Method for measuring synergistic effect of flotation reagent and nanobubble bridging effect

Abstract

The invention relates to a method for measuring a synergistic effect of a flotation reagent and a nanobubble bridging effect, belongs to the technical field of interaction between colloid interfaces, and solves the problem that the nanobubble bridging effect and the synergistic effect of the nanobubble and the flotation reagent cannot be determined. Comprising the steps of cleaning colloidal particles; preparing a colloid probe; preparing nano bubbles; a colloid probe is fixed on a scanning head of an atomic force microscope, and the colloid probe is used for scanning the morphology of the nanobubbles; measuring interaction forces F01 and F02 between the colloidal particles and the sample substrate at the positions where the nano bubbles exist or not by using a colloidal probe; the method comprises the following steps: preparing a flotation system, measuring interaction forces F1 and F2 between colloidal particles with or without surface nanobubbles in a flotation reagent solution and a sample substrate in situ by using a colloidal probe, and judging the relationship between the flotation reagent and the nanobubble bridging effect by comparing the acting forces before and after the flotation reagent is added. According to the method, the synergistic effect of the flotation reagent and the nano bubble bridging effect can be directly measured.

Description

Technical Field

[0001] The invention relates to the technical field of inter-colloid interface action, and in particular to a method for measuring the synergistic action of a flotation agent and a nano-bubble bridging effect. Background Art

[0002] Flotation is widely used for the separation of fine-grained metallic minerals, non-metallic minerals, chemical raw material minerals, etc. Based on the difference in wettability of the particle surface, hydrophobic particles adhere to bubbles and float out of the solution, while hydrophilic particles remain in the solution, thereby achieving particle separation. The flotation solution contains solid particles, bubbles, flotation reagents, etc. However, it is extremely difficult for fine-grained minerals to collide and adhere to bubbles, and the flotation efficiency is significantly reduced.

[0003] Nanobubbles have attracted extensive attention from scholars in the field of flotation due to their special physical and chemical properties, such as large contact angle and long life. The introduction of nanobubbles into flotation in different ways has effectively improved the flotation effect of minerals such as coal, phosphate, scheelite and iron ore; nanobubbles also play a significant strengthening effect in the flotation treatment of petroleum wastewater and industrial wastewater.

[0004] The stronger the hydrophobicity of the particle surface, the more conducive it is to the nucleation and growth of nanobubbles. Selectively attached to the hydrophobic surface, nanobubbles promote the agglomeration of fine particles through the bridging effect, thereby increasing the apparent particle size of the particles. According to collision theory, the increase in particle size can increase the probability of collision between bubbles and mineral particles. In addition, the long-range hydrophobic force generated by the nanobubble bridging effect is also conducive to strengthening the thinning and rupture of the liquid film between particles and bubbles. However, at present, most research conclusions on the nanobubble bridging effect are obtained by flotation tests and particle interaction force tests combined with capillary force model analysis. There is no effective method to clarify the synergistic effect between the bridging effect of nanobubbles between particles and the flotation agent. Summary of the invention

[0005] In view of the above analysis, the embodiments of the present invention aim to provide a method for measuring the synergistic effect of flotation reagents and nanobubble bridging effect, so as to solve the problem that the existing methods cannot clearly define the synergistic effect of nanobubble bridging effect and flotation reagents.

[0006] In one aspect, an embodiment of the present invention provides a method for measuring the synergistic effect of a flotation agent and a nanobubble bridging effect, the method comprising:

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

[0008] Step 2: stick the probe without a needle tip onto the adhesive, and then stick the probe with the adhesive onto a single colloidal particle, and after irradiation with ultraviolet light, obtain a colloidal probe;

[0009] Step 3: Place refrigerated water in a culture dish to submerge the sample substrate to prepare nanobubbles;

[0010] Step 4: After the nanobubbles are formed, the colloidal probe is fixed on the scanning head of the atomic force microscope, and the morphology of the nanobubbles is scanned with the colloidal probe to locate the nanobubbles;

[0011] Step 5: using the colloidal probe to measure the interaction force F01 between the colloidal particles and the sample substrate at the location where the nanobubbles are present and the interaction force F02 between the colloidal particles and the sample substrate at the location where the nanobubbles are absent;

[0012] Step 6: Add the flotation agent to the culture dish, and after the flotation agent is fully dispersed, use the colloid probe to in situ measure the interaction force F1 between the colloid particles and the sample substrate at the nanobubble location and the interaction force F2 between the colloid particles and the sample substrate at the nanobubble-free location, and determine the synergistic effect of the flotation agent and the nanobubble bridging effect in the flotation system by comparing F01, F02, F1 and F2.

[0013] Preferably, the colloidal particles have a particle size of 4-6 μm.

[0014] Preferably, the colloid particles are hydrophilic colloid particles or hydrophobic colloid particles.

[0015] Preferably, when the colloidal particles are hydrophobic colloidal particles, step 1 further comprises: placing the cleaned colloidal particles in an OTS-toluene solution for surface modification, ultrasonically cleaning the surface-modified colloidal particles with toluene, acetone, and ethanol, respectively, allowing the ultrasonic solution to stand, removing the supernatant, and drying to obtain hydrophobic colloidal particles.

[0016] Preferably, in step 2, an optical microscope is combined with an atomic force microscope to achieve sequential adhesion of the adhesive and the single colloidal particles by a needle-free probe.

[0017] Preferably, in step 1, the cleaning of the colloidal particles comprises:

[0018] Step 101: Clean the beaker with piranha solution;

[0019] Step 102: placing the colloidal particles in a cleaned beaker;

[0020] 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;

[0021] Step 104: Repeat step 103 at least twice;

[0022] 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;

[0023] 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.

[0024] Preferably, in step 3, the storage temperature of the refrigerated water is 1-5°C.

[0025] Preferably, in step 3, the storage time of the refrigerated water is 2-7 days.

[0026] Preferably, in step 4, the time for waiting for the formation of nanobubbles is 30-60 minutes.

[0027] Preferably, in step 6, the flotation agent dispersion time is 30-60 minutes.

[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 first accurately locates the nanobubbles, and then tests the interaction force between particles with and without nanobubbles, thereby determining the influence of nanobubbles on the interaction force between colloidal particles and clarifying the bridging mechanism of nanobubbles.

[0030] 2. The method of the present invention can directly measure the bridging effect of nanobubbles in the interaction between colloidal particles in the flotation solution, and determine the influence of the flotation reagent in the flotation system on the bridging effect of nanobubbles, which has important value in the field of fine particle flotation.

[0031] 3. The method of the present invention is simple and applicable to various types of atomic force microscopes. Moreover, qualified colloidal probes can be prepared by strictly following the steps, thus making the method highly operable.

[0032] 4. The present invention cleans the colloidal particles with a particle size of 4-6 μm, so that the surface of the colloidal particles reaches a nano-level cleanliness level, thereby avoiding the accuracy of the nano-bubble bridging force detection in the subsequent flotation system being affected by the presence of impurities on the surface of the colloidal particles.

[0033] 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

[0034] The drawings are only for the purpose of illustrating specific embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0035] Figure 1 It is a flow chart of the method for measuring the synergistic effect of flotation reagent and nanobubble bridging effect in a flotation system of the present invention;

[0036] Figure 2 This is a nanobubble height map obtained by scanning with an atomic force microscope colloidal probe before adding a flotation agent in Example 1;

[0037] Figure 3 The force spectra between colloidal particles at the locations with and without nanobubbles measured by an atomic force microscope colloidal probe before adding a flotation agent in Example 1;

[0038] Figure 4 The interaction force between colloidal particles at the place with nanobubbles and at the place without nanobubbles measured by an atomic force microscope colloidal probe before adding the flotation agent in Example 1;

[0039] Figure 5 This is a nanobubble height map obtained by scanning with an atomic force microscope colloidal probe after adding a flotation agent in Example 1;

[0040] Figure 6 The force spectra between colloidal particles at the locations with and without nanobubbles measured by an atomic force microscope colloidal probe after adding a flotation agent in Example 1;

[0041] Figure 7 The interaction force between the colloid particles in the presence and absence of nanobubbles measured by an atomic force microscope colloid probe after adding the flotation agent in Example 1.

[0042] Reference numerals:

[0043] A-UV-ozone cleaning machine; B-hydrophilic colloid particles; C-OTS-toluene solution; D-hydrophobic colloid particles; E-atomic force microscope; F-optical microscope; G-colloid probe; H-culture dish; I-sample substrate; J-nanobubbles; K-flotation agent. DETAILED DESCRIPTION

[0044] 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.

[0045] The present invention provides a method for measuring the synergistic effect of flotation reagents and nanobubble bridging effect, such as Figure 1 As shown, the method includes:

[0046] Step 1: Clean the colloidal particles to make their surface clean to nanoscale level;

[0047] Step 2: The probe without a needle tip is attached to the adhesive, and then the probe attached to the adhesive is attached to a single colloidal particle, and after irradiation with ultraviolet light, a colloidal probe G is obtained;

[0048] Step 3: Place refrigerated water in a culture dish H to immerse the sample substrate I to prepare nanobubbles J;

[0049] Step 4: After the nanobubble J is formed, the colloidal probe G is fixed on the scanning head of the atomic force microscope, and the morphology of the nanobubble J is scanned with the colloidal probe G, so as to locate the nanobubble J;

[0050] Step 5: using the colloid probe G to measure the interaction force F01 between the colloid particles at the location with nanobubbles J and the sample substrate I and the interaction force F02 between the colloid particles at the location without nanobubbles J and the sample substrate I;

[0051] Step 6: Add the flotation agent K to the culture dish H. After the flotation agent K is fully dispersed, use the colloid probe G to in situ measure the interaction force F1 between the colloid particles at the location with nanobubbles J and the sample substrate I and the interaction force F2 between the colloid particles at the location without nanobubbles J and the sample substrate I. By comparing F01, F02, F1 and F2, it is determined that there is a nanobubble bridging effect between the colloid particles at the location with nanobubbles J and the sample substrate I, and the influence of the flotation agent on the nanobubble bridging effect in the flotation system is determined.

[0052] The method of the present invention can directly measure the bridging effect of nanobubbles in the interaction between colloidal particles in the flotation solution and determine the influence of the flotation reagent in the flotation system on the bridging effect of nanobubbles, and has important value in the research field of fine particle flotation.

[0053] Exemplarily, the colloidal particles have a particle size of 4-6 μm, such as 4 μm, 5 μm, or 6 μm.

[0054] 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.

[0055] For example, for the surface of a 200nm*200nm hydrophilic colloid particle, the arithmetic mean roughness Ra is 0.08-0.12nm.

[0056] In order to make the surface of the colloidal particles reach a nano-level cleanliness level, in step 1, the cleaning of the colloidal particles includes:

[0057] Step 101: Clean the beaker with piranha solution;

[0058] Step 102: placing the colloidal particles in a cleaned beaker;

[0059] 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;

[0060] Step 104: Repeat step 103 at least twice;

[0061] 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;

[0062] 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.

[0063] Illustratively, in step 101, the beaker may be a 10 mL beaker.

[0064] Exemplarily, in step 102, the amount of colloidal particles is 5-10 mg, such as 6 mg, 7 mg, 8 mg, 9 mg, etc. Too much particle amount is not conducive to cleaning, but too little particle amount will remain in the beaker.

[0065] Exemplarily, in step 103, the amount of acetone used is 3-5 mL, such as 3 mL, 4 mL, 5 mL, etc.

[0066] 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.

[0067] 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.

[0068] Exemplarily, in step 103, the ultrasonic cleaning is performed using an ultraviolet ozone cleaning machine A. The cleaning time of the ultraviolet ozone cleaning machine A is 10-30 minutes to ensure that all organic matter on the particle surface is removed.

[0069] 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.

[0070] Exemplarily, the colloidal particles are hydrophilic colloidal particles B or hydrophobic colloidal particles D.

[0071] When the colloidal particles are hydrophobic colloidal particles, step 1 further includes: placing the cleaned colloidal particles in an OTS-toluene solution C for surface modification, and the colloidal particles after surface modification are ultrasonically cleaned by toluene, acetone, and ethanol, respectively, and the ultrasonic solution is allowed to stand, the supernatant is removed, and the particles are dried to obtain hydrophobic colloidal particles D. The full name of OTS is octadecyltrichlorosilane, which can react with the hydroxyl groups on the surface of the particles. After the reaction, the carbon chain of OTS is retained on the surface of the colloidal particles to make the surface of the particles hydrophobic; toluene is a solvent used to dilute OTS.

[0072] For example, in the OTS-toluene solution, the volume ratio of OTS to toluene is 2.5:1000-2.5:100, such as 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 particle surface, which is not conducive to cleaning.

[0073] Exemplarily, the immersion time of the colloidal particles in the OTS-toluene solution is 5-15 minutes, such as 6 minutes, 8 minutes, 10 minutes, 12 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.

[0074] Since there is residual drug solution on the surface of the modified hydrophobic colloid particles, they need to be cleaned again with toluene, acetone and ethanol, wherein the amount of toluene used is 1-30mL, the amount of acetone used is 3-5mL, and the amount of ethanol used is 5-10mL.

[0075] Exemplarily, the standing time after ultrasonic cleaning with toluene, acetone, or ethanol is 5-10 minutes, such as 6 minutes, 7 minutes, 8 minutes, 9 minutes, etc.

[0076] Exemplarily, in step 2, the tipless probe sequentially picks up the adhesive and picks up a single colloidal particle by combining an optical microscope F with an atomic force microscope E, specifically comprising: fixing the probe on the atomic force microscope E, and under the observation of the optical microscope F, using the atomic force microscope E to control the tipless probe to first pick up the adhesive, and then pick up a single colloidal particle with the probe having the adhesive. The adhesive is used to stick a single colloidal particle to the tipless probe. The present invention combines an optical microscope F with an atomic force microscope E, so that the probe can accurately pick up the adhesive and small-size colloidal particles.

[0077] Specifically, in step 2, the adhesive is a UV-curable adhesive.

[0078] Exemplarily, the adhesive is at least one of NEA121, NOA86H and NOA89H.

[0079] In step 2, the purpose of the ultraviolet light irradiation is to cure the adhesive.

[0080] In order to fully cure the adhesive, in step 2, the ultraviolet light irradiation time is 3-10 minutes, such as 5 minutes, 7 minutes, 9 minutes, 10 minutes, etc.

[0081] Exemplarily, the intensity of the ultraviolet light is 50-60 Hz.

[0082] Exemplarily, in step 3, the storage temperature of the refrigerated water is 1-5°C to increase the air content in the water. At the same pressure, the lower the temperature, the greater the amount of dissolved gas.

[0083] Exemplarily, in step 3, the storage time of the refrigerated water is 2-7 days, and the storage time is long enough to ensure that the air in the water reaches a saturated state.

[0084] Exemplarily, the sample substrate is graphite, mica or pyrite.

[0085] Illustratively, in step 3, the method for preparing nanobubbles is the existing temperature difference method, which will not be described in detail here.

[0086] Exemplarily, in step 4, since it takes at least 30 minutes for the cold water to reach room temperature, the time for waiting for the formation of nanobubbles is 30-60 minutes.

[0087] In the present invention, in step 6, the purpose of adding the flotation agent is to form a flotation system. Exemplarily, in step 6, the flotation agent dispersion time is 30-60 minutes to ensure that the agent is fully dispersed to form a uniform flotation solution.

[0088] Exemplarily, the flotation agent is at least one of a collector, a frother, and a regulator.

[0089] Specifically, in step 4, a colloidal probe is used to scan the morphology of nanobubbles, thereby locating the nanobubbles, including: using a colloidal probe G to scan an area range of the sample to be tested, in which there must be areas with nanobubbles and areas without nanobubbles, and the colloidal probe G 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 and locate the nanobubbles according to the different surfaces of the substrate.

[0090] It should be noted that in step 5, the colloid probe G is used to test the interaction force F01 between the colloid particles and the sample substrate at the location with nanobubbles and the interaction force F02 between the colloid particles and the sample substrate at the location without nanobubbles, including: the colloid probe is still fixed on the atomic force microscope E, and the colloid probe is used to perform a force curve test in the same range as step 4, the colloid probe transmits the test signal to the atomic force microscope E, and after receiving the data, the atomic force microscope E displays the test results of the force curves at various locations within the range, including the interaction force F01 between the colloid particles and the sample substrate at the location with nanobubbles and the interaction force F02 between the colloid particles and the sample substrate at the location without nanobubbles. 02, since the nanobubbles in this 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 colloidal particles and the sample substrate at the location where there are nanobubbles, the gravitational force and range between the colloidal particles and the sample substrate at the location where there are nanobubbles are obtained; based on the interaction force between the colloidal particles and the sample substrate at the location where there are no nanobubbles, the gravitational force and range between the colloidal particles and the sample substrate at the location where there are no surface nanobubbles are obtained; specifically, in the process of the colloidal particles approaching the substrate, a negative value will be generated on the needle force curve between the two, and this negative value is the gravitational force between the two, and the position where the negative value begins to be generated is the range corresponding to the gravitational force. Comparing F01 and F02, the results show that the range of F01 is greater than that of F02, and it can be determined that there is a nanobubble bridging effect between the colloidal particles and the sample substrate at the location where there are nanobubbles.

[0091] It should be noted that step 6 includes: adding the flotation agent K to the culture dish H, and forming a flotation system after the flotation agent K is fully dispersed; the colloid probe is still fixed on the atomic force microscope E, and the colloid probe is used to perform morphology scanning and force curve testing in the same range as step 4, and the colloid probe transmits the test signal to the atomic force microscope E. After receiving the data, the atomic force microscope E displays the test results of the force curves at various locations within the range, including the interaction force F1 between the colloid particles and the sample substrate at the location with nanobubbles and the interaction force F2 between the colloid particles and the sample substrate at the location without nanobubbles; comparing the sizes of F01, F02, F1 and F2 and the corresponding ranges of action. The results show that the action range corresponding to F01 is greater than that corresponding to F02, and the action range corresponding to F1 is greater than that corresponding to F2 (the action range is compared here, because whether it is hydrophilic or hydrophobic colloid particles, the nanobubble bridging effect will increase the interaction range between the colloid particles and the substrate, but due to the different hydrophilicity and hydrophobicity of the colloid surface, the change in the magnitude of the force is different and cannot be directly compared). It can be determined that there is a nanobubble bridging effect between the colloid particles at the nanobubble location and the sample substrate; and by comparing the relationship between the size and the corresponding action range between F01 and F1, the effect of the flotation agent on the nanobubble bridging effect in the flotation system can be determined. In other words, by comparing the changes in the magnitude and action range of the interaction force between the colloid particles at the nanobubble location and the substrate before and after the addition of the flotation agent, the effect of the flotation agent on the nanobubble bridging effect can be obtained. Specifically, if the magnitude of the interaction force and the range of action between the colloidal particles and the substrate at the location where the nanobubbles are present before the flotation agent is added are greater than the magnitude of the interaction force and the range of action between the colloidal particles and the substrate at the location where the nanobubbles are present after the flotation agent is added, then the flotation agent inhibits the bridging effect of the nanobubbles between the colloidal particles; if the magnitude of the interaction force and the range of action between the colloidal particles and the substrate at the location where the nanobubbles are present before the flotation agent is added are less than the magnitude of the interaction force and the range of action between the colloidal particles and the substrate at the location where the nanobubbles are present after the flotation agent is added, then the flotation agent enhances the bridging effect of the nanobubbles between the colloidal particles.

[0092] The method for measuring the synergistic effect of the flotation reagent and the nanobubble bridging effect in the flotation system of the present invention is further described below through specific examples.

[0093] Example 1

[0094] This embodiment provides a method for measuring the synergistic effect of a flotation agent and a nanobubble bridging effect in a flotation system, comprising:

[0095] Step 1: Clean the colloidal particles to make their surface clean at the nanoscale:

[0096] Step 101: Wash a 10 mL beaker with piranha solution;

[0097] Step 102: placing colloidal particles weighing 6 mg and having a particle size of 5 μm in a cleaned beaker;

[0098] 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;

[0099] Step 104: Repeat step 103 twice;

[0100] 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 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.

[0101] Step 106: using oxygen plasma 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 (the arithmetic mean value of the roughness Ra is 0.1 nm).

[0102] The cleaned colloidal particles are placed in an OTS-toluene solution for surface modification. The surface-modified colloidal particles are respectively ultrasonically cleaned with toluene, acetone, and ethanol. The ultrasonic solution is allowed to stand, the supernatant is removed, and the particles are dried to obtain hydrophobic colloidal particles.

[0103] The volume ratio of OTS to toluene is 2.5:700; the immersion time of the colloidal particles in the OTS-toluene solution is 10 min; the amount of toluene used is 3 mL, the amount of acetone used is 4 mL, and the amount of ethanol used is 6 mL; and the standing time is 7 min.

[0104] Step 2: Fix the tipless probe on the atomic force microscope. Under optical microscope observation, use the atomic force microscope to control the tipless probe to first stick to the adhesive, and then stick the probe with the adhesive to a single hydrophobic colloid particle. After irradiating with ultraviolet light for 7 minutes, the adhesive is solidified to obtain a hydrophobic colloid probe.

[0105] Step 3: Place refrigerated water with a storage temperature of 4°C and a storage time of 5 days in a culture dish to immerse the sample substrate to prepare nanobubbles;

[0106] Step 4: After waiting for 40 minutes for nanobubbles to form, the hydrophobic colloid probe is fixed on the scanning head of the atomic force microscope, and a region of the sample to be tested is scanned with the hydrophobic colloid probe. There must be areas with nanobubbles and areas without nanobubbles in the region. The hydrophobic colloid probe 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 nanobubbles; Figure 2 shown.

[0107] Step 5: The hydrophobic colloid probe is still fixed on the atomic force microscope, and the hydrophobic colloid probe is used to perform a force curve test in the same range as step 4. The hydrophobic colloid probe transmits the test signal to the atomic force microscope. After receiving the data, the atomic force microscope displays the test results of the force curves at various locations within the range, including the interaction force F01 between the colloid particles and the sample substrate at the location with nanobubbles and the interaction force F02 between the colloid particles and the sample substrate at the location without nanobubbles, such as Figure 3 shown; according to Figure 3 The needle-insertion interaction force curves between the colloidal particles and the sample substrate at the place without nanobubbles and the needle-insertion interaction force curves between the colloidal particles and the sample substrate at the place with nanobubbles are obtained, such as Figure 4 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 the interaction force F02 between the colloid particles and the sample substrate where there are no surface nanobubbles has almost no attraction, while the interaction force F01 between the colloid particles and the sample substrate where there are surface nanobubbles produces a "jump-in" attraction at a distance of 59.1nm, that is, the range of action is 59.1nm, and the maximum hydrophobic attraction between the colloid particles and the sample substrate is 83.0nN; by comparing F01 and F02, the results show that the force and range of F01 are greater than F02, which can determine that there is a nanobubble bridging effect between the colloid particles and the sample substrate where there are nanobubbles.

[0108] Step 6: Add 2M inorganic salt of flotation reagent into the culture dish. After the flotation reagent is fully dispersed for 40 minutes, a flotation system is formed. The hydrophobic colloid probe is still fixed on the atomic force microscope and the hydrophobic colloid probe is used to perform morphological scanning in the same range as step 4. The results are as follows: Figure 5 As shown; a force curve test is performed with a hydrophobic colloid probe in the same range as step 4, and the test results of the force curves at various locations within the range are displayed, including the interaction force F1 between the colloid particles and the sample substrate at the location with nanobubbles and the interaction force F2 between the colloid particles and the sample substrate at the location without nanobubbles, as shown Figure 6 As shown; analysis Figure 6 The interaction force between the colloidal particles and the sample substrate where there are nanobubbles and the interaction force between the colloidal particles and the sample substrate where there are no nanobubbles are taken into account, and one set of needle force curves is obtained, such as Figure 7 shown by Figure 7It can be seen that the interaction force F2 between the colloid particles and the sample substrate at the place without surface nanobubbles has almost no attraction, while the interaction force F1 between the colloid particles and the sample substrate at the place with surface nanobubbles produces a "jump-in" attraction at a distance of 40.8nm, that is, the range of action is 40.8nm, and the maximum hydrophobic attraction between the colloid particles is 5.3nN; by comparing the relationship between the force and range of action between F01 and F1, it is found that the force and range before adding 2M flotation agent inorganic salt are greater than the force and range after adding 2M flotation agent inorganic salt. It can be judged that the 2M flotation agent inorganic salt in the flotation system inhibits the bridging effect of nanobubbles between colloid particles.

[0109] Example 2

[0110] This embodiment provides a method for measuring the synergistic effect of a flotation agent and a nanobubble bridging effect in a flotation system, comprising:

[0111] Step 1: Clean the colloidal particles to make their surface clean at the nanoscale:

[0112] Step 101: Wash a 10 mL beaker with piranha solution;

[0113] Step 102: placing 8 mg of colloidal particles with a particle size of 6 μm in a cleaned beaker;

[0114] 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;

[0115] Step 104: Repeat step 103 twice;

[0116] 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 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.

[0117] Step 106: using oxygen plasma to remove residual organic pollutants on the surface of the dried colloidal particles, to obtain hydrophilic colloidal particles with a surface cleanliness level at the nanometer level (arithmetic mean roughness Ra is 0.1 nm).

[0118] Step 2: Fix the tipless probe on the atomic force microscope. Under optical microscope observation, use the atomic force microscope to control the tipless probe to first stick to the adhesive, and then stick the probe with the adhesive to a single hydrophilic colloid particle. After irradiating with ultraviolet light for 8 minutes, the adhesive is solidified to obtain a hydrophilic colloid probe.

[0119] Step 3: Place refrigerated water with a storage temperature of 3°C and a storage time of 4 days in a culture dish to immerse the sample substrate to prepare nanobubbles;

[0120] Step 4: After waiting for 50 minutes for the nanobubbles to form, the hydrophilic colloid probe is fixed on the scanning head of the atomic force microscope, and the hydrophilic colloid probe is used to scan an area of ​​the sample to be tested. There must be areas with nanobubbles and areas without nanobubbles in this area. The hydrophilic colloid probe transmits the scanning signal to the atomic force microscope. After receiving the data, the atomic force microscope identifies the morphology of the nanobubbles and locates the nanobubbles.

[0121] Step 5: The hydrophilic colloid probe is still fixed on the atomic force microscope, and the hydrophilic colloid probe is used to perform a force curve test in the same range as step 4. The hydrophilic colloid probe transmits the test signal to the atomic force microscope. After receiving the data, the atomic force microscope displays the test results of the force curves at various locations within the range, including the interaction force F01 between the colloid particles and the sample substrate at the location with nanobubbles and the interaction force F02 between the colloid particles and the sample substrate at the location without nanobubbles; by analyzing the interaction force between the colloid particles at the location with and without nanobubbles, one set of needle insertion force curves is obtained. According to the needle insertion force curves F01 and F02 corresponding to the action range F01 action range is greater than F02 action range, it can be determined that there is a nanobubble bridging effect between the colloid particles at the location with nanobubbles and the sample substrate.

[0122] Step 6: Add the flotation agent to the culture dish, wait for the flotation agent to be fully dispersed for 40 minutes, form a flotation system, fix the hydrophilic colloid probe on the atomic force microscope, use the hydrophilic colloid probe to perform morphology scanning and interaction force test in the same range as step 4, the hydrophilic colloid probe transmits the scanning signal to the atomic force microscope, and after receiving the data, the atomic force microscope displays the test results of the surface morphology and force curves in the range, including the interaction force F1 between the colloid particles and the sample substrate at the nanobubble location and the interaction force F2 between the colloid particles and the sample substrate at the non-nanobubble location. By comparing F01, F02, F1 and F2, the results show that the F01 action range is greater than F02, and the F1 action range is greater than F2. It can be determined that there is a nanobubble bridging effect between the colloid particles and the sample substrate at the nanobubble location, and by comparing the relationship between the action force and action range between F01 and F1, the influence of the flotation agent on the nanobubble bridging effect in the flotation system can be judged.

[0123] Comparative Example 1

[0124] This comparative example provides a method for measuring the synergistic effect of flotation reagent and nanobubble bridging effect in a flotation system similar to Example 1, except that the surface nanoscale cleaning level is not achieved when washing the colloidal particles in step 1.

[0125] The morphology of surface nanobubbles can be scanned and the surface nanobubbles can be located, but the difference between the interaction force between colloidal particles where there are surface nanobubbles and the interaction force between colloidal particles where there are no surface nanobubbles cannot be tested, that is, the bridging effect of nanobubbles between colloidal particles cannot be obtained.

[0126] 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 measuring the synergistic effect of flotation reagents and nanobubble bridging effect, characterized in that: The method comprises: Step 1: Clean the colloidal particles to make their surface clean to nanoscale level; Step 2: stick the probe without a needle tip onto the adhesive, and then stick the probe with the adhesive onto a single colloidal particle, and after irradiation with ultraviolet light, obtain a colloidal probe; Step 3: Place refrigerated water in a culture dish to submerge the sample substrate to prepare nanobubbles; Step 4: After the nanobubbles are formed, the colloidal probe is fixed on the scanning head of the atomic force microscope, and the morphology of the nanobubbles is scanned with the colloidal probe to locate the nanobubbles; Step 5: using the colloidal probe to measure the interaction force F01 between the colloidal particles and the sample substrate at the location where the nanobubbles are present and the interaction force F02 between the colloidal particles and the sample substrate at the location where the nanobubbles are absent; Step 6: Add the flotation agent to the culture dish, and after the flotation agent is fully dispersed, use the colloid probe to in situ measure the interaction force F1 between the colloid particles and the sample substrate at the nanobubble location and the interaction force F2 between the colloid particles and the sample substrate at the nanobubble-free location, and determine the synergistic effect of the flotation agent and the nanobubble bridging effect in the flotation system by comparing F01, F02, F1 and F2.

2. The method according to claim 1, characterized in that The particle size of the colloidal particles is 4-6 μm.

3. The method according to claim 2, characterized in that The colloidal particles are hydrophilic colloidal particles or hydrophobic colloidal particles.

4. The method according to claim 3, characterized in that When the colloidal particles are hydrophobic colloidal particles, step 1 further comprises: placing the cleaned colloidal particles in an OTS-toluene solution for surface modification, ultrasonically cleaning the surface-modified colloidal particles with toluene, acetone, and ethanol, respectively, allowing the ultrasonic solution to stand, removing the supernatant, and drying to obtain hydrophobic colloidal particles.

5. The method according to claim 1, characterized in that In step 2, an optical microscope is combined with an atomic force microscope to realize the tip-free probe to sequentially pick up the adhesive and the single colloidal particles.

6. The method according to claim 1, characterized in that In step 1, the cleaning of the colloidal particles 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.

7. The method according to claim 1, characterized in that In step 3, the storage temperature of the refrigerated water is 1-5°C.

8. The method according to claim 1, characterized in that In step 3, the storage time of the refrigerated water is 2-7 days.

9. The method according to claim 1, characterized in that: In step 4, the time for waiting for the formation of nanobubbles is 30-60 minutes.

10. The method according to claim 1, characterized in that In step 6, the flotation agent dispersion time is 30-60 minutes.

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