阅读说明：本技术 超疏水沙子的制备方法及其在沙漠生态修复治理中的应用方法 (Preparation method of super-hydrophobic sand and application method thereof in desert ecological restoration treatment ) 是由 宋永生 于 2020-06-10 设计创作，主要内容包括：超疏水沙子的制备方法及其在沙漠生态修复治理中的应用方法涉及沙漠生态修复治理领域。主要是为解决目前沙漠中雨水高温蒸发和向地下无限量渗透等问题而发明的。把沙子与超疏水乳液充分均匀混合,直到所有沙粒都被乳液浸湿,然后自然晾干或烘干,待处理的沙子完全干燥后就形成了超疏水沙子。在种植沙层上方即表层铺盖一层超疏水防蒸发沙层或/和在沙漠种植沙层下方铺垫一层防止水分向下渗透的超疏水防渗沙层。优点是可抑制水分蒸发,阻止或隔断种植沙层中的水分向下渗透。(A preparation method of super-hydrophobic sand and an application method thereof in desert ecological restoration treatment relate to the field of desert ecological restoration treatment. The invention mainly aims to solve the problems of high-temperature evaporation of rainwater, unlimited infiltration to the underground and the like in the prior desert. And fully and uniformly mixing the sand and the super-hydrophobic emulsion until all sand grains are soaked by the emulsion, naturally airing or drying, and completely drying the sand to be treated to form the super-hydrophobic sand. And a super-hydrophobic anti-evaporation sand layer is paved above the planting sand layer, namely the surface layer, or/and a super-hydrophobic anti-seepage sand layer for preventing water from downwards permeating is paved below the desert planting sand layer. The method has the advantages of inhibiting the evaporation of water and preventing or blocking the downward permeation of water in the planting sand layer.)

1. The preparation method of the super-hydrophobic sand is characterized by comprising the following steps: and fully and uniformly mixing the sand and the super-hydrophobic emulsion until all sand grains are soaked by the emulsion, naturally airing or heating and drying, and completely drying the sand to be treated to form the super-hydrophobic sand.

2. The method for preparing the superhydrophobic sand of claim 1, wherein: the temperature of natural drying or heating and drying is not more than 150 ℃.

3. The method for preparing the superhydrophobic sand of claim 1, wherein: the sand can be any sand, including river sand, sea sand, desert sand, artificial sand or sand soil, and the diameter size of the sand grains is not limited.

4. The method for preparing the superhydrophobic sand of claim 1, wherein: the weight ratio of the effective actives of the super hydrophobic emulsion to the weight of the sand may be 0.001% to 1%.

5. The method for preparing the superhydrophobic sand of claim 1, wherein: the super hydrophobic emulsion actives may be used at a concentration of 0.01% to 10%.

6. The application method of the super-hydrophobic sand in the desert ecological restoration treatment is characterized by comprising the following steps: the super-hydrophobic evaporation-preventing sand layer is laid on the surface of the planting sand layer, water volatilization caused by capillary phenomenon in the planting sand layer is cut off, the effect of inhibiting water evaporation in the lower planting sand layer is achieved, and various plants such as trees can be planted according to the method.

7. The application method of the super-hydrophobic sand in the desert ecological restoration treatment is characterized by comprising the following steps: a super-hydrophobic anti-seepage sand layer for preventing water from permeating downwards is laid below the planting sand layer to prevent the water for irrigation from continuously permeating downwards, so that the effects of water retention, soil moisture conservation and anti-seepage are achieved.

8. The application method of the super-hydrophobic sand in the desert ecological restoration treatment, which is characterized by comprising the following steps: the thickness of the surface layer super-hydrophobic sand covered above the planting sand layer for retaining water and inhibiting water evaporation is 1-20 cm.

9. The application method of the super-hydrophobic sand in the desert ecological restoration treatment, which is characterized by comprising the following steps: the thickness of the super-hydrophobic sand below the planting sand layer for water retention, soil moisture conservation and seepage prevention ranges from 2 cm to 30 cm, and the proper thickness is 5-15 cm generally.

10. The application method of the super-hydrophobic sand in the desert ecological restoration treatment is characterized by comprising the following steps: a super-hydrophobic evaporation-preventing sand layer is laid above the planting sand layer, namely the surface layer, and the water volatilization caused by the capillary phenomenon in the sand layer is cut off; a super-hydrophobic anti-seepage sand layer for preventing water from permeating downwards is laid below the desert planting sand layer to prevent the irrigated water from continuously permeating downwards, so that the effects of water retention, soil moisture conservation and anti-seepage are achieved.

Technical Field

The invention relates to the field of desert ecological restoration and treatment, in particular to a preparation method of super-hydrophobic sand and application of the super-hydrophobic sand in desert ecological restoration and treatment.

Background

At present, many attempts are made to prevent the spread of desertification, and ecological desert control or restoration which does not constitute pollution or secondary environmental damage and can be developed sustainably is a more ideal method. In the initial stage of desert ecological restoration, a desert environment suitable for plant growth is artificially created, such as providing the most basic water required by plant growth, more importantly, creating a good environment for desert water retention and moisture conservation and preventing water and nutrient loss, plants grow circularly for many years to generate a large amount of plant organic fiber substances and the like to form a water retention and moisture conservation organic matter sand layer together with sand carriers, and a benign growth environment for natural ecological restoration and circulation of plants is gradually formed, so that desert ecological restoration and treatment are fundamentally completed.

The most scarce essential element for the growth of plants in deserts is water, and under the condition of providing limited water amount by natural rainfall or artificial irrigation, how to preserve water and reduce the loss of water as much as possible is very important. The rain water loss in the desert is mainly caused by high-temperature evaporation and unlimited permeation to the underground, and in order to slow down water evaporation, if a layer of super-hydrophobic sand is paved on the surface layer to inhibit the volatilization of internal water, or a proper amount of wood fiber or lignin or plant degradation products with strong water absorption and the like are added on the surface layer of the desert, the water evaporation can be well inhibited; in order to prevent rainwater from permeating underground, the method adopted at present is to lay a layer of plastic film or polymer of chemical synthesis which is difficult to degrade on the lower floor of the desert, these methods have three main defects, firstly, the film is not breathable and is not suitable for the growth of plants; meanwhile, polymers such as plastics cause serious secondary pollution to the desert; the service life of the plastic film is also a problem in desert high-temperature environments.

Disclosure of Invention

The invention aims to provide a preparation method of super-hydrophobic sand which can inhibit water evaporation, has air permeability, achieves the functions of preserving water and soil moisture and preventing permeation and overcomes the serious defects generated by a plastic film method, and an application method thereof in desert ecological restoration treatment.

The purpose of the invention is realized as follows: fully and uniformly mixing 100 kg of sand and 10 kg of super-hydrophobic emulsion until all sand grains are soaked by the emulsion (no dry sand grains exist), naturally airing or drying, wherein the drying temperature is not more than 150 ℃, and the super-hydrophobic sand is formed after the sand to be treated is completely dried.

The sand can be any sand, including river sand, sea sand, desert sand, artificial sand or sand soil, and the diameter size of the sand grains is not limited.

The super hydrophobic emulsion effective actives weight to sand weight ratio may be any ratio of 0.001% to 1%.

The super hydrophobic emulsion actives may be used at a concentration of 0.01% to 10%.

The mixing method of the super-hydrophobic emulsion and the sand is not limited until all sand grains are uniformly soaked. The mixing method can be that the emulsion is directly sprayed on the desert and uniformly permeates to the required depth without stirring; or the mixture is sprayed and then mechanically stirred, so that the mixture is more uniform; or the mechanized spraying and the stirring are carried out simultaneously.

The method for ecological restoration of the desert by using the super-hydrophobic sand comprises the following steps:

the method comprises the following steps: the super-hydrophobic evaporation-preventing sand layer with the thickness of 1-20 cm is laid on the surface of the planting sand layer, water volatilization caused by capillary phenomenon in the planting sand layer is cut off, the effect of inhibiting water evaporation in the lower planting sand layer is achieved, and plants such as trees can be planted according to the method.

The second method comprises the following steps: a super-hydrophobic anti-seepage sand layer for preventing water from permeating downwards is laid below the planting sand layer to prevent the water for irrigation from continuously permeating downwards, so that the effects of water retention, soil moisture conservation and anti-seepage are achieved. The thickness of the super-hydrophobic sand below the planting sand layer for water retention, soil moisture conservation and seepage prevention ranges from 2 cm to 30 cm, and the proper thickness is 5-15 cm generally.

The third method comprises the following steps: a super-hydrophobic evaporation-preventing sand layer is laid above the planting sand layer, namely the surface layer, and the water volatilization caused by the capillary phenomenon in the sand layer is cut off; a super-hydrophobic anti-seepage sand layer for preventing water from permeating downwards is laid below the desert planting sand layer to prevent the irrigated water from continuously permeating downwards, so that the effects of water retention, soil moisture conservation and anti-seepage are achieved.

The planting sand layer can be common sand, or functional sand which has the function of absorbing water better or slowing down water evaporation or bonding sand after being treated, or the layered combination of the common sand and the functional sand, for example, the common sand is arranged above the super-hydrophobic sand layer, and the functional sand layer is arranged above or on the surface layer of the common sand layer. The thickness of the planting sand layer on the super-hydrophobic sand layer for preventing the downward penetration of moisture is 20 cm to 200 cm, and a suitable thickness is generally 50 cm to 100 cm.

The invention has the advantages that: the hydrophobic sand has the advantages of environmental protection, no pollution, water retention, air permeability, high temperature resistance, long service life and the like.

(1) When a layer of super-hydrophobic sand is laid above the planting sand layer, the moisture in the planting sand layer can be prevented from volatilizing upwards due to capillary phenomenon, so that the effect of inhibiting the evaporation of the moisture is achieved, the air permeability is achieved, and the requirement of rhizomes for air is met.

(2) When a layer of super-hydrophobic sand is paved below the planting sand layer, the super-hydrophobic sand layer firstly prevents or cuts off the downward permeation of the moisture in the planting sand layer, thereby achieving the functions of preserving water and soil moisture and preventing permeation.

(3) Meanwhile, the super-hydrophobic sand layer has good air permeability as common sand, and can well keep the ecological environment of up-down respiration of the underground sand layer and the surface sand layer.

(4) The high-temperature-resistant super-hydrophobic sand has longer service life. Therefore, the super-hydrophobic sand completely overcomes the serious defects generated by a plastic film method in the soil moisture conservation and seepage prevention ecological control of the desert. The super-hydrophobic sand technology can be applied to deserts, sand, sandy soil and other zones, or corresponding facilities.

Drawings

FIG. 1 is a schematic diagram of super-hydrophobic sand used for desert ecological restoration treatment in the invention;

FIG. 2 is a graph showing the results of comparing the water evaporation rates in sand for test 7 of the present invention.

Detailed Description

Fully and uniformly mixing 100 kg of sand and 10 kg of super-hydrophobic emulsion until all sand grains are soaked by the emulsion (no dry sand grains exist), naturally airing or drying by heating to 150 ℃, and completely drying the sand to be treated to form the super-hydrophobic sand.

The sand can be any sand, including river sand, sea sand, desert sand, artificial sand or sand soil, and the diameter size of the sand grains is not limited.

The super hydrophobic emulsion effective actives weight to sand weight ratio may be any ratio of 0.001% to 1%.

The super hydrophobic emulsion actives may be used at a concentration of 0.01% to 10%.

The mixing method of the super-hydrophobic emulsion and the sand is not limited until all sand grains are uniformly soaked. The mixing method can be that the emulsion is directly sprayed on the desert and uniformly permeates to the required depth without stirring; or the mixture is sprayed and then mechanically stirred, so that the mixture is more uniform; or the mechanized spraying and the stirring are carried out simultaneously.

Referring to fig. 1, method one: the super-hydrophobic evaporation-preventing sand layer with the thickness of 1-20 cm is laid on the surface of the planting sand layer, water volatilization caused by capillary phenomenon in the planting sand layer is cut off, the effect of inhibiting water evaporation in the lower planting sand layer is achieved, and plants such as trees can be planted according to the method.

The second method comprises the following steps: a super-hydrophobic anti-seepage sand layer for preventing water from permeating downwards is laid below the planting sand layer to prevent the water for irrigation from continuously permeating downwards, so that the effects of water retention, soil moisture conservation and anti-seepage are achieved. The thickness of the super-hydrophobic sand below the planting sand layer for water retention, soil moisture conservation and seepage prevention ranges from 2 cm to 30 cm, and the proper thickness is 5-15 cm generally.

The third method comprises the following steps: a super-hydrophobic evaporation-preventing sand layer is laid above the planting sand layer, namely the surface layer, and the water volatilization caused by the capillary phenomenon in the sand layer is cut off; a super-hydrophobic anti-seepage sand layer for preventing water from permeating downwards is laid below the desert planting sand layer to prevent the irrigated water from continuously permeating downwards, so that the effects of water retention, soil moisture conservation and anti-seepage are achieved.

The planting sand layer can be common sand, or functional sand which has the function of absorbing water better or slowing down water evaporation or bonding sand after being treated, or the layered combination of the common sand and the functional sand, for example, the common sand is arranged above the super-hydrophobic sand layer, and the functional sand layer is arranged above or on the surface layer of the common sand layer. The thickness of the planting sand layer on the super-hydrophobic sand layer for preventing the downward penetration of moisture is 20 cm to 200 cm, and a suitable thickness is generally 50 cm to 100 cm.

The preparation method of the super-hydrophobic emulsion comprises the following steps: is prepared from the following raw materials: active, emulsifier, water; wherein the active matter accounts for 1-70% of the total weight of the nano hydrophobic emulsion, the emulsifier accounts for 0.1-10% of the total weight of the nano hydrophobic emulsion, and the water accounts for 98.9-20% of the total weight of the nano hydrophobic emulsion; the content of active matter in industrial production can be from 1% to 70%, the content of active matter in the product depends on the requirement of the application object, and the concentrated solution can be simply diluted with water in any proportion in factory or construction site.

The active matter of the nano hydrophobic emulsion is hydrogen-containing siloxane polymer (also called hydrogen-containing silicone oil), the hydrogen content of the active matter of the nano hydrophobic emulsion is 0.1-1.7%, and the molecular formula of the hydrogen-containing siloxane polymer is as follows:

(R)3SiO [ RHSiO ] nsi (R) 3R = alkyl of 1-5 carbons;

the emulsifier is composed of a neutral surfactant and an anionic surfactant, and the mixing ratio of the two surfactants is not limited;

the neutral surfactant can be fatty alcohol, ether or ester compounds, or a mixture of the fatty alcohol, the ether or the ester compounds, and the mixing ratio is not limited;

the anionic surfactant is fatty sulfate, fatty sulfonate or fatty acid salt, or a mixture of the fatty sulfate, the fatty sulfonate and the fatty acid salt, and the mixing ratio is not limited;

the fatty alcohols may be: saturated or unsaturated alkanes containing at least 1 or more alcoholic hydroxyl groups (-OH) and 6-30 straight or branched chain carbons, and optionally 0-3 carboxyl groups (-COO-) derivatives. Such as lauryl alcohol, stearyl alcohol, and palmityl alcohol, and the like.

The ethers may be: saturated or unsaturated alkanes containing at least 1 or more ether groups (C-O-C) and at least two 6 to 30 straight or branched chain carbons, and also derivatives of polyethylene glycol, HO [ CH2CH2O ] n-H (n = 100-.

The ester compound may be: saturated or unsaturated fatty acid ester derivatives (-COOC-) containing 6-30 straight chain or branched chain carbons, and optionally 0-5 alcoholic hydroxyl groups, such as glyceryl distearate, glyceryl monostearate, etc.

The fatty acid or salt thereof may be: saturated or unsaturated fatty acids (-COOH) containing 6 to 30 straight or branched chain carbons or fatty acid salts (-COOM, M = Na, K, Ca, etc.) or fatty sulfate salts (ROSO 3-), or fatty sulfonate salts (RSO 3-), such as oleic acid, sodium laurate, sodium lauryl sulfate and sodium dodecyl sulfate.

The preparation method of the nano hydrophobic emulsion comprises the following steps:

dissolving emulsifier in hot water of 50-80 deg.C, and mechanically stirring the mixture for 30 min until uniform emulsion is formed; when the temperature of the emulsion is reduced to about 25 ℃ at room temperature, regulating the pH value to 7 +/-1 by using a small amount of 10% hydrochloric acid or 10% sodium hydroxide solution; the emulsion was then stirred with a high shear at 800 to 2000rpm while slowly adding the active, and the mixture after addition was stirred at high speed for 30 minutes until a homogeneous milky concentrated emulsion was formed. When in use, the concentrated solution can be simply diluted with water in any proportion to prepare nano hydrophobic diluted emulsion suitable for different applications.

The construction method for preparing the super-hydrophobic sand bed for desert control comprises the following steps:

the method comprises the following steps: the simple spraying method can uniformly and controllably spray the super-hydrophobic emulsion on the surface layer of the desert by using a water spraying vehicle or a spraying device, the spraying amount can be controlled to be 2-20 cm deep by naturally downward penetration of the emulsion, and then the desert is naturally dried. The hydrophobic sand layer can be used as a super-hydrophobic sand layer which is arranged above the planting sand layer and used for inhibiting water evaporation; for example, as a super-hydrophobic sand layer which is arranged below the planting layer and prevents moisture from permeating downwards, the planting sand layer can be backfilled to cover the super-hydrophobic sand layer.

The second method comprises the following steps: the spraying and stirring method includes spraying super-hydrophobic emulsion onto desert surface layer in controlled amount and controlled amount to make the emulsion penetrate downwards naturally for 2-20 cm, stirring sand with stable soil mixer, agricultural cultivator or rotary cultivator until all sand is soaked with the emulsion, spraying emulsion with the spraying device, stirring with the stirrer and other machines until all sand is soaked with the emulsion, and air drying naturally. And as a super-hydrophobic sand layer which is arranged below the planting layer and prevents moisture from permeating downwards, the planting sand layer needs to be backfilled to cover the super-hydrophobic sand layer.

The third method comprises the following steps: centralized processing method, building super-hydrophobic sand preparation factory near desert, mixing sand and emulsion in the factory, transporting the sand to desert area, spreading layer, and drying. The spread super-hydrophobic sand layer can be used as a super-hydrophobic sand layer below the planting layer for preventing moisture from permeating downwards, and can also be used as a super-hydrophobic sand layer above the planting sand layer for inhibiting moisture from evaporating.

The test result of the super-hydrophobic sand used for water retention and evaporation slowing of the desert surface is as follows:

the test process comprises the following steps: and the four ABCD containers are filled with the same amount of common sand and water, the surfaces of the C and D containers are covered with a layer of super-hydrophobic sand with the thickness of 1 cm, then the super-hydrophobic sand is placed into a 60-degree oven, the total weight is periodically tested, and the volatilized water is measured and calculated.

As a result: after 24 hours, 90% of the moisture in the a and B vessels had evaporated, while only 25% of the moisture in the C and D vessels had evaporated, so that the moisture in conventional sand evaporated 3.6 times faster than the moisture in the super-hydrophobic sand layer.

And (4) conclusion: under the same condition, the super-hydrophobic sand layer can well inhibit water evaporation after being covered with the super-hydrophobic sand layer, so that the water-retaining effect is achieved, and meanwhile, the super-hydrophobic sand layer has the functions of ventilation and heat insulation. In addition, when the water content in the sand is low and the temperature is low (the internal temperature of the sand is less than 60 ℃) (which is the more common condition in desert planting), the evaporation speed of the water in the common sand which is not covered with the super-hydrophobic sand is relatively higher, the water is relatively slower to cover, and the water retention effect is relatively better.

Experiment 1, 0.01% strength superhydrophobic emulsion treated river sand (0.001% effective active on sand);

10 kg of river sand and 1 kg of super-hydrophobic emulsion with the concentration of 0.01 percent are fully and uniformly mixed until all sand grains are soaked by the emulsion, and then the mixture is dried for 10 hours at the temperature of 80 ℃ to form hydrophobic sand, and the contact angle of water drops is more than 90 degrees.

A impermeability test;

the method comprises the steps of forming a plurality of holes in the bottom of a transparent barrel (glass or plastic) with the diameter of 5-10 cm and the height of 90 cm, covering the holes with gauze or cotton to prevent sand from leaking out, adding super-hydrophobic sand above the gauze to the thickness of 5 cm, vibrating, leveling, adding common sand to the thickness of 80 cm, and vibrating and leveling in the same way. And slowly adding water from the upper part until all the common sand is soaked completely, wherein the water level is 1 cm higher than the common sand layer, the added water is remained on the surface of the super-hydrophobic sand layer and cannot enter the super-hydrophobic sand layer, the super-hydrophobic sand still keeps the color of dry sand, and the common sand becomes the color of wet sand. The top of the tube was covered with a beaker to slow down the evaporation of water. The prepared test bucket was kept still for 1-10 months and observed for water seepage at the bottom or for changes in the dry/wet watermark margin between the two sand interfaces. If the water level is reduced during the retention period, a proper amount of water can be added for supplement. And (4) observing results: water seepage was observed at the bottom at 1 month.

Experiment 2, 0.01% strength superhydrophobic emulsion treated sea sand (0.001% effective active on sand);

fully and uniformly mixing 10 kg of sea sand and 1 kg of 0.01% super-hydrophobic emulsion until all sand grains are soaked by the emulsion, and then drying at the temperature of 80 ℃ for 10 hours to form hydrophobic sand, wherein the contact angle of water drops is more than 90 degrees.

A impermeability test;

a transparent barrel (glass or plastic) with the diameter of 5-10 cm and the height of 90 cm, a plurality of holes are formed at the bottom, then gauze is used for covering the holes, super-hydrophobic sand is added above the gauze to the thickness of 5 cm, the mixture is vibrated to be flat, finally common sand is added to the thickness of 80 cm, and the mixture is vibrated to be flat. And slowly adding water from the upper part until all the common sand is soaked completely, wherein the water level is 1 cm higher than the common sand layer, the added water is remained on the surface of the super-hydrophobic sand layer and cannot enter the super-hydrophobic sand layer, the super-hydrophobic sand still keeps the color of dry sand, and the common sand becomes the color of wet sand. The top of the tube was covered with a beaker to slow down the evaporation of water. The prepared test tube was kept still for 1-10 months and observed for water seepage at the bottom or for changes in the dry/wet watermark margin between the two sand interfaces. If the water level is reduced during the retention period, a proper amount of water can be added for supplement. And (4) observing results: the water seepage phenomenon appears at the bottom in 1 month.

Experiment 3;

0.1% strength superhydrophobic emulsion treated river sand (0.01% active on sand);

fully and uniformly mixing 10 kg of river sand and 1 kg of super-hydrophobic emulsion with the concentration of 0.1% until all sand grains are soaked by the emulsion, and then drying at the temperature of 80 ℃ for 10 hours to form the super-hydrophobic sand, wherein the contact angle of water drops can reach 120 degrees.

A impermeability test;

a transparent barrel (glass or plastic) with the diameter of 5-10 cm and the height of 90 cm, a plurality of holes are formed at the bottom, then gauze is used for covering the holes, super-hydrophobic sand is added above the gauze to the thickness of 5 cm, the mixture is vibrated to be flat, finally common sand is added to the thickness of 80 cm, and the mixture is vibrated to be flat. And slowly adding water from the upper part until all the common sand is soaked completely, wherein the water level is 1 cm higher than the common sand layer, the added water is remained on the surface of the super-hydrophobic sand layer and cannot enter the super-hydrophobic sand layer, the super-hydrophobic sand still keeps the color of dry sand, and the common sand becomes the color of wet sand. The top of the tube was covered with a beaker to slow down the evaporation of water. The prepared test tube was kept still for 1-10 months and observed for water seepage at the bottom or for changes in the dry/wet watermark margin between the two sand interfaces. If the water level is reduced during the retention period, a proper amount of water can be added for supplement. And (4) observing results: water seepage was observed at the bottom at 2 months.

Experiment 4;

1% strength superhydrophobic emulsion treated yellow sand (0.1% effective active on sand);

100 kg of yellow sand and 10 kg of super-hydrophobic emulsion with the concentration of 1% are fully and uniformly mixed until all sand grains are soaked by the emulsion, the super-hydrophobic sand is formed after natural airing, and the contact angle of water drops can reach 140 degrees.

A impermeability test;

a transparent barrel (glass or plastic) with the diameter of 5-10 cm and the height of 90 cm, a plurality of holes are formed at the bottom, then gauze is used for covering the holes, super-hydrophobic sand is added above the gauze to the thickness of 5 cm, the mixture is vibrated to be flat, finally common sand is added to the thickness of 80 cm, and the mixture is vibrated to be flat. And slowly adding water from the upper part until all the common sand is soaked completely, wherein the water level is 1 cm higher than the common sand layer, the added water is remained on the surface of the super-hydrophobic sand layer and cannot enter the super-hydrophobic sand layer, the super-hydrophobic sand still keeps the color of dry sand, and the common sand becomes the color of wet sand. The top of the tube was covered with a beaker to slow down the evaporation of water. The prepared test tube was left standing for 10 months and observed for water seepage at the bottom or changes in the dry/wet water mark boundary between the two sand interfaces. If the water level is reduced during the retention period, a proper amount of water can be added for supplement. And (4) observing results: the bottom of the sand layer is free from water seepage within 5 months, the dry/wet water mark boundary between the two sand layers is not obviously changed, water does not enter the super-hydrophobic sand layer, and the water is still prevented above the super-hydrophobic sand layer.

Experiment 5;

2% strength of super-hydrophobic emulsion treated desert sand (0.2% active on sand content);

fully and uniformly mixing 100 kg of desert sand and 10 kg of super-hydrophobic emulsion with the concentration of 2% until all sand grains are soaked by the emulsion, and naturally drying to form the super-hydrophobic sand, wherein the contact angle of water drops can reach 140 degrees.

A impermeability test;

a transparent barrel (glass or plastic) with the diameter of 5-10 cm and the height of 90 cm, a plurality of holes are formed at the bottom, then gauze is used for covering the holes, super-hydrophobic sand is added above the gauze to the thickness of 5 cm, the mixture is vibrated to be flat, finally common sand is added to the thickness of 80 cm, and the mixture is vibrated to be flat. And slowly adding water from the upper part until all the common sand is soaked completely, wherein the water level is 1 cm higher than the common sand layer, the added water is remained on the surface of the super-hydrophobic sand layer and cannot enter the super-hydrophobic sand layer, the super-hydrophobic sand still keeps the color of dry sand, and the common sand becomes the color of wet sand. The top of the tube was covered with a beaker to slow down the evaporation of water. The prepared test tube was left standing for 10 months and observed for water seepage at the bottom or changes in the dry/wet water mark boundary between the two sand interfaces. If the water level is reduced during the retention period, a proper amount of water can be added for supplement. And (4) observing results: the bottom of the sand layer is free from water seepage within 5 months, the dry/wet water mark boundary between the two sand layers is not obviously changed, water does not enter the super-hydrophobic sand layer, and the water is still prevented above the super-hydrophobic sand layer.

Test 6, desert sand treated with a super hydrophobic emulsion at 8% concentration (0.8% active on sand content);

fully and uniformly mixing 100 kg of desert sand and 10 kg of super-hydrophobic emulsion with the concentration of 8% until all sand grains are soaked by the emulsion, and naturally drying to form the super-hydrophobic sand, wherein the contact angle of water drops can reach 150 degrees.

And (3) impermeability test:

a transparent barrel (glass or plastic) with the diameter of 5-10 cm and the height of 90 cm, a plurality of holes are formed at the bottom, then gauze is used for covering the holes, super-hydrophobic sand is added above the gauze to the thickness of 5 cm, the mixture is vibrated to be flat, finally common sand is added to the thickness of 80 cm, and the mixture is vibrated to be flat. And slowly adding water from the upper part until all the common sand is soaked completely, wherein the water level is 1 cm higher than the common sand layer, the added water is remained on the surface of the super-hydrophobic sand layer and cannot enter the super-hydrophobic sand layer, the super-hydrophobic sand still keeps the color of dry sand, and the common sand becomes the color of wet sand. The top of the tube was covered with a beaker to slow down the evaporation of water. The prepared test tube was left standing for 10 months and observed for water seepage at the bottom or changes in the dry/wet water mark boundary between the two sand interfaces. If the water level is reduced during the retention period, a proper amount of water can be added for supplement. And (4) observing results: the bottom of the sand layer is not seeped within 10 months, the dry/wet water mark boundary between the two sand layers is not obviously changed, water does not enter the super-hydrophobic sand layer, and the water is still prevented above the super-hydrophobic sand layer.

Test 7, super-hydrophobic sand layer test in which the surface layer inhibits water evaporation;

the test process comprises the following steps: four same containers of ABCD are filled with the same amount of sand and water, a layer of super-hydrophobic sand layer with the thickness of 1 cm is added on the surface of the water-containing sand of the containers C and D, then the containers are put into an oven with the temperature of 60 ℃ for evaporation, the total weight is periodically tested, and the volatilized water content is calculated.

Referring to fig. 2, results: after 24 hours, 90% of the moisture in the a and B vessels had evaporated, while only 25% of the moisture in the C and D vessels had evaporated, so that the moisture in conventional sand evaporated 3.6 times faster than the moisture in the super-hydrophobic sand layer.

Moisture evaporation rates of a and B without super-hydrophobic sand coverage were 3.6 times faster than C and D with coverage.

After 24 hours, the moisture content in A and B had evaporated by 90%, while C and D only had evaporated by 25%

And (4) conclusion: under the same condition, the super-hydrophobic sand layer can well inhibit water evaporation after being covered with the super-hydrophobic sand layer, so that the water-retaining effect is achieved, and meanwhile, the super-hydrophobic sand layer has the functions of ventilation and heat insulation. In addition, when the water content in the sand is low and the temperature is low (the internal temperature of the sand is less than 60 ℃) (which is the more common condition in desert planting), the evaporation speed of the water in the common sand which is not covered with the super-hydrophobic sand is relatively higher, the water is relatively slower to cover, and the water retention effect is relatively better.