Method for positioning surface nanobubbles and testing bridging effect of surface nanobubbles

Abstract

The invention relates to a method for positioning surface nanobubbles and testing the bridging effect of the surface nanobubbles, belongs to the technical field of interaction between colloid interfaces, and solves the problems that the surface nanobubbles cannot be positioned and the bridging effect of the surface nanobubbles cannot be determined in the prior art. Comprising the steps that colloidal particles are cleaned, and the surfaces of the colloidal particles reach the nanoscale cleaning degree; carrying out surface modification on the colloidal particles to obtain hydrophobic colloidal particles; the method comprises the following steps: adhering an adhesive to a probe without a needle tip, adhering a single hydrophobic colloidal particle to the probe adhered with the adhesive, and performing ultraviolet irradiation to obtain a colloidal probe; fixing a colloid probe on a scanning head of an atomic force microscope, and scanning the morphology of the surface nanobubbles by using the colloid probe so as to position the surface nanobubbles; and testing the interaction force between the colloidal particles at the surface nanobubbles by using the colloidal probe so as to determine the nanobubble bridging effect. According to the method, the surface nanobubbles can be accurately positioned, and the bridging effect of the surface nanobubbles can be tested.

Description

Technical Field

[0001] The invention relates to the technical field of inter-colloid interface interaction, and in particular to a method for surface nanobubble positioning and surface nanobubble bridging effect testing. Background Art

[0002] The hydrophobic interaction between colloidal particles in aqueous solution, also known as hydrophobic attraction, has attracted much attention in the fields of biology, medicine, and industrial production. Many applications rely on the existence of hydrophobic attraction, such as the attraction between bubbles and hydrophobic particles in froth flotation and the interaction between hydrophobic particles in hydrophobic agglomeration.

[0003] Surface nanobubbles are extremely small bubbles formed at the solid-liquid interface. Their size is generally less than 1 micron, and the liquid contact angle is between 120° and 175°. Compared with macroscopic large bubbles and micron bubbles, surface nanobubbles have unique physical and chemical properties such as large specific surface area, large solid-gas interface contact angle, and long life. In recent years, the application of surface nanobubbles in wastewater treatment, aquaculture oxygenation, ship drag reduction, and ore flotation has begun to attract widespread attention.

[0004] Surface nanobubbles selectively attach to hydrophobic surfaces and induce a significant "jump-in" attraction in the microscopic interactions between hydrophobic particles through the bridging effect. This long-range force is called "nanobubble bridging capillary force". Existing technologies cannot locate nanobubbles or clearly test the bridging effect of surface nanobubbles between particles. Summary of the invention

[0005] In view of the above analysis, the embodiments of the present invention are intended to provide a method for locating surface nanobubbles and testing the bridging effect of surface nanobubbles, so as to solve at least one of the following problems existing in the prior art: (1) the surface nanobubbles cannot be located; (2) the bridging effect of surface nanobubbles between particles cannot be clearly tested.

[0006] On the one hand, an embodiment of the present invention provides a method for surface nanobubble positioning and surface nanobubble bridging effect testing, the method comprising:

[0007] Step 1: Clean the colloidal particles to make their surface clean to nanoscale level;

[0008] Step 2: modifying the surface of the colloidal particles to obtain hydrophobic colloidal particles;

[0009] Step 3: sticking the probe without a needle tip onto the adhesive, and then sticking the probe with the adhesive onto a single hydrophobic colloidal particle, and irradiating with ultraviolet light to obtain a colloidal probe;

[0010] Step 4: fixing the colloidal probe on the scanning head of an atomic force microscope, and using the colloidal probe to scan the morphology of nanobubbles on the surface of the sample to be tested, thereby locating the nanobubbles on the surface;

[0011] Step 5: Using the colloidal probe to test the interaction force between colloidal particles at locations with surface nanobubbles and the interaction force between colloidal particles at locations without surface nanobubbles, and obtain the hydrophobic attraction and hydrophobic interaction range between colloidal particles at corresponding locations.

[0012] Step 6: Analyze the relationship between the hydrophobic attraction and hydrophobic interaction between the colloid particles when there are surface nanobubbles and the hydrophobic attraction and hydrophobic interaction between the colloid particles when there are no surface nanobubbles, and determine the bridging effect of the surface nanobubbles between the colloid particles.

[0013] Preferably, the colloidal particles have a particle size of 3-5 μm.

[0014] Preferably, the step 1 comprises:

[0015] Step 101: Clean the beaker with piranha solution;

[0016] Step 102: placing the colloidal particles in a cleaned beaker;

[0017] Step 103: Add acetone to the beaker and use ultrasonic cleaning to remove contaminants on the surface of the colloidal particles; let it stand and pour out the supernatant;

[0018] Step 104: Repeat step 103 at least twice;

[0019] Step 105: Seal the beaker with plastic wrap, poke a plurality of holes in the plastic wrap, and place the plastic wrap in a vacuum drying oven to dry;

[0020] Step 106: using oxygen plasma to remove residual organic pollutants on the surface of the dried colloidal particles, thereby obtaining colloidal particles with a surface cleanliness level of nanometers.

[0021] Preferably, in step 2, the surface modification of the colloidal particles comprises: immersing the colloidal particles in an OTS-toluene solution for modification.

[0022] Preferably, an optical microscope is used in combination with an atomic force microscope to achieve sequential adhesion of the adhesive and the single hydrophobic colloidal particle by a needle-free probe.

[0023] Preferably, in step 103, the ultrasonic cleaning time is 1-3 minutes.

[0024] Preferably, in step 103, the standing time is 1-5 minutes.

[0025] Preferably, in step 2, in the OTS-toluene solution, the volume ratio of OTS to toluene is 2.5:1000-2.5:100.

[0026] Preferably, in step 2, the immersion time of the colloidal particles in the OTS-toluene solution is 10-15 min.

[0027] Preferably, in step 3, the ultraviolet light irradiation time is 3-10 min.

[0028] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0029] 1. The method of the present invention can accurately locate surface nanobubbles, and first accurately locate the surface nanobubbles to obtain the nanobubble outline, and then test the particle interaction force with or without surface nanobubbles, determine the bridging effect of surface nanobubbles between colloidal particles, and obtain the influence of surface nanobubbles on the hydrophobic interaction between colloidal particles. It can clarify the strengthening effect of surface nanobubbles on the hydrophobic attraction and hydrophobic interaction process between colloidal particles through the bridging effect, which has important theoretical guiding significance for fine particle agglomeration and particle flotation.

[0030] 2 The method of the present invention is simple and applicable to various types of atomic force microscopes. By strictly following the steps, the colloidal probe can be prepared, thus making the method highly operable.

[0031] 3. The present invention cleans the colloidal particles with a particle size of 3-5 μm, so that the surface of the colloidal particles reaches a nano-level cleanliness level, thereby avoiding the accuracy of subsequent surface nano-bubble bridging force detection being affected by impurities on the surface of the colloidal particles.

[0032] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0034] Figure 1 It is a flow chart of the method for surface nanobubble positioning and surface nanobubble bridging effect testing of the present invention;

[0035] Figure 2 This is a surface nanobubble morphology image scanned by an atomic force microscope colloidal probe in Example 1;

[0036] Figure 3 It is a force spectrum of adhesion between colloidal particles with and without surface nanobubbles tested by the atomic force microscope colloidal probe of Example 1;

[0037] Figure 4 is the interaction force diagram between colloidal particles in the absence of surface nanobubbles in Example 1;

[0038] Figure 5 The force diagram of the interaction between colloidal particles in the presence of surface nanobubbles in Example 1;

[0039] Figure 6 This is a force spectrum diagram of the colloidal particles with and without surface nanobubbles tested by the atomic force microscope colloidal probe of Comparative Example 1.

[0040] Reference numerals:

[0041] A-beaker; B-ultrasonic cleaning machine; C-plastic wrap; D-oxygen plasma; E-atomic force microscope; F-optical microscope; G-ultraviolet light; H-colloidal probe. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0043] The present invention provides a method for surface nanobubble positioning and surface nanobubble bridging effect testing, such as Figure 1 As shown, the method includes:

[0044] Step 1: Clean the colloidal particles to make their surface clean to nanoscale level;

[0045] Step 2: Surface modification of the colloidal particles to obtain hydrophobic colloidal particles;

[0046] Step 3: The probe without a needle tip is attached to the adhesive, and then the probe attached to the adhesive is attached to a single hydrophobic colloidal particle, and after irradiation with ultraviolet light G, a colloidal probe H is obtained;

[0047] Step 4: Fix the colloidal probe H on the scanning head of the atomic force microscope E (the probe is millimeter-scale, clamped with a probe clamp, and then fixed on the scanning head of the atomic force microscope), and use the colloidal probe H to scan the nanobubble morphology on the surface of the sample to be tested, so as to locate the surface nanobubbles;

[0048] Step 5: using the colloidal probe to test the interaction force between colloidal particles at locations with surface nanobubbles and the interaction force between colloidal particles at locations without surface nanobubbles, and obtaining the hydrophobic attraction and hydrophobic interaction range between colloidal particles at corresponding locations;

[0049] Step 6: Analyze the relationship between the hydrophobic attraction and hydrophobic interaction between the colloid particles when there are surface nanobubbles and the hydrophobic attraction and hydrophobic interaction between the colloid particles when there are no surface nanobubbles, so as to determine the bridging effect of the surface nanobubbles between the colloid particles.

[0050] Compared with the prior art, the method of the present invention can accurately locate surface nanobubbles, and by first accurately locating the surface nanobubbles to obtain the nanobubble outline, and then testing the interaction force between particles with or without surface nanobubbles, the bridging effect of surface nanobubbles between colloidal particles is determined, and the influence of surface nanobubbles on the hydrophobic interaction between colloidal particles is obtained. The strengthening effect of surface nanobubbles on the hydrophobic attraction and hydrophobic interaction process between colloidal particles through the bridging effect can be clarified, which has important theoretical guiding significance for fine particle agglomeration and particle flotation.

[0051] Exemplarily, the sample to be tested is highly oriented pyrolytic graphite flakes, mica, or pyrite.

[0052] For example, the colloidal particles have a particle size of 3-5 μm, such as 3 μm, 4 μm, and 5 μm. If the particle size of the colloidal particles is too large, the nanobubbles cannot be scanned; if the particle size is too small, the measured interaction force cannot be considered as the interaction force between the colloidal particles, but may be the interaction force between the nanobubbles and the particles.

[0053] In the present invention, the purpose of cleaning the colloidal particles in step 1 is to make the surface of the colloidal particles reach a nanometer-level cleanliness, thereby avoiding the accuracy of subsequent nanobubble bridging force detection affected by impurities on the surface of the colloidal particles. The nanometer-level cleanliness refers to the surface roughness being at the nanometer level.

[0054] Exemplarily, the particle surface scanning range is 500nm*500nm, and the corresponding colloidal particle apparent roughness arithmetic average Ra is 0.6-0.8nm.

[0055] In order to make the surface of the colloidal particles reach the nano-level cleanliness level, the step 1 comprises:

[0056] Step 101: Clean beaker A with piranha solution;

[0057] Step 102: placing the colloidal particles in the cleaned beaker A;

[0058] Step 103: Add acetone to the beaker and use ultrasonic cleaning to remove contaminants on the surface of the colloidal particles; let it stand and pour out the supernatant;

[0059] Step 104: Repeat step 103 at least twice;

[0060] Step 105: Seal the beaker A with a plastic wrap C, poke a plurality of holes in the plastic wrap C, and place the plastic wrap C in a vacuum drying oven to dry;

[0061] Step 106: using oxygen plasma D to remove residual organic pollutants on the surface of the dried colloidal particles, thereby obtaining colloidal particles with a nano-scale cleanliness level on the surface.

[0062] Illustratively, in step 101, the beaker A may be a 10 mL beaker.

[0063] Exemplarily, in step 102, the amount of colloidal particles is 10-20 mg, such as 12 mg, 14 mg, 16 mg, 18 mg, etc. Too much particle amount is not conducive to cleaning, but too little particle amount will remain in the beaker.

[0064] Illustratively, in step 103, the amount of acetone used is 3-5 mL, such as 3 mL, 4 mL, 5 mL, etc.

[0065] Exemplarily, in step 103, the ultrasonic cleaning time is 1-3 minutes, such as 1 minute, 2 minutes, 3 minutes, etc. If the ultrasonic cleaning time is too long, the particles will be broken, and if it is too short, the cleaning effect will not be achieved.

[0066] For example, in step 103, the standing time is 1-5 minutes, such as 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, etc. Since the particle size is very small, it is necessary to stand for a period of time to allow the particles to settle. The standing time is determined according to the particle concentration. If the time is too long, the test time will be increased, and if the time is too short, the particles cannot be fully settled.

[0067] Exemplarily, in step 103, the ultrasonic cleaning is performed using ultrasonic cleaning machine B.

[0068] Exemplarily, in step 105, the vacuum drying temperature is 35-60°C (e.g., 40°C, 45°C, 50°C, 55°C, etc.), the relative value of the vacuum drying pressure is -0.1MPa to -0.08MPa (e.g., -0.1MPa, -0.09MPa, -0.08MPa, etc.), and the vacuum drying time is 2-5h (e.g., 2.5h, 3h, 3.5h, 4h, 4.5h, etc.). If the temperature or pressure is too low and the drying time is too long, the probability of sample contamination will increase; if the temperature or pressure is too high, the particles may float out during the drying process.

[0069] For example, in step 2, the modification of the colloidal particles includes: soaking the colloidal particles in an OTS-toluene solution for modification, and washing the soaked colloidal particles. OTS stands for octadecyltrichlorosilane, which can react with hydroxyl groups on the surface of the particles. After the reaction, the carbon chain of OTS remains on the surface of the colloidal particles to make the particle surface hydrophobic; toluene is a solvent used to dilute OTS.

[0070] For example, in step 2, in the OTS-toluene solution, the volume ratio of OTS to toluene is 2.5:1000-2.5:100. For example, 2.5:900, 2.5:800, 2.5:700, 2.5:600, 2.5:500, 2.5:400, 2.5:300, 2.5:200, etc. If the OTS concentration is too low, the modification effect cannot be achieved; if the concentration is too high, more reagents will remain on the surface of the particles, which is not conducive to cleaning.

[0071] For example, in step 2, the immersion time of the colloidal particles in the OTS-toluene solution is 10-15 minutes, such as 11 minutes, 12 minutes, 13 minutes, 14 minutes, etc. If the immersion time is too short, the hydrophobic reaction cannot be fully carried out, but if the time is too long, OTS will react with water molecules in the air and become ineffective, and the reaction product is not conducive to cleaning.

[0072] Exemplarily, in step 3, an optical microscope F is used in conjunction with an atomic force microscope E to achieve a tip-free probe that sequentially picks up an adhesive and a single hydrophobic colloidal particle, specifically comprising: fixing the probe on the atomic force microscope E, inverting the optical microscope F, finding a single particle under observation of the optical microscope F, using the atomic force microscope E to control the tip-free probe to first pick up the adhesive, and then the probe with the adhesive picks up a single hydrophobic colloidal particle. The adhesive is used to stick a single hydrophobic colloidal particle to the tip-free probe. The present invention uses an optical microscope F in conjunction with an atomic force microscope E, so that the probe can accurately pick up an adhesive and small-diameter (3-5 μm) colloidal particles.

[0073] Specifically, in step 3, the adhesive is a UV-curable adhesive.

[0074] Exemplarily, the adhesive is at least one of NEA123L, NEA121, and LB3731.

[0075] In step 3, the purpose of the ultraviolet light irradiation is to cure the adhesive.

[0076] In order to fully cure the adhesive, in step 3, the ultraviolet light irradiation time is 3-10 minutes, for example, 3 minutes, 5 minutes, 7 minutes, 9 minutes, 10 minutes, etc.

[0077] Exemplarily, the intensity of the ultraviolet light is 50-60 Hz. If the intensity is too high, the hydrophobic particles will be oxidized, affecting the hydrophobicity of the surface.

[0078] It should be noted that the scanning in step 4 and step 5 of the present invention is performed within the same range of the sample, and the scanning range includes the area with surface nanobubbles and the area without surface nanobubbles.

[0079] Specifically, in step 4, the colloid probe H is used to scan the surface nanobubble morphology of the sample to be tested, including: using the colloid probe H to scan an area range of the sample to be tested, in which there must be areas with surface nanobubbles and areas without surface nanobubbles, the colloid probe H transmits the scanning signal to the atomic force microscope E, and after receiving the data, the atomic force microscope E can identify the surface nanobubble morphology and locate the surface nanobubbles according to the different substrate surfaces.

[0080] It should be noted that in step 5, the colloid probe is used to test the interaction force between the colloid particles at the location with surface nanobubbles and the interaction force between the colloid particles at the location without surface nanobubbles, and the hydrophobic attraction and hydrophobic interaction range between the colloid particles at the corresponding positions are obtained, including: the colloid probe H is still fixed on the atomic force microscope E, and the colloid probe H is used to scan in the same range as step 4, the colloid probe H transmits the scanning signal to the atomic force microscope E, and after receiving the data, the atomic force microscope E displays the scanning results of the forces at various locations within the range, including the interaction force results between the colloid particles at the location with surface nanobubbles and the interaction force between the colloid particles at the location without surface nanobubbles. As for the force result, since the surface nanobubbles in the area have been located in step 4, it is possible to determine whether there are nanobubbles at each point in the measured force curve; based on the interaction force between the colloid particles at the location where the surface nanobubbles are present, the hydrophobic attraction and hydrophobic range between the colloid particles at the location where the surface nanobubbles are present are obtained; based on the interaction force between the colloid particles at the location where the surface nanobubbles are not present, the hydrophobic attraction and hydrophobic range between the colloid particles at the location where the surface nanobubbles are not present are obtained; specifically, in the process of the colloid particles approaching the substrate, a negative value will be generated on the needle force curve between the two, and this negative value is the hydrophobic attraction between the two, and the position where the negative value begins to be generated is the range of action corresponding to the attraction.

[0081] Specifically, in step 6, the relationship between the hydrophobic attraction and hydrophobic action range between the colloid particles at the surface nanobubbles and the hydrophobic attraction and hydrophobic action range between the colloid particles when there are no surface nanobubbles is analyzed, so as to determine the bridging effect of the surface nanobubbles between the colloid particles. By analyzing the gravitational force and the corresponding action range on the needle force curve, the presence of nanobubbles will increase the gravitational force, and the nanobubble height is positively correlated with the action range. Therefore, if the hydrophobic attraction and hydrophobic action range between the colloid particles at the surface nanobubbles are greater than the hydrophobic attraction and hydrophobic action range between the colloid particles when there are no surface nanobubbles, it can be determined that the surface nanobubbles have a bridging effect between the colloid particles.

[0082] The method for testing the nanobubble positioning and nanobubble bridging effect of the present invention is further described below through specific examples.

[0083] Example 1

[0084] This embodiment provides a method for nanobubble positioning and nanobubble bridging effect testing, including:

[0085] Step 1: Clean the colloidal particles to make their surface clean at the nano level, including:

[0086] Step 101: Wash 10 mL beaker A with piranha solution;

[0087] Step 102: placing colloidal particles weighing 15 mg and having a particle size of 4 μm in a cleaned beaker A;

[0088] Step 103: Add 4 mL of acetone to the beaker and use an ultrasonic cleaner to remove contaminants on the surface of the colloidal particles; let stand for 3 minutes and pour out the supernatant;

[0089] Step 104: Repeat step 103 twice;

[0090] Step 105: Seal the beaker A with plastic wrap C, poke a plurality of holes in the plastic wrap C, and place it in a vacuum drying oven for drying; the vacuum drying temperature is 55° C., the relative value of the vacuum drying pressure is -0.09 MPa, and the vacuum drying time is 3 hours.

[0091] Step 106: using oxygen plasma D to remove residual organic pollutants on the surface of the dried colloidal particles, to obtain colloidal particles with a surface cleanliness level at the nanometer level (arithmetic mean roughness Ra is 0.7 nm).

[0092] Step 2: Soak the colloidal particles in an OTS-toluene solution for modification, the volume ratio of OTS to toluene is 2.5:800, the soaking time is 12 minutes, and the soaked colloidal particles are washed to obtain hydrophobic colloidal particles.

[0093] Step 3: Fix the tipless probe on the atomic force microscope E. Under the observation of the optical microscope F, use the atomic force microscope E to control the tipless probe to first stick to the adhesive, and then stick the probe with the adhesive to a single hydrophobic colloidal particle. After irradiation with ultraviolet light G for 3 minutes, the colloidal probe H is obtained.

[0094] Step 4: Fix the colloidal probe H on the scanning head of the atomic force microscope E, and use the colloidal probe H to scan a 15μm*15μm area of ​​the sample to be tested. The colloidal probe H transmits the scanning signal to the atomic force microscope E. After receiving the data, the atomic force microscope E can identify the morphology of nanobubbles according to the different substrate surfaces and locate the surface nanobubbles, such as Figure 2 shown.

[0095] Step 5: The colloid probe H is still fixed on the atomic force microscope E, and the colloid probe H is used to scan the same area as step 4. The colloid probe H transmits the scanning signal to the atomic force microscope E. After receiving the data, the atomic force microscope E displays the scanning results of the interaction force between the colloid particles at various locations within the range, including the interaction force results between the colloid particles at the location with surface nanobubbles and the interaction force results between the colloid particles at the location without surface nanobubbles, such as Figure 3 shown; according to Figure 3 The interaction force curve between colloidal particles without surface nanobubbles is obtained (such as Figure 4 ) and the interaction force curve between colloidal particles at the surface nanobubbles (as shown in Figure 5 shown), specifically, Figure 3 Each small square on the diagram is a set of needle insertion and withdrawal force curves. When analyzing the data, you can read the force curve of the corresponding position by clicking on the corresponding position in the AFM analysis software. Figure 4 It can be seen that there is almost no attraction between the colloidal particles in the needle-entry force curve without surface nanobubbles, and the maximum hydrophobic adhesion force in the needle-retraction force curve is only 1.7 nN; Figure 5 It can be seen that the distance at which the "jump-in" attraction between colloidal particles occurs at the surface nanobubbles is 60.1 nm, and the maximum hydrophobic attraction on the needle-entry force curve and the maximum hydrophobic adhesion force on the needle-retraction force curve between colloidal particles are 120.5 nN and 256.4 nN, respectively.

[0096] Step 6: The distance of the "jumping" attraction is the hydrophobic range, and the negative values ​​on the needle force curve and the needle force curve are the hydrophobic attraction between the colloid particles. From the data obtained in step 5, it can be seen that the hydrophobic attraction and hydrophobic range between the colloid particles in the presence of surface nanobubbles are greater than those in the absence of surface nanobubbles, thus confirming the existence of the bridging effect of surface nanobubbles between the colloid particles.

[0097] Example 2

[0098] This embodiment provides a method for nanobubble positioning and nanobubble bridging effect testing, including:

[0099] Step 1: Clean the colloidal particles to make their surface clean at the nano level, including:

[0100] Step 101: Wash 10 mL beaker A with piranha solution;

[0101] Step 102: placing colloidal particles weighing 10 mg and having a particle size of 3 μm in a cleaned beaker A;

[0102] Step 103: Add 3 mL of acetone to the beaker, and use an ultrasonic cleaner to remove contaminants on the surface of the colloidal particles for 1 min; let stand for 1 min, and discard the supernatant;

[0103] Step 104: Repeat step 103 at least twice;

[0104] Step 105: Seal the beaker A with plastic wrap C, poke a plurality of holes in the plastic wrap C, and place it in a vacuum drying oven for drying; the vacuum drying temperature is 40° C., the relative value of the vacuum drying pressure is -0.1 MPa, and the vacuum drying time is 2 h.

[0105] Step 106: using oxygen plasma D to remove residual organic pollutants on the surface of the dried colloidal particles, to obtain colloidal particles with a surface cleanliness level of nanometer level (the arithmetic mean value of roughness Ra is 0.6 nm).

[0106] Step 2: Soaking the colloidal particles in an OTS-toluene solution for modification, the volume ratio of OTS to toluene is 2.5:1000, the soaking time is 15 min, and the soaked colloidal particles are washed to obtain hydrophobic colloidal particles;

[0107] Step 3: fix the tipless probe on the atomic force microscope E, and under the observation of the optical microscope F, use the atomic force microscope E to control the tipless probe to first stick to the adhesive, and then stick the probe with the adhesive to a single hydrophobic colloidal particle, and after irradiation with ultraviolet light G for 5 minutes, obtain the colloidal probe H;

[0108] Step 4: Fix the colloidal probe H on the scanning head of the atomic force microscope E, and use the colloidal probe H to scan a 6μm*6μm area of ​​the sample to be tested. The colloidal probe H transmits the scanning signal to the atomic force microscope E. After receiving the data, the atomic force microscope E identifies the morphology of the nanobubbles and locates the surface nanobubbles.

[0109] Step 5: The colloid probe H is still fixed on the atomic force microscope E, and the colloid probe H is used to scan within the same area as step 4. The colloid probe H transmits the scanning signal to the atomic force microscope E. After receiving the data, the atomic force microscope E displays the scanning results of the interaction force between the colloid particles at various locations within the range, including the interaction force results between the colloid particles at the location with surface nanobubbles and the interaction force results between the colloid particles at the location without surface nanobubbles. According to the interaction force curve between the colloid particles at the location with surface nanobubbles and the interaction force curve between the colloid particles at the location without surface nanobubbles, the hydrophobic attraction and hydrophobic interaction range between the colloid particles at the location with surface nanobubbles and the location without surface nanobubbles are obtained.

[0110] Step 6: Compare the hydrophobic attraction and hydrophobic interaction between the colloid particles where there are surface nanobubbles with those where there are no surface nanobubbles. The hydrophobic attraction and hydrophobic interaction between the colloid particles where there are surface nanobubbles are greater than those where there are no surface nanobubbles, thereby confirming the existence of the bridging effect of the surface nanobubbles between the colloid particles.

[0111] Example 3

[0112] This embodiment provides a method for nanobubble positioning and nanobubble bridging effect testing, including:

[0113] Step 1: Clean the colloidal particles to make their surface clean at the nano level, including:

[0114] Step 101: Wash 10 mL beaker A with piranha solution;

[0115] Step 102: placing 20 mg of colloidal particles with a particle size of 5 μm in a cleaned beaker A;

[0116] Step 103: Add 5 mL of acetone to the beaker, and use an ultrasonic cleaner to remove contaminants on the surface of the colloidal particles for 3 minutes; let stand for 5 minutes, and discard the supernatant;

[0117] Step 104: Repeat step 103 at least twice;

[0118] Step 105: Seal the beaker A with plastic wrap C, poke a plurality of holes in the plastic wrap C, and place it in a vacuum drying oven for drying; the vacuum drying temperature is 60° C., the relative value of the vacuum drying pressure is -0.08 MPa, and the vacuum drying time is 5 hours.

[0119] Step 106: using oxygen plasma D to remove residual organic pollutants on the surface of the dried colloidal particles, to obtain colloidal particles with a surface cleanliness level of nanometer level (the arithmetic mean value Ra of the roughness is 0.8 nm).

[0120] Step 2: Soaking the colloidal particles in an OTS-toluene solution for modification, the volume ratio of OTS to toluene is 2.5:100, the soaking time is 10 min, and the soaked colloidal particles are washed to obtain hydrophobic colloidal particles;

[0121] Step 3: fix the tipless probe on the atomic force microscope E, and under the observation of the optical microscope F, use the atomic force microscope E to control the tipless probe to first stick to the adhesive, and then stick the probe with the adhesive to a single hydrophobic colloidal particle, and after irradiation with ultraviolet light G for 10 minutes, obtain the colloidal probe H;

[0122] Step 4: Fix the colloidal probe H on the scanning head of the atomic force microscope E, and use the colloidal probe H to scan a 10μm*10μm area of ​​the sample to be tested. The colloidal probe H transmits the scanning signal to the atomic force microscope E. After receiving the data, the atomic force microscope E locates the surface nanobubbles and identifies the morphology of the nanobubbles.

[0123] Step 5: The colloid probe H is still fixed on the atomic force microscope E, and the colloid probe H is used to scan within the same area as step 4. The colloid probe H transmits the scanning signal to the atomic force microscope E. After receiving the data, the atomic force microscope E displays the scanning results of the interaction force between the colloid particles at various locations within the range, including the interaction force results between the colloid particles at the location with surface nanobubbles and the interaction force results between the colloid particles at the location without surface nanobubbles. According to the interaction force curve between the colloid particles at the location with surface nanobubbles and the interaction force curve between the colloid particles at the location without surface nanobubbles, the hydrophobic attraction and hydrophobic interaction range between the colloid particles at the location with surface nanobubbles and the location without surface nanobubbles are obtained.

[0124] Step 6: Analyze the relationship between the hydrophobic attraction and hydrophobic interaction between the colloid particles in the presence of surface nanobubbles and the hydrophobic attraction and hydrophobic interaction between the colloid particles in the absence of surface nanobubbles. The hydrophobic attraction and hydrophobic interaction between the colloid particles in the presence of surface nanobubbles are greater than those in the absence of surface nanobubbles, thereby determining the bridging effect of surface nanobubbles between the colloid particles.

[0125] Comparative Example 1

[0126] This embodiment provides a method for testing nanobubble positioning and nanobubble bridging effect similar to that of Embodiment 1, except that the surface cleaning degree of nanometer level is not achieved when cleaning the colloidal particles in step 1, and the arithmetic mean Ra of the surface roughness of the colloidal particles is 1.2 μm.

[0127] The morphology of surface nanobubbles can be scanned and the surface nanobubbles can be located, but the difference between the interaction force between colloid particles where there are surface nanobubbles and the interaction force between colloid particles where there are no surface nanobubbles cannot be tested, that is, the bridging effect of nanobubbles between colloid particles cannot be obtained. The results are as follows Figure 6 shown.

[0128] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for surface nanobubble positioning and surface nanobubble bridging effect testing, characterized in that: The method comprises: Step 1: Clean the colloidal particles to make their surface clean to nanoscale level; Step 2: Surface modification of the colloidal particles to obtain hydrophobic colloidal particles; Step 3: sticking the probe without a needle tip onto the adhesive, and then sticking the probe with the adhesive onto a single hydrophobic colloidal particle, and irradiating with ultraviolet light to obtain a colloidal probe; Step 4: fixing the colloidal probe on the scanning head of an atomic force microscope, and using the colloidal probe to scan the morphology of nanobubbles on the surface of the sample to be tested, thereby locating the nanobubbles on the surface; Step 5: using the colloidal probe to test the interaction force between colloidal particles at locations with surface nanobubbles and the interaction force between colloidal particles at locations without surface nanobubbles, and obtaining the hydrophobic attraction and hydrophobic interaction range between colloidal particles at corresponding locations; Step 6: Analyze the relationship between the hydrophobic attraction and hydrophobic interaction between the colloid particles when there are surface nanobubbles and the hydrophobic attraction and hydrophobic interaction between the colloid particles when there are no surface nanobubbles, and determine the bridging effect of the surface nanobubbles between the colloid particles.

2. The method according to claim 1, characterized in that: The particle size of the colloidal particles is 3-5 μm.

3. The method according to claim 1 or 2, characterized in that: The step 1 comprises: Step 101: Clean the beaker with piranha solution; Step 102: placing the colloidal particles in a cleaned beaker; Step 103: Add acetone to the beaker and use ultrasonic cleaning to remove contaminants on the surface of the colloidal particles; let it stand and pour out the supernatant; Step 104: Repeat step 103 at least twice; Step 105: Seal the beaker with plastic wrap, poke a plurality of holes in the plastic wrap, and place the plastic wrap in a vacuum drying oven to dry; Step 106: using oxygen plasma to remove residual organic pollutants on the surface of the dried colloidal particles, thereby obtaining colloidal particles with a surface cleanliness level of nanometers.

4. The method according to claim 1 or 2, characterized in that: In step 2, modifying the surface of the colloidal particles includes: immersing the colloidal particles in an OTS-toluene solution for modification.

5. The method according to claim 1 or 2, characterized in that: The optical microscope and the atomic force microscope are combined to realize the sequential adhesion of the adhesive and the single hydrophobic colloidal particles by the needle-free probe.

6. The method according to claim 2, characterized in that In step 103, the ultrasonic cleaning time is 1-3 minutes.

7. The method according to claim 2, characterized in that In step 103, the standing time is 1-5 minutes.

8. The method according to claim 4, characterized in that In step 2, in the OTS-toluene solution, the volume ratio of OTS to toluene is 2.5:1000-2.5:

100.

9. The method according to claim 4, characterized in that In step 2, the colloidal particles are immersed in the OTS-toluene solution for 10-15 minutes.

10. The method according to claim 1, characterized in that In step 3, the ultraviolet light irradiation time is 3-10 minutes.

Images