Preparation method of polypyrrole aerogel, polypyrrole aerogel and evaporator

Abstract

The embodiment of the invention provides a preparation method of polypyrrole aerogel, the polypyrrole aerogel and an evaporator. The method comprises the steps that xanthan gum and gellan gum are mixed according to the mass ratio of 2: 1-8: 1 and then added into deionized water, stirring is conducted, and a colloidal solution is formed; sequentially adding polyethylene glycol and calcium chloride into the colloidal solution, and stirring; cooling the colloidal solution, adding a sodium bicarbonate solid, and stirring; reducing the rotating speed, stirring, dropwise adding a hydrogen peroxide solution, pouring the solution into a mold after bubbles are generated, and cooling to obtain precursor hydrogel; freezing the precursor hydrogel in liquid nitrogen to obtain a frozen product; immersing the frozen product into a pyrrole solution to obtain hydrogel permeated with the pyrrole solution; immersing the hydrogel permeated with the pyrrole solution into a ferric chloride solution, and polymerizing to obtain a polypyrrole hydrogel product; and cleaning the polypyrrole hydrogel product, freezing the polypyrrole hydrogel product in a liquid nitrogen atmosphere, and performing freeze-drying treatment to obtain the polypyrrole aerogel.

Description

Technical Field

[0001] The embodiments of the present disclosure belong to the technical field of seawater desalination, and specifically relate to a method for preparing a polypyrrole aerogel, a polypyrrole aerogel, an evaporator, and a seawater desalination method. Background Art

[0002] Seawater is an abundant water resource, and desalinating and utilizing it is an important means of obtaining fresh water. Traditional desalination uses traditional and expensive fossil fuels, which can lead to increased air pollution and greenhouse gas emissions. It also has low energy conversion efficiency and requires a large area of ​​land. Therefore, the development of new desalination technologies is urgent.

[0003] Chen et al. first proposed the concept of heat localization of solar interfacial water vapor collection system (Solar steam generation by heat localization) in Nat. Commun. This work has opened up a new path for seawater desalination. This photothermal interfacial water evaporation has the advantages of not consuming fossil energy, low carbon emissions, and low pollution, and has potential application value. Under sunlight, part of the light is absorbed by the evaporator, and the other part of the light is lost due to reflection and transmission. The light absorbed by the photothermal evaporator is converted into heat, most of which is used to heat the water absorbed inside. The water phase changes into water vapor at the interface and then dissipates into the air. The rest of the heat is transferred to the air through thermal radiation and thermal convection or to the underlying water through heat conduction.

[0004] At present, ordinary aerogels not only have a low evaporation rate and high cost, but also have low long-term durability. Therefore, it is very necessary to develop a new and efficient aerogel desalination technology. Summary of the Invention

[0005] The embodiments of the present disclosure aim to solve at least one of the technical problems existing in the prior art, and provide a method for preparing a polypyrrole aerogel, a polypyrrole aerogel, an evaporator, and a seawater desalination method.

[0006] According to a first aspect of an embodiment of the present disclosure, a method for preparing a polypyrrole aerogel is provided, comprising: mixing xanthan gum and gellan gum in a mass ratio of 2:1 to 8:1, adding the mixture to deionized water, and stirring to form a colloidal solution;

[0007] Add polyethylene glycol and calcium chloride to the colloidal solution in sequence and stir;

[0008] The colloidal solution is cooled, and solid sodium bicarbonate is added and stirred;

[0009] The speed is reduced while stirring and hydrogen peroxide solution is added dropwise. After bubbles are generated, the solution is poured into a mold and cooled to obtain a precursor hydrogel.

[0010] The precursor hydrogel is placed in liquid nitrogen and frozen to obtain a frozen product;

[0011] immersing the frozen product in a pyrrole solution to obtain a hydrogel permeated with the pyrrole solution;

[0012] The hydrogel infiltrated with pyrrole solution is immersed in ferric chloride solution to polymerize and obtain a polypyrrole hydrogel product;

[0013] The polypyrrole hydrogel product is washed, frozen in a liquid nitrogen atmosphere, and freeze-dried to obtain a polypyrrole aerogel.

[0014] Optionally, the stirring to form a colloidal solution comprises:

[0015] The colloidal solution was prepared by stirring xanthan gum and gellan gum in deionized water at 85° C. for 3 hours.

[0016] Optionally, the step of sequentially adding polyethylene glycol and calcium chloride to the colloidal solution and stirring the mixture comprises:

[0017] Polyethylene glycol was added to the colloidal solution and the mixture was stirred at 85° C. for 30 minutes; and calcium chloride was added to the colloidal solution containing polyethylene glycol and the mixture was stirred at 85° C. for 10 minutes.

[0018] Optionally, the step of cooling the colloidal solution and adding solid sodium bicarbonate followed by stirring comprises:

[0019] The colloidal solution was cooled to 55-60°C and solid sodium bicarbonate was added and stirred for 5 minutes.

[0020] Optionally, the mass ratio of the xanthan gum to the gellan gum is 6:1.

[0021] Optionally, the concentration of the hydrogen peroxide solution is 20%, the concentration of the pyrrole solution is 10%, and the concentration of the ferric chloride solution is 30%.

[0022] Optionally, the frozen product of the polypyrrole hydrogel is freeze-dried using a freeze dryer at -55°C for 24 hours.

[0023] According to a second aspect of the embodiments of the present disclosure, a polypyrrole aerogel is provided. The polypyrrole aerogel is prepared according to the above-mentioned method for preparing the polypyrrole aerogel.

[0024] According to a third aspect of the embodiments of the present disclosure, an evaporator is provided, comprising:

[0025] A collecting device, the collecting device being arranged on the periphery of the polypyrrole aerogel and provided with through holes;

[0026] A support frame, the support frame is arranged corresponding to the collecting device;

[0027] The polypyrrole aerogel mentioned above is fixed to the support frame;

[0028] an auxiliary evaporation structure, the auxiliary evaporation structure being disposed above the polypyrrole aerogel;

[0029] A temperature sensing assembly, wherein the temperature sensing assembly is fixed to the top of the polypyrrole aerogel via a rigid connecting rod;

[0030] A seawater circulation device is connected to the collection device and is configured to transport or discharge seawater to the polypyrrole aerogel.

[0031] A fourth aspect of the embodiments of the present disclosure provides a seawater desalination method, which is implemented according to the evaporator described above and includes:

[0032] The evaporator is fixed on a seawater floating support so that the polypyrrole aerogel is immersed in seawater;

[0033] The seawater is continuously delivered to the bottom of the polypyrrole aerogel at a flow rate of 5-10 L / h through a seawater circulation device;

[0034] Solar energy is used to drive the capillary rise of seawater inside the polypyrrole aerogel, and it evaporates through the synergistic effect of photothermal and photocatalysis to produce fresh water.

[0035] The beneficial effects of the embodiments of the present disclosure include:

[0036] The polypyrrole aerogel provided by the present invention includes an aerogel and polypyrrole distributed in the aerogel. Compared with the current photothermal water evaporation system, which is in a state with a higher evaporation enthalpy during the light-induced water evaporation process, the water between the staggered PPy arrays will present a meniscus under the action of capillary force. These micro-menuscules can enhance heat exchange and increase the evaporation rate. The different evaporation rates at each point on the meniscus will form a Marangoni effect, causing the water on the meniscus to gradually flow upward along the PPy array and evaporate at the same time. Finally, a portion of the water reaches the top of the PPy array and appears in the form of droplets. The droplets have a higher saturated vapor pressure and a lower evaporation enthalpy. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The figure is a schematic flow chart of a method for preparing a polypyrrole aerogel according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0039] The following is a further detailed description of the embodiments of the present application in conjunction with the accompanying drawings and examples. The detailed descriptions and drawings of the following examples are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, i.e., the present application is not limited to the described embodiments. In the description of the present application, it should be noted that, unless otherwise specified, "multiple" means more than two; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inside", "outside", etc. are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly perpendicular, but is within the allowable error range. "Parallel" is not strictly parallel, but is within the allowable error range.

[0040] It should also be noted that, in the description of this application, unless otherwise specified or limited, the terms "installed," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0041] like Figure 1 As shown, a method for preparing polypyrrole aerogel comprises:

[0042] S101. Mix xanthan gum and gellan gum in a mass ratio of 2:1 to 8:1, add to deionized water, and stir to form a colloidal solution.

[0043] S102. Add polyethylene glycol and calcium chloride to the colloidal solution in sequence and stir.

[0044] S103, cooling the colloidal solution, adding solid sodium bicarbonate and stirring.

[0045] S104, reducing the rotation speed while stirring and adding hydrogen peroxide solution dropwise, and after bubbles are generated, pouring the solution into a mold and cooling it to obtain a precursor hydrogel.

[0046] S105. Freeze the precursor hydrogel in liquid nitrogen to obtain a frozen product.

[0047] S106, immersing the frozen product in a pyrrole solution to obtain a hydrogel permeated with the pyrrole solution.

[0048] S107, immersing the hydrogel infiltrated with the pyrrole solution in a ferric chloride solution to polymerize and obtain a polypyrrole hydrogel product.

[0049] S108, washing the polypyrrole hydrogel product, freezing it in a liquid nitrogen atmosphere, and performing freeze-drying treatment to obtain a polypyrrole aerogel.

[0050] In some examples, according to an embodiment of the present invention, the photothermal material is a black polypyrrole material obtained by polymerizing a pyrrole solution using a ferric chloride solution.

[0051] In some embodiments, the stirring to form a colloidal solution comprises:

[0052] The colloidal solution was prepared by stirring xanthan gum and gellan gum in deionized water at 85° C. for 3 hours.

[0053] Specifically, xanthan gum and gellan gum were weighed at a mass ratio of 2:1, 4:1, 6:1 or 8:1 and added to deionized water, and the solution was heated to 85° C. and stirred at high speed for 3 hours.

[0054] In some embodiments, the step of sequentially adding polyethylene glycol and calcium chloride to the colloidal solution and stirring comprises:

[0055] Polyethylene glycol was added to the colloidal solution and the mixture was stirred at 85° C. for 30 minutes; and calcium chloride was added to the colloidal solution containing polyethylene glycol and the mixture was stirred at 85° C. for 10 minutes.

[0056] In some embodiments, the step of cooling the colloidal solution and adding solid sodium bicarbonate followed by stirring comprises:

[0057] The colloidal solution was cooled to 55-60°C and solid sodium bicarbonate was added and stirred for 5 minutes.

[0058] In some embodiments, the mass ratio of the xanthan gum to the gellan gum is 6:1.

[0059] In some embodiments, the concentration of the hydrogen peroxide solution is 20%, the concentration of the pyrrole solution is 10%, and the concentration of the ferric chloride solution is 30%.

[0060] In some embodiments, the frozen product of the polypyrrole hydrogel is freeze-dried using a freeze dryer at -55°C for 24 hours.

[0061] Specifically, another object of the present invention is to provide a method for preparing a polypyrrole aerogel, comprising the following steps:

[0062] S1. First, xanthan gum and gellan gum with a mass ratio of 2:1, 4:1, 6:1 or 8:1 were weighed and added to deionized water, and the solution was heated to 85°C and stirred at high speed for 3 hours to form a colloidal solution.

[0063] S2. Add polyethylene glycol to the colloidal solution and stir at 85°C for 30 minutes.

[0064] S3. Add calcium chloride to the colloidal solution and stir at 85°C for 10 minutes.

[0065] S4. Lower the solution temperature to 55-60°C, then add solid sodium bicarbonate and maintain stirring at 55-60°C for 5 minutes.

[0066] S5. After the sodium bicarbonate solid is dissolved, reduce the rotation speed and slowly add a 20% hydrogen peroxide solution. After bubbles are generated, pour the solution into a mold and cool it to obtain a precursor hydrogel.

[0067] S6. The condensed hydrogel is placed in liquid nitrogen for freezing to obtain a frozen product.

[0068] S7. Prepare a 10% pyrrole solution, and immerse the prepared precursor hydrogel in the solution so that the pyrrole solution fully fills the hydrogel.

[0069] S8. Immerse the treated hydrogel in a 30% ferric chloride solution. As time goes by, the pyrrole solution outside and inside the hydrogel begins to polymerize into polypyrrole. After immersion for 3 hours, take out the hydrogel coated with polypyrrole.

[0070] S9. Wash the polypyrrole hydrogel thoroughly until the solution is colorless, wipe off the surface moisture, and then place it on a copper block filled with liquid nitrogen for freezing;

[0071] S10, placing the frozen product in a freeze dryer for freeze drying to obtain the polypyrrole aerogel.

[0072] Specifically, the freeze dryer temperature is -55°C and the freeze drying time is 24 hours.

[0073] The present invention also provides the use of the polypyrrole aerogel as a seawater desalination material, preferably as a solar seawater desalination material. The seawater can be ordinary seawater or high-salt wastewater.

[0074] According to a second aspect of the embodiments of the present disclosure, a polypyrrole aerogel is provided. The polypyrrole aerogel is prepared according to the above-mentioned method for preparing the polypyrrole aerogel.

[0075] According to a third aspect of the embodiments of the present disclosure, an evaporator is provided, comprising:

[0076] A collecting device, the collecting device being arranged on the periphery of the polypyrrole aerogel and provided with through holes;

[0077] A support frame, the support frame is arranged corresponding to the collecting device;

[0078] The polypyrrole aerogel mentioned above is fixed to the support frame;

[0079] an auxiliary evaporation structure, the auxiliary evaporation structure being disposed above the polypyrrole aerogel;

[0080] A temperature sensing assembly, wherein the temperature sensing assembly is fixed to the top of the polypyrrole aerogel via a rigid connecting rod;

[0081] A seawater circulation device is connected to the collection device and is configured to transport or discharge seawater to the polypyrrole aerogel.

[0082] Specifically, an evaporator includes an aerogel main structure based on polypyrrole-coated aerogel colloid, wherein the aerogel main structure includes a polypyrrole coating and an aerogel matrix, a temperature sensor and a connecting rod are arranged on the aerogel evaporator layer, and a collection device is arranged on the outside of the aerogel evaporator layer.

[0083] The collecting device is cylindrical in shape and is covered with holes at its bottom to facilitate the entry of seawater and the exit of desalinated water.

[0084] The connecting rod is in a rod shape, one end of which is connected to the polypyrrole aerogel layer and is installed above the polypyrrole aerogel layer. The other end of the connecting rod is connected to a temperature sensor for monitoring temperature changes.

[0085] The polypyrrole aerogel is prepared by polymerizing a pyrrole solution and compounding it with other materials.

[0086] The seawater desalination evaporator based on polypyrrole-coated aerogel colloid further includes an auxiliary evaporation structure, which is located above the aerogel main structure and is used to enhance the evaporation effect.

[0087] The auxiliary evaporation structure is cylindrical and coincides with the central axis of the aerogel main structure. The diameter of the auxiliary evaporation structure is larger than that of the aerogel main structure.

[0088] The evaporator further comprises a seawater circulation device, which is located below the collecting device and is used for introducing seawater into and discharging seawater from the aerogel main structure.

[0089] The desalination material further includes a support frame, on which the aerogel main structure is mounted, and the support frame is generally rectangular. In some embodiments, the aerogel main structure is vertically mounted on the support frame, the auxiliary evaporation structure is located above the support frame, and the holes in the protective mesh sleeve are all located below the support frame.

[0090] The present application also provides a seawater desalination method based on a seawater desalination evaporator with polypyrrole-coated aerogel colloid; the seawater desalination method includes placing the aerogel main structure in the seawater desalination evaporator material based on polypyrrole-coated aerogel colloid in seawater, starting a seawater circulation device, and adjusting the position of the aerogel main structure and the position of the auxiliary evaporation structure.

[0091] Furthermore, the flow rate of the seawater circulation device located below the aerogel main structure is 5-10 L / h, and the flow rate of the seawater circulation device located in the auxiliary evaporation device is 2000-3000 L / m.

[0092] A fourth aspect of the embodiments of the present disclosure provides a seawater desalination method, which is implemented according to the evaporator described above and includes:

[0093] The evaporator is fixed on a seawater floating support so that the polypyrrole aerogel is immersed in seawater;

[0094] The seawater is continuously delivered to the bottom of the polypyrrole aerogel at a flow rate of 5-10 L / h through a seawater circulation device;

[0095] Solar energy is used to drive the capillary rise of seawater inside the polypyrrole aerogel, and it evaporates through the synergistic effect of photothermal and photocatalysis to produce fresh water.

[0096] Specifically, a polypyrrole aerogel is brought into contact with seawater, wherein the polypyrrole aerogel includes aerogel and polypyrrole distributed in the aerogel. The polypyrrole aerogel obtained in contact with seawater is evaporated, and the surface temperature of the polypyrrole aerogel obtained in contact with seawater is recorded using an infrared thermal imager to monitor temperature changes in real time. The evaporation is performed using a solar light source simulated by a xenon lamp, and light sources of different intensities are used to measure the evaporation rate of the aerogel. The seawater is a homemade salt solution (3.5% to 20%), and the light intensity range is 0.5 to 4 kW·m -2 .

[0097] The polypyrrole aerogel provided by the present invention includes an aerogel and polypyrrole distributed in the aerogel. Compared with the current photothermal water evaporation system, which is in a state with a higher evaporation enthalpy during the light-induced water evaporation process, the water between the staggered PPy arrays will present a meniscus under the action of capillary force. These micro-menuscules can enhance heat exchange and increase the evaporation rate. The different evaporation rates at each point on the meniscus will form a Marangoni effect, causing the water on the meniscus to gradually flow upward along the PPy array and evaporate at the same time. Finally, a portion of the water reaches the top of the PPy array and appears in the form of droplets. The droplets have a higher saturated vapor pressure and a lower evaporation enthalpy.

[0098] The polypyrrole aerogel prepared by the preparation method provided by the present invention has improved mechanical properties after being frozen and freeze-dried.

[0099] The seawater desalination technology provided by the present invention can be used to desalinate water under one sun, i.e., under one sun (1kW·m -2 ) The evaporation rate of polypyrrole aerogel is as high as 1.96 kg / m 2 ·h 2 .

[0100] It is understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present disclosure, and the present disclosure is not limited thereto. Those skilled in the art may make various modifications and improvements without departing from the spirit and substance of the present disclosure, and such modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A method for preparing a polypyrrole aerogel, characterized in that: include: Mix xanthan gum and gellan gum in a mass ratio of 2:1 to 8:1, add to deionized water, and stir to form a colloidal solution; Add polyethylene glycol and calcium chloride to the colloidal solution in sequence and stir; The colloidal solution is cooled, and solid sodium bicarbonate is added and stirred; The speed is reduced while stirring and hydrogen peroxide solution is added dropwise. After bubbles are generated, the solution is poured into a mold and cooled to obtain a precursor hydrogel. The precursor hydrogel is placed in liquid nitrogen and frozen to obtain a frozen product; immersing the frozen product in a pyrrole solution to obtain a hydrogel permeated with the pyrrole solution; The hydrogel infiltrated with pyrrole solution is immersed in ferric chloride solution to polymerize and obtain a polypyrrole hydrogel product; The polypyrrole hydrogel product is washed, frozen in a liquid nitrogen atmosphere, and freeze-dried to obtain a polypyrrole aerogel.

2. The preparation method according to claim 1, characterized in that The stirring to form a colloidal solution comprises: The colloidal solution was prepared by stirring xanthan gum and gellan gum in deionized water at 85° C. for 3 hours.

3. The preparation method according to claim 2, characterized in that The method of sequentially adding polyethylene glycol and calcium chloride to the colloidal solution and stirring the mixture comprises: Polyethylene glycol was added to the colloidal solution and the mixture was stirred at 85° C. for 30 minutes; and calcium chloride was added to the colloidal solution containing polyethylene glycol and the mixture was stirred at 85° C. for 10 minutes.

4. The preparation method according to claim 1, characterized in that The step of cooling the colloidal solution and adding solid sodium bicarbonate followed by stirring comprises: The colloidal solution was cooled to 55-60°C and solid sodium bicarbonate was added and stirred for 5 minutes.

5. The preparation method according to claim 1, characterized in that The mass ratio of the xanthan gum to the gellan gum is 6:

1.

6. The preparation method according to claim 1, characterized in that The concentration of the hydrogen peroxide solution is 20%, the concentration of the pyrrole solution is 10%, and the concentration of the ferric chloride solution is 30%.

7. The preparation method according to claim 1, characterized in that The frozen product of the polypyrrole hydrogel was freeze-dried at -55°C using a freeze dryer for 24 hours.

8. A polypyrrole aerogel, characterized in that The polypyrrole aerogel is prepared according to the method for preparing the polypyrrole aerogel according to any one of claims 1 to 7.

9. An evaporator, characterized in that: include: A collecting device, the collecting device being arranged on the periphery of the polypyrrole aerogel and provided with through holes; A support frame, the support frame is arranged corresponding to the collecting device; The polypyrrole aerogel according to claim 8, wherein the polypyrrole aerogel is fixed to the support frame; an auxiliary evaporation structure, the auxiliary evaporation structure being disposed above the polypyrrole aerogel; A temperature sensing assembly, wherein the temperature sensing assembly is fixed to the top of the polypyrrole aerogel via a rigid connecting rod; A seawater circulation device is connected to the collection device and is configured to transport or discharge seawater to the polypyrrole aerogel.

10. A seawater desalination method, which is implemented using the evaporator according to claim 9, characterized in that: include: The evaporator is fixed on a seawater floating support so that the polypyrrole aerogel is immersed in seawater; The seawater is continuously delivered to the bottom of the polypyrrole aerogel at a flow rate of 5-10 L / h through a seawater circulation device; Solar energy is used to drive the capillary rise of seawater inside the polypyrrole aerogel, and it evaporates through the synergistic effect of photothermal and photocatalysis to produce fresh water.

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