Photo-thermal conversion hollow fiber composite ceramic membrane, preparation method and application

Abstract

The invention relates to the technical field of salt water desalination, in particular to a photo-thermal conversion hollow fiber composite ceramic membrane and a preparation method and application thereof.The preparation method includes the steps that a ceramic membrane suspension is prepared from coal gangue powder, a binder, a plasticizer, a dispersing agent and an organic solvent; preparing a ceramic membrane blank by using the ceramic membrane suspension; and finally, calcining the ceramic membrane green body, and carrying out polymerization reaction on the surface of the calcined ceramic membrane green body by using a pyrrole graphene oxide mixed solution to obtain the photo-thermal conversion hollow fiber composite ceramic membrane. According to the method, coal gangue powder is used as a raw material, preparation of the low-cost and high-performance photo-thermal conversion hollow fiber composite ceramic membrane is achieved, the composite ceramic membrane is used for a strong brine permeation treatment process, energy consumption can be effectively reduced, the raw material cost is reduced, the environment-friendly concept of treating waste with waste is achieved, and the composite ceramic membrane has remarkable market potential and is worthy of popularization and application. The problem of coal gangue treatment and the problem of high energy consumption of a strong brine permeation treatment process in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of salt water desalination, and in particular to a photothermal conversion hollow fiber composite ceramic membrane, a preparation method and an application thereof. Background Art

[0002] Coal gangue is solid waste generated during coal mining and washing. It accompanies coal seams during the coal formation process, including three types: tunneling gangue, mining gangue, and washing gangue. The accumulated stock of coal gangue is huge and continues to grow. About 300 to 350 million tons of coal gangue are produced each year and are difficult to handle. They are often filled in ditches and piled up on mountains. When in contact with air or natural leaching, they will spontaneously combust or leak a large amount of acid mine wastewater. The treatment cost is high, which can easily lead to waste of resources and cause serious pollution to the ecological environment. The main components of coal gangue include silicates, aluminates, and a small amount of iron oxides. Among them, silicon and aluminum have the highest content, and have certain resource potential.

[0003] As an efficient membrane separation technology, reverse osmosis technology is widely used in the fields of seawater desalination, industrial wastewater treatment, and pure water preparation. However, this technology produces a large amount of high-salt reverse osmosis concentrated water, which is directly discharged into the environment and causes serious pollution to the soil, water bodies, etc., which does not meet the current energy conservation and emission reduction and "zero emission" requirements. Traditional reverse osmosis concentrated brine treatment processes include ultra-high pressure reverse osmosis, multi-stage flash evaporation, mechanical evaporation and other methods, but they face many problems such as high energy consumption, expensive operating costs and low evaporation efficiency during use. Compared with traditional treatment technologies, solar-driven evaporation and concentration of reverse osmosis concentrated brine technology has attracted widespread attention as a low-cost, efficient evaporation, green and sustainable treatment technology. Therefore, how to apply coal gangue to solar-driven evaporation and concentration of reverse osmosis concentrated brine technology is the key to solving the problems of coal gangue treatment and the high energy consumption of osmotic concentrated brine treatment process. Summary of the invention

[0004] In view of the problems of gangue treatment in the prior art and the high energy consumption of the concentrated brine treatment process, the present invention provides a photothermal conversion hollow fiber composite ceramic membrane.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for preparing a photothermal conversion hollow fiber composite ceramic membrane, comprising: Prepare a ceramic membrane suspension; wherein, by mass percentage, the ceramic membrane suspension includes 46% to 51.4% of coal gangue powder, 0.5% to 1% of a binder, 4% to 6% of a plasticizer, 0.5% to 1% of a dispersant and 43% to 46% of an organic solvent; Using ceramic membrane suspension to prepare ceramic membrane green body; calcining the ceramic membrane green body to obtain a coal gangue hollow fiber ceramic membrane substrate; A photothermal conversion hollow fiber composite ceramic membrane is obtained by polymerizing the surface of a ceramic membrane substrate using a pyrrole graphene oxide mixed solution; wherein the pyrrole graphene oxide mixed solution comprises pyrrole, graphene oxide, an oxidant, and an initiator, wherein the mass concentration of graphene oxide is 0.1% to 0.4%, the mass concentration of the initiator is 0.1% to 0.7%, and the molar ratio of the oxidant to the pyrrole monomer is (1:1) to (4:1).

[0006] Optionally, the binder is polyvinyl pyrrolidone, sodium carboxymethyl cellulose or hydroxypropyl methylcellulose; the organic solvent is dimethylformamide, dimethylacetamide or N-methylpyrrolidone; the plasticizer is dibutyl phthalate, dioctyl adipate or polyether sulfone; the dispersant is polyacrylic acid or polyethylene glycol; and the particle size of the coal gangue powder is 10 to 2 µm.

[0007] Optionally, the oxidant is sulfuric acid, ferric chloride or hydrogen peroxide; and the initiator is ammonium persulfate or potassium persulfate.

[0008] Optionally, the method for preparing the ceramic membrane suspension is: 46% to 51.4% of coal gangue powder, 0.5% to 1% of a binder, 0.5% to 1% of a dispersant and 43% to 46% of an organic solvent are placed in a ball mill according to a proportion, mixed at a speed of 200 to 300 rp / min, 4% to 6% of a plasticizer is added, ball milling and stirring are continued for 20 to 28 hours, and vacuum degassing is performed to obtain a ceramic membrane suspension; the grinding balls in the ball mill include grinding balls with a diameter of 15 mm and grinding balls with a diameter of 12 mm, and the mass ratio of the grinding balls with a diameter of 15 mm to the grinding balls with a diameter of 12 mm is 1:3.

[0009] Optionally, the method for preparing a ceramic membrane body using a ceramic membrane suspension is: The ceramic membrane suspension is prepared into a ceramic membrane body by dry-wet spinning phase transfer. The outer diameter of the spinneret used for dry-wet spinning phase transfer is 2.0-5.0 mm, the inner diameter is 1.0-2.5 mm, the flow rate of the ceramic membrane suspension is 10-15 mL / min, and the flow rate of pure water is 10-20 mL / min.

[0010] Optionally, the method of calcining the ceramic membrane green body to obtain the coal gangue hollow fiber ceramic membrane substrate is: The ceramic membrane blank is placed at 1000° C. to 1300° C. and sintered for 150 to 240 minutes to obtain a coal gangue hollow fiber ceramic membrane substrate.

[0011] Optionally, the method of using the pyrrole graphene oxide mixed solution to polymerize the surface of the ceramic membrane substrate to obtain the photothermal conversion hollow fiber composite ceramic membrane is: The ceramic membrane substrate is immersed in a mixed solution of pyrrole, graphene oxide and initiator for 5 to 30 minutes, and then an oxidant is added to the mixed solution of pyrrole, graphene oxide and initiator to carry out polymerization reaction for 300 to 650 minutes to obtain a photothermal conversion hollow fiber composite ceramic membrane.

[0012] A photothermal conversion hollow fiber composite ceramic membrane is prepared using the above-mentioned photothermal conversion hollow fiber composite ceramic membrane preparation method.

[0013] A solar thermal evaporation system, comprising light-transmitting glass, a solar thermal conversion component, a tubular fan, a circulating water pump, a reverse osmosis concentrated water tank, a concentration tank, an evaporation crystallization device and a condensation device; the solar thermal conversion component comprises the above-mentioned photothermal conversion hollow fiber composite ceramic membrane; the light-transmitting glass is arranged on the outside of the solar thermal conversion component; the tubular fan is arranged on the light-transmitting glass; The reverse osmosis concentrated water output from the reverse osmosis concentrated water pool enters the photothermal conversion hollow fiber composite ceramic membrane in turn through the concentration tank and the circulating water pump; the water evaporated by the photothermal conversion hollow fiber composite ceramic membrane under solar radiation enters the condensation device for condensation to form cooling water; the reverse osmosis concentrated water evaporated and concentrated by the photothermal conversion hollow fiber composite ceramic membrane enters the evaporation crystallization device.

[0014] Such as the application of the photothermal conversion hollow fiber composite ceramic membrane in water treatment.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing a photothermal conversion hollow fiber composite ceramic membrane, which comprises preparing a ceramic membrane suspension using coal gangue powder, a binder, a plasticizer, a dispersant and an organic solvent; then preparing a ceramic membrane blank using the ceramic membrane suspension; finally, calcining the ceramic membrane blank and polymerizing the surface of the calcined ceramic membrane blank using a pyrrole graphene oxide mixed solution to obtain a photothermal conversion hollow fiber composite ceramic membrane. The method uses coal gangue powder as a raw material, realizes the preparation of a low-cost, high-performance photothermal conversion hollow fiber composite ceramic membrane, and uses it for the treatment process of infiltrating concentrated brine, which can not only effectively reduce energy consumption, but also reduce the cost of raw materials, realize the environmental protection concept of "treating waste with waste", and has significant market potential.

[0016] The present invention also provides a photothermal conversion hollow fiber composite ceramic membrane, which is prepared by the preparation method of the above-mentioned photothermal conversion hollow fiber composite ceramic membrane. The prepared photothermal conversion hollow fiber composite ceramic membrane has a large number of capillary channels. This is because the two-dimensional sheet structure of graphene oxide has rich carboxyl and hydroxyl functional groups, which can react with the amine groups on the pyrrole molecules in a network cross-linking reaction. After the pyrrole monomer is added to the graphene oxide, a three-dimensional network of capillary micro-nano laminated channels is formed through polymerization reaction, and a PPy / GO photothermal conversion active layer is formed on the surface of the gangue hollow fiber ceramic membrane substrate, providing a large number of capillary channels; the presence of such capillary channels increases the water transmission path, reduces the mass transfer resistance of water in the active layer, and helps to improve the permeation flux and evaporation efficiency of water. Compared with ordinary capillaries, it has significant photothermal conversion performance, not only with a high heat transfer rate with brine, but also with a higher evaporation efficiency of brine. At the same time, the PPy / GO photothermal conversion active layer can enhance the hydrophilicity of the membrane surface, reduce the surface energy of the active layer, and quickly transfer water molecules to the membrane surface to generate water vapor. The lower surface energy can effectively avoid the nucleation of salt ion crystallization, inhibit salt aggregation, slow down the crystallization of salt in concentrated brine, and prevent the formation of salt scale to block the membrane pores. Therefore, the photothermal conversion hollow fiber composite ceramic membrane is characterized by high efficiency, durability, and low cost, and has broad application prospects in the fields of new energy and environmental protection.

[0017] The present invention also provides a solar thermal evaporation system, which is coupled with solar-driven re-concentration and reduction of reverse osmosis concentrated water by setting up light-transmitting glass, solar thermal conversion components, tubular fans, circulating water pumps, reverse osmosis concentrated water tanks, concentration tanks, evaporation crystallization devices and condensation devices, and greatly improves the evaporation efficiency of reverse osmosis concentrated water by concentrating osmotic concentrated brine under the premise of low energy consumption. Using solar energy as a driving force for photothermal conversion can effectively avoid the high energy and high cost problems in traditional treatment methods. The evaporation system has the characteristics of low maintenance cost and low energy consumption, and provides an efficient and sustainable solution for reverse osmosis concentrated water treatment.

[0018] The application of the photothermal conversion hollow fiber composite ceramic membrane in water treatment as mentioned above not only realizes the environmental protection concept of "treating waste with waste" and solves the problem of high cost of coal gangue treatment, but also has the characteristics of low energy consumption, high treatment efficiency, environmental friendliness and good flexibility. It provides a sustainable solution for water treatment, which is especially suitable for the treatment of energy-shortage or high-salt and highly polluted water bodies, and generates huge economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a schematic diagram of a process for preparing a photothermal conversion hollow fiber composite ceramic membrane.

[0020] Figure 2 This is a structural diagram of a solar thermal evaporation system of the present invention.

[0021] Among them, 1-light-transmitting glass, 2-solar energy photothermal conversion component, 3-tubular fan, 4-circulating water pump, 5-reverse osmosis concentrated water tank, 6-concentration tank, 7-evaporation crystallization device, 8-condensation device, 21-photothermal conversion hollow fiber composite ceramic membrane. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0023] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0024] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible sub-ranges and individual values ​​within the ranges.

[0025] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0026] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0027] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0028] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0029] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0030] See also Figure 1 The present invention provides a method for preparing a photothermal conversion hollow fiber composite ceramic membrane, comprising: S1: preparing a ceramic membrane suspension; wherein, by mass percentage, the ceramic membrane suspension comprises 46% to 51.4% of coal gangue powder, 0.5% to 1% of a binder, 4% to 6% of a plasticizer, 0.5% to 1% of a dispersant and 43% to 46% of an organic solvent, specifically: First, the gangue is dried in the sun and then crushed by a crusher, the crushing time of the crusher is 60 to 240 seconds, and then the gangue powder is sieved by a 500 to 5000 mesh sieve and dried to obtain a gangue powder with a particle size of 2.6 to 25 μm; 46% to 51.4% of coal gangue powder, 0.5% to 1.3% of binder, 0.5% to 1% of dispersant and 43% to 46% of organic solvent are placed in a ball mill according to the proportion, mixed at a speed of 200 to 300 rp / min, and then 4% to 6% of plasticizer is added, and the ball milling and stirring are continued for 20 to 28 hours, and vacuum degassing is performed to obtain a ceramic membrane suspension; The grinding balls in the ball mill include grinding balls with a diameter of 15 mm and grinding balls with a diameter of 12 mm, and the mass ratio of the grinding balls with a diameter of 15 mm to the grinding balls with a diameter of 12 mm is 1:3; the binder is polyvinyl pyrrolidone, sodium carboxymethyl cellulose or hydroxypropyl methylcellulose; the organic solvent is dimethylformamide, dimethylacetamide or N-methylpyrrolidone; the plasticizer is dibutyl phthalate, dioctyl adipate or polyether sulfone; the dispersant is polyacrylic acid or polyethylene glycol; and the particle size of the coal gangue powder is 10 to 2 µm.

[0031] S2: Using the ceramic membrane suspension to prepare a ceramic membrane body, specifically: The ceramic membrane suspension is prepared into a ceramic membrane blank by a dry-wet spinning phase transfer method and then dried at room temperature; the spinneret used in the dry-wet spinning phase transfer is a single-hole spinneret with an outer diameter of 2.0 to 5.0 mm and an inner diameter of 1.0 to 2.5 mm. The flow rate of the ceramic membrane suspension is 10 to 15 mL / min, and the flow rate of pure water is 10 to 20 mL / min.

[0032] S3: calcining the ceramic membrane body to obtain a coal gangue hollow fiber ceramic membrane substrate, specifically: The ceramic membrane blank is placed in a muffle furnace and sintered at 1000° C. to 1300° C. for 150 to 240 minutes to obtain a gangue hollow fiber ceramic membrane substrate; the average pore size distribution of the gangue hollow fiber ceramic membrane substrate is 5 to 10 μm.

[0033] S4: A pyrrole-graphene oxide mixed solution is used to polymerize the surface of the ceramic membrane substrate to obtain a photothermal conversion hollow fiber composite ceramic membrane; wherein the pyrrole-graphene oxide mixed solution includes pyrrole, graphene oxide, an oxidant, and an initiator, wherein the mass concentration of graphene oxide is 0.1% to 0.4%, the mass concentration of the initiator is 0.1% to 0.7%, and the molar ratio of the oxidant to the pyrrole monomer is 50% to 100%; the oxidant is sulfuric acid, ferric chloride or hydrogen peroxide; the initiator is ammonium persulfate or potassium persulfate, specifically: The ceramic membrane substrate is immersed in a mixed solution of pyrrole, graphene oxide and initiator for 5 to 30 minutes, and then an oxidant is added to the mixed solution of pyrrole, graphene oxide and initiator to carry out polymerization reaction for 300 to 650 minutes to obtain a photothermal conversion hollow fiber composite ceramic membrane.

[0034] The present invention also provides a photothermal conversion hollow fiber composite ceramic membrane, which is prepared by the preparation method of the above-mentioned photothermal conversion hollow fiber composite ceramic membrane. Polypyrrole and graphene oxide are both photothermal conversion materials with excellent performance. Due to the two-dimensional sheet structure of graphene oxide and its rich carboxyl and hydroxyl functional groups, it can undergo a network cross-linking reaction with the amine group on the pyrrole molecule. After the pyrrole monomer is added to the graphene oxide, a three-dimensional network of capillary micro-nano laminated channels is formed through polymerization reaction, providing a large number of capillary channels, increasing the water transmission path, reducing the mass transfer resistance of water in the active layer, and helping to improve the permeation flux and evaporation efficiency of water. Therefore, a three-dimensional network of capillary micro-nano laminated channels is generated on the surface of the ceramic membrane substrate after the polymerization reaction, which is called the PPy / GO photothermal conversion active layer. The PPy / GO photothermal conversion active layer has excellent sunlight absorption capacity and photothermal conversion performance; compared with ordinary capillaries, the PPy / GO photothermal conversion active layer has significant photothermal conversion performance, which not only accelerates the heat transfer rate between the active layer and the brine, but also improves the evaporation efficiency of the brine. The prepared PPy / GO@HFCCM with uniform pore size absorbs the reverse osmosis concentrated brine into the photothermal conversion active layer through capillary action. PPy / GO@HFCCM accelerates the evaporation of water on the surface of the composite membrane under solar light with the help of the micro-nano laminated channel transmission effect, and forms distilled water after entering the condensation device through the air outlet of the ventilation system, thereby further concentrating the reverse osmosis concentrated water. It has significant capillary micro-nano laminated channel transmission performance and heat exchange effect. The special graphene oxide laminated structure of PPy / GO@HFCCM can widely absorb sunlight and achieve more efficient photothermal conversion. In addition, the three-dimensional mesh capillary micro-nano channels inside the active layer provide a larger heating area for the salt water transmitted in the active layer, which better improves the evaporation efficiency of the salt water. Moreover, the photothermal conversion active layer mixed with graphene oxide can enhance the hydrophilicity of the membrane surface, reduce the surface energy of the active layer, and quickly transmit water molecules to the membrane surface to generate water vapor. At the same time, the lower surface energy effectively avoids the nucleation of salt ion crystallization, inhibits salt aggregation, slows down the crystallization of salt in the concentrated brine, and prevents the formation of salt scale to block the membrane pores.

[0035] See also Figure 2 The present invention provides a solar thermal evaporation system, comprising a light-transmitting glass 1, a solar thermal conversion component 2, a tubular fan 3, a circulating water pump 4, a reverse osmosis concentrated water tank 5, a concentration tank 6, an evaporation crystallization device 7 and a condensation device 8; the solar thermal conversion component 2 comprises the above-mentioned photothermal conversion hollow fiber composite ceramic membrane 21; the light-transmitting glass 1 is arranged on the outside of the solar thermal conversion component 2; the tubular fan 3 is arranged on the light-transmitting glass 1; The reverse osmosis concentrated water outputted from the reverse osmosis concentrated water pool 5 enters the photothermal conversion hollow fiber composite ceramic membrane 21 in turn through the concentration pool 6 and the circulating water pump 4; the water evaporated by the photothermal conversion hollow fiber composite ceramic membrane 21 under solar radiation enters the condensation device 8 to condense into cooling water; the reverse osmosis concentrated water evaporated and concentrated by the photothermal conversion hollow fiber composite ceramic membrane 21 enters the evaporation crystallization device 7. The reverse osmosis concentrated water enters the photothermal conversion hollow fiber composite ceramic membrane 21 in the bottom pipeline of the solar photothermal conversion component 2 through the circulating water pump 4, and the water flows in a downward-inward and upward-outward direction through the solar photothermal conversion component 2 for circulation, and diffuses to the surface of the photothermal conversion hollow fiber composite ceramic membrane 21 through the capillary effect, and the water evaporates faster under the solar light with the help of the ventilation system, and the water vapor enters the condensation device 8 through the air outlet to form cooling water, thereby increasing the salt content in the reverse osmosis concentrated water and improving the concentration effect of the reverse osmosis concentrated water. When the salt content of the concentrated liquid reaches a certain concentration, the concentrated water in the circulation state is discharged into the evaporation crystallization device 7 for evaporation crystallization. This circulation process can effectively avoid the salt precipitation in the photothermal conversion hollow fiber composite ceramic membrane 21 due to excessive concentration, and the subsequent reverse osmosis concentrated water to be treated enters the next circulation evaporation concentration process. By constructing a solar photothermal conversion material with both low cost and high photothermal conversion efficiency, the purpose of low energy consumption and zero emission is achieved.

[0036] The application of the photothermal conversion hollow fiber composite ceramic membrane in water treatment as mentioned above not only realizes the environmental protection concept of "treating waste with waste" and solves the problem of high cost of coal gangue treatment, but also has the characteristics of low energy consumption, high treatment efficiency, environmental friendliness and good flexibility. It provides a sustainable solution for water treatment, which is especially suitable for the treatment of energy-shortage or high-salt and highly polluted water bodies, and generates huge economic benefits.

[0037] Example 1 The gangue was dried in the sun and then crushed by a pulverizer for 60 seconds. The gangue powder was then sieved with a 500-mesh sieve and dried to obtain a gangue powder with a particle size of 25 μm. 49.1% of coal gangue powder, 1.3% of polyvinyl pyrrolidone, 0.6% of polyethylene glycol and 43% of dimethylacetamide were placed in a ball mill according to the ratio. The grinding balls included grinding balls with a diameter of 15 mm and grinding balls with a diameter of 12 mm, and the mass ratio of grinding balls with a diameter of 15 mm to grinding balls with a diameter of 12 mm was 1:3. The ball mill speed was 250 rpm, and the suspension was stirred for 24 hours. After adding 6% dioctyl adipate, it was stirred for 24 hours. After grinding and stirring, a uniformly dispersed suspension was obtained, and a vacuum pump was used for vacuum degassing treatment. The vacuum degassing time was 30 minutes to obtain a ceramic membrane suspension. A single-hole spinneret was used, which had an outer diameter of 2 mm and an inner diameter of 1 mm. The pure water flow rate of the inner condensate was controlled at 10 mL / min, and the flow rate of the ceramic membrane suspension was 10 mL / min. The ceramic membrane suspension was squeezed into a water tank to complete the dry-wet spinning phase transfer process and obtain a ceramic membrane blank with a smooth surface.

[0038] The ceramic membrane blank was dried at room temperature, placed in a muffle furnace, and calcined at 1000° C. for 150 min to obtain a hollow fiber ceramic membrane substrate with an average pore size of 10 μm.

[0039] The ceramic membrane substrate was immersed in a mixed solution of pyrrole, graphene oxide and initiator for 5 minutes, and then an oxidant was added to the mixed solution of pyrrole, graphene oxide and initiator, and a polymerization reaction was carried out for 300 minutes to obtain a photothermal conversion hollow fiber composite ceramic membrane with an average pore size of 500nm. Among them, the initiator was ammonium persulfate, the mass concentration of ammonium persulfate was 0.1%, and the mass concentration of graphene oxide was 0.1%. The oxidant was ferric chloride, and the molar ratio of ferric chloride to pyrrole monomer was 1:1.

[0040] The PPy / GO@HFCCM was coupled to a solar thermal evaporation system with an inlet water temperature of 15°C, an inlet water flow rate of 50 mL / min, a solar illumination time of 10 h, and an evaporation flux of 2 L / . When the salinity of the reverse osmosis concentrate reached 20%, a batch of reverse osmosis concentrate with a salinity of 4% was replaced for cyclic evaporation and concentration. The results showed that the PPy / GO@HFCCM evaporated 15% of fresh water during the reverse osmosis concentrate treatment process, and the energy consumption of reverse osmosis concentrate treatment was reduced by 25%.

[0041] Example 2 The gangue was dried in the sun and then crushed by a pulverizer for 120 seconds. The gangue powder was then sieved by a 1000-mesh sieve and dried to obtain a gangue powder with a particle size of 13 μm. 49.1% of coal gangue powder, 1.3% of hydroxypropyl methylcellulose, 0.6% of polyacrylic acid and 43% of N-methylpyrrolidone were placed in a ball mill according to the ratio. The grinding balls included grinding balls with a diameter of 15 mm and grinding balls with a diameter of 12 mm, and the mass ratio of grinding balls with a diameter of 15 mm to grinding balls with a diameter of 12 mm was 1:3. The ball mill speed was 250 rpm, and the suspension was stirred for 24 hours. After adding 6% dibutyl phthalate, it was stirred for 24 hours. After grinding and stirring, a uniformly dispersed suspension was obtained, and a vacuum pump was used for vacuum degassing treatment. The vacuum degassing time was 30 minutes to obtain a ceramic membrane suspension. A single-hole spinneret was used, which had an outer diameter of 3 mm and an inner diameter of 1.5 mm. The flow rate of the inner condensate pure water was controlled to be 15 mL / min, and the flow rate of the ceramic membrane suspension was 10 mL / min. The ceramic membrane suspension was squeezed into the water tank to complete the dry-wet spinning phase transfer process and obtain a ceramic membrane blank with a smooth surface.

[0042] The ceramic membrane blank was dried at room temperature, placed in a muffle furnace, and calcined at 1100° C. for 180 min to obtain a hollow fiber ceramic membrane substrate with an average pore size of 9 μm.

[0043] The ceramic membrane substrate was immersed in a mixed solution of pyrrole, graphene oxide and initiator for 10 minutes, and then an oxidant was added to the mixed solution of pyrrole, graphene oxide and initiator, and a polymerization reaction was carried out for 400 minutes to obtain a photothermal conversion hollow fiber composite ceramic membrane with an average pore size of 400nm. Among them, the initiator was ammonium persulfate, the mass concentration of ammonium persulfate was 0.3%, and the mass concentration of graphene oxide was 0.2%. The oxidant was hydrogen peroxide, and the molar ratio of hydrogen peroxide to pyrrole monomer was 2:1.

[0044] The PPy / GO@HFCCM was coupled to a solar thermal evaporation system with an inlet water temperature of 20°C, an inlet water flow rate of 100 mL / min, a solar illumination time of 11 h, and an evaporation flux of 5 L / . When the salinity of the reverse osmosis concentrate reached 21%, a batch of reverse osmosis concentrate with a salinity of 5% was replaced for cyclic evaporation and concentration. The results showed that the PPy / GO@HFCCM evaporated 16% of fresh water during the reverse osmosis concentrate treatment process, and the energy consumption of reverse osmosis concentrate treatment was reduced by 30%.

[0045] Example 3 The gangue was dried in the sun and then crushed by a pulverizer for 180 seconds. The gangue powder was then sieved with a 2000-mesh sieve and dried to obtain a gangue powder with a particle size of 6.5 μm. 49.1% of coal gangue powder, 1.3% of sodium carboxymethyl cellulose, 0.6% of polyethylene glycol and 43% of dimethylformamide were placed in a ball mill according to the ratio. The grinding balls included grinding balls with a diameter of 15 mm and grinding balls with a diameter of 12 mm, and the mass ratio of grinding balls with a diameter of 15 mm to grinding balls with a diameter of 12 mm was 1:3. The ball mill speed was 250 rpm, and the suspension was stirred for 24 hours. After adding 6% dioctyl adipate, it was stirred for 24 hours. After grinding and stirring, a uniformly dispersed suspension was obtained, and a vacuum pump was used for vacuum degassing treatment. The vacuum degassing time was 30 minutes to obtain a ceramic membrane suspension. A single-hole spinneret was used, which had an outer diameter of 4 mm and an inner diameter of 2 mm. The pure water flow rate of the inner condensate was controlled at 20 mL / min, and the flow rate of the ceramic membrane suspension was 10 mL / min. The ceramic membrane suspension was squeezed into a water tank to complete the dry-wet spinning phase transfer process and obtain a ceramic membrane blank with a smooth surface.

[0046] The ceramic membrane blank was dried at room temperature, placed in a muffle furnace, and calcined at 1200° C. for 210 min to obtain a hollow fiber ceramic membrane substrate with an average pore size of 7 μm.

[0047] The ceramic membrane substrate was immersed in a mixed solution of pyrrole, graphene oxide and initiator for 20 minutes, and then an oxidant was added to the mixed solution of pyrrole, graphene oxide and initiator, and a polymerization reaction was carried out for 500 minutes to obtain a photothermal conversion hollow fiber composite ceramic membrane with an average pore size of 300nm. Among them, the initiator was potassium persulfate, the mass concentration of ammonium persulfate was 0.5%, and the mass concentration of graphene oxide was 0.3%. The oxidant was sulfuric acid, and the molar ratio of sulfuric acid to pyrrole monomer was 3:1.

[0048] The PPy / GO@HFCCM was coupled to a solar thermal evaporation system with an inlet water temperature of 25°C, an inlet water flow rate of 150 mL / min, a solar illumination time of 12 h, and an evaporation flux of 10 L / min. When the salinity of the reverse osmosis concentrate reached 22%, a batch of reverse osmosis concentrate with a salinity of 6% was replaced for cyclic evaporation and concentration. The results showed that the PPy / GO@HFCCM evaporated 17% of fresh water during the reverse osmosis concentrate treatment process, and the energy consumption of reverse osmosis concentrate treatment was reduced by 35%.

[0049] Example 4 The gangue was dried in the sun and then crushed by a pulverizer for 240 seconds. The gangue powder was then sieved with a 5000-mesh sieve and dried to obtain a gangue powder with a particle size of 2.6 µm. 49.1% of coal gangue powder, 1.3% of polyvinyl pyrrolidone, 0.6% of polyacrylic acid and 43% of dimethylformamide were placed in a ball mill according to the ratio. The grinding balls included grinding balls with a diameter of 15 mm and grinding balls with a diameter of 12 mm, and the mass ratio of grinding balls with a diameter of 15 mm to grinding balls with a diameter of 12 mm was 1:3. The ball mill speed was 250 rpm, and the suspension was stirred for 24 hours. After adding 6% polyethersulfone, it was stirred for 24 hours. After grinding and stirring, a uniformly dispersed suspension was obtained, and a vacuum pump was used for vacuum degassing treatment. The vacuum degassing time was 30 minutes to obtain a ceramic membrane suspension. A single-hole spinneret was used, which had an outer diameter of 5 mm and an inner diameter of 2.5 mm. The pure water flow rate of the inner condensate was controlled at 20 mL / min, and the flow rate of the ceramic membrane suspension was controlled at 15 mL / min. The ceramic membrane suspension was squeezed into a water tank to complete the dry-wet spinning phase transfer process and obtain a ceramic membrane blank with a smooth surface.

[0050] The ceramic membrane blank was dried at room temperature, placed in a muffle furnace, and calcined at 1300° C. for 240 min to obtain a hollow fiber ceramic membrane substrate with an average pore size of 5 μm.

[0051] The ceramic membrane substrate was immersed in a mixed solution of pyrrole, graphene oxide and initiator for 30 minutes, and then an oxidant was added to the mixed solution of pyrrole, graphene oxide and initiator, and the polymerization reaction was carried out for 600 minutes to obtain a photothermal conversion hollow fiber composite ceramic membrane with an average pore size of 200nm. Among them, the initiator was ammonium persulfate, the mass concentration of potassium persulfate was 0.7%, and the mass concentration of graphene oxide was 0.4%. The oxidant was sulfuric acid, and the molar ratio of sulfuric acid to pyrrole monomer was 4:1.

[0052] The PPy / GO@HFCCM was coupled to a solar thermal evaporation system with an inlet water temperature of 15°C, an inlet water flow rate of 250 mL / min, a solar illumination time of 12 h, and an evaporation flux of 15 L / min. When the salinity of the reverse osmosis concentrate reached 25%, a batch of reverse osmosis concentrate with a salinity of 7% was replaced for cyclic evaporation and concentration. The results showed that the PPy / GO@HFCCM evaporated 18% of fresh water during the reverse osmosis concentrate treatment process, and the energy consumption of reverse osmosis concentrate treatment was reduced by 40%.

[0053] Example 5 The gangue was dried in the sun and then crushed by a pulverizer for 120 seconds. The gangue powder was then sieved by a 1000-mesh sieve and dried to obtain a gangue powder with a particle size of 13 μm. 47.3% of coal gangue powder, 1% of hydroxypropyl methylcellulose, 0.7% of polyacrylic acid and 46% of N-methylpyrrolidone were placed in a ball mill according to the ratio. The grinding balls included grinding balls with a diameter of 15 mm and grinding balls with a diameter of 12 mm, and the mass ratio of grinding balls with a diameter of 15 mm to grinding balls with a diameter of 12 mm was 1:3. The ball mill speed was 250 rpm, and the suspension was stirred for 24 hours. After adding 5% dibutyl phthalate, it was stirred for 24 hours. After grinding and stirring, a uniformly dispersed suspension was obtained, and a vacuum pump was used for vacuum degassing treatment. The vacuum degassing time was 30 minutes to obtain a ceramic membrane suspension. A single-hole spinneret was used, which had an outer diameter of 3 mm and an inner diameter of 1.5 mm. The flow rate of the inner condensate pure water was controlled to be 15 mL / min, and the flow rate of the ceramic membrane suspension was 10 mL / min. The ceramic membrane suspension was squeezed into the water tank to complete the dry-wet spinning phase transfer process and obtain a ceramic membrane blank with a smooth surface.

[0054] The ceramic membrane blank was dried at room temperature, placed in a muffle furnace, and calcined at 1100° C. for 180 min to obtain a hollow fiber ceramic membrane substrate.

[0055] The ceramic membrane substrate was immersed in a mixed solution of pyrrole, graphene oxide and initiator for 10 minutes, and then an oxidant was added to the mixed solution of pyrrole, graphene oxide and initiator, and a polymerization reaction was carried out for 400 minutes to obtain a photothermal conversion hollow fiber composite ceramic membrane. Among them, the initiator is ammonium persulfate, the mass concentration of ammonium persulfate is 0.3%, and the mass concentration of graphene oxide is 0.2%. The oxidant is hydrogen peroxide, and the molar ratio of hydrogen peroxide to pyrrole monomer is 2:1.

[0056] Example 6 The gangue was dried in the sun and then crushed by a pulverizer for 120 seconds. The gangue powder was then sieved by a 1000-mesh sieve and dried to obtain a gangue powder with a particle size of 13 μm. 51.4% of coal gangue powder, 0.5% of hydroxypropyl methylcellulose, 1% of polyacrylic acid and 43% of N-methylpyrrolidone were placed in a ball mill according to the ratio. The grinding balls included grinding balls with a diameter of 15 mm and grinding balls with a diameter of 12 mm, and the mass ratio of grinding balls with a diameter of 15 mm to grinding balls with a diameter of 12 mm was 1:3. The ball mill speed was 250 rpm, and the suspension was stirred for 24 hours. After adding 4.1% of dibutyl phthalate, it was stirred for 24 hours. After grinding and stirring, a uniformly dispersed suspension was obtained, and a vacuum pump was used for vacuum degassing treatment. The vacuum degassing time was 30 minutes to obtain a ceramic membrane suspension. A single-hole spinneret was used, which had an outer diameter of 3 mm and an inner diameter of 1.5 mm. The flow rate of the inner condensate pure water was controlled to be 15 mL / min, and the flow rate of the ceramic membrane suspension was 10 mL / min. The ceramic membrane suspension was squeezed into the water tank to complete the dry-wet spinning phase transfer process and obtain a ceramic membrane blank with a smooth surface.

[0057] The ceramic membrane blank was dried at room temperature, placed in a muffle furnace, and calcined at 1100° C. for 180 min to obtain a hollow fiber ceramic membrane substrate.

[0058] The ceramic membrane substrate was immersed in a mixed solution of pyrrole, graphene oxide and initiator for 10 minutes, and then an oxidant was added to the mixed solution of pyrrole, graphene oxide and initiator, and a polymerization reaction was carried out for 400 minutes to obtain a photothermal conversion hollow fiber composite ceramic membrane. Among them, the initiator is ammonium persulfate, the mass concentration of ammonium persulfate is 0.3%, and the mass concentration of graphene oxide is 0.2%. The oxidant is hydrogen peroxide, and the molar ratio of hydrogen peroxide to pyrrole monomer is 2:1.

[0059] In summary, the present invention provides a photothermal conversion hollow fiber composite ceramic membrane, a preparation method and an application thereof, and uses coal gangue as a raw material to prepare a polypyrrole / graphene oxide hollow fiber composite membrane, i.e., a photothermal conversion hollow fiber composite ceramic membrane as a solar photothermal conversion material, and couples solar energy to drive re-concentration and reduction of reverse osmosis concentrated water, and concentrates the osmotic concentrated brine under the premise of low energy consumption, thereby greatly improving the evaporation efficiency of reverse osmosis concentrated water. Coal gangue, as a kind of solid waste, is pre-treated to prepare a hollow fiber ceramic membrane substrate, which realizes the transformation of raw materials from waste to treasure and reduces material costs. Using solar energy as a driving force for photothermal conversion can effectively avoid the high energy and high cost problems in traditional treatment methods. This new treatment method can reduce maintenance costs, realize the environmental protection concept of "zero discharge" of wastewater, and provide an efficient and sustainable solution for reverse osmosis concentrated water treatment.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. A method for preparing a photothermal conversion hollow fiber composite ceramic membrane, characterized in that: include: Prepare a ceramic membrane suspension; wherein, by mass percentage, the ceramic membrane suspension includes 46% to 51.4% of coal gangue powder, 0.5% to 1% of a binder, 4% to 6% of a plasticizer, 0.5% to 1% of a dispersant and 43% to 46% of an organic solvent; Using ceramic membrane suspension to prepare ceramic membrane green body; calcining the ceramic membrane green body to obtain a coal gangue hollow fiber ceramic membrane substrate; A photothermal conversion hollow fiber composite ceramic membrane is obtained by polymerizing the surface of a ceramic membrane substrate using a pyrrole graphene oxide mixed solution; wherein the pyrrole graphene oxide mixed solution comprises pyrrole, graphene oxide, an oxidant, and an initiator, wherein the mass concentration of graphene oxide is 0.1% to 0.4%, the mass concentration of the initiator is 0.1% to 0.7%, and the molar ratio of the oxidant to the pyrrole monomer is (1:1) to (4:1).

2. The method for preparing the photothermal conversion hollow fiber composite ceramic membrane according to claim 1, characterized in that: The binder is polyvinyl pyrrolidone, sodium carboxymethyl cellulose or hydroxypropyl methyl cellulose; the organic solvent is dimethylformamide, dimethylacetamide or N-methylpyrrolidone; the plasticizer is dibutyl phthalate, dioctyl adipate or polyether sulfone; the dispersant is polyacrylic acid or polyethylene glycol; and the particle size of the coal gangue powder is 10 to 2 µm.

3. The method for preparing the photothermal conversion hollow fiber composite ceramic membrane according to claim 1, characterized in that: The oxidant is sulfuric acid, ferric chloride or hydrogen peroxide; the initiator is ammonium persulfate or potassium persulfate.

4. The method for preparing the photothermal conversion hollow fiber composite ceramic membrane according to claim 1, characterized in that: The method for preparing the ceramic membrane suspension is: 46% to 51.4% of coal gangue powder, 0.5% to 1% of a binder, 0.5% to 1% of a dispersant and 43% to 46% of an organic solvent are placed in a ball mill according to a proportion, mixed at a speed of 200 to 300 rp / min, 4% to 6% of a plasticizer is added, ball milling and stirring are continued for 20 to 28 hours, and vacuum degassing is performed to obtain a ceramic membrane suspension; the grinding balls in the ball mill include grinding balls with a diameter of 15 mm and grinding balls with a diameter of 12 mm, and the mass ratio of the grinding balls with a diameter of 15 mm to the grinding balls with a diameter of 12 mm is 1:

3.

5. The method for preparing the photothermal conversion hollow fiber composite ceramic membrane according to claim 1, characterized in that: The method for preparing a ceramic membrane body using a ceramic membrane suspension is as follows: The ceramic membrane suspension is prepared into a ceramic membrane body by dry-wet spinning phase transfer. The outer diameter of the spinneret used for dry-wet spinning phase transfer is 2.0-5.0 mm, the inner diameter is 1.0-2.5 mm, the flow rate of the ceramic membrane suspension is 10-15 mL / min, and the flow rate of pure water is 10-20 mL / min.

6. The method for preparing the photothermal conversion hollow fiber composite ceramic membrane according to claim 1, characterized in that: The method for calcining the ceramic membrane green body to obtain the coal gangue hollow fiber ceramic membrane substrate is: The ceramic membrane blank is placed at 1000° C. to 1300° C. and sintered for 150 to 240 minutes to obtain a coal gangue hollow fiber ceramic membrane substrate.

7. The method for preparing the photothermal conversion hollow fiber composite ceramic membrane according to claim 1, characterized in that: The method of using the pyrrole graphene oxide mixed solution to polymerize the surface of the ceramic membrane substrate to obtain the photothermal conversion hollow fiber composite ceramic membrane is: The ceramic membrane substrate is immersed in a mixed solution of pyrrole, graphene oxide and initiator for 5 to 30 minutes, and then an oxidant is added to the mixed solution of pyrrole, graphene oxide and initiator to carry out polymerization reaction for 300 to 650 minutes to obtain a photothermal conversion hollow fiber composite ceramic membrane.

8. A photothermal conversion hollow fiber composite ceramic membrane, characterized in that: The photothermal conversion hollow fiber composite ceramic membrane is prepared using the preparation method of any one of claims 1 to 7.

9. A solar thermal evaporation system, characterized in that: The invention comprises a light-transmitting glass (1), a solar thermal conversion component (2), a tubular fan (3), a circulating water pump (4), a reverse osmosis concentrated water tank (5), a concentration tank (6), an evaporation crystallization device (7) and a condensation device (8); the solar thermal conversion component (2) comprises the photothermal conversion hollow fiber composite ceramic membrane (21) according to claim 8; the light-transmitting glass (1) is arranged on the outside of the solar thermal conversion component (2); and the tubular fan (3) is arranged on the light-transmitting glass (1); The reverse osmosis concentrated water output from the reverse osmosis concentrated water pool (5) enters the photothermal conversion hollow fiber composite ceramic membrane (21) through the concentration pool (6) and the circulating water pump (4) in sequence; water evaporated by the photothermal conversion hollow fiber composite ceramic membrane (21) through solar radiation enters the condensation device (8) to be condensed to form cooling water; and the reverse osmosis concentrated water evaporated and concentrated by the photothermal conversion hollow fiber composite ceramic membrane (21) enters the evaporation crystallization device (7).

10. Use of the photothermal conversion hollow fiber composite ceramic membrane as claimed in claim 8 in water treatment.

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