A method for testing surface energy parameters of aqueous solution based on interfacial tension method

Abstract

The present application relates to the technical field of road engineering, in particular to a water solution surface energy parameter testing method based on the surface interfacial tension method, comprising: first, surface tension testing is performed on the water solution to be tested to obtain the surface tension coefficient of the water solution to be tested; then, two kinds of organic reagents are selected, the two kinds of organic reagents are added into two portions of the water solution to be tested respectively, and the two portions are fully placed to form two different organic reagent-water solution contact interfaces; the interface tension of the two interfaces is tested respectively to obtain the interface tension coefficients of the water solution to be tested and the two kinds of organic reagents; finally, the surface tension coefficient, the two interface tension coefficients and the known surface energy parameters of the two kinds of organic reagents are substituted into the equation set based on the GvOC model to solve and determine the surface energy parameters of the water solution to be tested. The present application can accurately test the surface energy parameters of water solutions with different pH values, so as to accurately quantify and evaluate the water stability of asphalt mixtures under different pH value water environments.

Description

Technical Field

[0001] This invention relates to the field of road engineering technology, specifically to a method for testing the surface energy parameters of aqueous solutions based on interfacial tension. Background Technology

[0002] Under actual service conditions, asphalt pavements are exposed to the natural environment for extended periods and inevitably suffer from water erosion. Furthermore, the pH value of the aquatic environment in which asphalt mixtures are located is not always constant at 7.0. Acidic and alkaline water environments can undergo physicochemical reactions 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 pH=7.0 cannot objectively and accurately reflect the degree of water damage to asphalt mixtures. Moreover, since a water stability model for asphalt mixtures that considers the acidity or alkalinity of the aquatic environment has not yet been developed, existing experimental testing methods cannot accurately quantify the water stability of asphalt mixtures under actual service conditions.

[0003] Surface energy theory posits that the change in Gibbs free energy of a solid-liquid two-phase material at contact reflects the adhesion characteristics of the solid-liquid interface, which can be calculated using the material's surface energy parameters. With the continuous development of surface energy theory, it has been widely applied to quantitatively evaluate the water stability of asphalt mixtures. However, most studies only examine the water stability of asphalt mixtures in neutral aqueous environments. Therefore, there is an urgent need for a reasonable and reliable surface energy testing method to accurately determine the surface energy parameters of aqueous solutions with different pH values, thereby quantitatively evaluating the impact of pH on the water stability of asphalt mixtures. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for testing the surface energy parameters of aqueous solutions based on interfacial tension. This method can accurately test the surface energy parameters of aqueous solutions at different pH values, thereby accurately quantifying and evaluating the water stability of asphalt mixtures under different pH water environments.

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

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

[0007] 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 through the constant temperature system.

[0008] S3. When the temperature of the aqueous solution to be tested is constant at the test temperature, raise the lifting platform until the surface of the aqueous solution is about to contact the bottom of the pretreated platinum plate. After stabilization, read the balance reading. Continue to slowly raise the platform by 2 mm, and after stabilization, read the balance reading again. Calculate the surface tension coefficient. ;

[0009] S4. Repeat steps S1-S2, raise the lifting platform until the bottom of the pretreated platinum plate is about to touch the surface of the aqueous solution to be tested, and read the balance reading after stabilization.

[0010] S5. Inject the organic reagent into the container from step S4, and let it stand until a stable interface is formed between the organic reagent and the aqueous solution to be tested. Then, continue to slowly raise the lifting platform until the organic solvent completely immerses the platinum plate. After stabilization, read the balance reading. Combine this reading with the balance reading from step S4 to calculate the interfacial tension coefficient. ;

[0011] There are two types of organic reagents, both used alone; the interfacial tension coefficient obtained using the first organic reagent is denoted as... Using the second organic reagent, the interfacial tension coefficient is denoted as... ;

[0012] S6, will , , and the known surface energy parameters of the two organic reagents. , and , , and Substituting the equations into the system based on the Good-van Oss-Chaudhury (GvOC) model, the three fundamental components of the surface energy of the aqueous solution to be measured are obtained. , and .

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

[0014] Preferably, in step S2, the pH of the aqueous solution to be tested is 3.0 to 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 at 20 ± 0.1 °C, and the temperature stabilization time should not be less than 10 min.

[0016] Preferably, in step S3, the surface tension coefficient of the aqueous solution to be tested... The calculation principle utilizes the property that a pretreated platinum plate can completely wet an aqueous solution. Before immersion in the aqueous solution, the balance reading is... After being immersed in the aqueous solution, the balance reading is... Record the difference in the balance readings. The surface tension coefficient of the aqueous solution is calculated using the following formula, where... This represents the perimeter of the surface of the platinum plate cut off by the aqueous solution. This indicates the volume of the platinum plate immersed in the aqueous solution. This indicates the density of the aqueous solution. represents air density, and g represents gravitational acceleration.

[0017]

[0018] Preferably, in step S5, the interfacial tension coefficient at the interface between the aqueous solution to be tested and the organic reagent is... The calculation principle utilizes the property that the pretreated platinum plate can be completely wetted. Before the platinum plate is immersed in the aqueous solution, the balance reading is... After being immersed in the aqueous solution, the balance reading is... Record the difference in the balance readings. The interfacial tension coefficient between the aqueous solution and the organic reagent is calculated using the following formula, where... This represents the perimeter of the surface of the platinum plate intercepted at the interface between the aqueous solution and the organic reagent. Indicates the volume of the platinum plate. This indicates the volume of the platinum plate immersed in the aqueous solution. This indicates the density of the aqueous solution. Indicates the density of organic reagents, represents air density, and g represents gravitational acceleration.

[0019]

[0020] Preferably, in step S5, the organic reagent is a non-water-soluble organic reagent with a density less than that of water, including n-hexane and toluene.

[0021] Preferably, in steps S3 and S5, the surface tension coefficient interfacial tension coefficient and All results were obtained by taking the average value after multiple tests.

[0022] Preferably, in step S6, the , and The surface energy of the first organic reagent comprises the nonpolar component, the polar acid component, and the polar base component; , and It consists of the nonpolar component, polar acid component, and polar base component of the surface energy of the second type of organic reagent; , and It represents the nonpolar 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 system of equations based on the GvOC model is as follows:

[0024] .

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

[0026] This 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. Based on this, combined with the surface energy parameters of asphalt and aggregate, the adhesion binding energy of asphalt-aggregate under different pH water environments is calculated. This allows for the exploration of the influence of pH value on the surface energy parameters of water and on the binding energy of asphalt mixtures, thereby accurately quantifying and evaluating the water stability of asphalt mixtures under different pH water environments. Attached Figure Description

[0027] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0028] Figure 1 This is a schematic diagram illustrating the surface tension method testing principle of this invention.

[0029] Figure 2 This is a schematic diagram illustrating the interfacial tension method of this invention. Detailed Implementation

[0030] The following embodiments are provided to illustrate the implementation of this application in detail, so that the process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

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

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

[0033] S2. Place a container (which can be a glass container or an aluminum container, but an aluminum container is selected here) containing 60ml of 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 at 20±0.1℃ through the constant temperature system, so that the temperature of the aqueous solution to be tested is stable at 20±0.1℃ for more than 10 minutes.

[0034] S3. Raise the lifting platform at a speed of 6 mm / min until the bottom of the pretreated platinum plate is about to touch the surface of the aqueous solution to be tested. After stabilization, read the balance reading. Continue to slowly raise the platform by 2 mm, and after stabilization, read the balance reading again. Calculate the surface tension coefficient. The average value of five consecutive test results was taken as the surface tension coefficient of the surface of the aqueous solution in contact with 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 surface tension of an aqueous solution with pH=7.0 was measured using the above method, it was 72.79 ergs / cm. 2 =Compared with the known theoretical value of 72.8 ergs / cm 2 In comparison, the deviation was only 0.014%. Since both the surface tension method and the interfacial tension method rely on platinum plates for reagent tension testing, the results obtained using the surface / interfacial tension method are reliable. It should be noted that since the three surface energy parameters and surface tension of a neutral aqueous solution with pH=7.0 are known, the following discussion will primarily focus on determining the surface energy parameters of aqueous solutions with pH=3.0 and pH=11.0.

[0038] S4. Repeat steps S1-S2, raising the lifting platform at a speed of 6 mm / min until the bottom of the pretreated platinum plate is about to contact the surface of the two pH-tested aqueous solutions. After stabilization, read the balance reading.

[0039] Hexane is slowly injected into the container from step S4, and allowed to stand until a stable interface is formed between the hexane and the two pH-testing aqueous solutions. The platform is then slowly raised until the hexane completely submerges the platinum plate. After stabilization, the balance reading is recorded. Combined with the balance reading from step S4, the interfacial tension coefficient is calculated. ;

[0040] Similarly, toluene is injected into the container from step S4 and allowed to stand until a stable interface is formed between the toluene and the two pH-testing aqueous solutions. The lifting platform is then slowly raised until the toluene completely submerges the platinum plate. After stabilization, the balance reading is recorded. Combined with the balance reading from step S4, the interfacial tension coefficient is calculated. .

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

[0042] Table 2 Basic performance indicators of organic reagents

[0043]

[0044] In the above table, , , , , These are the nonpolar 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. Results of interfacial tension tests between aqueous solutions and organic reagents at two different pH values.

[0046]

[0047] S5, will , , 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 as follows:

[0049]

[0050] The three fundamental components of the surface energy of the aqueous solutions at the two pH values ​​were obtained by solving the problem. , and .

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

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

[0053]

[0054] In the above table, , , , , These represent the surface energy nonpolar component, polar acid component, polar base component, polar acid-base component, and surface tension of aqueous solutions with different pH values.

[0055] As can be seen from the table above, changes in acidity or alkalinity lead to changes in the surface energy parameter distribution of the aqueous solution. Specifically:

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

[0057] 2) Compared with neutral aqueous solutions, the nonpolar components of surface energy in acidic and alkaline aqueous solutions both show an increasing trend, while the polar components both show a decreasing trend. Furthermore, the distribution of polar acid and alkaline components in acidic and alkaline aqueous solutions exhibits opposite trends. This is consistent with the trend of surface energy component changes in 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 abundance of H+ in acidic and alkaline solutions. + OH - Ions disrupt the polarity balance of neutral aqueous solutions, resulting in different variation patterns in the surface energy components of the aqueous solution.

[0058] The above method can accurately test the surface energy parameters of aqueous solutions with different pH values; based on this, 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] Then, the adhesion bonding energy between asphalt and aggregate under different pH water environments is calculated using the following formula.

[0061]

[0062] This study aims to investigate the specific effects of pH value on the surface energy parameters of water and on the binding energy of asphalt mixtures, thereby accurately quantifying and evaluating the water stability of asphalt mixtures under different pH water environments.

[0063] Asphalt-aggregate adhesion energy under dry conditions The larger the absolute value, the better the adhesion between the two materials. However, when water is present at the interface between asphalt and aggregate, the adhesion bonding energy of the three-phase materials... The larger the absolute value, the more severe the damage to the asphalt-aggregate adhesion. The ratio of the two can be calculated using the following formula and used as an evaluation index for the water stability of asphalt mixtures. The larger the ER value, the better the water stability of the asphalt mixture.

[0064]

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

Claims

1. A method for testing the surface energy parameter of an aqueous solution based on the interfacial tension method, characterized by, The method comprises the following steps: S1, mounting a pretreated platinum plate on a balance clamp of a surface tension instrument; S2, placing a container containing a water solution to be tested on a lifting platform of the surface tension instrument, immersing a temperature probe into the water solution to be tested, and controlling the temperature of the water solution to be tested to a set temperature by a constant temperature system; S3, when the temperature of the water solution to be measured is constant at the test temperature, lift the lifting platform to the water solution to be measured to be about to contact the bottom of the pretreated platinum plate, read the balance reading after stabilization, continue to slowly lift 2mm, read the balance reading after stabilization, and calculate the surface tension coefficient ; S4, repeating steps S1-S2, lifting the lifting platform to the bottom of the pretreated platinum plate to contact the surface of the water solution to be tested, and reading the balance reading after stabilization; S5, injecting organic reagent into the container in step S4, standing until the organic reagent and the water solution to be tested form a stable interface, then continuing to slowly lift the lifting platform until the organic reagent completely submerges the platinum-gold plate, reading the balance reading after stabilization, calculating the interfacial tension coefficient in combination with the balance reading read in step S4 ; Among them, the organic reagents have two in common, both of which are used alone; the interfacial tension coefficient obtained by using the first organic reagent is denoted as ; the interfacial tension coefficient obtained by using the second organic reagent is denoted as ; S6, will , , and three known surface energy parameters of the two organic reagents. , and , , and Substituting the equations into the system based on the Good-van Oss-Chaudhury model, the three fundamental parameters of the surface energy of the aqueous solution to be measured are obtained. , and ; In step S6, the , and are the non-polar component, the polar acid component and the polar base component of the surface energy of the first organic reagent; the , and are the non-polar component, the polar acid component and the polar base component of the surface energy of the second organic reagent; , and are the non-polar component, the polar acid component and the polar base component of the surface energy of the aqueous solution to be tested.

2. The method for testing the surface energy parameter of aqueous solution based on the interfacial tension method according to claim 1, characterized in that, In step S1, the pretreated platinum plate is prepared by sequentially cleaning the platinum plate with acetone, distilled water, and acetone, and then drying.

3. The method according to claim 1, wherein the method is characterized by, In step S2, the pH of the water solution to be tested is 3.0-11.

0.

4. The method according to claim 1, wherein the method is characterized by, In step S2, the water solution to be tested is 60ml; the temperature of the water solution to be tested is controlled to be 20±0.1℃, and the temperature stabilization time should be no less than 10min.

5. The method according to claim 1, wherein the method is characterized by, In step S3, the surface tension coefficient of the water solution to be measured is calculated The calculation principle is that the pre-processed platinum plate can be completely wetted by the water solution, and the change in the buoyancy of the pre-processed platinum plate in air and immersed in the water solution to be measured is recorded to obtain the calculation result.

6. The method according to claim 1, wherein the method is characterized by, In step S5, the interfacial tension coefficient of the interface between the water solution to be measured and the organic reagent The calculation principle is that the pre-processed platinum plate can completely wet the water solution, and the interfacial tension coefficient is calculated by the difference of the force received by the balance when the pre-processed platinum plate enters the interface between the two incompatible reagents.

7. The method according to claim 1, wherein the method is characterized by, In step S5, the organic reagent is a non-water-soluble organic reagent with a density less than water and known surface energy parameters, which includes n-hexane and toluene.

8. The method according to claim 1, wherein the method is characterized by, In steps S3 and S5, the surface tension coefficient , the interfacial tension coefficient , and are obtained by averaging the values from multiple tests.

9. The method according to claim 1, wherein the method is characterized by, In step S6, the equation set based on the Good-van Oss-Chaudhury model is: 。

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