Super-hydrophobic sand-based composite material and preparation method thereof

Abstract

The super-hydrophobic sand-based composite material is prepared from sand, charcoal, zinc oxide and organic acid, the water contact angle of the composite material in air is larger than 150 degrees, the rolling angle of the composite material is smaller than 10 degrees, and after the composite material is circularly treated for 20 times at-80 DEG C and 110 DEG C, the water contact angle of the composite material is still larger than 150 degrees, and the rolling angle of the composite material is still smaller than 10 degrees; after soil is covered with the super-hydrophobic sand-based composite material, the evaporation rate of soil moisture can be reduced by 50-95%. The invention also discloses a preparation method of the composition. The composite material disclosed by the invention is good in water retention performance, not only can be stably used in extremely low-temperature and high-temperature regions, but also cannot cause harm to the environment and solve the problems of secondary plastic pollution and the like after being used, and meanwhile, the preparation process is simple, the energy consumption is low, the consumed time is short, the preparation cost is low, and large-scale production can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of soil water-retaining functional materials and preparation thereof, and specifically relates to a super-hydrophobic sand-based composite material and a preparation method thereof. Background Art

[0002] With global warming and intensified human activities, the evaporation rate of water vapor in the soil and the rate of soil erosion are accelerating, resulting in an increasing degree of soil desertification.

[0003] The existing effective way to solve soil desertification or sandification is to plant plants. When the plant roots fix the soil, the microbial system can be promoted to recover, thereby achieving the purpose of sand control and soil conservation. However, due to the increasing environmental temperature and human activities, the water-deficient desertified soil has lost its water retention capacity and cannot meet the water supply required for plant growth. Therefore, it is urgent to find a method that can meet plant growth, especially not hinder the growth of plant roots, and maintain moisture in the soil. Although the use of ground film can effectively reduce soil moisture evaporation, the use of ground film will bring two hazards: one is to inhibit the growth of plants such as grass; the other is that if it is not effectively recycled after use, the ground film will remain in the soil and bring about plastic pollution problems. Although the use of soil conditioners such as polyacrylamide can enhance the adhesion between soils and improve the physical properties of soils, so that the soil forms a more favorable water retention structure and reduces water increase, these conditioners will hinder the balance of microorganisms, that is, while inhibiting the growth of beneficial microorganisms, they will also promote the growth of harmful microorganisms, thereby causing the ecological function of the soil to be damaged and plants cannot grow healthily. In addition, although the use of super-absorbent or gel materials can also promote water retention in the soil, there are still problems of disrupting the balance of microorganisms and secondary plastic pollution, and super-absorbent materials can also hinder plant growth. Therefore, it is particularly necessary to find a new material that can achieve soil water retention without affecting the normal growth or reproduction of plants and microorganisms.

[0004] Superhydrophobic materials are new functional materials that are prepared by being inspired by the lotus leaf's "superhydrophobicity on the surface of the lotus leaf" and are defined as having a water contact angle greater than 150° and a rolling angle less than 10°. This type of material can effectively prevent water droplets from piercing and reduce water evaporation. In research, it was found that using sand to prepare this superhydrophobic material for soil water retention and normal plant growth has become one of the ideal solutions to the above problems. Moreover, using sand to prepare superhydrophobic materials can also improve the resource utilization rate of desertified soil itself. For example, Gallo et al. [GALLO A, ODOKONYERO K, MOUSA MAA, et al. Nature-Inspired Superhydrophobic Sand Mulches Increase Agricultural Productivity and Water-Use Efficiency in Arid Regions [J]. ACS Agricultural Science & Technology, 2022, 2 (2): 276-88] dissolved solid paraffin in n-hexane to modify sand to prepare superhydrophobic sand, and covered it on the soil surface to reduce water evaporation. The results of this study show that, on the one hand, after covering the soil with a thickness of 5 to 10 mm of superhydrophobic sand, the evaporation rate of soil moisture will be reduced by 56 to 78%, and the superhydrophobic sand after covering will promote the growth of crops such as tomatoes and wheat. But on the other hand, solid paraffin will become liquid at 50-65°C and migrate downward, causing the superhydrophobic sand to lose its superhydrophobicity. In many areas, the summer surface temperature will exceed 50°C to 65°C, or even 75°C, so the application area and season of the superhydrophobic sand are very limited. For example, Chen and his collaborators [CHEN C, PENGX. Constructing superhydrophobic sands layer with PTFE nanocoating for desertwater storage and oil / water separation [J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2023, 657] used polyelectrolyte polydiallyldimethylammonium chloride and polytetrafluoroethylene nanoparticles to modify desert sand to prepare superhydrophobic sand and use it for desert water storage. Although the superhydrophobic sand prepared by the above method can achieve desert water storage to a certain extent, this method will bring new organic pollutants, especially fluorine-containing compounds, which will cause great safety hazards to the ecological environment.In addition to the above methods for preparing superhydrophobic sand, the following methods have also successfully prepared superhydrophobic sand, such as Guo Zhiguang et al. [A method for preparing superhydrophobic sand [P]. Chinese patent: CN 106866010 A, 2017.06.20] First, a phase transfer catalyst was used to catalyze tetraethyl orthosilicate to cover a layer of silica on the surface of the sand, and then superhydrophobic sand was prepared by the modification method of perfluorodecyltriethoxysilane; Song Yongsheng et al. [Preparation method of superhydrophobic sand and its application method in desert ecological restoration and management [P]. Chinese Patent: CN111704477A, ​​2020.09.25] Superhydrophobic sand was prepared by multi-step modification of sand with hydrogen-containing siloxane polymer emulsion and surfactant; Chen Chaolang et al. [A superhydrophobic sand grain and its preparation method and application [P]. Chinese Patent: CN115353117A, 2022.11.18] The sand was modified with polyelectrolyte to make it positively charged, and then polytetrafluoroethylene colloidal particles were used for modification to successfully prepare superhydrophobic sand. Although the above methods have successfully prepared superhydrophobic sand, these methods all have complex preparation processes and require the use of compounds such as phase transfer catalysts, emulsifiers or polyelectrolytes. There are also problems such as the use of fluorine-containing or silicon-containing compounds or polymers that are harmful to the environment and secondary pollution caused by use, especially plastic pollution. Summary of the invention

[0005] The purpose of the present invention is to address the problems existing in the prior art and first provide a super-hydrophobic sand-based composite material, which can not only retain water in the soil but also has no potential secondary pollution to the environment.

[0006] Another object of the present invention is to provide a method for preparing the above-mentioned super-hydrophobic sand-based composite material.

[0007] The present invention provides a super-hydrophobic sand-based composite material, characterized in that the composite material is composed of a layered and porous micro-nano structure prepared by reacting sand, biochar, zinc oxide and an organic acid, the super-hydrophobic sand-based composite material has a water contact angle greater than 150° in the air, a rolling angle less than 10°, and is treated at -80°C and 110°C for 6 hours as a cycle. After 20 cycles of treatment, the water contact angle is still greater than 150°, and the rolling angle is still less than 10°; after the super-hydrophobic sand-based composite material is used to cover the soil for 8 days, the evaporation rate of soil moisture is reduced by 50-95%.

[0008] The sand described in the above super-hydrophobic sand-based composite material is at least one of western Sichuan plateau sand, Qinghai-Tibet Plateau sand, river sand, sea sand, quartz sand, aeolian sand, Kubuqi Desert sand, Taklimakan Desert sand and artificial sand.

[0009] The biochar described in the above superhydrophobic sand-based composite material is at least one of corn straw biochar, rape straw biochar, wheat straw biochar, rice straw biochar, sorghum straw biochar, bamboo biochar, peanut shell biochar, rice husk biochar, walnut shell biochar and bagasse biochar.

[0010] The organic acid described in the above superhydrophobic sand-based composite material is at least one of butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, linoleic acid and oleic acid.

[0011] The size of the zinc oxide in the above super-hydrophobic sand-based composite material is 1 nm to 800 μm, preferably 10 to 500 nm.

[0012] The water contact angle mentioned above is the static contact angle θ between the material surface and water. When the contact angle θ between the material and water is 0°, water can well infiltrate the material surface, and the material is super-hydrophilic at this time; when the contact angle is 0°≤θ<90°, water can infiltrate the material surface, and the material is also hydrophilic at this time; when the contact angle is 90°≤θ<150°, water cannot infiltrate the material surface, and the material is hydrophobic at this time; when the contact angle is 150°≤θ≤180°, water cannot infiltrate the material surface at all, and the material is super-hydrophobic at this time. The smaller the rolling angle of the solid surface, the less adhesion the surface of the material has to the droplet being characterized, and the easier it is for the droplet to roll on this surface.

[0013] The present invention provides a method for preparing the above-mentioned super-hydrophobic sand-based composite material, and the process steps and conditions of the method are as follows:

[0014] (1) First, dry sand, biochar and zinc oxide are mixed evenly according to the mass ratio of sand, biochar and zinc oxide of 100: (0.1-60): (0.1-50) and set aside;

[0015] (2) Add the above mixture to a 0.1-50% by mass stearic acid ethanol solution, react at -20-90° C. for 0.5-48 h, filter and dry the obtained solid.

[0016] The sand used in the above preparation method is at least one of western Sichuan plateau sand, Qinghai-Tibet Plateau sand, river sand, sea sand, quartz sand, aeolian sand, Kubuqi Desert sand, Taklimakan Desert sand and artificial sand.

[0017] The biochar used in the above preparation method is at least one of corn straw biochar, rape straw biochar, wheat straw biochar, rice straw biochar, sorghum straw biochar, bamboo biochar, peanut shell biochar, rice husk biochar, walnut shell biochar and bagasse biochar.

[0018] The organic acid used in the above preparation method is at least one of butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, linoleic acid and oleic acid.

[0019] The average size of zinc oxide used in the above preparation method is 1 nm to 800 μm.

[0020] The sand used in the above preparation method is preferably sand from the western Sichuan plateau, sand from the Qinghai-Tibet Plateau, river sand and aeolian sand.

[0021] The biochar used in the above preparation method is preferably corn straw biochar, rape straw biochar, wheat straw biochar, rice straw biochar and sorghum straw biochar.

[0022] The average size of zinc oxide used in the above preparation method is preferably 10 to 500 nm.

[0023] The mass fraction of the stearic acid ethanol solution used in the above preparation method is preferably (5-20)%.

[0024] The reaction temperature in the above preparation method is preferably 5 to 35°C.

[0025] The reaction time in the above preparation method is preferably 0.5 to 12 h.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. Since the super-hydrophobic sand-based composite material provided by the present invention is obtained by a one-step reaction of heat-resistant and low-temperature-resistant reagents, the water contact angle of the material is still greater than 150° and the rolling angle is still less than 10° after multiple cycles of treatment at -80°C and 110°C, indicating that it can be stably used in extremely low and high temperature areas.

[0028] 2. The super-hydrophobic sand-based composite material provided by the present invention not only has super-hydrophobicity, but also has a micro-nano flake and porous structure. It is these small micropores and tightly stacked lamellar structures that significantly enhance its water retention capacity. After covering the soil with it, the evaporation rate of soil moisture can be reduced to a maximum of 95%.

[0029] 3. Since the preparation method provided by the present invention can avoid the use of phase transfer catalysts, emulsifiers, polyelectrolytes, fluorine-containing or silicon-containing compounds or polymers required in traditional methods, it can avoid the harm of composite materials to the environment in practical applications, as well as the secondary plastic pollution caused after use.

[0030] 4. Since the raw materials used to prepare the superhydrophobic sand-based composite material provided by the present invention, such as sand, biochar, organic acid, etc., are from a wide range of sources and are all natural products or derivatives of natural products, and some of the raw materials are commercially available, and other raw materials are also commercially available raw materials and easy to obtain, the preparation cost can be greatly reduced, which is more conducive to large-scale production.

[0031] 5. Since the method provided by the present invention only requires one simple reaction step to prepare a super-hydrophobic sand-based composite material, the preparation process is simple, energy consumption is low, time consumption is short, and no complex equipment is required. In addition, the materials and reagents used are environmentally friendly, with little toxic and side effects. No pollutants such as organic fluorine and organic silicon are generated before and after the reaction, and large-scale production is possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a scanning electron microscope photo of the super-hydrophobic sand-based composite material prepared in Example 21 of the present invention. From the photo, it can be seen that it has a flaky and porous structure, so it can effectively reduce water evaporation and achieve a water retention effect.

[0033] Figure 2 The contact angle photograph of the super-hydrophobic sand-based composite material prepared in Example 21 of the present invention after being frozen at -80°C for 6 hours and then treated at 110°C for 6 hours, and subjected to 20 cycles of such freezing and heating treatments. As can be seen from the photograph, its contact angle can still be greater than 150°, that is, it is in a super-hydrophobic state.

[0034] Figure 3 This is a photo of the rolling angle of the super-hydrophobic sand-based composite material prepared in Example 21 of the present invention after being frozen at -80°C for 6 hours and then treated at 110°C for 6 hours, and subjected to 20 cycles of such freezing and heating. As can be seen from the photo, its rolling angle is still less than 10°, so it presents a low-adhesion super-hydrophobic state.

[0035] Figure 4 The following are photos of ryegrass grown on soil covered with the super-hydrophobic sand-based composite material prepared in Example 21 of the present invention and not covered with the above-mentioned sand after 15 days of growth. The left side is a photo of ryegrass growth not covered with the super-hydrophobic sand-based composite material, and the right side is a photo of ryegrass growth covered with the super-hydrophobic sand-based composite material. It can be seen from the photo comparison that after covering the super-hydrophobic sand-based composite material, the ryegrass grows more uniformly and the growth height is closer. DETAILED DESCRIPTION

[0036] The following embodiments are given to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It is worth noting that 1) the water contact angle of the material in the air is measured by the following method: the prepared material and the material that has been frozen at -80°C for 6 hours and then treated at 110°C for 6 hours and cycled 20 times are spread on the surface of a glass slide and placed horizontally on the working platform of a water contact angle tester. A microinjector is used to drop 2 to 5 μL of water on the surface of the material. After 5 seconds, the morphology of the water drop is photographed and the water contact angle value is measured. At least 5 different positions are tested, and the average contact angle of all positions is calculated as the final result of the contact angle of the material surface. 2) The rolling angle of the material in the air is measured by the following method: the prepared material and the material that has been frozen at -80°C for 6 hours and then treated at 110°C for 6 hours, and then cycled 20 times are spread on the surface of a glass slide, and placed horizontally on the working platform of a water contact angle tester. The test platform is then slowly rotated, and 2 to 5 μL of water is dropped on the surface of the material using a microinjector. When the water drop starts to roll, the rotation is stopped. At this time, the rotation angle of the platform is the rolling angle value of the material. The test is repeated at least 5 times, and the average value is calculated as the final result of the rolling angle of the material. 3) The soil moisture evaporation rate is measured by the following method: Soil with a humidity of H1 is placed in a beaker, and a certain thickness of superhydrophobic sand-based composite material is covered on its surface. The soil humidity H2 is tested every t hours, and the moisture evaporation rate 4) The reduction ratio of soil moisture evaporation rate was measured as follows: the original soil moisture evaporation rate without covering the super-hydrophobic sand-based composite material was P1, and the soil moisture evaporation rate covered with 5 mm thick super-hydrophobic sand-based composite material was P2. When the reduction value is less than 0, it means that the evaporation rate of water is accelerated after covering the super-hydrophobic sand-based composite material. When the reduction value is equal to 0, it means that the soil moisture increase rate remains unchanged after covering the super-hydrophobic sand-based composite material. When the reduction value is greater than 0, it means that the soil moisture evaporation value is reduced after covering the super-hydrophobic sand-based composite material. 5) The cyclic temperature resistance test is measured by the following method: the super-hydrophobic sand is frozen at -80℃ for 6h and then treated at 110℃ for 6h. The above is a treatment cycle; after each treatment cycle, the contact angle and rolling angle of the material are tested according to the methods given in 1) and 2).

[0038] Example 1

[0039] First, dry Taklimakan Desert sand, bamboo biochar, and zinc oxide with a size of 1 nm were weighed and mixed at a mass ratio of 100:0.1:0.1, and then added to a butyric acid ethanol solution containing a mass fraction of 0.1%, and reacted at 20°C for 6 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0040] The prepared super-hydrophobic sand-based composite material has a water contact angle of 150±2° and a rolling angle of 7±1° in the air. After 20 cycles of treatment at -80°C and 110°C for 6 hours, its water contact angle in the air is 151±2° and its rolling angle is 6±3°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 50%.

[0041] Example 2

[0042] First, dry quartz sand, bagasse biochar, and zinc oxide with a size of 10 nm were weighed and mixed evenly in a mass ratio of 100:0.1:5, and then added to a 1% valeric acid ethanol solution and reacted at 25°C for 5 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0043] The prepared super-hydrophobic sand-based composite material has a water contact angle of 154±3° and a rolling angle of 5±2° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 152±1° and the rolling angle is 8±1°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 54%.

[0044] Example 3

[0045] First, dry western Sichuan plateau sand, river sand and aeolian sand (the mass ratio of the three types of sand is 1:1:1), rice husk biochar, and zinc oxide with a size of 50 nm are weighed and mixed evenly at a mass ratio of 100:0.1:25, and then put into a 5% hexanoic acid ethanol solution and react at 30°C for 8 hours. After the reaction is completed, the mixture is filtered to obtain a solid, and the solid is dried at 45°C.

[0046] The prepared super-hydrophobic sand-based composite material has a water contact angle of 155±2° and a rolling angle of 6±1° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 156±1° and the rolling angle is 6±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 58%.

[0047] Example 4

[0048] First, dry sea sand, peanut shell biochar and rice husk biochar (the mass ratio of the two biochars is 1:2) and zinc oxide with a size of 100 nm are weighed and mixed evenly according to the mass ratio of 100:12:6, and then put into a 10% lauric acid ethanol solution and react at 35°C for 0.5h. After the reaction is completed, the mixture is filtered to obtain a solid, and the solid is dried at 45°C.

[0049] The prepared super-hydrophobic sand-based composite material has a water contact angle of 157±3° and a rolling angle of 5±2° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 156±2° and the rolling angle is 7±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 60%.

[0050] Example 5

[0051] First, dry Kubuqi desert sand, sorghum straw biochar, and zinc oxide with a size of 200 nm were weighed and mixed evenly in a mass ratio of 100:15:20, and then added to a 15% 15-decadecanoic acid ethanol solution and reacted at 40°C for 14 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0052] The prepared super-hydrophobic sand-based composite material has a water contact angle of 163±1° and a rolling angle of 7±2° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 160±3° and the rolling angle is 6±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 63%.

[0053] Example 6

[0054] First, dry artificial sand, bagasse biochar, and zinc oxide with a size of 300 nm were weighed and mixed evenly in a mass ratio of 100:60:25, and then added to a 20% mass fraction of ethanol solution of capric acid and reacted at 45°C for 7 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0055] The prepared super-hydrophobic sand-based composite material has a water contact angle of 169±1° and a rolling angle of 2±1° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 163±2° and the rolling angle is 8±1°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 68%.

[0056] Example 7

[0057] First, the dried western Sichuan plateau sand, rape straw biochar, and zinc oxide with a size of 400 nm were weighed and mixed evenly in a mass ratio of 100:10:5, and then added to an ethanol solution containing 25% of undecanoic acid by mass and reacted at 50°C for 4 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0058] The prepared super-hydrophobic sand-based composite material has a water contact angle of 158±4° and a rolling angle of 4±2° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 152±3° and the rolling angle is 7±1°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 75%.

[0059] Example 8

[0060] First, dry aeolian sand, wheat straw biochar, and zinc oxide with a size of 500 nm were weighed and mixed evenly in a mass ratio of 100:30:20, and then added to a 30% octanoic acid ethanol solution and reacted at 60°C for 8 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0061] The prepared super-hydrophobic sand-based composite material has a water contact angle of 157±1° and a rolling angle of 2±1° in the air. After being treated at -80℃ and 110℃ for 6 hours in one cycle, after 20 treatments, its water contact angle in the air is 154±2° and the rolling angle is 5±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 77%.

[0062] Example 9

[0063] First, dry river sand, corn straw biochar and rape straw biochar (the mass ratio of the two straws is 1:3) and zinc oxide with a size of 600 nm are weighed and mixed evenly according to the mass ratio of 100:15:10, and then put into a tridecanoic acid ethanol solution containing a mass fraction of 35%, and react at 70°C for 20 hours. After the reaction is completed, the mixture is filtered to obtain a solid, and the solid is dried at 45°C.

[0064] The prepared super-hydrophobic sand-based composite material has a water contact angle of 152±2° and a rolling angle of 7±1° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 153±1° and the rolling angle is 8±1°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 82%.

[0065] Example 10

[0066] First, dry artificial sand, peanut shell biochar, and zinc oxide with a size of 700 nm were weighed and mixed evenly in a mass ratio of 100:60:5, and then added to an ethanol solution containing 40% myristic acid by mass and reacted at -5°C for 6 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0067] The prepared super-hydrophobic sand-based composite material has a water contact angle of 156±1° and a rolling angle of 8±1° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 157±2° and the rolling angle is 6±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 88%.

[0068] Embodiment 11

[0069] First, dry Kubuqi desert sand, bamboo biochar, and zinc oxide with a size of 800 nm were weighed and mixed evenly in a mass ratio of 100:40:35, and then added to an ethanol solution containing 45% heptanoic acid by mass and reacted at 90°C for 3 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0070] The prepared super-hydrophobic sand-based composite material has a water contact angle of 151±3° and a rolling angle of 5±2° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 156±2° and the rolling angle is 8±1°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 91%.

[0071] Example 12

[0072] First, dry western Sichuan plateau sand, Qinghai-Tibet Plateau sand and aeolian sand (the mass ratio of the three types of sand is 2:1:1), corn straw biochar, and zinc oxide with a size of 5 nm are weighed and mixed at a mass ratio of 100:50:18, and then put into a palmitic acid ethanol solution containing 50% by mass fraction, and react at -20°C for 2h. After the reaction is completed, the mixture is filtered to obtain a solid, and the solid is dried at 45°C.

[0073] The prepared super-hydrophobic sand-based composite material has a water contact angle of 154±3° and a rolling angle of 8±1° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 154±2° and the rolling angle is 7±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 95%.

[0074] Embodiment 13

[0075] First, dry Qinghai-Tibet Plateau sand, rape straw biochar, and zinc oxide with a size of 15 nm were weighed and mixed evenly in a mass ratio of 100:0.5:15, and then added to an ethanol solution containing 2% linoleic acid by mass and reacted at -10°C for 4 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0076] The prepared super-hydrophobic sand-based composite material has a water contact angle of 157±2° and a rolling angle of 6±3° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 152±1° and the rolling angle is 6±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 52%.

[0077] Embodiment 14

[0078] First, dry sea sand, wheat straw biochar, and zinc oxide with a size of 20 nm were weighed and mixed evenly in a mass ratio of 100:12:18, and then added to an ethanol solution containing 6% linoleic acid by mass and reacted at 0°C for 3 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0079] The prepared super-hydrophobic sand-based composite material has a water contact angle of 159±3° and a rolling angle of 7±1° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 154±1° and the rolling angle is 5±3°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 63%.

[0080] Embodiment 15

[0081] First, dry Qinghai-Tibet Plateau sand, rice husk biochar, and zinc oxide with a size of 30 nm were weighed and mixed in a mass ratio of 100:45:5, and then added to an ethanol solution containing 8% of stearic acid, lauric acid, and oleic acid (the mass ratio of the three is 1:1:1) and reacted at 5°C for 4 hours. After the reaction is completed, the mixture is filtered to obtain a solid, and the solid is dried at 45°C.

[0082] The prepared super-hydrophobic sand-based composite material has a water contact angle of 163±3° and a rolling angle of 6±1° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 158±1° and the rolling angle is 6±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 74%.

[0083] Example 16

[0084] First, dry western Sichuan plateau sand and river sand (the mass ratio of the two sands is 3:1), rice platycodon biochar, and zinc oxide with a size of 45nm are weighed and mixed evenly according to the mass ratio of 100:42:28, and then put into an oleic acid ethanol solution containing a mass fraction of 12% and reacted at 10°C for 1h. After the reaction is completed, the mixture is filtered to obtain a solid, and the solid is dried at 45°C.

[0085] The prepared super-hydrophobic sand-based composite material has a water contact angle of 167±2° and a rolling angle of 6±3° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, the water contact angle in the air is 164±1° and the rolling angle is 8±1° after 20 treatments. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 83%.

[0086] Embodiment 17

[0087] First, dry Qinghai-Tibet Plateau sand, peanut shell biochar, rape straw biochar and bagasse biochar (the mass ratio of the three biochars is 1:2:1) and zinc oxide with a size of 250nm are weighed and mixed at a mass ratio of 100:18:32, and then put into an ethanol solution containing 18% hexanoic acid by mass and reacted at -18°C for 10 hours. After the reaction is completed, the mixture is filtered to obtain a solid, and the solid is dried at 45°C.

[0088] The prepared super-hydrophobic sand-based composite material has a water contact angle of 155±3° and a rolling angle of 8±2° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 152±2° and the rolling angle is 7±1°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 80%.

[0089] Embodiment 18

[0090] First, dry Taklimakan Desert sand, corn straw biochar, and zinc oxide with a size of 350 nm were weighed and mixed evenly in a mass ratio of 100:0.1:50, and then added to a 24% ethanol solution of pentadecanoic acid and reacted at -14°C for 12 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0091] The prepared super-hydrophobic sand-based composite material has a water contact angle of 152±3° and a rolling angle of 8±1° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 151±2° and the rolling angle is 6±1°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 86%.

[0092] Embodiment 19

[0093] First, the dried western Sichuan plateau sand, rape straw biochar, and zinc oxide with a size of 450 nm were weighed and mixed evenly in a mass ratio of 100:30:0.1, and then added to a 32% mass fraction of ethanol solution of decanoic acid and reacted at -12°C for 0.5h. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0094] The prepared super-hydrophobic sand-based composite material has a water contact angle of 158±2° and a rolling angle of 7±1° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 154±3° and the rolling angle is 6±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 52%.

[0095] Embodiment 20

[0096] First, dry sea sand, sorghum straw biochar, and zinc oxide with a size of 650 nm were weighed and mixed evenly according to the mass ratio of sand, biochar, and zinc oxide of 100:20:2, and then put into a 48% valeric acid ethanol solution and reacted at -8°C for 5 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0097] The prepared super-hydrophobic sand-based composite material has a water contact angle of 151±1° and a rolling angle of 5±2° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 152±2° and the rolling angle is 7±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 56%.

[0098] Embodiment 21

[0099] First, dry river sand, corn straw biochar, and zinc oxide with a size of 30 nm were weighed and mixed evenly in a mass ratio of 100:10:8, and then added to a stearic acid ethanol solution containing 5% by mass fraction and reacted at 80°C for 1 hour. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0100] The water contact angle of the prepared super-hydrophobic sand-based composite material in the air is 152±2°, and the rolling angle is 6±1°. After being treated at -80℃ and 110℃ for 6h in one cycle, the water contact angle in the air is 152±1° and the rolling angle is 7±1° after 20 treatments. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 68%.

[0101] Embodiment 22

[0102] First, dry aeolian sand, rice platycodon biochar, and zinc oxide with a size of 720 nm were weighed and mixed evenly in a mass ratio of 100:20:10, and then added to an ethanol solution containing 22% lauric acid by mass and reacted at 4°C for 36 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0103] The water contact angle of the prepared super-hydrophobic sand-based composite material in the air was 169±1°, and the rolling angle was 6±3°. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, the water contact angle in the air was 165±2°, and the rolling angle was 8±1°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water was reduced by 72%.

[0104] Embodiment 23

[0105] First, dry Taklimakan Desert sand, sorghum straw biochar, and zinc oxide with a size of 400 nm were weighed and mixed evenly in a mass ratio of 100:60:50, and then added to a butyric acid ethanol solution containing a mass fraction of 26%, and reacted at 5°C for 15 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0106] The water contact angle of the prepared super-hydrophobic sand-based composite material in the air was 157±2°, and the rolling angle was 8±1°. After being treated at -80℃ and 110℃ for 6 hours in a cycle, after 20 treatments, the water contact angle in the air was 154±3°, and the rolling angle was 8±1°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the soil moisture evaporation rate was reduced by 77%

[0107] Embodiment 24

[0108] First, dry western Sichuan plateau sand and Qinghai-Tibet Plateau sand (the mass ratio of the two sands is 1:1), rape straw biochar, and zinc oxide with a size of 360nm are weighed and mixed at a mass ratio of 100:10:0.1, and then put into an ethanol solution containing 33% of undecanoic acid by mass fraction, and react at 8°C for 5h. After the reaction is completed, the mixture is filtered to obtain a solid, and the solid is dried at 45°C.

[0109] The prepared super-hydrophobic sand-based composite material has a water contact angle of 150±1° and a rolling angle of 6±2° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 153±3° and the rolling angle is 6±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 75%.

[0110] Embodiment 25

[0111] First, dry quartz sand, peanut shell biochar, and zinc oxide with a size of 125 nm were weighed and mixed evenly in a mass ratio of 100:30:50, and then added to a 34% heptanoic acid ethanol solution and reacted at 10°C for 6 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0112] The prepared super-hydrophobic sand-based composite material has a water contact angle of 156±2° and a rolling angle of 7±2° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 152±1° and the rolling angle is 6±3°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 76%.

[0113] Embodiment 26

[0114] First, dry western Sichuan plateau sand, corn straw biochar and rice husk biochar (the mass ratio of the two biochars is 3:1), and zinc oxide with a size of 200 nm are weighed and mixed at a mass ratio of 100:22:40, and then put into a palmitic acid ethanol solution containing a mass fraction of 29%, and react at 15°C for 7 hours. After the reaction is completed, the mixture is filtered to obtain a solid, and the solid is dried at 45°C.

[0115] The prepared super-hydrophobic sand-based composite material has a water contact angle of 161±1° and a rolling angle of 8±1° in the air. After being treated at -80°C and 110°C for 6 hours in one cycle, after 20 treatments, its water contact angle in the air is 156±2° and the rolling angle is 7±1°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 80%.

[0116] Embodiment 27

[0117] First, dry Kubuqi desert sand, rice husk biochar, and zinc oxide with a size of 300 nm were weighed and mixed evenly in a mass ratio of 100:5:15, and then added to a 41% octanoic acid ethanol solution and reacted at 18°C ​​for 48 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0118] The prepared super-hydrophobic sand-based composite material has a water contact angle of 158±2° and a rolling angle of 7±2° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, the water contact angle in the air is 153±4° and the rolling angle is 8±1° after 20 cycles. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 83%.

[0119] Embodiment 28

[0120] First, dry aeolian sand, bamboo biochar, and zinc oxide with a size of 400 nm were weighed and mixed evenly in a mass ratio of 100:10:25, and then added to a 14% mass fraction tridecanoic acid ethanol solution and reacted at 25°C for 5 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0121] The prepared super-hydrophobic sand-based composite material has a water contact angle of 162±3° and a rolling angle of 3±2° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 159±2° and the rolling angle is 5±3°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 82%.

[0122] Embodiment 29

[0123] First, dry western Sichuan plateau sand and artificial sand (the mass ratio of the two sands is 2:1), sugarcane bagasse biochar, and zinc oxide with a size of 500nm are weighed and mixed evenly at a mass ratio of 100:10:20, and then put into a butyric acid ethanol solution containing a mass fraction of 20%, and react at 30°C for 2h. After the reaction is completed, the mixture is filtered to obtain a solid, and the solid is dried at 45°C.

[0124] The water contact angle of the prepared super-hydrophobic sand-based composite material in the air was 154±2°, and the rolling angle was 8±1°. After being treated at -80℃ and 110℃ for 6 hours in one cycle, the water contact angle in the air was 156±1° and the rolling angle was 7±1° after 20 treatments. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water was reduced by 89%.

[0125] Embodiment 30

[0126] First, dry quartz sand, wheat straw biochar, and zinc oxide with a size of 50 nm were weighed and mixed evenly in a mass ratio of 100:16:24, and then added to an ethanol solution containing 25% myristic acid by mass and reacted at 32°C for 5 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0127] The water contact angle of the prepared super-hydrophobic sand-based composite material in the air was 161±4°, and the rolling angle was 7±1°. After being treated at -80°C and 110°C for 6 hours in one cycle, after 20 treatments, the water contact angle in the air was 153±4°, and the rolling angle was 6±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water was reduced by 92%.

[0128] Embodiment 31

[0129] First, dry aeolian sand and river sand (the mass ratio of the two sands is 4:1), peanut shell biochar, rape straw biochar and rice husk biochar (the mass ratio of the three biochars is 1:2:1), and zinc oxide with a size of 25nm are weighed and mixed at a mass ratio of 100:10:50, and then put into an ethanol solution containing 30% stearic acid and oleic acid (the mass ratio of the two is 1:1) and react at 65°C for 6h. After the reaction is completed, the mixture is filtered to obtain a solid, and the solid is dried at 45°C.

[0130] The water contact angle of the prepared super-hydrophobic sand-based composite material in the air was 165±4°, and the rolling angle was 8±1°. After being treated at -80°C and 110°C for 6 hours in one cycle, after 20 treatments, the water contact angle in the air was 154±1°, and the rolling angle was 8±1°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water was reduced by 93%.

[0131] Embodiment 32

[0132] First, dry Qinghai-Tibet Plateau sand, peanut shell biochar, and zinc oxide with a size of 10 nm were weighed and mixed evenly in a mass ratio of 100:25:25, and then added to an oleic acid ethanol solution containing 50% by mass fraction and reacted at 75°C for 7 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0133] The prepared super-hydrophobic sand-based composite material has a water contact angle of 155±1° and a rolling angle of 6±3° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 156±3° and the rolling angle is 7±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 65%.

[0134] Embodiment 33

[0135] First, dry river sand, corn straw biochar, and zinc oxide with a size of 16 nm were weighed and mixed evenly in a mass ratio of 100:60:0.1, and then added to a stearic acid ethanol solution containing a mass fraction of 0.5%, and reacted at 85°C for 3 hours. After the reaction was completed, the mixture was filtered to obtain a solid, and the solid was dried at 45°C.

[0136] The prepared super-hydrophobic sand-based composite material has a water contact angle of 150±4° and a rolling angle of 8±1° in the air. After being treated at -80°C and 110°C for 6 hours in one cycle, after 20 treatments, its water contact angle in the air is 150±1° and the rolling angle is 6±2°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 79%.

[0137] Embodiment 34

[0138] First, the dried western Sichuan plateau sand, rice straw biochar, and zinc oxide with a size of 350nm were weighed and mixed in a mass ratio of 100:24:12, and then put into an ethanol solution containing 1.5% of stearic acid and lauric acid (the mass ratio of the two organic acids is 2:1) and reacted at 90°C for 1h. After the reaction is completed, the mixture is filtered to obtain a solid, and the solid is dried at 45°C.

[0139] The prepared super-hydrophobic sand-based composite material has a water contact angle of 153±2° and a rolling angle of 7±1° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 151±1° and the rolling angle is 8±1°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 86%.

[0140] Embodiment 35

[0141] First, dry artificial sand, wheat straw biochar and rice husk biochar (the mass ratio of the two biochars is 4:1), and zinc oxide with a size of 480nm are weighed and mixed at a mass ratio of 100:30:25, and then put into a 7.5% ethanol solution of pentadecanoic acid and react at 55°C for 9h. After the reaction is completed, the mixture is filtered to obtain a solid, and the solid is dried at 45°C.

[0142] The prepared super-hydrophobic sand-based composite material has a water contact angle of 154±1° and a rolling angle of 6±3° in the air. After being treated at -80℃ and 110℃ for 6h in one cycle, after 20 treatments, its water contact angle in the air is 152±3° and the rolling angle is 7±1°. After covering the wet soil surface with 5mm of the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil water is reduced by 91%.

Claims

1. A super-hydrophobic sand-based composite material, characterized in that The composite material is composed of a layered and porous micro-nano structure prepared by reacting sand, biochar, zinc oxide and organic acid. The water contact angle of the super-hydrophobic sand-based composite material in the air is greater than 150 degrees, and the rolling angle is less than 10 degrees. After being treated at -80 degrees Celsius and 110 degrees Celsius for 6 hours in a cycle, the water contact angle is still greater than 150 degrees, and the rolling angle is still less than 10 degrees after 20 cycles. After covering the soil with the super-hydrophobic sand-based composite material for 8 days, the evaporation rate of soil moisture is reduced by 50-95%.

2. The super-hydrophobic sand-based composite material according to claim 1, characterized in that The sand in the composite material is at least one of western Sichuan plateau sand, Qinghai-Tibet Plateau sand, river sand, sea sand, quartz sand, aeolian sand, Kubuqi desert sand, Taklimakan desert sand and artificial sand.

3. The super hydrophobic sand-based composite material according to claim 1 or 2, characterized in that The biochar in the composite material is at least one of corn straw biochar, rape straw biochar, wheat straw biochar, rice straw biochar, sorghum straw biochar, bamboo biochar, peanut shell biochar, rice husk biochar, walnut shell biochar and bagasse biochar.

4. The super-hydrophobic sand-based composite material according to claim 1 or 2, characterized in that The organic acid in the composite material is at least one of butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, linoleic acid and oleic acid.

5. The super-hydrophobic sand-based composite material according to claim 3, characterized in that The organic acid in the composite material is at least one of butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, linoleic acid and oleic acid.

6. A method for preparing the super-hydrophobic sand-based composite material according to claim 1, wherein the process steps and conditions of the method are as follows: (1) First, dry sand, biochar and zinc oxide are mixed evenly according to the mass ratio of sand, biochar and zinc oxide of 100: (0.1-60): (0.1-50) and set aside; (2) Add the above mixture to a 0.1-50% by mass stearic acid ethanol solution, react at -20-90° C. for 0.5-48 h, filter and dry the obtained solid.

7. The method for preparing a super hydrophobic sand-based composite material according to claim 6, wherein The sand used in the method is at least one of western Sichuan plateau sand, Qinghai-Tibet Plateau sand, river sand, sea sand, quartz sand, aeolian sand, Kubuqi Desert sand, Taklimakan Desert sand and artificial sand.

8. The method for preparing a super hydrophobic sand-based composite material according to claim 6 or 7, characterized in that The biochar used in the method is at least one of corn straw biochar, rape straw biochar, wheat straw biochar, rice straw biochar, sorghum straw biochar, bamboo biochar, peanut shell biochar, rice husk biochar, walnut shell biochar and bagasse biochar.

9. The method for preparing a super hydrophobic sand-based composite material according to claim 6 or 7, wherein The organic acid used in the method is at least one of butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, linoleic acid and oleic acid.

10. The method for preparing a super-hydrophobic sand-based composite material according to claim 8, characterized in that The organic acid used in the method is at least one of butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, linoleic acid and oleic acid; the average size of the zinc oxide used in the above preparation method is 1nm to 800μm.

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