Porous alkylated polyurethane oil absorption material as well as preparation method and application thereof

Abstract

The invention discloses a porous alkylated polyurethane oil absorption material as well as a preparation method and application thereof, and belongs to the technical field of oil absorption materials. The preparation method comprises the following steps: taking isocyanate and dihydric alcohol with an R ratio of 1.4-1.8, and carrying out condensation polymerization reaction on the isocyanate and the dihydric alcohol to generate a first polyurethane prepolymer; reacting the first polyurethane prepolymer with a chain extender to generate a polyurethane prepolymer; reacting the polyurethane prepolymer with medium-chain fatty alcohol in a mass ratio of (8-12): 1 to generate an alkylated polyurethane precursor; and adding a set amount of calcite particles into the alkylated polyurethane precursor, uniformly mixing, adding a cross-linking agent for reaction, and soaking with an HCl solution to remove the calcite particles, thereby obtaining the porous alkylated polyurethane oil absorption material. According to the invention, the defect that a molecular chain of traditional polyurethane foam contains a large number of polar groups can be overcome, so that the hydrophobicity and lipophilicity are improved; meanwhile, the aperture structure is regulated and controlled by combining a hard template method, so that the cost is reduced and the technological process is simplified.

Description

Technical Field

[0001] The invention belongs to the technical field of oil-absorbing materials, and in particular relates to a porous alkylated polyurethane oil-absorbing material, a preparation method thereof and an application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Oil and organic solvent spills can cause serious oil pollution in water bodies. Treatment methods include chemical, in-situ combustion, biological, and physical methods. Among physical methods, the use of adsorption materials primarily utilizes van der Waals forces to adsorb oil and organic solvent molecules, achieving high selectivity.

[0004] Common oil-absorbing materials currently available include inorganic materials (such as vermiculite, zeolite, activated carbon, bentonite, expanded graphite, and aerogel), natural organic materials (such as hay, corncobs, and cotton), and synthetic organic materials. Inorganic materials have high density and low buoyancy, making subsequent recycling difficult. Natural organic materials, however, exhibit poor hydrophobicity and weak buoyancy, making them unsuitable for cleaning up large oil spills. There are many types of organic synthetic oil-absorbing materials, with polyethylene and polyurethane being common. Their pore size and spatial distribution can be precisely controlled during preparation, and their recyclability generally outperforms electrospun fibers and some foam materials. However, traditional porous polyurethane materials are rich in polar groups and highly hydrophilic, requiring hydrophobic modification for efficient oil absorption. However, porous polyurethane materials are often prepared by foaming methods, resulting in a high degree of internal crosslinking, making the modification of the finished product complex. Therefore, the facile preparation of hydrophobic and oleophilic porous polyurethane materials remains a pressing technical challenge for those skilled in the art. Summary of the Invention

[0005] To address the shortcomings of the existing technology, the present invention provides a porous alkylated polyurethane oil-absorbing material, its preparation method, and its application. First, a linear first polyurethane prepolymer is produced by condensation polymerization of an isocyanate and a diol. This is then reacted with a chain extender to produce an NCO-terminated polyurethane prepolymer. The prepolymer is then reacted with a medium-chain fatty alcohol to produce an alkylated polyurethane precursor. A hard template method is then used to produce a product with a predetermined pore size.

[0006] In order to achieve the above object, the technical solution of the present invention is: In a first aspect, a method for preparing a porous alkylated polyurethane oil-absorbing material comprises the steps of: S1, taking an isocyanate and a diol with an R ratio of 1.4 to 1.8, and subjecting the isocyanate and the diol to a condensation polymerization reaction to generate a first polyurethane prepolymer; S2, reacting the first polyurethane prepolymer with a chain extender to generate a polyurethane prepolymer; S3, reacting a polyurethane prepolymer with a medium-chain fatty alcohol in a mass ratio of (8-12):1 to generate an alkylated polyurethane precursor; S4. Adding a set amount of calcite particles to the alkylated polyurethane precursor, mixing well, adding a crosslinking agent for reaction, and then soaking in HCl solution to remove the calcite particles to obtain a porous alkylated polyurethane oil-absorbing material.

[0007] In a second aspect, the porous alkylated polyurethane oil-absorbing material is prepared by the above-mentioned method for preparing the porous alkylated polyurethane oil-absorbing material.

[0008] In a third aspect, the porous alkylated polyurethane oil-absorbing material is used to treat oil-contaminated water bodies.

[0009] The beneficial effects of the present invention are: 1. This invention utilizes a prepolymer method to prepare an isocyanate (-NCO)-terminated polyurethane prepolymer. Alkylation modification is achieved in the early stages of preparation through reaction with the hydroxyl (-OH) groups of medium-chain fatty alcohols. This overcomes the drawback of conventional polyurethane foams, which often contain numerous polar groups (such as carbamate and ether bonds) in their molecular chains, thereby enhancing their hydrophobicity and lipophilicity. Furthermore, a hard template method is employed to control the pore size structure, reducing costs and streamlining the process.

[0010] 2. The porous alkylated polyurethane oil-absorbing material prepared by the present invention has a water contact angle of approximately 126° and exhibits excellent adsorption performance for oils or organic solvents such as gasoline, diesel, soybean oil, motor oil, kerosene, petroleum ether, cyclohexane, chloroform, and toluene. It also maintains high reusability after multiple adsorption-centrifugal desorption cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0012] Figure 1 1 is the infrared spectrum of PUP, APUP, CAPU and PAPU in Example 1 of the present invention.

[0013] Figure 2 These are scanning electron microscope images of Example 1 of the present invention; (a) is CAPU and (b) is PAPU.

[0014] Figure 3 These are water contact angle images in Example 1 of the present invention; wherein (a) is CAPU and (b) is PAPU.

[0015] Figure 4 This is a statistical chart of the adsorption capacity of the PAPU oil-absorbing material prepared in Example 1 of the present invention for different oils and organic solvents.

[0016] Figure 5 Figures show the effect of different adsorption times on the adsorption capacity of oil and organic solvents of the PAPU oil-absorbing material prepared in Example 1 of the present invention; (a) is 30 min; (b) is 60 min; (c) is 150 min; and (d) is 300 min.

[0017] Figure 6 This is the adsorption kinetic model of the PAPU oil absorbing material prepared in Example 1 of the present invention.

[0018] Figure 7 This is the Langmuir adsorption isotherm of the PAPU oil absorbing material prepared in Example 1 of the present invention.

[0019] Figure 8 This is the Freundlich adsorption isotherm of the PAPU oil absorbing material prepared in Example 1 of the present invention.

[0020] Figure 9 Graph showing the effect of temperature on the thermodynamic properties of the PAPU oil absorbing material prepared in Example 1 of the present invention when adsorbing 50 mL of a diesel and water mixture with a relative concentration of 10 g / L.

[0021] Figure 10 This is a dynamic image of the PAPU prepared in Example 1 of the present invention contacting and adsorbing soybean oil on the water surface; Figure 11 This is a dynamic image of the PAPU prepared in Example 1 of the present invention contacting and adsorbing chloroform under the water surface; Figure 12 This is a diagram showing the reuse performance of the PAPU prepared in Example 1 of the present invention; wherein (a) is the adsorption capacity and (b) is the reuse efficiency.

[0022] Figure 13 This is the infrared characterization result of the chain extender PUC in Preparation Example 1 of the present invention.

[0023] Figure 14 Schematic diagram of the reaction flow of steps S1 to S2 in Example 1 of the present invention.

[0024] Figure 15 Schematic diagram of the reaction flow of steps S3-S4 in Example 1 of the present invention. DETAILED DESCRIPTION

[0025] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0026] In one or more embodiments provided by the present invention, a method for preparing a porous alkylated polyurethane oil-absorbing material is provided, comprising the steps of: S1, taking an isocyanate and a diol with an R ratio of 1.4 to 1.8, and subjecting the isocyanate and the diol to a condensation polymerization reaction to generate a first polyurethane prepolymer; S2, reacting the first polyurethane prepolymer with a chain extender to generate a polyurethane prepolymer; S3, reacting a polyurethane prepolymer with a medium-chain fatty alcohol in a mass ratio of (8-12):1 to generate an alkylated polyurethane precursor; S4. Adding a set amount of calcite particles to the alkylated polyurethane precursor, mixing well, adding a crosslinking agent for reaction, and then soaking in HCl solution to remove the calcite particles to obtain a porous alkylated polyurethane oil-absorbing material.

[0027] In the above method, isocyanate and diol are first subjected to a condensation polymerization reaction to form a linear first polyurethane prepolymer (PUP-1). Then, the first polyurethane prepolymer is reacted with a chain extender (PUC) to form an NCO-terminated polyurethane prepolymer (PUP). Then, PUP is reacted with a long-chain fatty alcohol to form an alkylated polyurethane precursor (APUP). Subsequently, APUP, calcite, and a crosslinker are thoroughly mixed and heated to form a cross-linked-alkylated polyurethane containing calcite particles (CAPU / calcite). After that, the mixture is immersed in a dilute HCl solution for a set time to remove the calcite and leave pores. Finally, it is dried to a constant weight to obtain a porous alkylated polyurethane (PAPU).

[0028] Optionally, in S1, the R ratio (referring to the molar ratio of isocyanate groups "-NCO" to hydroxyl groups "-OH") will affect whether the reaction can be fully completed. An R ratio that is too large or too small will affect the degree of alkylation reaction, thereby affecting the oil absorption performance of the reaction product. The R ratio is preferably 1.4.

[0029] Optionally, in S1, the isocyanate is diphenylmethane diisocyanate (MDI), and the diol includes one or more of diethylene glycol, triethylene glycol and tetraethylene glycol; the molecular weight of diethylene glycol is 106.12 g / mol, the molecular weight of triethylene glycol is 150.18 g / mol, and the molecular weight of tetraethylene glycol is 194.22 g / mol, preferably 106.12 g / mol of diethylene glycol; the molecular weight of the diol has an important influence on the hydrophobic and lipophilic properties of the polyurethane, and a diol with too high a molecular weight will increase the hydrophilicity of the material, which is not conducive to the preparation of oil-absorbing materials.

[0030] Optionally, in S3, the medium-chain fatty alcohol includes one or more of n-hexanol, n-heptanol, n-octanol, n-decanol and n-dodecyl alcohol, preferably n-decanol; the mass ratio of the medium-chain fatty alcohol to the polyurethane prepolymer is 1: (8~12).

[0031] Optionally, in S2, the chain extender is selected from the chain extender PUC or diethanolamine, and the structural formula of the chain extender PUC is: .

[0032] Optionally, in S2, the amount of the chain extender added is 5 to 35% by weight of the isocyanate added to the first polyurethane prepolymer, preferably 15 wt% to 25 wt%, and more preferably 20 wt%.

[0033] Optionally, in S4, the mass ratio of the crosslinker to the alkylated polyurethane precursor is 1: (28~32).

[0034] Optionally, in S4, the particle size of the calcite particles includes one or more of 0.10-0.18 mm, 0.18-0.40 mm, and 0.40-0.85 mm, preferably 0.18-0.40 mm.

[0035] Optionally, in S4, the calcite particles account for 40-70 wt %, preferably 60 wt %, of the alkylated polyurethane precursor.

[0036] Optionally, in S1 to S4, the reaction is carried out in an inert atmosphere.

[0037] In one or more embodiments provided by the present invention, a porous alkylated polyurethane oil-absorbing material prepared by the above-mentioned method for preparing the porous alkylated polyurethane oil-absorbing material is provided.

[0038] In one or more embodiments provided by the present invention, there is provided the use of the above-mentioned porous alkylated polyurethane oil-absorbing material in treating oil-contaminated water bodies.

[0039] Optionally, the oil-contaminated water body includes a mixture of a water-insoluble organic solvent and water.

[0040] Preparation Example 1 A method for preparing a chain extender PUC (polyurethane chain extender), the reaction process is as follows: .

[0041] The PUC chain extender was prepared in an oil bath system by first adding 0.10 g of MDI solid and then 1.5 mL of xylene solvent. The mixture was dissolved by magnetic stirring for 20 min. A solution obtained by mixing 0.5 mL of DMF and 0.0184 g of glycerol was then added. The reaction temperature was 50 °C and the reaction was continued for 2 h to obtain PUC with dihydroxy functional groups.

[0042] Infrared Characterization of Chain Extender PUC Figure 13 As shown, it can be seen from infrared that 3339 cm -1 is the stretching vibration absorption peak of OH bond, 2306 cm -1 The N=C=O stretching vibration absorption peak is the critical reaction between propylene glycol and isocyanate. The special functional groups of both are not completely consumed, which is beneficial to the subsequent chain extension and alkylation reaction; 2870 cm -1 The peak of the symmetrical stretching vibration of the C-H bond is 1841 cm -1 The peak enhancement at comes from the CO stretching and bending stretching vibration peak belonging to the C=O bond, which proves that PUC was successfully prepared.

[0043] Example 1 A porous alkylated polyurethane (PAPU) oil-absorbing material, the preparation method of which includes the following process.

[0044] S0. The pretreatment process includes organic solvent pretreatment, reaction monomer pretreatment and calcite pretreatment, which provides an anhydrous environment for the preparation of polyurethane. If the water content of the monomer and solvent is too high, it will affect the reaction and generate hydrophilic by-products.

[0045] The organic solvent pretreatment method includes: activating the 4A molecular sieve in a muffle furnace to ensure that the molecular sieve reaches the optimal activity state; selecting N,N-dimethylformamide (DMF) and xylene as the organic solvents required for the experiment, adding 4A molecular sieves into brown reagent bottles containing the above-mentioned single-type organic solvents at a ratio of 0.1 g / mL, sealing and standing for 24 hours. During the standing period, the 4A molecular sieve fully exerts its adsorption effect to remove moisture in the organic solution, so that the organic solution meets the strict requirement of being anhydrous during the preparation process.

[0046] The reaction monomer pretreatment method includes: adding the activated 4A molecular sieve into a brown reagent bottle containing the reaction monomer according to a ratio of 10:1 between the mass of the reaction monomer and the 4A molecular sieve, stirring thoroughly to allow the molecular sieve to contact the reaction monomer, sealing and standing for 24 hours. During the standing period, the 4A molecular sieve can effectively absorb the free water in the reaction monomer, meeting the strict requirement of anhydrous in the preparation process.

[0047] The calcite pretreatment method includes: grinding the calcite raw material and sieving it to obtain calcite powder with a particle size of 0.18-0.40 mm, which is then ultrasonically cleaned in deionized water for 15 minutes to remove mixed dust and water-soluble impurities; after cleaning, the calcite powder is placed in a vacuum drying oven at 150°C for 10 hours to fully remove moisture from the inside and surface of the calcite; after drying, when the temperature in the vacuum drying oven drops to room temperature, the calcite powder is immediately removed and sealed in a drying oven to prevent it from reabsorbing moisture in the air; so that the calcite meets the strict requirement of being water-free during the preparation process. Calcite is a key raw material for the preparation of porous alkylated polyurethane materials, and its degree of dryness can affect the final performance of the material.

[0048] S1. Pre-mix 0.2827 g of diethylene glycol and 5 mL of xylene, then stir continuously at high speed for 1 h to obtain a diethylene glycol solution. Place a three-necked flask in a constant temperature oil bath (an oil bath is used to prevent water volatilization in the water bath from affecting the experimental system), purge with nitrogen for 20 min, add 1.00 g of MDI solid first, then add 5 mL of xylene solvent, set the reaction temperature to 50°C, and magnetically stir for 20 min to dissolve. Then, add diethylene glycol to the three-necked flask and continue the reaction for 6 h to obtain a solution containing the first polyurethane prepolymer (PUP-1). At this time, the R ratio is 1.5.

[0049] S2. Place another three-necked flask in a constant temperature oil bath and purge with nitrogen for 20 min. Set the oil bath temperature to 50°C and add the solution containing PUP-1 obtained in S1. Then add 0.2 g of polyurethane chain extender (PUC) and continue the reaction for 4 h to obtain a solution containing polyurethane prepolymer (PUP).

[0050] The reaction process of S1~S2 above is as follows Figure 14S3. Place another three-necked flask in a constant temperature oil bath and purge with nitrogen for 20 minutes. Set the oil bath temperature to 50°C and add the solution containing PUP obtained in S2. Then, add 0.9 mmol of n-decanol and 0.002 g of 4-dimethylaminopyridine (DMAP, catalyst) and continue the reaction for 8 hours to obtain a solution containing alkylated polyurethane prepolymer (APUP). After cooling naturally to room temperature, transfer the solution containing APUP to a centrifuge tube and centrifuge at 10,000 rpm for 10 minutes to separate APUP from the solution.

[0051] S4. Take 2 mL of DMF and 0.09 mmol of polyethyleneimine (PEI, cross-linker) in advance and mix them to obtain a cross-linker solution; add 60 wt% of calcite powder to the APUP obtained in S3, stir thoroughly and mix well, then add the cross-linker solution, and continue the reaction at 40°C for 4 hours to obtain a cross-linked-alkylated polyurethane (CAPU / calcite) containing calcite. After naturally cooling to room temperature, transfer the CAPU / calcite to a conical flask connected to a condenser and filled with 3 wt% dilute hydrochloric acid. Continue soaking and reacting at room temperature for 48 hours, remove the calcite powder, and then dry to obtain a porous alkylated polyurethane (PAPU) oil-absorbing material.

[0052] The reaction process of the above steps S3~S4 is as follows Figure 15 shown.

[0053] According to the steps of S4, a crosslinker solution was added to the APUP obtained in S3 and the reaction was continued at 40°C for 4 hours to obtain a calcite-free cross-linked-alkylated polyurethane (CAPU) for subsequent testing.

[0054] Composition and structure analysis The infrared spectra of PUP obtained in S2, APUP obtained in S3, PAPU obtained in S4 and CAPU without calcite are shown in FIG. Figure 1 As shown, it can be seen that: (1) 1716 cm -1 It is the stretching vibration absorption peak of carbonyl C=O, 2203cm -1 It is the stretching vibration absorption peak of N=C=O, but there is no OH characteristic absorption peak, which indicates that the prepolymerization reaction is complete and the hydroxyl groups of the polyol are consumed, confirming that the N=C=O terminated polyurethane prepolymer PUP has been successfully synthesized; (2) APUP is the product obtained by the reaction of PUP with fatty alcohol, 2915 cm -1 The symmetrical stretching vibration peak of the C-H bond at 3000-3500 cm-1 is significantly enhanced, and the stretching vibration absorption peak of N=C=O is significantly weakened, indicating that PUP has been alkylated and exhibits a stable characteristic peak enhanced by the lipophilic group; (3) CAPU compared with APUP, at 3000-3500 cm-1-1 The NH bond absorption peak that appeared was significantly enhanced, proving that APUP and PEI were successfully cross-linked and CAPU was successfully synthesized; (4) PAPU was obtained by adding a calcite template to CAPU and then soaking it in dilute hydrochloric acid. Compared with CAPU, there was no obvious change in the chemical structure. The characteristic peak of the N=C=O group completely disappeared, proving that the reaction was more thorough and the material structure was more stable, reflecting the superiority of using the template method to prepare porous alkylated materials and proving the successful synthesis of PAPU.

[0055] The scanning electron microscope images of CAPU and PAPU in this embodiment are as follows: Figure 2 As shown, it can be seen that: CAPU polymer chains are cross-linked and entangled, and the surface is relatively rough, so oil molecules can have a higher oil absorption rate in CAPU; PAPU has a large number of pore structures while retaining the rough and wrinkled surface characteristics of CAPU, with an increased specific surface area. The rate at which oil molecules migrate into the material is faster, and the porous structure can improve the oil absorption performance of PAPU.

[0056] The water contact angle images of CAPU and PAPU in this embodiment are as follows Figure 3 As shown, it can be seen that the water contact angle of CAPU is 117.97°, and the contact angle of PAPU is 126.13°. Due to the addition of calcite particles during the cross-linking process, PAPU has a lower cross-linking density than CAPU and a higher degree of alkylation. In addition, the high specific surface area provides a large number of oil molecule adsorption sites, and its affinity with oils is higher than that with water, forming a hydrophobic surface, making it difficult for water molecules to adhere to the surface of the material.

[0057] The results of the determination of the C, H, and N element contents in PUP, APUP, CAPU, and PAPU in this example are shown in Table 1: the C and H contents in APUP are significantly higher than those in PUP, demonstrating that the polyurethane prepolymer successfully reacts with the long-chain fatty alcohol, adding long-chain alkyl groups and achieving alkylation; the N and H contents in CAPU are higher than those in APUP, which is caused by the use of a cross-linking agent with a higher N content; the N element content in PAPU is slightly higher than that in CAPU, which means that during the preparation process of PAPU, when calcite is removed, its reaction with dilute hydrochloric acid does not affect the material structure and is conducive to further improving the degree of alkylation of the material.

[0058] Table 1

[0059] Adsorption or reuse performance test The porous alkylated polyurethane (PAPU) oil-absorbing material prepared in this example was subjected to an adsorption test on 9 different oil products and organic solvents to be tested (motor oil, soybean oil, diesel, kerosene, gasoline, chloroform, toluene, cyclohexane or petroleum ether): a dry mass of PAPU oil-absorbing material m0 (about 0.1 g) was weighed and placed in a non-woven bag, which was then completely immersed in a chromatography bar containing the oil product or organic solvent to be tested, and adsorbed at room temperature for 300 minutes; the string on the bag was then pulled to completely suspend the oil product or organic solvent layer on the chromatography bar, and the material was allowed to stand for 2 minutes until no more liquid dripped, after which the oil-absorbing material was quickly removed, weighed immediately and the mass m1 was recorded. The adsorption process for soybean oil dyed red on the water surface is as follows: Figure 10 As shown, Figure 10 To take snapshots at different time points, PAPU can completely adsorb oil with a density lower than that of water within 10 seconds; the process of adsorbing chloroform dyed red under the water surface is as follows: Figure 11 As shown in the figure, which shows snapshots taken at different time points, PAPU can completely adsorb oil with a density greater than water within 10 s.

[0060] The adsorption capacity of PAPU oil absorbing material for various oils and organic solvents is calculated according to formula (1): , (1); Where Q (g / g) is the adsorption capacity of the oil-absorbing material per unit mass for different oils and organic solvents; m0 (g) represents the mass of the oil-absorbing material before adsorption; and m1 (g) represents the mass of the oil-absorbing material after adsorption.

[0061] The adsorption capacity of the PAPU oil absorbing material prepared in Example 1 for various oils and organic solvents is as follows: Figure 4 As shown in the figure, it can be seen that the average adsorption capacity of the oil-absorbing material prepared by the present invention for toluene is 11.52 g / g, the average adsorption capacity for chloroform is 22.04 g / g, the average adsorption capacity for cyclohexane is 10.16 g / g, and the average adsorption capacity for petroleum ether is relatively low, which is 5.15 g / g; the oil-absorbing material also has good adsorption capacity for various oil products, with an average adsorption capacity for engine oil of 20.74 g / g, a maximum average adsorption capacity for soybean oil of 12.81 g / g, a maximum average adsorption capacity for diesel of 12.26 g / g, a maximum average adsorption capacity for gasoline of 10.44 g / g, and a maximum average adsorption capacity for kerosene of 10.66 g / g.

[0062] Compared with the adsorption capacity of several other traditional oil-absorbing materials, it was found that the oil absorption performance of PAPU oil-absorbing material is relatively excellent. The specific data are shown in Table 2.

[0063] Table 2

[0064] The adsorption kinetics analysis method includes: weighing a certain mass m0 (about 0.1 g) of PAPU oil-absorbing material and placing it in a non-woven bag, and then completely immersing it in a chromatography bar containing diesel, chloroform, and soybean oil respectively. After different adsorption times, the oil-absorbing material is drained, taken out, and quickly weighed and m1 is recorded. The adsorption capacity of the oil-absorbing material at different times is calculated according to formula (1), and then the relationship curve between adsorption capacity and contact time is plotted. The experimental data are fitted using pseudo-first-order and pseudo-second-order nonlinear kinetic models. The fitting parameters obtained according to the adsorption capacity at different times are shown in Table 3. Among them, Figure 5 (a) is the adsorption time of 30 min; (b) is the adsorption time of 60 min; (c) is the adsorption time of 150 min; (d) is the adsorption time of 300 min. The adsorption kinetic model obtained is as follows: Figure 6 As shown in the figure, the adsorption capacity of the oil-absorbing material for various oils and organic solvents shows a trend of increasing first and then stabilizing with prolonged adsorption time. Within the initial 30 minutes of adsorption, the adsorption capacity increases rapidly with increasing contact time, with a significant adsorption rate and the maximum slope of the curve. Over time, the increase in adsorption capacity decreases, the adsorption rate slows, and the slope of the curve decreases accordingly. After 120 minutes of adsorption, the adsorption capacity remains essentially constant, the adsorption process approaches equilibrium, and the curve flattens. Furthermore, the pseudo-second-order kinetic model better describes the adsorption process of the oil-absorbing material than the pseudo-first-order model. The rate constant k² of the pseudo-second-order kinetic equation shows that the adsorption rate of the oil-absorbing material is the fastest for diesel, followed by kerosene, and the slowest for chloroform. Notably, the order of adsorption rates is exactly opposite to the order of polarity of the three solvents, indicating a negative correlation between adsorption rate and solvent polarity.

[0065] Table 3

[0066] The isothermal adsorption model analysis method includes: preparing 50 mL of oil-water mixture with different relative concentrations and placing it in a glass bottle (volume 50 mL); then weighing a certain mass m0 (about 0.1 g) of PAPU oil-absorbing material and completely immersing it in the glass bottle; then placing the sealed glass bottle in a digital water bath constant temperature oscillator, setting the water bath temperature to 30 °C and the oscillation rate to 100 rpm; adsorbing under constant temperature oscillation for 300 min, quickly taking it out and weighing it and recording m1, and then calculating its adsorption capacity in oil-water mixtures with different relative concentrations and the equilibrium relative concentration of diesel, and using the Langmuir and Freundlich isotherm models to fit the adsorption experimental data. The obtained fitting parameters are shown in Table 4. Among them, according to the different diesel mass and water volume, the relative concentrations are selected as 2, 4, 6, 8, 10, 12, 14 and 16 g / L. The obtained Langmuir adsorption isotherm is shown in Figure 4. Figure 7 As shown in the Freundlich adsorption isotherm, Figure 8 shown.

[0067] Table 4

[0068] The adsorption thermodynamic analysis method includes the following steps: adding 50 mL of a diesel / water mixture with a relative concentration of 10 g / L to a glass bottle, then weighing a certain mass m0 (approximately 0.1 g) of PAPU oil-absorbing material and placing it in a sealed glass bottle. The material was placed in a digital water bath thermostat at 298.15, 308.15, 318.15, and 328.15 K, with the oscillation rate set at 100 rpm, and subjected to constant temperature oscillation adsorption for 300 min. The material was quickly removed, weighed, and the mass m1 recorded. The adsorption capacity of the material and the relative concentration of the remaining diesel / water mixture in the glass bottle were then calculated. Thermodynamic parameters such as Gibbs free energy ∆G0 (kJ / mol), enthalpy change ∆H0 (kJ / mol), and entropy change ∆S0 [J / (mol·K)] were used to evaluate the effect of temperature on the adsorption process. The obtained thermodynamic parameters are shown in Table 5. The thermodynamic performance influence diagram is shown in Figure 5. Figure 9 As shown, it shows that diesel adsorption is a spontaneous and exothermic process, high temperature is not conducive to adsorption, and there is physical adsorption in the adsorption process of diesel by the oil-absorbing material.

[0069] Table 5

[0070] The reusability test method includes: weighing a dry mass of PAPU oil-absorbing material m0 (about 0.1 g) and placing it in a non-woven bag; performing an adsorption operation: completely immersing it in a chromatography bar filled with diesel, and after adsorption for 300 minutes, taking the bag out of the oil layer, letting it stand until no oil drops, quickly taking out the material, weighing it, and recording the mass m1, and calculating the material adsorption capacity according to formula (1); then performing a centrifugation operation: transferring the adsorption equilibrium sample to a centrifuge tube, rotating at 10,000 rpm, centrifuging for 5 minutes, removing the adsorbed diesel, and weighing it again (recorded as m1). t , t represents the number of adsorption times); repeat the above adsorption-centrifugation operation 10 times, and calculate the reuse efficiency according to formula (2).

[0071] , (2); Repeated use performance test results such as Figure 12 As shown, from Figure 12 As can be seen from (a), after 10 cycles of adsorption-desorption, the adsorption capacity of the oil-absorbing material for diesel remains basically the same as the initial adsorption capacity, and the quality has no obvious change; Figure 12 The recycling efficiency shown in (b) is stably maintained at above 95%, proving that the oil-absorbing material has good adsorption capacity, reusability and good practical application prospects.

[0072] Example 2 A porous alkylated polyurethane (PAPU) oil-absorbing material, the preparation method of which differs from that of Example 1 in that: In S1, when preparing the diethylene glycol solution, the amount of diethylene glycol added was 0.2651 g; at this time, the R ratio was 1.4.

[0073] In S3, n-octanol was added instead of n-decanol, and the amount of n-octanol added was 1.5 mmol. In S4, during the preparation of the cross-linker solution, the amount of polyethyleneimine (PEI, cross-linker) added was 0.08 mmol to obtain a porous alkylated polyurethane (PAPU) oil-absorbing material, and at the same time, calcite-free CAPU was prepared according to the same addition ratio for subsequent testing.

[0074] During performance testing, due to the increased amount of diethylene glycol added, the R ratio decreased, and there were not enough isocyanate groups to participate in the subsequent alkylation and cross-linking reactions; the use of n-octanol as a medium-chain fatty alcohol reduced the chain length, which was not conducive to improving the hydrophobic and lipophilic properties of the material; and the amount of cross-linker added decreased, the polyurethane cross-linking reaction was insufficient, and the formed network structure was relatively loose, with a small adsorption capacity for oil products. Therefore, the technical effect was not as good as the preferred solution.

[0075] Example 3 A porous alkylated polyurethane (PAPU) oil-absorbing material, the preparation method of which is different from that of Example 1 in that: in S2, the added chain extender is 25 wt% of the mass of the isocyanate.

[0076] Other raw materials and preparation methods are the same as in Example 1.

[0077] During the performance test, the amount of chain extender added increased. Since the principle of adding chain extender is similar to that of adding cross-linking agent, both will increase the cross-linking density of the material. Excessive addition is not conducive to the swelling and adsorption of the material during the oil absorption process. Therefore, the technical effect is not as good as the preferred solution.

[0078] Example 4 A porous alkylated polyurethane (PAPU) oil-absorbing material, the preparation method of which is different from that of Example 1 in that: in S2, the added chain extender is diethanolamine, and the added amount is 35 wt% of the isocyanate.

[0079] Other raw materials and preparation methods are the same as in Example 1.

[0080] During the performance test, since the amount of chain extender added increased significantly, the cross-linking density of the material was too high, which was not conducive to improving the oil absorption performance of the material, and the technical effect was not as good as the preferred solution.

[0081] Example 5 A porous alkylated polyurethane (PAPU) oil-absorbing material is prepared by a method different from that of Example 1, in which the particle size of the calcite particles prepared in S0 is 0.10-0.18 mm, and the amount of calcite particles added in S4 accounts for 40 wt % of the alkylated polyurethane precursor.

[0082] Other raw materials and preparation methods are the same as in Example 1.

[0083] During the performance test, as the calcite particle size became smaller and the added amount became less, the density of the material increased, the porosity decreased, and the water contact angle decreased, which was not conducive to the hydrophobic and oleophilic properties of the material.

[0084] Example 6 A porous alkylated polyurethane (PAPU) oil-absorbing material, the preparation method of which differs from that of Example 1 in that the particle size of the calcite particles prepared in S0 is 0.40-0.85 mm, and the amount of calcite particles added in S4 accounts for 70 wt % of the alkylated polyurethane precursor.

[0085] Other raw materials and preparation methods are the same as in Example 1.

[0086] In the performance test, as the calcite particle size becomes larger and the added amount increases, the density of the material decreases and the porosity increases, but the water contact angle decreases greatly, indicating that the hydrophobic and lipophilic properties are destroyed. Therefore, the technical effect is not as good as the preferred solution.

[0087] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a porous alkylated polyurethane oil-absorbing material, characterized in that: Including steps: S1, taking an isocyanate and a diol with an R ratio of 1.4 to 1.8, and subjecting the isocyanate and the diol to a condensation polymerization reaction to generate a first polyurethane prepolymer; S2, reacting the first polyurethane prepolymer with a chain extender to generate a polyurethane prepolymer; S3, reacting a polyurethane prepolymer with a medium-chain fatty alcohol in a mass ratio of (8-12):1 to generate an alkylated polyurethane precursor; S4. Adding a set amount of calcite particles to the alkylated polyurethane precursor, mixing well, adding a crosslinking agent for reaction, and then soaking in HCl solution to remove the calcite particles to obtain a porous alkylated polyurethane oil-absorbing material.

2. The method for preparing a porous alkylated polyurethane oil-absorbing material according to claim 1, wherein: In S1, the isocyanate is diphenylmethane diisocyanate, and the diol includes one or more of diethylene glycol, triethylene glycol, and tetraethylene glycol.

3. The method for preparing a porous alkylated polyurethane oil-absorbing material according to claim 1, wherein: The medium-chain fatty alcohol includes one or more of n-hexanol, n-heptanol, n-octanol, n-decanol and n-dodecanol, preferably n-decanol.

4. The method for preparing a porous alkylated polyurethane oil-absorbing material according to claim 1, wherein: In S2, the chain extender is selected from the chain extender PUC or diethanolamine, and the chain extender PUC has the structural formula: ； Alternatively, the amount of the chain extender added is 5 to 35% by weight of the isocyanate, preferably 15 to 25 wt%, and more preferably 20 wt%.

5. The method for preparing a porous alkylated polyurethane oil-absorbing material according to claim 1, wherein: In S4, the mass ratio of the crosslinker to the alkylated polyurethane precursor is 1: (28~32).

6. The method for preparing a porous alkylated polyurethane oil-absorbing material according to claim 1, wherein: In S4, the particle size of the calcite particles includes one or more of 0.10-0.18 mm, 0.18-0.40 mm, and 0.40-0.85 mm, preferably 0.18-0.40 mm; Alternatively, in S4, the calcite particles account for 40 to 70 wt %, preferably 60 wt %, of the alkylated polyurethane precursor.

7. The method for preparing a porous alkylated polyurethane oil-absorbing material according to claim 1, wherein: In S1 to S4, the reaction is carried out in an inert atmosphere.

8. A porous alkylated polyurethane oil-absorbing material prepared by the method for preparing a porous alkylated polyurethane oil-absorbing material according to any one of claims 1 to 7.

9. Use of the porous alkylated polyurethane oil-absorbing material according to claim 8, characterized in that: The applications include: application in treating oil-contaminated water bodies.

10. The use according to claim 9, characterized in that The oil-contaminated water body includes a mixture of a water-insoluble organic solvent and water.

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