A soil conditioner and its preparation method and application

Abstract

The present invention provides a soil conditioner and a preparation method and application thereof, belonging to the technical field of soil conditioners. The soil conditioner of the present invention comprises the following raw materials in parts by weight: 70 to 90 parts of modified pig manure biochar, 8 to 15 parts of polyaspartic acid, 5 to 10 parts of potassium titanium oxalate, 1 to 3 parts of ammonium molybdate, 40 to 60 parts of calcium silicate, and 20 to 30 parts of lime. The present invention uses a mixed modifier to modify pig manure biochar, which can greatly reduce the content of cadmium and arsenic in edible parts. In addition, the raw materials in the soil conditioner cooperate with each other to reduce the content of heavy metals in the edible parts to the greatest extent.

Description

Technical Field

[0001] The present invention relates to the technical field of soil conditioners, and in particular to a soil conditioner and a preparation method and application thereof. Background Art

[0002] At present, soil heavy metal pollution is becoming more and more serious, especially in farmland soil. Heavy metal pollution has caused the heavy metal content in agricultural products to seriously exceed the standard, posing a threat to people's health. Most of the soil conditioners currently used are for soils contaminated with a single type of heavy metal. For farmland contaminated with cadmium and arsenic, due to the differences in the properties of cadmium and arsenic and the differences in their forms in the soil, the methods for treating cadmium-contaminated soil are not suitable for treating arsenic-contaminated soil. The difficulty of repairing cadmium-arsenic compound contaminated soil is much higher than that of repairing single cadmium-contaminated soil.

[0003] There are few reports on soil conditioners for farmland contaminated by cadmium and arsenic. Therefore, it is of great significance to study a soil conditioner and a preparation method thereof and use it for the conditioning of soil contaminated by cadmium and arsenic. Summary of the invention

[0004] The object of the present invention is to provide a soil conditioner and a preparation method and application thereof, so as to solve the problem that the soil conditioner in the prior art cannot simultaneously reduce the contents of cadmium and arsenic in edible parts.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a soil conditioner, which comprises the following raw materials in parts by weight: 70-90 parts of modified pig manure sludge biochar, 8-15 parts of polyaspartic acid, 5-10 parts of potassium titanium oxalate, 1-3 parts of ammonium molybdate, 40-60 parts of calcium silicate, and 20-30 parts of lime.

[0007] Preferably, the method for preparing modified pig manure digestate biochar comprises the following steps:

[0008] (1) drying, crushing, and calcining pig manure biogas residue to obtain pig manure biogas residue biochar;

[0009] (2) soaking the pig manure biochar in a mixed modifier, and then filtering, washing, and drying to obtain modified pig manure biochar;

[0010] The mixed modifier in step (2) is prepared by mixing citric acid, octadecyltrimethylammonium chloride and water.

[0011] Preferably, in step (1), the calcination temperature is 500-700° C., and the calcination time is 1-3 hours.

[0012] Preferably, in step (2), the mass volume ratio of the pig manure sludge biochar and the mixed modifier is 1 g: 3-8 mL.

[0013] Preferably, in the mixed modifier, the concentration of citric acid is 0.2-0.4 mol / L, and the concentration of octadecyltrimethylammonium chloride is 10-20 g / L.

[0014] Preferably, in step (2), the immersion temperature is 40 to 60° C., and the immersion time is 8 to 10 hours.

[0015] The invention provides a method for preparing a soil conditioner, which comprises mixing various raw materials according to a weight ratio and granulating the obtained mixture.

[0016] The invention provides an application of a soil conditioner in soil improvement, which comprises mixing the soil conditioner and soil.

[0017] Preferably, the application amount of the soil conditioner is 55-75 kg / mu.

[0018] Beneficial effects of the present invention:

[0019] (1) The present invention utilizes pig manure sludge to prepare modified pig manure sludge biochar, fully utilizing biosludge waste and realizing waste utilization.

[0020] (2) The present invention uses a mixed modifier to modify pig manure sludge, which can greatly reduce the content of cadmium and arsenic in the edible part compared with a single modifier.

[0021] (3) The various raw materials in the soil conditioner of the present invention cooperate with each other to passivate and chelate the heavy metals cadmium and arsenic in the soil, and can reduce the content of heavy metals in edible parts to the greatest extent. DETAILED DESCRIPTION

[0022] The present invention provides a soil conditioner, which comprises the following raw materials in parts by weight: 70-90 parts of modified pig manure sludge biochar, 8-15 parts of polyaspartic acid, 5-10 parts of potassium titanium oxalate, 1-3 parts of ammonium molybdate, 40-60 parts of calcium silicate, and 20-30 parts of lime.

[0023] In the present invention, the weight proportion of the modified pig manure sludge biochar is preferably 72 to 88 parts, and more preferably 75 to 85 parts.

[0024] In the present invention, the weight portion of the polyaspartic acid is preferably 10 to 14 parts, and more preferably 11 to 13 parts.

[0025] In the present invention, the weight portion of the potassium titanium oxalate is preferably 6 to 9 parts, and more preferably 7 to 8 parts.

[0026] In the present invention, the weight portion of the ammonium molybdate is preferably 2 parts.

[0027] In the present invention, the weight portion of the calcium silicate is preferably 42 to 58 parts, and more preferably 45 to 55 parts.

[0028] In the present invention, the weight portion of the lime is preferably 22 to 28 parts, more preferably 25 parts.

[0029] In the present invention, the method for preparing modified pig manure digestate biochar comprises the following steps:

[0030] (1) drying, crushing, and calcining pig manure biogas residue to obtain pig manure biogas residue biochar;

[0031] (2) soaking the pig manure biochar in a mixed modifier, and then filtering, washing, and drying to obtain modified pig manure biochar;

[0032] The mixed modifier in step (2) is prepared by mixing citric acid, octadecyltrimethylammonium chloride and water.

[0033] In the present invention, in the step (1), calcination is preferably carried out in a nitrogen atmosphere, the calcination temperature is 500-700°C, preferably 520-680°C, more preferably 550-650°C; the calcination time is 1-3h, preferably 1.5-2.5h, more preferably 2h.

[0034] In the present invention, in the step (2), the mass volume ratio of the pig manure sludge biochar and the mixed modifier is 1g:3-8mL, preferably 1g:4-7mL, and more preferably 1g:5-6mL.

[0035] In the present invention, in the mixed modifier, the concentration of citric acid is 0.2-0.4 mol / L, preferably 0.25-0.35 mol / L, and more preferably 0.3 mol / L; the concentration of octadecyltrimethylammonium chloride is 10-20 g / L, preferably 12-18 g / L, and more preferably 14-16 g / L.

[0036] In the present invention, in the step (2), the immersion temperature is 40 to 60°C, preferably 45 to 55°C, and more preferably 50°C; the immersion time is 8 to 10 hours, preferably 8.5 to 9.5 hours, and more preferably 9 hours.

[0037] The invention provides a method for preparing a soil conditioner, which comprises mixing various raw materials according to a weight ratio and granulating the obtained mixture.

[0038] The invention provides an application of a soil conditioner in soil improvement, which comprises mixing the soil conditioner and soil.

[0039] In the present invention, the application amount of the soil conditioner is 55-75 kg / mu, preferably 60-70 kg / mu, and more preferably 65 kg / mu.

[0040] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0041] Example 1

[0042] The solid pig manure digestate from anaerobic fermentation for 35 days was dried in an oven at 80°C for 20h, and then the dried pig manure digestate was crushed and passed through an 80-mesh sieve; the sieved powder was placed in a tube furnace, nitrogen was introduced, the temperature of the tube furnace was raised to 600°C, and calcined for 2h to obtain pig manure digestate biochar. 10g of pig manure digestate biochar was immersed in 50mL of a mixed modifier (the mixed modifier was made of citric acid, octadecyltrimethylammonium chloride and deionized water, wherein the concentration of citric acid was 0.3mol / L and the concentration of octadecyltrimethylammonium chloride was 15g / L), immersed at a temperature of 50°C for 8h, then filtered and washed with deionized water 3 times, and finally placed in an oven at 60°C for 24h to obtain modified pig manure digestate biochar.

[0043] Prepare the raw materials according to the following weight parts: 80 parts of modified pig manure biochar, 10 parts of polyaspartic acid, 8 parts of potassium titanium oxalate, 2 parts of ammonium molybdate, 50 parts of calcium silicate, and 25 parts of lime. Mix the above raw materials evenly, grind them, pass through an 80-mesh sieve, and finally extrusion granulate to obtain a soil conditioner.

[0044] Example 2

[0045] The solid pig manure digestate from anaerobic fermentation for 35 days was dried in an oven at 80°C for 20h, and then the dried pig manure digestate was crushed and passed through an 80-mesh sieve; the sieved powder was placed in a tube furnace, nitrogen was introduced, the temperature of the tube furnace was raised to 500°C, and calcined for 3h to obtain pig manure digestate biochar. 10g of pig manure digestate biochar was immersed in 80mL of a mixed modifier (the mixed modifier was made of citric acid, octadecyltrimethylammonium chloride and deionized water, wherein the concentration of citric acid was 0.4mol / L and the concentration of octadecyltrimethylammonium chloride was 20g / L), immersed at a temperature of 50°C for 8h, then filtered and washed with deionized water 3 times, and finally placed in an oven at 60°C for 24h to obtain modified pig manure digestate biochar.

[0046] Prepare the raw materials according to the following weight parts: 80 parts of modified pig manure biochar, 10 parts of polyaspartic acid, 8 parts of potassium titanium oxalate, 2 parts of ammonium molybdate, 50 parts of calcium silicate, and 25 parts of lime. Mix the above raw materials evenly, grind them, pass through an 80-mesh sieve, and finally extrusion granulate to obtain a soil conditioner.

[0047] Example 3

[0048] The solid pig manure digestate from anaerobic fermentation for 35 days was dried in an oven at 80°C for 20h, and then the dried pig manure digestate was crushed and passed through an 80-mesh sieve; the sieved powder was placed in a tube furnace, nitrogen was introduced, the temperature of the tube furnace was raised to 700°C, and calcined for 1h to obtain pig manure digestate biochar. 10g of pig manure digestate biochar was soaked in 30mL of a mixed modifier (the mixed modifier was made of citric acid, octadecyltrimethylammonium chloride and deionized water, wherein the concentration of citric acid was 0.2mol / L and the concentration of octadecyltrimethylammonium chloride was 10g / L), soaked at a temperature of 50°C for 8h, then filtered and washed with deionized water 3 times, and finally placed in an oven at 60°C for 24h to obtain modified pig manure digestate biochar.

[0049] Prepare the raw materials according to the following weight parts: 80 parts of modified pig manure biochar, 10 parts of polyaspartic acid, 8 parts of potassium titanium oxalate, 2 parts of ammonium molybdate, 50 parts of calcium silicate, and 25 parts of lime. Mix the above raw materials evenly, grind them, pass through an 80-mesh sieve, and finally extrusion granulate to obtain a soil conditioner.

[0050] Example 4

[0051] The solid pig manure digestate from anaerobic fermentation for 35 days was dried in an oven at 80°C for 20h, and then the dried pig manure digestate was crushed and passed through an 80-mesh sieve; the sieved powder was placed in a tube furnace, nitrogen was introduced, the temperature of the tube furnace was raised to 600°C, and calcined for 2h to obtain pig manure digestate biochar. 10g of pig manure digestate biochar was soaked in 50mL of a mixed modifier (the mixed modifier was made of citric acid, octadecyltrimethylammonium chloride and deionized water, wherein the concentration of citric acid was 0.3mol / L and the concentration of octadecyltrimethylammonium chloride was 15g / L), soaked at 50°C for 8h, then filtered and washed with deionized water 3 times, and finally placed in an oven at 60°C for 24h to obtain modified pig manure digestate biochar.

[0052] Prepare the raw materials according to the following weight parts: 90 parts of modified pig manure biochar, 8 parts of polyaspartic acid, 10 parts of potassium titanium oxalate, 1 part of ammonium molybdate, 40 parts of calcium silicate, and 30 parts of lime. Mix the above raw materials evenly, grind them, pass through an 80-mesh sieve, and finally extrusion granulate to obtain a soil conditioner.

[0053] Example 5

[0054] The solid pig manure digestate from anaerobic fermentation for 35 days was dried in an oven at 80°C for 20h, and then the dried pig manure digestate was crushed and passed through an 80-mesh sieve; the sieved powder was placed in a tube furnace, nitrogen was introduced, the temperature of the tube furnace was raised to 600°C, and calcined for 2h to obtain pig manure digestate biochar. 10g of pig manure digestate biochar was soaked in 50mL of a mixed modifier (the mixed modifier was made of citric acid, octadecyltrimethylammonium chloride and deionized water, wherein the concentration of citric acid was 0.3mol / L and the concentration of octadecyltrimethylammonium chloride was 15g / L), soaked at 50°C for 8h, then filtered and washed with deionized water 3 times, and finally placed in an oven at 60°C for 24h to obtain modified pig manure digestate biochar.

[0055] Prepare the raw materials according to the following weight parts: 70 parts of modified pig manure biochar, 15 parts of polyaspartic acid, 5 parts of potassium titanium oxalate, 3 parts of ammonium molybdate, 60 parts of calcium silicate, and 20 parts of lime. Mix the above raw materials evenly, grind them, pass through an 80-mesh sieve, and finally extrusion granulate to obtain a soil conditioner.

[0056] Comparative Example 1

[0057] The difference from Example 1 is that the mixed modifier is replaced by octadecyltrimethylammonium chloride modifier, the concentration of octadecyltrimethylammonium chloride in the modifier is 15 g / L, and other conditions are the same.

[0058] Comparative Example 2

[0059] The difference from Example 1 is that the mixed modifier is replaced by a citric acid modifier, the concentration of citric acid in the modifier is 0.3 mol / L, and other conditions are the same.

[0060] Comparative Example 3

[0061] The difference from Example 1 is that potassium titanium oxalate is not added, and other conditions are the same.

[0062] Comparative Example 4

[0063] The difference from Example 1 is that polyaspartic acid is not added, and other conditions are the same.

[0064] Comparative Example 5

[0065] The difference from Example 1 is that the calcination temperature is 800° C., and other conditions are the same.

[0066] Comparative Example 6

[0067] The difference from Example 1 is that the calcination temperature is 400° C., and other conditions are the same.

[0068] A contaminated test field was selected, in which the concentration of Cd was 1.8 mg / kg and the concentration of As was 30.25 mg / kg. The test field was then divided into 12 test areas of equal area, one of which was used as a control group (without any conditioner), and the other 11 test areas were used as test groups. The soil conditioners prepared in Examples 1 to 5 and Comparative Examples 1 to 6 were applied in each test area (with an application amount of 65 kg / mu). When applying, the soil conditioners were applied into the soil tillage layer of 0 to 20 cm, and then the test field was irrigated so that the water surface was 1.5 cm higher than the soil surface, and finally Chinese cabbage was planted.

[0069] The contents of Cd and As in the edible parts of Chinese cabbage produced in different test areas were tested, and the changes in the contents of Cd and As in the edible parts of the test group and the control group were compared. The results are shown in Table 1:

[0070] Table 1 Results of determination of reduction rates of Cd and As in edible parts of Chinese cabbage

[0071]

[0072]

[0073] It can be seen from Table 1 that the soil conditioner of the present invention can reduce the Cd content in the edible part while also reducing the As content in the edible part. The soil conditioner prepared by the present invention reduces the Cd content in the edible part by 70.89-75.38%, and reduces the As content in the edible part by 60.52-65.27%. It can be seen that the soil conditioner of the present invention has a passivation and chelation effect on the heavy metals cadmium and arsenic in the soil, and can reduce the content of heavy metals in the edible part to the greatest extent.

[0074] It can be seen from the above embodiments that the present invention provides a soil conditioner and its preparation method and application. The soil conditioner of the present invention comprises the following raw materials in parts by weight: 70-90 parts of modified pig manure biochar, 8-15 parts of polyaspartic acid, 5-10 parts of potassium titanium oxalate, 1-3 parts of ammonium molybdate, 40-60 parts of calcium silicate, and 20-30 parts of lime. The present invention uses a mixed modifier to modify pig manure biochar, which can greatly reduce the content of cadmium and arsenic in the edible parts. In addition, the raw materials in the soil conditioner cooperate with each other to minimize the content of heavy metals in the edible parts.

[0075] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A soil conditioner, characterized in that: The soil conditioner comprises the following raw materials in parts by weight: 70-90 parts of modified pig manure biochar, 8-15 parts of polyaspartic acid, 5-10 parts of potassium titanium oxalate, 1-3 parts of ammonium molybdate, 40-60 parts of calcium silicate, and 20-30 parts of lime; The method for preparing modified pig manure digestate biochar comprises the following steps: (1) drying, crushing, and calcining pig manure biogas residue to obtain pig manure biogas residue biochar; (2) soaking the pig manure biochar in a mixed modifier, and then filtering, washing, and drying to obtain modified pig manure biochar; In the step (1), the calcination temperature is 500 to 700° C. and the calcination time is 1 to 3 hours; The mixed modifier in step (2) is prepared by mixing citric acid, octadecyltrimethylammonium chloride and water.

2. The soil conditioner according to claim 1, characterized in that In the step (2), the mass volume ratio of the pig manure residue biochar and the mixed modifier is 1 g: 3 to 8 mL.

3. The soil conditioner according to claim 2, characterized in that In the mixed modifier, the concentration of citric acid is 0.2-0.4 mol / L, and the concentration of octadecyltrimethylammonium chloride is 10-20 g / L.

4. The soil conditioner according to claim 1 or 3, characterized in that In the step (2), the immersion temperature is 40 to 60° C., and the immersion time is 8 to 10 hours.

5. The method for preparing the soil conditioner according to any one of claims 1 to 4, characterized in that: The raw materials are mixed according to a weight ratio, and the obtained mixture is granulated.

6. Use of the soil conditioner according to any one of claims 1 to 4 in soil improvement, characterized in that: Just mix the soil conditioner and soil.

7. The use according to claim 6, characterized in that: The application amount of the soil conditioner is 55-75 kg / mu.

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