite, modified biochar and methanol were mixed in a mass ratio of 1:0.1:20, stirred at 25 °C and 350 rpm for 30 min, heated to 50 °C and stirred for 48 h, naturally cooled to room temperature and centrifuged, washed with deionized water for 4 times, dried at 70 °C for 10 h, and modified ferric oxide (0.12 times the mass of modified calcite) was added and mixed to obtain a soil remediation agent for acidic soil.

[0101] Comparative Example 3:

[0102] A method for preparing a soil remediation agent for acidic soil, the method comprising the following preparation steps:

[0103] (1) 1-amino-1H-imidazole-4,5-

[0104] Diethyl dicarboxylate, hydrazine hydrate and anhydrous ethanol were mixed in a mass ratio of 1:6:45, refluxed at 80°C for 12 hours, naturally cooled to room temperature and then filtered, washed with deionized water and anhydrous ethanol for 4 times respectively, and dried at 70°C for 7 hours to obtain a polymerized monomer;

[0105] (2) Calcite powder, polymerization monomer, benzoquinoline-4,7-

[0106] Diformaldehyde and acetonitrile were mixed in a mass ratio of 1:1.85:1.75:55, ultrasonically dispersed for 2 minutes, and a 12 mol / L acetic acid aqueous solution of 10 times the mass of the calcite powder was added. The mixture was allowed to stand at 25°C for 3 days and then centrifuged. The mixture was washed with acetone and tetrahydrofuran for 4 times respectively, and dried at 60°C for 12 hours to obtain modified calcite.

[0107] (3) Mix ferric oxide, vinyl trimethoxy alkane and 2 mg / ml sodium alginate solution in a mass ratio of 1:33.5, stir at 30°C and 600 rpm for 30 min, and use a 1.2 mm syringe pump to drop into a 0.02 mol / L calcium chloride solution that is 16.5 times the mass of ferric oxide. After standing for 1.5 hours, filter, wash with deionized water 4 times, and freeze-dry to obtain pre-modified ferric oxide; mix pre-modified ferric oxide, m-chloroperbenzoic acid and tetrahydrofuran in a mass ratio of 1:2.5:15, ultrasonically disperse for 25 minutes, stir at 35°C for 60 minutes, filter, wash with 10% sodium hydroxide solution and tetrahydrofuran 4 times, and dry at 60°C for 9 hours to obtain modified ferric oxide;

[0108] (4) The modified calcite, biochar and methanol were mixed in a mass ratio of 1:0.1:20, stirred at 25 °C and 350 rpm for 30 min, heated to 50 °C and stirred for 48 h, cooled naturally to room temperature and centrifuged, washed with deionized water for 4 times, dried at 70 °C for 10 h, and modified ferric oxide (0.12 times the mass of the modified calcite) was added and mixed to obtain a soil remediation agent for acidic soil.

[0109] Comparative Example 4:

[0110] A method for preparing a soil remediation agent for acidic soil, the method comprising the following preparation steps:

[0111] (1) Biochar, 2-

[0112] (Bromomethyl)terephthalic acid, chromium nitrate nonahydrate and 90% by volume of N,N-

[0113] The dimethylformamide aqueous solution was mixed at a mass ratio of 1:56:50:1000, reacted at 130°C for 6 hours in a polytetrafluoroethylene-lined autoclave, naturally cooled to room temperature and then filtered, washed with deionized water for 4 times, activated with methanol at 80°C for 24 hours, and dried at 100°C for 7 hours to obtain modified biochar;

[0114] (2) Mix ferric oxide, vinyl trimethoxy alkane and 2 mg / ml sodium alginate solution in a mass ratio of 1:33.5, stir at 30°C and 600 rpm for 30 min, and use a 1.2 mm syringe pump to drop into a 0.02 mol / L calcium chloride solution that is 16.5 times the mass of ferric oxide. After standing for 1.5 hours, filter, wash with deionized water 4 times, and freeze-dry to obtain pre-modified ferric oxide; mix pre-modified ferric oxide, m-chloroperbenzoic acid and tetrahydrofuran in a mass ratio of 1:2.5:15, ultrasonically disperse for 25 minutes, stir at 35°C for 60 minutes, filter, wash with 10% sodium hydroxide solution and tetrahydrofuran 4 times, and dry at 60°C for 9 hours to obtain modified ferric oxide;

[0115] (3) Calcite powder, modified biochar and methanol were mixed in a mass ratio of 1:0.1:20, stirred at 25 °C and 350 rpm for 30 min, heated to 50 °C and stirred for 48 h, cooled naturally to room temperature and centrifuged, washed with deionized water for 4 times, dried at 70 °C for 10 h, and modified ferric oxide (0.12 times the mass of modified calcite) was added and mixed to obtain a soil remediation agent for acidic soil.

[0116] Test Example 1:

[0117] 200 g of coarse dry sand was ground through a 2 mm sieve, 100 mL of a 0.03 mol / L hydrochloric acid solution was added, and the mixture was dried at 50° C. for 24 h to obtain dry acidic sand. The soil was sieved through a 100 mesh sieve, mixed with a cadmium nitrate solution and stirred to 10 mg / kg, passivated for one month in a dark environment at a humidity of 60%, and ground through a 2 mm sieve again to obtain heavy metal contaminated soil. The dry acidic sand and the heavy metal contaminated soil were mixed in a mass ratio of 7:3 to obtain a sand-soil mixture with a pH of 5.

[0118] 1. Persistent acid-base regulation

[0119] Test method: The soil remediation agent for acidic soil obtained in each embodiment and the comparative example was mixed with the sandy soil mixture at a mass ratio of 1:99, cultured at 60% of the field water holding capacity and 25°C for 10 days, rinsed once with 40mL of deionized water, 5g of the sandy soil mixture after elution was taken, put into 25mL of deionized water, magnetically stirred for 24h, centrifuged at 4500rpm for 5min, calibrated the pH meter, immersed the electrode in the solution to be tested, stirred the solution evenly with a glass rod, and measured the pH value (the control sample without adding the soil remediation agent for acidic soil was pH = 4.97); after repeating once a day for 10 days, 5g of the sandy soil mixture after elution was taken again, and the pH value was measured (the control sample without adding the soil remediation agent for acidic soil was pH = 4.38).

[0120] Table 1 below shows the analysis results of the acid-base permanent adjustment properties of the soil remediation agents for acidic soils using Examples 1 to 3 of the present invention and Comparative Examples 1 to 4.

[0121] Table 1

[0122] pH value after 1 wash pH value after 10 washes Example 1 7.59 7.48 Example 2 7.62 7.53 Example 3 7.58 7.49 Comparative Example 1 7.56 7.46 Comparative Example 2 7.58 7.09 Comparative Example 3 7.57 7.47 Comparative Example 4 7.54 5.92

[0123] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 1, it can be found that the soil remediation agent for acidic soil prepared by the present invention has good acid-base long-term adjustment properties.

[0124] By comparison, the pH values ​​of Examples 1, 2, and 3 after 10 washings are higher than those of Comparative Example 4, indicating that hydrazine hydrate is used to convert 1-amino-1H-imidazole-4,5-

[0125] The two ester groups on diethyl dicarboxylate were converted into hydrazide groups by reacting with benzoquinoline-4,7-

[0126] The aldehyde group on diformaldehyde reacts to form a hydrazone bond, which is polymerized and wrapped on the surface of calcite, avoiding the direct release of calcite powder and extending the action time of calcite powder. The hydrazone bond breaks under acidic conditions, promoting the release of calcite powder, enhancing the pH regulating effect of calcite, and improving the acid-base regulation durability of soil remediation agents for acidic soils.

[0127] Test Example 2:

[0128] 200 g of coarse dry sand was ground through a 2 mm sieve, 100 mL of a 0.03 mol / L hydrochloric acid solution was added, and the mixture was dried at 50° C. for 24 h to obtain dry acidic sand. The soil was sieved through a 100 mesh sieve, mixed with a cadmium nitrate solution and stirred to 10 mg / kg, passivated for one month in a dark environment at a humidity of 60%, and ground through a 2 mm sieve again to obtain heavy metal contaminated soil. The dry acidic sand and the heavy metal contaminated soil were mixed in a mass ratio of 7:3 to obtain a sand-soil mixture with a pH of 5.

[0129] 1. Heavy metal complexation

[0130] Test method: The soil remediation agent for acidic soil obtained in each embodiment and comparative example was mixed with a sandy soil mixture at a mass ratio of 1:99, and cultured for 10 days at 60% of the field water holding capacity and 25°C. The cadmium in the soil was extracted with a DTP A (diethylenetriaminepentaacetic acid) extractant. The extract was filtered through a 0.45 μm membrane and the effective cadmium content q1 was determined using an ICPMS7900 inductively coupled plasma mass spectrometer (the soil remediation agent for acidic soil was not added as the control sample q0), and the complexation rate was calculated as (q0-q1) / q0*100%.

[0131] 2. Carbon fixation

[0132] Test method: The acidic soil remediation agent obtained in each embodiment and comparative example was mixed with a sandy soil mixture in a mass ratio of 1:99, and the carbon content C0 was determined using a VARIOELIII elemental analyzer. The mixture was cultured for 10 days at 60% of the field water holding capacity and 25°C, and the carbon content C1 was tested again. The carbon content was calculated as C1 / C0*100%.

[0133] 3. Water retention

[0134] Test method: The acidic soil remediation agent obtained in each embodiment and comparative example was mixed with a sandy soil mixture in a mass ratio of 1:99 and put into a nylon mesh bag. The total weight of the soil and the nylon bag was measured as W0. The bag was fully watered to reach saturation. The bag was hung for 24 hours until no water dripped out. The total weight of the soil and the nylon bag was measured again as W1. The water holding capacity of the soil was calculated as (W1-W0) / W0*100%.

[0135] Table 2 below shows the analysis results of the heavy metal complexing, carbon fixation and water retention of the soil remediation agents for acidic soil using Examples 1 to 3 of the present invention and Comparative Examples 1 to 4.

[0136] Table 2

[0137]

[0138]

[0139] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 2, it can be found that the soil remediation agent for acidic soil prepared by the present invention has good heavy metal complexing, carbon fixation and water retention properties.

[0140] By comparison, the carbon content of Examples 1, 2, and 3 is higher than that of Comparative Example 1, indicating that the carbon-carbon double bonds grafted on the surface of ferric oxide are oxidized by m-chloroperbenzoic acid to form epoxy groups, and the epoxy groups are used to react with carbon dioxide to reduce the release of carbon dioxide and improve the carbon fixation of the soil remediation agent for acidic soils.

[0141] By comparison, the water holding rates of Examples 1, 2, and 3 are higher than those of Comparative Example 2, indicating that the use of sodium alginate to complex calcium ions to encapsulate ferric oxide forms a gel-like substance between soil particles, promotes the formation of soil aggregate structure, and improves the water retention of the soil remediation agent for acidic soil.

[0142] By comparison, the complexation rate and carbon content of Examples 1, 2, and 3 are higher than that of Comparative Example 3, which illustrates that a metal-organic skeleton is formed by combining 2-(bromomethyl)terephthalic acid with chromium nitrate nonahydrate to form a metal-organic skeleton, increase the specific surface area and active sites, adsorb and coordinate heavy metal ions, and improve the heavy metal complexation of the soil remediation agent for acidic soils; at the same time, the bromine on the metal-organic skeleton in the modified biochar reacts with the imidazole ring on the modified calcite to undergo a quaternary ammonium reaction, and the bromine imidazole salt can catalyze the cyclization reaction of the epoxy group with carbon dioxide, thereby enhancing the carbon fixation of the soil remediation agent for acidic soils.

[0143] By comparison, the complexation rate and carbon content of Examples 1, 2, and 3 are higher than those of Comparative Example 4, which shows that 1-amino-1H-imidazole-4,5-

[0144] The two ester groups on diethyl dicarboxylate were converted into hydrazide groups by reacting with benzoquinoline-4,7-

[0145] The aldehyde group on diformaldehyde reacts to form a hydrazone bond, which is polymerized and wrapped on the surface of calcite. The nitrogen atom on benzoquinoline carries a lone pair of electrons and can form a coordination bond with heavy metal ions, thereby improving the heavy metal complexing property of the soil remediation agent for acidic soils. At the same time, the imidazole ring on the modified calcite reacts with the bromine on the metal organic framework in the modified biochar to form a quaternary ammonium reaction, and the bromine imidazole salt can catalyze the cyclization reaction of the epoxy group with carbon dioxide, thereby enhancing the carbon fixation property of the soil remediation agent for acidic soils.

[0146] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A soil remediation agent for acidic soil, characterized in that: The soil remediation agent for acidic soil is obtained by mixing modified calcite, modified biochar and modified ferric oxide; The modified calcite is composed of 1-amino-1H-imidazole-4,5- After the polymerization monomer is obtained by reacting diethyl dicarboxylate with hydrazine hydrate, it is mixed with calcite powder and benzoquinoline-4,7-dicarboxaldehyde to obtain a polymerization monomer; The modified biochar is composed of biochar, 2- It is prepared by mixing (bromomethyl)terephthalic acid and chromium nitrate nonahydrate; The modified ferric oxide is prepared by mixing ferric oxide powder, vinyl trimethoxyalkane, sodium alginate and calcium chloride and then oxidizing with meta-chloroperbenzoic acid.

2. A method for preparing a soil remediation agent for acidic soil, characterized in that: The method comprises the following preparation steps: (1) 1-amino-1H-imidazole-4,5- Diethyl dicarboxylate, hydrazine hydrate and anhydrous ethanol are mixed in a mass ratio, cooled to room temperature after refluxing, filtered, washed and dried to obtain a polymerized monomer; (2) Calcite powder, polymerization monomer, benzoquinoline-4,7- Diformaldehyde and acetonitrile are mixed in a mass ratio, dispersed by ultrasonication, and 11-13 mol / L acetic acid aqueous solution is added, the mixture is allowed to stand and then centrifuged, washed and dried to obtain modified calcite; (3) Biochar, 2-(bromomethyl)terephthalic acid, chromium nitrate nonahydrate and N,N- The dimethylformamide aqueous solution is mixed, reacted in a polytetrafluoroethylene-lined autoclave, cooled to room temperature, filtered and washed, activated with methanol, and dried to obtain modified biochar; (4) mixing ferric oxide, vinyl trimethoxy alkane and sodium alginate solution, dripping into calcium chloride solution with a syringe pump, filtering and washing after standing, and freeze-drying to obtain pre-modified ferric oxide; mixing pre-modified ferric oxide, m-chloroperbenzoic acid and tetrahydrofuran, filtering after ultrasonic dispersion, washing and drying to obtain modified ferric oxide; (5) The modified calcite, modified biochar and methanol are mixed, cooled to room temperature after the reaction, centrifuged, washed and dried, and modified ferric oxide is added and mixed to obtain a soil remediation agent for acidic soil.

3. The method for preparing a soil remediation agent for acidic soil according to claim 2, characterized in that: The specific preparation process of the polymer monomer in step (1) is as follows: 1-amino-1H-imidazole-4,5-dicarboxylic acid diethyl ester, hydrazine hydrate and anhydrous ethanol are mixed in a mass ratio of 1:(5-7):(44-46), refluxed at 75-85° C. for 11-13 hours, naturally cooled to room temperature and then filtered, washed with deionized water and anhydrous ethanol for 3-5 times respectively, and dried at 65-75° C. for 6-8 hours.

4. The method for preparing a soil remediation agent for acidic soil according to claim 2, characterized in that: The specific preparation process of the modified calcite in step (2) is as follows: calcite powder, polymerization monomer, benzoquinoline-4,7- Diformaldehyde and acetonitrile are mixed in a mass ratio of 1: (1.8-1.9): (1.7-1.8): (50-60), and ultrasonically dispersed for 1-3 min. Add 11-13 mol / L acetic acid aqueous solution which is 9-11 times the mass of calcite powder, and stand at 20-30°C for 2-4 days before centrifugation. Wash with acetone and tetrahydrofuran for 3-5 times respectively, and dry at 55-65°C for 11-13 h.

5. The method for preparing a soil remediation agent for acidic soil according to claim 2, characterized in that: The specific preparation process of the modified biochar in step (3) is as follows: biochar, 2- (Bromomethyl)terephthalic acid, chromium nitrate nonahydrate and 85% to 95% by volume of N,N- The dimethylformamide aqueous solution is mixed in a mass ratio of 1: (55-57): (45-55): (950-1050), reacted at 125-135°C in a polytetrafluoroethylene-lined autoclave for 5-7 hours, naturally cooled to room temperature and then filtered, washed with deionized water for 3-5 times, activated with methanol at 75-85°C for 23-25 ​​hours, and dried at 95-105°C for 6-8 hours.

6. The method for preparing a soil remediation agent for acidic soil according to claim 2, characterized in that: The specific preparation process of the pre-modified ferric oxide in step (4) is as follows: ferric oxide, vinyl trimethoxyalkane and 1-3 mg / ml sodium alginate solution are mixed in a mass ratio of 1:(0.6-0.8):(33-34), stirred at 25-35° C. and 500-700 rpm for 25-35 min, and dripped into a 0.01-0.03 mol / L calcium chloride solution which is 16-17 times the mass of ferric oxide using a 1.1-1.3 mm syringe pump, filtered after standing for 1-2 h, washed with deionized water 3-5 times, and freeze-dried.

7. The method for preparing a soil remediation agent for acidic soil according to claim 2, characterized in that: The specific preparation process of the modified ferric oxide in step (4) is as follows: pre-modified ferric oxide, meta-chloroperbenzoic acid and tetrahydrofuran are mixed in a mass ratio of 1: (2.4-2.6): (14-16), ultrasonically dispersed for 20-30 min, stirred at 30-40 ° C for 55-65 min and then filtered, washed with 9%-11% sodium hydroxide solution and tetrahydrofuran for 3-5 times respectively, and dried at 55-65 ° C for 8-10 h.

8. The method for preparing a soil remediation agent for acidic soil according to claim 2, characterized in that: The specific preparation process of the soil remediation agent for acidic soil in step (5) is as follows: modified calcite, modified biochar and methanol are mixed in a mass ratio of 1: (0.09-0.11): (19-21), stirred at 20-30°C and 300-400 rpm for 25-35 min, heated to 45-55°C and continued to stir for 47-49 h, naturally cooled to room temperature and then centrifuged, washed with deionized water for 3-5 times, dried at 65-75°C for 9-11 h, and modified ferric oxide of 0.11-0.13 times the mass of modified calcite is added and mixed.

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