Water solution surface energy parameter testing method based on surface and interface tension method

Abstract

The invention relates to the technical field of road engineering, in particular to an aqueous solution surface energy parameter testing method based on a surface and interface tension method, which comprises the following steps: firstly, carrying out surface tension testing on a to-be-tested aqueous solution to obtain a surface tension coefficient of the to-be-tested aqueous solution; then selecting two organic reagents, respectively adding the two organic reagents into the two aqueous solutions to be tested, fully standing to form two different organic reagent-aqueous solution contact interfaces, respectively carrying out interfacial tension tests on the two interfaces, and obtaining interfacial tension coefficients of the contact interfaces of the aqueous solutions to be tested and the two organic reagents; and finally, substituting the surface tension coefficient, the two interfacial tension coefficients and the known surface energy parameters of the two organic reagents into an equation set based on a GvOC model, and solving and determining the surface energy parameters of the aqueous solution to be detected. According to the invention, the surface energy parameters of aqueous solutions with different pH values can be accurately tested, so that the water stability of the asphalt mixture in water environments with different pH values can be accurately and quantitatively evaluated.

Description

Technical Field

[0001] The invention relates to the technical field of road engineering, in particular to a method for testing surface energy parameters of an aqueous solution based on a surface interfacial tension method. Background Art

[0002] Under actual service conditions, asphalt pavement is exposed to the natural environment for a long time and is inevitably subject to water erosion. The pH value of the water environment in which the asphalt mixture is located is not always constant at 7.0. Acidic and alkaline water environments will react physically and chemically with the asphalt and aggregates in the asphalt mixture, accelerating or delaying the peeling of the asphalt film on the aggregate surface. Therefore, studying the water stability of asphalt mixtures in a neutral water environment with a pH of 7.0 cannot objectively and truly reflect the degree of influence of water on water damage to asphalt mixtures. In addition, since the asphalt mixture water stability model that considers the acidity and alkalinity of the water environment has not yet been developed, the existing test methods cannot accurately quantify the water stability of asphalt mixtures in actual service environments.

[0003] Surface energy theory believes that the change in the Gibbs free energy of the system when solid-liquid two-phase materials are in contact can reflect the adhesion characteristics of the solid-liquid interface, which can be obtained by calculating the surface energy parameters of the material. With the continuous development of surface energy theory, it has been widely used to quantitatively evaluate the water stability of asphalt mixtures. However, most studies only examine the water stability of asphalt mixtures in a neutral water environment. Therefore, there is an urgent need for a reasonable and reliable surface energy test method to accurately determine the surface energy parameters of aqueous solutions with different pH values, so as to quantitatively evaluate the effect of the pH value of the water environment on the water stability of asphalt mixtures. Summary of the invention

[0004] In order to address the deficiencies in the prior art, the present invention provides a method for testing the surface energy parameters of aqueous solutions based on the surface tension method, which can accurately test the surface energy parameters of aqueous solutions with different pH values, thereby accurately and quantitatively evaluating the water stability of asphalt mixtures in water environments with different pH values.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for testing surface energy parameters of aqueous solution based on surface interfacial tension method, comprising the following steps:

[0006] S1. Install the pretreated platinum plate on the balance fixture of the surface tension meter;

[0007] S2, placing a container containing the aqueous solution to be tested on the lifting platform of the surface tension meter, immersing the temperature probe in the aqueous solution to be tested, and controlling the temperature of the aqueous solution to be tested by a constant temperature system;

[0008] S3. When the temperature of the aqueous solution to be tested is constant at the test temperature, lift the lifting platform until the surface of the aqueous solution to be tested is about to touch the bottom of the pre-treated platinum plate. Read the balance reading after it stabilizes. Continue to slowly lift it 2mm. Read the balance reading after it stabilizes. Calculate the surface tension coefficient

[0009] S4, repeat steps S1-S2, lift the lifting platform until the bottom of the pre-treated platinum plate is about to touch the surface of the aqueous solution to be tested, and read the balance reading after it stabilizes;

[0010] S5. Inject the organic reagent into the container in step S4, and let it stand until the organic reagent and the aqueous solution to be tested form a stable interface. Then continue to slowly lift the lifting platform until the organic solvent completely immerses the platinum plate. After stabilization, read the balance reading. Combined with the balance reading read in step S4, calculate the interfacial tension coefficient γ WL ;

[0011] There are two kinds of organic reagents, both of which are used alone. The interfacial tension coefficient obtained by using the first organic reagent is recorded as γ WL(1) ; Using the second organic reagent, the interfacial tension coefficient is recorded as γ WL(2) ;

[0012] S6. γ WL(1) , γ WL(2) , and the known surface energy parameters of the two organic reagents and and Substituting into the equations based on the Good-van Oss-Chadury (GvOC) model, the three basic components of the surface energy of the aqueous solution to be tested are obtained: and

[0013] Preferably, in step S1, the pretreated platinum plate is prepared by sequentially washing the platinum plate with acetone, distilled water, and acetone, and then drying the plate.

[0014] Preferably, in step S2, the pH of the aqueous solution to be tested is 3.0-11.0.

[0015] Preferably, in step S2, the aqueous solution to be tested is 60 ml; the temperature of the aqueous solution to be tested is controlled to be 20±0.1° C., and the temperature stabilization time should be no less than 10 min.

[0016] Preferably, in step S3, the surface tension coefficient of the aqueous solution to be tested is The calculation principle is to use the property of the pre-treated platinum plate that it can completely wet the aqueous solution. Before being immersed in the aqueous solution, the balance reading is F1; after being immersed in the aqueous solution, the balance reading is F2. Record the balance reading difference ΔF1=F1-F2, and calculate the surface tension coefficient of the aqueous solution by the following formula, where P t V is the perimeter of the surface of the platinum plate intercepted by the aqueous solution surface. im represents the volume of the platinum plate immersed in the aqueous solution, ρ L1 represents the density of aqueous solution, ρ air represents the air density and g represents the acceleration due to gravity.

[0017]

[0018] Preferably, in step S5, the interfacial tension coefficient γ of the contact interface between the aqueous solution to be tested and the organic reagent is WL The calculation principle is to use the property of pre-treated platinum plate that it can be completely wetted. Before the platinum plate is immersed in the aqueous solution, the balance reading is F3; after immersion in the aqueous solution, the balance reading is F4. Record the balance reading difference ΔF2 = F3-F4, and calculate the interfacial tension coefficient between the aqueous solution and the organic reagent by the following formula, where P t represents the perimeter of the surface of the platinum plate intercepted by the interface between the aqueous solution and the organic reagent, V represents the volume of the platinum plate, and V jm represents the volume of the platinum plate immersed in the aqueous solution, ρ L1 represents the density of aqueous solution, ρ L2 represents the density of the organic reagent, ρ air represents the air density and g represents the acceleration due to gravity.

[0019]

[0020] Preferably, in step S5, the organic reagent is a water-insoluble organic reagent having a density less than that of water, which includes n-hexane and toluene.

[0021] Preferably, in steps S3 and S5, the surface tension coefficient Interfacial tension coefficient γ WL(1) and γ WL(2) All the results are obtained by taking the average value after multiple tests.

[0022] Preferably, in step S6, the and The surface energy non-polar component, polar acid component and polar base component of the first organic reagent; and is the nonpolar component, polar acid component and polar base component of the surface energy of the second organic reagent; and It is the non-polar component, polar acid component and polar base component of the surface energy of the aqueous solution to be tested.

[0023] Preferably, in step S6, the equation group based on the GvOC model is:

[0024]

[0025] The present invention provides a method for testing surface energy parameters of aqueous solutions based on the surface interfacial tension method, which has the following beneficial effects compared with the prior art:

[0026] The present invention provides a method for testing the surface energy parameters of aqueous solutions based on the surface / interfacial tension method, which can accurately test the surface energy parameters of aqueous solutions with different pH values; on this basis, the surface energy parameters of asphalt and aggregate are combined to calculate the adhesion binding energy of asphalt-aggregate in water environments with different pH values, so as to explore the influence of pH value on the surface energy parameters of water and the binding energy of asphalt mixture, thereby accurately and quantitatively evaluating the water stability of asphalt mixture in water environments with different pH values. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0028] Figure 1 This is a schematic diagram of the surface tension method test of the present invention;

[0029] Figure 2 This is a test principle diagram of the interfacial tension method of the present invention. DETAILED DESCRIPTION

[0030] The following examples are used to explain the implementation methods of the present application in detail, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0031] A method for testing surface energy parameters of an aqueous solution based on an interfacial tension method comprises the following steps:

[0032] S1. The platinum plate is cleaned with acetone, distilled water and acetone in sequence, and dried and removed by heating with an alcohol lamp. The pretreated platinum plate is then mounted on the balance fixture of the surface tension meter.

[0033] S2. Place a container containing 60 ml of the aqueous solution to be tested (it can be a glass container or an aluminum container, an aluminum container is selected here) on the lifting platform of the surface tension meter, immerse the temperature probe in the aqueous solution to be tested, and control the temperature of the aqueous solution to be tested to 20±0.1°C through the constant temperature system, so that the temperature of the aqueous solution to be tested is stable at 20±0.1°C for more than 10 minutes.

[0034] S3. Raise the lifting platform at a speed of 6mm / min until the bottom of the pre-treated platinum plate is about to touch the surface of the aqueous solution to be tested. Read the balance reading after it stabilizes. Continue to slowly lift it by 2mm. Read the balance reading after it stabilizes. Calculate the surface tension coefficient The average value of the test results for 5 consecutive times was taken as the surface tension coefficient of the contact surface between the aqueous solution to be tested and the air. The test results are shown in Table 1.

[0035] Table 1 Surface tension test results of aqueous solutions at different pH values

[0036]

[0037] When the pH of an aqueous solution at 7.0 is measured by the above method, its surface tension is 72.79 ergs / cm 2 , compared with the known theoretical value of 72.8ergs / cm 2 Compared with the above, the deviation is only 0.014%. Since the core of the surface tension method and the interfacial tension method is to use a platinum plate to test the reagent tension, the results obtained by using the surface / interfacial tension method to test the reagent surface / interfacial tension are reliable. It should be noted that since the three surface energy parameters and surface tension of the neutral aqueous solution with pH = 7.0 are known, the following text mainly determines the surface energy parameters of the aqueous solution with two pH values ​​of pH = 3.0 and pH = 11.0.

[0038] S4, repeat steps S1-S2, lift the lifting platform at a speed of 6 mm / min until the bottom of the pretreated platinum plate is about to touch the liquid surface of the two pH value test aqueous solutions, and read the balance reading after it stabilizes;

[0039] Slowly inject n-hexane into the container in step S4, and let it stand until the n-hexane and the two pH value tested aqueous solutions form a stable interface, then continue to slowly lift the lifting platform until the n-hexane completely immerses the platinum plate. After stabilization, read the balance reading, and combine the balance reading read in step S4 to calculate the interfacial tension coefficient γ WL(1) ;

[0040] Similarly, toluene is injected into the container in step S4 and allowed to stand until a stable interface is formed between the toluene and the two pH value tested aqueous solutions. The lifting platform is then slowly raised until the toluene completely immerses the platinum plate. After stabilization, the balance reading is read. Combined with the balance reading read in step S4, the interfacial tension coefficient γ is calculated. WL(2) .

[0041] The average value of the test results for five consecutive times was taken as the interfacial tension coefficient between the aqueous solution at two pH values ​​and the organic reagent. The test results are shown in Table 3.

[0042] Table 2 Basic performance indicators of organic reagents

[0043]

[0044] In the above table, γ LW , γ + , γ - , γ AB , γ are the non-polar component, polar acid component, polar base component, polar acid-base component and surface tension of the surface energy of the organic reagent, respectively.

[0045] Table 3 Interfacial tension test results of aqueous solution and organic reagent at two pH values

[0046] pH value of aqueous solution pH=3.0 pH=11.0 <![CDATA[Interfacial tension γ with n-hexane WL(2) , ergs / cm 2 > 36.98 41.89 <![CDATA[Interfacial tension γ with toluene WL(2) , ergs / cm 2 > 22.72 21.97

[0047] S5. γ WL(1) , γ WL(2) , surface energy parameters of n-hexane and And the surface energy parameters of toluene and Substituting into the GvOC equation,

[0048] The GvOC equation is:

[0049]

[0050] Solve to obtain the three basic components of the surface energy of the two pH values ​​of the aqueous solution to be tested and

[0051] Based on the above test data, the surface energy parameters of the aqueous solutions with two pH values ​​were calculated. The specific results are shown in Table 4.

[0052] Table 4 Surface energy parameters of aqueous solutions at two pH values

[0053]

[0054] In the above table, They are the non-polar component, polar acid component, polar alkaline component, polar acid-base component and surface tension of the surface energy of aqueous solutions with different pH values.

[0055] It can be seen from the table above that changes in acidity and alkalinity will cause changes in the distribution of surface energy parameters of aqueous solutions. Specifically:

[0056] 1) Compared with the neutral aqueous solution (pH = 7.0), the surface tension of the acidic aqueous solution with pH = 3.0 is slightly increased, and the surface tension of the alkaline aqueous solution with pH = 11.0 is slightly decreased;

[0057] 2) Compared with neutral aqueous solution, the non-polar component of the surface energy of acidic and alkaline aqueous solution showed an increasing trend, while the polar component showed a decreasing trend. The distribution of polar acid and alkaline components of acidic and alkaline aqueous solutions showed opposite trends, which is consistent with the trend of surface energy component changes of acidic and alkaline solutions obtained in the literature "Evaluation of the Effect of Dust and Soot on Runoff Acidity and Moisture Sensitivity of Asphalt Mixtures Using Thermodynamic and Mechanical Methods. Journal of Materials in Civil Engineering, 2020, 32(11): 04020313". This phenomenon may be due to the presence of abundant H in acidic and alkaline solutions. + OH - Ions break the polarity balance of neutral aqueous solution, causing the surface energy components of the aqueous solution to show different change patterns.

[0058] The above method can be used to accurately test the surface energy parameters of aqueous solutions with different pH values; on this basis, combined with the surface energy parameters of asphalt and aggregate, the adhesion energy between asphalt and aggregate under dry conditions can be calculated by the following formula.

[0059]

[0060] The following formula is then used to calculate the adhesion energy between asphalt and aggregate in water environments with different pH values.

[0061]

[0062] This is done to explore the specific effects of pH value on the surface energy parameters of water and the binding energy of asphalt mixtures, thereby accurately and quantitatively evaluating the water stability of asphalt mixtures in water environments with different pH values.

[0063] Asphalt-aggregate adhesion energy ΔG under dry conditions a(AS) The larger the absolute value, the better the adhesion between the two materials. When water exists at the interface between asphalt and aggregate, the adhesion energy of the three-phase materials ΔG a(AWS) The larger the absolute value, the more serious the damage to the asphalt-aggregate adhesion. The ratio of the two can be calculated by the following formula as an evaluation index of the water stability of asphalt mixture. The larger the ER value, the better the water stability of the asphalt mixture.

[0064]

[0065] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for testing surface energy parameters of aqueous solutions based on surface interfacial tension method, characterized in that: The following steps are involved: S1. Install the pretreated platinum plate on the balance fixture of the surface tension meter; S2. Place the container containing the aqueous solution to be tested on the lifting platform of the surface tension meter, immerse the temperature probe in the aqueous solution to be tested, and control the temperature of the aqueous solution to be tested to the test set temperature through the constant temperature system; S3. When the temperature of the aqueous solution to be tested is constant at the test temperature, lift the lifting platform until the surface of the aqueous solution to be tested is about to touch the bottom of the pre-treated platinum plate. Read the balance reading after it stabilizes. Continue to slowly lift it 2mm. Read the balance reading after it stabilizes. Calculate the surface tension coefficient S4, repeat steps S1-S2, lift the lifting platform until the bottom of the pre-treated platinum plate is about to touch the surface of the aqueous solution to be tested, and read the balance reading after it stabilizes; S5. Inject the organic reagent into the container in step S4, and let it stand until the organic reagent and the aqueous solution to be tested form a stable interface. Then continue to slowly lift the lifting platform until the organic reagent completely immerses the platinum plate. After stabilization, read the balance reading. Combined with the balance reading read in step S4, calculate the interfacial tension coefficient γ WL ; There are two kinds of organic reagents, both of which are used alone. The interfacial tension coefficient obtained by using the first organic reagent is recorded as γ WL(1) ; Using the second organic reagent, the interfacial tension coefficient is recorded as γ WL(2) ; S6. γ WL(1) , γ WL(2) , and three known surface energy parameters of the two organic reagents and and Substituting into the equations based on the GvOC model, the three basic parameters of the surface energy of the aqueous solution to be tested are obtained: and 2. The method for testing surface energy parameters of aqueous solution based on surface interfacial tension method according to claim 1, characterized in that: In step S1, the pretreated platinum plate is prepared by sequentially washing the platinum plate with acetone, distilled water, and acetone, and then drying the plate.

3. The method for testing surface energy parameters of aqueous solution based on surface interfacial tension method according to claim 1, characterized in that: In step S2, the pH of the aqueous solution to be tested is 3.0-11.

0.

4. The method for testing surface energy parameters of aqueous solution based on surface interfacial tension method according to claim 1, characterized in that: In step S2, the aqueous solution to be tested is 60 ml; the temperature of the aqueous solution to be tested is controlled to be 20±0.1°C, and the temperature stabilization time should be no less than 10 minutes.

5. The method for testing surface energy parameters of aqueous solution based on surface tension method according to claim 1, characterized in that: In step S3, the surface tension coefficient of the aqueous solution to be tested is The calculation principle is to use the property that the pretreated platinum plate can completely wet the aqueous solution, record the change in buoyancy of the pretreated platinum plate in the air and when immersed in the aqueous solution to be tested, and calculate it.

6. The method for testing surface energy parameters of aqueous solution based on surface interfacial tension method according to claim 1, characterized in that: In step S5, the interfacial tension coefficient γ of the contact interface between the aqueous solution to be tested and the organic reagent is WL The calculation principle is to use the property that the pretreated platinum plate can completely wet the aqueous solution, and to calculate it through the difference in force on the balance when the pretreated platinum plate enters the interface between two incompatible reagents.

7. The method for testing surface energy parameters of aqueous solution based on surface interfacial tension method according to claim 1, characterized in that: In step S5, the organic reagent is a water-insoluble organic reagent with a density less than that of water and known surface energy parameters, which includes n-hexane and toluene.

8. The method for testing surface energy parameters of aqueous solution based on surface interfacial tension method according to claim 1, characterized in that: In steps S3 and S5, the surface tension coefficient Interfacial tension coefficient γ WL(1) and γ WL(2) All the results are obtained by taking the average value after multiple tests.

9. The method for testing surface energy parameters of aqueous solution based on surface interfacial tension method according to claim 1, characterized in that: In step S6, the and The surface energy non-polar component, polar acid component and polar base component of the first organic reagent; and are the non-polar component, polar acid component and polar base component of the surface energy of the second organic reagent; and It is the non-polar component, polar acid component and polar base component of the surface energy of the aqueous solution to be tested.

10. The method for testing surface energy parameters of aqueous solution based on surface interfacial tension method according to claim 1, characterized in that: In step S6, the equation group based on the GvOC model is:

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