Preparation method and application of a high-strength, high-performance and renewable multifunctional filter membrane

Abstract

The present invention discloses a preparation method and application of a high-strength, high-performance, and renewable multifunctional filter membrane. The preparation method of the calcium silicate-coated glass fiber fabric multifunctional filter membrane comprises the following steps: providing a glass fiber fabric; pretreating the glass fiber fabric to obtain a surface-activated glass fiber fabric; and fully soaking the surface-activated glass fiber fabric in an aqueous solution of calcium salt, ammonium chloride, and ammonia water, and allowing the mixed system to react fully at 100°C to 200°C to obtain the required calcium silicate-coated glass fiber fabric multifunctional filter membrane. It can be seen from the data in the specification that the calcium silicate-coated glass fiber fabric water purification material prepared by this preparation method of the calcium silicate-coated glass fiber fabric filter membrane can better achieve the purification of various pollutants such as oil-containing waste emulsion, fluorine, and phosphorus, and has broad application prospects in the field of low-cost and high-efficiency purification of complex sewage.

Description

Technical Field

[0001] The present invention relates to a preparation method of a filter membrane and its application, and in particular to a preparation method and application of a high-strength, high-performance, renewable and multifunctional filter membrane that can be used for one-step purification of oil-in-water emulsion, fluorine pollutants and phosphorus pollutants in sewage, belonging to the technical field of preparation of nanomaterials and environmental materials. Background Art

[0002] It is necessary to obtain clean and safe water from sewage, and the purification of complex oil-containing wastewater has triggered a research boom. The difficulty in treating oil-containing wastewater lies in the complexity and diversity of pollutants in water and the uncertainty of components. For example, during the extraction, transportation and processing of oil, a large number of emulsified oil droplets with sizes between a few nanometers and a few micrometers are generally generated. To achieve the purpose of purification, it is necessary to quickly and effectively remove these tiny oil droplets in the emulsified wastewater. At present, filtration separation technologies with adjustable shape, size and thickness have been widely used in the treatment of oil-containing wastewater. However, the large-scale application of filtration separation materials is still restricted by many factors, such as complex manufacturing processes, poor stability, low strength, small flux, short service life, and difficulty in simultaneously achieving high separation flux and separation efficiency. Therefore, there is an urgent need to develop a new type of filter material for efficient purification of oil-containing wastewater.

[0003] With the development of modern industry, a large amount of high-concentration industrial wastewater containing fluorine has been discharged. These wastewaters generally contain fluorine in the form of fluoride ions. Many enterprises do not have perfect treatment facilities to treat these wastewaters, resulting in the fluorine content in the discharged wastewater exceeding the national discharge standard, seriously polluting the environment and threatening people's physical health. In addition, there is also phosphorus-containing sewage from domestic sewage, biochemical pharmaceuticals, metal surface treatment, factory and livestock wastewater, and fertilizer loss in mountain forests and cultivated land. Phosphorus is a key nutrient causing water eutrophication. Water eutrophication will not only cause the rapid growth of algae in water, but also cause a sharp drop in the oxygen content of the water, affecting the survival of aquatic organisms such as fish. Therefore, the coexistence of harmful pollutants such as oil and surfactants, fluorine and phosphorus in sewage further increases the purification difficulty of such wastewaters. In the process of treating oil-containing wastewater by filtration separation technology, it is necessary to not only separate stable oil-water emulsions, but also remove a small amount of harmful pollutants such as fluorine and phosphorus in the water. Therefore, designing a multifunctional filter material should simultaneously achieve the separation of oil-water emulsions and the removal of harmful pollutants such as fluorine and phosphorus in the wastewater, which is very important for the treatment of oil-containing sewage.

[0004] As a commonly used engineering material, fiberglass fabric has excellent mechanical strength, corrosion resistance, and high-temperature resistance. Using fiberglass fabric as a substrate, separation materials suitable for harsh environments can be prepared to meet the requirements for high mechanical strength, high flux, and efficient filtration materials in the actual oil-water separation process. At the same time, a more stable inorganic coating can be easily constructed on the surface of fiberglass fabric, making it more suitable for use in extreme environments. Calcium silicate is an environmentally friendly material with excellent adsorption properties. It can grow in different matrices or be wrapped on other matrices to form composite materials with nano-layers, nano-flowers, and other morphologies. Hydrophilic calcium silicate with a special surface structure has a super-hydrophilic - underwater super-oleophobic interface, enabling efficient oil-water separation.

[0005] However, there is currently no relevant report on the preparation of calcium silicate-coated water purification materials based on fiberglass fabric, nor is there a precedent for application. Summary of the Invention

[0006] The object of the present invention is to provide a multifunctional filter membrane with high strength, high performance, and renewability.

[0007] Another object of the present invention is to provide a preparation method for a multifunctional filter membrane with high strength, high performance, and renewability.

[0008] Another object of the present invention is to provide the application of the high-strength, high-performance, and renewable multifunctional filter membrane in purifying sewage.

[0009] I. Preparation of Multifunctional Filter Membrane Based on Fiberglass Fabric

[0010] The preparation method of the high-strength, high-performance, and renewable multifunctional filter membrane of the present invention includes the following steps:

[0011] (1) Immerse the fiberglass fabric in an ethanol aqueous solution and stir thoroughly until there are no other impurities on the surface of the fiberglass fabric, and then dry to obtain a clean fiberglass fabric with no impurities on the surface;

[0012] The diameter range of the fiberglass fabric is 0.1 - 0.3 mm, and the concentration of the ethanol aqueous solution is 5% - 60%.

[0013] (2) Add an alkaline solution to the clean fiberglass fabric with no impurities on the surface, soak it thoroughly to activate the surface to generate more silanol groups, wash it to neutrality, and then dry to obtain a surface-activated fiberglass fabric;

[0014] The solute of the alkaline solution is at least one of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium silicate, and potassium bicarbonate. The mass concentration of the alkaline solution is 2% - 60%, the reaction temperature is 10 - 60 °C, and the reaction time is 2 - 8 h.

[0015] (3) Immerse the surface-activated glass fiber fabric in a mixed solution of calcium salt, ammonium chloride, ammonia water and water, and react fully at 100 - 200 °C for 1 - 12 h to obtain a glass fiber fabric water purification material with a calcium silicate nanolayer coated on its surface.

[0016] The calcium salt is at least one of calcium chloride, calcium nitrate, calcium acetate, calcium dihydrogen phosphate, calcium bicarbonate, calcium citrate, calcium gluconate, calcium bisulfate, calcium bisulfite, calcium hypochlorite, calcium bromide, calcium iodide, calcium chlorate, calcium perchlorate, and the molar concentration of the calcium salt in the mixed solution is 0.1 - 10 mol / L. The mass ratio of the calcium salt to ammonium chloride is 1:5 - 50. The mass ratio of the calcium salt to ammonia water is 1:10 - 100.

[0017] The mass ratio of the surface-activated glass fiber fabric to the synthesized calcium silicate nanolayer is 10 - 1000:1 - 10.

[0018] First, the glass fiber fabric is placed in an alkaline solution for activation to generate silanol groups on the surface of the glass fiber. Subsequently, the silanol groups react with calcium ions in an alkaline environment to coat a layer of calcium silicate nanostructure on the surface of the glass fiber, endowing it with superhydrophilic - underwater superoleophobic properties, efficiently realizing oil - water separation, and simultaneously enhancing the adsorption capacity of the composite material for fluorine and phosphorus.

[0019] II. Structure and properties of the glass fiber fabric - based multifunctional filter membrane

[0020] (1) Place a one - square - meter glass fiber fabric with a fiber diameter of 0.1 mm in a 5 wt% ethanol aqueous solution for thorough cleaning and then dry it; (2) Immerse the glass fiber fabric obtained in step (1) in 5 L of a 2 wt% sodium hydroxide aqueous solution for full wetting, react fully at 20 °C for 8 h, wash it with water and then dry it to obtain the required surface - activated glass fiber fabric; (3) Immerse the surface - activated glass fiber fabric obtained in step (2) fully in 5 L of an aqueous solution containing 0.1%, 2% and 2.5% of calcium chloride, ammonium chloride and ammonia water respectively, react at 200 °C for 2 h, wash it with water more than three times and then dry it to obtain the required multifunctional filter membrane based on calcium silicate - coated glass fiber fabric.

[0021] Structure characterization: Conduct surface scanning electron microscopy observation on the calcium silicate - coated glass fiber fabric water purification material obtained in Example 1 to obtain Figure 2 a~ Figure 2 b.

[0022] From Figure 2 a~ Figure 2 b, it can be seen that after calcium silicate coating, the surface morphology of the fabric has changed significantly, and a dense calcium silicate coating layer is wrapped on the fabric surface.

[0023] Performance Evaluation:

[0024] 1. Mechanical Property Test

[0025] As Figure 3 shown, after applying a weight of 4 kg, the surface structure of the fabric is not damaged, indicating that the calcium silicate-coated glass fiber fabric has very high mechanical strength, and the tensile strength is greater than 65 MPa.

[0026] 2. Wettability Test

[0027] The wettability of the filter membrane surface is crucial in sewage treatment. Conducting an underwater oil contact angle test on the calcium silicate-coated glass fiber fabric-based multifunctional filter membrane is an effective means to test the wettability of the filter membrane. The results are as Figure 4 shown.

[0028] As Figure 4 can be seen, the underwater oil contact angle of this multifunctional filter membrane is 155.5°, indicating that the prepared multifunctional filter membrane has underwater superoleophobicity and has the wettability basis for separating oil-water mixtures.

[0029] 3. Recyclability Test

[0030] As Figure 5 can be seen, after the surface coating layer of this multifunctional filter membrane is removed by friction, it can be repeatedly coated by reacting again. The regenerated multifunctional filter membrane still has underwater oleophobicity. The underwater oil contact angle of the regenerated multifunctional filter membrane is 155.4°, which does not change much from that of the multifunctional filter membrane prepared for the first time, indicating that the prepared multifunctional filter membrane has recyclability.

[0031] III. Water Treatment Research on Glass Fiber Fabric-based Multifunctional Filter Membrane

[0032] 1. Water-in-Oil Emulsion Separation Performance Test

[0033] Conducting simulated separation tests on the above-prepared glass fiber fabric-based multifunctional filter membrane under different oil-in-water emulsions. The results are as Figure 6 and 7 shown.

[0034] As Figure 6 can be seen, this glass fiber fabric-based multifunctional filter membrane has good separation effects for various oil-in-water emulsions such as gasoline / water emulsion and soybean oil / water emulsion, and the separation efficiency reaches 100%.

[0035] As Figure 7It can be seen that the glass fiber fabric-based multifunctional filter membrane has the highest flux (9500 LHM) for gasoline / water emulsion and the lowest flux (6500 LHM) for kerosene / water emulsion. Generally speaking, the separation flux of the glass fiber fabric-based multifunctional filter membrane is between 6000 and 10000 LHM, indicating that the calcium silicate-coated glass fiber fabric prepared by the present invention has excellent separation effects on various oil-in-water emulsions.

[0036] Subsequently, the glass fiber fabric-based multifunctional filter membrane was tested with real oily sewage. The sewage used for the test was real oily emulsion sewage from a seriously polluted river, which contained various organic pollutants such as hydrocarbons, lipids, aliphatics, aromatics, waxes, as well as phenols, naphthalenes, amines, benzenes, kerosene, etc. (as shown in Figure 8 a). The test results are as shown in Figure 8 b.

[0037] Comparing Figure 8 a and Figure 8 b, it can be seen that the oily emulsion was completely separated, and the oil removal rate was higher than 99.9%.

[0038] This shows that the calcium silicate-coated glass fiber fabric prepared by the present invention has good separation effects on oily emulsion sewage and meets the expected goals.

[0039] 2. Pollutant removal test

[0040] The sewage containing fluoride ions with different concentrations was filtered through the multifunctional filter membrane of the calcium silicate-coated glass fiber fabric prepared above. The results are as shown in Figure 9 . It can be seen from Figure 9 that the multifunctional filter membrane of the above calcium silicate-coated glass fiber fabric has a high removal rate of up to 99.9% for sewage with a fluoride ion concentration of 50 mg / L, and the filtering effect is good.

[0041] The sewage containing phosphate ions (the concentration of potassium dihydrogen phosphate is 50 mg / L) was filtered through the multifunctional filter membrane of the calcium silicate-coated glass fiber fabric prepared above. The results are as shown in Figure 10 . It can be seen from Figure 10 that after being filtered through the multifunctional filter membrane of the calcium silicate-coated glass fiber fabric, the phosphate ions in the water have been completely removed, and the removal rate is as high as 99.9%.

[0042] In summary, the present invention has the following advantages:

[0043] (1) The present invention uses a high-strength glass fiber fabric as the matrix material to prepare a calcium silicate-coated glass fiber fabric water purification material, which has multiple advantages such as high mechanical strength, high flux, high efficiency, strong corrosion resistance, impact resistance, and high temperature resistance;

[0044] (2) The preparation method of the calcium silicate-coated glass fiber fabric water purification material of the present invention has a simple process and does not require complex equipment. Water is used as the solvent in the material preparation process, and no toxic or harmful organic solvents and surfactants are used, so the process is relatively green and environmentally friendly;

[0045] (3) The complex micro-nano structure on the surface of the calcium silicate coating endows it with superhydrophilic-underwater superoleophobic properties, having an efficient oil-water separation effect. At the same time, the calcium silicate coated on the surface enhances the adsorption performance of the composite material for fluorine and phosphorus;

[0046] (4) The silicon dioxide of the glass fiber fabric itself is in-situ transformed into calcium silicate by epitaxial growth to achieve the coating of the glass fiber fabric. Therefore, the waste filter layer that has filtered and adsorbed fluorine and phosphorus can be reused and is easy to reconstruct, having the advantage of being renewable. Description of the Drawings

[0047] Figure 1 It is the preparation flow chart of the multifunctional filter membrane of the present invention,

[0048] Figure 2 It is the scanning electron microscope image of the multifunctional filter membrane of the present invention,

[0049] Figure 3 It is the mechanical property test diagram of the multifunctional filter membrane of the present invention,

[0050] Figure 4 It is the schematic diagram of the underwater oil contact angle of the multifunctional filter membrane of the present invention,

[0051] Figure 5 It is the schematic diagram of the regeneration process of the multifunctional filter membrane of the present invention and the schematic diagram of the underwater oil contact angle of the regenerated functional filter membrane,

[0052] Figure 6 It is the column chart of the separation efficiency of the multifunctional filter membrane of the present invention for different oil-in-water emulsions,

[0053] Figure 7 It is the column chart of the separation flux of the multifunctional filter membrane of the present invention for different oil-in-water emulsions,

[0054] Figure 8 a is the microscopic photo of the real oil-in-water emulsion sewage, Figure 8 b is the microscopic photo of the real oil-containing sewage after filtration with the multifunctional filter membrane of the present invention;

[0055] Figure 9 It is the schematic diagram of the removal rate of fluoride ions in different concentrations of fluoride-containing sewage by the multifunctional filter membrane of the present invention,

[0056] Figure 10 It is the absorbance comparison diagram of the multifunctional filter membrane of the present invention before and after filtering the phosphorus-containing sewage. Specific Embodiments

[0057] The present invention will be further explained and illustrated below in conjunction with specific embodiments.

[0058] Example 1

[0059] (1) Thoroughly wash a 5-square-meter fiberglass fabric with a fiber diameter of 0.15 mm in an aqueous ethanol solution of 15 wt% and then dry it; (2) Thoroughly soak the fiberglass fabric obtained in step (1) in 5 L of an aqueous potassium hydroxide solution with a concentration of 60 wt%, fully react at 60°C for 2 h, wash with water and then dry to obtain the required pretreated surface-activated fiberglass fabric; (3) Thoroughly immerse the surface-activated fiberglass fabric obtained in step (2) in 5 L of an aqueous solution containing calcium nitrate, ammonium chloride, and ammonia water with concentrations of 10%, 2.5%, and 0.5% respectively. The above mixed system reacts at 100°C for 8 h respectively, washes with water more than three times and then dries to obtain the required calcium silicate-coated fiberglass fabric-based multifunctional filter membrane. Serial number: CaSi@Gf-1.

[0060] Example 2

[0061] (1) Thoroughly wash a 2-square-meter fiberglass fabric with a fiber diameter of 0.2 mm in an aqueous ethanol solution of 25 wt% and then dry it; (2) Thoroughly soak the fiberglass fabric obtained in step (1) in 5 L of an aqueous potassium carbonate solution with a concentration of 40 wt%, fully react at 20°C for 6 h, wash with water and then dry to obtain the required pretreated surface-activated fiberglass fabric; (3) Thoroughly immerse the surface-activated fiberglass fabric obtained in step (2) in 5 L of an aqueous solution containing calcium acetate, ammonium chloride, and ammonia water with concentrations of 2.5%, 0.5%, and 5% respectively. The above mixed system reacts at 150°C for 5 h respectively, washes with water more than three times and then dries to obtain the required calcium silicate-coated fiberglass fabric-based multifunctional filter membrane. Serial number: CaSi@Gf-1.

[0062] Example 3

[0063] (1) Thoroughly wash 3 square meters of fiberglass fabric with a fiber diameter of 0.24 mm in an aqueous ethanol solution of 50 wt% and dry it; (2) Thoroughly soak the fiberglass fabric obtained in step 1 in 5 L of an aqueous sodium hydrogen carbonate solution with a concentration of 30 wt%, react fully at 20 °C for 4 h, wash with water and then dry to obtain the required pretreated surface-activated fiberglass fabric; (3) Thoroughly immerse the surface-activated fiberglass fabric obtained in step 2 in 5 L of an aqueous solution containing calcium dihydrogen phosphate, ammonium chloride, and ammonia water with concentrations of 3%, 2%, and 1% respectively. The above mixed system reacts at 170 °C for 5 h respectively, wash with water more than three times and then dry to obtain the required calcium silicate-coated fiberglass fabric-based multifunctional filter membrane. The material number is: CaSi@Gf-3.

[0064] Example 4

[0065] (1) Thoroughly wash 1 square meter of fiberglass fabric with a fiber diameter of 0.12 mm in an aqueous ethanol solution of 60 wt% and dry it; (2) Thoroughly soak the fiberglass fabric obtained in step 1 in 5 L of an aqueous potassium hydrogen carbonate solution with a concentration of 35 wt%, react fully at 30 °C for 7 h, wash with water and then dry to obtain the required pretreated surface-activated fiberglass fabric; (3) Thoroughly immerse the surface-activated fiberglass fabric obtained in step 2 in 5 L of an aqueous solution containing calcium bisulfate, ammonium chloride, and ammonia water with concentrations of 1%, 1%, and 2% respectively. The above mixed system reacts at 135 °C for 2.5 h respectively, wash with water more than three times and then dry to obtain the required calcium silicate-coated fiberglass fabric-based multifunctional filter membrane. The number is: CaSi@Gf-4.

Claims

1. A preparation method of a high-strength, high-performance, renewable and multifunctional filter membrane, characterized in that, It includes the following steps: 1) Immerse the glass fiber fabric in an ethanol aqueous solution and stir thoroughly until there are no other impurities on the surface of the glass fiber fabric, and then dry it to obtain a clean glass fiber fabric with no impurities on the surface; 2) Add an alkaline solution to the clean glass fiber fabric with no impurities on the surface, immerse it thoroughly to activate the surface to generate more silanol groups, wash it to neutrality and then dry it to obtain a surface-activated glass fiber fabric; 3) Immerse the surface-activated glass fiber fabric in a mixed solution of calcium salt, ammonium chloride, ammonia water and water, and react fully at 100 - 200 °C for 1 - 12 h to obtain a glass fiber fabric water purification material with a calcium silicate nanolayer coated on the surface.

2. The preparation method of a high-strength, high-performance, renewable multifunctional filter membrane according to claim 1, wherein: The diameter range of the glass fiber fabric is 0.1 - 0.3 mm.

3. The preparation method of a high-strength, high-performance, renewable and multifunctional filter membrane according to claim 1, characterized in that: The concentration of the ethanol aqueous solution is 5% - 60%.

4. The preparation method of a high-strength, high-performance, renewable multifunctional filter membrane according to claim 1, characterized in that: The solute of the alkaline solution is at least one of potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium silicate and potassium bicarbonate. The mass concentration of the alkaline solution is 2% - 60%, the reaction temperature is 10 - 60 °C, and the reaction time is 2 - 8 h.

5. The preparation method of a high-strength, high-performance, renewable and multifunctional filter membrane according to claim 1, characterized in that: The calcium salt is at least one of calcium chloride, calcium nitrate, calcium acetate, calcium dihydrogen phosphate, calcium bicarbonate, calcium citrate, calcium gluconate, calcium bisulfate, calcium bisulfite, calcium hypochlorite, calcium bromide, calcium iodide, calcium chlorate and calcium perchlorate. The molar concentration of the calcium salt in the mixed solution is 0.1 - 10 mol / L.

6. The preparation method of a high-strength, high-performance, renewable multifunctional filter membrane according to claim 1, characterized in that: The mass ratio of the calcium salt to ammonium chloride is 1:5 - 50.

7. The preparation method of a high-strength, high-performance, renewable multifunctional filter membrane according to claim 1, characterized in that: The mass ratio of the calcium salt to ammonia water is 1:10 - 100.

8. The preparation method of a high-strength, high-performance, renewable multifunctional filter membrane according to claim 1, characterized in that: The mass ratio of the surface-activated glass fiber fabric to the synthesized calcium silicate nanolayer is 10 - 1000:1 - 10.

9. A multifunctional filter membrane of calcium silicate-coated glass fiber fabric prepared by the method according to claim 1.

10. Application of a multifunctional filter membrane of calcium silicate-coated glass fiber fabric prepared by the method according to claim 1 in sewage treatment.

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