CN110835537A - Persistent coastal saline soil improvement salt absorbent, and preparation method and application thereof - Google Patents

Abstract

The invention relates to a lasting-effect type coastal saline soil improvement salt absorption agent and a preparation method and application thereof, and the lasting-effect type coastal saline soil improvement salt absorption agent comprises two functional components of a salt absorption component and a salt retention component, wherein the salt absorption component is prepared by sulfonating modified humic acid and an inorganic adsorption material according to the ratio of (75-85): (15-25) by weight; the storage salt component is prepared from an inorganic pore material and an organic pore filling material according to the weight ratio of (85-90): (10-15) in a weight ratio. The invention organically combines the adsorption of the inorganic adsorption material with the space storage of the inorganic porous material, and combines the physical adsorption and the chemical adsorption of the organic material to achieve the purposes of 'salt adsorption' and 'salt fixation', the organic adsorption material is combined with the inorganic adsorption material to strengthen the fixation of sodium ions, reduce the sodium ion content of the soil solution, play a role in high-efficiency salt reduction, can continuously realize the desalination and alkali inhibition of coastal saline soil, continuously improve the soil, have low cost, and are suitable for rapid mass production.

Description

A sustained-effect type coastal saline soil improvement salt-absorbing agent and its preparation method and application

technical field

The invention relates to a sustained-effect type salt-absorbing agent, in particular to a sustained-effect type salt-absorbing agent for improving coastal saline soil and a preparation method and application thereof, belonging to the technical field of soil improvement.

Background technique

Saline soil, also known as saline-alkali soil, is divided into inland saline soil and coastal saline soil. The area of saline soil in China is vast, accounting for 4.88% of the country's usable land area, of which the area of saline cultivated land reaches 920.9×10 ⁴ hm ² , accounting for 6.62% of the country's arable land area. All kinds of saline soils are distributed in China, but the coastal saline soils are the most widely distributed in almost all coastal provinces, municipalities and autonomous regions, with an area of about 211.4×10 ⁴ hm ² . The coastal plain area north of the Yangtze River is the largest coastal saline soil distribution area in my country, accounting for about half of the coastal saline soil area. Due to natural factors and the lack of persistent modifiers, about 80% of coastal saline soils in my country have not been developed and utilized so far. With the reduction of arable land in my country, especially the promotion of the construction of the "Bohai granary" project, the continuous improvement, development and utilization of coastal saline soil is imminent.

Coastal saline soils are different from inland saline soils. First, the process of salt accumulation in coastal saline soil precedes the process of soil formation (this is its unique feature), which leads to the fact that coastal saline soil is not only heavy in surface salt, but also contains high salinity in the entire section, with poor structure and groundwater. The water level is high and the mineralization degree is high. Second, because the salt of coastal saline soil mainly comes from seawater, the salt composition of soil and groundwater is the same as that of seawater. Except for a few acidic coastal sulfate saline soils, chlorides dominate, and sodium chloride dominates. most. Third, coastal saline soil is mainly affected by groundwater and seawater inversion, and the biological impact is minimal, so the soil alkalinity is low, carbonate ions are hardly detected, and the pH is mostly 7.5 to 8.0; fourth, "thin" and other obstacle factors More prominently, due to high salinity, it is difficult to fertilize, and coastal saline soil is generally lacking in nutrients. Therefore, there is an urgent need for improved technologies based on the characteristics of coastal saline soil and the utilization of resources in coastal areas.

For heavily saline soil (salt content > 0.4%), applying amendments or salt absorbing agents to reduce the salt content of the coastal saline soil topsoil can effectively avoid the double salt problem of the topsoil caused by the traditional water pressure salt pressure. .

For example, Chinese patent document CN102504825A discloses a coastal saline soil ecological improver and its preparation method and application. The improver neutralizes the alkali through the acid and alkali generated by the physiological metabolism of the bacteria to reduce the pH value of the soil. At the same time, the existence of the microbial community in the soil blocks the condition that the salt rises with the water along the capillary gap, and reduces the salt content of the topsoil. The modifier can only reduce the salt content of the topsoil, but cannot absorb salt and solidify the salt. Due to the relatively high salt content, it is easy to reduce the activity of the biological inoculum, and the improvement effect on the severely saline soil is not good.

Another example is that Chinese patent document CN105993267A discloses a method for carrying out original soil greening on coastal saline-alkali land by a salt-absorbing agent containing fly ash, and Chinese patent document CN105993268A discloses a salt-absorbing agent containing sugar slag mud for seawater-impregnated saline-alkali land. The method of soil greening, although these two literatures are salt absorbing agents, they have the following shortcomings:

(1) The immobilization of salt is unstable, especially for sodium ions. Coastal saline soil, especially severe saline soil, has more than 90% of its salt composition as sodium chloride, so it is not stable to sodium ion retention, which means that the salt absorption effect is unstable, which in turn affects the growth of crops, especially the growth of the early emergence stage. . The above two literatures mainly absorb salt through the adsorption and burrowing of inorganic materials such as bentonite, clay particles, zeolite powder, fly ash, and fish bone meal. gradually decrease or disappear.

(2) The retention of salt is not durable, and the long-term effect is poor. The above two literatures mainly absorb salt through the adsorption of organic materials such as straw powder, but with the degradation of straw powder and organic materials, the retaining effect of salt will gradually decrease or disappear.

(3) It is only applicable to the original soil greening of coastal saline soil, not applicable to field crops. It is difficult to simultaneously sow seeds and fertilizers. In addition to being unable to simultaneously sow seeds and fertilizers without granulation, the key is that the cations in the fertilizers reduce the adsorption effect of sodium ions due to the competitive adsorption of sodium ions during simultaneous sowing of seed fertilizers. In addition, there is a problem of high cost.

(4) Unable to control the problem of soil desalination and alkali-rich plate change. The desalination process of coastal saline soil is generally accompanied by an alkalization process, which in turn increases soil compaction. The above two documents, although also introduced acidic substances such as ammonium sulfate, superphosphate, etc., but the material can only release H ⁺ quickly, can not release H ⁺ slowly and gradually, so not only can not play the role of desalination and alkali suppression, but also Inhibit the adsorption of sodium ions, thereby affecting the effect of salt absorption.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a sustained-effect salt-absorbing agent for improving coastal saline soil and its preparation method and application, aiming at the deficiencies of the prior art.

The sustained-effect type coastal saline soil improvement salt-absorbing agent of the present invention simultaneously achieves the following purposes:

(1) Organically combine the adsorption of inorganic adsorbent materials with the space closure of inorganic pore materials to achieve "salt absorption" and "solid salt".

(2) Combine the physical adsorption and chemical adsorption of organic materials to achieve "salt absorption" and "solid salt".

(3) The organic adsorption material is combined with the inorganic adsorption material to strengthen the retention of sodium ions, reduce the content of sodium ions in the soil solution, and play an efficient role in reducing salt.

(4) The organic combination of inorganic pore materials and organic pore-filling materials. First, the salt is introduced into the pores, and then the salt is firmly sealed in the pores to achieve high-strength solid salt.

(5) The cost is low, suitable for rapid mass production, and can achieve "seed and fertilizer simultaneous sowing", which is convenient for popularization and application in field crops.

(6) It can continuously achieve desalination and alkali suppression of coastal saline soil, and continuously improve the soil.

In order to achieve the above object, the present invention is achieved through the following technical solutions:

A sustained-effect type salt-absorbing agent for improving coastal saline soil, comprising two functional components: a salt-absorbing component and a closed-storage component, and the weight ratio of the salt-absorbing component to the closed-storage component is: (60-90 ): (10-40), the salt-absorbing component is composed of sulfonated modified humic acid and inorganic adsorption materials in a weight ratio of (75-85): (15-25); the The closed-storage salt component is composed of inorganic pore materials and organic pore-filling materials in a weight ratio of (85-90):(10-15).

Preferably according to the present invention, the sulfonated modified humic acid is obtained by modifying humic acid in a reaction kettle at a temperature of 55-75°C in the presence of sulfuric acid, and then drying; the mass fraction of sulfuric acid is 20-75°C. 40%, and the weight ratio of humic acid to sulfuric acid is 1:5 to 10.

Further preferably, in the preparation process of sulfonated modified humic acid, after the modification reaction is completed, filtration is performed, and the filter residue is dispersed in deionized water at a solid-to-liquid ratio of 1:5, and powdered calcium carbonate is slowly added during stirring, and the pH is adjusted to 5.5. ~6.0, plate and frame pressure filtration, the filter residue is sheared and crushed, dried by blast at a temperature of 120-150° C. to a moisture content of less than 3%, and pulverized through a 1mm sieve to obtain sulfonated modified humic acid.

Further preferably, the humic acid is weathered coal or lignite, the particle size is ≥ 100 mesh, the carbon content is ≥ 50%, and the aromaticity is ≥ 40%.

Preferably according to the present invention, the inorganic adsorbent material is one or any combination of two or more selected from aluminum sulfate hexahydrate, alum, and silica gel.

Preferably according to the present invention, the salt absorption component is prepared according to the following steps:

The sulfonated modified humic acid and the inorganic adsorption material are uniformly mixed under the conditions that the temperature is less than or equal to 20° C. and the humidity is less than or equal to 50%.

Preferably according to the present invention, the inorganic pore material is one or any combination of two or more of chabazite powder, pumice powder and palygorskite powder.

Further preferred, chabazite powder pore size The particle size is ≥100 mesh, and the particle size of pumice powder and palygorskite powder is ≥100 mesh.

Preferably according to the present invention, the organic pore-filling material is one or any combination of two or more of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl methyl cellulose, and hydroxyethyl cellulose.

Preferably according to the present invention, the closed storage salt component is prepared according to the following steps:

Add distilled water to the temperature-controlled reaction kettle, heat up to 80-100°C, then slowly add organic pore-filling material at a solid-to-liquid ratio of 1:40-50 under stirring, control the temperature to 70-80°C, stir for 30 minutes, and then Under stirring, slowly add the inorganic pore material at a weight ratio of 1:5-6 to the organic pore-filling agent, control the temperature and stir for 30 minutes, then transfer it to a stainless steel container while it is still hot, put it into an ultrasonic cleaner for ultrasonic vibration for 30-60 minutes, and press the plate and frame. Filter, the filter residue is sheared and crushed, dried by blast at a temperature of 180-250° C. to a moisture content of less than 3%, and pulverized through a 2mm sieve to obtain a closed salt storage component.

Further preferably, the ultrasonic oscillation has an oscillation frequency of 60-90 kHz. Ultrasonic vibration is used to remove air in the inorganic porous material and allow the organic pore filler to enter the pores with water.

A preparation method of a sustained-effect type coastal saline soil improvement salt-absorbing agent, comprising the following steps:

The salt absorption component and the dried closed salt storage component are mixed for 10 to 20 minutes at a weight ratio of 1:1.5 to 9 under vacuum thermal drying conditions with a vacuum degree of 90 to 95 kpa and a temperature of 70 °C;

Or the salt-absorbing component and the closed-storage component are sprayed onto the salt-absorbing component in a drum granulator or disc granulator in a weight ratio of 1:1.5 to 9. , after granulation, drying and cooling.

Further preferably, the granulation particle size is 2-5 mm.

Further preferably, when drying, the inlet air temperature of the dryer is controlled at 180-250°C, and the outlet air temperature is controlled at 70-90°C.

Further preferably, the temperature of the cooled granular modifier should not exceed the natural environment temperature.

The application of sustained-acting coastal saline soil improvement salt absorbing agent in improving coastal saline soil is used for long-term improvement of high salinity coastal saline soil full ploughing layer, and the application amount is 50kg/mu ~ 200kg/mu.

Preferably according to the present invention, for the heavily saline soil with soluble salt content ≥ 0.4%, the application rate is 100kg/mu to 200kg/mu, and for medium and low-level saline soil with soluble salt content <0.4%, the application rate is 50kg/mu Mu ~ 100kg/mu.

The present invention not only introduces a low-salinity organic adsorbent, sulfonated modified humic acid, but also introduces inorganic adsorbent materials such as aluminum sulfate hexahydrate through the preparation of the salt-absorbing component. The inorganic adsorption material produces aluminum hydroxide inorganic colloid through hydrolysis, adsorbs sodium ions in the soil solution, and reduces the sodium ion content in the soil solution, but this adsorption is reversible, and the adsorbed sodium ions can also be desorbed. Humic acid enhances the adsorption of sodium ions. In addition to enhancing physical adsorption, it can also enhance chemical adsorption, strengthen the retention of sodium ions, and further reduce the sodium ion content of the soil solution, which plays a role in reducing salt. The sodium ions adsorbed by the salt absorbing agent will also be desorbed during freshwater irrigation, and the desorbed sodium ions will enter the fresh water and move to the deep soil with the water under the action of gravity. Salt absorption function. The adsorption of salt by the adsorbent is limited, and it is in the process of dynamic equilibrium. In order to further enhance the salt absorption capacity and maintain a lower salt concentration in the soil solution, which is beneficial to the growth of crops, the present invention introduces a closed salt storage group component. , a part of sodium ions and chloride ions are fixed, which effectively avoids the increase of sodium ion and chloride ion content in soil solution caused by ion exchange caused by fertilization. This is because the dry occluded salt component quickly absorbs water in the soil, and the sodium ions and chloride ions in the soil solution enter the pores of the occluded salt component with water, and the organic pore-filling material in the pores absorbs water and swells to block Pores, "sealing" sodium ions and chloride ions in the pores, so that the content of sodium ions and chloride ions in the soil solution is greatly reduced and is not affected by fertilization. In addition, through the sulfonation modification of humic acid and inorganic adsorbents or their hydrolyzed products, acid factors and calcium ions are introduced, which can reduce soil pH, replace the sodium ions adsorbed by soil, improve soil structure, and achieve continuous desalination and alkali suppression. , Change the role of the board. The raw materials used in the preparation of salt absorbing agents are all readily available and inexpensive, and are suitable for large-scale production. By introducing binding materials for granulation, seed fertilizers can be sown simultaneously, which can not only be widely used in coastal saline soil farmland improvement , and the improvement operation can be simplified.

In a word, the advantages of the present invention are that the combination of "salt absorption" and "salt fixation" can make the salt reduction effect more obvious; the synchronization of "sustaining effect" and "high efficiency" is more conducive to maintaining the soil salinity at a lower level; "desalination" Coordinated with "salt suppression and board modification", it is more conducive to the growth of crops and the improvement of soil structure; the materials are easy to obtain, the preparation is simple, the cost is low, suitable for rapid mass production, and can be used for "seed and fertilizer simultaneous sowing", The improved operation is simplified and has broad market prospects.

Detailed ways

The present invention will be further described below with reference to the embodiments. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention, but not to limit the present invention.

The raw materials used in the examples are described as follows:

Sulfuric acid: available from Nanjing Liante Chemical Co., Ltd.;

Weathered coal humic acid and lignite humic acid are available from Jinan Yunze Chemical Co., Ltd.;

Powdered calcium carbonate, available from Jingxing Xinyang Calcium Industry Co., Ltd.;

Aluminum sulfate hexahydrate, available from Jinan Shiteng Chemical Co., Ltd.;

Alum, available from Jinan Dewang Chemical Co., Ltd.;

Silica gel, available from Jinan Qunyi Chemical Co., Ltd.;

灵寿县沃川矿产品加工厂有售；Chabazite powder, specification aperture

Available at Wochuan Mineral Products Processing Factory in Lingshou County;

Pumice powder, available in Lingshou County Baifeng Mineral Products Processing Factory;

Palygorskite powder, available from Shijiazhuang Chenxi Refractory Co., Ltd.;

93% light magnesium oxide, produced and sold by Shijiazhuang Tianyu Magnesium Co., Ltd.;

Dolomite powder, available at Hengchang Mineral Products Processing Factory in Lingshou County;

Polyvinyl alcohol (1799), available from Anhui Wanwei High-Tech Co., Ltd.;

Carboxymethyl cellulose, hydroxypropyl methyl cellulose, and hydroxyethyl cellulose are available from Hebei Hengjin Chemical Technology Co., Ltd.

Embodiment 1:

A sustained-effect salt-absorbing agent for improving coastal saline soil:

(1) Preparation of salt-absorbing components:

a. Mix aluminum sulfate hexadecahydrate and silica gel at a weight ratio of 2:3 to form an inorganic adsorbent for use;

b. Add 100L of sulfuric acid with a mass fraction of 20% into the temperature-controlled reaction kettle. According to the liquid-solid volume ratio of 10:1, slowly add the weathered coal humic acid with a particle size of ≤200 mesh while stirring, and the temperature is controlled at 70 to 75 ° C, and refluxed. 4.0～4.5h, filter, the filter residue is dispersed in deionized water according to the solid-liquid ratio of 1:5, slowly add powdered calcium carbonate during stirring, adjust the pH to 5.8～6.0, stop adding, filter by plate and frame, the filter residue is sheared and broken Then, blast drying is carried out, the drying temperature is 120-125 ° C, and the drying is stopped when the moisture content is lower than 3%, and the sulfonated modified humic acid is obtained after being pulverized and passed through a 1mm sieve;

c. Physically mix 85 parts by weight of the dried sulfonated modified humic acid and 15 parts by weight of the dried inorganic adsorbent at a temperature of 30° C. and a relative humidity of less than 40% to obtain a salt absorption component.

(2) Preparation of closed storage salt components:

a, polyvinyl alcohol and carboxymethyl cellulose are mixed by weight ratio 4:1 to obtain organic pore-filling material; chabazite powder and pumice powder are mixed by weight ratio 3:1 to obtain inorganic pore-filling material, for subsequent use;

b. Add 100L of distilled water to the temperature-controlled reaction kettle, heat up to 98-100°C, then slowly add organic pore-filling material at a solid-to-liquid ratio of 1:40 under stirring, control the temperature to 78°C-80°C, and wait until all the After adding the pore-filling material of the model, stir for another 30 minutes to obtain an organic pore-filling agent, and then slowly add the inorganic pore-filling material at a weight ratio of 1:6 to the organic pore-filling agent under stirring, and then control the temperature and stir after all the materials are added. After 30min, transfer it to a stainless steel container while it is still hot, put it into an ultrasonic cleaner for ultrasonic oscillation for 60min, and the oscillation frequency is 90 kHz to remove the air in the inorganic pore material and allow the organic pore-filling agent to enter the pores with water. Preferably, the treatment liquid is subjected to plate and frame pressure filtration, and the filter residue is subjected to blast drying at 190°C after shearing and crushing. When the moisture content is lower than 3%, the drying is stopped, and the closed salt storage component is obtained after being pulverized and passed through a 2mm sieve;

(3) Preparation of sustained-effect type coastal saline soil improvement salt-absorbing agent:

First, the salt absorption component and the closed salt storage component are mixed in a weight ratio of 1.5:1, and then vacuum dried, with a vacuum degree of 90-95 kpa, a drying temperature of 70 °C, and a drying time of 20 minutes.

A long-lasting salt-absorbing agent for coastal saline soil improvement prepared in Example 1 is suitable for the improvement of high-salinity coastal saline soil full-plough layer.

Embodiment 2:

A sustained-effect salt-absorbing agent for improving coastal saline soil:

(1) Preparation of salt-absorbing components:

a. Mix alum and silica gel at a weight ratio of 1:1 to form an inorganic adsorbent for use;

b. Add 100L of sulfuric acid with a mass fraction of 30% into the temperature-controlled reaction kettle, according to the liquid-solid volume ratio of 8:1, slowly add weathered coal humic acid with a particle size of ≤200 mesh while stirring, and control the temperature to 68 ℃～73 ℃, Reflux for 5.0h～5.5h, filter, the filter residue is dispersed in deionized water at a solid-to-liquid ratio of 1:5, slowly add powdered calcium carbonate during stirring, adjust the pH to 5.6～5.8, stop adding, filter by plate and frame, and cut the filter residue. After cutting and crushing, blast drying is carried out, the drying temperature is 140 ℃ ~ 145 ℃, and the drying is stopped when the moisture content is lower than 3%, and the sulfonated modified humic acid is obtained after crushing and passing through a 1mm sieve;

c. Physically mix 80 parts by weight of the dried sulfonated modified humic acid and 20 parts by weight of the dried inorganic adsorbent at a temperature of 30° C. and a relative humidity of less than 40% to obtain a salt absorption component.

(2) Preparation of closed storage salt components:

a, polyvinyl alcohol and hydroxypropyl methylcellulose are mixed by weight ratio 2:1 to obtain organic pore-filling material; chabazite powder and pumice powder are mixed by weight ratio 2:1 to obtain inorganic pore material, for subsequent use;

b. Add 100L of distilled water to the temperature-controlled reactor, heat up to 90°C to 95°C, then slowly add organic pore-filling materials at a solid-to-liquid ratio of 1:45 under stirring, control the temperature to 75°C to 78°C, and wait until all the After adding the organic pore-filling material, stir for another 30 minutes to obtain an organic pore-filling agent, and then slowly add the inorganic pore-filling material at a weight ratio of 1:5.5 to the organic pore-filling agent under stirring, and then control the temperature after all the materials are added. Stir for 30min, then transfer it to a stainless steel container while it is still hot, put it into an ultrasonic cleaner for ultrasonic oscillation for 60min, and the oscillation frequency is 80 kHz to remove the air in the inorganic pore material and allow the organic pore-filling agent to enter the pores with water. Preferably, the treatment liquid is subjected to plate and frame pressure filtration, and the filter residue is sheared and crushed and then dried by blasting at 200 ° C. When the moisture content is lower than 3%, the drying is stopped, and the closed salt storage group is obtained after being pulverized and passed through a 2mm sieve.

(3) Preparation of sustained-effect type coastal saline soil improvement salt-absorbing agent:

First, the closed salt storage component and the salt absorption component are mixed at a weight ratio of 1:3, and then vacuum dried, with a vacuum degree of 90-95 kpa, a drying temperature of 70 °C, and a drying time of 15 minutes.

A long-lasting salt-absorbing agent for coastal saline soil improvement prepared in Example 2 is suitable for the improvement of the whole plough layer of coastal saline soil with medium and high salinity and moderate nutrition.

Embodiment 3:

A sustained-effect salt-absorbing agent for improving coastal saline soil:

(1) Preparation of salt-absorbing components:

a. Mix aluminum sulfate hexadecahydrate and silica gel at a weight ratio of 2:3 to form an inorganic adsorbent for use;

b. Add 100L of sulfuric acid with a mass fraction of 20% into the temperature-controlled reaction kettle. According to the liquid-solid volume ratio of 10:1, slowly add the weathered coal humic acid with a particle size of ≤200 mesh while stirring, and the temperature is controlled at 70 to 75 ° C, and refluxed. 4.0～4.5h, filter, the filter residue is dispersed in deionized water according to the solid-liquid ratio of 1:5, slowly add powdered calcium carbonate during stirring, adjust the pH to 5.8～6.0, stop adding, filter by plate and frame, the filter residue is sheared and broken Then, blast drying is carried out, the drying temperature is 120-125 ° C, and the drying is stopped when the moisture content is lower than 3%, and the sulfonated modified humic acid is obtained after being pulverized and passed through a 1mm sieve;

c. Physically mix 85 parts by weight of the dried sulfonated modified humic acid and 15 parts by weight of the dried inorganic adsorbent at a temperature of 30° C. and a relative humidity of less than 40% to obtain a salt absorption component.

(2) Preparation of closed storage salt components:

a, polyvinyl alcohol and carboxymethyl cellulose are mixed by weight ratio 4:1 to obtain organic pore-filling material; chabazite powder and pumice powder are mixed by weight ratio 3:1 to obtain inorganic pore-filling material, for subsequent use;

b. Add 100L of distilled water to the temperature-controlled reaction kettle, heat up to 98-100°C, then slowly add organic pore-filling material at a solid-to-liquid ratio of 1:40 under stirring, control the temperature to 78-80°C, and wait until all organic After adding the pore-filling material, stir for another 30 minutes to obtain an organic pore-filling agent, and then slowly add the inorganic pore-filling material at a weight ratio of 1:5 to the organic pore-filling agent under stirring. After all the materials are added, the temperature is controlled and stirred for 30 minutes. Then transfer it to a stainless steel container while it is still hot and put it into an ultrasonic cleaning machine for ultrasonic oscillation for 60 minutes. The oscillation frequency is 90 kHz to remove the air in the inorganic pore material and allow the organic pore filling agent to enter the pores with water. After the filter residue is sheared and crushed, the undried closed salt storage component is obtained.

(3) Preparation of sustained-effect type coastal saline soil improvement salt-absorbing agent:

In a ratio of 1:1.5 by weight of the dried closed-storage component and the adsorbed salt component, spray the undried closed-storage component in a drum granulator or disc granulator to the mixed The adsorption salt group is divided into dry material, which is granulated, dried, cooled, sieved and packaged. Requirements: When drying, the inlet air temperature of the dryer is controlled at 220-250°C, the outlet air temperature is controlled at 85-90°C, and the cooled salt-absorbing agent particles are close to room temperature. The preferred granulation particle size is 2 mm to 5 mm, and the particle size is too large or too small. After crushing, it can be used as a special salt absorbing agent for the improvement of coastal saline soil in powder form.

A long-lasting salt-absorbing agent for coastal saline soil improvement prepared in Example 3 is used in powder form for the improvement of high-salinity coastal saline soil in full tillage, and in granular form for high-salinity coastal saline soil. Improvement of planting row and ploughing layer under the condition of seed and fertilizer co-sowing.

Embodiment 4:

A sustained-effect salt-absorbing agent for improving coastal saline soil:

(1) Preparation of salt-absorbing components:

a. Mix alum and silica gel at a weight ratio of 1:1 to form an inorganic adsorbent for use;

b. Add 100L of sulfuric acid with a mass fraction of 30% into the temperature-controlled reaction kettle, according to the liquid-solid volume ratio of 8:1, slowly add weathered coal humic acid with a particle size of ≤200 mesh while stirring, and control the temperature to 68 ℃～73 ℃, Reflux for 5.0h～5.5h, filter, the filter residue is dispersed in deionized water at a solid-to-liquid ratio of 1:5, slowly add powdered calcium carbonate during stirring, adjust the pH to 5.6～5.8, stop adding, filter by plate and frame, and cut the filter residue. After cutting and crushing, blast drying is carried out, the drying temperature is 140 ℃ ~ 145 ℃, and the drying is stopped when the moisture content is lower than 3%, and the sulfonated modified humic acid is obtained after crushing and passing through a 1mm sieve;

c. Physically mix 80 parts by weight of the dried sulfonated modified humic acid and 20 parts by weight of the dried inorganic adsorbent at a temperature of 30° C. and a relative humidity of less than 40% to obtain a salt absorption component.

(2) Preparation of closed storage salt components:

a, polyvinyl alcohol and hydroxypropyl methylcellulose are mixed by weight ratio 2:1 to obtain organic pore-filling material; chabazite powder and pumice powder are mixed by weight ratio 2:1 to obtain inorganic pore material, for subsequent use;

b. Add 100L of distilled water to the temperature-controlled reactor, heat up to 90°C to 95°C, then slowly add organic pore-filling materials at a solid-to-liquid ratio of 1:45 under stirring, control the temperature to 75°C to 78°C, and wait until all the After adding the organic pore-filling material, stir for another 30 minutes to obtain an organic pore-filling agent, and then slowly add the inorganic pore-filling material at a weight ratio of 1:5.5 to the organic pore-filling agent under stirring, and then control the temperature after all the materials are added. Stir for 30min, then transfer it to a stainless steel container while it is still hot, put it into an ultrasonic cleaner for ultrasonic oscillation for 60min, and the oscillation frequency is 80 kHz to remove the air in the inorganic pore material and allow the organic pore-filling agent to enter the pores with water. Preferably, the treatment liquid is subjected to plate and frame pressure filtration, and the filter residue is sheared and crushed to obtain an undried closed salt storage fraction.

(3) Preparation of sustained-effect type coastal saline soil improvement salt-absorbing agent:

In a ratio of 1:3 by weight of the dried closed-storage component and the adsorbed salt component, spray the undried closed-storage component in a drum granulator or disc granulator to the mixed The adsorption salt group is divided into dry material, which is granulated, dried, cooled, sieved and packaged. Requirements: During drying, the inlet air temperature of the dryer is controlled at 180-210°C, the outlet air temperature is controlled at 70-75°C, and the cooled salt-absorbing agent particles are close to room temperature. The preferred granulation particle size is 2 mm to 5 mm, and the particle size is too large or too small. After crushing, it can be used as a special salt absorbing agent for the improvement of coastal saline soil in powder form.

A kind of long-lasting salt-absorbing agent for coastal saline soil improvement prepared in Example 4 is used. The powdery one is suitable for the improvement of the whole tillage layer of the medium and high salinity coastal saline soil, and the granular one is suitable for the medium and high salinity coastal saline soil. Improvement of planting row and ploughing layer under the condition of seed and fertilizer co-sowing.

Application test example:

The long-lasting coastal saline soil improvement salt-absorbing agent prepared according to the embodiment was applied to the heavily salinized coastal saline soil improvement test in Huanghekou Town, Kenli District, Dongying City, Shandong Province, and the test crop was winter wheat.

Before sowing winter wheat:

The salinity and nutrient content of the topsoil soil are as follows: the surface layer (0-20cm) soil soluble salt content is 0.48%, which is a severe saline soil (salt content ≥ 0.40%), sodium chloride content is 93%, pH 7.2, alkaline The content of nitrogen solution is 44.5mg/Kg, the content of available phosphorus is 19.8mg/Kg, and the content of available potassium is 131.1mg/Kg.

After the winter wheat harvest:

(1) Improvement effect on soil salinity and pH

The soluble salt content of the surface layer (0-20cm) decreased by 47.7-57.3%, from the heavily saline soil to the moderately saline soil, the sodium ion content in the soil decreased by 60.3-68.9%, and the chloride ion content decreased by 35.1-45.7% %, pH dropped to 6.7～7.0. The specific indicators are shown in Table 1:

Table 1 Changes of topsoil salinity and pH after winter wheat harvest

soil index Example 1 Example 2 Example 3 Example 4 Soil soluble salt content (%) 0.205 0.237 0.234 0.251 Soil soluble salt content decreased (%) 57.3 50.6 51.3 47.7 Soil sodium ion content decreased (%) 68.9 63.4 62.8 60.3 Decrease in soil chloride ion content (%) 45.7 37.9 39.7 35.1 soil pH 7.0 7.1 7.0 7.2

(2) Persistence in improving soil salinity and pH

The coastal saline soil improved by applying the salt-absorbing agent was no longer applied with the salt-absorbing agent. After 6 months, the soil soluble salt content and pH of the topsoil (0-20cm) were measured. The test results are shown in Table 2 below:

Table 2 Physicochemical properties of coastal saline soil after 6 months of salt absorption

soil index Example 1 Example 2 Example 3 Example 4 Soil soluble salt content (%) 0.207 0.241 0.235 0.256 soil pH 7.0 7.1 7.0 7.2

As can be seen from Table 2, even if the salt-absorbing agent is no longer applied to the improved coastal saline soil, the soil soluble salt content and pH remain basically unchanged after 6 months, indicating that the salt-absorbing agent of the present invention has a lasting effect. and long duration.

(3) Effects on the growth and yield of winter wheat

Compared with the control, in the wheat fields with the application of the sustained-effect coastal saline soil improvement special salt-absorbing agent, the emergence rate increased by 25.8% to 29.5%, the number of ears per mu increased by 32.1% to 36.8%, and the yield per mu of winter wheat increased by 35.9% ~42.6%. The specific indicators are shown in Table 2:

Table 3 Growth and yield of winter wheat

soil index Example 1 Example 2 Example 3 Example 4 Increase in emergence rate (%) 29.5 26.2 28.1 25.8 Increase in ear number per mu (%) 36.8 33.4 34.2 32.1 Yield increase per mu (%) 42.6 37.3 39.8 35.9

The above-mentioned specific embodiments are only exemplary, in order to enable those skilled in the art to better understand the content of the present invention, and should not be construed as limiting the protection scope of the present invention, but only improvements made according to the technical solutions of the present invention, all should fall within the protection scope of the present invention.

Claims (10)

1. A lasting effect type coastal saline soil improvement salt absorption agent comprises two functional components of a salt absorption component and a salt occlusion component, wherein the weight ratio of the salt absorption component to the salt occlusion component is as follows: (60-90): (10-40), wherein the salt absorption component is prepared from sulfonated modified humic acid and an inorganic adsorbing material according to the weight ratio of (75-85): (15-25) by weight; the storage salt component is prepared from an inorganic pore material and an organic pore filling material according to the weight ratio of (85-90): (10-15) in a weight ratio.

2. The lasting-effect coastal saline soil improvement salt absorption agent as claimed in claim 1, wherein the sulfonated modified humic acid is prepared by modifying humic acid in a reaction kettle at 55-75 ℃ in the presence of sulfuric acid and then drying; the mass fraction of the sulfuric acid is 20-40%, and the solid-liquid weight ratio of the humic acid to the sulfuric acid is 1: 5-10.

3. The lasting-effect coastal saline soil improvement salt absorption agent according to claim 1, characterized in that in the preparation process of the sulfonated modified humic acid, after the modification reaction is completed, filtration is carried out, filter residues are dispersed in deionized water according to a solid-to-liquid ratio of 1:5, powdery calcium carbonate is slowly added while stirring, the pH is adjusted to be 5.5-6.0, plate and frame filter pressing is carried out, after the filter residues are sheared and crushed, air-blast drying is carried out at a temperature of 120-150 ℃ until the water content is lower than 3%, and the filter residues are crushed by a sieve of 1mm to obtain the sulfonated modified humic acid, preferably, the humic acid is weathered coal or lignite, the particle size is larger than or equal to 100 meshes, the carbon content is larger than or equal to.

4. The lasting coastal saline soil improvement salt adsorbent of claim 1, wherein the inorganic adsorbing material is one or more of aluminum sulfate hexadecahydrate, alum and silica gel in any combination.

5. The lasting type coastal saline soil improvement salt absorption agent according to claim 1, wherein the salt absorption component is prepared by the following steps:

and uniformly mixing the sulfonated modified humic acid and the inorganic adsorbing material at the temperature of less than or equal to 20 ℃ and the humidity of less than or equal to 50 percent to obtain the humic acid modified humic acid.

6. The lasting type coastal saline soil improvement salt absorption agent as claimed in claim 1, wherein the inorganic porous material is one or more of chabazite powder, pumice powder and palygorskite powder, and the pore diameter of the chabazite powder is any combination of two or more of the chabazite powder, the pumice powder and the palygorskite powder

The grain size is more than or equal to 100 meshes, and the grain size of the pumice powder and the palygorskite powder is more than or equal to 100 meshes; the organic pore-filling material is one or more of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl methyl cellulose and hydroxyethyl cellulose.

7. The lasting coastal saline soil improvement salt absorption agent according to claim 1, wherein the salt sequestration component is prepared by the following steps:

adding distilled water into a temperature-controlled reaction kettle, heating to 80-100 ℃, then slowly adding an organic pore filling material according to a solid-to-liquid ratio of 1: 40-50 while stirring, controlling the temperature at 70-80 ℃, stirring for 30min, then slowly adding an inorganic pore material according to a weight ratio of 1: 5-6 to the organic pore filling agent while stirring, controlling the temperature and stirring for 30min, then transferring the mixture into a stainless steel container while the mixture is hot, putting the mixture into an ultrasonic cleaning machine for ultrasonic oscillation for 30-60 min, performing plate and frame filter pressing, performing air-blast drying on filter residues at 180-250 ℃ after shearing and crushing until the water content is lower than 3%, and crushing the filter residues through a 2mm sieve to obtain the occluded salt component.

8. A preparation method of a lasting type coastal saline soil improvement salt absorption agent comprises the following steps:

mixing the salt absorption component and the dried salt occlusion and storage component for 10-20 min under the vacuum heat drying condition of vacuum degree of 90-95 kpa and temperature of 70 ℃ according to the weight ratio of 1: 1.5-9;

or spraying the salt absorption component and the salt retention component in a weight ratio of 1: 1.5-9 into the salt absorption component, granulating, drying and cooling.

9. The preparation method of claim 8, wherein the grain size of the granulated material is 2-5 mm, the inlet air temperature of the dryer is controlled to be 180-250 ℃ during drying, the outlet air temperature is controlled to be 70-90 ℃, and the temperature of the cooled granular modifying agent is not higher than the natural environment temperature.

10. The application of the lasting-effect type coastal saline soil improvement salt absorption agent in improving coastal saline soil is used for long-acting improvement of a high-salinity coastal saline soil full plough layer, and the application amount is 50 kg/mu to 200 kg/mu;

the application amount is 100 kg/mu to 200 kg/mu for severe saline soil with the soluble salt content of more than or equal to 0.4 percent, and is 50 kg/mu to 100 kg/mu for medium and low-degree saline soil with the soluble salt content of less than 0.4 percent.