CN108654579B - Preparation method of sodium alginate/typha orientalis/graphene oxide composite aerogel - Google Patents
Preparation method of sodium alginate/typha orientalis/graphene oxide composite aerogel Download PDFInfo
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Abstract
The invention relates to a preparation method of sodium alginate/typha orientalis/graphene oxide composite aerogel, belonging to the technical field of preparation of biomass-based functional materials; the method comprises the following specific steps: mixing sodium alginate powder and typha orientalis fiber, adding the mixture into the graphene oxide dispersion liquid, and stirring to obtain a uniform mixed solution; freeze-drying by two-way freeze casting to obtain uncrosslinked composite aerogel, soaking in CaCl2And performing secondary freeze drying on the mixed solution of ethanol and water to obtain the calcium ion crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel. According to the three-dimensional parallel lamellar structure, the parallel lamellar is connected with each other through honeycomb holes, so that the three-dimensional parallel lamellar structure has excellent underwater super-oleophobic property; and after the composite aerogel and the filtering instrument are assembled, insoluble oil and water-soluble dye can be synchronously removed, so that the composite aerogel and the filtering instrument have good application value and wide market prospect.
Description
Technical Field
The invention relates to a preparation method of sodium alginate/typha orientalis/graphene oxide composite aerogel, and belongs to the technical field of preparation of biomass-based functional materials.
Background
Due to the increasing emission of a large amount of water-soluble organic pollutants such as oily sewage and dyes year by year, a plurality of organic pollutants coexist in the wastewater, and how to synchronously remove the organic pollutants in the wastewater becomes a focus of attention worldwide. The rapid and efficient separation of the oil-water mixture and the removal of the water-soluble organic pollutants have very important practical significance for the treatment and protection of the ecological environment and the recycling of renewable resources. However, conventional organic pollutant removal methods, such as by combustion, mechanical treatment, addition of dispersants, biological treatment, and the like. Some have low removal efficiency, some easily cause secondary pollution due to adding chemical agents, and other have high energy consumption and high cost. Therefore, research on novel green materials, methods and technologies for synchronously removing organic pollutants has become a hot point in the field of functional materials.
The aerogel is a solid material with high porosity, has lower density and a three-dimensional network structure, and can be used as a good choice for efficient oil-water separation. The biomass aerogel has the advantages of being renewable, low in cost, environment-friendly, easy to modify by multiple active sites and the like, and is widely applied to the field of oil-water separation. However, to apply such biomass aerogels on a large scale, there is still a need to overcome the problem of low mechanical strength. Many scholars have successfully prepared the biomass aerogel capable of oil-water separation, but the problem of poor mechanical properties of the biomass aerogel is not considered, and effective methods for improving the mechanical strength of the biomass aerogel include adding a reinforcing phase, chemically crosslinking, changing a freeze casting method and the like. Although these methods improve the mechanical properties of biomass aerogels, how to effectively combine these methods to make biomass aerogels with super elasticity is still a problem to be solved.
Disclosure of Invention
In order to solve the existing problems, the invention aims to provide a preparation method of sodium alginate/typha orientalis/graphene oxide composite aerogel. According to the invention, sodium alginate is used as a skeleton, graphene oxide and typha orientalis fiber are used as reinforcing fillers and introduced into a sodium alginate three-dimensional network structure, the arrangement mode of aerogel network lamellae is changed by a bidirectional freeze casting method, and then the sodium alginate/typha orientalis/graphene oxide composite aerogel is constructed by simple freeze drying and ionic crosslinking, so that various organic pollutants in water can be synchronously removed.
The invention firstly provides sodium alginate/typha orientalis/graphene oxide composite aerogel, which is prepared by compounding three materials of sodium alginate, typha orientalis and graphene oxide; the internal structure of the obtained composite aerogel is a parallel layered structure with a honeycomb porous structure sandwiched in the middle.
The invention also provides a preparation method of the sodium alginate/typha orientalis/graphene oxide composite aerogel, which comprises the following steps:
(1) preparing a sodium alginate/typha orientalis/graphene oxide mixed solution:
A. preparing graphene oxide dispersion liquid;
B. preparing typha fiber: firstly, adding sodium chlorite into deionized water, stirring to obtain a sodium chlorite solution, and adjusting the pH value; adding typha orientalis ears, stirring, washing with deionized water until the pH value is 6, then repeatedly washing with absolute ethyl alcohol for three times, and drying to obtain dried typha fiber;
C. preparing a sodium alginate/typha orientalis/graphene oxide mixed solution: adding sodium alginate powder and typha orientalis fiber into the graphene oxide dispersion liquid, stirring, and performing ultrasonic treatment to obtain a sodium alginate/typha orientalis/graphene oxide uniform mixed solution;
(2) preparing the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel: pouring the sodium alginate/typha orientalis/graphene oxide mixed solution obtained in the step (1) into a silica gel mold with a wedge at the bottom, and coating a heat-preservation adhesive tape outside the mold to prevent the temperature from conducting with each other; the bottom of the silica gel mold is in contact with the top of the copper rod continuously cooled by liquid nitrogen for bidirectional freezing casting, and when the solution is frozen into ice blocks, the ice blocks are frozen and dried to obtain the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel;
(3) preparing the calcium ion crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel: and (3) immersing the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel obtained in the step (2) into an ethanol/water mixed solution of calcium chloride, repeatedly cleaning the aerogel by using absolute ethanol after reaction, and then performing secondary freeze drying to obtain the calcium ion crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel.
Preferably, the ratio of the sodium chlorite to the deionized water in the step (1) B is 4 g: 400 mL; the pH adjustment is to adjust the pH to 4.5 with acetic acid.
Preferably, the mass ratio of the cattail spica to the sodium chlorite in the step (1) B is 1: 1.
Preferably, the stirring in step (1) B is carried out at 1000rpm and 80 ℃ for 2 hours; the temperature of the drying was 60 ℃.
Preferably, the mass ratio of the sodium alginate powder to the typha orientalis fiber in the step (1) C is 1: 9-9: 1; the amount of the graphene oxide accounts for 1-10 wt% of the total amount of the sodium alginate powder and the cattail fiber.
Preferably, the angle of the bottom wedge in the step (2) is 10-15 degrees.
Preferably, the freeze-drying conditions in step (2) and step (3) are-40 ℃, absolute pressure 20pa and time 48 h.
Preferably, the concentration of the ethanol/water mixed solution of the calcium chloride in the step (3) is 2-4 wt%, and the reaction time is 8-12 h.
The sodium alginate/typha orientalis/graphene oxide composite aerogel prepared by the invention is applied to oil-water separation and adsorption removal of water-soluble dyes.
The invention discloses a performance test method of sodium alginate/typha orientalis/graphene oxide composite aerogel, which comprises the following steps:
(1) mechanical Property test
The mechanical properties of the aerogels were tested with a digital tensile compression tester. The stress change of the super-oleophobic sodium alginate/typha/graphene oxide composite aerogel under super elasticity water is tested under the strain of 40%, 60% and 80%, and the stress change is tested under the strain condition of 80% by multiple-cycle compression.
(2) Testing the wettability of water and oil in the air on the surface of the sodium alginate/typha/graphene oxide composite aerogel:
the wettability of water and oil in the air on the surface of the sodium alginate/typha/graphene oxide composite aerogel; in the acid-base salt, the wettability of oil on the surface of the sodium alginate/typha/graphene oxide composite aerogel; evaluation was performed by contact angle testing using a droplet shape analysis system.
(3) Simultaneous removal of insoluble oil and water soluble dye test
The sodium alginate/typha orientalis/graphene oxide composite aerogel is clamped between filtering devices, and the separation efficiency of different oils and dyes after mixing and filtering is tested. Wherein the test oil comprises toluene, rapeseed oil, hexane, pump oil, silicone oil and hexadecane; the dye includes methylene blue, gentian violet and rhodamine B.
(4) Cyclic adsorption and desorption test
The sodium alginate/typha orientalis/graphene oxide composite aerogel is clamped between filtering devices, and is desorbed by 0.5M hydrochloric acid after methylene blue solution (10ppm) is absorbed. The test is cycled for 100 times, and the change of the methylene blue absorption amount is obtained.
Has the advantages that:
(1) the sodium alginate/typha orientalis/graphene oxide composite aerogel capable of synchronously removing insoluble oil and water-soluble dye is obtained, the preparation process is simple, the cost of raw materials is low, and the obtained composite aerogel is environment-friendly and pollution-free.
(2) The sodium alginate/typha orientalis/graphene oxide composite aerogel prepared by the method has excellent mechanical properties, excellent affinity and high specific surface area; meanwhile, the graphene oxide and the typha orientalis fiber are added into the sodium alginate matrix as reinforcing fillers, so that the load borne by the sodium alginate matrix can be effectively transferred, and a three-dimensional network structure with better mechanical property can be constructed.
(3) The sodium alginate/typha orientalis/graphene oxide composite aerogel obtained by the invention has a three-dimensional parallel sheet-shaped structure, cellular porous interconnection exists between sheets, excellent mechanical properties are shown, elastic loss basically does not occur after multiple compression cycle experiments, the original shape of the composite aerogel can be effectively recovered, the composite aerogel can still be recovered to 86% of the original shape after 100 times of compression under the 80% strain condition, and the compression strength is maintained at 81% of the original strength.
(4) The sodium alginate/typha orientalis/graphene oxide composite aerogel obtained by the invention shows super oleophobicity under water, and the contact angle with oil is up to 171.74 degrees; under the condition of acid, alkali and salt, the contact angle is still as high as 150 degrees.
(5) The sodium alginate/typha orientalis/graphene oxide composite aerogel obtained by the invention can synchronously remove insoluble oil and soluble dye; the oil removal efficiency is as high as 99.59%, and the dye removal efficiency is as high as 99.05%.
(6) The sodium alginate/typha orientalis/graphene oxide composite aerogel obtained by the invention can be used for circularly adsorbing and desorbing water-soluble pollutants, and the adsorption quantity can still be maintained at 86.88% of the original adsorption quantity through 100 times of circular adsorption and desorption experiments. And without any significant change in shape.
Drawings
Fig. 1 is a diagram of a sodium alginate/typha orientalis/graphene oxide composite aerogel prepared in example 4.
Fig. 2 is a micro-topography of the sodium alginate/typha orientalis/graphene oxide composite aerogel prepared in example 4, wherein a is a low-magnification structural diagram, and b is a high-magnification structural diagram.
Fig. 3 is a stress-strain diagram a of the sodium alginate/typha/graphene oxide composite aerogel prepared in example 4 after cyclic compression under different strain conditions (40%, 60%, 80%), a stress-strain diagram b after multiple times of compression under 80% strain conditions, and a plastic deformation rate c and a strength recovery rate d after 100 times of cyclic compression under 80% strain conditions.
Fig. 4 is a photograph a of surface oil drops of the sodium alginate/typha/graphene oxide composite aerogel prepared in example 4 in water, schematic diagrams b to d of wetting behaviors, contact angles e of different oil drops under water, and contact angles f of n-hexane and the sodium alginate/typha/graphene oxide composite aerogel in NaCl (10 wt%), HCl (1mol/L) and NaOH (1 mol/L).
Fig. 5 shows that the sodium alginate/typha orientalis/graphene oxide composite aerogel prepared in example 4 is sandwiched between filtering devices to synchronously remove insoluble oil and water-soluble dye.
FIG. 6 shows the removal efficiency and flux of the aerogel prepared in example 4 under the mixed conditions of oil and dye for different oils a and different dyes b; and (c) changing the adsorption quantity of the dye through 100 times of cyclic desorption and adsorption.
Fig. 7 shows the shape change of the sodium alginate/typha orientalis/graphene oxide composite aerogel prepared in example 4 after desorption and adsorption for 100 cycles.
Detailed Description
In order to fully disclose the preparation method of the sodium alginate/typha orientalis/graphene oxide composite aerogel, the invention is further described in detail with reference to the following examples.
Example 1:
(1) preparing a sodium alginate/typha orientalis/graphene oxide uniformly-mixed solution:
A. preparing a graphene oxide dispersion liquid: adding graphene oxide powder into deionized water, and carrying out ultrasonic treatment for 2 hours to uniformly disperse the graphene oxide powder in the deionized water to obtain a uniform graphene oxide dispersion liquid;
B. preparing typha fiber: first, 50 grams of typha paniculata ears were washed with 1L of water and 1L of ethanol in sequence, 4g of sodium chlorite and 400mL of deionized water were added to a flask equipped with a mechanical stirrer and a thermometer, stirred to dissolve them sufficiently, and the pH of the sodium chlorite solution was adjusted to 4.5 with 1.2mL of acetic acid. 4g of typha paniculata was then added, stirred at 1000rpm and 80 ℃ for 2 hours, washed with deionized water to pH 6, then washed three times with absolute ethanol, the residual water removed, and dried in an oven at 60 ℃. Finally obtaining the dried cattail fiber.
C. Preparing a sodium alginate/typha orientalis/graphene oxide uniformly-mixed solution: adding sodium alginate powder and typha orientalis fiber into the graphene oxide dispersion liquid, stirring for 3 hours by magnetic force to enable the sodium alginate powder and typha orientalis fiber to be fully and uniformly mixed, and removing bubbles through ultrasonic treatment to obtain a sodium alginate/typha orientalis/graphene oxide uniform mixed solution. Wherein the mass ratio of the sodium alginate powder to the typha orientalis fiber is 1:9, and the mass of the graphene oxide is 1 wt% of the total mass of the sodium alginate powder and the typha orientalis fiber.
(2) Preparing the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel: pouring the uniformly mixed solution obtained in the step (1) into a silica gel mold with a wedge at the bottom, coating a layer of heat preservation adhesive tape outside the mold to play a role in heat preservation and heat insulation and preventing temperature mutual conduction, wherein the angle of the wedge at the bottom is 10 degrees, the bottom of the silica gel mold is contacted with the top of a copper rod which is continuously cooled by liquid nitrogen to carry out bidirectional freeze casting, when the solution is frozen into ice blocks, putting a freeze drying system to carry out freeze drying, and obtaining the non-crosslinked sodium alginate/cattail/graphene oxide composite aerogel.
(3) Preparing the calcium ion crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel: and (3) immersing the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel obtained in the step (2) into an ethanol/water (v: 8:2) mixed solution of calcium chloride with the concentration of 2 wt%, reacting for 8 hours, repeatedly cleaning aerogel by using a large amount of anhydrous ethanol, and then carrying out secondary freeze drying to obtain the calcium ion crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel. The composite aerogel was cut into dimensions of 20X 15X 40mm with a cutter for subsequent performance testing of the composite aerogel. The composite aerogel is cut into a size with the diameter of 25mm and the thickness of 10mm by a cutter, and is used for carrying out subsequent separation performance test on the composite aerogel.
Example 2:
(1) preparing a sodium alginate/typha orientalis/graphene oxide uniformly-mixed solution:
A. preparing a graphene oxide dispersion liquid: adding graphene oxide powder into deionized water, and carrying out ultrasonic treatment for 2 hours to uniformly disperse the graphene oxide powder in the deionized water to obtain a uniform graphene oxide dispersion liquid;
B. preparing typha fiber: first, 50 grams of typha paniculata ears were washed with 1L of water and 1L of ethanol in sequence, 4g of sodium chlorite and 400mL of deionized water were added to a flask equipped with a mechanical stirrer and a thermometer, stirred to dissolve them sufficiently, and the pH of the sodium chlorite solution was adjusted to 4.5 with 1.2mL of acetic acid. 4g of typha paniculata was then added, stirred at 1000rpm and 80 ℃ for 2 hours, washed with deionized water to pH 6, then washed three times with absolute ethanol, the residual water removed, and dried in an oven at 60 ℃. Finally obtaining the dried cattail fiber.
C. Preparing a sodium alginate/typha orientalis/graphene oxide uniformly-mixed solution: adding sodium alginate powder and typha orientalis fiber into the graphene oxide dispersion liquid, stirring for 3 hours by magnetic force to enable the sodium alginate powder and typha orientalis fiber to be fully and uniformly mixed, and removing bubbles through ultrasonic treatment to obtain a sodium alginate/typha orientalis/graphene oxide uniform mixed solution. Wherein the mass ratio of the sodium alginate powder to the typha orientalis fiber is 3:7, and the mass of the graphene oxide is 5 wt% of the total mass of the sodium alginate powder and the typha orientalis fiber.
(2) Preparing the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel: pouring the uniformly mixed solution obtained in the step (1) into a silica gel mold with a wedge at the bottom, coating a layer of heat preservation adhesive tape outside the mold to play a role in heat preservation and heat insulation and preventing temperature mutual conduction, wherein the angle of the wedge at the bottom is 15 degrees, the bottom of the silica gel mold is contacted with the top of a copper rod which is continuously cooled by liquid nitrogen to carry out bidirectional freeze casting, when the solution is frozen into ice blocks, putting a freeze drying system to carry out freeze drying, and obtaining the non-crosslinked sodium alginate/cattail/graphene oxide composite aerogel.
(3) Preparing the calcium ion crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel: and (3) immersing the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel obtained in the step (2) into an ethanol/water (v: 8:2) mixed solution of calcium chloride with the concentration of 4 wt%, reacting for 10 hours, repeatedly cleaning aerogel by using a large amount of anhydrous ethanol, and then carrying out secondary freeze drying to obtain the calcium ion crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel. The composite aerogel was cut into dimensions of 20X 15X 40mm with a cutter for subsequent performance testing of the composite aerogel. The composite aerogel is cut into a size with the diameter of 25mm and the thickness of 10mm by a cutter, and is used for carrying out subsequent separation performance test on the composite aerogel.
Example 3:
(1) preparing a sodium alginate/typha orientalis/graphene oxide uniformly-mixed solution:
A. preparing a graphene oxide dispersion liquid: adding graphene oxide powder into deionized water, and carrying out ultrasonic treatment for 3h to uniformly disperse the graphene oxide powder in the deionized water to obtain a uniform graphene oxide dispersion liquid;
B. preparing typha fiber: first, 50 grams of typha paniculata ears were washed with 1L of water and 1L of ethanol in sequence, 4g of sodium chlorite and 400mL of deionized water were added to a flask equipped with a mechanical stirrer and a thermometer, stirred to dissolve them sufficiently, and the pH of the sodium chlorite solution was adjusted to 4.5 with 1.2mL of acetic acid. 4g of typha paniculata was then added, stirred at 1000rpm and 80 ℃ for 2 hours, washed with deionized water to pH 6, then washed three times with absolute ethanol, the residual water removed, and dried in an oven at 60 ℃. Finally obtaining the dried cattail fiber.
C. Preparing a sodium alginate/typha orientalis/graphene oxide uniformly-mixed solution: adding sodium alginate powder and typha orientalis fiber into the graphene oxide dispersion liquid, stirring for 3 hours by magnetic force to enable the sodium alginate powder and typha orientalis fiber to be fully and uniformly mixed, and removing bubbles through ultrasonic treatment to obtain a sodium alginate/typha orientalis/graphene oxide uniform mixed solution. Wherein the mass ratio of the sodium alginate powder to the typha orientalis fiber is 7:3, and the mass of the graphene oxide is 10 wt% of the total mass of the sodium alginate powder and the typha orientalis fiber.
(2) Preparing the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel: pouring the uniformly mixed solution obtained in the step (1) into a silica gel mold with a wedge at the bottom, coating a layer of heat preservation adhesive tape outside the mold to play a role in heat preservation and heat insulation and preventing temperature mutual conduction, wherein the angle of the wedge at the bottom is 10 degrees, the bottom of the silica gel mold is contacted with the top of a copper rod which is continuously cooled by liquid nitrogen to carry out bidirectional freeze casting, when the solution is frozen into ice blocks, putting a freeze drying system to carry out freeze drying, and obtaining the non-crosslinked sodium alginate/cattail/graphene oxide composite aerogel.
(3) Preparing the calcium ion crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel: and (3) immersing the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel obtained in the step (2) into an ethanol/water (v: 8:2) mixed solution of calcium chloride with the concentration of 2 wt%, reacting for 12h, repeatedly cleaning aerogel by using a large amount of anhydrous ethanol, and then carrying out secondary freeze drying to obtain the calcium ion crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel. The composite aerogel was cut into dimensions of 20X 15X 40mm with a cutter for subsequent performance testing of the composite aerogel. The composite aerogel is cut into the size of 25mm in diameter and 10mm in thickness by a cutter and is used for carrying out subsequent separation performance test on the composite aerogel.
Example 4:
(1) preparing a sodium alginate/typha orientalis/graphene oxide uniformly-mixed solution:
A. preparing a graphene oxide dispersion liquid: adding graphene oxide powder into deionized water, and carrying out ultrasonic treatment for 2 hours to uniformly disperse the graphene oxide powder in the deionized water to obtain a uniform graphene oxide dispersion liquid;
B. preparing typha fiber: first, 50 grams of typha paniculata ears were washed with 1L of water and 1L of ethanol in sequence, 4g of sodium chlorite and 400mL of deionized water were added to a flask equipped with a mechanical stirrer and a thermometer, stirred to dissolve them sufficiently, and the pH of the sodium chlorite solution was adjusted to 4.5 with 1.2mL of acetic acid. 4g of typha paniculata was then added, stirred at 1000rpm and 80 ℃ for 2 hours, washed with deionized water to pH 6, then washed three times with absolute ethanol, the residual water removed, and dried in an oven at 60 ℃. Finally obtaining the dried cattail fiber.
C. Preparing a sodium alginate/typha orientalis/graphene oxide uniformly-mixed solution: adding sodium alginate powder and typha orientalis fiber into the graphene oxide dispersion liquid, stirring for 3 hours by magnetic force to enable the sodium alginate powder and typha orientalis fiber to be fully and uniformly mixed, and removing bubbles through ultrasonic treatment to obtain a sodium alginate/typha orientalis/graphene oxide uniform mixed solution. Wherein the mass ratio of the sodium alginate powder to the typha orientalis fiber is 9:1, and the mass of the graphene oxide is 5 wt% of the total mass of the sodium alginate powder and the typha orientalis fiber.
(2) Preparing the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel: pouring the uniformly mixed solution obtained in the step (1) into a silica gel mold with a wedge at the bottom, coating a layer of heat preservation adhesive tape outside the mold to play a role in heat preservation and heat insulation and preventing temperature mutual conduction, wherein the angle of the wedge at the bottom is 15 degrees, the bottom of the silica gel mold is contacted with the top of a copper rod which is continuously cooled by liquid nitrogen to carry out bidirectional freeze casting, when the solution is frozen into ice blocks, putting a freeze drying system to carry out freeze drying, and obtaining the non-crosslinked sodium alginate/cattail/graphene oxide composite aerogel.
(3) Preparing the calcium ion crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel: and (3) immersing the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel obtained in the step (2) into an ethanol/water (v: 8:2) mixed solution of calcium chloride with the concentration of 2 wt%, reacting for 10 hours, repeatedly cleaning aerogel by using a large amount of anhydrous ethanol, and then carrying out secondary freeze drying to obtain the calcium ion crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel. The composite aerogel was cut into dimensions of 20X 15X 40mm with a cutter for subsequent performance testing of the composite aerogel. The composite aerogel is cut into 25mm diameter and 10mm thickness by a cutter, and is used for carrying out subsequent separation performance test on the composite aerogel.
As shown in fig. 1, the surface of the sodium alginate/typha orientalis/graphene oxide composite aerogel prepared by the invention is still in a parallel layered structure and a honeycomb porous structure sandwiched between the surfaces when observed macroscopically.
As shown in fig. 2, the sodium alginate/typha orientalis/graphene oxide composite aerogel prepared by the invention has a three-dimensional parallel layered structure inside, and cellular porous interconnections exist between layers (fig. 2 a); further enlarging the image as shown in fig. 2b, typha fiber is embedded in the lamellar structure and faces different directions, sodium alginate and graphene oxide grow along typha fiber, and then a honeycomb porous structure is obtained in the parallel lamellar structure.
As shown in fig. 3, the sodium alginate/typha orientalis/graphene oxide composite aerogel prepared by the invention shows excellent mechanical properties after being compressed under different strain conditions (fig. 3 a). Through the first compression, the maximum pressure can reach 130kPa, and the problem of poor mechanical property of the biomass aerogel is solved; (fig. 3b-d) after multiple compression cycle experiments, the elastic loss is not generated basically, and the composite aerogel can be effectively recovered to the original shape. Under 80% strain, after 100 compressions, it can still return to 86% of its original shape, with the compressive strength maintained at 81% of the original strength.
As shown in fig. 4, the sodium alginate/typha orientalis/graphene oxide composite aerogel prepared by the invention floats on the water surface, and in water, oil drops are spherical on the surface of the aerogel (fig. 4a and 4d), so that the super-oleophobic property under water is shown; whereas in air, the surface of the aerogel is hydrophilic-lipophilic (fig. 4b, 4 c); (fig. 4e) the contact angle of different oil droplets on the composite aerogel surface was tested in water and found to be as high as 171.74 ° with kerosene; (FIG. 4f) the contact angle is still as high as 150 ℃ under the conditions of acid, base and salt.
As shown in fig. 5, the sodium alginate/typha orientalis/graphene oxide composite aerogel prepared by the invention is sandwiched between filtering devices to synchronously remove insoluble oil and water-soluble dye; the oil removal efficiency was as high as 99.59% (fig. 6a) and the dye removal efficiency was as high as 99.05% (fig. 6 b).
The sodium alginate/typha orientalis/graphene oxide composite aerogel prepared by the invention can be used for circularly adsorbing and desorbing water-soluble pollutants, and the adsorption quantity can still be maintained at 86.88% of the original adsorption quantity through 100 times of circular adsorption and desorption experiments (figure 6 c). And the original shape was well maintained without any significant change in shape (fig. 7).
Claims (8)
1. The sodium alginate/typha orientalis/graphene oxide composite aerogel is characterized in that the composite aerogel is prepared by compounding three materials, namely sodium alginate, typha orientalis and graphene oxide; the composite aerogel has a three-dimensional parallel flaky structure, and honeycombed porous mutual connection exists between sheets; namely, the internal structure of the composite aerogel is a parallel layered structure with a honeycomb porous structure sandwiched in the middle; the preparation method comprises the following specific steps:
(1) preparing a sodium alginate/typha orientalis/graphene oxide mixed solution:
A. preparing graphene oxide dispersion liquid;
B. preparing typha fiber: firstly, adding sodium chlorite into deionized water, stirring to obtain a sodium chlorite solution, and adjusting the pH value; adding typha orientalis ears, stirring, washing with deionized water until the pH value is 6, then repeatedly washing with absolute ethyl alcohol for three times, and drying to obtain dried typha fiber;
C. preparing a sodium alginate/typha orientalis/graphene oxide mixed solution: adding sodium alginate powder and typha orientalis fiber into the graphene oxide dispersion liquid, stirring, and performing ultrasonic treatment to obtain a sodium alginate/typha orientalis/graphene oxide uniform mixed solution; the mass ratio of the sodium alginate powder to the typha orientalis fiber is 1: 9-9: 1; the amount of the graphene oxide accounts for 1-10 wt% of the total amount of the sodium alginate powder and the cattail fiber;
(2) preparing the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel: pouring the sodium alginate/typha orientalis/graphene oxide mixed solution obtained in the step (1) into a silica gel mold with a wedge at the bottom, and coating a heat-preservation adhesive tape outside the mold to prevent the temperature from conducting with each other; the bottom of the silica gel mold is in contact with the top of the copper rod continuously cooled by liquid nitrogen for bidirectional freezing casting, and when the solution is frozen into ice blocks, the ice blocks are frozen and dried to obtain the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel;
(3) preparing the calcium ion crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel: and (3) immersing the non-crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel obtained in the step (2) into an ethanol/water mixed solution of calcium chloride, repeatedly cleaning the aerogel by using absolute ethanol after reaction, and then performing secondary freeze drying to obtain the calcium ion crosslinked sodium alginate/typha orientalis/graphene oxide composite aerogel.
2. The sodium alginate/typha orientalis/graphene oxide composite aerogel according to claim 1, wherein the amount ratio of the sodium chlorite to the deionized water in the step (1) B is 4 g: 400 mL; the pH is adjusted to 4.5 by using acetic acid; the mass ratio of the cattail spica to the sodium chlorite is 1: 1.
3. The sodium alginate/typha/graphene oxide composite aerogel according to claim 1, wherein the stirring in step (1) B is stirring at 1000rpm and 80 ℃ for 2 hours; the temperature of the drying was 60 ℃.
4. The sodium alginate/typha orientalis/graphene oxide composite aerogel according to claim 1, wherein the angle of the bottom wedge in the step (2) is 10-15 °.
5. The sodium alginate/typha orientalis/graphene oxide composite aerogel according to claim 1, wherein the freeze-drying conditions in the steps (2) and (3) are-40 ℃, 20P a absolute pressure and 48h time.
6. The sodium alginate/typha orientalis/graphene oxide composite aerogel according to claim 1, wherein the concentration of the ethanol/water mixed solution of calcium chloride in the step (3) is 2 wt% -4 wt%, and the reaction time is 8-12 h.
7. The application of the sodium alginate/typha orientalis/graphene oxide composite aerogel in the claim 1 in oil-water separation and synchronous adsorption removal of water-soluble dyes.
8. Use according to claim 7, wherein the water-soluble dye is gentian violet, methylene blue or rhodamine B.
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| CN110697692B (en) * | 2019-09-27 | 2020-08-18 | 北京石墨烯技术研究院有限公司 | Graphene aerogel three-dimensional structure and preparation method thereof |
| CN112191234A (en) * | 2020-10-09 | 2021-01-08 | 厦门理工学院 | Sodium alginate adsorption stent and preparation method and application thereof |
| CN112635731B (en) * | 2020-12-17 | 2021-11-02 | 浙江锂宸新材料科技有限公司 | Preparation method of composite nano-silicon negative electrode material based on conductive carbon aerogel and product thereof |
| CN113648978B (en) * | 2021-08-16 | 2023-06-30 | 青岛大学 | Preparation method and application of aerogel with oriented neural network structure |
| CN113952900B (en) * | 2021-10-22 | 2022-08-02 | 山东大学 | Biological polyelectrolyte aerogel, and preparation method and application thereof |
| CN116786087B (en) * | 2023-08-23 | 2023-10-20 | 鲁东大学 | Preparation method and application of PAMAM (polyamide-amine) and sulfhydryl-containing composite aerogel |
| CN117086264B (en) * | 2023-10-19 | 2023-12-19 | 中北大学 | Casting method combining frozen sand mold and gypsum mold |
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