Polyacrylamide derivative and application thereof in saline-alkali soil improvement

Abstract

The invention discloses a polyacrylamide derivative and application thereof in saline-alkali soil improvement, and relates to the technical field of soil improvement. The preparation method of the polyacrylamide derivative comprises the following steps: (1) mixing and dissolving water, sodium sulfate, ammonium sulfate and PEG; (2) adding acrylamide, disproportionated rosin resin acid vinyl ester and methacrylic acid, and completely dissolving; and (3) dissolving ammonium persulfate, potassium bromate and sodium hydrogen sulfite in water, mixing with the substances, heating to 50-70 DEG C, carrying out heat preservation reaction for 5-12 hours, and drying the obtained product to obtain the polyacrylamide derivative. The polyacrylamide derivative disclosed by the invention is polymerized by adopting specific monomers, so that the salt-reducing and alkali-reducing effects of the polyacrylamide derivative are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of soil improvement, and in particular to polyacrylamide derivatives and applications thereof in improving saline-alkali land. Background Art

[0002] The essence of the formation of saline-alkali land is mainly the horizontal and vertical redistribution of various soluble salts on the ground, so that the salt gradually accumulates on the soil surface. The improvement measures of saline-alkali land mainly include: water conservancy improvement, chemical improvement, biological improvement and agricultural improvement.

[0003] Water conservancy improvement measures use drip irrigation, flood irrigation, drainage, leaching and other methods to wash and drain salt from saline-alkali land, thereby reducing the salt content in the soil surface and creating an environment conducive to crop growth. The disadvantage is that the project is relatively complex. Agricultural improvement measures are mainly based on tillage, including deep plowing and loosening, land leveling, soil replacement, terrain elevation, micro-area soil improvement, surface covering and other measures to improve the soil and create suitable growth conditions for crops. Biological improvement is the screening or cultivation of salt-tolerant plants, microorganisms, and animals, relying on the interaction between plants, microorganisms and animals and soil salt to reduce the salt content of the soil. This method takes a long time to take effect and is difficult to meet the needs of improvement in a short period of time. Chemical improvement measures refer to the process of improving saline-alkali land by applying soil conditioners and other substances to saline-alkali land. It usually takes a fast effect and is simple to operate.

[0004] Polyacrylamide (PAM) and its derivatives are a new type of fine and functional polymer products, and are the most important varieties in modern synthetic water-soluble polymer polyelectrolytes. They are usually high molecular weight polymers obtained by free radical polymerization of monomer acrylamide (AM). For PAM derivatives, commonly used copolymer monomers are: acrylic acid, methacrylic acid, maleic anhydride, styrene sulfonic acid, vinyl sulfonic acid, propylene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate and their quaternary ammonium salts and diallyldimethylammonium chloride, etc. Acrylamide can also be copolymerized with styrene and some nitrogen heterocyclic monomers. The production method can adopt the method of producing acrylamide homopolymer.

[0005] At present, due to the good adhesion and flocculation of PAM and its derivatives, applying them to the soil can significantly improve the physical properties of the soil and has good application value. At present, there is still a lack of polyacrylamide derivatives for improving saline-alkali soil. Summary of the invention

[0006] In view of this, the purpose of the present invention is to provide a polyacrylamide derivative and its application in saline-alkali land improvement, and to improve the salt and alkali reducing effects of the polyacrylamide derivative by polymerizing specific monomers.

[0007] To achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows:

[0008] In one aspect, the present invention provides a polyacrylamide derivative, the preparation method of which comprises the following steps:

[0009] (1) Mix and dissolve water, sodium sulfate, ammonium sulfate, and PEG to obtain a mixture 1;

[0010] (2) adding acrylamide, disproportionated rosin resin acid vinyl ester, and methacrylic acid to mixture 1 and dissolving them completely to obtain mixture 2;

[0011] (3) Dissolve ammonium persulfate, potassium bromate and sodium bisulfite in water, mix with mixture 2, raise the temperature to 50-70° C. and keep the temperature to react for 5-12 hours, and dry the obtained product to obtain a polyacrylamide derivative.

[0012] Preferably, in step (1), the amount of sodium sulfate added is 1-3 kg, more preferably 1.5 kg, based on 25 kg of water.

[0013] Preferably, in step (1), based on 25 kg of water, the amount of ammonium sulfate added is 1-3 kg, more preferably 1.5 kg.

[0014] Preferably, in step (1), based on 25 kg of water, the amount of PEG added is 0.1-0.5 kg, more preferably 0.3 kg.

[0015] Preferably, in step (2), the amount of acrylamide added is 5-10 kg, more preferably 6 kg, based on 25 kg of water.

[0016] Preferably, in step (2), the amount of disproportionated rosin resin acid vinyl ester added is 0.3-1 kg, more preferably 1 kg, based on 25 kg of water.

[0017] Preferably, in step (2), the amount of methacrylic acid added is 0.5-3 kg, more preferably 2 kg, based on 25 kg of water.

[0018] Preferably, in step (2), the mass ratio of acrylamide, disproportionated rosin resin acid vinyl ester and methacrylic acid is 5-10:0.5-1:1.5-2.5, and more preferably 6:1:2.

[0019] Preferably, in step (3), the mass ratio of ammonium persulfate, potassium bromate and sodium bisulfite is 1-2:1-2:1-2, more preferably 1:1:1.

[0020] Preferably, in step (3), the temperature is raised to 57° C. and the reaction is maintained for 10 hours.

[0021] As a preferred example of the present invention, the method for preparing the anionic polymer comprises the following steps:

[0022] (1) In a 50L stainless steel reactor equipped with a stirrer, a thermometer, and a reflux condenser, first add 25kg of purified water, then add 1.5kg of sodium sulfate, 1.5kg of ammonium sulfate, and 0.3kg of PEG, and stir thoroughly to dissolve them completely;

[0023] (2) Add 6 kg acrylamide, 1 kg disproportionated rosin resin acid vinyl ester, and 2 kg methacrylic acid, stir until completely dissolved, introduce nitrogen for 30 minutes, and raise the temperature in the reactor to 35° C.;

[0024] (3) Weigh 0.5 g of ammonium persulfate, 0.5 g of potassium bromate, and 0.5 g of sodium bisulfite, add 50 mL of water to dissolve, slowly add to a reaction kettle, raise the temperature to 57° C. and keep the temperature to react for 10 hours. The obtained product is spray-dried to obtain a polyacrylamide derivative.

[0025] Preferably, the molecular weight of the polyacrylamide derivative is 4-6 million, more preferably 4.5-5 million.

[0026] In yet another aspect, the present invention provides use of the polyacrylamide derivatives in improving saline-alkali land.

[0027] Preferably, in the application, the anionic polyacrylamide polymer is used in the form of dry spreading or spraying.

[0028] The beneficial effects of the present invention are:

[0029] The invention prepares a polyacrylamide derivative by polymerizing acrylamide, disproportionated rosin resin acid vinyl ester and methacrylic acid. After the reaction, a rosin tricyclic structure is introduced into the polymer side chain and cross-linked with methacrylic acid to form a brush-like substance, which is conducive to chelating a large amount of insoluble calcium salts and preventing salt migration. At the same time, it wraps water to prevent water loss, improves soil structure, reduces salt and alkali, and specifically improves the improvement effect of saline-alkali land. DETAILED DESCRIPTION

[0030] In order to make the technical means, creative features, purpose and efficacy of the present invention easy to understand, the present invention is further explained in conjunction with specific embodiments below, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work all belong to the protection scope of the present invention. In the following embodiments, unless otherwise specified, the operating methods used are conventional operating methods, the equipment used are conventional equipment, and the equipment materials used in each embodiment are the same.

[0031] In the following examples, the molecular weight of commercially available anionic polyacrylamide is 6 million, CAS: 62649-23-4. Sodium humate was purchased from Jinan Hongtu Chemical; sodium lignosulfonate was purchased from Hefeiheng; furfural residue was purchased from Hebei Wangniu Agriculture; and diatomaceous earth was purchased from Hebei Xinxu.

[0032] Example 1

[0033] (1) In a 50L stainless steel reactor equipped with a stirrer, a thermometer, and a reflux condenser, first add 25kg of purified water, then add 1.5kg of sodium sulfate, 1.5kg of ammonium sulfate, and 0.3kg of PEG, and stir thoroughly to dissolve them completely;

[0034] (2) Add 6 kg acrylamide, 1 kg disproportionated rosin resin acid vinyl ester, and 2 kg methacrylic acid, stir until completely dissolved, introduce nitrogen for 30 minutes, and raise the temperature in the reactor to 35° C.;

[0035] (3) Weigh 0.5 g of ammonium persulfate, 0.5 g of potassium bromate, and 0.5 g of sodium bisulfite, add 50 mL of water to dissolve, slowly add to a reaction kettle, raise the temperature to 57° C. and keep the temperature to react for 10 hours. The obtained product is spray-dried to obtain a polyacrylamide derivative.

[0036] Example 2

[0037] (1) In a 50L stainless steel reactor equipped with a stirrer, a thermometer, and a reflux condenser, first add 25kg of purified water, then add 3kg of sodium sulfate, 3kg of ammonium sulfate, and 0.5kg of PEG, and stir thoroughly to dissolve them completely;

[0038] (2) Add 10 kg of acrylamide, 1 kg of disproportionated rosin resin acid vinyl ester, and 2.5 kg of methacrylic acid, stir until completely dissolved, introduce nitrogen for 30 minutes, and raise the temperature in the reactor to 35° C.;

[0039] (3) Weigh 0.8 g of ammonium persulfate, 0.4 g of potassium bromate, and 0.4 g of sodium bisulfite, add 50 mL of water to dissolve, slowly add to a reaction kettle, raise the temperature to 50° C. and keep the temperature for 12 hours. The obtained product is spray-dried to obtain a polyacrylamide derivative.

[0040] Example 3

[0041] (1) In a 50L stainless steel reactor equipped with a stirrer, a thermometer, and a reflux condenser, first add 25kg of purified water, then add 1kg of sodium sulfate, 1kg of ammonium sulfate, and 0.1kg of PEG, and stir thoroughly to dissolve them completely;

[0042] (2) Add 5 kg of acrylamide, 0.3 kg of disproportionated rosin resin acid vinyl ester, and 0.5 kg of methacrylic acid, stir until completely dissolved, introduce nitrogen for 30 minutes, and raise the temperature in the reactor to 35° C.;

[0043] (3) Weigh 0.3 g of ammonium persulfate, 0.3 g of potassium bromate, and 0.3 g of sodium bisulfite, add 50 mL of water to dissolve, slowly add to a reaction kettle, raise the temperature to 70° C. and keep the temperature to react for 5 hours. The obtained product is spray-dried to obtain a polyacrylamide derivative.

[0044] Comparative Example 1

[0045] (1) In a 50L stainless steel reactor equipped with a stirrer, a thermometer, and a reflux condenser, first add 25kg of purified water, then add 1.5kg of sodium sulfate, 1.5kg of ammonium sulfate, and 0.3kg of PEG, and stir thoroughly to dissolve them completely;

[0046] (2) Add 6 kg of acrylamide and 2 kg of methacrylic acid, stir until completely dissolved, introduce nitrogen for 30 minutes, and raise the temperature in the reactor to 35°C;

[0047] (3) Weigh 0.5 g of ammonium persulfate, 0.5 g of potassium bromate, and 0.5 g of sodium bisulfite, add 50 mL of water to dissolve, slowly add to a reaction kettle, raise the temperature to 57° C. and keep the temperature to react for 10 hours. The obtained product is spray-dried to obtain a polyacrylamide derivative.

[0048] Comparative Example 2

[0049] (1) In a 50L stainless steel reactor equipped with a stirrer, a thermometer, and a reflux condenser, first add 25kg of purified water, then add 1.5kg of sodium sulfate, 1.5kg of ammonium sulfate, and 0.3kg of PEG, and stir thoroughly to dissolve them completely;

[0050] (2) Add 6 kg acrylamide, 1 kg dimethylaminoethyl methacrylate, and 2 kg methacrylic acid, stir until completely dissolved, introduce nitrogen for 30 minutes, and raise the temperature in the reactor to 35° C.;

[0051] (3) Weigh 0.5 g of ammonium persulfate, 0.5 g of potassium bromate, and 0.5 g of sodium bisulfite, add 50 mL of water to dissolve, slowly add to a reaction kettle, raise the temperature to 57° C. and keep the temperature to react for 10 hours. The obtained product is spray-dried to obtain a polyacrylamide derivative.

[0052] Comparative Example 3

[0053] (1) In a 50L stainless steel reactor equipped with a stirrer, a thermometer, and a reflux condenser, first add 25kg of purified water, then add 1.5kg of sodium sulfate, 1.5kg of ammonium sulfate, and 0.3kg of PEG, and stir thoroughly to dissolve them completely;

[0054] (2) Add 6 kg of acrylamide, 1 kg of disproportionated rosin resin acid vinyl ester, and 2 kg of dimethylaminoethyl methacrylate, stir until completely dissolved, introduce nitrogen for 30 minutes, and raise the temperature in the reactor to 35° C.;

[0055] (3) Weigh 0.5 g of ammonium persulfate, 0.5 g of potassium bromate, and 0.5 g of sodium bisulfite, add 50 mL of water to dissolve, slowly add to a reaction kettle, raise the temperature to 57° C. and keep the temperature to react for 10 hours. The obtained product is spray-dried to obtain a polyacrylamide derivative.

[0056] Comparative Example 4

[0057] (1) In a 50L stainless steel reactor equipped with a stirrer, a thermometer, and a reflux condenser, first add 25kg of purified water, then add 1.5kg of sodium sulfate, 1.5kg of ammonium sulfate, and 0.3kg of PEG, and stir thoroughly to dissolve them completely;

[0058] (2) Add 6 kg acrylamide, 2 kg disproportionated rosin resin acid vinyl ester, and 1 kg methacrylic acid, stir until completely dissolved, introduce nitrogen for 30 minutes, and raise the temperature in the reactor to 35° C.;

[0059] (3) Weigh 0.5 g of ammonium persulfate, 0.5 g of potassium bromate, and 0.5 g of sodium bisulfite, add 50 mL of water to dissolve, slowly add to a reaction kettle, raise the temperature to 57° C. and keep the temperature to react for 10 hours. The obtained product is spray-dried to obtain a polyacrylamide derivative.

[0060] Results

[0061] 1. Polymer index

[0062] Testing method: Molecular weight and monomer residue were determined according to GB / T 17514-2017. The results are as follows:

[0063]

[0064] The results show that the residual monomers in Comparative Examples 3 and 4 are greater.

[0065] 2. Inspection of the effect of saline-alkali land improvement

[0066] The salt and alkali reduction effects of the polyacrylamide derivatives prepared in the examples and comparative examples were determined by pot tests. The experiment used a Vashvili pot, and the soil was from saline-alkali soil in the Ordos area of ​​the Inner Mongolia Autonomous Region, which was sieved through a 2 mm sieve and air-dried for later use. The initial pH value of the soil was 9.56 and the salt content of the soil was 6.53 g / kg.

[0067] Commercially available anionic polyacrylamide, polyacrylamide derivatives prepared in Examples 1-3 and Comparative Examples 1-4 were respectively mixed uniformly with the remaining ingredients according to the following formula to prepare a soil remediation agent: 80 parts of desulfurized gypsum, 5 parts of sodium humate, 6 parts of sodium lignosulfonate, 20 parts of furfural residue, 17 parts of diatomaceous earth, and 8 parts of polyacrylamide derivatives.

[0068] Soil remediation agent No. 0: no polymer added (80 parts of desulfurized gypsum, 5 parts of sodium humate, 6 parts of sodium lignosulfonate, 20 parts of furfural residue, 17 parts of diatomaceous earth);

[0069] Soil remediation agent No. 1: the polyacrylamide derivative prepared in Example 1;

[0070] Soil remediation agent No. 2: the polyacrylamide derivative prepared in Example 2;

[0071] Soil remediation agent No. 3: the polyacrylamide derivative prepared in Example 3;

[0072] Soil remediation agent No. 4: the polyacrylamide derivative prepared in Comparative Example 1;

[0073] Soil remediation agent No. 5: polyacrylamide derivative prepared in Comparative Example 2;

[0074] Soil remediation agent No. 6: polyacrylamide derivative prepared in Comparative Example 3;

[0075] Soil remediation agent No. 7: polyacrylamide derivative prepared in Comparative Example 4;

[0076] Soil remediation agent No. 8: commercially available anionic polyacrylamide.

[0077] Each soil remediation agent was fully mixed with the test soil, and potted. Each pot contained 15 kg of test soil and 2 g of soil remediation agent. A blank group was set up without adding soil remediation agent. After potting, water was poured until the soil reached saturated water holding capacity, and sowed (corn, Zhengdan 958), 10 seeds per pot. After sowing, the surface was covered with about 0.5 cm of dry soil, and the humidity was maintained at 70% of the field water holding capacity. The seedlings were fixed at the three-leaf stage, 3 plants per pot, and the aboveground weight and root weight of the corn (drying weighing method), soil pH value and salt content (conductivity method) were measured at the harvest time. The results are as follows:

[0078] Soil remediation agent number Soil pH Salt content (g / kg) Plant height(cm) Single bud fresh weight (g / plant) 0 8.74 5.87 166 235 1 7.95 2.50 222 304 2 7.93 2.82 214 287 3 7.95 2.79 210 283 4 8.37 4.10 195 268 5 8.65 5.41 178 246 6 8.06 4.95 197 275 7 8.20 5.03 191 267 8 8.65 5.53 172 244 Blank Group 9.49 6.57 151 218

[0079] The results of the potted plant test show that after adding the polyacrylamide derivatives prepared in Examples 1-3, compared with the soil remediation agent No. 0 obtained without adding the polymer, the salt and alkali reduction effects are significantly improved, indicating that the polyacrylamide derivatives can be used in saline-alkali land improvement, and its improvement effect is also significantly better than that of commercially available polyacrylamide (soil remediation agent No. 8). Comparative Examples 1 and 2 do not introduce disproportionated rosin resin acid vinyl ester monomers, and their soil remediation abilities are significantly different from those of Examples 1-3. Comparative Example 3 uses disproportionated rosin resin acid vinyl ester monomers and dimethylaminoethyl methacrylate for modification, and it is difficult to form an ideal brush-like object. Compared with Examples 1-3, the chelating ability decreases. Comparative Example 4 is also significantly different from Example 1, indicating that the monomer ratio needs to be controlled within a reasonable range.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A polyacrylamide derivative, characterized in that: The preparation method comprises the following steps: (1) Mix and dissolve water, sodium sulfate, ammonium sulfate, and PEG to obtain a mixture 1; (2) adding acrylamide, disproportionated rosin resin acid vinyl ester, and methacrylic acid to mixture 1 and dissolving them completely to obtain mixture 2; (3) Dissolve ammonium persulfate, potassium bromate and sodium bisulfite in water, mix with mixture 2, raise the temperature to 50-70° C. and keep the temperature to react for 5-12 hours, and dry the obtained product to obtain a polyacrylamide derivative.

2. The polyacrylamide derivative according to claim 1, characterized in that: In step (1), based on 25 kg of water, the amount of sodium sulfate added is 1-3 kg, the amount of ammonium sulfate added is 1-3 kg, and the amount of PEG added is 0.1-0.5 kg.

3. The polyacrylamide derivative according to claim 1, characterized in that: In step (2), based on 25 kg of water, the amount of acrylamide added is 5-10 kg, the amount of disproportionated rosin resin acid vinyl ester added is 0.3-1 kg, and the amount of methacrylic acid added is 0.5-3 kg.

4. The polyacrylamide derivative according to claim 3, characterized in that: In step (2), based on 25 kg of water, the amount of acrylamide added is 6 kg, the amount of disproportionated rosin resin acid vinyl ester added is 1 kg, and the amount of methacrylic acid added is 2 kg.

5. The polyacrylamide derivative according to claim 1, characterized in that: In step (2), the mass ratio of acrylamide, disproportionated rosin resin acid vinyl ester and methacrylic acid is 5-10:0.5-1:1.5-2.

5.

6. The polyacrylamide derivative according to claim 1, characterized in that: In step (2), the mass ratio of acrylamide, disproportionated rosin resin acid vinyl ester and methacrylic acid is 6:1:

2.

7. The polyacrylamide derivative according to claim 1, characterized in that: In step (3), the mass ratio of ammonium persulfate, potassium bromate and sodium bisulfite is 1-2:1-2:1-2.

8. The polyacrylamide derivative according to claim 1, characterized in that: In step (3), the temperature is raised to 57° C. and the reaction is maintained for 10 hours.

9. The polyacrylamide derivative according to claim 1, characterized in that: The molecular weight of the polyacrylamide derivative is 4-6 million.

10. Use of the polyacrylamide derivative according to any one of claims 1 to 9 in improving saline-alkali land.

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