A hydrophilic and hydrophobic integrated membrane material for seawater desalination and a preparation method thereof

Abstract

The invention discloses a kind of hydrophilic and hydrophobic integrated membrane material and preparation method thereof for desalination of seawater, a hydrophilic solution with a concentration of 0.1 10 mol / L is coated on one side of substrate to obtain a hydrophilic coating;a hydrophobic solution with a concentration of 0.1 10 mol / L is coated on the other side of substrate to obtain a hydrophobic coating;the substrate coated with the coating is placed in a plasma reactor, a carrier gas is passed through, and a power supply parameter is adjusted to trigger a discharge to obtain a desalination membrane material;the edge of the desalination membrane material is subsequently subjected to water isolation treatment. A kind of hydrophilic and hydrophobic integrated membrane material and preparation method thereof for desalination of seawater disclosed by the present invention, by coating on the surface of the material, plasma modification technology is then utilized to prepare a desalination membrane material driven by solar energy, integrating hydrophilic and hydrophobic characteristics in different sides, with antifouling property, efficient desalination can be carried out, and fresh water output is increased.

Description

Technical Field

[0001] The present invention relates to the field of seawater desalination membrane materials, and in particular to a hydrophilic-hydrophobic integrated membrane material for seawater desalination and a preparation method thereof. Background Art

[0002] Water, a vital natural resource on Earth, is an indispensable material foundation for human survival and development. Despite Earth's vast water resources, freshwater accounts for only 2.5%, and only 0.26% of them are actually available for human use. According to the World Water Development Report, global water use has increased sixfold compared to the previous century. With increasing water pollution and the deterioration of the aquatic environment, more than a quarter of the world's population now faces severe water shortages. Driven by population growth and industrialization, and based on current water consumption trends, the freshwater supply shortage is projected to approach 40% by 2030. At the same time, people are increasingly aware of the broad social and ecological benefits that adequate water resources can bring, including economic vitality, public health, national security, and ecosystem health. This awareness is driving the search for technological solutions to address water scarcity. Drinkable freshwater, a natural resource essential for human survival, is facing severe shortages. Desalination is becoming a key approach to obtaining freshwater.

[0003] Currently used desalination methods, such as thermal and membrane processes, consume fossil energy and produce significant amounts of greenhouse gases. Compared to traditional fossil fuels, solar energy, as a sustainable, green energy source, can provide a new energy source for desalination. Solar evaporation desalination, a technology that directly utilizes solar energy to distill and purify water, is gaining widespread attention.

[0004] Currently, the main membranes for solar-driven seawater desalination include solar reverse osmosis membranes (SROD) and solar distillation membranes (SDM). The manufacturing processes of these materials are relatively complex and time-consuming, and a large amount of chemical reagents are inevitably required during the preparation process, including some toxic and harmful reagents, which will have adverse effects on the environment and the health of the preparers.

[0005] At the same time, in the process of using solar-driven membrane materials for seawater desalination, there are still many application technical problems with the membrane materials, such as: poor solar absorption rate, which leads to low efficiency in converting solar energy into thermal energy; less pore distribution inside the membrane material and complex and tortuous pore channels, which are not conducive to the transmission of water; long-term application of salt crystallization on the surface of the membrane material, which will increase light reflection and hinder the water transport channel of the membrane, resulting in a gradual decrease in evaporation rate and low steam flux.

[0006] In addition, with the rapid growth of population and increasingly serious water pollution, such as the use of large agricultural machinery leading to waste oil leakage, and dye wastewater pollution generated by printing and dyeing factories, the main components of which are emulsified oil and organic pollutants, the seawater contains more oil, dyes and other pollution sources. The presence of oil pollution reduces the efficiency of seawater desalination. Summary of the Invention

[0007] In response to the problem of poor efficiency of seawater desalination due to contamination by pollutants such as oil in the existing technology, the purpose of the present invention is to provide a hydrophilic-hydrophobic integrated membrane material for seawater desalination and a preparation method thereof. By coating the surface of the material and then using plasma modification technology to prepare a seawater desalination membrane material driven by solar energy, which combines hydrophilic and hydrophobic properties on different sides, it has anti-fouling properties, can carry out efficient seawater desalination, and increase freshwater production.

[0008] To achieve the above object, the present invention provides the following technical solution: a method for preparing a hydrophilic-hydrophobic integrated membrane material for seawater desalination, comprising the following steps:

[0009] S1: coating a 0.1-10 mol / L aqueous solution on one side of the substrate to obtain a hydrophilic coating; coating a 0.1-10 mol / L aqueous solution on the other side of the substrate to obtain a hydrophobic coating;

[0010] S2: placing the substrate coated in step S1 in a plasma reactor, introducing a carrier gas, adjusting the power supply parameters to induce discharge, with a discharge voltage of 12 kV-30 kV and a discharge frequency of 50 Hz-2.45 GHz. After a discharge treatment of 5-20 minutes, a seawater desalination membrane material can be obtained;

[0011] S3: performing water-isolating treatment on the edge of the seawater desalination membrane material obtained in step S2.

[0012] Furthermore, the discharge voltage is 12kV-30kV, the discharge frequency is 50Hz-2.45GHz, the microwave power supply discharge power is 50W-500W, and the discharge time is 5-20min.

[0013] Preferably, the discharge voltage is 12 kV, 15 kV or 20 kV; the discharge frequency is 50 Hz, 500 Hz, 1 kHz or 2 kHz; the microwave power is 100 W or 120 W, and the plasma modification time is 5 min, 10 min or 15 min.

[0014] Furthermore, in step S1, the substrate is selected from biomass materials or materials synthesized physically, chemically, or physicochemically.

[0015] Furthermore, in step S1, the substrate is selected from biomass materials, and the biomass materials are selected from wood, sugarcane or straw; preferably, the substrate is selected from wood.

[0016] Furthermore, in step S1, the hydrophobic solution is selected from at least one of acrylamide, tetramethoxysilane, hexamethyldisilazane, polypyrrole, acrylonitrile, ethyleneimine and the like;

[0017] The hydrophilic solution is selected from at least one of sodium silicate, sodium alginate, sodium alkyl sulfonate, sodium fatty alcohol ether sulfate and the like.

[0018] Furthermore, the hydrophobic solution comprises acrylamide and hexamethyldisilazane in a weight ratio of 1:3.

[0019] Furthermore, the hydrophilic solution comprises sodium silicate and sodium alginate in a weight ratio of 1:2.

[0020] Furthermore, in step S1, the coating method is spraying and / or brushing;

[0021] The spraying parameters were: nozzle flow rate 0.5 mL / s, spraying time 1-2 s;

[0022] The brushing parameters are: brushing 1-5 times.

[0023] Furthermore, in step S2, the plasma reactor is selected from a dielectric barrier discharge plasma reactor, a microwave discharge plasma reactor or a jet discharge plasma reactor.

[0024] Furthermore, in step S1, the carrier gas is selected from at least one of air, nitrogen, oxygen, hydrogen or argon, and the carrier gas flow rate is 50-200 mL / min; preferably, the carrier gas is nitrogen.

[0025] Furthermore, in step S3, the water-proofing treatment method is: coating with silicone or adhering an outer layer of metal foil; preferably, the water-proofing method adopts coating with silicone, and the coating thickness is 0.1-0.01cm, and more preferably, the coating thickness of silicone is 0.02cm.

[0026] A hydrophilic and hydrophobic integrated membrane material for seawater desalination is prepared by adopting the method.

[0027] In summary, the present invention has the following beneficial effects:

[0028] First, this application applies different coatings on the surface of the substrate, and then uses plasma to modify the coated substrate through plasma. The prepared hydrophilic and hydrophobic integrated membrane material can directly absorb solar energy, convert solar energy into heat energy, and desalinate seawater. The hydrophilic effect of the lower hydrophilic surface ensures the upward supply of water from below; its hydrophilic properties can prevent oily pollutants in the water from blocking the water channels, preventing pollutants from being transported with water to the upper surface for evaporation and contaminating freshwater products; the abundant pores with low torsion in the material body ensure that water can be transported to the upper surface, balancing the salinity difference between the material and the water body; the hydrophobic upper surface has a strong light absorption effect, which solves the problem of low light energy utilization rate of traditional solar interface evaporation materials, thereby accelerating the escape of water molecules and increasing the evaporation rate. The hydrophobic properties and edge treatment effectively prevent the formation of crystalline salts. The solar desalination material prepared by the present invention using a coating and then based on plasma modification technology has a strong light absorption capacity, a rich pore structure, anti-fouling, salt corrosion resistance, and a high evaporation flux;

[0029] Second, the hydrophilic and hydrophobic integrated membrane material prepared by the coating and plasma modification technology described in the present invention overcomes the shortcomings of traditional seawater desalination materials that use large amounts of chemicals for interfacial evaporation using solar energy, such as the complex preparation process, long time consumption, poor anti-fouling, low work efficiency, and short lifespan. In actual seawater desalination applications, its powerful photothermal effect enables an evaporation rate of up to 2.3137 kg·m -2 h -1 , solar-steam efficiency is as high as 98%;

[0030] Third, the material prepared by the method of the present application has a multi-porous structure with low torsion, and the surfaces on both sides exhibit different hydrophilic and hydrophobic properties. The hydrophilic side can quickly transport water to the evaporation interface, increasing the evaporation rate. The evaporation interface is hydrophobic, which can reduce the interaction between water molecules and the interface and prevent salt crystallization.

[0031] Fourth, the material prepared by the method of the present application has an anti-fouling effect and can be applied to polluted water bodies. The evaporation rate in polluted water bodies is not affected, and it has a highly effective purification effect on oily wastewater and dye wastewater.

[0032] Fifth, if the material needs to be discarded, since the main part of the material prepared by the preparation method of the present application is biomass, a variety of treatment technologies can be selected, and the harm to the environment is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0034] Figure 1 Schematic diagram of the jet discharge device structure.

[0035] Figure 2 Schematic diagram of the dielectric barrier discharge device structure.

[0036] Figure 3 Schematic diagram of the microwave discharge device structure.

[0037] Figure 4 This is a schematic diagram of the needle plate discharge device structure.

[0038] Figure 5 This is a scanning electron microscope characterization image of the low-torsion channel of the longitudinal section of the material prepared in Example 4.

[0039] Figure 6 Comparison of the salinity of freshwater products before and after desalination treatment.

[0040] Figure 7 The following are comparison photos of salt crystallization on the illuminated surface of Example 1, Example 4 and Comparative Example 4 after continuous operation in simulated salt water for 14 hours.

[0041] Figure 8 The following are the ultraviolet absorption spectra of the methylene blue solution and the obtained fresh water, as well as the comparison photos of the water samples.

[0042] Figure 9 Microscope views of the oil-water mixture and the resulting fresh water, as well as comparative photos of the water samples. DETAILED DESCRIPTION

[0043] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be combined with the appended drawings of the embodiments of the present invention. Figure 1-9 The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0044] Unless otherwise specified, wt% refers to percentage by weight. All reagents and instruments used without manufacturer indicated are commercially available conventional reagents.

[0045] Preparation Example

[0046] Preparation Example 1 of Hydrophilic Aqueous Solution

[0047] A 1 mol / L sodium silicate solution and a 1 mol / L sodium alginate solution were uniformly mixed in a volume ratio of 1:2 to obtain a hydrophilic solution-1.

[0048] Preparation Example 2 of Hydrophilic Aqueous Solution

[0049] A 1 mol / L sodium silicate solution and a 1 mol / L sodium alginate solution were uniformly mixed in a volume ratio of 1:3 to obtain a hydrophilic solution-2.

[0050] Preparation Example 3 of Hydrophilic Aqueous Solution

[0051] A 1 mol / L sodium silicate solution and a 1 mol / L sodium alginate solution were uniformly mixed in a volume ratio of 2:3 to obtain a hydrophilic solution-3.

[0052] Preparation Example 4 of Hydrophilic Aqueous Solution

[0053] A 1 mol / L sodium silicate solution, a 1 mol / L sodium alginate solution, and a 1 mol / L sodium alkyl sulfonate solution were uniformly mixed in a volume ratio of 1:1:1 to obtain a hydrophilic solution-4.

[0054] Preparation Example 1 of Hydrophobic Solution

[0055] An acrylamide solution with a concentration of 1 mol / L and a hexamethyldisilazane solution with a concentration of 1 mol / L were mixed uniformly in a volume ratio of 1:2 to obtain a hydrophobic solution-1.

[0056] Preparation Example 2 of Hydrophobic Solution

[0057] An acrylamide solution with a concentration of 1 mol / L and a hexamethyldisilazane solution with a concentration of 1 mol / L were mixed uniformly in a volume ratio of 1:3 to obtain a hydrophobic solution-2.

[0058] Preparation Example 3 of Hydrophobic Solution

[0059] An acrylamide solution with a concentration of 1 mol / L, a hexamethyldisilazane solution with a concentration of 1 mol / L, and an ethyleneimine solution with a concentration of 1 mol / L were uniformly mixed in a volume ratio of 1:1:1 to obtain a hydrophobic solution-3.

[0060] Example

[0061] Example 1

[0062] A method for preparing a hydrophilic-hydrophobic integrated membrane material comprises the following steps:

[0063] S1: Apply a sodium silicate solution with a concentration of 0.5 mol / L to one side of a 3×3 cm dry wood slice twice. Apply an acrylamide solution with a concentration of 0.5 mol / L to the other side of the dry wood slice once and let it dry for 1 hour.

[0064] S2: The dried substrate was placed in a jet discharge plasma reactor, and nitrogen was introduced through the bottom pores of the jet discharge plasma reactor at a flow rate of 50 mL / min, a discharge voltage of 12 kV, a discharge frequency of 50 Hz, and a discharge time of 15 min to obtain a seawater desalination membrane material;

[0065] S3: Thinly coating silica gel on the longitudinal outer edge surface of the desalination membrane material for water-isolating treatment to obtain the target material;

[0066] Reference Figure 1 The jet discharge plasma reactor includes a power supply 1, a radio frequency electrode 2, an insulating material 3, a substrate 4, a jet plasma reaction zone 5, a ground electrode 6, a valve 7, a gas flow meter 8, a gas cylinder 9, and an experimental base 10.

[0067] Before use, connect the power supply to the discharge electrode, ground the ground electrode, and connect the gas cylinder device. When using, place the coated and dried substrate in the discharge device, introduce the carrier gas from the lower vent, control the carrier gas flow rate by the gas flow meter, start the power supply, adjust the relevant parameters, trigger the device to discharge, and perform plasma modification on the substrate.

[0068] Example 2

[0069] A method for preparing a hydrophilic-hydrophobic integrated membrane material comprises the following steps:

[0070] S1: Apply a hydrophobic solution 1 to one side of a 3×3 cm dry wood slice twice by brushing; apply a hydrophilic solution 1 to the other side of the dry wood slice once by brushing, and let it dry for 1 hour;

[0071] S2: The dried substrate was placed in a jet discharge plasma reactor, and nitrogen was introduced through the bottom pores of the jet discharge plasma reactor at a flow rate of 100 mL / min, a discharge voltage of 12 kV, a discharge frequency of 50 Hz, and a discharge time of 12 min to obtain a seawater desalination membrane material;

[0072] S3: Apply a thin layer of silica gel to the longitudinal outer edge surface of the seawater desalination membrane material for water-isolating treatment to obtain the target material.

[0073] Example 3

[0074] A method for preparing a hydrophilic-hydrophobic integrated membrane material comprises the following steps:

[0075] S1: Same as Example 2;

[0076] S2: The dried substrate was placed in a dielectric barrier discharge plasma reactor, and nitrogen was introduced through the bottom pores of the dielectric barrier discharge plasma reactor at a flow rate of 150 mL / min, a discharge voltage of 21 kV, a discharge frequency of 2 kHz, and a discharge time of 12 min to obtain a seawater desalination membrane material;

[0077] S3: Same as Example 2.

[0078] Reference Figure 2 The dielectric barrier discharge plasma reactor includes a power supply 1, a high voltage electrode 2, a ground electrode 3, a substrate 4, an upper vent 5, a lower vent 6, a valve 7, a gas flow meter 8, a gas cylinder 9, and a ground electrode 10.

[0079] Before use, connect the power supply to the discharge electrode, ground the ground electrode, and connect the gas cylinder device. When using, place the coated and dried substrate in the discharge device, introduce the carrier gas from the lower vent, control the carrier gas flow rate by the gas flow meter, start the power supply, adjust the relevant parameters, trigger the device to discharge, and perform plasma modification on the substrate.

[0080] Example 4

[0081] A method for preparing a hydrophilic-hydrophobic integrated membrane material comprises the following steps:

[0082] S1: Apply the hydrophobic solution-2 to one side of a 3×3 cm dry wood slice by brushing three times; apply the hydrophilic solution-1 to the other side of the dry wood slice by brushing three times and let it dry for 1 hour;

[0083] S2: Same as Example 3;

[0084] S3: Same as Example 3.

[0085] Example 5

[0086] A method for preparing a hydrophilic-hydrophobic integrated membrane material comprises the following steps:

[0087] S1: Apply the hydrophobic solution-3 to one side of a 3×3 cm dry wood slice by brushing three times; apply the hydrophilic solution-2 to the other side of the dry wood slice by brushing three times and let it dry for 1 hour;

[0088] S2: Same as Example 3;

[0089] S3: Same as Example 3.

[0090] Example 6

[0091] A method for preparing a hydrophilic-hydrophobic integrated membrane material comprises the following steps:

[0092] S1: Apply the hydrophobic solution -3 twice to one side of a 3×3 cm dry wood slice; apply the hydrophilic solution -2 once to the other side of the dry wood slice and let it dry for 1 hour.

[0093] S2: The dried substrate was placed in a microwave discharge plasma reactor, and nitrogen was introduced through the bottom pore of the microwave discharge plasma reactor at a flow rate of 150 mL / min, a discharge power of 100 W, a discharge frequency of 2.45 GHz, and a discharge time of 15 min to obtain a seawater desalination membrane material;

[0094] S3: Apply a thin layer of silica gel to the longitudinal outer edge surface of the seawater desalination membrane material for water-isolating treatment to obtain the target material.

[0095] Reference Figure 3 The microwave discharge plasma reactor includes: a power supply 1, a microwave reaction zone 2, an experimental base 3, a substrate 4, an upper air vent 5, a lower air vent 6, a valve 7, a gas flow meter 8 and a gas cylinder 9.

[0096] Before use, connect the power supply to the discharge electrode, ground the ground electrode, and connect the gas cylinder device. When using, place the coated and dried substrate in the discharge device, introduce the carrier gas from the lower vent, control the carrier gas flow rate by the gas flow meter, start the power supply, adjust the relevant parameters, trigger the device to discharge, and perform plasma modification on the substrate.

[0097] Example 7

[0098] A method for preparing a hydrophilic-hydrophobic integrated membrane material comprises the following steps:

[0099] S1: Apply a hydrophobic solution-2 to one side of a 3×3 cm dry wood slice by brushing three times; apply a hydrophilic solution-2 to the other side of the dry wood slice by brushing three times and let it dry for 1 hour;

[0100] S2: The difference from Example 6 is that the flow rate is 100 mL / min, the discharge power is 120 W, the discharge frequency is 2.45 GHz, and the discharge time is 12 min;

[0101] S3: Same as Example 6.

[0102] Example 8

[0103] A method for preparing a hydrophilic-hydrophobic integrated membrane material comprises the following steps:

[0104] S1: Apply a hydrophobic solution -4 to one side of a 3×3 cm dry wood slice by brushing 3 times; apply a hydrophilic solution -3 to the other side of the dry wood slice by brushing 3 times and let it dry for 1 hour;

[0105] S2: Place the dried substrate in a pin-plate discharge plasma reactor and introduce nitrogen gas through the bottom pores of the pin-plate discharge plasma reactor at a flow rate of 150 mL / min, a discharge voltage of 20 kV, a discharge frequency of 40 Hz, a pin-plate spacing of 10 mm, and a discharge time of 12 min.

[0106] S3: Apply a thin layer of silica gel to the longitudinal outer edge surface of the seawater desalination membrane material for water-isolating treatment to obtain the target material.

[0107] Reference Figure 4 The needle-plate discharge plasma reactor includes: a power supply 1, a needle electrode 2, an insulating material 3, a substrate 4, a plasma reaction zone 5, a ground electrode 6, a valve 7, a gas flow meter 8, and a gas cylinder 9.

[0108] Before use, connect the power supply to the discharge electrode, ground the ground electrode, and connect the gas cylinder device. When using, place the coated and dried substrate in the discharge device, introduce the carrier gas from the lower vent, control the carrier gas flow rate by the gas flow meter, start the power supply, adjust the relevant parameters, trigger the device to discharge, and perform plasma modification on the substrate.

[0109] Example 9

[0110] A method for preparing a hydrophilic-hydrophobic integrated membrane material comprises the following steps:

[0111] S1: Apply the hydrophobic solution-1 to one side of a 3×3 cm dry wood slice by brushing three times; apply the hydrophilic solution-2 to the other side of the dry wood slice by brushing three times and let it dry for 1 hour;

[0112] S2: The difference from Example 8 is that the flow rate is 100 mL / min, the discharge voltage is 30 kV, the discharge frequency is 20 Hz, and the needle plate spacing is 15 mm;

[0113] S3: Same as Example 8.

[0114] Comparative Example

[0115] Comparative Example 1

[0116] A method for preparing a hydrophilic-hydrophobic integrated membrane material comprises the following steps:

[0117] S1: Apply a sodium silicate solution with a concentration of 1 mol / L to one side of a 3×3 cm dry straw slice by brushing three times; apply an acrylamide solution with a concentration of 1 mol / L to the other side of the dry straw slice by brushing once, and let it dry for 1 hour;

[0118] S2: Place the dried substrate on each side above an alcohol lamp for 30 seconds to carbonize its surface to obtain the target film material.

[0119] Comparative Example 2

[0120] A method for preparing a hydrophilic-hydrophobic integrated membrane material comprises the following steps:

[0121] S1: Apply a polypyrrole solution with a concentration of 1 mol / L to one side of a 3×3 cm dry wood slice twice by brushing. Apply a tetramethoxysilane solution with a concentration of 1 mol / L to the other side of the dry wood slice twice by brushing and let it dry for 1 hour.

[0122] S2: Place the dried substrate in a furnace, heat it to about 105°C, then slowly raise the temperature to about 370°C. Stop the fire when the smoke output becomes smaller, and take it out when the furnace temperature cools to about 35°C to obtain the target material.

[0123] Comparative Example 3

[0124] S1: Apply a sodium alginate solution with a concentration of 1 mol / L to one side of a 3×3 cm dry wood slice twice by brushing. Apply an ethyleneimine solution with a concentration of 1 mol / L to the other side of the dry wood slice twice by brushing and let it dry for 1 hour.

[0125] S2: Place the dried substrate in a furnace, heat it to about 105°C, then slowly raise the temperature to about 370°C. Stop the fire when the smoke output becomes smaller, and take it out when the furnace temperature cools to about 35°C to obtain the target material.

[0126] Comparative Example 4

[0127] A method for preparing a hydrophilic-hydrophobic integrated membrane material comprises the following steps:

[0128] 3×3 cm dry wood slices were placed in a jet discharge device, and nitrogen was introduced from the bottom air hole at a flow rate of 100 mL / min, a discharge voltage of 15 kV, a discharge frequency of 500 Hz, and a discharge time of 12 min to obtain the target material.

[0129] Performance testing

[0130] Test Example 1

[0131] The interface evaporation rate, solar-steam efficiency and desalinated water salinity of the target materials prepared in Examples 1-9 and Comparative Examples 1-4 were tested in seawater.

[0132] 1. The target material was placed on the surface of a 3.5 wt% sodium chloride solution (equivalent to the average salinity of seawater) and the interfacial evaporation rate and solar-steam efficiency were tested for 1 h under one sun illumination. The test results are shown in Table 1.

[0133] The formula for calculating the interfacial evaporation rate is as follows:

[0134]

[0135] Where υ represents the interfacial evaporation rate, m2 represents the mass of the solution after illumination, m1 represents the mass of the solution before illumination, s represents the surface area of ​​the desalination membrane material receiving illumination, and t represents the illumination time.

[0136] The solar-steam efficiency calculation formula is as follows:

[0137]

[0138] Where η represents the solar-steam efficiency, m represents the steam generation rate after deducting the evaporation rate under dark field, and h lv represents the total enthalpy of steam generation, which includes sensible heat and phase change enthalpy, C opt represents optical density, and P represents the standard solar illuminance of one sun.

[0139] Table 1 Interface evaporation rate and solar-steam efficiency of target materials

[0140]

[0141]

[0142] Combining Examples 1-9, Comparative Examples 1-4 and Table 1, it can be seen that due to the water-isolating treatment, i.e., applying a thin layer of silica gel to the longitudinal outer edge surface of the desalination membrane material, the interfacial evaporation rate and the solar-steam efficiency are improved;

[0143] In combination with Examples 1-9, Comparative Examples 1 and 4 and Table 1, it can be seen that a combination of sodium silicate and sodium alginate is used as a hydrophilic coating, and a combination of acrylamide and hexamethylsiloxane is used as a hydrophobic coating. Since the hydrophilic coating can improve the surface wettability and surface free energy of poplar wood, the hydrophobic coating can introduce hydrophobic groups such as carbon double bond structures, silicon oxygen structures, etc., while enhancing the light-heat conversion ability, thereby improving the interfacial evaporation rate and solar energy-steam efficiency.

[0144] Combining Examples 3-5 and Table 1, it can be seen that as the amount of sodium alginate added increases, the interfacial evaporation rate and solar-steam efficiency are improved due to the increase in hydrophilic structures such as hydroxyl groups;

[0145] Combining Examples 3-5 and Table 1, it can be seen that as the amount of hydrophobic coating solution added increases, more hydrophobic medium is generated at the substrate interface during the treatment process. Properly enhancing the hydrophobic ability can stabilize or even enhance the light-to-heat conversion ability, but excessive deposition of hydrophobic medium may lead to pore blockage, resulting in a decrease in the interfacial evaporation rate and solar-steam efficiency.

[0146] In combination with Examples 1-9 and Table 1, it can be seen that by changing the discharge form, when a jet discharge plasma reactor is used, the jet plasma generation area is limited, resulting in poor uniformity of the substrate interface reaction; when a dielectric barrier discharge plasma reactor is used, the plasma is uniformly generated in the reactor, the degree of reaction of the plasma acting on the substrate interface is consistent, and the substrate interface is uniformly treated; when a microwave discharge plasma reactor is used, since the interface and interior of the substrate are non-metallic and the water content is very low, the degree of carbonization of the substrate interface is low, affecting the light-to-heat conversion capacity; when a needle-plate discharge plasma reactor is used, the plasma is generated between the needle-plate electrodes, resulting in poor uniformity of the substrate interface reaction; different plasma reactors result in different degrees of carbonization treatment of the substrate, which in turn affects the interface evaporation rate and solar-steam efficiency.

[0147] 2. Testing of desalinated water salinity

[0148] The conductivity was measured using a conductivity meter, and the salinity of the desalinated water was calculated based on the conductivity-salinity trend line equation. The test results are shown in Table 2.

[0149] The conductivity-salinity trend line equation is as follows:

[0150] y=13.961x+0.0079

[0151] Where y represents conductivity and x represents salinity.

[0152] Table 2 Salinity of desalinated water of target materials

[0153]

[0154] Combining Examples 1-9, Comparative Examples 1-4, and Table 2, it can be seen that selecting and applying appropriate coatings and treatment methods can impart desalination capabilities to the materials. Specifically, a combination of acrylamide and hexamethylsiloxane is used as a hydrophobic coating. Since acrylamide and hexamethylsiloxane can introduce hydrophobic groups such as carbon double bonds and silicon-oxygen structures, while enhancing the hydrophobicity of the evaporation interface, they block salt from reaching the evaporation interface, thereby providing the ability to remove salt. All plasma-treated coating materials exhibited strong desalination capabilities, with the salinity of the desalinated water at the same level, indicating that the plasma-prepared coating material exhibited superior desalination capabilities.

[0155] Test Example 2

[0156] The target materials prepared in Examples 1-9 and Comparative Examples 1-4 were tested for interfacial evaporation rate, solar-steam efficiency, and desalinated water salinity in seawater containing sewage;

[0157] A 10 ppm methylene blue solution was mixed with a 3.5% sodium chloride solution to simulate seawater containing sewage. The interfacial evaporation rate, solar-steam efficiency, and desalinated water salinity were tested using the same methods as in Test Example 1. The methylene blue removal rate was calculated based on the UV absorption spectra of the desalinated and raw water. The test results are shown in Table 3.

[0158] Table 3 Test results in seawater containing sewage (organic pollutants)

[0159]

[0160] In combination with Examples 1-9, Comparative Examples 1-4 and Table 3, it can be seen that the selection and suitable coating and treatment methods can enable the material to have the function of removing organic pollutants while achieving desalination. Among them, a combination of sodium silicate and sodium alginate is used as a hydrophilic coating, and a combination of acrylamide and hexamethylsiloxane is used as a hydrophobic coating. Since sodium silicate and sodium alginate can improve the surface wettability and surface free energy of poplar wood, acrylamide and hexamethylsiloxane can introduce hydrophobic groups such as carbon double bond structure, silicon oxygen structure, etc., while strengthening the evaporation ability of the evaporation interface, it can block organic pollutants from reaching the evaporation interface. Organic pollutants cannot reach the evaporation interface for evaporation, so the prepared materials have the ability to remove pollutants. According to data analysis, the prepared materials all have a strong ability to remove organic pollutants. It can be seen that the carbonized biomass material with biomass as the substrate and the addition of coating materials has a strong ability to remove organic pollutants while having desalination ability, and the best removal effect is the material using plasma as the preparation technology.

[0161] Test Example 3

[0162] The interface evaporation rate, solar-steam efficiency and desalinated water salinity of the target materials prepared in Examples 1-9 and Comparative Examples 1-4 were tested in high-salinity seawater.

[0163] A 10 wt % sodium chloride solution was used to simulate high-salinity seawater. The test methods for the interfacial evaporation rate, solar-steam efficiency, and desalinated water salinity were the same as those in Test Example 1. The test results are shown in Table 4.

[0164] Table 4 Test results of target materials in high salinity seawater

[0165]

[0166] Selecting and suitable coatings and treatment methods can enable the material to have the function of removing salt while achieving desalination. In the real environment, it is inevitable that high-salinity salt water needs to be purified. In combination with Examples 1-9, Comparative Examples 1-4 and Table 4, it can be seen that in the present invention, a combination of sodium silicate and sodium alginate is used as a hydrophilic coating, and a combination of acrylamide and hexamethylsiloxane is used as a hydrophobic coating. Since sodium silicate and sodium alginate can improve the surface wettability and surface free energy of poplar wood, acrylamide and hexamethylsiloxane can introduce hydrophobic groups such as carbon double bond structures and silicon oxygen structures. While strengthening the evaporation capacity of the evaporation interface, it effectively blocks salt from reaching the evaporation interface. Even in high-salinity salt water, it also has the ability to efficiently remove salt. In the plasma-treated coating materials, all have strong desalination capabilities, and the salinity of desalinated water is of the same order of magnitude. It can be seen that the coating materials prepared by plasma have better desalination capabilities in high-salinity salt water.

[0167] Test Example 4

[0168] The target materials prepared in Examples 1-9 and Comparative Examples 1-4 were tested for interfacial evaporation rate, solar-steam efficiency, and desalinated water salinity in seawater simulating oily wastewater;

[0169] 1g of silicone oil and 0.1g of Span 80 were added to 100mL of deionized water. A stable oil-water mixture was prepared by ultrasonication to simulate oily wastewater. This mixture was then mixed with a 3.5% sodium chloride solution to simulate the seawater containing the oily wastewater. The interfacial evaporation rate, solar-steam efficiency, and desalinated water salinity were tested using the same methods as in Test Example 1. Oil removal was measured by microscopically measuring the ratio of the number of oil droplets in the desalinated water to the total number of oil droplets in the oiled water. The test results are shown in Table 5.

[0170] Table 5 Test results in seawater containing sewage (oil)

[0171] Test items Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 <![CDATA[Interface evaporation rate (kg·m -2 h -1 )]]> 1.9965 2.2236 2.2564 2.3201 2.1596 2.0101 2.2195 Solar-steam efficiency (%) 75 90 93 97 86 76 94 Desalination water salinity (%) 0.0041 0.0037 0.0031 0.0021 0.0035 0.0041 0.0058 Oil removal (%) 90 92 98 100％ 95 94 96 Test items Example 8 Example 9 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 <![CDATA[Interface evaporation rate (kg·m -2 h -1 )]]> 2.1245 1.8965 1.4765 1.8102 1.7654 1.5234 Solar-steam efficiency (%) 84 68 38 67 57 39 Desalination water salinity (%) 0.0037 0.0095 0.0501 0.0254 0.0402 0.0384 Oil removal status 97 89 85 92 90 89

[0172] Combining Examples 1-9, Comparative Examples 1-4, and Table 5, it can be seen that a combination of sodium silicate and sodium alginate is used as a hydrophilic coating, and a combination of acrylamide and hexamethylsiloxane is used as a hydrophobic coating. Since the hydrophilic coating can improve the surface wettability and surface free energy of poplar wood, and the hydrophobic coating can introduce hydrophobic groups such as carbon double bond structures and silicon oxygen structures, the hydrophilic layer not only improves the water transport capacity, but also plays an oil-isolating role. While strengthening the evaporation capacity of the evaporation interface, it can block oil from reaching the evaporation interface, preventing oil from evaporating at the evaporation interface. Therefore, the prepared material has the ability to remove oil from salt water. According to data analysis, the prepared materials all have a strong ability to remove oil from salt water. It can be seen that the carbonized biomass material with biomass as the base material and the addition of the coating material has a strong ability to remove organic pollutants while having desalination capacity. Among them, the best removal effect is the material prepared using plasma as the preparation technology.

[0173] In summary, discharge conditions, such as different reagents, number of coatings, discharge form, and its parameters, significantly influence the properties of the prepared materials. This can be reflected in their ability to desalinate and remove oil-laden seawater. Generally speaking, hydrophilic materials are oleophobic. The type, mixing ratio, concentration, and number of coatings applied to the hydrophilic side affect water transport and oil removal. Failure to achieve optimal water absorption reduces the interfacial evaporation rate and affects the equilibrium between the salinity of water in the material and that of the bulk seawater, thereby impacting the material's ability to block oil from seawater. The type, mixing ratio, concentration, and number of coatings applied to the hydrophobic side affect salt deposition on the material surface. Failure to achieve optimal hydrophilic-hydrophobic properties reduces the interfacial evaporation rate, solar-to-steam efficiency, and results in higher salinity in the desalinated water. Discharge conditions, such as the discharge form and its parameters, influence the energy applied to the biomass. Too little energy applied to the biomass results in incomplete carbonization, affecting the pore distribution per unit area and light absorption properties. However, if too much energy is applied to the biomass, it will lead to excessive carbonization, destroy the original pores and coating structure, and affect the interface evaporation rate, solar-steam efficiency, salt balance process, salt deposition resistance and oil barrier performance of the prepared material, thereby affecting the salinity of the desalinated water and the amount of oil contained therein during the solar desalination process of the prepared material.

[0174] In summary, compared with the existing technology: the new hydrophilic-hydrophobic integrated seawater desalination material of the present invention has the ability to efficiently absorb solar energy and convert thermal energy. The different hydrophilic and hydrophobic properties on both sides of the material can quickly and efficiently desalinate seawater, increase freshwater production, have anti-fouling properties, and have a simple preparation process, short time consumption, long product life, and low cost.

[0175] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a hydrophilic-hydrophobic integrated membrane material for seawater desalination, characterized in that: The steps include: S1: coating a 0.1-10 mol / L aqueous solution on one side of the substrate to obtain a hydrophilic coating; coating a 0.1-10 mol / L aqueous solution on the other side of the substrate to obtain a hydrophobic coating; S2: placing the substrate coated in step S1 in a plasma reactor, introducing a carrier gas, adjusting the power supply parameters to induce discharge, with a discharge voltage of 12 kV-30 kV and a discharge frequency of 50 Hz-2.45 GHz. After a discharge treatment of 5-20 minutes, a seawater desalination membrane material can be obtained; S3: performing water-isolating treatment on the edge of the seawater desalination membrane material obtained in step S2.

2. The method for preparing a hydrophilic-hydrophobic integrated membrane material for seawater desalination according to claim 1, characterized in that: In step S1, the substrate is selected from biomass materials or materials synthesized physically, chemically, or physicochemically.

3. The method for preparing a hydrophilic-hydrophobic integrated membrane material for seawater desalination according to claim 2, characterized in that: In step S1 , the substrate is selected from a biomass material, and the biomass material is selected from wood, sugar cane or straw.

4. The method for preparing a hydrophilic-hydrophobic integrated membrane material for seawater desalination according to claim 1, characterized in that: In step S1, the hydrophobic solution is selected from at least one of tetramethoxysilane, hexamethyldisilazane, polypyrrole, acrylonitrile, and ethyleneimine; The hydrophilic solution is selected from at least one of sodium silicate, sodium alginate, sodium alkyl sulfonate, and sodium fatty alcohol ether sulfate.

5. The method for preparing a hydrophilic-hydrophobic integrated membrane material for seawater desalination according to claim 4, characterized in that: The hydrophilic solution includes sodium silicate and sodium alginate in a weight ratio of 1:

2.

6. The method for preparing a hydrophilic-hydrophobic integrated membrane material for seawater desalination according to claim 1, characterized in that: In step S1, the coating method is spraying and / or brushing; The spraying parameters were: nozzle flow rate 0.5 mL / s, spraying time 1-2 s; The brushing parameters are: brushing 1-5 times.

7. The method for preparing a hydrophilic-hydrophobic integrated membrane material for seawater desalination according to claim 1, characterized in that: In step S2, the plasma reactor is selected from a dielectric barrier discharge plasma reactor, a microwave discharge plasma reactor or a jet discharge plasma reactor.

8. The method for preparing a hydrophilic-hydrophobic integrated membrane material for seawater desalination according to claim 1, characterized in that: In step S1, the carrier gas is selected from at least one of air, nitrogen, oxygen, hydrogen or argon, and the carrier gas flow rate is 50-200 mL / min.

9. A hydrophilic and hydrophobic integrated membrane material for seawater desalination, characterized in that: The method according to any one of claims 1 to 8 is used to prepare the product.

Images