CN103566899A - Comprehensive treatment method for agricultural straws - Google Patents

Abstract

The invention discloses a comprehensive treatment method for agricultural straws. The agricultural straws are subjected to pretreatment, pretreatment, and carbonization to obtain liquid-phase products and solid-phase products, wherein the liquid-phase products undergo condensation and sulfonation reactions to produce water coal Slurry dispersant products, solid-phase products are modified to obtain solid adsorbent products. The invention can effectively avoid the pollution of waste liquid produced by straw treatment in the prior art, and use the lignin-rich liquid phase product as a coal-water slurry dispersant after condensation and sulfonation reactions, achieving good technical effects; At the same time, the solid adsorbent product obtained by the method of the present invention has a good adsorption effect due to precise control of the reaction process and selection of optimal process parameters, and can effectively purify anion and cation pollutants in wastewater.

Description

A comprehensive treatment method for agricultural straw

technical field

The invention relates to a straw processing method, in particular to a comprehensive processing method of agricultural straw to prepare solid adsorbent products and coal-water slurry dispersant products. the

Background technique

Since 2006, the whole country has strengthened energy conservation and emission reduction work. The State Council issued a decision to strengthen energy conservation work and formulated a series of policies and measures to promote energy conservation and emission reduction. Various regions and departments have made work arrangements one after another. Positive progress has been made. However, in 2006, the whole country failed to achieve the goals of energy saving and pollution reduction determined at the beginning of the year, which increased the difficulty of energy saving and emission reduction in the four years after the "Eleventh Five-Year Plan". What is more serious is that in the first quarter of 2007, industries, especially those with high energy consumption and high pollution, grew too fast, accounting for nearly 70% of the national industrial energy consumption and sulfur dioxide emissions, such as electricity, steel, non-ferrous metals, building materials, petroleum processing, and chemicals The six major industries grew by 20.6%, an acceleration of 6.6 percentage points year-on-year. At the same time, there are still problems such as insufficient understanding, unclear responsibilities, unsuitable measures, imperfect policies, unrealized investment, and ineffective coordination in all aspects of work. the

The national "Twelfth Five-Year Plan" clearly puts forward the goal of energy conservation and emission reduction, that is, by 2015, carbon dioxide emissions per unit of GDP will be reduced by 17%; energy consumption per unit of GDP will be reduced by 16%; the proportion of non-fossil energy in primary energy consumption will increase by 3.1 percentage points, From 8.3% to 11.4%; the goal of reducing the total discharge of major pollutants by 8 to 10%. In addition, the 12th Five-Year Plan also clarified the general categories of major pollutants to be controlled. On the basis of the two categories of chemical oxygen demand and carbon dioxide in the "Eleventh Five-Year Plan", two categories of pollutants, ammonia nitrogen and nitrogen oxides, were added. Control indicators. The binding indicators proposed in the "Twelfth Five-Year Plan" further clarified the country's determination to save energy and reduce emissions. The State Council has identified five key projects for the reduction of major pollutants: First, urban sewage treatment facilities and supporting pipe networks Focus on construction, upgrading and reconstruction of existing facilities, and construction of sludge treatment and disposal facilities to improve the capacity of nitrogen and phosphorus removal. Second, focus on pulp and paper, printing and dyeing, food processing, agricultural and sideline product processing and other industries to continue to increase the depth of water pollution Governance and technological transformation. The third is to promote the construction of desulfurization and denitrification projects. The fourth is to carry out the prevention and control of agricultural source pollution. The fifth is to control the discharge of motor vehicle pollutants. 

Agricultural straw is the general term for the stems and leaves (ears) of mature crops, and usually refers to the remaining parts of wheat, rice, corn, potatoes, oilseeds, cotton, and sugarcane after harvesting the seeds. More than half of the photosynthetic products of crops exist in straw. According to the statistics of the United Nations Environment Program (UNEP), various crops grown in the world produce up to 1.7 billion tons of straw every year. the

As a common agricultural waste in rural my country, straw has the characteristics of wide distribution and large amount of resources. According to its chemical composition, straw is mainly composed of cellulose, hemicellulose and lignin, and also contains a small amount of ash that can be extracted by neutral solvents such as water, ethanol, benzene, or dilute acid and alkaline solutions, and extractable organic matter, etc. . the

Straw is not only an important by-product of crops, but also an important production resource for industrial and agricultural production. However, at present, the treatment of straw is still mainly in the traditional aspects of burning, returning to the field, and feeding. Among them, straw burning has attracted more and more attention in recent years. According to statistics, the world's annual output of straw is about 2.9 billion tons, of which about 66% is directly returned to the field or burned as a living energy. Straw incineration will not only produce CO, SO ₂ and other toxic and harmful gases, but also produce a large amount of inhalable particulate matter, which is harmful to human health. In fact, straw burning not only brings environmental pollution, but also a serious waste of resources. Fully exploring the potential value of straw and using straw as industrial raw materials is the main development direction of straw utilization in recent years, and it should also be an important aspect of implementing the energy-saving and emission-reduction tasks of the national 12th Five-Year Plan.

In the prior art, CN102614853A prepared a kind of adsorbent with carbonaceous material as raw material, first impregnated the carbonaceous material in the metal chloride solution, dried after the impregnation was sufficient, and then put the dried mixture into the tube furnace Carry out carbonization and activation to make pores to prepare composite adsorbent; mix the carbonized and activated composite adsorbent with metal powder tin powder and aluminum powder evenly, add binder and stir evenly, then fill it into the fins of the metal finned tube, and dry; The metal finned tube with adsorbent and metal powder is put into a tube furnace for sintering, and the adsorbent and metal finned tube are sintered together by metal powder. the

CN102815699A discloses a preparation method of a novel cedar branch carbonaceous material. In order to prepare the cedar branch carbonaceous material by hydrothermal carbonization, the method comprises the following steps: collecting the fallen branches of cedar trees and peeling them; The final branch is cut into small sections, put into the water that is dissolved with appropriate amount of citric acid to carry out hydrothermal carbonization reaction, wherein the temperature of hydrothermal carbonization reaction is 180～220 ℃, and the reaction time is 28～32 hours; After the solution is naturally cooled, the solution is filtered off, the carbide is washed and then vacuum-dried; the dried carbide is ground to obtain the cedar branch carbonaceous material. the

At the same time, the prior art also discloses that the treated straw is used as an environmental protection material, such as petroleum adsorbent, heavy metal adsorbent and the like. However, there is a large amount of lignin in the waste liquid produced by the method of processing straw in the prior art, which makes it difficult to treat, forms secondary pollution, and has technical defects such as poor adsorption effect of the prepared adsorbent. A method for comprehensively treating straw. the

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a comprehensive treatment method for agricultural stalks to overcome the problem of waste liquid pollution in the prior art, and to turn waste into treasure, and to prepare a coal-water slurry dispersant and high-efficiency solid adsorbent products. the

A comprehensive processing method for agricultural stalks, characterized in that it comprises the following steps:

(1) Pretreatment: dry the agricultural stalks, cut the dried agricultural stalks into small sections and grind them further with a mixer, then pass through a 100-mesh sampling sieve, take the stalks under the sampling sieve and wash them with deionized water for 2— 3 times, then use a vacuum pump to filter until the filtrate becomes clear, and dry the obtained straw powder in a drying oven at 55°C for 24-48 hours to obtain the pretreated straw powder;

(2) Pretreatment: Swell the pretreated straw powder obtained in step (1) with 0.01-0.09mol/L sodium hydroxide solution. The swelling time is 48-64 hours. After swelling, adjust pH to 6.6-7.4, after centrifugal filtration, wash with deionized water for 2-3 times, and then place in a drying oven at 65°C for 24-48h; obtain pre-treated straw powder;

(3) Carbonization treatment: Weigh the pretreated straw powder, deionized water, and propylene oxide obtained in step (2) and add them to the reactor, seal it, and feed nitrogen gas for 20-60 minutes to discharge the residual gas inside the reactor. After tightening the air inlet and outlet valves, turn on the magnetic stirring device for stirring, and pass cooling water to protect the magnetic stirring device, and heat the reactor to 220-250°C through an electronic furnace; after reaching the reaction temperature, stop heating and let it cool naturally to 180°C, then pour in condensed water until the reactor cools down to room temperature; then open the reactor, and filter the reaction product to obtain a liquid-phase product and a solid-phase product; dry the solid-phase product at 110-120°C for 26-36 hours , to obtain the solid material after carbonization treatment; wherein the mass dosage ratio of the pretreated straw powder, deionized water, and propylene oxide obtained in step (2) is 5-20:500-1500:3-5;

(4) Modification treatment: 3-chloro-2-hydroxypropyltrimethylammonium chloride is dissolved in isopropanol-water mixed solution to form mixed solution A, and then the solid material obtained in step (3) is added In the above mixed solution A, wherein, the mass ratio of 3-chloro-2-hydroxypropyltrimethylammonium chloride, isopropanol to water is 5-10:16-23:200-230, 3-chloro- The mass ratio of 2-hydroxypropyltrimethylammonium chloride to the solid material obtained in step (3) is 1-3:5-10, and the resulting mixture is reacted for 12-20h at 30-65°C, and after the reaction finishes, the The pH of the reaction system was adjusted to 6.5-7; then the obtained solution was filtered, and the filtered solid product was washed 2-3 times with deionized water, and then dried at 110-120°C for 26-48h to obtain 3-chloro-2 -The solid product of hydroxypropyltrimethylammonium chloride modification;

Dissolve chloroacetic acid in ethanol-water mixed solution to form mixed solution B, wherein the mass ratio of chloroacetic acid, ethanol and water is 4-9:20-100:20-98, and 3-chloro-2-hydroxypropyl The solid product modified by trimethyl ammonium chloride is added in the mixed solution B, wherein, the mass ratio of the solid product modified by 3-chloro-2-hydroxypropyl trimethyl ammonium chloride to chloroacetic acid is 5— 10: 6-12; Stir and react at 40-80°C for 13-24h; after the reaction, adjust the pH of the above system to 6.6-7.5; then filter the obtained solution, and wash the filtered solid product with deionized water 5-9 times, then dry at 110-115°C for 30-72 hours to obtain solid adsorbent products;

(5) Preparation of coal water slurry dispersant: adjust the pH of the liquid phase product obtained in step (3) to 12-12.8, raise the temperature to 75°C while stirring, add formaldehyde dropwise for condensation reaction for 1-2h, and then raise the temperature To 90°C, add sodium sulfite to carry out sulfonation reaction for 2-3 hours, after the reaction is completed, cool to normal temperature and discharge to obtain the coal water slurry dispersant product. the

Further, the agricultural straw is wheat straw, rice straw, corn straw, cotton straw, or sugarcane straw. the

The comprehensive treatment method for agricultural stalks disclosed by the invention can effectively avoid the problem of waste liquid pollution caused by the treatment of stalks in the prior art. The coal water slurry dispersant has achieved good technical effects; meanwhile, the solid adsorbent product obtained by the method of the present invention has a good adsorption effect due to the precise control of the reaction process and the selection of optimal process parameters, and can treat the waste water. Effective purification of anion and cation pollutants. the

Description of drawings

Fig. 1 is a schematic flow chart of the present invention. the

Detailed ways

The present invention will be further described in detail below in conjunction with specific embodiments. the

Example 1

A comprehensive processing method for agricultural stalks, characterized in that it comprises the following steps:

(1) Pretreatment: dry the wheat straw, cut the dry wheat straw into small pieces and grind it further with a mixer, then pass through a 100-mesh sampling sieve, take the straw under the sampling sieve and wash it twice with deionized water , and then use a vacuum pump to filter until the filtrate becomes clear, and the obtained straw powder is dried in an oven at 55°C for 48 hours to obtain a pretreated straw powder;

(2) Pretreatment: Swell the pretreated straw powder obtained in step (1) with 0.01mol/L sodium hydroxide solution, the swelling time is 48 hours, after the swelling is completed, adjust the pH to 6.6, After centrifugal filtration, wash twice with deionized water, and then place in a drying oven at 65°C for 24 hours to obtain pretreated straw powder;

(3) Carbonization treatment: Weigh the pretreated straw powder, deionized water, and propylene oxide obtained in step (2) and add them to the reactor, seal it, and feed nitrogen gas for 20 minutes to discharge the residual gas inside the reactor, and then put the After the air inlet and outlet valves are tightened, turn on the magnetic stirring device for stirring, and pass cooling water to protect the magnetic stirring device, and heat the reactor to 220°C through an electronic furnace; after reaching the reaction temperature, stop heating, and first cool down to 180°C naturally. Finally, pour condensed water until the reactor is cooled to normal temperature; then open the reactor, and filter the reaction product to obtain a liquid-phase product and a solid-phase product; dry the solid-phase product at 110°C for 26 hours to obtain a carbonized solid material ; Wherein the mass dosage ratio of the pretreated stalk powder, deionized water, and propylene oxide obtained in step (2) is 5:1500:5;

(4) Modification treatment: 3-chloro-2-hydroxypropyltrimethylammonium chloride is dissolved in isopropanol-water mixed solution to form mixed solution A, and then the solid material obtained in step (3) is added Into the above mixed solution A, wherein the mass ratio of 3-chloro-2-hydroxypropyltrimethylammonium chloride, isopropanol to water is 5:23:230, 3-chloro-2-hydroxypropyltrimethylammonium The mass ratio of methyl ammonium chloride to the solid material obtained in step (3) is 1:10, and the resulting mixture is reacted for 12 hours at 30° C., and the pH of the reaction system is adjusted to 6.5 after the reaction; then the obtained solution is Filtration, the filtered solid product was washed twice with deionized water, and then dried at 110°C for 26 hours to obtain a solid product modified with 3-chloro-2-hydroxypropyltrimethylammonium chloride;

Dissolve chloroacetic acid in an ethanol-water mixed solution to form a mixed solution B, wherein the mass ratio of chloroacetic acid, ethanol and water is 4:100:98, and chlorinated 3-chloro-2-hydroxypropyl trimethyl The ammonium-modified solid product was added to the mixed solution B, wherein the mass ratio of the 3-chloro-2-hydroxypropyltrimethylammonium chloride-modified solid product to chloroacetic acid was 5:12; at 40°C Stir the reaction for 13 hours; after the reaction, adjust the pH of the above system to 6.6; then filter the obtained solution, wash the filtered solid product with deionized water for 5 times, and then dry it at 110°C for 30 hours to obtain a solid adsorbent product ;

(5) Preparation of coal water slurry dispersant: adjust the pH of the liquid phase product obtained in step (3) to 12, raise the temperature to 75°C while stirring, add dropwise formaldehyde for condensation reaction for 1 hour, then raise the temperature to 90°C, Sodium sulfite was added for sulfonation reaction for 2 hours, and after the reaction was completed, the mixture was cooled to room temperature and discharged to obtain a coal-water slurry dispersant product. the

Example 2

A comprehensive treatment method for corn stalks, characterized in that it comprises the steps of:

(1) Pretreatment: Dry the corn stalks, cut the dried corn stalks into small pieces and grind them further with a mixer, then pass through a 100-mesh sampling sieve, take the straw under the sampling sieve and wash it with deionized water for 3 times , and then use a vacuum pump to filter until the filtrate becomes clear, and the obtained straw powder is dried in an oven at 55°C for 48 hours to obtain a pretreated straw powder;

(2) Pretreatment: Swell the pretreated straw powder obtained in step (1) with 0.09 mol/L sodium hydroxide solution. The swelling time is 64 hours. After swelling, adjust the pH to 7.4. After centrifugal filtration, wash with deionized water for 3 times, then place in a drying box and dry at 65°C for 48 hours; obtain the pretreated straw powder;

(3) Carbonization treatment: Weigh the pretreated straw powder, deionized water, and propylene oxide obtained in step (2) and add them to the reactor, seal it, and feed nitrogen gas for 60 minutes to discharge the residual gas inside the reactor, and then put the After the air inlet and outlet valves are tightened, turn on the magnetic stirring device for stirring, and pass cooling water to protect the magnetic stirring device, and heat the reactor to 250°C through an electronic furnace; after reaching the reaction temperature, stop heating, and first cool down to 180°C naturally. Finally, pour condensed water until the reactor is cooled to normal temperature; then open the reactor, and filter the reaction product to obtain a liquid-phase product and a solid-phase product; dry the solid-phase product at 120°C for 36 hours to obtain a carbonized solid material ; Wherein the mass consumption ratio of the pretreated stalk powder, deionized water and propylene oxide obtained in step (2) is 20:500:3;

(4) Modification treatment: 3-chloro-2-hydroxypropyltrimethylammonium chloride is dissolved in isopropanol-water mixed solution to form mixed solution A, and then the solid material obtained in step (3) is added Into the above mixed solution A, wherein the mass ratio of 3-chloro-2-hydroxypropyltrimethylammonium chloride, isopropanol to water is 10:16:200, 3-chloro-2-hydroxypropyltrimethylammonium The mass ratio of methyl ammonium chloride to the solid material obtained in step (3) is 3:5, and the resulting mixture is reacted for 20 h at 65° C., and the pH of the reaction system is adjusted to 7 after the reaction; Filtration, the filtered solid product was washed 3 times with deionized water, and then dried at 120°C for 48h to obtain a solid product modified with 3-chloro-2-hydroxypropyltrimethylammonium chloride;

Dissolve chloroacetic acid in ethanol-water mixed solution to form mixed solution B, wherein the mass ratio of chloroacetic acid, ethanol and water is 9:20:20, and chlorinated 3-chloro-2-hydroxypropyl trimethyl Add the ammonium-modified solid product to the mixed solution B, wherein the mass ratio of the 3-chloro-2-hydroxypropyltrimethylammonium chloride-modified solid product to chloroacetic acid is 10:6; at 80°C Stir the reaction for 24 hours; after the reaction, adjust the pH of the above system to 7.5; then filter the obtained solution, wash the filtered solid product with deionized water for 9 times, and then dry it at 115°C for 72 hours to obtain a solid adsorbent product;

(5) Preparation of coal water slurry dispersant: adjust the pH of the liquid phase product obtained in step (3) to 12.8, raise the temperature to 75°C while stirring, add dropwise formaldehyde for condensation reaction for 2 hours, then raise the temperature to 90°C, Sodium sulfite was added for sulfonation reaction for 3 hours, and after the reaction was completed, the mixture was cooled to room temperature and discharged to obtain a coal-water slurry dispersant product. the

Example 3

A comprehensive processing method for sugarcane stalks, characterized in that it comprises the following steps:

(1) Pretreatment: dry the sugarcane stalks, cut the dried sugarcane stalks into small pieces and grind them further with a mixer, then pass through a 100-mesh sampling sieve, take the straw under the sampling sieve and wash it with deionized water for 3 times , and then use a vacuum pump to filter until the filtrate becomes clear, and the obtained straw powder is dried in an oven at 55°C for 48 hours to obtain a pretreated straw powder;

(2) Pretreatment: Swell the pretreated straw powder obtained in step (1) with 0.08 mol/L sodium hydroxide solution, and the swelling time is 50 hours. After swelling, adjust the pH to 7. After centrifugal filtration, wash with deionized water for 3 times, and then place in a drying box and dry at 65°C for 40 hours; obtain the pretreated straw powder;

(3) Carbonization treatment: Weigh the pretreated straw powder, deionized water, and propylene oxide obtained in step (2) and add them to the reactor, seal it, and feed nitrogen gas for 40 minutes to discharge the residual gas inside the reactor, and then put the After the air inlet and outlet valves are tightened, turn on the magnetic stirring device for stirring, and pass cooling water to protect the magnetic stirring device, and heat the reaction kettle to 240°C through an electronic furnace; after reaching the reaction temperature, stop heating, and first cool down to 180°C naturally. After that, condensed water was introduced until the reactor was cooled to normal temperature; then the reactor was opened, and the reaction product was filtered with suction to obtain a liquid-phase product and a solid-phase product; the solid-phase product was dried at 114°C for 30 hours to obtain a carbonized solid material ; Wherein the mass dosage ratio of the pretreated stalk powder, deionized water, and propylene oxide obtained in step (2) is 15:600:4;

(4) Modification treatment: 3-chloro-2-hydroxypropyltrimethylammonium chloride is dissolved in isopropanol-water mixed solution to form mixed solution A, and then the solid material obtained in step (3) is added Into the above mixed solution A, wherein the mass ratio of 3-chloro-2-hydroxypropyltrimethylammonium chloride, isopropanol to water is 8:20:210, 3-chloro-2-hydroxypropyltrimethylammonium The mass ratio of methyl ammonium chloride to the solid material obtained in step (3) is 2:6, and the resulting mixture is reacted for 16 hours at 50° C., and the pH of the reaction system is adjusted to 6.8 after the reaction; then the obtained solution is Filtration, the filtered solid product was washed 3 times with deionized water, and then dried at 115°C for 30h to obtain a solid product modified with 3-chloro-2-hydroxypropyltrimethylammonium chloride;

Dissolve chloroacetic acid in ethanol-water mixed solution to form mixed solution B, wherein the mass ratio of chloroacetic acid, ethanol and water is 8:50:60, and chlorinated 3-chloro-2-hydroxypropyl trimethyl The ammonium-modified solid product was added to the mixed solution B, wherein the mass ratio of the 3-chloro-2-hydroxypropyltrimethylammonium chloride-modified solid product to chloroacetic acid was 7:10; at 70°C Stir the reaction for 20 hours; after the reaction, adjust the pH of the above system to 7; then filter the obtained solution, wash the filtered solid product with deionized water for 8 times, and then dry it at 112°C for 30-72 hours to obtain a solid adsorbent product;

(5) Preparation of coal-water slurry dispersant: adjust the pH of the liquid phase product obtained in step (3) to 12.6, raise the temperature to 75°C while stirring, add formaldehyde dropwise for condensation reaction for 2 hours, and then raise the temperature to 90°C, Sodium sulfite was added to carry out sulfonation reaction for 1.6 hours. After the reaction was completed, it was cooled to room temperature and discharged to obtain a coal-water slurry dispersant product. the

The solid adsorbent product obtained in Examples 1-3 was subjected to an adsorption test on copper ions in wastewater, and the results after the adsorption test are shown in Table 1. Table 1 is the adsorption test results of Examples 1-3 to copper ions in wastewater. the

It can be seen from Table 1 that the solid adsorbent products prepared in Examples 1-3 of the present invention have good adsorption effects on copper ions in wastewater. the

Although the foregoing embodiment has described the present invention in detail, it is only a part of the embodiments of the present invention, rather than all embodiments, and people can also obtain other embodiments according to the present embodiment without inventive step, these embodiments All belong to the protection scope of the present invention. the

Claims (2)

1. A comprehensive processing method for agricultural stalks, comprising the steps of: (1) Pretreatment: dry the agricultural stalks, cut the dried agricultural stalks into small sections and grind them further with a mixer, then pass through a 100-mesh sampling sieve, take the stalks under the sampling sieve and wash them with deionized water for 2— 3 times, and then use a vacuum pump to filter until the filtrate becomes clear, and dry the obtained straw powder in a drying oven at 55°C for 24-48 hours to obtain a pretreated straw powder. (2) Pretreatment: Swell the pretreated straw powder obtained in step (1) with 0.01-0.09mol/L sodium hydroxide solution. The swelling time is 48-64 hours. After swelling, adjust pH to 6.6-7.4, centrifugal filtration, washing with deionized water for 2-3 times, and then placing in a drying oven at 65° C. for 24-48 hours to obtain pretreated straw powder. (3) Carbonization treatment: Weigh the pretreated straw powder, deionized water, and propylene oxide obtained in step (2) and add them to the reactor, seal it, and feed nitrogen gas for 20-60 minutes to discharge the residual gas inside the reactor. After tightening the air inlet and outlet valves, turn on the magnetic stirring device for stirring, and pass cooling water to protect the magnetic stirring device, and heat the reactor to 220-250°C through an electronic furnace; after reaching the reaction temperature, stop heating and let it cool naturally to 180°C, then pour in condensed water until the reactor cools down to room temperature; then open the reactor, and filter the reaction product to obtain a liquid-phase product and a solid-phase product; dry the solid-phase product at 110-120°C for 26-36 hours , to obtain a carbonized solid material; wherein the mass dosage ratio of the pretreated straw powder obtained in step (2), deionized water, and propylene oxide is 5-20:500-1500:3-5. (4) Modification treatment: 3-chloro-2-hydroxypropyltrimethylammonium chloride is dissolved in isopropanol-water mixed solution to form mixed solution A, and then the solid material obtained in step (3) is added In the above mixed solution A, wherein, the mass ratio of 3-chloro-2-hydroxypropyltrimethylammonium chloride, isopropanol to water is 5-10:16-23:200-230, 3-chloro- The mass ratio of 2-hydroxypropyltrimethylammonium chloride to the solid material obtained in step (3) is 1-3:5-10, and the resulting mixture is reacted for 12-20h at 30-65°C, and after the reaction finishes, the The pH of the reaction system was adjusted to 6.5-7; then the obtained solution was filtered, and the filtered solid product was washed 2-3 times with deionized water, and then dried at 110-120°C for 26-48h to obtain 3-chloro-2 - a solid product modified by hydroxypropyltrimethylammonium chloride; Dissolve chloroacetic acid in ethanol-water mixed solution to form mixed solution B, wherein the mass ratio of chloroacetic acid, ethanol and water is 4-9:20-100:20-98, and 3-chloro-2-hydroxypropyl The solid product modified by trimethyl ammonium chloride is added in the mixed solution B, wherein, the mass ratio of the solid product modified by 3-chloro-2-hydroxypropyl trimethyl ammonium chloride to chloroacetic acid is 5— 10:6-12; Stir and react at 40-80°C for 13-24h; after the reaction, adjust the pH of the above system to 6.6-7.5; then filter the obtained solution, and wash the filtered solid product with deionized water 5-9 times, and then dry at 110-115°C for 30-72 hours to obtain a solid adsorbent product. (5) Preparation of coal water slurry dispersant: adjust the pH of the liquid phase product obtained in step (3) to 12-12.8, raise the temperature to 75°C while stirring, add formaldehyde dropwise for condensation reaction for 1-2h, and then raise the temperature To 90°C, add sodium sulfite to carry out sulfonation reaction for 2-3 hours, after the reaction is completed, cool to normal temperature and discharge to obtain the coal water slurry dispersant product. 2. The method according to claim 1, wherein the agricultural straw is wheat straw, rice straw, corn straw, cotton straw, or sugarcane straw.

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