Application of potassium carboxymethyl cellulose

Abstract

The invention discloses application of potassium carboxymethyl cellulose, the potassium carboxymethyl cellulose is used as a soil water-retaining agent, the substitution degree of the potassium carboxymethyl cellulose is 0.6-2.2, and the substitution uniformity is 0.501-1.

Description

Technical Field

[0001] The invention relates to the technical field of application research of carboxymethyl cellulose, and in particular to the application of potassium carboxymethyl cellulose as a water retaining agent. Background Art

[0002] Natural cellulose is the most widely distributed and abundant polysaccharide in nature. The current cellulose modification technology mainly focuses on etherification and esterification. Carboxymethylation reaction is a kind of etherification technology. Cellulose is carboxymethyl cellulose after carboxymethylation. Because of the different alkalis used in the subsequent neutralization process, it can be subdivided into sodium carboxymethyl cellulose, lithium carboxymethyl cellulose and potassium carboxymethyl cellulose. The aqueous solution of carboxymethyl cellulose has the functions of thickening, film-forming, bonding and suspension. In recent years, with the rapid development of new energy, sodium carboxymethyl cellulose and lithium carboxymethyl cellulose have begun to be used as dispersants and binders for battery slurries in large quantities. For example, the mass production of sodium carboxymethyl cellulose and lithium carboxymethyl cellulose by the applicant has been continuously invested in the manufacturing and production of downstream power batteries, consumer batteries and energy storage batteries in recent years.

[0003] In addition to being used as a dispersant and binder in the battery manufacturing process, sodium carboxymethyl cellulose is also used as a soil water retainer because of its water-retaining properties. Compared with some polymer synthetic water retainers, such as hydrolyzed polyacrylonitrile, polyvinyl alcohol and polyacrylamide, sodium carboxymethyl cellulose has significant advantages in degradability and environmental friendliness. Sodium carboxymethyl cellulose can be decomposed by soil microorganisms, and the decomposition products are safe and harmless to the soil, and the glucose formed after decomposition can provide nutritious organic matter for soil microorganisms. However, the introduced sodium ions can easily cause land salinization and affect the normal growth of plants; in addition, the nature of traditional carboxymethyl cellulose that is too easily degraded by microorganisms also brings about the problem of short action time of water retainers and poor circulation performance.

[0004] Potassium carboxymethyl cellulose has the same main structure as sodium carboxymethyl cellulose and lithium carboxymethyl cellulose, but there are few studies on the use of potassium carboxymethyl cellulose as a water-retaining agent. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a water-retaining agent comprising potassium carboxymethyl cellulose, so as to solve the problems that sodium carboxymethyl cellulose used as a water-retaining agent is prone to cause land salinization and carboxymethyl cellulose is too easily degraded, resulting in a short action time and poor circulation performance of the water-retaining agent.

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

[0007] Application of potassium carboxymethyl cellulose. Potassium carboxymethyl cellulose is used as a soil water-retaining agent. The substitution degree of the potassium carboxymethyl cellulose is 0.6-2.2, and the substitution uniformity is 0.501-1.

[0008] Preferably, the neutralization degree of the potassium carboxymethyl cellulose is 0.4-0.8.

[0009] The present invention also provides a water retaining agent, which is suitable for soil water retention; the water retaining agent comprises potassium carboxymethyl cellulose, and the substitution degree of the potassium carboxymethyl cellulose is 0.6-2.2, and the substitution uniformity is 0.501-1.

[0010] Preferably, the degree of substitution of the potassium carboxymethyl cellulose is 0.8-2.2, and the uniformity of substitution is 0.747-1.

[0011] Preferably, the degree of substitution of the potassium carboxymethyl cellulose is 0.8-1.0, and the uniformity of substitution is 0.747-1.

[0012] Preferably, the neutralization degree of the potassium carboxymethyl cellulose is 0.4-0.8.

[0013] Preferably, the neutralization degree of the potassium carboxymethyl cellulose is 0.4-0.6.

[0014] Preferably, the water retaining agent further comprises benzoic acid, and the added amount of benzoic acid accounts for 0.1-1% of the total mass of potassium carboxymethyl cellulose calculated as a percentage by mass.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The present invention uses potassium carboxymethyl cellulose to replace sodium carboxymethyl cellulose as a soil water retaining agent. Potassium is an essential element for plant growth and can be absorbed by plants, avoiding the risk of sodium ions causing salinization of the soil. The present invention explores the influence of the degree of substitution and substitution uniformity of potassium carboxymethyl cellulose on its performance in the soil, and unexpectedly finds that potassium carboxymethyl cellulose in a specific degree of substitution range and substitution uniformity range has better anti-degradation ability, and has significantly higher and more lasting water retention capacity as a soil water retaining agent.

[0017] 2. The present invention also explores the effect of the neutralization degree of potassium carboxymethyl cellulose on its performance in the soil, and unexpectedly finds that the use of potassium carboxymethyl cellulose in a specific neutralization range can enable the water retaining agent to obtain adaptive functions for the pH value and salt content of the land under different conditions, and can better adjust the soil conditions to make it more suitable for plant growth.

[0018] 3. The present invention also uses potassium carboxymethyl cellulose and benzoic acid in combination. Benzoic acid itself can regulate the growth of plant roots, further enhancing the anti-degradation ability of potassium carboxymethyl cellulose. The unreacted carboxymethyl group in potassium carboxymethyl cellulose can also provide a sufficient acidic environment for benzoic acid to enhance the bactericidal ability of the water retaining agent. The combination of the two produces an effective synergistic effect. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments, but the embodiments of the present invention are not limited thereto.

[0020] The numerical ranges in the present invention are understood to also specifically disclose each intermediate value between the upper and lower limits of the range. Each smaller range between any intermediate value in the stated value or stated range and any other stated value or intermediate value in the stated range is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded in the range.

[0021] Unless otherwise specified, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art in the art to which the present invention relates. As used herein, "comprising", "including", "having", "containing", etc. are all open-ended terms, i.e., including but not limited to. The experimental methods used in the present invention are conventional methods unless otherwise specified. The materials, reagents, etc. used in the present invention, unless otherwise specified, can be purchased or synthesized by known methods.

[0022] The present invention will be further described below in conjunction with embodiments.

[0023] 1. A soil water retaining agent

[0024] In recent years, the applicant's mass-produced sodium carboxymethyl cellulose and lithium carboxymethyl cellulose have been continuously invested in the manufacturing and production of downstream power batteries, consumer batteries and energy storage batteries. At the same time, the applicant is also further expanding the research on the application of sodium carboxymethyl cellulose, lithium carboxymethyl cellulose and potassium carboxymethyl cellulose in other technical fields.

[0025] The water-retaining agent of the present invention comprises potassium carboxymethyl cellulose, and the substitution degree of the potassium carboxymethyl cellulose is 0.6-2.2, and the substitution uniformity of the potassium carboxymethyl cellulose is 0.501-1.

[0026] In some specific embodiments, the neutralization degree of the cellulose potassium is 0.4-0.8.

[0027] The structural formula of potassium carboxymethyl cellulose of the present invention is as follows:

[0028]

[0029] Wherein, R represents H or COOH or COOK, and n represents the number of repeating units (ie, degree of polymerization).

[0030] It should be noted that the specific meanings of the degree of substitution, substitution uniformity and neutralization degree described in the present invention are as follows:

[0031] Assume that the total number of H at the R substitution position in the molecular chain of potassium carboxymethyl cellulose is a, the total number of COOH is b, and the total number of COOK is c; the number of glucose units with all three R substitution positions being H (i.e., none of the hydroxyl groups on the glucose unit is replaced by a carboxymethyl group) is x, then:

[0032] (1)

[0033] (2)

[0034] (3)

[0035] It should be understood that carboxymethyl cellulose is a polymer material, and there are differences in the degree of polymerization between individual molecules. The parameters a, b, c, x, n, etc. are all overall average values ​​obtained by unit sample testing, rather than data of a single molecule. The degree of substitution of potassium carboxymethyl cellulose is a common indicator of carboxymethyl cellulose ethers. Those skilled in the art are aware of its test method, for example, it can be tested with reference to the national standard "GB 1886.232-2016". The degree of neutralization can be calculated by detecting the potassium content and combining the degree of substitution. The uniformity of substitution can be tested as follows: potassium carboxymethyl cellulose is placed in a strong acid aqueous solution with a pH value of 2 to 4, and it is thoroughly hydrolyzed into monosaccharides. Since there are significant differences between the glucose units that are not substituted by carboxymethyl and the glucose units that are substituted by carboxymethyl, the monosaccharides after hydrolysis can be separated by liquid chromatography to measure the content of the unsubstituted and substituted glucose units.

[0036] Potassium carboxymethyl cellulose is a compound modified from natural cellulose. Compared with synthetic polymer materials, it has better biodegradability and water retention capacity. Potassium is an element required for plant growth. The potassium ions in potassium carboxymethyl cellulose have weak ion exchange capacity and lose slowly, which can supplement trace amounts of potassium for plants over a long period of time.

[0037] In the present invention, it is unexpectedly found that the degree of substitution and the uniformity of substitution have a significant effect on the degradation rate of potassium carboxymethyl cellulose in soil. When the uniformity of substitution exceeds 0.5, the degradation rate of potassium carboxymethyl cellulose decreases significantly in the same time. The inventor speculates that the possible reason is that the degradation of potassium carboxymethyl cellulose is accompanied by the cleavage of the glycosidic bond on the molecular chain, and after the hydroxyl group on the glucose unit of cellulose is replaced by carboxymethyl, the glycosidic bond between two adjacent glucose units becomes less likely to break, thus showing better anti-degradation. When the substitution is uneven, even if the degree of substitution is high, there is still a situation where the hydroxyl groups on some adjacent glucose units are not replaced, and the glycosidic bond connecting the two glucose units is still easy to break, and the degradation rate cannot be reduced. When the degree of substitution is less than 0.6, the uniformity of substitution is difficult to achieve more than 0.5, and the degree of substitution of the potassium carboxymethyl cellulose can be further preferably 0.8 to 1.0. The degree of substitution after further optimization can provide the necessary conditions for the carboxylmethyl in potassium carboxymethyl cellulose to be more evenly distributed, and the anti-degradation ability of potassium carboxymethyl cellulose is better. However, although increasing the degree of substitution can continue to enhance its anti-degradation ability, it will cause its acidity value to gradually increase, so the degree of substitution should not be too large.

[0038] In the present invention, it is unexpectedly found that when the neutralization degree of carboxymethyl cellulose is in the range of 0.4 to 0.8, it can play an adaptive regulating role on the pH value and conductivity of the soil. The neutralization degree is the ratio of the number of corresponding carboxymethyl cellulose salts generated after the carboxymethyl cellulose is neutralized to all carboxymethyl groups. The inventor speculates that the possible reason is that the carboxymethyl cellulose potassium in this neutralization range has unneutralized carboxymethyl groups, which makes the carboxymethyl cellulose potassium acidic as a whole, which can better inhibit the activity of bacteria and extend the service life of carboxymethyl cellulose potassium. The remaining carboxymethyl groups of carboxymethyl cellulose potassium are weak acids, and only part of the acid is ionized; for acidic soils, the ionization of the remaining carboxymethyl cellulose of carboxymethyl cellulose potassium will be inhibited, making the pH value neutral, so that the conditions near the plant roots are more suitable for plant growth; for alkaline soils, the remaining carboxymethyl groups can be neutralized to alleviate the excessive alkalinity of the soil; for land with a high salt content, the remaining carboxymethyl groups can react with their salts to concentrate the salt around the plants to improve the soil environment.

[0039] In some embodiments, the water retaining agent also includes benzoic acid, and the amount of benzoic acid added is 0-1% of the total mass of potassium carboxymethylcellulose according to the mass percentage. Adding benzoic acid can further enhance the anti-degradation ability and gelation ability of potassium carboxymethylcellulose. Under the water absorption state, hydrogen bonds can be formed between benzoic acid and potassium carboxymethylcellulose to enhance the water retention capacity of potassium carboxymethylcellulose. At the same time, this hydrogen bonding effect can also reduce the loss of benzoic acid and prolong the bactericidal time of benzoic acid. At the same time, the unneutralized carboxymethyl group can also provide an acidic environment for benzoic acid, further enhancing the bactericidal ability of benzoic acid. In addition, benzoic acid also has a certain regulatory ability for plant root growth.

[0040] The method for preparing carboxymethyl cellulose can be any known method for producing carboxymethyl cellulose, for example, a water-based method can be used. The water-based method is specifically:

[0041] After alkalizing the cellulose to obtain alkalized cellulose, an acid is added to react with the alkalized cellulose to obtain carboxymethyl cellulose, and finally potassium hydroxide is added to neutralize the cellulose to obtain the potassium carboxymethyl cellulose, wherein the acid is chloroacetic acid.

[0042] 2. Description of performance testing methods

[0043] 1. Water retention test method:

[0044] Record the mass of deionized water added to the sample as m1, record the total mass of the sample after adding deionized water as m2, place the sample in an environmental chamber at 50°C and 60% RH for 24 hours, then take it out and weigh its mass as m3.

[0045] Water retention rate = 1-[(m2-m3) / m1×100%].

[0046] 2. Degradation rate detection method:

[0047] Preparation of potassium carboxymethyl cellulose tablets: Take a certain mass (denoted as a1) of potassium carboxymethyl cellulose powder in a tablet press, maintain the pressure at 10t for 10s, then release the pressure and take it out. Weigh 100g of soil and 25g of deionized water, mix them evenly and set aside. Take 80g of the prepared wet soil in a beaker, put the prepared potassium carboxymethyl cellulose tablet on the surface, and then cover it with 20g of the prepared wet soil. Put the sample in an environmental box at 30℃ and 60%RH and let it stand for 7d, then take out the carboxymethyl cellulose tablet, take out the carboxymethyl cellulose tablet, dry it and weigh it as a2.

[0048] Degradation rate = (a2) / a1×100%.

[0049] 3. pH value detection method:

[0050] The test was conducted in accordance with NY / T 1377-2007 “Determination of soil pH”.

[0051] 4. Conductivity detection method:

[0052] Weigh a certain mass of sample and put it into a glass container. Add a certain mass of deionized water and stir it gently with a glass rod for a few weeks. Let it stand for 24 hours and take the upper clear liquid to measure its value with a conductivity meter. The temperature during measurement is 25℃.

[0053] 5. Preparation method of prefabricated soil for experiment:

[0054] Soil from the surface to a depth of 20 cm was dug from a nearby farmland, and 5 points of the farmland were randomly selected. After removing particles and impurities visible to the naked eye, the obtained soil was mixed with a mixer and air-dried under natural conditions for later use.

[0055] 6. Source of potassium carboxymethyl cellulose:

[0056] The potassium carboxymethyl cellulose used in the embodiment of the present invention is produced by Dayingxing Juyao New Material Technology Co., Ltd., which is a wholly-owned subsidiary of the applicant and its main business is the production and manufacture of carboxymethyl cellulose materials. The viscosity range of the carboxymethyl cellulose used in the embodiment of the present invention is: at 25°C, using a Brookfield viscometer, the viscosity range of 1% solid content is above 500mPa.s.

[0057] 3. Specific Example Test and Results

[0058] The first experiment: To explore the effects of degree of substitution, uniformity of substitution and benzoic acid additive of potassium carboxymethyl cellulose on water retention and degradation rate.

[0059] Example 1

[0060] This embodiment uses potassium carboxymethyl cellulose with a substitution degree of 0.5, a neutralization degree of 0.4, and a substitution uniformity of 0.378 as a soil water retaining agent. 100.0 g of prefabricated soil and 5.0 g of the potassium carboxymethyl cellulose are weighed and mixed evenly, and 45.0 g of deionized water is slowly and evenly added to the surface of the obtained soil mixture. The water retention rate and degradation rate are tested according to the above method.

[0061] Example 2

[0062] The difference between this embodiment and embodiment 1 is that potassium carboxymethyl cellulose with a substitution degree of 0.6, a neutralization degree of 0.4, and a substitution uniformity of 0.456 is used.

[0063] Example 3

[0064] The difference between this embodiment and embodiment 1 is that potassium carboxymethyl cellulose with a substitution degree of 0.8, a neutralization degree of 0.4 and a substitution uniformity of 0.296 is used.

[0065] Example 4

[0066] The difference between this embodiment and embodiment 1 is that potassium carboxymethyl cellulose with a substitution degree of 0.8, a neutralization degree of 0.4 and a substitution uniformity of 0.501 is used.

[0067] Example 5

[0068] The difference between this embodiment and embodiment 1 is that potassium carboxymethyl cellulose with a substitution degree of 0.8, a neutralization degree of 0.4, and a substitution uniformity of 0.648 is used.

[0069] Example 6

[0070] The difference between this embodiment and embodiment 1 is that potassium carboxymethyl cellulose with a substitution degree of 1, a neutralization degree of 0.4, and a substitution uniformity of 0.887 is used.

[0071] Example 7

[0072] The difference between this embodiment and embodiment 1 is that potassium carboxymethyl cellulose with a substitution degree of 1, a neutralization degree of 0.4, and a substitution uniformity of 0.887 is used.

[0073] Example 8

[0074] The difference between this embodiment and embodiment 1 is that potassium carboxymethyl cellulose with a substitution degree of 1.5, a neutralization degree of 0.4, and a substitution uniformity of 0.932 is used.

[0075] Example 9

[0076] The difference between this embodiment and embodiment 1 is that potassium carboxymethyl cellulose with a substitution degree of 2.2, a neutralization degree of 0.4, and a substitution uniformity of 0.976 is used.

[0077] Example 10

[0078] The difference between this embodiment and embodiment 6 is that benzoic acid is further added, and the amount of benzoic acid added is 0.1% of the mass of potassium carboxymethyl cellulose.

[0079] Embodiment 11

[0080] The difference between this embodiment and embodiment 6 is that benzoic acid is further added, and the amount of benzoic acid added is 0.5% of the mass of potassium carboxymethyl cellulose.

[0081] Example 12

[0082] The difference between this embodiment and embodiment 6 is that benzoic acid is further added, and the amount of benzoic acid added is 1% of the mass of potassium carboxymethyl cellulose.

[0083] Embodiment 13

[0084] The difference between this embodiment and embodiment 6 is that benzoic acid is further added, and the amount of benzoic acid added is 2% of the mass of potassium carboxymethyl cellulose.

[0085] Blank example 1

[0086] The difference between this blank example and Example 1 is that 100.0 g of prefabricated soil was weighed, 45.0 g of deionized water was slowly and evenly added to the surface of the obtained soil mixture, and potassium carboxymethyl cellulose and benzoic acid were not added.

[0087] The main control conditions and test results of the first group of experiments are shown in Table 1.

[0088] Table 1 The first set of experimental test results

[0089]

[0090]

[0091] Data analysis of Table 1:

[0092] (1) Analysis of the influence of water retention performance:

[0093] In Blank Example 1, potassium carboxymethyl cellulose was not added, and the water retention rate was only 35.11%. After adding potassium carboxymethyl cellulose, the maximum water retention rate could reach 79.89%. It can be seen that the addition of potassium carboxymethyl cellulose significantly improved the water retention rate of the soil.

[0094] By comparing Examples 1 to 3 and Examples 7 to 9, it can be seen that: as the degree of substitution increases from 0.5 to 0.8, the water retention rate significantly increases by 7 percentage points; however, by comparing Example 6 and Example 9, as the degree of substitution increases from 0.8 to 2.2, the water retention rate increases by less than 3 percentage points. When the degree of substitution reaches 1, the water retention rate basically no longer increases with the increase in the degree of substitution. This result is unexpected to those skilled in the art.

[0095] Comparison of Examples 3 to 6 shows that, at the same degree of substitution, the uniformity of substitution of potassium carboxymethyl cellulose has little effect on the water retention rate of carboxymethyl cellulose, which is unexpected to those skilled in the art.

[0096] (2) Analysis of the influence of degradation rate performance: It can be seen from the comparison of Examples 3 to 6 that the substitution uniformity of potassium carboxymethyl cellulose has a great influence on its anti-degradability. It can be seen that when the substitution uniformity is lower than 0.5, the degradation rate decreases rapidly with the increase of the substitution degree. When the substitution degree is about 0.5, the degradation rate can be reduced to less than 30%. Comparing Examples 6 to 9, when the substitution uniformity is greater than 0.6, the degradation rate slowly decreases with the increase of the substitution degree. After the substitution uniformity exceeds 0.8, the degradation rate of potassium carboxymethyl cellulose remains basically unchanged and is not affected by the degree of substitution. It is speculated that the reason may be that the carboxylmethyl groups on the glucose units of carboxymethyl cellulose are more evenly distributed, the value difference of the substitution uniformity is small, and the overall structural stability remains basically unchanged with the increase of the substitution degree, so the anti-degradability does not change much; when the substitution degree is greater than 1.0, the anti-degradability remains basically unchanged.

[0097] (3) Effect of adding benzoic acid on soil water retention and degradation performance of potassium carboxymethyl cellulose: From the comparison of Examples 10 to 13, it can be seen that the addition of benzoic acid helps to improve the anti-degradation property of potassium carboxymethyl cellulose. When the dosage exceeds 1% of the mass of potassium carboxymethyl cellulose, the anti-degradation effect of potassium carboxymethyl cellulose is not significantly improved.

[0098] The second experiment: explore the effect of the neutralization degree of carboxymethyl cellulose potassium on soil pH and conductivity.

[0099] Blank example 2

[0100] Blank Example 2 Set up four test groups A, B, C, and D, numbered Blank 2-A, Blank 2-B, Blank 2-C, and Blank 2-D, respectively.

[0101] The composition of the test substance of space 2-A is: a mixture of 100.0 g of prefabricated soil and 45.0 g of deionized water;

[0102] The test substance composition of space 2-B is: a mixture of 100.0 g of prefabricated soil and 45.0 g of 1 mmol / L sodium chloride aqueous solution;

[0103] The composition of the test substance of the empty 2-C is: a mixture of 100.0 g of prefabricated soil and 45.0 g of hydrochloric acid aqueous solution with a pH of 5.8;

[0104] The composition of the test substance of the empty 2-D is a mixture of 100.0 g of prefabricated soil and 45.0 g of a sodium hydroxide aqueous solution with a pH of 8.

[0105] Embodiment 14

[0106] The difference between Example 14 and Blank Example 2 is that 5.0 g of potassium carboxymethyl cellulose is added to the test substances in the four groups A, B, C, and D of Blank Example 2, and the neutralization degree of the potassium carboxymethyl cellulose used is 0.2, the substitution degree is 0.8, and the substitution uniformity is 0.649.

[0107] Embodiment 15

[0108] The difference between Example 15 and Example 14 is that the neutralization degree of the potassium carboxymethyl cellulose used is 0.4, the substitution degree is 0.8, and the substitution uniformity is 0.649.

[0109] Example 16

[0110] The difference between Example 16 and Example 14 is that the neutralization degree of the potassium carboxymethyl cellulose used is 0.6, the substitution degree is 0.8, and the substitution uniformity is 0.649.

[0111] Embodiment 17

[0112] The difference between Example 17 and Example 14 is that the neutralization degree of the potassium carboxymethyl cellulose used is 0.8, the substitution degree is 0.8, and the substitution uniformity is 0.649.

[0113] Embodiment 18

[0114] The difference between Example 18 and Example 14 is that the neutralization degree of the potassium carboxymethyl cellulose used is 1, the substitution degree is 0.8, and the substitution uniformity is 0.649.

[0115] Embodiment 19

[0116] The difference between Example 19 and Example 14 is that the neutralization degree of the potassium carboxymethyl cellulose used is 0.4, the substitution degree is 0.6, and the substitution uniformity is 0.456.

[0117] Embodiment 20

[0118] The difference between Example 20 and Example 14 is that the neutralization degree of the potassium carboxymethyl cellulose used is 0.8, the substitution degree is 2.2, and the substitution uniformity is 0.976.

[0119] The pH value and conductivity of Group A in Blank Example 2 and Examples 14 to 20 were tested;

[0120] The conductivity of group B in blank example 2 and examples 14 to 20 was tested;

[0121] The pH value of group C in blank example 2 and examples 14 to 20 was tested;

[0122] The pH value of Group D in Blank Example 2 and Examples 14 to 20 was tested.

[0123] The main control conditions and test results of the second experiment are shown in Table 2.

[0124] Table 2

[0125]

[0126] Data analysis of Table 2:

[0127] (1) Comparing the data of Group A of Blank Example 2 and Examples 14 to 20, it can be seen that after adjusting the price of potassium carboxymethyl cellulose in the soil, except for the data of Example 18-A which has a slightly obvious change compared with the blank example (the conductivity increased by 0.06 and the pH value increased by 0.08), the pH and conductivity of the soil of other examples have negligible fluctuations compared with Blank Example 2. It can be considered that the use of potassium carboxymethyl cellulose does not cause significant changes in the pH value and salt content of the soil close to neutral.

[0128] (2) Comparing the data of group B of blank example 2 and examples 14 to 20, it can be seen that when the neutralization degree of potassium carboxymethyl cellulose is between 0.2 and 0.8, the conductivity is reduced compared with that in blank 2-B group after adding potassium carboxymethyl cellulose, but the conductivity is slightly improved in comparison of the experiments of groups A and B in each example; when the neutralization degree exceeds 0.8 and reaches 1, it will cause the conductivity of the soil to rise slightly. It can be considered that when the neutralization degree is between 0.2 and 0.8, the addition of potassium carboxymethyl cellulose can adaptively adjust the alkali metal ion content of the soil within a certain range, which can alleviate the soil with high salinization degree.

[0129] (3) Comparing the data of Group C of Blank Example 2 and Examples 14 to 20, it can be seen that the addition of potassium carboxymethyl cellulose with a neutralization degree of 0.4 to 0.8 can increase the pH and maintain it close to the pH value measured in Group A. However, when the neutralization degree of potassium carboxymethyl cellulose added is 0.2, it no longer has the effect of raising the pH in an acidic solution system with a pH of 5.8.

[0130] (4) Comparing the data of group D of blank example 2 and examples 14 to 20, it can be seen that the addition of potassium carboxymethyl cellulose with a neutralization degree of 0.2 to 0.8 can lower the pH and maintain it close to the pH value measured in each group A. However, when the neutralization degree of potassium carboxymethyl cellulose added is 1, in an alkaline solution system with a pH of 8, it does not have the effect of lowering the pH, but instead slightly increases the soil pH.

[0131] From the comprehensive analysis of Table 2, it can be seen that when the neutralization degree of the added potassium carboxymethyl cellulose is in the range of 0.4 to 0.8, the pH value and alkali metal ion content of the soil can be automatically adjusted within a certain range, and the preferred neutralization degree is 0.4 to 0.6.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. The application of potassium carboxymethyl cellulose is characterized in that: Potassium carboxymethyl cellulose is used as a soil water-retaining agent. The substitution degree of the potassium carboxymethyl cellulose is 0.6-2.2, and the substitution uniformity is 0.501-1.

2. The use according to claim 1, characterized in that: The neutralization degree of the potassium carboxymethyl cellulose is 0.4-0.

8.

3. A water-retaining agent, characterized in that: The water retaining agent is suitable for soil water retention; the water retaining agent comprises potassium carboxymethyl cellulose, and the substitution degree of the potassium carboxymethyl cellulose is 0.6-2.2, and the substitution uniformity is 0.501-1.

4. The water-retaining agent according to claim 3, characterized in that The substitution degree of the potassium carboxymethyl cellulose is 0.8-2.2, and the substitution uniformity is 0.747-1.

5. The water-retaining agent according to claim 3, characterized in that The substitution degree of the potassium carboxymethyl cellulose is 0.8-1.0, and the substitution uniformity is 0.747-1.

6. The water-retaining agent according to any one of claims 3 to 4, characterized in that The neutralization degree of the potassium carboxymethyl cellulose is 0.4-0.

8.

7. The water-retaining agent according to claim 6, characterized in that The neutralization degree of the potassium carboxymethyl cellulose is 0.4-0.

6.

8. The water-retaining agent according to any one of claims 3 to 7, characterized in that The water retaining agent also includes benzoic acid. Calculated by mass percentage, the added amount of benzoic acid accounts for 0.1-1% of the total mass of potassium carboxymethyl cellulose.

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