A salt-alkali-resistant and salt-isolating material for seedlings based on modified activated carbon fiber, and its preparation method and application

Abstract

The present invention provides a salt-alkali resistant salt-isolating material for seedlings based on modified activated carbon fiber, and its preparation method and application. The preparation method comprises the following steps: first, stirring and pre-treating the activated carbon fiber with an acid-modified solution and an alkali-modified solution respectively; after the reaction is completed, washing the activated carbon fiber with deionized water until the pH of the washing solution is neutral; vacuum drying for standby use; adding a strong oxidant to the pretreated activated carbon fiber until the activated carbon fiber is completely immersed in the reaction solution; magnetic stirring for reaction; after the reaction is completed, washing the activated carbon fiber with deionized water until the pH of the washing solution is neutral; vacuum drying to obtain a salt-isolating material; the salt-isolating material is applied in saline-alkali soil or saltwater irrigation environment to improve the salt tolerance of seedlings. The salt-isolating material of the present invention has a simple preparation process, mild reaction conditions, is easy to control, and has stable product quality, is suitable for large-scale production, and has high application feasibility.

Description

Technical Field

[0001] The invention belongs to the technical field of modified materials and their application in plant cultivation, and particularly relates to a seedling salt-resistant and alkali-isolating material based on modified activated carbon fiber, a preparation method and an application thereof. Background Art

[0002] Saline-alkali soils are widely distributed around the world, especially in arid and semi-arid areas. The accumulation of salt poses a serious threat to the ecological environment and agricultural production. High salinity can inhibit plant growth and significantly reduce the survival rate of greening seedlings and crops. In addition, in the context of water scarcity, although brackish water has a certain reserve, due to its high salt content, direct use for irrigation often further aggravates soil salinization and threatens the survival of tree seedlings. Therefore, the rational use of brackish water resources and the reduction of the harm of salt to plants have become key issues that need to be addressed. In order to meet this challenge, it is urgent to develop an efficient salt isolation technology to reduce the impact of salt in soil or irrigation water on plant roots, thereby improving the survival rate and salt resistance of seedlings.

[0003] Currently, commonly used salt-isolating materials include physical barrier materials such as geotextiles and polymer membranes, as well as some chemical modifiers. These materials can slow the movement of salt to a certain extent, but they often have problems such as poor durability, high cost, and insufficient environmental friendliness. In addition, the salt-isolating effect gradually weakens under high salt concentrations or long-term use. Therefore, to address these problems, finding a new, efficient and sustainable salt-isolating material has become a key technical means to improve the survival rate of seedlings in saline-alkali land. Activated carbon fiber, due to its excellent adsorption properties, high specific surface area, and structural adjustability, shows great potential as a salt-isolating material in saline-alkali land.

[0004] As a porous material, activated carbon fiber has good adsorption properties and can effectively adsorb salt in soil or irrigation water, preventing the migration of salt to the roots of plants. However, unmodified activated carbon fiber has certain disadvantages, such as the limited number of functional groups on its surface and less than ideal adsorption capacity, making it difficult to achieve the best salt isolation effect in harsh saline-alkali environments. Therefore, pre-treatment and oxidative modification of activated carbon fiber to increase the oxygen-containing functional groups (such as carboxyl and hydroxyl groups) on its surface can significantly improve its adsorption capacity and hydrophilicity, and enhance its salt isolation performance. This modified activated carbon fiber material can not only effectively prevent the migration of salt, but also retain water, maintain a suitable moisture environment around the roots, and further improve the survival ability of plants in saline-alkali land.

[0005] Based on this, a salt-resistant and alkali-resistant salt-isolating material for seedlings based on modified activated carbon fibers was proposed. By subjecting the activated carbon fibers to acid-base pretreatment and oxidation modification, the content of oxygen-containing functional groups on their surface was increased, effectively enhancing their performance as a salt-isolating material. Under saline-alkali soil and brackish water irrigation conditions, this material can prevent salt from penetrating plant roots, reducing damage to seedlings caused by salt and alkali, and significantly improving their survival rate. This provides an efficient and sustainable solution for ecological restoration and greening of saline-alkali land. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a salt-alkali-resistant and salt-isolating material for seedlings based on modified activated carbon fiber and its application in order to solve the problems raised in the above-mentioned background technology.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] In a first aspect, a method for preparing a salt-alkali-resistant and salt-isolating material for seedlings based on modified activated carbon fiber comprises the following steps:

[0009] S1. Pre-treating the activated carbon fiber with an acid-modified solution by stirring. After the reaction is completed, the activated carbon fiber is washed with deionized water until the pH of the washing solution is neutral. After vacuum drying, the activated carbon fiber is pre-treated with an alkali-modified solution by stirring. After the reaction is completed, the activated carbon fiber is washed with deionized water until the pH of the washing solution is neutral. After vacuum drying, the activated carbon fiber is set aside.

[0010] S2. Add a strong oxidant to the pretreated activated carbon fiber in S1 until the activated carbon fiber is completely immersed in the reaction solution, and stir the reaction magnetically. After the reaction is completed, wash the activated carbon fiber with deionized water until the pH of the washing solution is neutral, and vacuum dry to obtain a salt-isolating material.

[0011] As a further illustration of the present invention, the acid-modified solution is hydrochloric acid with a mass fraction of 3.00-15.00%, and the base-modified solution is hydrochloric acid with a molar concentration of 0.20-1.00 mol·L -1 The volume ratio of the activated carbon fiber mass to the acid-modified solution or the alkali-modified solution is 50.00-100.00 g·L -1 .

[0012] As a further illustration of the present invention, the strong oxidant has a concentration of 2.00-6.00 mol·L -1 Nitric acid, concentration is 8.00-10.00 mol·L -1 of hydrogen peroxide or a concentration of 0.02-0.06 mol·L -1The volume ratio of the pretreated activated carbon fiber to the strong oxidant is 200.00-400.00 g·L -1 .

[0013] As a further illustration of the present invention, the stirring speed of the acid-modified solution or the alkaline-modified solution in S1 is 180-220 rpm, the stirring time is 1-3 h, the stirring temperature of the acid-modified solution is 20-35 ° C, the stirring temperature of the alkaline-modified solution is 50-65 ° C, the vacuum drying temperature is 60-100 ° C, and the vacuum drying time is 8-12 h.

[0014] As a further illustration of the present invention, the magnetic stirring speed in S2 is 180-220 rpm, and the stirring time is 2-6 h; the magnetic stirring temperature is 60-80° C., the vacuum drying temperature is 80-100° C., and the vacuum drying time is 12-18 h.

[0015] In a second aspect, a salt-alkali resistant and salt-isolating material for seedlings based on modified activated carbon fiber is prepared by the above-mentioned method for preparing the salt-isolating material.

[0016] Thirdly, a salt-resistant and salt-isolating material for seedlings based on modified activated carbon fiber is used to improve the salt tolerance of seedlings in saline-alkali soil or salt water irrigation environment.

[0017] As a further illustration of the present invention, the salt content of the saline-alkali soil is 0.10%-0.80%, the salt content of the saline water irrigation is 0.10%-1.50%, and the salt-isolating material wraps 2-5 mm around the roots of the seedlings.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The preparation process of the salt barrier material in the present invention is simple, the reaction conditions are mild, easy to control, and the product quality is stable, suitable for large-scale production, and has high application feasibility.

[0020] 2. This invention significantly increases the content of surface oxygen-containing functional groups, such as carboxyl and hydroxyl groups, by subjecting activated carbon fibers to acid-base pretreatment and oxidative modification. Boehm titration shows that the surface oxygen-containing functional group content of the modified activated carbon fibers increases to 250% to 350% of the pre-modification level. This modification enhances the material's ability to absorb and block salt, effectively mitigating the damage caused by salt to the roots of saplings, thereby significantly improving their survival rate in saline-alkali soils.

[0021] 3. The salt-isolating material of the present invention is environmentally friendly, low in toxicity, and economical and convenient to use. In saline-alkali soil or saltwater irrigation environment, it can not only block salt but also reduce water consumption. It is suitable for greening and ecological restoration in water-scarce areas.

[0022] 4. The present invention constructs an efficient "physical barrier-chemical adsorption" double salt barrier by directly applying modified activated carbon fiber materials to the roots of seedlings, which greatly improves the salt isolation effect, reduces the shortcomings of traditional salt isolation technology, and provides an efficient and sustainable solution for the cultivation of seedlings in saline-alkali land.

[0023] 5. The material of the present invention can flexibly adjust the wrapping thickness according to different salinity conditions, adapt to a variety of complex environments, further improve the survival ability of seedlings in high-salt environments, and provide new technical ideas for the restoration of saline-alkali land ecosystems and agricultural development. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a growth comparison chart of Ulmus pumila in Example 1 with and without the use of salt isolation material.

[0025] Figure 2 This is a comparison of the plant heights of Ulmus pumila in Example 1 with and without the use of salt-isolating materials.

[0026] Figure 3 This is a growth comparison diagram of water wax in Example 2 with and without the use of salt isolation material.

[0027] Figure 4 This is a comparison chart of the soil electrical conductivity values ​​inside and outside the isolation layer of water wax using salt isolation material in Example 2.

[0028] Figure 5 This is a growth comparison chart of Forsythia suspensa in Example 3 with and without the use of salt isolation material.

[0029] Figure 6 This is a comparison chart of the salt content of the soil inside and outside the isolation layer of Forsythia suspensa when using salt isolation material in Example 3. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] The present invention provides a technical solution: a method for preparing a salt-alkali-resistant and salt-isolating material for seedlings based on modified activated carbon fiber, comprising the following steps:

[0032] S1. Pre-treating the activated carbon fiber with an acid-modified solution by stirring. After the reaction is completed, the activated carbon fiber is washed with deionized water until the pH of the washing solution is neutral. After vacuum drying, the activated carbon fiber is pre-treated with an alkali-modified solution by stirring. After the reaction is completed, the activated carbon fiber is washed with deionized water until the pH of the washing solution is neutral. After vacuum drying, the activated carbon fiber is set aside.

[0033] The acid-modified solution is hydrochloric acid with a mass fraction of 3.00-15.00%, and the base-modified solution is hydrochloric acid with a molar concentration of 0.20-1.00 mol·L -1 The volume ratio of the activated carbon fiber mass to the acid-modified solution or the alkali-modified solution is 50.00-100.00 g·L -1 ;

[0034] The stirring speed of acid-modified solution or alkaline-modified solution treatment is 180-220rpm, the stirring time is 1-3h, the stirring temperature of acid-modified solution treatment is 20-35℃, the stirring temperature of alkaline-modified solution treatment is 50-65℃, the vacuum drying temperature is 60-100℃, and the vacuum drying time is 8-12h

[0035] S2. Add a strong oxidant to the activated carbon fiber pretreated in S1, wherein the concentration of the strong oxidant is 2.00-6.00 mol·L -1 Nitric acid, concentration is 8.00-10.00 mol·L -1 of hydrogen peroxide or a concentration of 0.02-0.06 mol·L -1 The volume ratio of the pretreated activated carbon fiber to the strong oxidant is 200.00-400.00 g·L -1 , until the activated carbon fiber is completely immersed in the reaction solution, magnetic stirring reaction, the magnetic stirring speed is 180-220rpm, the stirring time is 2-6h; the magnetic stirring temperature is 60-80℃, after the reaction is completed, use deionized water to wash the activated carbon fiber until the pH of the washing liquid is neutral, and vacuum drying to obtain the salt isolation material, the vacuum drying temperature is 80-100℃, and the vacuum drying time is 12-18h.

[0036] Example 1: Using a 10% hydrochloric acid solution as the acid modification solution, the volume ratio of the activated carbon fiber mass to the hydrochloric acid solution is 75 g·L -1 , stirred at 200 rpm for 2 h at 25 °C, and then washed with a large amount of deionized water until the pH of the washing solution was close to neutral;

[0037] The concentration of the re-use is 0.50 mol·L -1 The sodium hydroxide solution was used as the alkali modification solution, and the volume ratio of the activated carbon fiber mass to the sodium hydroxide solution was 75 g·L -1, stirred at 60 °C for 2 h, then washed with deionized water until neutral, and vacuum dried at 80 °C for 10 h;

[0038] The pretreated activated carbon fiber was added with 3 mol·L -1 In the nitric acid solution, the volume ratio of activated carbon fiber to nitric acid solution is 300g·L -1 , stirred at 200 rpm at 70 ° C for 4 hours. After the reaction is completed, it is washed with deionized water to neutrality and vacuum dried at 90 ° C for 15 hours to obtain a modified activated carbon fiber salt isolation material.

[0039] The surface carboxyl content of the modified activated carbon fiber increased to 350% of that before modification, as measured by Boehm titration.

[0040] Conduct application and comparative experiments:

[0041] like Figure 1 and Figure 2 As shown in the study, the modified activated carbon fiber material was wrapped around the roots of one-year-old yellow elm seedlings, forming a 3 mm thick salt barrier. Twenty parallel groups were set up. In saline-alkali soil with a salt concentration of 0.60%, the transplanted yellow elms grew well over the 120-day planting period. During the experiment, the salt did not cause significant damage to their roots. The leaves of the seedlings maintained normal growth, and their roots were healthy, with a survival rate of 95%.

[0042] As a comparative experiment, a control group without salt-isolating materials was set up, which also consisted of 20 groups of yellow elm seedlings. Under the same saline-alkali soil conditions, the salt concentration was 0.60%;

[0043] The seedlings grown without the salt barrier experienced significant salt stress over the 120 days. Salt gradually accumulated in the roots, causing root rot, leaf wilting, and stunted growth, ultimately resulting in a survival rate of only 35%.

[0044] Example 2: Activated carbon fibers were modified according to the following steps. A 5% hydrochloric acid solution was used as the acid modification solution. The volume ratio of the activated carbon fibers to the hydrochloric acid solution was 60 g·L. -1 , stirred at 200 rpm at 30 ° C for 1.50 hours. After the reaction, wash with plenty of deionized water until neutral;

[0045] The concentration used is 0.75 mol·L -1 The sodium hydroxide solution was used as the alkali modification solution, and the volume ratio of the activated carbon fiber mass to the sodium hydroxide solution was 60 g·L -1 , stirred at 55 °C for 3 h, subsequently washed with deionized water until neutral, and dried in vacuo at 90 °C for 10 h.

[0046] The pretreated activated carbon fiber was added with 9 mol·L -1 In the hydrogen peroxide solution, the volume ratio of activated carbon fiber to hydrogen peroxide solution is 250g·L -1 , stirred at 200 rpm at 65 ° C for 5 hours. After the reaction is completed, it is washed with deionized water until neutral, and vacuum dried at 80 ° C for 12 hours to obtain a modified activated carbon fiber salt isolation material.

[0047] The surface hydroxyl content of the modified activated carbon fiber increased to 280% of that before modification, as measured by Boehm titration.

[0048] Conduct application and comparative experiments:

[0049] like Figure 3 and Figure 4 As shown, the prepared modified activated carbon fiber material was wrapped around the roots of the annual water wax to form a salt isolation layer with a thickness of 4 mm, and 20 parallel groups were set up.

[0050] Under saline irrigation conditions with a salt concentration of 1.20%, the transplanted wax palm demonstrated high salt tolerance over a 120-day planting period. During the experiment, the salt did not significantly affect its root system, maintaining normal leaf growth and healthy root systems, with a survival rate of 85%.

[0051] In a comparative experiment, 20 control groups of waxwood seedlings were also set up without salt-barrier materials. Under the same saline irrigation conditions, with a salt concentration of 1.20%, the untreated seedlings suffered significant root damage from gradual salt accumulation over a 120-day planting period. Their leaves withered, their growth was stunted, and their ultimate survival rate was only 25%.

[0052] Example 3: Modification of activated carbon fiber according to the following steps:

[0053] A 15% mass fraction hydrochloric acid solution was used as the acid modification solution, and the volume ratio of the activated carbon fiber mass to the hydrochloric acid solution was 90 g·L -1 , stirred at 220 rpm for 3 hours at 20°C. After the reaction, the mixture was washed with a large amount of deionized water until neutral.

[0054] The concentration used is 1.00 mol·L -1 The sodium hydroxide solution was used as the alkali modification solution, and the volume ratio of the activated carbon fiber mass to the sodium hydroxide solution was 80 g·L -1 , stirred at 65 ° C for 3 hours. After the reaction is completed, it is washed with deionized water to neutrality and dried in vacuum at 100 ° C for 8 hours.

[0055] The pretreated activated carbon fiber was added with 0.04 mol·L -1The volume ratio of activated carbon fiber to potassium permanganate solution is 350 g·L -1 , stirred at 220 rpm at 75 ° C for 3 hours. After the reaction is completed, it is washed with deionized water to neutrality and vacuum dried at 85 ° C for 12 hours to obtain a modified activated carbon fiber salt isolation material.

[0056] The surface carboxyl content of the modified activated carbon fiber increased to 300% of that before modification, as measured by Boehm titration.

[0057] Conduct application and comparative experiments:

[0058] like Figure 5 and Figure 6 As shown in the study, the modified activated carbon fiber material was wrapped around the roots of one-year-old forsythia suspensa plants, forming a 5-mm-thick salt barrier. Twenty parallel groups were set up. In saline-alkali soil with a salt concentration of 0.80%, the transplanted forsythia suspensa plants showed good growth over the 120-day planting period. During the experiment, the salt tolerance of the seedlings was significantly enhanced, their roots were not damaged by salt, and the seedlings grew well, with a survival rate of 80%.

[0059] In a comparative experiment, 20 groups of Forsythia suspensa seedlings were also planted without salt-isolating materials. Under the same saline-alkali soil conditions with a salt concentration of 0.80%, the seedlings without salt-isolating materials experienced root damage due to gradual salt accumulation over a 120-day planting period, stunting their growth and causing leaf withering. Ultimately, the survival rate was only 10%.

[0060] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0061] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a salt-alkali-resistant and salt-isolating material for seedlings based on modified activated carbon fiber, characterized in that: The following steps are involved: S1. The activated carbon fiber is first subjected to a stirring pretreatment reaction with an acid-modified solution. After the reaction is completed, the activated carbon fiber is washed with deionized water until the pH of the washing solution is neutral. After vacuum drying, the activated carbon fiber is then subjected to a stirring pretreatment reaction with an alkali-modified solution. After the reaction is completed, the activated carbon fiber is washed with deionized water until the pH of the washing solution is neutral. The activated carbon fiber is vacuum dried for standby use. The acid-modified solution is hydrochloric acid with a mass fraction of 3.00-15.00%, and the alkali-modified solution is hydrochloric acid with a molar concentration of 0.20-1.00 mol·L -1 The volume ratio of the activated carbon fiber mass to the acid-modified solution or the alkali-modified solution is 50.00-100.00 g·L -1 ; S2. Add a strong oxidant to the pretreated activated carbon fiber in S1 until the activated carbon fiber is completely immersed in the reaction solution, and stir the reaction magnetically. After the reaction is completed, wash the activated carbon fiber with deionized water until the pH of the washing solution is neutral, and vacuum dry to obtain a salt isolation material. The strong oxidant has a concentration of 2.00-6.00 mol·L -1 Nitric acid, concentration is 8.00-10.00 mol·L -1 of hydrogen peroxide or a concentration of 0.02-0.06 mol·L -1 The volume ratio of the pretreated activated carbon fiber to the strong oxidant is 200.00-400.00 g·L -1 .

2. The method for preparing a salt-alkali-resistant and salt-isolating material for seedlings based on modified activated carbon fiber according to claim 1, characterized in that: The acid-modified solution or alkaline-modified solution in S1 is stirred at a speed of 180-220 rpm for 1-3 h. The stirring temperature for the acid-modified solution is 20-35° C., and the stirring temperature for the alkaline-modified solution is 50-65° C. The vacuum drying temperature is 60-100° C., and the vacuum drying time is 8-12 h.

3. The method for preparing a salt-alkali-resistant and salt-isolating material for seedlings based on modified activated carbon fiber according to claim 1, characterized in that: In S2, the magnetic stirring speed is 180-220 rpm, and the stirring time is 2-6 h; the magnetic stirring temperature is 60-80° C., the vacuum drying temperature is 80-100° C., and the vacuum drying time is 12-18 h.

4. A salt-alkali-resistant and salt-isolating material for seedlings based on modified activated carbon fiber, characterized in that: The salt barrier material is prepared by the preparation method of any one of claims 1 to 3.

5. Use of the modified activated carbon fiber-based salt-resistant and salt-isolating material for seedlings according to claim 4 in planting seedlings in saline-alkali soil or salt water irrigation environment.

6. The use according to claim 5, characterized in that The salt content of the saline-alkali soil is 0.10%-0.80%, the salt content of the saline water irrigation is 0.10%-1.50%, and the salt-isolating material wraps the roots of the seedlings by 2-5 mm.

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