A method for preparing a saline-alkali land improver

Abstract

The invention discloses a method for preparing a saline-alkali land improver, and relates to the technical field of soil improvement, comprising the following steps: 1) immersing an activated carbon ball in a saturated solution of an organic acid and stirring for 2-3 hours, and drying to obtain an acidified ball; 2) vibrating and stirring the acidified ball and coated calcium peroxide at a weight ratio of 10:0.5-0.8 to obtain a filled ball; 3) preparing polyvinyl alcohol into a 3-5wt% solution, spraying it on the surface of the filled ball, and then rolling and coating a super absorbent resin to obtain a coated ball, 4) adding 1,4-butanediol to the 3-5wt% polyvinyl alcohol solution to form a mixed solution, spraying it on the surface of the coated ball, drying at 150°C, and having a coating thickness of 100-150μm to obtain an improver. The prepared improver not only has the functions of increasing oxygen, reducing alkali and retaining water, but also has a high strength of the inner shell, and can be dispersed in the soil to improve the permeability of the soil for a long time, thereby further increasing the effect of soil improvement.

Description

Technical Field

[0001] The invention relates to the technical field of saline-alkali land improvers, and in particular to a preparation method of a saline-alkali land improver. Background Art

[0002] Soil salinization is a process of soil salinization and soil alkalization. Soil salinization refers to the process in which salts rich in groundwater, surface water and rock parent materials gradually accumulate in the surface soil through vertical or horizontal movement of soil capillaries under the action of evaporation and transpiration. Soil alkalization refers to the accumulation of water-soluble salts on the soil surface and in the soil, usually neutral or nearly neutral salts such as sodium sulfate and sodium chloride. Therefore, salinized soil mainly refers to soil containing excessive soluble salt ions. Saline-alkali soil has a high pH, ​​high salt content, poor air permeability and water permeability, and low fertilizer efficiency, which affects the growth of crops. In addition, crops can hardly survive in areas with severe saline-alkali soil.

[0003] At present, there are three methods for improving saline-alkali land: physical method, biological method and chemical method. The physical method mainly achieves the effect of salt removal through physical irrigation and leaching. This method requires convenient water supply and has a limited scope of application. The biological method mainly adopts crop rotation, improved farming, and breeding of salt-alkali tolerant plants, which has a relatively long cycle. The chemical method mainly uses some improvers, such as biochar and organic fertilizer. Biochar has many pores, which can increase the specific surface area of ​​the soil, reduce the bulk density of the soil, improve the shrinkage of the soil, and thus increase the water holding capacity of the soil. Organic fertilizers are rich in soluble K, Ca, Mg and other components as well as some acidic nutrients. After being applied to the soil, they can change the pH of acidic soil and increase soil nutrition.

[0004] Currently, the most commonly used improvement method is to improve the soil by adding improvers and planting salt-tolerant crops. However, the problem is that improving saline-alkali soil is a long process. Conventional improvers become compacted with the soil after irrigation and rain, making it difficult to maintain the improvement effect. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a method for preparing a saline-alkali land conditioner in response to the deficiencies in the prior art. The prepared conditioner not only has the functions of increasing oxygen, reducing alkali and retaining water, but also has high strength of the inner and outer shells. When dispersed in the soil, it can improve the permeability of the soil for a long time, thereby further increasing the effect of soil improvement.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a saline-alkali land improver comprises the following steps:

[0008] 1) Immerse the activated carbon balls in a saturated solution of organic acid and stir for 2-3 hours, then dry to obtain acidified balls;

[0009] 2) Vibrate and stir the acidified balls and coated calcium peroxide in a weight ratio of 10:0.5-0.8 to obtain filled balls;

[0010] 3) Prepare a 3-5wt% solution of polyvinyl alcohol, spray it on the surface of the filled ball, and then roll it to coat the super absorbent resin to obtain the coated ball. The amount of the coated super absorbent resin is 4-5% of the total amount of the filled ball;

[0011] 4) Add 1,4-butanediol to a 3-5wt% polyvinyl alcohol solution to form a mixed solution, spray it on the surface of the coated ball, and dry it at 150°C. The coating thickness is 100-150 μm to obtain a modifier. The amount of 1,4-butanediol added is 5-6% of the total amount of polyvinyl alcohol.

[0012] Furthermore, the organic acid is citric acid or malic acid.

[0013] Furthermore, the activated carbon balls are prepared by the following steps:

[0014] 1) Mix phenolic resin, surfactant and ethanol evenly, add wood powder and continue stirring to form a suspension, then drop the suspension into hot water to form spherical particles, wherein the weight ratio of the phenolic resin, surfactant, ethanol and wood powder is 1-2:0.2:10:1;

[0015] 2) heating the spherical particles at 120-150°C for 2 hours to obtain solidified balls;

[0016] 3) The solidified balls are heated to 600-650°C in a nitrogen atmosphere for pyrolysis for 1 hour, and then activated for 2 hours to obtain activated carbon balls with a particle size of 2-4 mm.

[0017] Furthermore, the wood powder is obtained by crushing wood or fruit shells.

[0018] Furthermore, the surfactant is alkylphenol polyoxyethylene ether or Tween 20.

[0019] Furthermore, the activation temperature in step 3) is 700-800°C.

[0020] The beneficial effects of the present invention are:

[0021] 1. The present application discloses a saline-alkali land improver, wherein the activated carbon ball is first loaded with organic acid, and then filled with or adhered with coated calcium peroxide inside and on the surface, and then coated with super absorbent resin, and finally formed into a film with polyvinyl alcohol. That is, the improver contains activated carbon, organic acid, calcium peroxide and super absorbent resin, which can not only improve the pH of saline-alkali land, but also play the role of water retention, oxygenation and increasing soil permeability. It has comprehensive functions and can greatly improve the soil quality of saline-alkali land. The improver can be used in combination with organic fertilizers, urea and other fertilizers, so as to further increase the saline-alkali land soil improvement effect.

[0022] 2. The activated carbon balls in the inner layer are made of wood powder and phenolic resin through carbonization and pyrolysis. After the ethanol solution of phenolic resin and wood powder are evenly mixed, they are dropped into hot water. After the ethanol evaporates, the phenolic resin is solidified at high temperature to form spherical particles, which are further solidified at high temperature; then carbonization and pyrolysis are formed to form porous spherical particles. Since the phenolic resin slowly solidifies in the wood powder particles, it is relatively uniform, has a smooth surface, and a high porosity. Moreover, the ball wall strength formed after solidification is high. Compared with activated carbon powder, the activated carbon balls prepared in this application are applied to saline-alkali soil, which can greatly increase the permeability of the soil and have excellent improvement effect.

[0023] 3. The activated carbon balls and coated calcium peroxide powder are vibrated and stirred, and the coated calcium peroxide enters the interior of the activated carbon balls and partially adheres to the surface, and then is coated with a super absorbent resin, and finally coated. The preparation process is simple, and under the action of irrigation and rainwater, the outer polyvinyl alcohol film and the super absorbent resin inside it absorb water and swell, and mix with the soil, which not only plays a role in water retention, but also can be decomposed, which is more environmentally friendly, and the coated calcium peroxide in the activated carbon balls slowly enters the soil, playing a role in oxygenation; the comprehensive performance is excellent. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with specific embodiments. Example 1

[0025] A method for preparing a saline-alkali land improver comprises the following steps:

[0026] 1) Immerse the activated carbon balls in a saturated solution of organic acid with a weight of 5 times the weight, stir for 2 hours, and dry to obtain acidified balls;

[0027] 2) Vibrate and stir the acidified balls and coated calcium peroxide powder in a weight ratio of 10:0.5. The coated calcium peroxide powder enters the interior of the acidified balls and a small amount adheres to the surface to obtain filled balls;

[0028] 3) Prepare a 3wt% solution of polyvinyl alcohol, spray it on the surface of the filled ball, and then roll and coat the super absorbent resin to obtain a coated ball. The amount of the coated super absorbent resin is 4% of the total amount of the filled ball;

[0029] 4) 1,4-butanediol was added to a 3wt% polyvinyl alcohol solution to form a mixed solution, which was sprayed on the surface of the coated ball and dried at 150°C. The coating thickness was 130 μm to obtain a modifier. The amount of 1,4-butanediol added was 5% of the total amount of polyvinyl alcohol.

[0030] The organic acid is citric acid; the coated calcium peroxide is commercially available PVP-coated CaO2 powder, and the PVP coating amount is 0.2%.

[0031] Activated carbon balls are prepared by the following steps:

[0032] 1) Phenolic resin, surfactant and ethanol are mixed evenly, wood powder is added and stirred continuously to form a suspension, and then the suspension is dripped dropwise into 100° C. hot water to form spherical particles, wherein the weight ratio of the phenolic resin, surfactant, ethanol and wood powder is 1:0.2:10:1;

[0033] 2) heating the spherical particles at 120°C for 2 hours to obtain solidified balls;

[0034] 3) The solidified balls were heated to 600°C in a nitrogen atmosphere for pyrolysis for 1 hour, and then CO2 was introduced and the temperature was raised to 700°C for activation for 2 hours to obtain activated carbon balls with a particle size of 3 mm.

[0035] The wood powder is made from ultra-fine grinding of fruit shells; the surfactant is alkylphenol polyoxyethylene ether. Example 2

[0036] A method for preparing a saline-alkali land improver comprises the following steps:

[0037] 1) Immerse the activated carbon balls in a saturated solution of organic acid and stir for 3 hours, then dry to obtain acidified balls;

[0038] 2) Vibrate and stir the acidified balls and coated calcium peroxide in a weight ratio of 10:0.6 to obtain filled balls;

[0039] 3) Prepare a 4wt% solution of polyvinyl alcohol, spray it on the surface of the filled ball, and then roll and coat the super absorbent resin to obtain a coated ball. The amount of the coated super absorbent resin is 4.5% of the total amount of the filled ball;

[0040] 4) 1,4-butanediol was added to a 4 wt % polyvinyl alcohol solution to form a mixed solution, which was sprayed on the surface of the coated ball and dried at 150° C. The coating thickness was 150 μm to obtain a modifier, wherein the amount of 1,4-butanediol added was 5.5% of the total amount of polyvinyl alcohol.

[0041] The organic acid is malic acid; the coated calcium peroxide is commercially available PVP-coated CaO2 powder, and the PVP coating amount is 0.2%.

[0042] Activated carbon balls are prepared by the following steps:

[0043] 1) Phenolic resin, surfactant and ethanol are mixed evenly, wood powder is added and stirred continuously to form a suspension, and then the suspension is dripped drop by drop into 100° C. hot water to form spherical particles, wherein the weight ratio of the phenolic resin, surfactant, ethanol and wood powder is 1.5:0.2:10:1;

[0044] 2) After filtering the spherical particles, heat them at 130°C for 2 hours to obtain solidified balls;

[0045] 3) The solidified balls were heated to 600°C in a nitrogen atmosphere for pyrolysis for 1 h, and then CO2 was introduced and heated to 750°C for activation for 2 h to obtain activated carbon balls with a particle size of 3 mm.

[0046] The wood powder is made by crushing wood; the surfactant is Tween 20. Example 3

[0047] A method for preparing a saline-alkali land improver comprises the following steps:

[0048] 1) Immerse the activated carbon balls in a saturated solution of organic acid and stir for 2 hours, then dry to obtain acidified balls;

[0049] 2) Vibrate and stir the acidified balls and coated calcium peroxide in a weight ratio of 10:0.7 to obtain filled balls;

[0050] 3) Prepare a 4wt% solution of polyvinyl alcohol, spray it on the surface of the filled ball, and then roll and coat the super absorbent resin to obtain a coated ball. The amount of the coated super absorbent resin is 5% of the total amount of the filled ball;

[0051] 4) 1,4-butanediol was added to a 4wt% polyvinyl alcohol solution to form a mixed solution, which was sprayed on the surface of the coated ball and dried at 150°C. The coating thickness was 130 μm to obtain a modifier. The amount of 1,4-butanediol added was 6% of the total amount of polyvinyl alcohol.

[0052] The organic acid is humic acid; the coated calcium peroxide is commercially available PVP-coated CaO2 powder, and the PVP coating amount is 0.2%.

[0053] Activated carbon balls are prepared by the following steps:

[0054] 1) Phenolic resin, surfactant and ethanol are mixed evenly, wood powder is added and stirred continuously to form a suspension, and then the suspension is dripped dropwise into 100° C. hot water to form spherical particles, wherein the weight ratio of the phenolic resin, surfactant, ethanol and wood powder is 2:0.2:10:1;

[0055] 2) After filtering the spherical particles, heat them at 140°C for 2 hours to obtain solidified balls;

[0056] 3) The solidified balls were heated to 650°C in a nitrogen atmosphere for pyrolysis for 1 hour, and then CO2 was introduced and the temperature was raised to 800°C for activation for 2 hours to obtain activated carbon balls with a particle size of 3 mm.

[0057] The wood powder is made by crushing wood; and the surfactant is alkylphenol polyoxyethylene ether. Example 4

[0058] A method for preparing a saline-alkali land improver comprises the following steps:

[0059] 1) Immerse the activated carbon balls in a saturated solution of organic acid and stir for 2 hours, then dry to obtain acidified balls;

[0060] 2) Vibrate and stir the acidified balls and coated calcium peroxide in a weight ratio of 10:0.8 to obtain filled balls;

[0061] 3) Prepare a 5wt% solution of polyvinyl alcohol, spray it on the surface of the filled ball, and then roll and coat the super absorbent resin to obtain a coated ball. The amount of the coated super absorbent resin is 5% of the total amount of the filled ball;

[0062] 4) 1,4-butanediol was added to a 5wt% polyvinyl alcohol solution to form a mixed solution, which was sprayed on the surface of the coated ball and dried at 150°C. The coating thickness was 130 μm to obtain a modifier, wherein the amount of 1,4-butanediol added was 6% of the total amount of polyvinyl alcohol.

[0063] The organic acid is citric acid; the coated calcium peroxide is commercially available PVP-coated CaO2 powder, and the PVP coating amount is 0.2%.

[0064] Activated carbon balls are prepared by the following steps:

[0065] 1) Phenolic resin, surfactant and ethanol are mixed evenly, wood powder is added and stirred continuously to form a suspension, and then the suspension is dripped dropwise into 100° C. hot water to form spherical particles, wherein the weight ratio of the phenolic resin, surfactant, ethanol and wood powder is 2:0.2:10:1;

[0066] 2) After filtering the spherical particles, heat them at 150°C for 2 hours to obtain solidified balls;

[0067] 3) The solidified balls were heated to 650°C in a nitrogen atmosphere for pyrolysis for 1 hour, and then CO2 was introduced and the temperature was raised to 800°C for activation for 2 hours to obtain activated carbon balls with a particle size of 3 mm.

[0068] The wood powder is made by crushing wood; the surfactant is Tween 20.

[0069] Comparative Example 1

[0070] The difference between Comparative Example 1 and Example 4 is as follows:

[0071] The preparation method of activated carbon balls is as follows: activated carbon powder is sprayed into 5wt% polyvinyl alcohol adhesive to prepare activated carbon particles with a particle size of 3 mm, and the other processes are the same as those in Example 4. In step 2), 5wt% polyvinyl alcohol solution is sprayed to adhere the coated calcium peroxide, and the other processes are the same as those in Example 4.

[0072] Performance Testing

[0073] 1. The shell strength (MPa), carbonization rate (%) and ethanol adsorption capacity (mg / g) of the activated carbon balls prepared in Examples 1-4 were tested.

[0074] 2. The improvers prepared in Examples 1-4 and Comparative Example 1 were applied to the saline-alkali land improvement experiment in Changyi City, Weifang City, Shandong Province. The crops were sown on April 20, 2019, and 0-20 cm soil was taken in June 2020 to detect pH, soluble salt (g / kg), soil porosity, water holding capacity, water penetration depth (60 min, cm) and average plant height (cm) of crops.

[0075] The crop was alfalfa (Beijing Zhengdao Seed Industry), the base fertilizer was organic fertilizer (Shandong Wengfu Jingu Fertilizer Co., Ltd., organic matter>45%, N+P2O5+ K2O≥5%, 150kg / mu), the amount of improver was 80kg / mu, and the crops were harvested twice in between; the test groups 1-4 and the comparative example 1 (comparison 1) used improvers and organic fertilizers; the control group 1 did not apply improvers and organic fertilizers (the crops could not grow), and the control group 2 only applied organic fertilizers. The results are shown in Table 1.

[0076] Table 1 Performance test results

[0077] Strength MPa Carbonization rate% Ethanol adsorption mg / g pH Soluble salt Porosity% Water holding capacity% Water penetration depth cm Plant height (cm) Comparison 1 - - - 8.90 2.70 51.2 10.1 1.5 0 Comparison 2 - - - 8.35 2.13 56.7 12.5 2.0 21.4 1 0.512 66 416.3 7.54 1.40 85.6 19.6 8.1 71.5 2 0.506 60 407.8 7.33 1.38 84.3 19.2 7.5 70.4 3 0.509 64 420.6 7.46 1.30 86.2 19.5 8.1 70.8 4 0.524 61 412.4 7.65 1.42 85.1 19.8 7.8 71.2 1 - - - 8.1 1.68 65.2 14.3 3.4 54.2

[0078] From Table 1, it can be seen that the activated carbon balls prepared in the present application have a high ethanol adsorption capacity, a large number of voids on the surface and inside, and a high shell strength that is not easy to collapse and compact with the soil. Therefore, it can maintain the permeability of saline-alkali soil and increase the improvement effect.

[0079] Combined with the application experiments, it can be seen that the control group 1 did not apply the modifier and organic fertilizer, and its crops could not grow; while the control group 2 only applied organic fertilizer, and the crops could barely grow, but the biomass was relatively low; and the modifiers of Examples 1-4 of the present application can greatly improve the porosity and water holding capacity of the soil, increase the water permeability depth, thereby promoting crop growth, and improve the soil alkalinity and soluble salt content, with excellent improvement effect.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a saline-alkali land modifier, characterized in that: The following steps are involved: 1) Immerse the activated carbon balls in a saturated solution of an organic acid and stir for 2-3 hours, then dry to obtain acidified balls; 2) Vibrate and stir the acidified balls and coated calcium peroxide in a weight ratio of 10:0.5-0.8 to obtain filled balls; 3) preparing a 3-5wt% solution of polyvinyl alcohol, spraying it on the surface of the filled ball, and then rolling and coating the ball with a super absorbent resin to obtain a coated ball, wherein the amount of the coated super absorbent resin is 4-5% of the total amount of the filled ball; 4) adding 1,4-butanediol to a 3-5wt% polyvinyl alcohol solution to form a mixed solution, spraying it on the surface of the coated ball, drying it at 150°C, and the coating thickness is 100-150 μm to obtain a modifier, wherein the amount of 1,4-butanediol added is 5-6% of the total amount of polyvinyl alcohol; The activated carbon balls are prepared by the following steps: 1) mixing phenolic resin, surfactant and ethanol evenly, adding wood powder and continuing stirring to form a suspension, and then dropping the suspension into hot water to form spherical particles, wherein the weight ratio of the phenolic resin, surfactant, ethanol and wood powder is 1-2:0.2:10:1; 2) heating the spherical particles at 120-150° C. for 2 h to obtain solidified balls; 3) The solidified balls were heated to 600-650°C in a nitrogen atmosphere for pyrolysis for 1 hour, and then activated for 2 hours to obtain activated carbon balls with a particle size of 2-4 mm.

2. The method for preparing a saline-alkali land improving agent according to claim 1, characterized in that: The organic acid is citric acid or malic acid.

3. The method for preparing a saline-alkali land improving agent according to claim 1, characterized in that: The wood powder is obtained by crushing wood or fruit shell.

4. The method for preparing a saline-alkali land improving agent according to claim 1, characterized in that: The surfactant is alkylphenol polyoxyethylene ether or Tween 20.

5. The method for preparing a saline-alkali land improving agent according to claim 1, characterized in that: The activation temperature in step 3) is 700-800°C.