A kind of persistent saline-alkali land organic pollutant contaminated soil remediation material and remediation method

Abstract

The present invention belongs to the technical field of organic pollution control, and relates to a material and method for repairing soil contaminated by persistent saline-alkali organic pollutants. The bamboo charcoal and graphene oxide modified soybean straw biochar of the present invention are mixed with an enzyme solution, and the prepared repair material under the action of a cross-linking agent can significantly degrade the content of nitrochlorobenzene, trichloroethylene and / or polycyclic aromatic hydrocarbons in organic polluted soil. The repair material of the present invention has a good repair effect on organic pollutants in contaminated soil, and can be applied to saline-alkali soils with various organic pollution levels, with good degradation effect, and has a high application prospect in the repair of soil organic pollutants.

Description

Technical Field

[0001] The invention belongs to the technical field of organic pollution control, and relates to a material and a method for repairing soil contaminated by persistent saline-alkali organic pollutants. Background Art

[0002] The sources of soil pollution are mainly human domestic waste, fertilizers and pesticides, industrial wastewater, waste liquid and industrial solid waste, among which industrial pollution accounts for the majority. Pollutants that pollute soil are mainly divided into three categories: inorganic pollutants, organic pollutants and radioactive pollutants. Inorganic pollutants mainly include heavy metal pollutants, acid, alkali and salt pollutants; organic pollutants mainly include polycyclic aromatic hydrocarbon pollutants and chlorinated hydrocarbon pollutants. Organic pollutants are the most serious pollutants to soil and groundwater, and have become the main source of soil and groundwater pollution today.

[0003] Contaminated soil remediation can be divided into physical, chemical and biological remediation technologies according to the principles of remediation technology. For contaminated soil, it can be divided into two categories: in-situ and ex-situ remediation technologies.

[0004] In-situ soil remediation technology is to repair and treat the contaminated soil in the area without destroying the basic structure of the soil. This remediation method does not require digging and transporting soil, and is easy to operate on site. Currently, common in-situ soil remediation technologies include soil vapor extraction technology, in-situ chemical leaching, in-situ chemical oxidation technology, in-situ chemical solidification / stabilization, in-situ biological ventilation technology, in-situ microbial remediation technology, in-situ plant remediation technology, electric remediation technology, etc.

[0005] The choice of remediation technology mainly depends on the soil characteristics of the remediation site and the characteristics of the pollutants in the site. At present, it is rare to rely on a single remediation technology to complete the remediation of soil or groundwater pollution. Often, multiple remediation technologies are used in combination to improve remediation efficiency, shorten remediation cycles, and reduce remediation costs.

[0006] Biochar is a product formed by thermal cracking of biomass under anaerobic conditions. Biochar particles are small, finely distributed, and light in texture. It is a black porous solid whose main components are carbon and oxygen. Biochar has the characteristics of looseness, large specific surface area, and a large amount of negative charge on the surface. These characteristics make biochar have good adsorption properties and it is used as a soil structure improver or a soil pollution repair agent. Summary of the invention

[0007] In view of this, the purpose of the present invention is to provide a persistent saline-alkali land organic pollutant contaminated soil remediation material and remediation method, the saline-alkali land organic pollutant soil remediation material can effectively remove nitrochlorobenzene, trichloroethylene and polycyclic aromatic hydrocarbons in saline-alkali soil, and effectively improve the organic polluted soil environment.

[0008] To achieve the above objectives, this application adopts the following technical solutions:

[0009] A persistent saline-alkali soil organic pollutant contaminated soil remediation material, the preparation method is as follows:

[0010] S1 Bamboo Charcoal Preparation

[0011] The bamboo was cleaned, air-dried, crushed with a grinder, pyrolyzed at 1000°C in a muffle furnace under a nitrogen atmosphere, cooled to room temperature, taken out, ground and sieved to obtain bamboo charcoal;

[0012] Preparation of S2 modified biochar

[0013] Cut soybean straw into small pieces, wash them and put them into an oven, dry them at 70°C for 12 hours, and then crush them through a 10-mesh sieve to obtain soybean straw powder; mix the soybean straw powder with graphene oxide, pyrolyze them at 700-750°C for 1-2 hours under nitrogen protection to obtain mixed biochar; soak the mixed biochar in potassium permanganate solution, pyrolyze them at 700-750°C for 1-2 hours to obtain graphene oxide modified biochar;

[0014] S3 modified biochar adsorption enzyme solution

[0015] The bamboo charcoal, graphene oxide modified biochar and enzyme solution were uniformly mixed in a mass ratio of 2:2:5 and subjected to constant temperature adsorption to obtain a modified biochar composite enzyme solution;

[0016] The enzyme solution contains cellulase, xylanase, urease, amylase and protease, and the mass ratio of the cellulase, xylanase, urease, amylase and protease is (1-3): (2-4): (1-3): (3-5): 1;

[0017] S4 crosslink

[0018] NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution are mixed to obtain a mixed solvent, which is stirred and cross-linked in an ice water bath, then moved to room temperature for drying, rinsed with clean water, and dried to obtain an organic contaminated soil remediation material; the mass ratio of NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution is 2:3:10:20, the concentration of NN-methylenebisacrylamide is 0.45 mol / L, and the concentration of sodium alginate is 0.85 mol / L.

[0019] Preferably, the step S1 is to wash the bamboo, air dry it naturally for 2 days, crush it mechanically with a grinder for 20 minutes, heat it to 1000°C at a heating rate of 10°C / min in a muffle furnace under a nitrogen atmosphere, and keep it for pyrolysis for 2 hours, cool it to room temperature, take it out, grind it through a 100-mesh sieve, and obtain bamboo charcoal.

[0020] Preferably, in step S2, the mass ratio of the soybean straw powder to graphene oxide is 250-270:1; the mass ratio of the mixed biochar to the potassium permanganate solution is (1-2):20, and the mass concentration of the potassium permanganate solution is 5%.

[0021] Further preferably, in step S2, the mass ratio of the soybean straw powder to graphene oxide is 260:1; the mass ratio of the mixed biochar to the potassium permanganate solution is 1.5:20, and the mass concentration of the potassium permanganate solution is 5%.

[0022] Preferably, in step S3, the adsorption temperature is 15-20° C. and the adsorption time is 3-3.5 hours.

[0023] Preferably, in step S3, the mass ratio of cellulase, xylanase, urease, amylase and protease is 2:3:2:4:1.

[0024] Preferably, in step S4, the cross-linking is carried out by stirring in an ice water bath for 10-15 minutes, drying at room temperature for 10-15 minutes, and rinsing with clean water for 2-4 times.

[0025] Further preferably, in step S4, the cross-linking is carried out by stirring in an ice water bath for 12 minutes, drying at room temperature for 12 minutes, and rinsing with clean water for 3 times.

[0026] The graphene oxide modified biochar prepared by the present invention is used as a remover and catalytic decomposition agent to treat organic pollution in saline-alkali soil. Through comparative characterization analysis and removal and catalytic decomposition effect research, it is found that soybean straw biochar has strong redox ability, rich surface functional groups and large specific surface area, and has strong removal and catalytic decomposition ability for organic pollution.

[0027] Graphene oxide modified biochar increases the number of oxygen-containing functional groups on the surface of soybean straw biochar, increases the adsorption active sites, has a large specific surface area, good air permeability and water permeability, and strong adsorption and chelating abilities. It can increase the organic matter content in the soil and improve the structure and porosity of the soil.

[0028] The graphene oxide modified biochar material of the present invention has the adsorption properties of both biochar and graphene oxide, has the advantages of large adsorption capacity, high adsorption efficiency, etc., and has a good adsorption and removal effect on organic pollution in the soil.

[0029] The graphene oxide modified biochar of the present invention is used as an enzyme fixative to fix the enzyme, which not only improves the specific surface area, the number of active functional groups and the adsorption and retention capacity of pollutants of the biochar, but also increases the attachment area of ​​the enzyme to be fixed, enhances the activity of the enzyme, enhances the degradation or conversion of organic pollution, improves the fertility of the repaired soil, and achieves the purpose of efficiently repairing organically contaminated soil.

[0030] The repair material of the present invention has a better effect on removing organic pollution by adding two kinds of biochar than adding only one kind of biochar.

[0031] After the graphene oxide modified biochar of the present invention is mixed with enzyme solution, they are grafted and cross-linked together through free radical reaction under the action of a cross-linking agent to form a three-dimensional network polymer, and the enzyme solution is loaded on the polymer to remove organic pollution while improving the soil quality of saline-alkali land.

[0032] The present invention provides application of the persistent saline-alkali land organic pollutant contaminated soil restoration material obtained by the above preparation method in in-situ restoration of soil organic pollution.

[0033] Preferably, the organic pollution is nitrochlorobenzene, trichloroethylene and / or polycyclic aromatic hydrocarbons pollution.

[0034] Beneficial effects achieved by the present invention:

[0035] (1) The graphene oxide modified biochar prepared by the present invention increases the number of oxygen-containing functional groups on the surface of soybean straw biochar, increases the adsorption active sites, has a large specific surface area, good air permeability and water permeability, has the advantages of large adsorption capacity, high adsorption efficiency, etc., and has a good adsorption and removal effect on organic pollution in the soil. Adding two biochars has a better removal effect on polycyclic aromatic hydrocarbons than adding only one biochar. After the graphene oxide modified biochar of the present invention is mixed with the enzyme solution, it is grafted and cross-linked together through free radical reaction under the action of a cross-linking agent to form a three-dimensional network polymer, and the enzyme solution is loaded on the polymer, which not only increases the specific surface area, the number of active functional groups and the adsorption and retention capacity of pollutants of the biochar, but also increases the attachment area of ​​the enzyme to be fixed, enhances the activity of the enzyme, and enhances the degradation or conversion of organic pollution.

[0036] (2) The remediation material prepared by mixing the bamboo charcoal and the graphene oxide-modified soybean straw biochar with the enzyme solution under the action of a crosslinking agent can significantly degrade nitrochlorobenzene, trichloroethylene and / or polycyclic aromatic hydrocarbons in organic contaminated soil. The organic contaminated soil remediation material of the present invention has a good remediation effect on high-concentration organic pollutants in contaminated soil, is suitable for saline-alkali soils with various organic pollution levels, has a good degradation effect, and has a high application prospect in the remediation of soil organic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for the specific implementation methods are briefly introduced below.

[0038] Figure 1 This is the removal effect of the organic contaminated soil remediation material of the present invention on organic pollution.

[0039] Figure 2This is the removal effect of the organic contaminated soil remediation material of the present invention on phenanthrene.

[0040] Figure 3 The present invention shows the removal effect of the organic contaminated soil remediation material on pyrene. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. The test reagents used in the following embodiments, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0042] Example 1: Saline-alkali land organic contaminated soil remediation material and preparation method thereof

[0043] S1 Bamboo Charcoal Preparation

[0044] After cleaning the bamboo, air-dry it for 2 days, crush it mechanically with a grinder for 20 minutes, heat it to 1000°C at a heating rate of 10°C / min in a muffle furnace under a nitrogen atmosphere, and keep it for pyrolysis for 2 hours. After cooling to room temperature, take it out, grind it through a 100-mesh sieve, and obtain bamboo charcoal.

[0045] Preparation of S2 modified biochar

[0046] Cut soybean straw into small pieces, wash them and put them into an oven, dry them at 70°C for 12 hours, and then crush them through a 10-mesh sieve to obtain soybean straw powder; mix the soybean straw powder and graphene oxide at a mass ratio of 260:1, pyrolyze them at 750°C for 2 hours under nitrogen protection to obtain mixed biochar; soak the mixed biochar in a potassium permanganate solution with a mass concentration of 5%, mix them at a mass ratio of 1.5:20, and pyrolyze them at 750°C for 2 hours to obtain graphene oxide modified biochar;

[0047] S3 modified biochar adsorption enzyme solution

[0048] The bamboo charcoal, graphene oxide modified biochar and the enzyme solution composed of cellulase, xylanase, urease, amylase and protease in a mass ratio of 2:3:2:4:1 were uniformly mixed in a mass ratio of 2:2:5 for constant temperature adsorption at a temperature of 20°C for 3 hours to obtain the modified biochar composite enzyme solution;

[0049] S4 crosslink

[0050] NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution are mixed to obtain a mixed solvent, which is stirred and cross-linked in an ice water bath for 15 minutes, dried at room temperature for 10 minutes, rinsed with clean water three times, and dried to obtain an organic contaminated soil remediation material; the mass ratio of NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution is 2:3:10:20, the concentration of NN-methylenebisacrylamide is 0.45 mol / L, and the concentration of sodium alginate is 0.85 mol / L.

[0051] Example 2: Saline-alkali land organic contaminated soil remediation material and preparation method thereof

[0052] S1 Bamboo Charcoal Preparation

[0053] After cleaning the bamboo, air-dry it for 2 days, crush it mechanically with a grinder for 20 minutes, heat it to 1000°C at a heating rate of 10°C / min in a muffle furnace under a nitrogen atmosphere, and keep it for pyrolysis for 2 hours. After cooling to room temperature, take it out, grind it through a 100-mesh sieve, and obtain bamboo charcoal.

[0054] Preparation of S2 modified biochar

[0055] Cut soybean straw into small pieces, wash them and put them into an oven, dry them at 70°C for 12 hours, and then crush them through a 10-mesh sieve to obtain soybean straw powder; mix the soybean straw powder and graphene oxide at a mass ratio of 270:1, pyrolyze them at 700°C for 2 hours under nitrogen protection to obtain mixed biochar; soak the mixed biochar in a potassium permanganate solution with a mass concentration of 5%, mix them at a mass ratio of 2:20, pyrolyze them at 700°C for 2 hours, and obtain graphene oxide modified biochar;

[0056] S3 modified biochar adsorption enzyme solution

[0057] The bamboo charcoal, graphene oxide modified biochar and an enzyme solution composed of cellulase, xylanase, urease, amylase and protease in a mass ratio of 2:4:2:5 were uniformly mixed and adsorbed at a constant temperature at a temperature of 15°C for 3.5 hours to obtain a modified biochar composite enzyme solution;

[0058] S4 crosslink

[0059] NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution are mixed to obtain a mixed solvent, the mixture is stirred and cross-linked in an ice water bath for 15 minutes, dried at room temperature for 15 minutes, rinsed twice with clean water, and dried to obtain an organic contaminated soil remediation material; the mass ratio of NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution is 2:3:10:20, the concentration of NN-methylenebisacrylamide is 0.45 mol / L, and the concentration of sodium alginate is 0.85 mol / L.

[0060] Example 3: Saline-alkali land organic contaminated soil remediation material and preparation method thereof

[0061] S1 Bamboo Charcoal Preparation

[0062] After cleaning the bamboo, air-dry it for 2 days, crush it mechanically with a grinder for 20 minutes, heat it to 1000°C at a heating rate of 10°C / min in a muffle furnace under a nitrogen atmosphere, and keep it for pyrolysis for 2 hours. After cooling to room temperature, take it out, grind it through a 100-mesh sieve, and obtain bamboo charcoal.

[0063] Preparation of S2 modified biochar

[0064] Cut soybean straw into small pieces, wash them and put them into an oven, dry them at 70°C for 12 hours, and then crush them through a 10-mesh sieve to obtain soybean straw powder; mix the soybean straw powder and graphene oxide at a mass ratio of 250:1, pyrolyze them at 700°C for 2 hours under nitrogen protection to obtain mixed biochar; soak the mixed biochar in a potassium permanganate solution with a mass concentration of 5%, mix them at a mass ratio of 2:20, pyrolyze them at 700°C for 2 hours, and obtain graphene oxide modified biochar;

[0065] S3 modified biochar adsorption enzyme solution

[0066] The bamboo charcoal, graphene oxide modified biochar and the enzyme solution composed of cellulase, xylanase, urease, amylase and protease in a mass ratio of 1:2:1:5:1 were uniformly mixed and adsorbed at a constant temperature of 20°C for 3 hours to obtain the modified biochar composite enzyme solution;

[0067] S4 crosslink

[0068] NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution are mixed to obtain a mixed solvent, which is stirred and cross-linked in an ice water bath for 12 minutes, dried at room temperature for 15 minutes, rinsed twice with clean water, and dried to obtain an organic contaminated soil remediation material; the mass ratio of NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution is 2:3:10:20, the concentration of NN-methylenebisacrylamide is 0.45 mol / L, and the concentration of sodium alginate is 0.85 mol / L.

[0069] Example 4: Saline-alkali land organic contaminated soil remediation material and preparation method thereof

[0070] S1 Bamboo Charcoal Preparation

[0071] After cleaning the bamboo, air-dry it for 2 days, crush it mechanically with a grinder for 20 minutes, heat it to 1000°C at a heating rate of 10°C / min in a muffle furnace under a nitrogen atmosphere, and keep it for pyrolysis for 2 hours. After cooling to room temperature, take it out, grind it through a 100-mesh sieve, and obtain bamboo charcoal.

[0072] Preparation of S2 modified biochar

[0073] Cut soybean straw into small pieces, wash them and put them into an oven, dry them at 70°C for 12 hours, and then grind them through a 10-mesh sieve to obtain soybean straw powder; mix the soybean straw powder and graphene oxide at a mass ratio of 270:1, pyrolyze them at 750°C for 1 hour under nitrogen protection to obtain mixed biochar; soak the mixed biochar in a potassium permanganate solution with a mass concentration of 5%, mix them at a mass ratio of 1:20, pyrolyze them at 750°C for 1 hour, and obtain graphene oxide modified biochar;

[0074] S3 modified biochar adsorption enzyme solution

[0075] The bamboo charcoal, graphene oxide modified biochar and the enzyme solution composed of cellulase, xylanase, urease, amylase and protease in a mass ratio of 3:4:3:3:1 were uniformly mixed in a mass ratio of 2:2:5 for constant temperature adsorption at a temperature of 15°C for 3.5 hours to obtain the modified biochar composite enzyme solution;

[0076] S4 crosslink

[0077] NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution are mixed to obtain a mixed solvent, the mixture is stirred and cross-linked in an ice water bath for 15 minutes, dried at room temperature for 10 minutes, rinsed with clean water 4 times, and dried to obtain an organic contaminated soil remediation material; the mass ratio of NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution is 2:3:10:20, the concentration of NN-methylenebisacrylamide is 0.45 mol / L, and the concentration of sodium alginate is 0.85 mol / L.

[0078] Example 5: Saline-alkali land organic contaminated soil remediation material and preparation method thereof

[0079] S1 Bamboo Charcoal Preparation

[0080] After cleaning the bamboo, air-dry it for 2 days, crush it mechanically with a grinder for 20 minutes, heat it to 1000°C at a heating rate of 10°C / min in a muffle furnace under a nitrogen atmosphere, and keep it for pyrolysis for 2 hours. After cooling to room temperature, take it out, grind it through a 100-mesh sieve, and obtain bamboo charcoal.

[0081] Preparation of S2 modified biochar

[0082] Cut soybean straw into small pieces, wash them and put them into an oven, dry them at 70°C for 12 hours, and then crush them through a 10-mesh sieve to obtain soybean straw powder; mix the soybean straw powder and graphene oxide at a mass ratio of 270:1, pyrolyze them at 700°C for 1 hour under nitrogen protection to obtain mixed biochar; soak the mixed biochar in a potassium permanganate solution with a mass concentration of 5%, mix them at a mass ratio of 1.8:20, and pyrolyze them at 750°C for 2 hours to obtain graphene oxide modified biochar;

[0083] S3 modified biochar adsorption enzyme solution

[0084] The bamboo charcoal, graphene oxide modified biochar and the enzyme solution composed of cellulase, xylanase, urease, amylase and protease in a mass ratio of 2:4:3:3:1 were uniformly mixed in a mass ratio of 2:2:5 for constant temperature adsorption at a temperature of 15°C for 3.5 hours to obtain the modified biochar composite enzyme solution;

[0085] S4 crosslink

[0086] NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution are mixed to obtain a mixed solvent, the mixture is stirred and cross-linked in an ice water bath for 15 minutes, dried at room temperature for 10 minutes, rinsed twice with clean water, and dried to obtain an organic contaminated soil remediation material; the mass ratio of NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution is 2:3:10:20, the concentration of NN-methylenebisacrylamide is 0.45 mol / L, and the concentration of sodium alginate is 0.85 mol / L.

[0087] Comparative Example 1: Saline-alkali land organic contaminated soil remediation material and preparation method thereof

[0088] Compared with Example 1, the difference is that no bamboo charcoal is added.

[0089] S1 Modified Biochar Preparation

[0090] Cut soybean straw into small pieces, wash them and put them into an oven, dry them at 70°C for 12 hours, and then crush them through a 10-mesh sieve to obtain soybean straw powder; mix the soybean straw powder and graphene oxide at a mass ratio of 260:1, pyrolyze them at 750°C for 2 hours under nitrogen protection to obtain mixed biochar; soak the mixed biochar in a potassium permanganate solution with a mass concentration of 5%, mix them at a mass ratio of 1.5:20, and pyrolyze them at 750°C for 2 hours to obtain graphene oxide modified biochar;

[0091] S2 modified biochar adsorption enzyme solution

[0092] The graphene oxide modified biochar and the enzyme solution composed of cellulase, xylanase, urease, amylase and protease in a mass ratio of 2:3:2:4:1 were uniformly mixed in a mass ratio of 2:5 for constant temperature adsorption at a temperature of 20°C for 3 hours to obtain the modified biochar composite enzyme solution;

[0093] S3 crosslink

[0094] NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution are mixed to obtain a mixed solvent, which is stirred and cross-linked in an ice water bath for 15 minutes, dried at room temperature for 10 minutes, rinsed with clean water three times, and dried to obtain an organic contaminated soil remediation material; the mass ratio of NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution is 2:3:10:20, the concentration of NN-methylenebisacrylamide is 0.45 mol / L, and the concentration of sodium alginate is 0.85 mol / L.

[0095] Comparative Example 2: Saline-alkali land organic contaminated soil remediation material and preparation method thereof

[0096] Compared with Example 1, the difference is that the soybean straw biochar is not modified.

[0097] S1 Bamboo Charcoal Preparation

[0098] After cleaning the bamboo, air-dry it for 2 days, crush it mechanically with a grinder for 20 minutes, heat it to 1000°C at a heating rate of 10°C / min in a muffle furnace under a nitrogen atmosphere, and keep it for pyrolysis for 2 hours. After cooling to room temperature, take it out, grind it through a 100-mesh sieve, and obtain bamboo charcoal.

[0099] S2 Soybean Straw Biochar Preparation

[0100] Cut the soybean straw into small pieces, wash them and put them into an oven, dry them at 70°C for 12 hours, and then grind them through a 10-mesh sieve to obtain soybean straw powder; pyrolyze the soybean straw powder at 750°C for 4 hours under nitrogen protection to obtain soybean straw biochar;

[0101] S3 modified biochar adsorption enzyme solution

[0102] Bamboo charcoal, soybean straw biochar and enzyme solution composed of cellulase, xylanase, urease, amylase and protease in a mass ratio of 2:3:2:4:1 were uniformly mixed in a mass ratio of 2:2:5 for constant temperature adsorption at a temperature of 20°C for 3 hours to obtain a biochar composite enzyme solution;

[0103] S4 crosslink

[0104] NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution are mixed to obtain a mixed solvent, which is stirred and cross-linked in an ice water bath for 15 minutes, dried at room temperature for 10 minutes, rinsed with clean water three times, and dried to obtain an organic contaminated soil remediation material; the mass ratio of NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution is 2:3:10:20, the concentration of NN-methylenebisacrylamide is 0.45 mol / L, and the concentration of sodium alginate is 0.85 mol / L.

[0105] Comparative Example 3: Saline-alkali land organic contaminated soil remediation material and preparation method thereof

[0106] Compared with Example 1, the difference is that in the soybean straw biochar modification treatment, no potassium permanganate solution is used for soaking.

[0107] S1 Bamboo Charcoal Preparation

[0108] After cleaning the bamboo, air-dry it for 2 days, crush it mechanically with a grinder for 20 minutes, heat it to 1000°C at a heating rate of 10°C / min in a muffle furnace under a nitrogen atmosphere, and keep it for pyrolysis for 2 hours. After cooling to room temperature, take it out, grind it through a 100-mesh sieve, and obtain bamboo charcoal.

[0109] Preparation of S2 modified biochar

[0110] Cut soybean straw into small pieces, wash them and put them into an oven, dry them at 70°C for 12 hours, and then grind them through a 10-mesh sieve to obtain soybean straw powder; mix the soybean straw powder and graphene oxide at a mass ratio of 260:1, pyrolyze them at 750°C for 2 hours under nitrogen protection to obtain graphene-modified biochar;

[0111] S3 modified biochar adsorption enzyme solution

[0112] The bamboo charcoal and graphene-modified biochar were uniformly mixed with an enzyme solution composed of cellulase, xylanase, urease, amylase and protease in a mass ratio of 2:3:2:4:1 and a mass ratio of 2:2:5 for constant temperature adsorption at a temperature of 20°C for 3 hours to obtain a modified biochar composite enzyme solution;

[0113] S4 crosslink

[0114] NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution are mixed to obtain a mixed solvent, which is stirred and cross-linked in an ice water bath for 15 minutes, dried at room temperature for 10 minutes, rinsed with clean water three times, and dried to obtain an organic contaminated soil remediation material; the mass ratio of NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution is 2:3:10:20, the concentration of NN-methylenebisacrylamide is 0.45 mol / L, and the concentration of sodium alginate is 0.85 mol / L.

[0115] Comparative Example 4: Saline-alkali land organic contaminated soil remediation material and preparation method thereof

[0116] Compared with Example 1, the difference is that peanut shell biochar is used instead of soybean straw biochar, and the composition and proportion of the enzyme solution are different.

[0117] S1 Bamboo Charcoal Preparation

[0118] After cleaning the bamboo, air-dry it for 2 days, crush it mechanically with a grinder for 20 minutes, heat it to 1000°C at a heating rate of 10°C / min in a muffle furnace under a nitrogen atmosphere, and keep it for pyrolysis for 2 hours. After cooling to room temperature, take it out, grind it through a 100-mesh sieve, and obtain bamboo charcoal.

[0119] Preparation of S2 modified biochar

[0120] Wash the peanut shells and put them into an oven, dry them at 65°C for 8 hours, and then crush them through a 10-mesh sieve to obtain peanut shell powder; mix the peanut shell powder and graphene oxide at a mass ratio of 200:1, pyrolyze them at 750°C for 2 hours under nitrogen protection to obtain mixed biochar; soak the mixed biochar in a potassium permanganate solution with a mass concentration of 5%, mix them at a mass ratio of 1.5:20, pyrolyze them at 750°C for 2 hours, and obtain graphene oxide modified peanut shell biochar;

[0121] S3 modified biochar adsorption enzyme solution

[0122] Bamboo charcoal, graphene oxide modified peanut shell biochar and enzyme solution composed of cellulase, xylanase, urease and protease in a mass ratio of 2:3:2:1 were uniformly mixed and adsorbed at a constant temperature of 20°C for 3 hours to obtain a modified biochar composite enzyme solution.

[0123] S4 crosslink

[0124] NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution are mixed to obtain a mixed solvent, which is stirred and cross-linked in an ice water bath for 15 minutes, dried at room temperature for 10 minutes, rinsed with clean water three times, and dried to obtain an organic contaminated soil remediation material; the mass ratio of NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution is 2:3:10:20, the concentration of NN-methylenebisacrylamide is 0.45 mol / L, and the concentration of sodium alginate is 0.85 mol / L.

[0125] Verification Example 1 Testing the removal ability of the organic contaminated soil remediation material of the present invention on polycyclic aromatic hydrocarbons

[0126] Performance test of removing organic pollution in saline-alkali soil: Prepare saline-alkali soil containing nitrochlorobenzene and trichloroethylene, where the content of both pollutants in the contaminated soil is 6 mg / g, and place the repair materials prepared in Examples 1-3 and Comparative Example 4 in the contaminated soil respectively, where the weight of each group of contaminated soil is 700 g, and the mass ratio of the repair material to the contaminated soil is 1:80. Place at room temperature for 60 days, and test the concentration of the contaminated soil with a gas chromatograph. Record the average removal rate of nitrochlorobenzene and trichloroethylene pollutants within 60 days, and the results are as follows: Figure 1 shown.

[0127] Polycyclic aromatic hydrocarbons (PAHs) refer to a class of organic compounds with two or more benzene rings, and are a class of organic pollutants with strong "tri-toxic" effects. There are differences in the components of different exogenous remediation materials, and their effects on soil adsorption of PAHs are also inconsistent.

[0128] Verification Example 2 Testing the removal ability of the organic contaminated soil remediation material of the present invention on polycyclic aromatic hydrocarbons

[0129] Saline-alkali land contaminated by PAHs was selected. Before the experiment, the contents of phenanthrene and pyrene in the soil were measured to be 67.56 mg / kg and 82.14 mg / kg, respectively.

[0130] Seven plots of land were selected, and 200 kg of organic contaminated soil remediation materials prepared in Example 1, Example 2, and Comparative Examples 1-4 and 1500 kg of farmyard manure per mu were added respectively. The control group added 1500 kg of farmyard manure per mu and planted cabbage for comparative experiments. The cabbage grown for 70 days was harvested and landfilled, and the content of phenanthrene and pyrene in the soil after harvest was detected. Figure 2 , Figure 3 As shown, the residual phenanthrene and pyrene contents in the soil of the plot where only farmyard manure was added to plant cabbage were 28.65 mg / kg and 31.54 mg / kg, respectively; the residual phenanthrene and pyrene contents in the soil of the plot where farmyard manure and the organic contaminated soil remediation material prepared in Example 1 were added to plant cabbage were 3.21 mg / kg and 5.35 mg / kg, respectively.

[0131] Comparative Example 1 did not add bamboo charcoal, and the remediation effect on organic contaminated soil was worse than that of Example 1. Comparative Example 2 did not modify the soybean straw biochar, and the remediation effect on organic contaminated soil was worse than that of Example 1. In the soybean straw biochar modification treatment of Comparative Example 3, potassium permanganate solution was not used for soaking, and the remediation effect on organic contaminated soil was worse than that of Example 1. Comparative Example 4 replaced soybean straw biochar with peanut shell biochar, changed the composition and proportion of the enzyme solution, and the remediation effect on organic contaminated soil was worse than that of Example 1.

[0132] The graphene oxide modified biochar prepared by the present invention increases the number of oxygen-containing functional groups on the surface of soybean straw biochar, increases adsorption active sites, has a large specific surface area, good air permeability and water permeability, has the advantages of large adsorption capacity, high adsorption efficiency, etc., and has a good adsorption and removal effect on organic pollution in the soil. Adding two biochars has a better removal effect on polycyclic aromatic hydrocarbons than adding only one biochar. After the bamboo charcoal and graphene oxide modified biochar of the present invention are mixed with enzyme solution, they are grafted and cross-linked together through free radical reaction under the action of a cross-linking agent to form a three-dimensional network polymer, and the enzyme solution is loaded on the polymer, which not only improves the specific surface area of ​​the biochar, the number of active functional groups and the adsorption and retention capacity of pollutants, but also increases the attachment area of ​​the enzyme to be fixed, enhances the activity of the enzyme, and enhances the degradation or conversion of organic pollution by the repair material.

[0133] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, 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 material for remediating soil contaminated by persistent saline-alkali organic pollutants, characterized in that: The repair material is prepared by the following method: S1 Bamboo Charcoal Preparation The bamboo was cleaned, air-dried, and mechanically crushed with a crusher. The bamboo was pyrolyzed at 1000°C in a muffle furnace under a nitrogen atmosphere. The bamboo was taken out after cooling to room temperature, ground and sieved to obtain bamboo charcoal. Preparation of S2 modified biochar Cut soybean straw into small pieces, wash them and put them into an oven, dry them at 70°C for 12 hours, and then crush them through a 10-mesh sieve to obtain soybean straw powder; mix the soybean straw powder with graphene oxide, pyrolyze them at 700-750°C for 1-2 hours under nitrogen protection to obtain mixed biochar; soak the mixed biochar in potassium permanganate solution, pyrolyze them at 700-750°C for 1-2 hours to obtain graphene oxide modified biochar; S3 modified biochar adsorption enzyme solution The bamboo charcoal, graphene oxide modified biochar and enzyme solution were uniformly mixed in a mass ratio of 2:2:5 and subjected to constant temperature adsorption to obtain a modified biochar composite enzyme solution; The enzyme solution contains cellulase, xylanase, urease, amylase and protease, and the mass ratio of the cellulase, xylanase, urease, amylase and protease is (1-3): (2-4): (1-3): (3-5): 1; S4 crosslink Mix NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution to obtain a mixed solvent, stir and cross-link in an ice water bath, then move to room temperature for drying, rinse with clean water, and dry to obtain an organic contaminated soil remediation material; the mass ratio of NN-methylenebisacrylamide, sodium alginate, purified water and composite enzyme solution is 2:3:10:20, the concentration of NN-methylenebisacrylamide is 0.45 mol / L, and the concentration of sodium alginate is 0.85 mol / L; In the step S2, the mass ratio of the soybean straw powder to graphene oxide is 250-270:1; the mass ratio of the mixed biochar to the potassium permanganate solution is 1-2:20, and the mass concentration of the potassium permanganate solution is 5%.

2. The repair material according to claim 1, characterized in that The step S1 is to wash the bamboo, air dry it naturally for 2 days, crush it mechanically with a crusher for 20 minutes, heat it to 1000°C at a heating rate of 10°C / min in a muffle furnace under a nitrogen atmosphere, and keep it for pyrolysis for 2 hours, cool it to room temperature, take it out, grind it through a 100-mesh sieve, and obtain bamboo charcoal.

3. The repair material according to claim 1, characterized in that In the step S2, the mass ratio of the soybean straw powder to graphene oxide is 260:1; the mass ratio of the mixed biochar to the potassium permanganate solution is 1.5:20, and the mass concentration of the potassium permanganate solution is 5%.

4. The repair material according to claim 1, characterized in that In the step S3, the adsorption temperature is 15-20° C. and the adsorption time is 3-3.5 hours.

5. The repair material according to claim 1, characterized in that In step S3, the mass ratio of cellulase, xylanase, urease, amylase and protease is 2:3:2:4:

1.

6. The repair material according to claim 1, characterized in that In step S4, the cross-linking is stirred in an ice water bath for 10-15 minutes, dried at room temperature for 10-15 minutes, and rinsed with clean water 2-4 times.

7. The repair material according to claim 6, characterized in that In step S4, the cross-linking was stirred in an ice water bath for 12 minutes, dried at room temperature for 12 minutes, and rinsed with clean water for 3 times.

8. Use of the saline-alkali land organic contaminated soil remediation material according to claim 1 in in-situ remediation of soil organic contamination.

9. The use according to claim 8, characterized in that: The organic pollution is nitrochlorobenzene, trichloroethylene and / or polycyclic aromatic hydrocarbons pollution.

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