Preparation method and application of sludge biochar humic acid soil remediation agent

Abstract

The invention relates to the technical field of soil remediation, and particularly discloses a preparation method and application of a sludge biochar humic acid soil remediation agent. The preparation method of the sludge biochar humic acid soil remediation agent comprises the following steps: dewatering and drying sludge, grinding the sludge into powder, putting the powder into a tubular furnace, heating the tubular furnace to 600 DEG C under an anaerobic condition, pyrolyzing for 2 hours, and cooling to room temperature to obtain a first product; carrying out acid pickling on the first product, and cleaning until the pH is 7 to obtain a second product; drying and grinding the second product, sieving with a 100-mesh sieve to obtain sludge biochar (SBC), uniformly mixing sodium humate powder with wood vinegar to obtain a first mixed solution, adding the sludge biochar into the first mixed solution, and uniformly mixing to obtain a second mixed solution; standing the second mixed solution, filtering to obtain a third product, drying the third product, and grinding into powder to obtain the soil remediation agent, so that the soil remediation capability of the soil remediation agent is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of soil remediation, and in particular to a preparation method and application of a sludge biochar humic acid soil remediation agent. Background Art

[0002] With the rapid development of urbanization and industrialization, heavy metal pollution in farmland has affected the normal growth of crops and caused great harm to human health, seriously affecting ecological security and the stable development of green agriculture. Among them, lead-contaminated soil is more serious. Lead-containing soil not only affects soil microorganisms, enzyme activity and physical and chemical properties, but also causes secondary pollution of surface water and groundwater, and endangers human health through the food chain.

[0003] At present, the main methods for controlling heavy metal pollution in soil include immobilization / stabilization, leaching, soil washing, electrodynamic remediation, chemical reduction, phytoremediation, and microbial remediation, but they basically have problems such as low remediation efficiency and high treatment cost. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the present invention provides, on the one hand, a method for preparing a sludge biochar humic acid soil remediation agent to improve the soil remediation ability of the soil remediation agent.

[0005] A method for preparing a sludge biochar humic acid soil remediation agent comprises the following steps:

[0006] S1, the sludge is dehydrated and dried at 105°C for 24 hours, then ground into powder and placed in a tube furnace, the tube furnace is heated to 600°C under anaerobic conditions, pyrolyzed for 2 hours, and then cooled to room temperature to obtain the first product;

[0007] S2, placing the first product in a 0.5 mol / L hydrochloric acid solution for pickling, and washing the pickled product with deionized water until the pH is 7 to obtain a second product;

[0008] S3, drying the second product at 105° C. for 24 h, grinding it and passing it through a 100-mesh sieve to obtain sludge biochar (SBC);

[0009] S4, mixing the sodium humate powder and the wood vinegar to obtain a first mixed solution, adding the sludge biochar to the first mixed solution and mixing them to obtain a second mixed solution;

[0010] S5. The second mixed solution is allowed to stand at 25° C. for 14 days, and then filtered to obtain a third product. The third product is baked in an oven at 105° C. for 12 hours, and then ground into powder and passed through a 100-mesh sieve to obtain a soil remediation agent.

[0011] Optionally, the mass ratio of the sludge biochar, sodium humate and wood vinegar is 1:1:3.

[0012] Optionally, in step S1, the temperature in the tube furnace is increased to 600°C at 15°C / min.

[0013] Heating at a rate of 15 °C / min helps to increase the fixed carbon content and carbon content of biochar while maintaining the basic structure of functional groups and improving the soil remediation ability of soil remediation agents.

[0014] Optionally, the sodium humate powder is obtained by grinding sodium humate through a 100-mesh sieve. The sodium humate is a dark brown powder ground from weathered coal or lignite, and the free value is greater than 52%. The pH value of the sodium humate is 10.5, the density is 0.73 kg / L, and the water solubility is greater than 85%.

[0015] Optionally, the wood vinegar is composed of the following raw materials in the following mass ratios:

[0016] Acetic acid 78.20%;

[0017] Phenol 7.86%;

[0018] Ketones and alcohols 12.66%;

[0019] Other 1.28%.

[0020] Optionally, in step S4, the wood vinegar is allowed to stand at 25° C. for 10 days and then filtered and distilled, and the fraction at 120-150° C. is collected. The pH value of the wood vinegar is 3.96.

[0021] Optionally, in step S5, the third product is air-dried at 25° C. for 24 hours before baking the third product.

[0022] Another aspect of the present invention provides the use of the above-mentioned sludge biochar humic acid soil remediation agent, wherein the usage amount of the soil remediation agent is 1-5g of the soil remediation agent per 1kg of soil.

[0023] The beneficial effects of the present invention are as follows: the soil remediation agent prepared by using biochar prepared from sludge of sewage treatment plants, wood vinegar produced as a byproduct in the process of charcoal production, and sodium humic acid salt extracted from lignite as raw materials can be used for the remediation of farmland soil contaminated with heavy metals. The invention has low price, wide sources, and is easy to promote and use, and can achieve the effect of treating waste with waste and turning waste into treasure; humic acid is prepared by acidifying sodium humate with wood vinegar, and then loaded onto sludge biochar to form a composite material. The application of this material not only does not cause secondary pollution to the soil, but also opens up a new way for resource utilization of industrial waste. The present invention improves the soil remediation ability of the soil remediation agent through the synergistic effect of sludge biochar and humic acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1( a ) is a graph showing the effect of 1 g of soil remediation agent of Example 1 of the present invention and Comparative Examples 1-5 on the effective lead in 1 kg of lead-contaminated soil sample.

[0025] FIG1( b ) is a graph showing the effect of 1 g of soil remediation agent of Example 2 of the present invention on the effective lead in 1 kg of lead-contaminated soil sample.

[0026] FIG2( a ) is a graph showing the effects of different amounts of soil remediation agents in Example 1, Comparative Example 1 and Comparative Example 3 of the present invention on the effective lead in 1 kg of lead-contaminated soil sample.

[0027] FIG2( b ) is a graph showing the effects of different amounts of soil remediation agent according to Example 1 of the present invention on the chemical components of lead in 1 kg of lead-contaminated soil sample.

[0028] Figure 3 This is a graph showing the effect of the aging time of the present invention on the adsorption of effective lead in soil by the soil remediation agent of Example 1.

[0029] Figure 4 FT-IR spectra of the soil remediation agents of Example 1 and Comparative Example 1 before and after adsorption of Pb(II) ions.

[0030] Figure 5 This is a scanning electron microscope image of the soil remediation agent of Example 1 of the present invention magnified 2000 times.

[0031] Figure 6 This is a scanning electron microscope image of the soil remediation agent of Comparative Example 1 of the present invention magnified 2000 times.

[0032] FIG. 7( a ) is a high-resolution Cls spectrum of the soil remediation agent of Comparative Example 1 of the present invention before adsorbing Pb(II) ions.

[0033] FIG7( b ) is a high-resolution Cls spectrum of the soil remediation agent of Comparative Example 1 of the present invention after adsorbing Pb(II) ions.

[0034] FIG8( a ) is a high-resolution Cls spectrum of the soil remediation agent of Example 1 of the present invention before adsorbing Pb(II) ions.

[0035] FIG8( b ) is a high-resolution Cls spectrum of the soil remediation agent of Example 1 of the present invention after adsorbing Pb(II) ions. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in 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 creative work are within the scope of protection of the present invention.

[0037] Example

[0038] Example 1

[0039] A method for preparing a sludge biochar humic acid soil remediation agent comprises the following steps:

[0040] 20g of sludge was dehydrated and dried at 105°C for 24h, then ground into powder and placed in a tube furnace, the tube furnace was heated to 600°C at a rate of 15°C / min under anaerobic conditions, pyrolyzed for 2h and then cooled to 25°C to obtain a first product; the first product was placed in a 0.5mol / L hydrochloric acid solution for pickling, and the pickled product was washed with deionized water to pH=7 to obtain a second product; the second product was dried at 105°C for 24h, ground and sieved through a 100-mesh sieve to obtain sludge biochar (SBC), the C, H, O, N elements and ash contents of the sludge biochar were 34.01%, 1.62%, 23.38%, 4.69% and 36.03% respectively; the sodium humate powder was obtained by grinding sodium humate through a 100-mesh sieve, the sodium humate was a dark brown powder ground from weathered coal or lignite, the free value was greater than 52%, the humic acid powder was 1.62%, 23.38%, 4.69% and 36.03% respectively. The pH value of sodium humate is 10.5, the density is 0.73 kg / L, and the water solubility is greater than 85%. Through GC-MS analysis, the wood vinegar is composed of the following raw materials in the following mass ratios: acetic acid 78.20%, phenol 7.86%, ketones, alcohols 12.66%, and others 1.28%. The wood vinegar is filtered and distilled after standing at 25°C for 10 days, and the fraction at 120-150°C is collected. The pH value of the wood vinegar is 3.96; 20g of sodium humate powder is mixed with 60g of wood vinegar to obtain a first mixed solution, and the sludge biochar is added to the first mixed solution and mixed to obtain a second mixed solution; the second mixed solution is allowed to stand at 25°C for 14 days and then filtered to obtain a third product, and the third product is air-dried at 25°C for 24 hours, added to an oven, baked at 105°C for 12 hours, ground into powder and passed through a 100-mesh sieve to obtain a soil remediation agent (SBC-HA).

[0041] Example 2

[0042] A method for preparing a sludge biochar humic acid soil remediation agent, which is different from Example 1 in that the mass ratio of the sludge biochar, sodium humate, and wood vinegar is 1:1.5:1 to obtain a soil remediation agent (BC-HA).

[0043] Comparative Example

[0044] Comparative Example 1

[0045] A preparation method of a sludge biochar humic acid soil remediation agent comprises the following steps: 50 g of sludge is dehydrated and dried at 105° C. for 24 hours, then ground into powder and placed in a tube furnace, the tube furnace is heated to 600° C. under anaerobic conditions, pyrolyzed for 2 hours, and then cooled to room temperature to obtain a first product; the first product is placed in a 0.5 mol / L hydrochloric acid solution for pickling, and the pickled product is washed with deionized water to a pH of 7 to obtain a second product; the second product is dried at 105° C. for 24 hours, ground and sieved through a 100-mesh sieve to obtain sludge biochar (SBC), wherein the C, H, O, N elements and ash contents of the sludge biochar are 34.01%, 1.62%, 23.38%, 4.69% and 36.03%, respectively; the sodium humate powder is obtained by grinding sodium humate through a 100-mesh sieve, the sodium humate is a dark brown powder ground from weathered coal or lignite, and the free value is greater than 52%, The pH value of the sodium humate is 10.5, the density is 0.73 kg / L, and the water solubility is greater than 85%. According to GC-MS analysis, the wood vinegar is composed of the following raw materials in the following mass ratios: 78.20% acetic acid, 7.86% phenol, 12.66% ketones and alcohols, and 1.28% others. The wood vinegar is filtered and distilled after standing at 25° C. for 10 days, and the fraction at 120-150° C. is collected. The pH value of the wood vinegar is 3.96. 50 g of sodium humate powder and 1 kg of deionized water are mixed evenly to obtain a first mixed solution, and the sludge biochar is added to the first mixed solution and mixed evenly to obtain a second mixed solution. The second mixed solution is allowed to stand at 25° C. for 14 days, and then filtered to obtain a third product. The third product is air-dried at 25° C. for 24 hours, added to an oven, baked at 105° C. for 12 hours, ground into powder, and passed through a 100-mesh sieve to obtain a soil remediation agent (SBC-NaHA).

[0046] Comparative Example 2

[0047] A preparation method of a sludge biochar humic acid soil remediation agent, comprising the steps of: dehydrating and drying 20g of sludge at 105°C for 24h, grinding the sludge into powder and placing the sludge in a tube furnace, heating the tube furnace to 600°C under anaerobic conditions, pyrolyzing the sludge for 2h, and cooling the sludge to room temperature to obtain a first product; placing the first product in a 0.5mol / L hydrochloric acid solution for pickling, and washing the pickled product with deionized water until the pH value is 7 to obtain a second product; drying the second product at 105°C for 24h, grinding the sludge biochar (SBC) through a 100-mesh sieve to obtain sludge biochar (SBC), wherein the C, H, O, N elements and ash contents of the sludge biochar are 34.01%, 1.62%, 23.38%, 4.69% and 36.03% respectively; the sodium humate powder is obtained by grinding the sodium humate through a 100-mesh sieve, wherein the sodium humate is a dark brown powder ground from weathered coal or lignite, and the free value is greater than 52%. The pH value of the sodium humate is 10.5, the density is 0.73kg / L, and the water solubility is greater than 85%. According to GC-MS analysis, the wood vinegar is composed of the following raw materials in the following mass ratios: 78.20% acetic acid, 7.86% phenol, 12.66% ketones and alcohols, and 1.28% others. The wood vinegar is filtered and distilled after standing at 25°C for 10 days, and the fraction at 120-150°C is collected. The pH value of the wood vinegar is 3.96; 75g of sodium humate powder and 1kg of deionized water are mixed evenly to obtain a first mixed solution, and the sludge biochar is added to the first mixed solution and mixed evenly to obtain a second mixed solution; the second mixed solution is allowed to stand at 25°C for 14 days and then filtered to obtain a third product, and the third product is air-dried at 25°C for 24h, added to an oven, baked at 105°C for 12h, ground into powder and passed through a 100-mesh sieve to obtain a soil remediation agent (SBC-WV).

[0048] Comparative Example 3

[0049] A method for preparing a sludge biochar humic acid soil remediation agent comprises the following steps: dehydrating and drying 100 g of sludge at 105° C. for 24 hours, grinding the sludge into powder and placing the powder in a tube furnace; heating the tube furnace to 600° C. under anaerobic conditions, pyrolyzing the powder for 2 hours and then cooling the powder to room temperature to obtain a first product; placing the first product in a 0.5 mol / L hydrochloric acid solution for pickling, and washing the pickled product with deionized water to a pH of 7 to obtain a second product; and drying the second product at 105° C. for 24 hours, grinding the second product and passing it through a 100-mesh sieve to obtain sludge biochar (SBC).

[0050] Comparative Example 4

[0051] A method for preparing a sludge biochar humic acid soil remediation agent comprises the following steps: through GC-MS analysis, the wood vinegar is composed of the following raw materials in the following mass ratio: 78.20% of acetic acid, 7.86% of phenol, 12.66% of ketones and alcohols, and 1.28% of others; the wood vinegar is filtered and distilled after standing at 25°C for 10 days; the fraction at 120-150°C is collected; the pH value of the wood vinegar is 3.96; 100g of the wood vinegar is filtered to obtain a soil remediation agent (WV).

[0052] Comparative Example 5

[0053] A method for preparing a sludge biochar humic acid soil remediation agent, wherein the sodium humate powder is obtained by grinding sodium humate through a 100-mesh sieve, the sodium humate is a dark brown powder ground from weathered coal or lignite, and the free value is greater than 52%, the pH value of the sodium humate is 10.5, the density is 0.73 kg / L, and the water solubility is greater than 85% according to GC-MS analysis, and the wood vinegar is composed of the following raw materials in the following mass ratios: acetic acid 78.20%, phenol 7.86%, ketones, alcohols 12.66%, The other 1.28%, the wood vinegar is filtered and distilled after standing at 25°C for 10 days, and the fraction at 120-150°C is collected, and the pH value of the wood vinegar is 3.96; 25g of sodium humate powder and 75g of wood vinegar are mixed evenly to obtain a first mixed solution, which is allowed to stand at 25°C for 14 days and then filtered to obtain a third product, and the third product is air-dried at 25°C for 24h, added to an oven, baked at 105°C for 12h, ground into powder and passed through a 100-mesh sieve to obtain a soil remediation agent (HA).

[0054] Performance Testing

[0055] The following performance tests were performed on the soil remediation agents provided in Examples 1-2 and Comparative Examples 1-5 of the present invention:

[0056] Laboratory simulated lead-contaminated soil samples: 0-20 cm surface soil was taken from agricultural land in Baoji City, Shaanxi Province. After natural air drying, rocks, debris, and animal and plant remains were removed and sieved through a 100-mesh sieve for use as original soil samples. Lead nitrate corresponding to 500 mg of lead was weighed in a 1L beaker, and 500 mL of distilled water was added to prepare a metal solution. The metal solutions were then mixed into 1 kg of the original soil sample, placed in a fume hood, and aged for 30 days to obtain lead-contaminated soil samples.

[0057] Experiment of extracting effective lead in soil with CaCl2 at one time: 1g, 2g, 3g, 4g, 5g of the soil remediation agent of Example 1 and Comparative Examples 1-5 were mixed evenly with 1kg of lead-contaminated soil, and placed in 1.5L flower pots (diameter 15cm, height 13cm), and irrigated every day to reach 60% of the field water holding rate; under greenhouse conditions of 25 / 18℃ (day / night), all flower pots were weighed once every 5 days, and the evaporated water was replenished to maintain the moisture content, the lead-contaminated soil samples were aged for 60 days, and the five-point sampling method was used to sample the money-contaminated soil samples, and the lead-contaminated soil samples were mixed with the solution at a ratio of 1:10 with 0.01mol / L CaCl2, and the content of effective lead in the soil samples before and after the soil remediation agent treatment was extracted. The adsorption amount of heavy metals is obtained by the following formula:

[0058]

[0059] In the formula, Q e is the adsorption amount of heavy metals, mg·g -1 ; C0 is the initial concentration of heavy metals, mg·L -1 ; C e is the equilibrium concentration of heavy metals, mg·L -1 ; V is the volume of the solution, mL; m is the mass of the soil sample, g.

[0060] Experiment on the effect of aging time on soil remediation agent: At a temperature of 25°C, 1 kg of lead-contaminated soil samples from the same batch and placed for different times (7d, 14d, 21d, 28d, 35d, 42d, 49d, 56d, and 63d) were taken, and 3 g / kg of soil remediation agent (SBC-HA) was added respectively, and an experiment of extracting the effective lead in the soil with CaCl2 was carried out.

[0061] Experiment on extracting different forms of soil lead by BCR sequential extraction method: 1g, 2g, 3g, 4g, and 5g of the soil remediation agent of Example 1 were mixed evenly with 1kg of lead-contaminated soil, air-dried and ground at 25°C and passed through a 100-mesh sieve, and the lead content of four chemical forms in the lead-contaminated soil sample was extracted sequentially according to the steps in Table 1. The heavy metal ion concentrations in all extracts and filtrates were determined by atomic absorption spectrometry. Three samples were set for each ratio, and the test results were averaged.

[0062] Table 1. Sequential extraction order of nickel from BCR soil samples

[0063]

[0064]

[0065] The concentration of adsorbed Pb solution is 500 mg·L -1(0.01 mol·L -1 NaNO3 as the background), the adsorbent dosage is 25g / kg. According to the comparison of Figure 1(a) and Figure 1(b), when the soil remediation agent was added at a level of 1g / kg, the soil remediation agent (SBC-HA) significantly reduced the effective Pb(Ⅱ) content extracted by CaCl2. Compared with the blank group (CK), the soil remediation agent (SBC-HA) reduced the effective Pb(Ⅱ) content by 36.38%, which was the lowest effective Pb(Ⅱ) content among the seven soil remediation agents. The results of Figure 1(a) show that the addition of wood vinegar can enhance the ability of sludge biochar-humic acid remediation materials to adsorb Pb(Ⅱ) ions. The results of Figure 1(b) show that when the ratio of biochar-humic acid-wood vinegar is 1:1.5:1, it is obtained that compared with the blank group (CK), the soil remediation agent (BC-HA) reduced the effective state of lead by 23.81%, while the soil remediation agent (SBC-HA) reduced the effective state of lead by 30.20%.

[0066] According to Figure 2(a), the soil remediation agent (SBC-HA) reduced the effective lead content in the soil the most. Compared with the blank group (CK), at the addition level of 3.0 g / kg, the soil remediation agent (SBC) reduced the effective lead content by 25.64%, the soil remediation agent (SBC-NaHA) reduced the effective lead content by 30.42%, and the soil remediation agent (SBC-HA) reduced the effective lead content by 36.94%, which indicates that the addition of humic acid enhances the ability of sludge biochar to adsorb lead ions.

[0067] The BCR sequential extraction method was used to determine the binding form and mobility of metal ions in the soil. With the different binding forms of heavy metals in the soil, the environmental toxicity and bioavailability of heavy metals are constantly changing. According to Figure 2(b), the distribution of different forms of lead in the soil before and after the treatment with the soil remediation agent (SBC-HA). Compared with the blank group (CK), after treatment with 3.0g of soil remediation agent (SBC-HA), the exchangeable and reducible components of lead in the soil decreased by 10.09% and 12.84%, respectively, while the oxidizable and residual components of lead increased by 9.48% and 14.12%, respectively. This is because the Pb (II) content of the exchangeable and reducible components combines with the soil remediation agent (SBC-HA) to form insoluble and stable complexes, which are further converted into oxidizable and residual components. They are not easily absorbed by plants, and have low environmental migration ability and potential environmental risks.

[0068] The lower the effective content of lead in the solution, the better the adsorption and solidification performance of the soil remediation agent (SBC-HA) is. Figure 3It can be seen that the aging time is proportional to the curing performance. The longer the aging time, the higher the Pb(II) adsorbed by the soil remediation agent (SBC-HA), and the lower the mobility and toxicity of lead in the soil.

[0069] according to Figure 4 It can be seen that 3107cm -1 Corresponding to the stretching vibration of hydroxyl (-OH); 1712cm -1 Corresponding to stretching vibration of carboxyl (C=O); 1576cm -1 Attributed to the stretching vibration of aromatic C=C and C=O; 1384 cm -1 Attributed to the bending vibration of CH3; 1106cm -1 and 1021cm -1 , which is related to the stretching vibration of CO in the ether structure and C-OH. Compared with the soil remediation agent (SBC-NaHA), the absorption peaks of the carboxyl group (C=O) and hydroxyl group (C-OH) on the soil remediation agent (SBC-HA) are significantly enhanced, which shows that SBC-HA has a stronger ability to bind Pb(Ⅱ) ions. After the soil remediation agent (SBC-HA) adsorbs Pb(Ⅱ) ions, the peak intensity of the carboxyl group and hydroxyl group is greatly weakened. This is because the hydroxyl group and carboxyl group on the soil remediation agent (SBC-HA) have a coordination complex reaction with the Pb(Ⅱ) ions.

[0070] according to Figure 5 and Figure 6 By comparison, the surface morphology of soil remediation agent (SBC-HA) is more complex and porous than that of soil remediation agent (SBC-NaHA), and it has more adsorption active sites.

[0071] according to Figure 7(a)-Figure 8(b)By comparison, the C1s peaks on the soil remediation agent (SBC-NaHA) material are located at 284.60eV, 286.05eV, and 288.52eV, and the C1s peaks on the soil remediation agent (SBC-HA) are located at 284.60eV, 286.18eV, and 288.57eV, corresponding to CC / C=C, C-OH, and OC=O, respectively. The contents of CC / C=C, C-OH, and OC=O in the spectrum of the soil remediation agent (SBC-NaHA) before adsorbing Pb(Ⅱ) ions are 59.20%, 28.30%, and 12.50%, respectively, and after adsorbing Pb(Ⅱ) ions, they are 66.74%, 22.50%, and 10.16%. The contents of CC / C=C, C-OH, and OC=O in the spectrum of soil remediation agent (SBC-HA) before adsorbing Pb(Ⅱ) ions were 50.33%, 38.27%, and 11.40%, respectively, and after adsorbing Pb(Ⅱ) ions, they were 63.42%, 26.38%, and 10.20%. The above results show that the oxygen content of soil remediation agent (SBC-NaHA) and soil remediation agent (SBC-HA) significantly decreased and the carbon content significantly increased after adsorbing Pb(Ⅱ) ions. Compared with soil remediation agent (SBC-NaHA), soil remediation agent (SBC-HA) has more oxygen-containing functional groups, which is attributed to the modification of WV-acidified NaHA into HA with more oxygen-containing functional groups. The addition of HA can promote more hydroxyl and carboxyl groups to form metal complexes with Pb(Ⅱ) ions, which significantly enhances the ability of soil remediation agent (SBC-HA) to adsorb Pb(Ⅱ) ions.

[0072] Finally, it should be noted that the above description is only a preferred example of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a sludge biochar humic acid soil remediation agent, characterized in that: The steps include: S1, the sludge is dehydrated and dried at 105°C for 24 hours, then ground into powder and placed in a tube furnace, the tube furnace is heated to 600°C under anaerobic conditions, pyrolyzed for 2 hours, and then cooled to room temperature to obtain the first product; S2, placing the first product in a 0.5 mol / L hydrochloric acid solution for pickling, and washing the pickled product with deionized water until the pH is 7 to obtain a second product; S3, drying the second product at 105° C. for 24 h, grinding it and passing it through a 100-mesh sieve to obtain sludge biochar (SBC); S4, mixing the sodium humate powder and the wood vinegar to obtain a first mixed solution, adding the sludge biochar to the first mixed solution and mixing them to obtain a second mixed solution; S5. The second mixed solution is allowed to stand at 25° C. for 14 days, and then filtered to obtain a third product. The third product is baked in an oven at 105° C. for 12 hours, and then ground into powder and passed through a 100-mesh sieve to obtain a soil remediation agent.

2. The method for preparing a sludge biochar humic acid soil remediation agent according to claim 1, characterized in that: The mass ratio of the sludge biochar, sodium humate and wood vinegar is 1:1:

3.

3. The method for preparing a sludge biochar humic acid soil remediation agent according to claim 1, characterized in that: In step S1, the temperature in the tube furnace is increased to 600°C at a rate of 15°C / min.

4. The method for preparing a sludge biochar humic acid soil remediation agent according to claim 1, characterized in that: The sodium humate powder is obtained by grinding sodium humate through a 100-mesh sieve. The sodium humate is a dark brown powder ground from weathered coal or lignite, and the free value is greater than 52%. The pH value of the sodium humate is 10.5, the density is 0.73 kg / L, and the water solubility is greater than 85%.

5. The method for preparing a sludge biochar humic acid soil remediation agent according to claim 1, characterized in that: The wood vinegar is composed of the following raw materials in mass ratio: Acetic acid 78.20%; Phenol 7.86%; Ketones and alcohols 12.66%; Other 1.28%.

6. The method for preparing a sludge biochar humic acid soil remediation agent according to claim 1, characterized in that: In step S4, the wood vinegar is allowed to stand at 25° C. for 10 days and then filtered and distilled, and the fraction at 120-150° C. is collected. The pH value of the wood vinegar is 3.

96.

7. The method for preparing a sludge biochar humic acid soil remediation agent according to claim 1, characterized in that: In step S5, the third product is air-dried at 25° C. for 24 hours before being baked.

8. The use of the sludge biochar humic acid soil remediation agent according to any one of claims 1 to 7, characterized in that: The usage amount of the soil remediation agent is 1-5g of soil remediation agent per 1kg of soil.

Images