Sustainable asphalt regenerant, preparation method and application

Abstract

The invention discloses a sustainable asphalt regenerant, a preparation method and application, the sustainable asphalt regenerant comprises methyl palmitate, methyl linoleate, methyl oleate, methyl stearate, methyl eicosenoate, methyl arachidonate and the like, the content of saturated fatty acid methyl ester exceeds 21.3-25.6% of the total content of fatty acid methyl ester, and the content of saturated fatty acid methyl ester exceeds 21.3-25.6% of the total content of fatty acid methyl ester. The content of unsaturated fatty acid methyl ester exceeds 66.2-70.5% of the total content of fatty acid methyl ester, and the total fraction is 100%; the regenerant is prepared from waste edible oil and fat as a raw material, and compared with a traditional petroleum-based regenerant, the regenerant is wide in source, low in raw material cost and renewable. The sustainable asphalt regenerant can effectively recover various properties of aged asphalt, and solves the problems of poor water damage resistance and durability caused by high content of acidic compounds in the existing waste edible oil asphalt regenerant; meanwhile, the recovery and reutilization of the waste edible grease and the aged asphalt material are realized.

Description

Technical Field

[0001] This invention belongs to the field of asphalt recycling technology, specifically relating to a sustainable asphalt recycler, its preparation method, and its application. Background Technology

[0002] After being put into operation, asphalt pavements are subjected to the interaction of environmental and traffic loads, causing their mechanical properties to gradually deteriorate. Therefore, regular maintenance and repair are usually required. For pavements with severe rutting or cracking, milling and reconstruction of the original pavement are necessary, generating a large amount of old material. If this old material is not properly disposed of, it means occupying a large amount of land resources and may even pollute the environment. Asphalt pavement recycling technology can regenerate and reuse the aforementioned old material, offering high economic and environmental benefits and has always been a research hotspot in the field of road engineering.

[0003] Traditional petroleum-based asphalt recycling agents contain carcinogenic polycyclic aromatic hydrocarbons and are derived from petroleum, a non-renewable resource, thus contradicting current environmental protection and sustainable development principles. Waste cooking oil, with a similar chemical composition to asphalt and significantly lower cost, has gradually come into focus. A large amount of waste cooking oil is generated globally each year. This waste cooking oil contains high levels of heavy metals, bacteria, and viruses. Improper disposal methods can lead to serious negative environmental impacts. Therefore, how to efficiently utilize waste cooking oil has always been a hot topic and an urgent problem to be solved.

[0004] Currently, scholars both domestically and internationally have conducted extensive research on the recycling of aged asphalt materials using waste edible oils, confirming the recycling potential of waste edible oils for aged asphalt materials. However, existing waste edible oil asphalt recycling technologies only involve routine pretreatment of the collected waste edible oils (such as drying and impurity removal) or direct use in the recycling of aged asphalt materials without any treatment. This ignores the increased acidic compounds due to the incorporation of waste edible oils, which significantly increases the moisture sensitivity of the recycled asphalt pavement, thereby reducing its durability. Therefore, in order to reduce or remove acidic compounds in waste edible oils and significantly improve the water damage resistance and durability of recycled asphalt pavements, it is urgent to develop a highly efficient and sustainable asphalt recycling agent. This will facilitate the resource utilization of waste edible oils in the recycling of aged asphalt materials.

[0005] Chinese invention patent application CN111073321A discloses an asphalt mortar based on waste edible oil recycling and its preparation method. The method is characterized by comprising aged asphalt mortar and a waste edible oil recycling agent, wherein the amount of waste edible oil recycling agent added is 7-8% of the mass of asphalt in the aged asphalt mortar. Although the waste edible oil is purified and dehydrated, the resulting waste edible oil recycling agent contains a large amount of acidic compounds, which negatively impacts the water damage resistance and durability of the recycled asphalt. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems existing in the prior art and provide a method for preparing a sustainable asphalt recycler from waste edible oils. This sustainable asphalt recycler can effectively restore the various properties of aged asphalt, solving the problem of poor water damage resistance and durability caused by the high content of acidic compounds in existing waste edible oil asphalt recyclers, and realizing the simultaneous recycling and reuse of waste edible oils and aged asphalt materials.

[0007] According to a first aspect of the present invention, a sustainable asphalt recycler is provided, the sustainable asphalt recycler comprising methyl palmitate, methyl linoleate, methyl oleate, methyl stearate, methyl eicosenoate, methyl arachidate, etc., wherein saturated fatty acid methyl esters exceed 21.3-25.6% of the total fatty acid methyl ester content, and unsaturated fatty acid methyl esters exceed 66.2-70.5% of the total fatty acid methyl ester content, calculated on a total basis of 100%; The regenerant is prepared from waste edible oil.

[0008] Based on the above technical solution, the density of the sustainable asphalt recycling agent is 892~932 kg / m³. 3 The acid value is 0.16~0.32 mg KOH / g, the free fatty acid content is 0.08~0.16%, and the calorific value is 38.62~39.70 MJ / kg.

[0009] According to a second aspect of the present invention, a method for preparing a sustainable asphalt recycling agent is provided, comprising the following steps: Step 1, Pre-treatment of waste cooking oil; Step 2, Preparation of pre-esterified oil: The waste edible oil pretreated in Step 1, methanol, and concentrated sulfuric acid are mixed, reacted, allowed to stand and separated, the lower phase is rotary evaporated, washed with hot distilled water until the pH is neutral, and water is removed to obtain pre-esterified oil. Step 3, Preparation of sustainable asphalt recycler: Mix methanol and potassium hydroxide, then add the pre-esterified oil obtained in step 2, react II, let stand and separate the liquids, rotary evaporate the lower phase liquid, wash with hot distilled water until the pH is neutral, remove water, and obtain sustainable asphalt recycler.

[0010] Based on the above technical solution, the pretreatment of waste edible oil in step 1 includes vacuum filtration to remove impurities and vacuum drying to remove water.

[0011] Based on the above technical solution, the pretreatment of waste cooking oil in step 1 is as follows: the waste cooking oil is vacuum filtered (to remove food residue) using double-layer filter paper (double-layer Whatman Grade 4 standard qualitative filter paper, with a diameter of 125 mm and a pore size of 20~25 μm), and then dried in a drying oven at 100~105℃ for 0.5~1 h. The waste cooking oil is weighed every 10 min until there is no significant change in quality.

[0012] Based on the above technical solution, the molar ratio of methanol to the waste edible oil pretreated in step 1 in step 2 is 6:1 to 10:1; The amount of concentrated sulfuric acid used is 0.5-1% of the mass of the waste edible oil pretreated in step 1.

[0013] Based on the above technical solution, the molar ratio of methanol to the waste edible oil pretreated in step 1 in step 2 can be independently selected from any value among 6:1, 6.5:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1, and 10:1 or the range between any two of the above points.

[0014] Based on the above technical solution, the conditions for reaction I in step 2 are as follows: The temperature of reaction I is 50~60℃; The reaction time for reaction I is 1-2 hours; The stirring speed for reaction I is 400~800 rpm; The conditions for reaction II in step 3 are the same as those for reaction I in step 2.

[0015] Based on the above technical solution, the temperature of rotary evaporation in step 2 is 45~50℃; The rotary evaporation time is 0.5~1h; The temperature of the hot distilled water in step 2 is 70~80℃.

[0016] Based on the above technical solution, the molar ratio of methanol to the pre-esterified oil prepared in step 2 in step 3 is 6:1 to 10:1; In step 3, the amount of potassium hydroxide used is 0.5-1% of the mass of the pre-esterified oil prepared in step 2; In step 3, the liquid is allowed to stand and separate, the lower phase is evaporated by rotary evaporation, and the liquid is washed with hot distilled water until the pH is neutral. The dehydration process is the same as in step 2.

[0017] According to a third aspect of the present invention, a sustainable asphalt rejuvenator is provided for use in the restoration of aged asphalt.

[0018] Beneficial effects (1) The sustainable asphalt regenerator of the present invention uses waste edible oil as raw material. Compared with traditional petroleum-based regenerators, it has a wide range of sources, low raw material cost, and is renewable.

[0019] (2) The sustainable asphalt regenerator prepared by this invention has stable properties and can be stored for a long time, avoiding the problem of oxidative rancidity that easily occurs when waste edible oil is stored, and solving the problems of poor water resistance and poor durability of waste edible oil. In addition, it can significantly improve the various properties of aged asphalt.

[0020] (3) The preparation method of the sustainable asphalt recycler provided by the present invention is simple, cost is well controlled, and the effect is significant. Under optimal reaction conditions, the content of acidic compounds in waste edible oil is reduced by more than 92%.

[0021] In summary, this invention utilizes a two-step chemical reaction to significantly reduce the acidic compound content of waste edible oils, thereby enhancing their regeneration effect on aged asphalt and overcoming the shortcomings of existing waste edible oil asphalt regeneration technologies. The widespread application of this invention has significant practical implications for achieving the efficient recycling of waste edible oils and aged asphalt materials. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of the preparation method of the sustainable asphalt recycling agent described in Example 1 of the present invention.

[0023] Figure 2 This is the Fourier transform infrared spectrum of the sustainable asphalt recycling agent described in Example 1 of the present invention. Detailed Implementation

[0024] To make the objectives and technical solutions of this invention clearer, the following embodiments are provided for further explanation. However, the scope of protection of this invention is not limited to these embodiments; the embodiments are merely for illustrative purposes. Those skilled in the art should understand that any changes or equivalent substitutions that do not depart from the concept of this invention are included within the scope of protection of this invention.

[0025] Unless otherwise specified, all reagents and raw materials used in this invention are obtained through purchase.

[0026] In the embodiments and comparative examples of this invention, the untreated aged asphalt was subjected to an 85-minute rotating thin film oven heating test (RTFOT) and a 20-hour pressure aging vessel accelerated asphalt aging test (PAV) in accordance with JTG E20-2011 to obtain aged asphalt. The base asphalt used was Grade 90 A base asphalt, and all properties met the requirements of the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011).

[0027] Example 1 Step 1, Pretreatment of waste cooking oil: The collected waste cooking oil was vacuum filtered using double-layer Whatman Grade 4 standard qualitative filter paper (125 mm in diameter, 20-25 μm pore size) to remove food residue. The filtered waste cooking oil was placed in a beaker and then placed in a vacuum drying oven at 105°C for 1 hour to dry and dehydrate. Finally, dry and clear waste cooking oil was obtained.

[0028] Step 2, Preparation of pre-esterified oil: A 250 mL three-necked flask equipped with a magnetic stirrer, thermometer, and condenser was placed in a constant-temperature oil bath. 50 g of the waste edible oil obtained in step (1) was added, and the mixture was heated to 52 °C. Simultaneously, 15.496 g of methanol (molar ratio of methanol to waste edible oil was 8:1) and 0.375 g of concentrated sulfuric acid (0.75% of the mass of waste edible oil) were heated at 52 °C for 5 min, and then slowly added to the flask. Immediately afterwards, the speed controller was adjusted to keep the stirring speed constant at 600 rpm, and the condenser was turned on, marking the start of the chemical reaction. After the mixture reacted at a constant temperature of 52 °C for 1.5 h, heating and stirring were stopped. After the reaction system cooled to room temperature, the liquid mixture was poured into a separatory funnel and allowed to stand for separation. After overnight, the lower phase was separated from the lower end of the separatory funnel and collected. The unreacted methanol in the lower phase oil was removed by a rotary evaporator under vacuum at 45 °C. The oil is then repeatedly washed with distilled water at 70 °C until the pH of the wash water is close to neutral to remove the catalyst. Finally, trace amounts of water in the oil are removed with anhydrous sodium sulfate. This yields a pre-esterified oil suitable for alkaline transesterification reactions.

[0029] Step 3, Preparation of Sustainable Asphalt Recycling Agent: Weigh 19.615g of methanol (molar ratio of methanol to pre-esterified oil is 9:1) and 0.512g of potassium hydroxide (1% of the mass of pre-esterified oil), place them in a ground glass flask, heat for about 5 minutes under the action of a magnetic stir bar to completely dissolve the potassium hydroxide, and then slowly pour it into the pre-esterified oil obtained in step (2), reacting at 55 ℃ for 1 h. Use the same reaction apparatus, stirring and condensation conditions as in step (2). After the reaction is complete, let it stand in a separatory funnel to separate the layers. After overnight, separate the upper phase from the top of the separatory funnel and collect it. Then, remove methanol from the upper liquid phase obtained after separation according to the method provided in step (2), and then remove the catalyst according to the water washing method provided in step (2) until the washing water is clear and transparent and the pH is close to neutral. Finally, add anhydrous sodium sulfate and dry to obtain the sustainable asphalt recycling agent. The process flow diagram of the sustainable asphalt recycling agent is shown in [link to process flow diagram]. Figure 1 .

[0030] The Fourier transform infrared spectrum of the sustainable asphalt recycling agent prepared in Example 1 is shown below. Figure 2 As shown. 1436 cm -1 and 1196 cm -1 The absorption peaks at these locations are mainly the result of the stretching vibrations of -CH3 and O-CH3. These two prominent peaks indicate a high methyl ester content in the sustainable asphalt recycler, proving that free fatty acids are converted into fatty acid methyl esters.

[0031] The following describes the performance testing of the sustainable asphalt recycling agent prepared in Example 1.

[0032] (1) The performance test results of the sustainable asphalt recycling agent prepared in Example 1 are shown in Table 1.

[0033] Table 1 shows the performance test results of the sustainable asphalt recycling agent described in Example 1.

[0034] (2) The relative content test results of the main chemical components in the sustainable asphalt rejuvenator prepared in Example 1 are shown in Table 2.

[0035] Table 2 shows the chemical composition of the sustainable asphalt recycling agent in Example 1.

[0036] (3) Performance test results of recycled asphalt binder A sustainable asphalt rejuvenator was applied to the recycled asphalt binder. In the recycled asphalt binder, the sustainable rejuvenator prepared in Example 1 was added at 7% of the aged asphalt (untreated) by mass fraction. The penetration, softening point, and rotational viscosity of the recycled asphalt binder were measured, and the results are shown in Table 3.

[0037] Table 3 shows the performance test results of recycled asphalt binder.

[0038] Example 2 The difference from Example 1 is that the molar ratio of methanol to waste edible oil is different in step 2, which is 10:1. The remaining steps are the same as in Example 1, resulting in a sustainable asphalt regenerator.

[0039] Example 3 The difference from Example 1 is that the molar ratio of methanol to pre-esterified oil in step 3 of the preparation of the sustainable asphalt recycler is different, namely 8:1. The remaining steps are the same as in Example 1, and a sustainable asphalt recycler is obtained.

[0040] Comparative Example 1 The difference from Example 1 is that only the waste cooking oil was pretreated (step 1 in Example 1), and no other steps were required.

[0041] The following describes the performance tests conducted on the waste cooking oil of Comparative Example 1.

[0042] (1) The performance test results of waste edible oil in Comparative Example 1 are shown in Table 4.

[0043] Table 4

[0044] Comparing Tables 1 and 4, it can be seen that after treating waste edible oils using the optimal technical solution provided by this invention, the acid value / free fatty acid content is reduced by 92.2%, demonstrating the significant advantages of this invention in the treatment of waste edible oils to reduce acidity.

[0045] (2) The relative content test results of the main chemical components in the waste edible oil of Comparative Example 1 are shown in Table 5.

[0046] Table 5

[0047] Comparing Tables 2 and 5, it can be seen that the vast majority of free fatty acids in waste edible oils were successfully methylated. Table 2 shows that the total methyl ester content of the sustainable asphalt recycler is greater than 91.77%, proving that the treatment method proposed in this invention has extremely high conversion efficiency. Furthermore, the efficient conversion of free fatty acids into fatty acid methyl esters also provides a scientific explanation for the decrease in acid value / free fatty acid content after the reaction.

[0048] (3) Performance test results of recycled asphalt binder Waste edible oils were applied to the recycled asphalt binder. The amount of regenerator added to the recycled asphalt binder was 7% of the aged asphalt (untreated) by mass fraction. The penetration, softening point, and rotational viscosity of the recycled asphalt binder were measured, and the results are shown in Table 6.

[0049] Table 6

[0050] Comparing Tables 3 and 6, it can be seen that the penetration of recycled asphalt from waste edible oil is smaller, the softening point is higher, and the rotational viscosity is larger, indicating that compared with sustainable asphalt recyclers, waste edible oil has a poorer effect on restoring the performance of aged asphalt.

[0051] Comparative Example 2 The difference from Example 1 is that only aged asphalt (untreated) is used.

[0052] The penetration, softening point and rotational viscosity of the aged asphalt (untreated) of Comparative Example 2 were tested below, and the results are shown in Table 7.

[0053] Table 7

[0054] Comparing Tables 3 and 7, it can be seen that the addition of sustainable asphalt recycling agents to aged asphalt increases the penetration of aged asphalt, reduces the softening point and rotational viscosity of aged asphalt, and significantly restores the rheological properties of aged asphalt.

[0055] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A sustainable asphalt rejuvenator, characterized in that, The sustainable asphalt regenerant comprises methyl palmitate, methyl linoleate, methyl oleate, methyl stearate, methyl eicosanoate, methyl arachidate, etc., wherein the content of saturated fatty acid methyl ester is 21.3-25.6% of the total fatty acid methyl ester content, and the content of unsaturated fatty acid methyl ester is 66.2-70.5% of the total fatty acid methyl ester content, based on a total score of 100%; The regenerant is prepared from waste edible oil and fat.

2. The sustainable asphalt rejuvenator of claim 1, wherein, The density of the sustainable asphalt regenerant is 892~932 kg / m 3 , the acid value is 0.16~0.32 mg KOH / g, the free fatty acid content is 0.08~0.16%, and the heat value is 38.62~39.70 MJ / kg.

3. The method for producing a sustainable asphalt recycling agent according to any one of claims 1 to 2, characterized by, The method comprises the following steps: Step 1: pretreatment of waste edible oil and fat; Step 2: preparation of pre-esterified oil: the waste edible oil and fat pretreated in step 1, methanol and concentrated sulfuric acid are mixed, reaction I, standing and separating, phase liquid is removed by rotary evaporation, hot distilled water is washed until the pH is neutral, water is removed, and pre-esterified oil is obtained; Step 3: preparation of sustainable asphalt regenerant: methanol and potassium hydroxide are mixed, and the pre-esterified oil obtained in step 2 is added, reaction II, standing and separating, phase liquid is removed by rotary evaporation, hot distilled water is washed until the pH is neutral, water is removed, and sustainable asphalt regenerant is obtained.

4. The production method according to claim 3, characterized by, The waste edible oil and fat pretreatment in step 1 is specifically: vacuum filtration of waste edible oil and fat with double-layer filter paper, drying in a 100-105℃ drying box for 0.5-1h, and weighing the waste edible oil and fat every 10min until the mass does not change significantly.

5. The preparation method according to claim 3, characterized in that, The molar ratio of methanol to the waste edible oil and fat pretreated in step 1 is 6:1-10:1 in step 2. The amount of concentrated sulfuric acid is 0.5-1% of the mass of the waste edible oil and fat pretreated in step 1.

6. The preparation method according to claim 3, characterized in that, The conditions of reaction I in step 2 are as follows: The temperature of reaction I is 50-60℃; The time of reaction I is 1-2h; The stirring speed of reaction I is 400-800rpm; The conditions of reaction II in step 3 are the same as those of reaction I in step 2.

7. The preparation method according to claim 3, characterized in that, The temperature of rotary evaporation in step 2 is 45-50℃; The time of rotary evaporation is 0.5-1h; The temperature of hot distilled water in step 2 is 70-80℃.

8. The preparation method according to claim 3, characterized in that, The molar ratio of methanol to the pre-esterified oil prepared in step 2 is 6:1-10:1 in step 3. The amount of potassium hydroxide is 0.5-1% of the mass of the pre-esterified oil prepared in step 2 in step 3. The standing and separating, phase liquid removal by rotary evaporation, hot distilled water washing until the pH is neutral, and water removal process in step 3 are the same as those in step 2.

9. The sustainable asphalt regenerant prepared by the preparation method of any one of claims 3-8 is used in aging asphalt recovery.

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