Waste oil-based emulsifier and preparation method thereof

Abstract

The present invention provides a waste grease-based emulsifier and a preparation method thereof. The method of the present invention is to use waste grease as the main raw material, graft and modify it by diamine, then graft 2,3-epoxypropyltrimethylammonium chloride hydrophilic groups, and characterize the molecular structure and physicochemical properties of the emulsifier by means of Fourier infrared spectroscopy, surface tension measurement, etc. The excellent emulsifying performance of the waste grease-based emulsifier synthesized by the present invention is due to the rich carbon chain of the waste grease, which has excellent lipophilicity. The quaternary ammonium salt group carried by 2,3-epoxypropyltrimethylammonium chloride gives the emulsifier excellent hydrophilicity. The emulsifier can disperse asphalt to form emulsified asphalt, wherein asphalt is used as a dispersed phase and water is used as a continuous phase, and the asphalt is dispersed in water as small droplets; the synthesis process is controllable, the performance is reliable, and the environment is friendly, and the emulsification process does not require acid adjustment.

Description

Technical Field

[0001] The invention belongs to the field of solid waste recycling and resource utilization and the technical field of road materials, and particularly relates to a waste grease-based emulsifier and a preparation method thereof. Background Art

[0002] Emulsified asphalt is playing an increasingly important role in road construction and maintenance due to its advantages, including energy conservation and environmental protection, ease of construction, superior performance, versatility, and economic benefits. Compared to hot asphalt, it conserves resources and energy, significantly reduces harmful emissions, and meets the requirements of sustainable development. Furthermore, emulsified asphalt can be applied at room temperature, enhancing construction flexibility and adaptability. Its excellent fluidity and permeability allow it to quickly fill cracks and potholes in the road surface, improving the smoothness and durability of the road surface.

[0003] Emulsified asphalt is prepared by leveraging the amphiphilic properties of emulsifiers. These emulsifiers reduce the interfacial tension between asphalt and water, allowing the asphalt droplets to be evenly dispersed throughout the water. However, currently used emulsifiers are expensive and have unreliable performance, increasing the trial-and-error and production costs of emulsified asphalt. Therefore, developing an emulsifier with a reliable synthesis pathway and high performance is crucial for promoting the application of emulsified asphalt.

[0004] Waste grease, also known as gutter oil, is a mixture of various triglycerides. In the presence of water, triglycerides undergo hydrolysis by breaking ester bonds to produce various fatty acids and glycerol. This makes them unsuitable for direct use or consumption, but through processing, they can be recycled and reused as a resource. Given the potential uses and environmental significance of waste cooking oil, the development of asphalt emulsifiers based on waste cooking oil has significant research value and broad application prospects. This emulsifier not only enhances the performance of emulsified asphalt by leveraging the abundant lipophilic groups in waste grease, but also promotes the resource utilization of waste, positively impacting environmental protection and sustainable development. In their study "Study and Characterization of a Novel Synthesis Method for Tall Oil Asphalt Emulsifier," Cai Guangnan et al. prepared a tall oil-based asphalt emulsifier using tall oil, polyethylene polyamine, epichlorohydrin, and trimethylamine as raw materials. However, the three-step preparation process is cumbersome and time-consuming. Moreover, trimethylamine has a strong irritating effect on the eyes, nose, throat and respiratory tract, and is one of the main sources of odor pollutants. Therefore, it is necessary to find a simple and green method for synthesizing asphalt emulsifiers. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a waste oil-based emulsifier and a preparation method thereof. The present invention proposes a two-step preparation process with a single rotary evaporation, which simplifies the preparation process and ensures that the emulsifier process is controllable and the performance is reliable.

[0006] The preparation method of the waste oil-based emulsifier is to use waste oil as raw material, adopt one or several combinations of diamine compounds for grafting modification, and obtain one or more primary amino compounds or secondary amino compounds, which are collectively referred to as amide intermediates, and then realize the final synthesis of the waste oil-based emulsifier through the ring-opening grafting of 2,3-epoxypropyltrimethylammonium chloride.

[0007] Specifically, to achieve the above objectives, the solution of the present invention is:

[0008] A method for preparing a waste oil-based emulsifier comprises the following steps:

[0009] (1) reacting waste oil and diamine compounds, using toluene as a water-carrying agent, and performing reflux reaction to obtain an amide intermediate;

[0010] (2) The amide intermediate and 2,3-epoxypropyltrimethylammonium chloride are refluxed under normal pressure, and the waste oil-based emulsifier is obtained after rotary evaporation.

[0011] In fact, the reaction mechanism is as follows:

[0012] Diamine compounds act as a bridge between waste oils and grease and 2,3-epoxypropyltrimethylammonium chloride, so diamine compounds act as a "bridge," gradually connecting and advancing the reaction through the multiple amino groups they contain. Diamine refers to an amine compound containing two amino groups in the molecule. The diamine molecules selected in the present invention contain at least two amino groups. The segments connected to one of the amino groups are denoted as R1 and R2, and the segments connected to the other amino group are denoted as R3 and R4. After the first amino group reacts, if there are still other amino groups on the corresponding R1 or R2 segment, these remaining amino groups will continue to react with the epoxy group to eventually produce the target product.

[0013] Specifically, the two-step mechanism of this process is as follows:

[0014] (I) The first step of grafting modification of waste oil-based emulsifiers is mainly the dehydration condensation of carboxylic acid and amino groups. Carboxylic acid (-COOH) comes from waste oil, and amino groups (-NH2) come from diamine compounds. The carboxylic acid carbon atom on the fatty acid is attacked by the nitrogen atom on the diamine, and the carbon-oxygen double bond is opened to form two hydroxyl groups. Subsequently, dehydration condensation quickly forms an amide intermediate. The specific reaction steps are shown in the figure below:

[0015] .

[0016] (II) The second step of graft modification of waste oil base mainly involves 2,3-epoxypropyltrimethylammonium chloride through a ring-opening reaction to complete the second step of graft modification. The other amino groups of the intermediate attack the epoxy group to cause a ring-opening reaction to obtain the final product, which is an amide cationic emulsifier. The specific reaction steps are shown in the figure below:

[0017] .

[0018] In step (1), the waste grease is selected from one or more of animal grease, vegetable grease, kitchen waste grease, and waste grease obtained through grease separation treatment.

[0019] The effective ingredients in waste oil are mainly glycerol and fatty acids obtained by hydrolysis of triglycerides. The fatty acids include one or more saturated fatty acids and unsaturated fatty acids represented by palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid, with a carbon chain length of 12 to 22.

[0020] The specific chemical formulas of some representative fatty acids in waste oils and fats are shown below:

[0021]

[0022] In step (1), the diamine compound refers to an amine compound containing two amino groups in the diamine molecule. The diamine compounds of the present invention include: ethylenediamine (EDA), piperazine (PIP) and hydroxyethylethylenediamine (AEEA).

[0023] Specifically, the piperazine molecule possesses two secondary amines (R2NH), which serve as a bridge connecting waste oil and 2,3-epoxypropyltrimethylammonium chloride. Due to its ring structure, piperazine-derived emulsifiers are less susceptible to deformation than chain-based emulsifiers, forming a tighter and more resilient interfacial film during asphalt emulsification. Furthermore, the π-π interactions between the ring structure and the abundant cyclic molecules in asphalt allow for tighter adsorption of the asphalt molecules on the asphalt surface, fully utilizing the emulsifier's ability to reduce interfacial tension between asphalt and water, resulting in optimal performance.

[0024] Among them, there is no order in which waste oils and diamine compounds are added to the round-bottom flask for modification (toluene does not participate in the reaction and is only used as a water-carrying agent to separate the water in the reaction system).

[0025] The lipophilic groups of the waste oil-based emulsifier come from fatty acids and glycerol of different chain lengths that are abundant in waste oil, and the hydrophilic groups come from the quaternary ammonium salt groups carried by 2,3-epoxypropyltrimethylammonium chloride.

[0026] Furthermore, in step (1), the reflux reaction temperature is 110-150° C. and the time is 1-5 h.

[0027] Furthermore, in step (1), the weight ratio of the diamine compound to the waste oil is 1:1-1:3.

[0028] Furthermore, in step (1) and step (2), the molar ratio of the diamine compound to 2,3-epoxypropyltrimethylammonium chloride is 1:2-2:1, preferably 1:1.

[0029] Furthermore, in step (2), the reflux reaction temperature is 75-95° C. and the time is 1-5 h.

[0030] Furthermore, in step (2), the rotary evaporation temperature is 40-60° C., the pressure is a negative pressure of 0.1 MPa, and the time is 0.5-1.5 h.

[0031] A waste grease-based emulsifier is dissolved in water to produce an emulsifier aqueous solution. This waste grease-based emulsifier has high emulsification efficiency and does not require acid adjustment during the preparation process. Asphalt is heated and melted, and the molten asphalt and the emulsifier aqueous solution are mixed and subjected to high-speed shearing in a shearing machine to produce emulsified asphalt.

[0032] The prepared emulsified asphalt is used in road materials.

[0033] The temperature of the asphalt is 120-150°C, more preferably 140°C.

[0034] The asphalt content is 50-80%, more preferably 60%.

[0035] The emulsifier content is 0.5-5%, more preferably 2%.

[0036] Due to the adoption of the above solution, the beneficial effects of the present invention are:

[0037] First, under the surface tension test conditions of 25°C, the emulsifier of the present invention can reduce the surface tension of water from 72.0 mN / m to 29.80-34.65 mN / m, with a reduction of 37.35-42.2 mN / m, indicating that the emulsifier effectively reduces the interfacial free energy and has good interfacial activity and emulsification efficiency. In the emulsified asphalt test with a solid content of 60%, both the 1d stability and the 5d stability meet the specification requirements, of which the 1d stability is 0.55% to 0.87%, which meets the specification requirement of less than 1%; the 5d stability is 3.57% to 4.41%, which meets the specification requirement of less than 5%, indicating that the emulsifier has good stability and excellent comprehensive performance. Therefore, the emulsifier prepared by the present invention and the emulsified asphalt prepared using the emulsifier can be widely used in road construction and maintenance. Second, the excellent emulsifying performance of the waste oil-based emulsifier synthesized by the present invention is due to the rich carbon chain of the waste oil, which has excellent lipophilicity. The quaternary ammonium salt group carried by 2,3-epoxypropyltrimethylammonium chloride gives the emulsifier excellent hydrophilicity. The emulsifier can disperse asphalt to form emulsified asphalt, in which asphalt serves as the dispersed phase and water serves as the continuous phase, and the asphalt is dispersed in the water in small droplets.

[0038] Third, the emulsifier of this invention effectively reduces the significant interfacial tension between water and asphalt, dispersing asphalt droplets in water and enabling the preparation of emulsified asphalt. Furthermore, thanks to the emulsifier's high emulsification efficiency, acid adjustment is not required during use, reducing acid corrosion on production equipment.

[0039] Fourthly, the present invention uses waste oils which are widely available and inexpensive, and recycles waste oils as waste resources, which contributes to low-carbon and environmental protection.

[0040] Fifth, the method of the present invention is simple, with two-step preparation and one-step rotary evaporation, and the reaction conditions are easy to control, and the process and performance are controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a surface tension curve of the emulsifier of Example 1 of the present invention.

[0042] Figure 2 This is the infrared spectrum of the emulsifier of Example 1 of the present invention.

[0043] Figure 3 This is a surface tension curve of the emulsifier of Example 2 of the present invention.

[0044] Figure 4 This is a surface tension curve of the emulsifier of Example 3 of the present invention.

[0045] Figure 5 This is a surface tension curve of the emulsifier of Example 4 of the present invention. DETAILED DESCRIPTION

[0046] The invention provides a waste oil-based emulsifier and a preparation method thereof.

[0047] The present invention will be further described below with reference to specific examples. However, the examples are intended to better illustrate the present invention and are not intended to limit the present invention in any way. All other examples obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0048] Example 1: (The diamine compound is piperazine PIP)

[0049] The preparation method of the waste oil-based emulsifier of this embodiment comprises the following steps:

[0050] (1) Waste oil and piperazine (PIP) were placed in a round-bottom flask at a weight ratio of 3:1. Toluene was added as a water-carrying agent at a weight ratio of 1:1 to waste oil. The reaction was carried out under normal pressure, at a reflux temperature of 150°C, and for 2 hours to obtain an intermediate product.

[0051] (2) Add 2,3-epoxypropyltrimethylammonium chloride in the same molar ratio as piperazine PIP in step (1) to the reaction. The reaction is carried out under normal pressure, the reaction temperature is 95°C, and the reflux reaction time is 1 hour.

[0052] (3) The emulsifier in step (2) was subjected to rotary evaporation at a temperature of 60°C, a pressure of 0.1 MPa, and a time of 1 hour to obtain the final emulsifier product.

[0053] The synthesis process is as follows:

[0054]

[0055]

[0056] like Figure 1 As shown, the emulsifier synthesized in this embodiment was prepared into solutions with different concentrations, and the concentration range was 1×10 -11 mg / L to 1×10 3 mg / L, the critical micelle concentration (CMC) of this emulsifier is 0.98 mg / L, and CMC corresponds to the surface tension γ CMC The value is 29.38 mN / m. This indicates that the emulsifier can significantly reduce the surface tension of the aqueous solution and has good interfacial activity and emulsification efficiency. In the preparation process of emulsified asphalt, the emulsifier concentration is usually higher than 1×10³ mg / L, generally 2×10 4mg / L, a concentration level that exceeds its critical micelle concentration (CMC). When the emulsifier concentration reaches the critical micelle concentration, the system achieves its lowest surface tension. Above this concentration, a tight molecular film forms at the asphalt / water interface within the emulsified asphalt, which has a large specific surface area. This effectively weakens the already significant interfacial tension between asphalt and water, creating conditions for the stable dispersion of asphalt droplets in the continuous water phase.

[0057] like Figure 2 As shown, the infrared spectrum of the emulsifier was collected using Bruker's ALPHA II compact FT-IR infrared spectrometer. The infrared spectrum showed the NH in-plane bending vibration absorption peak, the tertiary amide carbonyl C=O stretching vibration absorption peak, and the CN stretching vibration absorption peak. These are characteristic peaks of the synthetic waste oil-based emulsifier, indicating that the synthetic product is consistent with the target product. It should be added that Figure 2 The influence of other peaks is relatively low, and only analyzing the characteristic absorption peaks related to emulsifiers can meet the research needs.

[0058] To verify the actual application effect of the emulsifier, 2% of the emulsifier was dissolved in water to obtain an emulsifier aqueous solution without acid adjustment. The temperature of the emulsifier aqueous solution was maintained at 60°C. The asphalt was heated to 140°C to melt. The molten asphalt was mixed with the emulsifier aqueous solution and emulsified asphalt was obtained under high shear action of a colloid mill. The properties of the emulsified asphalt are shown in Table 1.

[0059] Example 2: (The diamine compound is ethylenediamine (EDA))

[0060] The preparation method of the waste oil-based emulsifier of this embodiment comprises the following steps:

[0061] (1) Waste oil and ethylenediamine (EDA) were placed in a round-bottom flask at a weight ratio of 3:1. Toluene was added as a water-carrying agent at a weight ratio of 1:1 to the waste oil. The reaction was carried out under normal pressure, with a reflux temperature of 130°C and a reaction time of 3 hours to obtain an intermediate product.

[0062] (2) Add 2,3-epoxypropyltrimethylammonium chloride in the same molar ratio as that of ethylenediamine (EDA) in step (1) to the reaction. The reaction is carried out under normal pressure, the temperature is maintained at 80°C, and the reflux reaction time is 2 hours.

[0063] (3) The emulsifier in step (2) was subjected to rotary evaporation at a rotary evaporation temperature of 60°C, a rotary evaporation pressure of 0.1 MPa, and a rotary evaporation time of 0.5 h to obtain a waste oil-based emulsifier.

[0064] The synthesis process is as follows:

[0065]

[0066]

[0067] like Figure 3 As shown, the emulsifier synthesized in this embodiment was prepared into solutions with different concentrations, and the concentration range was 1×10 -11 mg / L to 1×10 3 mg / L, the critical micelle concentration (CMC) of the emulsifier in this example is 0.55 mg / L, and CMC corresponds to the surface tension γ CMC The value is 33.53 mN / m. This indicates that the emulsifier can significantly reduce the surface tension of the aqueous solution and has good interfacial activity and emulsification efficiency. In the preparation process of emulsified asphalt, the emulsifier concentration is usually higher than 1×10³ mg / L, generally 2×10 4 mg / L, a concentration level that exceeds its critical micelle concentration (CMC). When the emulsifier concentration reaches the critical micelle concentration, the system achieves its lowest surface tension. Above this concentration, a tight molecular film forms at the asphalt / water interface within the emulsified asphalt, which has a large specific surface area. This effectively weakens the already significant interfacial tension between asphalt and water, creating conditions for the stable dispersion of asphalt droplets in the continuous water phase.

[0068] An emulsifier solution with a 2% content was dissolved in water without acid adjustment. The temperature of the emulsifier solution was maintained at 60°C. The asphalt was heated to 140°C to melt. The molten asphalt was mixed with the emulsifier solution and emulsified asphalt was obtained under high shear action of a colloid mill. The properties of the emulsified asphalt are shown in Table 1.

[0069] Example 3: (The diamine compound is hydroxyethylethylenediamine AEEA)

[0070] The preparation method of the waste oil-based emulsifier of this embodiment comprises the following steps:

[0071] (1) Waste oil and hydroxyethylethylenediamine (AEEA) were placed in a round-bottom flask at a weight ratio of 3:1. Toluene was added as a water-carrying agent at a weight ratio of 1:1 to the waste oil. The reaction was carried out under normal pressure, at a reaction temperature of 110°C, and at reflux for 5 hours to obtain an intermediate product.

[0072] (2) Add 2,3-epoxypropyltrimethylammonium chloride in the same molar ratio as that of hydroxyethylethylenediamine AEEA in step (1) to the reaction. The reaction is carried out under normal pressure, the reaction temperature is 75°C, and the reflux reaction time is 5 hours.

[0073] (3) The emulsifier in step (2) was subjected to rotary evaporation at a temperature of 60°C, a pressure of 0.1 MPa, and a time of 1 hour to obtain the final emulsifier product.

[0074] The synthesis process is as follows:

[0075]

[0076]

[0077] like Figure 4 As shown, the emulsifier synthesized in this embodiment was prepared into solutions with different concentrations, and the concentration range was 1×10 -11 mg / L to 1×10 3 mg / L, the critical micelle concentration (CMC) of the emulsifier in this example is 32.89 mg / L, and CMC corresponds to the surface tension γ CMC The value is 34.57 mN / m. This indicates that the emulsifier can significantly reduce the surface tension of the aqueous solution and has good interfacial activity and emulsification efficiency. In the preparation process of emulsified asphalt, the emulsifier concentration is usually higher than 1×10³ mg / L, generally 2×10 4 mg / L, a concentration level that exceeds its critical micelle concentration (CMC). When the emulsifier concentration reaches the critical micelle concentration, the system achieves its lowest surface tension. Above this concentration, a tight molecular film forms at the asphalt / water interface within the emulsified asphalt, which has a large specific surface area. This effectively weakens the already significant interfacial tension between asphalt and water, creating conditions for the stable dispersion of asphalt droplets in the continuous water phase.

[0078] An emulsifier solution with a 2% content was dissolved in water without acid adjustment. The temperature of the emulsifier solution was maintained at 60°C. The asphalt was heated to 140°C to melt. The molten asphalt was mixed with the emulsifier solution and emulsified asphalt was obtained under high shear action of a colloid mill. The properties of the emulsified asphalt are shown in Table 1.

[0079] Example 4: (The diamine compound is a combination of ethylenediamine EDA, piperazine PIP and hydroxyethylethylenediamine AEEA)

[0080] The preparation method of the waste oil-based emulsifier of this embodiment comprises the following steps:

[0081] (1) Waste oil and diamine compound were placed in a round-bottom flask at a weight ratio of 3:1, wherein the diamine compound was ethylenediamine EDA:piperazine PIP:hydroxyethylethylenediamine AEEA at a molar ratio of 1:1:1. Toluene was added as a water carrier at a weight ratio of 1:1 to the waste oil. The reaction was carried out under normal pressure, at a reflux reaction temperature of 130°C, and for 2 hours to obtain an intermediate product.

[0082] (2) Add 2,3-epoxypropyltrimethylammonium chloride in the same molar ratio as the diamine compound in step (1) to the reaction. The reaction is carried out under normal pressure, the temperature is maintained at 80°C, and the reflux reaction time is 1 hour.

[0083] (3) The emulsifier in step (2) was subjected to rotary evaporation at a rotary evaporation temperature of 40°C, a rotary evaporation pressure of 0.1 MPa, and a rotary evaporation time of 1.5 h to obtain a waste oil-based emulsifier.

[0084] like Figure 5 As shown, the emulsifier synthesized in this embodiment was prepared into solutions with different concentrations, and the concentration range was 1×10 -11 mg / L to 1×10 4 mg / L, the critical micelle concentration (CMC) of this emulsifier is 171.32 mg / L, and the surface tension γCMC corresponding to CMC is 31.32 mN / m. This shows that the emulsifier can significantly reduce the surface tension of the aqueous solution and has good interfacial activity and emulsification efficiency. In the preparation process of emulsified asphalt, the emulsifier concentration is usually higher than 1×10 4 mg / L, generally 2×10 4 mg / L, a concentration level that exceeds its critical micelle concentration (CMC). When the emulsifier concentration reaches the critical micelle concentration, the system achieves its lowest surface tension. Above this concentration, a tight molecular film forms at the asphalt / water interface within the emulsified asphalt, which has a large specific surface area. This effectively weakens the already significant interfacial tension between asphalt and water, creating conditions for the stable dispersion of asphalt droplets in the continuous water phase.

[0085] To verify the actual application effect of the emulsifier, 2% of the emulsifier was dissolved in water to obtain an emulsifier aqueous solution without acid adjustment. The temperature of the emulsifier aqueous solution was maintained at 60°C. The asphalt was heated to 140°C to melt. The molten asphalt was mixed with the emulsifier aqueous solution and emulsified asphalt was obtained under high shear action of a colloid mill. The properties of the emulsified asphalt are shown in Table 1.

[0086] Comparative Example 1:

[0087] The preparation method of the waste oil-based emulsifier in this comparative example is the same as that in Example 1, except that an acid adjustment process is performed.

[0088] 2% of the emulsifier prepared in Example 1 was dissolved in water to obtain an emulsifier aqueous solution, which was then acidified with hydrochloric acid to adjust the pH to 2. Furthermore, the temperature of the emulsifier aqueous solution was maintained at 60°C, and the asphalt was heated to 140°C to melt. The molten asphalt was mixed with the emulsifier aqueous solution, and emulsified asphalt was obtained under high shear action of a colloid mill. The properties of the emulsified asphalt are shown in Table 1.

[0089] Comparative Example 2: (The diamine compound is ethylenediamine EDA, and 2,3-epoxypropyltrimethylammonium chloride is not added)

[0090] Waste oil and ethylenediamine (EDA) were placed in a round-bottom flask at a weight ratio of 3:1. Toluene was added as a water carrier at a weight ratio of 1:1 to the waste oil. The reaction was carried out at atmospheric pressure, a temperature of 120°C, and a reflux reaction time of 2 hours to obtain intermediate product a.

[0091] The intermediate product with a content of 2% is dissolved in water to obtain an emulsifier aqueous solution. The temperature of the aqueous solution is maintained at 60°C. The asphalt is heated to 140°C to melt. The molten asphalt is mixed with the emulsifier aqueous solution and high-speed shearing is performed using a colloid mill.

[0092] The synthesis process is as follows:

[0093]

[0094] In the preparation of the emulsified asphalt in this comparative example, only the intermediate product was added, and a uniformly dispersed emulsified asphalt could not be obtained. The asphalt and water phases were separated during the preparation of the emulsified asphalt, so stability data and Zeta potential data could not be obtained. The participation of the intermediate product alone could not reduce the huge interfacial tension between water and asphalt.

[0095] Comparative Example 3: (No waste grease added)

[0096] Ethylenediamine (EDA) and 2,3-epoxypropyltrimethylammonium chloride were added to a round-bottom flask in a molar ratio of 1:1. The reaction was carried out at atmospheric pressure, 90°C, and refluxed for 2 hours to obtain intermediate product b.

[0097] The intermediate product with a content of 2% is dissolved in water to obtain an emulsifier aqueous solution. The temperature of the aqueous solution is maintained at 60°C. The asphalt is heated to 140°C to melt. The molten asphalt is mixed with the emulsifier aqueous solution and high-speed shearing is performed using a colloid mill.

[0098] In this comparative example, only ethylenediamine (EDA) and 2,3-epoxypropyltrimethylammonium chloride products cannot produce uniformly dispersed emulsified asphalt. The asphalt and water phases separate during the preparation process of the emulsified asphalt, so stability data and Zeta potential data cannot be obtained. The participation of only the intermediate product cannot reduce the huge interfacial tension between water and asphalt.

[0099] The synthesis process is as follows:

[0100]

[0101] Comparative Example 4: (without addition of diamine compound)

[0102] Waste oil and 2,3-epoxypropyltrimethylammonium chloride were added to a round-bottom flask in a weight ratio of 1:1. The reaction was carried out under normal pressure, at a temperature of 90°C, and under reflux for 3 hours to obtain intermediate product C.

[0103] Dissolve 2% of the intermediate product c in water to obtain an emulsifier aqueous solution. The temperature of the aqueous solution is maintained at 60°C. The asphalt is heated to 140°C to melt. The molten asphalt and the emulsifier aqueous solution are mixed and high-speed shearing is performed using a colloid mill.

[0104] In this comparative example, only waste oil and 2,3-epoxypropyltrimethylammonium chloride products cannot be used to obtain uniformly dispersed emulsified asphalt. The asphalt and water phases are separated during the preparation process of the emulsified asphalt, so stability data and Zeta potential data cannot be obtained. The participation of only intermediate products cannot reduce the huge interfacial tension between water and asphalt.

[0105] Comparative Example 5: (without addition of diamine compounds and 2,3-epoxypropyltrimethylammonium chloride)

[0106] 2% waste oil is dissolved in water to obtain an aqueous solution. The temperature of the aqueous solution is maintained at 60°C. The asphalt is heated to 140°C to melt. The molten asphalt is mixed with the aqueous solution and high-speed shearing is performed using a colloid mill.

[0107] In this comparative example, if only the reaction raw materials are added during the preparation of the emulsified asphalt, uniformly dispersed emulsified asphalt cannot be obtained. The asphalt and water phases separate during the preparation process of the emulsified asphalt, so stability data and Zeta potential data cannot be obtained. The participation of the reaction raw materials alone cannot reduce the huge interfacial tension between water and asphalt.

[0108] Comparative Example 6: (The diamine compound is ethylenediamine (EDA), and no waste oil or 2,3-epoxypropyltrimethylammonium chloride is added)

[0109] 2% ethylenediamine (EDA) was dissolved in water to obtain an aqueous solution, the temperature of the aqueous solution was maintained at 60°C, the asphalt was heated to 140°C to melt, the molten asphalt was mixed with the aqueous solution, and a colloid mill was used for high-speed shearing.

[0110] In this comparative example, the emulsified asphalt was prepared by adding only the reaction raw materials, and a uniformly dispersed emulsified asphalt could not be obtained. The asphalt and water phases separated during the preparation process of the emulsified asphalt, so stability data and Zeta potential data could not be obtained. The participation of the reaction raw materials alone could not reduce the huge interfacial tension between water and asphalt.

[0111] Comparative Example 7: (The diamine compound is piperazine PIP, and no waste oil or 2,3-epoxypropyltrimethylammonium chloride is added)

[0112] 2% piperazine PIP is dissolved in water to obtain an aqueous solution, the temperature of the aqueous solution is maintained at 60°C, the asphalt is heated to 140°C to melt, the molten asphalt and the aqueous solution are mixed, and a colloid mill is used for high-speed shearing.

[0113] In this comparative example, the emulsified asphalt was prepared by adding only the reaction raw materials, and a uniformly dispersed emulsified asphalt could not be obtained. The asphalt and water phases separated during the preparation process of the emulsified asphalt, so stability data and Zeta potential data could not be obtained. The participation of the reaction raw materials alone could not reduce the huge interfacial tension between water and asphalt.

[0114] Comparative Example 8: (The diamine compound is hydroxyethylethylenediamine AEEA, and no waste oil and 2,3-epoxypropyltrimethylammonium chloride are added)

[0115] 2% hydroxyethylethylenediamine AEEA is dissolved in water to obtain an aqueous solution, the temperature of the aqueous solution is maintained at 60°C, the asphalt is heated to 140°C to melt, the molten asphalt and the aqueous solution are mixed, and a colloid mill is used for high-speed shearing.

[0116] In the preparation of the emulsified asphalt in this comparative example, only the reaction raw materials were added, and uniformly dispersed emulsified asphalt could not be obtained. The asphalt and water phases separated during the preparation process of the emulsified asphalt, so stability data and Zeta potential data could not be obtained. The participation of the reaction raw materials alone could not reduce the huge interfacial tension between water and asphalt.

[0117] Comparative Example 9: (No waste oil and ethylenediamine compounds added)

[0118] 2% 2,3-epoxypropyltrimethylammonium chloride is dissolved in water to obtain an aqueous solution. The temperature of the aqueous solution is maintained at 60°C. The asphalt is heated to 140°C to melt. The molten asphalt and the aqueous solution are mixed and subjected to high-speed shearing using a colloid mill.

[0119] In the preparation of the emulsified asphalt in this comparative example, only the reaction raw materials were added, and uniformly dispersed emulsified asphalt could not be obtained. The asphalt and water phases separated during the preparation process of the emulsified asphalt, so stability data and Zeta potential data could not be obtained. The participation of the reaction raw materials alone could not reduce the huge interfacial tension between water and asphalt.

[0120] The following tests were performed on the emulsifiers in Examples 1-4 and Comparative Examples 1-9 and the emulsified asphalts prepared with the corresponding emulsifiers:

[0121] The SFT-D1 surface tension meter of Beijing Hako Company was used to measure the minimum critical micelle concentration (CMC) and CMC surface tension of emulsifier ( γ CMC ), where the critical micelle concentration (CMC) refers to the lowest concentration of emulsifier molecules in aqueous solution at which they begin to form stable micelles, marking the critical point at which the surface tension of the solution changes significantly. γ CMC) refers to the surface tension of the solution measured at the critical micelle concentration (CMC). It represents the lowest surface tension level that the emulsifier can achieve and is used to measure its ability to reduce surface tension.

[0122] According to T0652-1993 specified in JTG E20-2011 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", the evaporation residue content of emulsified asphalt, that is, the actual solid content of emulsified asphalt, is determined.

[0123] Storage stability was determined according to T0655-1993 of JTG E20-2011, "Test Procedures for Asphalt and Asphalt Mixtures for Highway Engineering." The difference in asphalt residue content in the upper and lower branches of the emulsified asphalt after one day (24 hours) and five days (120 hours) of storage was recorded, and recorded as the 1-day stability and 5-day stability, respectively. T0655-1993 of JTG E20-2011 requires that the 1-day and 5-day stability be less than 1% and 5%, respectively.

[0124] Zeta potential was measured using a JS94 Zeta potentiometer from Shanghai Zhongchen Digital Technology Equipment Co., Ltd. This instrument primarily measures electrophoretic mobility. Zeta potential is the potential difference at the sliding surface between the stern layer and the diffusion layer on the surface of an asphalt droplet in an emulsified asphalt system. It reflects the charge state of the asphalt droplet and its impact on the stability of the system.

[0125] Examples 1-4 produced waste oil-based emulsifiers with emulsifying properties, and the resulting emulsified asphalt was characterized. However, the emulsifier intermediates or reaction raw materials obtained in Comparative Examples 1-9 lacked emulsifying properties, making it impossible to prepare emulsified asphalt, and thus, no relevant performance test results were obtained.

[0126] The test results obtained from the above tests are shown in the following table.

[0127] Table 1 Performance determination of waste oil-based emulsifier and emulsified asphalt

[0128]

[0129] According to JTG E20-2011, "Test Procedures for Asphalt and Asphalt Mixtures for Highway Engineering," the permissible error for the Emulsified Asphalt Evaporation Residue Content Test (T 0651-1993) is 0.4% for repeatability testing and 0.8% for reproducibility testing. The actual solids content of the emulsified asphalt described above was within this tolerance.

[0130] The experimental results of Examples 1-4 and Comparative Example 1 demonstrate that the emulsified asphalts of Examples 1-4 exhibit excellent stability, thanks to the long-chain product formed from waste oil, diamine compounds, and 2,3-epoxypropyltrimethylammonium chloride, which carries more hydrophilic and lipophilic groups. All Examples 1-4 meet the stability requirements of T0655-1993, as specified in the JTG E20-2011 test procedure, and all exhibit Zeta potentials exceeding 70 mV. Example 1 achieves a Zeta potential of 86.79 mV, demonstrating the reliable emulsification and superior performance of the emulsifiers of Examples 1-4, with Example 1 showing particularly outstanding performance. The waste oil-based emulsifier of Comparative Example 1 is prepared using the same method as Example 1, and the CMC and γcmc values ​​of Comparative Example 1 and Example 1 are identical. Comparative Example 1 undergoes an acidification treatment compared to Example 1; it should be noted that acidification treatment is not recommended for the emulsifiers disclosed herein. Typically, the hydrogen ion concentration in the solution is increased by adjusting the acidity, which promotes the full ionization of basic groups such as amine groups in the cationic asphalt emulsifier molecules, thereby improving emulsification efficiency. However, the cationic groups in the emulsifier molecules prepared by the present invention are fully ionized under the basic pH environment of the emulsifier, without the need for additional acidic environment assistance, and already possess efficient and stable emulsification performance. Furthermore, the acidity adjustment operation will disrupt the adsorption equilibrium between the emulsifier molecules prepared by the present invention and the asphalt particles, not only failing to improve the emulsification effect, but also reducing the emulsion stability and affecting the normal performance of the emulsification performance.

[0131] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a waste oil-based emulsifier, characterized in that: It includes the following steps: (1) reacting waste oil and diamine compounds, using toluene as a water-carrying agent, and performing reflux reaction to obtain an amide intermediate; (2) subjecting the amide intermediate and 2,3-epoxypropyltrimethylammonium chloride to reflux reaction under normal pressure, and obtaining a waste oil-based emulsifier after rotary evaporation; In step (1), the waste grease is selected from one or more of animal grease, vegetable grease, kitchen waste grease, and waste grease obtained from oil separation treatment; The effective components in the waste oil and fat are mainly glycerol and fatty acids obtained by hydrolysis of triglycerides, and the fatty acids include one or more of palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid, with a carbon chain length of 12 to 22; In step (1), the diamine compound is selected from one or more of hydroxyethylethylenediamine, ethylenediamine or piperazine; In step (1), the reflux reaction temperature is 110-150°C and the time is 1-5h; In step (1), the weight ratio of the diamine compound to the waste oil is 1:1-1:3; In step (2), the reflux reaction temperature is 75-95°C and the time is 1-5 hours; In step (2), the rotary evaporation temperature is 40-60°C, the pressure is a negative pressure of 0.1 MPa, and the time is 0.5-1.5 hours; In step (1) and step (2), the molar ratio of the diamine compound to 2,3-epoxypropyltrimethylammonium chloride is 1:2-2:

1.

2. The method for preparing a waste oil-based emulsifier according to claim 1, wherein: The waste grease is 100 parts by weight, the diamine compound is 30-60 parts by weight, and the 2,3-epoxypropyltrimethylammonium chloride is 30-60 parts by weight.

3. A waste oil-based emulsifier, characterized in that: The product is obtained by the preparation method according to claim 1 or 2.

4. A method for preparing emulsified asphalt, characterized in that: The waste oil-based emulsifier according to claim 3 is dissolved in water to obtain an emulsifier aqueous solution, and then the molten asphalt and the emulsifier aqueous solution are mixed to obtain emulsified asphalt under shearing action.

5. An emulsified asphalt, characterized in that: It is obtained by the preparation method described in claim 4.

6. Use of the emulsified asphalt according to claim 5 in road materials.

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