Method for preparing all-biobased porous photothermal composite materials in multiple process sequences

Abstract

The present invention discloses a method for preparing a fully bio-based porous photothermal composite material in a multi-step sequence, and belongs to the field of polymer materials and their processing technology. The method of the present invention comprises the following steps S1, premixing wood powder, bio-based polymer materials and bio-based melanin; S2, melt blending the premix obtained in step S1 using a mixing device, and then compression molding a multi-phase composite material; S3, placing the multi-phase composite material obtained in step S2 in a mold and sealing it, and performing a carbonization treatment to obtain a fully bio-based porous photothermal composite material. The fully bio-based porous photothermal composite material prepared by the present invention is applied to the fields of seawater desalination, sewage treatment, photothermal power generation, etc. It also has the characteristics of continuous micropores, surface micro-nanostructures and uniformly distributed carbon dots. The three work together to effectively improve the material's photothermal conversion, water molecule transmission and purification capabilities, which is conducive to promotion and application.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials and processing thereof, and in particular to a method for preparing a fully bio-based porous photothermal composite material by sequentially performing multiple steps. Background Art

[0002] People's demand for water is increasing day by day, while the fresh water resources on the earth are very limited. The lack of fresh water resources has become a global problem. The ocean area accounts for about 71% of the earth's surface area. There are huge water resources. How to turn it into fresh water that can be used by humans has become an urgent problem to be solved. Therefore, it is particularly important to develop efficient and reliable seawater desalination technology.

[0003] At present, the mainstream seawater desalination technologies include electrodialysis, multi-stage flash evaporation, reverse osmosis, etc. Electrodialysis is a method of selectively permeating anions and cations in seawater with the help of ion exchange membranes and the action of direct current electric fields, thereby separating fresh water from concentrated brine. Multi-stage flash evaporation refers to a distillation desalination method in which seawater is heated and sequentially passed through multiple flash distillation chambers with gradually decreasing temperatures and pressures for evaporation and condensation. The main driving force of the reverse osmosis method is the pressure difference. This method uses a semipermeable membrane that only allows solvents to pass through but not solutes to separate seawater from fresh water. In addition, polymer-based foams prepared from polymer materials are also widely used in solar evaporation. The preparation process is simplified, but the materials used are often non-degradable, causing white pollution and microplastics. These methods have their own strengths, but there are still one or more of the following technical defects, such as excessive energy consumption in the material production process, complex preparation process and extremely long cycle, which will lead to huge economic burdens and greenhouse gas emissions, as well as pollution to the environment after disposal, which is not conducive to sustainable development. Therefore, it is particularly important to develop a green, simple to make, low-cost and biodegradable evaporation material. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a method for preparing a fully bio-based porous photothermal composite material in a multi-step sequence. The prepared fully bio-based porous photothermal composite material has the characteristics of being green, renewable in raw materials and biodegradable, and can effectively solve the problem of water shortage and reduce the pollution to the environment during the desalination process.

[0005] The present invention also provides a fully bio-based porous photothermal composite material prepared by the above method.

[0006] The present invention also provides the application of the all-biobased porous photothermal composite material prepared by the above method.

[0007] According to a first aspect of the present invention, a method for preparing a fully bio-based porous photothermal composite material in a multi-step sequence is proposed, the method comprising the following steps:

[0008] S1, premixing wood powder, bio-based polymer material and bio-based melanin;

[0009] S2, melt-blending the premix obtained in step S1 by using a mixing device, and then compression molding to form a multiphase composite material;

[0010] S3, placing the multiphase composite material obtained in step S2 in a mold and sealing it, and performing a carbonization treatment to obtain the all-biobased porous photothermal composite material.

[0011] The method for preparing a fully bio-based porous photothermal composite material by a multi-step sequence according to the first aspect of the present invention has at least the following beneficial effects:

[0012] (1) The preparation method adopted by the present invention uses biomelanin, bio-based polymer materials and wood powder as raw materials, and simultaneously forms a fully bio-based porous photothermal composite material with continuous micropores inside, surface micro-nano structure and a large number of evenly distributed carbon dots through mixing and carbonization treatment.

[0013] (2) The present invention improves the compatibility of the interface between wood powder and bio-based polymer materials by using a mixing process to modify the bio-based polymer materials with bio-melanin.

[0014] (3) The present invention uses carbonization treatment to perform high-temperature calcination on the multiphase composite material to carbonize the wood powder inside the material, so that the oligomers in the wood powder are decomposed, part of the starch is degraded and carbonized, and the free water escapes due to heat, ultimately forming a fully bio-based porous photothermal composite material with a continuous pore structure.

[0015] (4) The present invention adopts a preparation method with multiple steps such as mixing and carbonization, and extremely low-cost all-biobased materials as preparation raw materials to prepare an all-biobased porous photothermal composite material with good evaporation performance, which greatly reduces the production cost of existing seawater desalination. No other chemical reagents are used in the preparation process, and the material can be degraded after being discarded, without polluting the environment.

[0016] According to some embodiments of the present invention, in step S1, the bio-based polymer material includes a bio-based material rich in hydrogen bonds.

[0017] According to some embodiments of the present invention, in step S1, the bio-based polymer material includes at least one of starch, cellulose and PVA materials.

[0018] Preferably, in step S1, the bio-based polymer material is starch.

[0019] Among them, bio-based polymer materials rich in hydrogen bonds and good hydrophilicity can be used as the preparation raw materials of the present invention. For example, starch is used as the matrix of the all-bio-based porous photothermal composite material, which has good hydrophilicity. Part of the starch on the surface of the all-bio-based porous photothermal composite material will be carbonized into carbon dots.

[0020] According to some embodiments of the present invention, in step S1, the wood powder is sieved with a mesh size of 48 to 300 meshes.

[0021] The wood powder is a powder made from common wood, which is coated with starch and then carbonized to form holes, and the particle size of the wood powder is related to the aperture of the continuous holes. According to some embodiments of the present invention, in step S1, the biomelanin includes a biomaterial with melanin particles.

[0022] According to some embodiments of the present invention, in step S1, the biomelanin includes at least one of cuttlefish ink and squid ink.

[0023] Preferably, in step S1, the biomelanin is cuttlefish ink.

[0024] The biomelanin has good photothermal properties and can easily absorb the heat from sunlight and convert it into the heat required for evaporating seawater.

[0025] According to some embodiments of the present invention, in step S1, the mass percentage of the bio-based polymer material in the premixture is 30% to 50%, the mass percentage of the wood powder is 30% to 60%, and the mass percentage of the biomelanin is 10% to 30%.

[0026] Preferably, in step S1, the mass percentage of starch in the mixture is about 40%, the mass percentage of wood powder is about 50%, and the mass percentage of cuttlefish ink is about 10%.

[0027] In step S1, the mass ratio of starch to wood powder is 1:1-2, for example, about 4:5.

[0028] According to some embodiments of the present invention, in step S1, the specific operation steps of premixing the wood powder, bio-based polymer material and bio-melanin include: mixing the wood powder, bio-based polymer material and bio-melanin in proportion and entering into a mixing machine for premixing.

[0029] According to some embodiments of the present invention, in step S1, the rotation speed of the mixing machine is 500-600 r / min.

[0030] Preferably, the rotating speed of the mixing machine is about 550 r / min.

[0031] Through high-speed mechanical premixing, the materials are fully dispersed and premixed to ensure that the wood powder is dispersed in the starch matrix and that the biomelanin can fully penetrate into the surface of the bio-based polymer material and the gaps between particles, and the composite material exhibits disorder inside.

[0032] According to some embodiments of the present invention, in step S2, the mixing equipment includes at least one of a rotor mixer, a single-screw extruder and a twin-screw extruder.

[0033] Preferably, in step S2, the mixing equipment is a rotor mixer.

[0034] According to some embodiments of the present invention, in step S2, the temperature of the melt blending process is 110-140°C.

[0035] Preferably, in step S2, the temperature of the melt blending process is about 125°C.

[0036] According to some embodiments of the present invention, in step S2, the melt blending treatment time is 8 to 15 minutes.

[0037] Preferably, in step S2, the melt blending process is performed for about 12 minutes.

[0038] According to some embodiments of the present invention, in step S2, the rotor speed of the mixing equipment is 30-60 rpm.

[0039] Preferably, in step S2, the rotor speed of the mixing equipment is 45 rpm.

[0040] The materials are fully mixed and dispersed by melt blending treatment through mixing equipment. The bio-melanin fully plasticizes and modifies the surface of bio-based polymer materials and wood powder, improves the interfacial compatibility of starch and wood powder and makes them adhere tightly. Subsequently, they are molded into dense multiphase composite materials through low-temperature and high-pressure molding. During the melt blending process of the rotor mixer, the blend formed by starch, wood powder and cuttlefish ink is evenly dispersed in the starch matrix under the alternating shear-extrusion action of the mixer.

[0041] According to some embodiments of the present invention, in step S3, the temperature of the carbonization treatment is 100-360°C.

[0042] According to some embodiments of the present invention, in step S3, the carbonization treatment time is 30 minutes to 3 hours.

[0043] According to some embodiments of the present invention, in step S3, the equipment for carbonization treatment is a muffle furnace.

[0044] According to some embodiments of the present invention, in step S3, the carbonization treatment includes a first stage of constant temperature and a second stage of constant temperature.

[0045] According to some embodiments of the present invention, in step S3, the temperature of the first constant temperature is 100-130°C.

[0046] According to some embodiments of the present invention, in step S3, the first constant temperature time is 30 to 50 minutes.

[0047] According to some embodiments of the present invention, in step S3, the temperature of the second stage constant temperature is 180-360°C.

[0048] According to some embodiments of the present invention, in step S3, the time of the second stage constant temperature is 1 to 3 hours.

[0049] During the carbonization treatment, a muffle furnace is used for high-temperature calcination. The temperature of the muffle furnace is first raised to 100-130°C and maintained for 30-50 minutes to evaporate the free water inside the composite material. The temperature of the muffle furnace is then raised to 180-360°C for 1-3 hours to carbonize the wood powder inside the material. When the bio-based polymer material includes starch, the oligomers in the wood powder are decomposed, the starch is partially degraded and carbonized, and the free water escapes due to heat, ultimately forming a fully bio-based porous composite material with continuous micro-nano pores and a large number of evenly distributed carbon points.

[0050] According to some embodiments of the present invention, in step S3, the mold is a non-overflow die, and the size of the mold cavity is slightly larger than the sample size.

[0051] According to some embodiments of the present invention, in step S3, after placing the mixture in a closed mold, the air content in the closed mold is 5% to 10%.

[0052] The mixture is placed in a sealed mold but does not fill up the sealed mold, leaving a certain gap, i.e., the air content.

[0053] According to some embodiments of the present invention, in step S3, the conditions of the compression molding process are: a temperature of 50 to 80° C. and a pressure of 10.0 MPa≤p<100.0 MPa.

[0054] Preferably, in step S3, the conditions of the compression molding process are: temperature of 60-75° C.; pressure of 50.0 MPa≤p<90.0 MPa.

[0055] More preferably, in step S3, the conditions of the compression molding process are: temperature of 65° C. and pressure of 85.0 MPa.

[0056] After low-temperature and high-pressure molding treatment, the material is formed into a dense multi-phase all-biobased porous photothermal composite material.

[0057] According to a second aspect of the present invention, a fully bio-based porous photothermal composite material is provided, wherein the fully bio-based porous photothermal composite material has continuous pores.

[0058] The all-biobased porous photothermal composite material according to the second aspect of the present invention has at least the following beneficial effects:

[0059] The all-biobased porous photothermal composite material described in the present invention has the characteristics of continuous micropores, surface micro-nanostructures and uniformly distributed carbon dots. The three work together to effectively improve the material's photothermal conversion, water molecule transmission and purification capabilities.

[0060] Carbon dots have good heat absorption, converting sunlight into heat. The micro-nano structure increases the specific surface area and the evaporation area. The continuous holes promote the evaporation and transportation of water under the action of heat.

[0061] The all-biobased porous photothermal composite material described in the present invention can achieve completely zero fossil energy consumption during use, effectively solving the problem of excessive energy consumption in the existing seawater desalination process.

[0062] According to some embodiments of the present invention, the continuous holes have a pore diameter of 50 to 300 μm.

[0063] The porosity of the pores is determined by the wood powder content. The higher the wood powder content, the richer the pores left after carbonization.

[0064] According to a third aspect of the present invention, a fully bio-based porous photothermal composite material is proposed for use in the fields of seawater desalination, sewage treatment and photothermal power generation.

[0065] The application of the all-biobased porous photothermal composite material according to the third aspect of the present invention has at least the following beneficial effects:

[0066] The present invention applies the all-biobased porous photothermal composite material to fields such as seawater desalination, sewage treatment, and photothermal power generation, effectively improving the material's photothermal conversion, water molecule transmission and purification capabilities. It is healthy and non-toxic, has high economic benefits, and is conducive to wide promotion and application.

[0067] If there is no special explanation, the actual meaning of “about” in the present invention is that the error is allowed to be within the range of ±2%, for example, about 100 is actually 100±2%×100.

[0068] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0070] Figure 1 Schematic diagram of the preparation process of the all-biobased porous photothermal composite material according to an embodiment of the present invention;

[0071] Figure 2 It is a schematic diagram of the seawater desalination process according to an embodiment of the present invention. DETAILED DESCRIPTION

[0072] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0073] Example 1

[0074] This embodiment provides a fully bio-based porous photothermal composite material prepared by a multi-step sequence, which is prepared from the following raw materials in terms of mass percentage:

[0075] Wood flour 50%;

[0076] Starch 40%;

[0077] Squid ink 10%.

[0078] This embodiment also provides a method for preparing a fully bio-based porous photothermal composite material in a multi-step sequence, which is prepared by the following steps:

[0079] Step 1: First, starch, wood powder and cuttlefish ink in a certain mass ratio are added into a high-speed mixer in sequence, and mixed thoroughly at a speed of 550 r / min, wherein the wood powder content is 50%, the starch content is 40% and the cuttlefish ink content is 10%.

[0080] Step 2: Add the premix into a rotor mixer for melt blending. The mixer temperature is 140°C, the mixing time is 15 min, and the rotor speed is 60 rpm. The mixture obtained by melt blending is molded into a dense multiphase composite material under conditions of 65°C and 85 MPa.

[0081] Step 3: Place the composite material in a sealed mold and seal it, then use a muffle furnace for high-temperature calcination to carbonize the wood powder and starch inside the material. The calcination mold is a non-overflowing compression mold. After placing the sample, the air content in the chamber is about 10%. The specific carbonization process is divided into two stages: in the first stage, the muffle furnace is heated to 120°C and maintained for 40 minutes to evaporate the free water inside the composite material; in the second stage, the muffle furnace is heated to 300°C and the carbonization time is 2 hours to obtain a fully bio-based porous photothermal composite material. The preparation process of the fully bio-based porous photothermal composite material is as follows Figure 1 The fully bio-based porous photothermal composite material prepared in this embodiment has continuous micropores, surface micro-nanostructures and uniformly distributed carbon dots. The pore size of the continuous pores is 50 to 300 μm. The specific structural features are as follows: Figure 1 shown.

[0082] Example 2

[0083] This embodiment provides an application of a fully bio-based porous photothermal composite material prepared by a multi-step sequence. The fully bio-based porous photothermal composite material prepared in Example 1 is applied to seawater desalination. The specific seawater desalination process is as follows: Figure 2 shown.

[0084] Since the all-biobased porous photothermal composite material provided in Example 1 uses bio-based raw materials, it can be directly degraded in the environment after retirement without the need for additional post-processing. Because the all-biobased porous photothermal composite material obtained in Example 1 contains abundant carbon dots, it can quickly and efficiently absorb sunlight and convert it into heat to promote the evaporation of water; the addition of biomelanin is also to make the material appear black and enhance the photothermal conversion capacity. The interconnected channels in the all-biobased porous photothermal composite material can also significantly increase the transport speed of water molecules and provide channels for the transpiration of water vapor. In summary, due to the preparation method of multiple process sequences and the combination of material structure and preparation raw materials, the all-biobased porous photothermal composite material provided by the present invention is green and environmentally friendly, and has broad application prospects in the fields of seawater desalination, sewage treatment and photothermal power generation.

[0085] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for preparing a fully bio-based porous photothermal composite material in a multi-step sequence, characterized in that: The method comprises the following steps: S1. Premixing wood powder, bio-based polymer material and bio-melanin; wherein the bio-based polymer material is starch; S2, melt-blending the premix obtained in step S1 using a mixing device, and then compression molding the premix into a multiphase composite material; S3, placing the multiphase composite material obtained in step S2 in a mold and sealing it, and performing a carbonization treatment to obtain the all-biobased porous photothermal composite material; Wherein, in step S2, the temperature of the melt blending treatment is 110-140°C; In step S3, the carbonization treatment includes a first stage of constant temperature and a second stage of constant temperature; wherein the temperature of the first stage of constant temperature is 100-130°C; and the temperature of the second stage of constant temperature is 180-360°C.

2. The method for preparing a fully bio-based porous photothermal composite material according to claim 1, characterized in that: In step S1, the biomelanin includes at least one of cuttlefish ink and squid ink.

3. The method for preparing a fully bio-based porous photothermal composite material according to claim 1, characterized in that: The melt blending treatment time is 8 to 15 minutes.

4. The method for preparing a fully bio-based porous photothermal composite material according to claim 1, characterized in that: The carbonization treatment time is 30 minutes to 3 hours.

5. The method for preparing a fully bio-based porous photothermal composite material according to claim 1, characterized in that: The first stage of constant temperature lasts for 30 to 50 minutes.

6. The method for preparing a fully bio-based porous photothermal composite material according to claim 1, characterized in that: The duration of the second stage is 1 to 3 hours.

7. The method for preparing a fully bio-based porous photothermal composite material according to claim 1, characterized in that: In step S1, the mass percentage of the wood powder in the premixture is 30% to 60%, the mass percentage of the bio-based polymer material is 30% to 50%, and the mass percentage of the biomelanin is 10% to 30%.

8. A fully bio-based porous photothermal composite material prepared by the method according to any one of claims 1 to 7, characterized in that: The all-biobased porous photothermal composite material has continuous pores.

9. The all-biobased porous photothermal composite material according to claim 8, characterized in that: The continuous holes have a pore diameter of 50 to 300 μm.

10. Application of the all-biobased porous photothermal composite material prepared by the method according to any one of claims 1 to 7 in the fields of seawater desalination, sewage treatment and photothermal power generation.

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