A modified filter paper with high water removal efficiency and a modification method and application thereof

Abstract

The application provides a modified filter paper with high water removal efficiency and a modification method and application thereof. The modification method comprises the following steps: uniformly mixing a main modifier, an auxiliary modifier and water to obtain a modification liquid; the main modifier is a water-soluble polymer rich in hydrogen bond combination sites; the auxiliary modifier is a small molecule hydrogen bond breaker; a silane coupling agent is used to modify and pretreat the surface of a hydrophilic layer of a filter paper substrate; the modification liquid is coated on the surface of the hydrophilic layer of the filter paper substrate after the modification pretreatment, and the filter paper substrate is left to stand until the modification liquid is fully spread, and then the modified filter paper is obtained after drying. The present application upgrades the existing single physical layered filtration technology to a composite mode of chemical competitive adsorption-physical filtration, builds competitive combination sites on the filter paper which can actively destroy the combined water in diesel oil, realizes efficient deconstruction of the combined water and enables the combined water to be removed by the existing physical method. When the modified filter paper is used for biodiesel oil-water separation, the removal rate of the combined water is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of oil-water separation materials technology, specifically to a modified filter paper for high-efficiency water removal, its modification method, and its application. Background Technology

[0002] Biodiesel is a monoalkyl fatty acid ester obtained from animal and vegetable oils and alcohols through transesterification. As a cheaper and cleaner renewable energy source than conventional diesel, it has attracted widespread attention. It can be used directly as fuel and as a raw material for various high-value products, thus possessing high commercial benefits and application prospects. However, biodiesel contains a large amount of unsaturated high-carbon-chain fatty acid methyl esters, making it susceptible to moisture residue during production and storage due to factors such as introduction from raw materials, reaction formation, or environmental moisture absorption. This moisture not only leads to incomplete combustion, increasing harmful gas emissions and polluting the environment, but more importantly, it reduces the lubricating properties of the diesel, accelerating wear on fuel tanks and engine components, and even damaging the engine. Furthermore, rust and corrosion in the fuel tank can further generate hard particles, which are transported with the fuel, causing engine wear and significantly impacting safety, fuel economy, and engine lifespan.

[0003] Moisture exists in biodiesel in three forms: emulsified water, free water, and bound water. Emulsified water (particle size around 20 μm) and free water are easily separated and recovered using conventional filters. However, bound water (dissolved water) forms stable intermolecular interactions with biodiesel molecules, making it difficult to remove using existing processes (traditional physical / chemical methods). Nevertheless, residual bound water still accelerates the oxidation and deterioration of biodiesel, corrodes the engine and piping systems, and reduces combustion efficiency.

[0004] Existing filters employ a multi-layer composite filter paper structure consisting of a hydrophilic water-collecting layer and a water-repellent layer. The hydrophilic layer collects water droplets into larger particles, which are then blocked by the water-repellent layer, achieving initial removal of free water. However, this water removal technology relies entirely on physical filtration, is only effective for free water in its free state, and allows a large amount of chemically bound water to penetrate the filter paper and enter the biofuel. Therefore, the existing method has very limited effectiveness in removing bound water and cannot meet the high moisture control requirements of biodiesel. Filters using this traditional structure often experience a sharp decrease in filter element lifespan and oil-water separation efficiency far below the nominal value when using biodiesel. This not only increases maintenance costs for users but also, due to the increased failure rate of the fuel system, to some extent restricts the widespread application of biodiesel as a clean energy source.

[0005] Therefore, how to effectively remove bound water from biodiesel and improve the adsorption and separation capacity of filter paper for bound water has become a key issue that urgently needs to be addressed in the current filter technology field. Summary of the Invention

[0006] In view of the technical problems existing in the background art, the present invention provides a modified filter paper for efficient water removal, a modification method thereon and its application, aiming to solve the technical problem that filter paper in the prior art cannot effectively remove bound water from biodiesel.

[0007] In a first aspect, the present invention provides a method for modifying filter paper for high-efficiency water removal, comprising the following steps: S1. The main modifier and auxiliary modifier are mixed evenly with water to obtain a modified solution; the main modifier is a water-soluble polymer rich in hydrogen bond binding sites; the auxiliary modifier is a small molecule hydrogen bond disruptor. S2. The surface of the hydrophilic layer of the filter paper substrate is modified and pretreated using a silane coupling agent; S3. The modified liquid is coated onto the hydrophilic layer surface of the pretreated filter paper substrate, left to stand until the modified liquid is fully spread, and then dried to obtain the modified filter paper.

[0008] Preferably, the main modifier includes at least one of polyethylene glycol diglycidyl ether, polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, polyacrylamide, polysaccharide, and polyethyleneimine.

[0009] Preferably, the auxiliary modifier includes at least one of lithium bromide, lithium chloride, urea, and guanidine hydrochloride.

[0010] Preferably, the mass ratio of the primary modifier to the secondary modifier is (5~40):1.

[0011] Preferably, the total concentration of the main modifier and auxiliary modifier in the modified solution is 0.1wt%~10wt%.

[0012] Preferably, the modification pretreatment specifically includes the following steps: spraying a silane coupling agent solution onto the hydrophilic layer surface of the filter paper substrate and drying it.

[0013] Preferably, the concentration of the silane coupling agent solution is 1wt%~5wt%; the spraying amount of the silane coupling agent solution is 15~60mL / m. 2 The drying temperature is 50~100℃, and the drying time is 5~30 minutes.

[0014] Preferably, in step S3, the coating amount of the modified liquid is 10~100mL / m 2 The resting time is 20-60 minutes; the drying temperature is 50-100℃, and the drying time is 5-30 minutes.

[0015] In a second aspect, the present invention provides a modified filter paper for high-efficiency water removal, which is prepared by the modification method described in the first aspect.

[0016] Thirdly, the present invention provides an application of a modified filter paper with high efficiency in water removal in the oil-water separation of biodiesel.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention modifies the surface of filter paper by designing functional coatings, upgrading the existing single physical layered filtration technology to a composite mode of chemical competitive adsorption-physical filtration. It constructs competitive binding sites on the filter paper that can actively destroy the bound water in diesel, thereby achieving efficient deconstruction of the bound water and enabling it to be filtered and removed by existing physical methods.

[0018] The modified filter paper for high-efficiency water removal provided by this invention breaks through the bottleneck of bound water removal, achieving comprehensive coverage of three forms of water: free water, emulsified water, and bound water. It fundamentally solves the technical problem that existing technologies are powerless against bound water, can meet the high standards of biodiesel, and ensure the safe operation of engines. Detailed Implementation

[0019] The embodiments of the technical solution of the present invention will be described in detail below. These embodiments are only used to illustrate the technical solution of the present invention more clearly, and are therefore merely examples and should not be used to limit the scope of protection of the present invention.

[0020] To address the technical problem that existing filter paper cannot effectively remove bound water from biodiesel, this invention provides a modified filter paper for efficient water removal, along with its modification method and application. Without altering the existing basic structure of "hydrophilic layer + hydrophobic layer," "competitive binding sites" are introduced on the surface of its hydrophilic layer, fundamentally breaking the stable system of bound water and achieving efficient separation and removal of bound water.

[0021] In a first aspect, embodiments of the present invention provide a method for modifying filter paper for high-efficiency water removal, comprising the following steps: S1. The main modifier and auxiliary modifier are mixed evenly with water to obtain a modified solution; the main modifier is a water-soluble polymer rich in hydrogen bond binding sites; the auxiliary modifier is a small molecule hydrogen bond disruptor. S2. The surface of the hydrophilic layer of the filter paper substrate is modified and pretreated using a silane coupling agent; S3. The modified liquid is coated onto the hydrophilic layer surface of the pretreated filter paper substrate, left to stand until the modified liquid is fully spread, and then dried to obtain the modified filter paper.

[0022] In the technical solution of this invention, the mechanism of action of the modified liquid components is as follows: (1) The main modifier is a long chain of macromolecules rich in hydrogen bond binding sites. It competitively snatches the bound water in biodiesel through more and stronger binding ability to form a more stable hydrogen bond effect; (2) The auxiliary modifier is a small molecule hydrogen bond disruptor. It has a super strong hydrogen bond snatching ability and is evenly distributed in the macromolecular network as a reinforcing unit. It forms a local enhancement effect in the large area of ​​competitive binding sites and can also efficiently destroy the bound water sites in biodiesel and break the original binding; (3) The main modifier and the auxiliary modifier work together to form a composite structure with macromolecules as the main body and some small molecules as the reinforcing points, which ensures the efficiency of the competitive binding mechanism, the modification effect of the filter paper and the performance stability through dual action. The modification method provided by the present invention first uses a silane coupling agent to perform surface modification treatment on the hydrophilic water-polymerizing layer of the original filter paper to form a large number of binding sites on the surface of the filter paper to ensure the access of the modifier. Then, the modification liquid is coated on the surface of the modified filter paper and dried.

[0023] Furthermore, in some embodiments, the primary modifier includes at least one of polyethylene glycol diglycidyl ether (PEGDGE), polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyacrylamide (PAAM), polysaccharide, and polyethyleneimine (PEI).

[0024] Furthermore, in some embodiments, the auxiliary modifier includes at least one of lithium bromide (LiBr), lithium chloride (LiCl), urea, and guanidine hydrochloride.

[0025] Furthermore, in some embodiments, the mass ratio of the primary modifier to the secondary modifier is (5~40):1.

[0026] Furthermore, in some embodiments, the total concentration of the primary modifier and the secondary modifier in the modified liquid is 0.1wt% to 10wt%.

[0027] Furthermore, in some embodiments, the silane coupling agent includes γ-aminopropyltriethoxysilane (KH550).

[0028] Furthermore, in some embodiments, the modification pretreatment specifically includes the following steps: spraying a silane coupling agent solution onto the hydrophilic layer surface of the filter paper substrate and drying it.

[0029] Furthermore, in some embodiments, the concentration of the silane coupling agent solution is 1wt%~5wt%; the spraying amount of the silane coupling agent solution is 15~60mL / m. 2 The drying temperature is 50~100℃, and the drying time is 5~30 minutes.

[0030] Furthermore, in some embodiments, in step S3, the coating amount of the modified liquid is 10~100mL / m 2 The resting time is 20-60 minutes; the drying temperature is 50-100℃, and the drying time is 5-30 minutes.

[0031] Secondly, embodiments of the present invention provide a modified filter paper for high-efficiency water removal, which is prepared by the modification method described in the first aspect.

[0032] In the technical solution of this invention, the modified filter paper for high-efficiency water removal obtained by this invention does not change the basic structural material system and production process of the existing filter's "water-gathering layer + water-repellent layer," but only introduces a functional modifier on the surface of the hydrophilic water-gathering layer of the filter paper. This modifier has a high density of competitive hydrogen bond sites, which can form stronger hydrogen bonds with water molecules in the water-bound system of biodiesel, thereby "stealing" water molecules from the original hydrogen bond network and transforming them from a bound state to a free state or a weakly bound state. The released water molecules can then be captured by the water-gathering layer, aggregate into large water droplets, and then separated according to the separation principle of traditional filters—through physical barrier by the water-repellent layer.

[0033] Thirdly, embodiments of the present invention provide an application of a modified filter paper with high efficiency in water removal in the separation of oil and water in biodiesel.

[0034] In the technical solution of this invention embodiment, the modified filter paper for high-efficiency water removal plays a dual synergistic role in the oil-water separation process through a combination of "chemical competitive transformation + physical coalescence interception": when biodiesel containing bound water flows through the modified filter paper, the functional groups on the filter layer surface compete with biodiesel molecules for bound water molecules. Because the binding force between the functional groups and water (such as stronger hydrogen bonding) is significantly stronger than the binding force between biodiesel and water, the bound water molecules are "snatched" from the biodiesel, accumulating and coalescing into tiny free water droplets on the filter layer surface. Subsequently, these "released" and coalesced tiny water droplets are effectively intercepted and separated when flowing through the downstream water-repellent layer, thereby achieving deep removal of bound water.

[0035] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0036] In the following embodiments of the present invention, the filter paper used is the filter paper in ordinary commercial oil filters (imported phenolic resin thermosetting paper).

[0037] Example 1 A method for modifying filter paper, the specific steps of which are as follows: (1) Preparation of modified solution: Take 45g of polyethylene glycol diglycidyl ether (PEGDGE) and add it to 200g of deionized water. Stir at 25℃ for 10 minutes until completely dissolved. Add 5g of LiBr and stir until completely dissolved. Mix it evenly and dilute with water to a total volume of 2500g to obtain a modified solution with a concentration of 2wt%.

[0038] (2) Filter paper pretreatment: Dissolve KH550 (γ-aminopropyltriethoxysilane) in ethanol solution to prepare a 2wt% solution, and spray it evenly (spraying amount is 30mL / m). 2 On the hydrophilic layer surface of the filter paper, dry at 60°C for 5 minutes to form a surface ready for grafting.

[0039] (3) Filter paper modification treatment: Spray the modified liquid obtained in step (1) (spraying amount is 15mL / m) 2 Apply the modified filter paper to the hydrophilic layer surface of the filter paper after step (2), and then let it stand at room temperature for 30 minutes to allow it to spread fully; put it in a 60℃ oven to dry for 10 minutes to obtain the modified filter paper.

[0040] Example 2 A method for modifying filter paper, the specific steps of which are as follows: (1) Preparation of modified solution: Take 36 g of polyvinylpyrrolidone (PVP) and add it to 200 g of deionized water. Stir at 25°C for 10 minutes until completely dissolved. Add 4 g of LiCl and stir until completely dissolved. Mix it evenly and dilute with water to a total volume of 2667 g to obtain a modified solution with a concentration of 1.5 wt%.

[0041] (2) Filter paper pretreatment: KH550 (γ-aminopropyltriethoxysilane) was dissolved in ethanol solution to prepare a 2wt% solution, which was then sprayed evenly (spraying amount was 25mL / m). 2 On the hydrophilic layer surface of the filter paper, dry at 60°C for 5 minutes to form a surface ready for grafting.

[0042] (3) Filter paper modification treatment: Spray the modified liquid obtained in step (1) (spraying amount is 20mL / m) 2 Apply the modified filter paper to the hydrophilic layer surface of the filter paper after step (2), and then let it stand at room temperature for 30 minutes to allow it to spread fully; put it in a 60℃ oven to dry for 10 minutes to obtain the modified filter paper.

[0043] Example 3 A method for modifying filter paper, the specific steps of which are as follows: (1) Preparation of modified solution: Take 39g of polyvinyl alcohol (PVA) and add it to 200g of deionized water. Stir at 90℃ for 10 minutes until completely dissolved. Add 1g of urea and stir until completely dissolved. Mix it evenly and dilute with water to a total volume of 8000g to obtain a modified solution with a concentration of 0.5wt%.

[0044] (2) Filter paper pretreatment: KH550 (γ-aminopropyltriethoxysilane) was dissolved in ethanol solution to prepare a 2wt% solution, which was then sprayed evenly (spraying amount was 35mL / m). 2 On the hydrophilic layer surface of the filter paper, dry at 60°C for 5 minutes to form a surface ready for grafting.

[0045] (3) Filter paper modification treatment: Spray the modified liquid obtained in step (1) (spraying amount is 60mL / m) 2 Apply the modified filter paper to the hydrophilic layer surface of the filter paper after step (2), and then let it stand at room temperature for 30 minutes to allow it to spread fully; put it in a 60℃ oven to dry for 10 minutes to obtain the modified filter paper.

[0046] Example 4 A method for modifying filter paper, the specific steps of which are as follows: (1) Preparation of modified solution: Take 44g of polyvinylpyrrolidone (PVP) and add it to 200g of deionized water. Stir at 25℃ for 10 minutes until completely dissolved. Add 6g of LiBr and stir until completely dissolved. Mix it evenly and dilute with water to a total volume of 2000g to obtain a modified solution with a concentration of 2.5wt%.

[0047] (2) Filter paper pretreatment: Dissolve KH550 (γ-aminopropyltriethoxysilane) in ethanol solution to prepare a 2wt% solution, and spray it evenly (spraying amount is 40mL / m). 2 On the hydrophilic layer surface of the filter paper, dry at 60°C for 5 minutes to form a surface ready for grafting.

[0048] (3) Filter paper modification treatment: Spray the modified liquid obtained in step (1) (spraying amount is 20mL / m) 2 Apply the modified filter paper to the hydrophilic layer surface of the filter paper after step (2), and then let it stand at room temperature for 30 minutes to allow it to spread fully; put it in a 60℃ oven to dry for 10 minutes to obtain the modified filter paper.

[0049] Example 5 A method for modifying filter paper, the specific steps of which are as follows: (1) Preparation of modified solution: Take 42g of polyethyleneimine (PEI) and add it to 200g of deionized water. Stir at 25℃ for 10 minutes until completely dissolved. Add 8g of LiCl and stir until completely dissolved. Mix it evenly and dilute with water to a total volume of 2500g to obtain a modified solution with a concentration of 2wt%.

[0050] (2) Filter paper pretreatment: Dissolve KH550 (γ-aminopropyltriethoxysilane) in ethanol solution to prepare a 2wt% solution, and spray it evenly (spraying amount is 40mL / m). 2 On the hydrophilic layer surface of the filter paper, dry at 60°C for 5 minutes to form a surface ready for grafting.

[0051] (3) Filter paper modification treatment: Spray the modified liquid obtained in step (1) (spraying amount is 15mL / m) 2 Apply the modified filter paper to the hydrophilic layer surface of the filter paper after step (2), and then let it stand at room temperature for 30 minutes to allow it to spread fully; put it in a 60℃ oven to dry for 10 minutes to obtain the modified filter paper.

[0052] Comparative Example 1 The difference between this comparative example and Example 1 is that LiBr is not added. The specific preparation method is as follows: (1) Preparation of modified solution: Take 50g of polyethylene glycol diglycidyl ether (PEGDGE) and add it to 200g of deionized water. Stir at 25℃ for 10 minutes until completely dissolved. Dilute with water to a total volume of 2500g to obtain a modified solution with a concentration of 2wt%.

[0053] (2) Filter paper pretreatment: Dissolve KH550 (γ-aminopropyltriethoxysilane) in ethanol solution to prepare a 2wt% solution, and spray it evenly (spraying amount is 30mL / m). 2 On the hydrophilic layer surface of the filter paper, dry at 60°C for 5 minutes to form a surface ready for grafting.

[0054] (3) Filter paper modification treatment: Spray the modified liquid obtained in step (1) (spraying amount is 15mL / m) 2 Apply the modified filter paper to the hydrophilic layer surface of the filter paper after step (2), and then let it stand at room temperature for 30 minutes to allow it to spread fully; put it in a 60℃ oven to dry for 10 minutes to obtain the modified filter paper.

[0055] Comparative Example 2 The difference between this comparative example and Example 1 is that PEGDGE is not added. The specific preparation method is as follows: (1) Preparation of modified solution: Take 5g LiBr and add it to 200g deionized water. Stir at 25℃ until completely dissolved. Dilute with water to a total volume of 250g to obtain a modified solution with a concentration of 2wt%.

[0056] (2) Filter paper pretreatment: Dissolve KH550 (γ-aminopropyltriethoxysilane) in ethanol solution to prepare a 2wt% solution, and spray it evenly (spraying amount is 30mL / m). 2 On the hydrophilic layer surface of the filter paper, dry at 60°C for 5 minutes to form a surface ready for grafting.

[0057] (3) Filter paper modification treatment: Spray the modified liquid obtained in step (1) (spraying amount is 15mL / m) 2 Apply the modified filter paper to the hydrophilic layer surface of the filter paper after step (2), and then let it stand at room temperature for 30 minutes to allow it to spread fully; place it in a 60℃ oven and dry for 10 minutes to obtain the modified filter paper.

[0058] Comparative Example 3 The difference between this comparative example and Example 1 is that no pretreatment is performed on the filter paper. The specific preparation method is as follows: (1) Preparation of modified solution: Take 45g of polyethylene glycol diglycidyl ether (PEGDGE) and add it to 200g of deionized water. Stir at 25℃ for 10 minutes until completely dissolved. Add 5g of LiBr and stir until completely dissolved. Mix it evenly and dilute with water to a total volume of 2500g to obtain a modified solution with a concentration of 2wt%.

[0059] (2) Filter paper modification treatment: Spray the modified liquid obtained in step (1) (spraying amount is 15mL / m) 2 Apply the modified filter paper to the hydrophilic layer of the filter paper, then let it stand at room temperature for 30 minutes to allow it to spread fully; place it in a 60℃ oven and dry for 10 minutes to obtain the modified filter paper.

[0060] Comparative Example 4 The difference between this comparative example and Example 1 is that the amount of modified liquid used in step (3) is reduced. The specific preparation method is as follows: (1) Preparation of modified solution: Take 45g of polyethylene glycol diglycidyl ether (PEGDGE) and add it to 200g of deionized water. Stir at 25℃ for 10 minutes until completely dissolved. Add 5g of LiBr and stir until completely dissolved. Mix it evenly and dilute with water to a total volume of 2500g to obtain a modified solution with a concentration of 2wt%.

[0061] (2) Filter paper pretreatment: Dissolve KH550 (γ-aminopropyltriethoxysilane) in ethanol solution to prepare a 2wt% solution, and spray it evenly (spraying amount is 30mL / m). 2 On the hydrophilic layer surface of the filter paper, dry at 60°C for 5 minutes to form a surface ready for grafting.

[0062] (3) Filter paper modification treatment: Spray the modified liquid obtained in step (1) (spraying amount is 8mL / m) 2Apply the modified filter paper to the hydrophilic layer surface of the filter paper after step (2), and then let it stand at room temperature for 30 minutes to allow it to spread fully; put it in a 60℃ oven to dry for 10 minutes to obtain the modified filter paper.

[0063] Comparative Example 5 Filter paper in an unmodified commercial oil filter.

[0064] Performance testing The modified filter paper obtained in each embodiment and comparative example was tested for its performance in removing bound water from biodiesel. The test method is as follows: Biodiesel feedstock conforming to ASTM D6751 standard was taken and filtered through a commercial filter. The filtered biodiesel feedstock was collected (most free water and emulsion water were removed, with bound water being the main component). The initial bound water content in the diesel was determined by Karl Fischer coulometric titration (refer to ASTM D6304 or GB / T 11133). Under dry conditions, the filtered biodiesel feedstock was passed through a simulated filtration device equipped with modified filter paper at a constant flow rate of 20 mL / min. The biodiesel after the second filtration was collected, and its bound water content was measured again. The bound water removal rate was calculated as: bound water removal rate = (initial bound water content - bound water content after filtration) / initial bound water content × 100%. The test results are shown in Table 1 below.

[0065] Table 1

[0066] Test results show that the modified filter paper provided in this embodiment of the invention exhibits a significant effect in removing bound water from biodiesel. The differences in bound water removal rates among different embodiments indicate that the bound water removal effect of the modified filter paper is related to the types of primary and secondary modifiers used and the differences in their synergistic effects.

[0067] The bound water removal rate in Comparative Example 1 was significantly lower than that in Example 1, indicating that the addition of LiBr effectively enhances the hydrogen bonding ability between the main modifier and water molecules, improving the efficiency of competitively grabbing bound water. Comparative Example 2, using only LiBr without PEGDGE, had a bound water removal rate far lower than that in Example 1, demonstrating that simply free-distributed lithium salts cannot achieve stable and efficient bound water removal. The water-soluble polymer PEGDGE, rich in hydrogen bonding sites, is key to constructing efficient hydrogen bond competing sites: PEGDGE firmly binds to the original filter paper through KH550, laying a solid foundation for the stable pinning of lithium salts and their competitive role. Comparative Example 3, without pretreatment, lacked sufficient active sites on the filter paper surface to bind with the modifier, resulting in a reduced amount of modifier grafted onto the filter paper.

[0068] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A method for modifying filter paper for high-efficiency water removal, characterized in that, Includes the following steps: S1. Mix the main modifier, auxiliary modifier and water evenly to obtain the modified solution; The primary modifier is a water-soluble polymer rich in hydrogen bond sites; the secondary modifier is a small molecule hydrogen bond disruptor. S2. The surface of the hydrophilic layer of the filter paper substrate is modified and pretreated using a silane coupling agent; S3. The modified liquid is applied to the hydrophilic layer surface of the pretreated filter paper substrate, left to stand until the modified liquid is fully spread, and then dried to obtain the modified filter paper.

2. The method for modifying a high-efficiency water-removing modified filter paper according to claim 1, characterized in that, The main modifier includes at least one of polyethylene glycol diglycidyl ether, polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, polyacrylamide, polysaccharide, and polyethyleneimine.

3. The method for modifying a high-efficiency water-removing modified filter paper according to claim 1, characterized in that, The auxiliary modifier includes at least one of lithium bromide, lithium chloride, urea, and guanidine hydrochloride.

4. The method for modifying a high-efficiency water-removing modified filter paper according to claim 1, characterized in that, The mass ratio of the primary modifier to the secondary modifier is (5~40):

1.

5. The method for modifying a high-efficiency water-removing modified filter paper according to claim 1, characterized in that, The total concentration of the primary modifier and the secondary modifier in the modified liquid is 0.1wt%~10wt%.

6. The method for modifying a high-efficiency water-removing modified filter paper according to claim 1, characterized in that, The modification pretreatment specifically includes the following steps: spraying a silane coupling agent solution onto the hydrophilic layer surface of the filter paper substrate and drying it.

7. The method for modifying a high-efficiency water-removing modified filter paper according to claim 6, characterized in that, The concentration of the silane coupling agent solution is 1wt%~5wt%; And / or, the spraying amount of the silane coupling agent solution is 15~60 mL / m 2 ; And / or, the drying temperature is 50~100℃, and the drying time is 5~30 minutes.

8. The method for modifying a high-efficiency water-removing modified filter paper according to claim 1, characterized in that, In step S3, the coating amount of the modified liquid is 10~100mL / m 2 ; And / or, the settling time is 20 to 60 minutes; And / or, the drying temperature is 50~100℃, and the drying time is 5~30 minutes.

9. A modified filter paper for high-efficiency water removal, characterized in that, It is prepared by any of the modification methods described in claims 1 to 8.

10. The application of the modified filter paper with high efficiency water removal as described in claim 9 in the oil-water separation of biodiesel.

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