CN114577716A - A method for screening the molecular functional groups of coal slime flotation collectors - Google Patents

Abstract

The invention discloses a method for screening coal slime flotation collector molecular functional groups, which belongs to the field of flotation reagent design. Modified probes with different flotation reagent molecular functional groups were prepared by deposition, and then the elastic deformation information generated during the injection of the modified probe into the tested coal sample was observed by atomic force microscope AFM, and the modified probe was deduced according to the elastic deformation information. The needle insertion force information of the sex probe during the needle insertion process was collected, and the needle withdrawal force information corresponding to the modified probe was collected to generate the needle withdrawal force curve; the values of the needle withdrawal force curves of all modified probes were compared. The greater the adhesion between the flotation collector molecular functional groups on the sex probe and the coal sample, the greater the adhesion, the better the effect of the collector deposited on the modified probe. The method has simple steps, high precision and intuition, and solves the problems in the prior art, such as difficulty in screening the molecular functional groups of high-efficiency collectors, unclear regulation mechanism of collectors, and the like.

Description

A method for screening the molecular functional groups of coal slime flotation collectors

technical field

The invention relates to a method for directional screening and design of molecular functional groups of coal slime flotation collectors, belonging to the field of flotation reagent design.

Background technique

Flotation is an effective way for fine-grained slime separation and efficient resource recovery and utilization. It is an interface separation technology to effectively separate useful minerals and gangue minerals according to the different physical and chemical properties of mineral surfaces. The collector is a flotation agent that selectively adsorbs on the mineral surface, thereby improving the hydrophobicity of the mineral surface and making it easy to adhere to the air bubbles. The interaction between the collector and the mineral surface is the precondition for determining the flotation efficiency. At present, traditional fossil fuels represented by non-polar hydrocarbon oil, petrochemical by-products, etc. are the main sources of coal slime flotation collectors. The selection of reagents relies on empirical exploration, lacks scientific basis, and has poor adaptability to coal types. Poor, seriously restricting the improvement of slime flotation efficiency and the high-quality development of the coal industry. In recent years, a series of progress has been made in the regulation mechanism of collectors in the flotation process, but the molecular structure information of collectors is still unclear, and its mechanism of action still needs to be explored. The design and development of efficient collectors lack the support of science and technology .

Surface forces mainly include van der Waals force, electrostatic force, hydration force, hydrophobic force, etc., which directly determine the interaction between collector and coal surface. At present, the adsorption behavior of chemicals on the coal surface at the micro-nano scale has attracted extensive attention of scholars in the field of flotation colloid chemistry, and a series of experimental techniques for studying the interaction between coal and chemicals have gradually emerged. Traditional surface detection techniques such as Fourier Transform Infrared Absorption Spectrometer (FTIR), X-ray Photoelectron Spectroscopy (XPS) are usually non-real-time or non-in situ measurements obtained in a vacuum or air-drying environment, and cannot realize the flotation liquid phase environment. In situ testing, quartz crystal microbalance (QCM-D) characterizes the adsorption behavior of the agent by monitoring the mass change of the surface to be tested, and the morphology of the polymer adsorption layer is imaged by atomic force microscope (AFM) to explore the adsorption behavior of the agent on the coal surface However, none of the above methods can directly measure the interaction force between the agent molecule and the coal surface, resulting in the lack of the interaction force between the agent molecule and the coal surface.

Therefore, there is an urgent need to propose a method for directional screening of collector molecular functional groups. The chemical force spectroscopy test method based on atomic force microscopy is an important means to screen collectors that match the properties of coal surface. The development of the field is of great significance.

SUMMARY OF THE INVENTION

Aiming at the shortcomings of the prior art, a simple, high-precision and intuitive method for screening the molecular functional groups of coal slime flotation collectors is provided, so as to solve the difficulty in screening the molecular functional groups of efficient collectors in the prior art, and the The control mechanism is not clear and so on.

In order to achieve the above-mentioned technical purpose, a method for screening the molecular functional groups of a coal slime flotation collector of the present invention, the steps are as follows:

Step 1. Immerse a plurality of gold-plated probes in an ethanol solution of mercapto compounds containing different collector molecular functional groups for 24 hours, thereby chemically depositing different flotation collector molecular functional groups on the surface of each gold-plated probe to form Modified probes with different flotation collector molecular functional groups are deposited on the surface, and each modified probe is marked;

Step 2. Fix the coal sample with a smooth and flat upper surface on the substrate, and then place the substrate on the AFM stage of the atomic force microscope;

Step 3. Install the bottomless annular rubber ring on the bottom of the liquid pool, take a modified probe and install it on the clip in the middle of the liquid pool, put the liquid pool on the special support table, so that the tip of the modified probe is suspended in the liquid pool. the upper surface of the coal sample;

Step 4. Adjust the position of the stage under the condition of fixing the position of the modified probe so that the coal sample is close to the tip of the modified probe, and then fix the position of the stage. At this time, the rubber ring is located on the bottom of the liquid pool and on the coal sample between surfaces and form a sealed space;

Step 5. Fill the space surrounded by the rubber ring between the bottom surface of the liquid pool and the upper surface of the coal sample with the inorganic salt solution; control the solution of the inorganic salt solution to ensure that each test condition is consistent;

Step 6. Use piezoelectric ceramics to control the modified probe to continuously insert the needle to the upper surface of the coal sample, and collect the elastic deformation information generated by the modified probe during the needle insertion process, and deduce the modified probe according to the elastic deformation information. Needle insertion force information during the needle process, the needle insertion force increases with the approach of the modified probe to the upper surface of the coal sample. When the needle insertion force has a linear relationship with the distance, it is judged that the end of the modified probe has physically contacted the coal. At this time, the needle withdrawal is performed to control the modified probe away from the coal sample, and the needle withdrawal force information corresponding to the modified probe is collected at the same time. force curve;

Step 7. Repeat steps 2 to 6 to obtain the needle insertion force curve and needle withdrawal force curve of the modified probes with different flotation collector molecular functional groups deposited on each surface and coal samples, and compare the withdrawal force curves of all modified probes. The value of the needle force curve, the larger the value, the greater the adhesion between the flotation collector molecular functional groups on the modified probe and the coal sample, the greater the adhesion, the greater the adhesion force deposited on the modified probe. The better the collector works.

Further, all the different flotation collectors deposited on the gold-plated probes are sorted by the adhesion of each modified probe, so as to screen out the best flotation collector for coal samples; So as to compare the flotation collectors with the best flotation effect of different types of coal samples.

Further, the inorganic salt solution and the coal sample in the space surrounded by the rubber ring between the bottom surface of the liquid pool and the upper surface of the coal sample need to be replaced each time a different modified probe is replaced and tested; The liquid outlet pipe realizes the rapid replacement of the inorganic salt solution, and the concentration of the inorganic salt solution is controlled to be consistent in each test;

Further, the nominal elastic modulus of the gold-plated probe for preparing the modified probe is 0.08 N/m.

Further, before preparing the modified probe, the gold-plated probe needs to be placed in a plasma cleaning machine for 10 minutes, and then soaked in an ethanol solution for 5 minutes to remove contaminants.

Further, after the gold-plated probes form modified probes with different flotation collector molecular functional groups deposited on the surface, the modified probes must be soaked in ethanol and ultrapure water for 10 minutes in turn, and then placed in a vacuum drying box. Reserve after drying.

Further, the coal sample is cut into a flat structure and the surface is polished smooth, and then cleaned to ensure no contamination.

Further, before the modified probe is inserted into the needle, it is necessary to measure the deflection sensitivity of the probe cantilever of the modified probe and calculate the actual elastic coefficient of the probe cantilever to complete the elastic coefficient correction to ensure the accuracy of the force test data; After that, the modified probe is controlled by piezoelectric ceramics to enter and move away from the surface of the coal sample to obtain force information. Each modified probe is repeatedly inserted and withdrawn at different positions of the coal sample to obtain the modified probe. For the adhesion force at different positions of the coal sample, the average value of the adhesion force collected at different positions is taken to ensure the representativeness and accuracy of the force curve test.

Further, the force test results of the needle withdrawal curve were fitted with a normal distribution to determine the adhesion force between the modified probe and the coal sample; the EDLVO theory was used to fit the needle insertion force curve to determine the van der Waals interaction force. Components of force, electrostatic force, and hydrophobic force.

Beneficial effects:

1. The method for directional screening of collector molecular functional groups proposed by the present invention can directly compare the mechanical interaction between various collector molecules and the coal surface, thereby screening the best collector and breaking through the drawbacks of blindly relying on traditional empirical guidance.

2. Compared with the traditional technology, the method for screening collector molecular functional groups provided by the present invention can perform in-situ measurement in a liquid phase environment, and the test conditions are close to the interaction between the collector and the surface of coal minerals in the flotation environment.

3. The method for screening collector molecular functional groups provided by the present invention can regulate the chemical conditions of the solution and provide various test conditions.

4. The method for screening collector molecular functional groups provided by the present invention can quickly screen out the effective functional groups in the collector, and directly guide the design and development of pharmaceuticals.

5. The method for screening collector molecular functional groups provided by the present invention can quantitatively analyze the mechanical information between the agent and the coal surface, which is beneficial to clarify the regulation mechanism of the collector.

Description of drawings

Fig. 1 is the schematic diagram of the molecular orientation screening test of collector of the present invention;

2 is a typical force-distance curve measured by the undecane-modified probe of Example 1 of the present invention and the graphite surface needle insertion in a liquid phase environment;

3 is a typical force-distance curve measured by the undecane-modified probe of Example 1 of the present invention in a liquid phase environment and the graphite surface withdrawn from the needle;

FIG. 4 is a typical force-distance curve measured by the undecanoic acid-modified probe of Example 2 of the present invention and the graphite surface in a liquid phase environment.

FIG. 5 is a typical force-distance curve measured by the undecanoic acid modified probe of Example 2 of the present invention and the graphite surface withdrawn in a liquid phase environment.

In the figure: 1-laser light source; 2-prism; 3-laser detector; 4-scanner; 5-liquid cell; 6-gold-plated probe; 7-collector molecular functional group; 8-bottomless annular rubber ring; 9-mineral sample; 10-substrate; 11-stage; 12-liquid inlet; 13-outlet; 14-modified probe.

Detailed ways:

In order to further understand the present invention, the preferred embodiments of the present invention are specifically described below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present application, and together with the present invention, are used to illustrate the features and advantages of the present invention, but not to limit the present invention. range.

As shown in FIG. 1 , the method for screening the molecular functional groups of a coal slime flotation collector of the present invention uses an atomic force microscope AFM, which includes a laser light source 1 , a prism 2 , a laser detector 3 and a scanner 4

The steps are as follows:

Step 1. Immerse a plurality of gold-coated probes 6 in an ethanol solution of mercapto compounds containing different collector molecular functional groups for 24 hours to prepare the gold-coated probes 6 of the modified probes 14. The nominal elastic coefficient is 0.08 N/m , so that different flotation collector molecular functional groups 7 are chemically deposited on the surface of each gold-plated probe 6 to form modified probes 14 with different flotation collector molecular functional groups 7 deposited on the surface, and each modified probe 14 is marked; before preparing the modified probe 14, the gold-plated probe 6 needs to be placed in a plasma cleaning machine for 10 minutes, placed in an ethanol solution for 5 minutes to remove contaminants, and a surface deposition is formed on the gold-plated probe 6 After the modified probes 14 with different flotation collector molecular functional groups 7, the modified probes 14 must be immersed in ethanol and ultrapure water for 10 minutes in turn, and then put into a vacuum drying box for drying before use.

Step 2. Fix the coal sample 9 with a smooth and flat upper surface on the substrate 10, and then place the substrate 10 on the AFM stage 11 of the atomic force microscope; the coal sample 9 is cut into a flat structure and the surface is polished smooth, and then cleaned Guaranteed no pollution.

Step 3. Install the bottomless annular rubber ring 8 on the bottom of the liquid pool 5, take a modified probe 14 and install it on the clip in the middle of the liquid pool 5, put the liquid pool 5 on the special support table, and make the modified probe 14. The tip of the needle 14 is suspended on the upper surface of the coal sample 9;

Step 4. With the position of the modified probe 14 fixed, adjust the position of the stage 11 so that the coal sample 9 is close to the tip of the modified probe 14, and then fix the position of the stage 11, and the rubber ring is located in the liquid pool 5 between the bottom surface and the upper surface of the coal sample 9 and form a sealed space;

Step 5. Fill the space surrounded by the rubber ring 8 between the bottom surface of the liquid pool 5 and the upper surface of the coal sample 9 with the inorganic salt solution; the bottom surface of the liquid pool 5 and the coal sample need to be replaced each time a different modified probe 14 is replaced and tested 9. The inorganic salt solution and the coal sample 9 in the space surrounded by the rubber ring 8 between the upper surfaces; by setting the liquid inlet pipe 12 and the liquid outlet pipe 13 on the rubber ring 8 to realize the rapid replacement of the inorganic salt solution, control each test The concentration of inorganic salt solution is the same;

Step 6. Use piezoelectric ceramics to control the modified probe 14 to continuously insert the needle into the upper surface of the coal sample 9, and collect the elastic deformation information generated by the modified probe 14 during the needle insertion process, and deduce the modified probe according to the elastic deformation information. The information of the needle insertion force of the needle 14 during the needle insertion process. The needle insertion force increases as the modified probe 14 approaches the upper surface of the coal sample 9. When the needle insertion force and the distance show a linear relationship, the modified probe 14 is judged. The end of the coal sample 9 has physically contacted the upper surface of the coal sample 9. At this time, the needle retraction is performed to control the modified probe 14 away from the coal sample 9. At the same time, the needle retraction force information corresponding to the modified probe 14 is collected. Needle force information to generate needle insertion force curve and needle withdrawal force curve;

Step 7. Repeat steps 2 to 6 to obtain the needle insertion force curve and the needle withdrawal force curve of the modified probe 14 and the coal sample 9 with different flotation collector molecular functional groups 7 deposited on each surface, and compare all modified probes. The value of the needle withdrawal force curve of the needle 14, the larger the value, the greater the adhesion between the flotation collector molecular functional group 7 on the modified probe 14 and the coal sample 9, and the greater the adhesion, the greater the adhesion. The collector deposited on the modified probe 14 is more effective. All the different flotation collectors deposited on the gold-coated probes 6 are sorted by the adhesion force of the individual modified probes 14 to screen out the best flotation collectors for the coal sample 9; by changing the coal sample 9 types, so as to compare the flotation collectors with the best flotation recovery effect for different types of coal samples.

Before the modified probe 14 is inserted into the needle, it is necessary to measure the deflection sensitivity of the probe cantilever of the modified probe 14 and calculate the actual elastic coefficient of the probe cantilever to complete the elastic coefficient correction to ensure the accuracy of the force test data; Then, the piezoelectric ceramics are used to control the modified probe 14 to enter and move away from the surface of the coal sample 9 to obtain force information. For the adhesion force between the modified probe 14 and the coal sample 9 at different positions, the average value of the adhesion force collected at different positions is taken, so as to ensure the representativeness and accuracy of the force curve test.

Fit the normal distribution of the force test results of the needle withdrawal curve to determine the adhesion force between the modified probe 14 and the coal sample 9; use the EDLVO theory to fit the needle insertion force curve to determine the van der Waals interaction force Components of force, electrostatic force, and hydrophobic force.

The coal sample 9 can be replaced by the following surfaces: graphite substrate, graphite oxide substrate, silicon substrate, silanized silicon substrate, glass flake substrate, silanized glass flake substrate, gold flake, mica flake; gold-plated probe 6 and collector The fixation method of molecule 7 is chemical bonding;

The present invention is further described below with reference to the embodiments and the accompanying drawings. The detection technology adopted in the embodiment is the above-mentioned technology.

Example 1. Interaction between undecane and graphite surface

Step 1. Soak the gold-plated probes 6 in 1 mM ethanol solution of 1-mercapto-undecane for 24 hours, and obtain the modified probes 14 covered with undecane molecules 7 by chemical deposition;

Step 2. Place the substrate 10 on which the graphite sheet 9 is fixed on the AFM stage 11;

Step 3, place the liquid pool 5 equipped with the gold-plated probe 6 above the graphite sheet 9, adjust the position of the rubber ring 8 to ensure sealing, and feed 0.5M NaCl solution;

Step 4. Obtain the force curve and analyze it.

Figures 2 and 3 are typical force-distance curves measured by the interaction of the undecane-modified probe 14 of Example 1 with the graphite surface 9 in a liquid phase environment. As can be seen from Fig. 2 and Fig. 3, the test method of the present invention can test the interaction force between the collector molecule 7 and the graphite surface 9 in-situ in a liquid phase environment.

Example 2. Interaction between undecanoic acid and graphite surface

Step 1, soak the gold-plated probe 6 in the ethanol solution of 1mM 1-mercapto-undecanoic acid for 24 hours respectively, and obtain the modified probe 14 covered with the undecanoic acid molecule 7 by chemical deposition;

Step 2, placing the base 10 for fixing the graphite sheet 9 on the AFM stage 11;

Step 3, place the liquid pool 5 equipped with the gold-plated probe 6 above the graphite sheet 9, adjust the position of the rubber ring 8 to ensure sealing, and feed 0.5M NaCl solution;

Step 4. Obtain the force curve and analyze it.

Figures 4 and 5 are typical force-distance curves measured by the interaction of the undecanoic acid-modified probe 14 of Example 2 with the graphite surface 9 in a liquid phase environment. As can be seen from Figure 4 and Figure 5, the test method of the present invention can test the interaction force between the collector molecules 7 and the graphite surface 9 in situ in a liquid phase environment.

The present invention utilizes the prior art to simply transform the test method to control different solution chemical environments and different collector molecules, provides various test conditions and is easy to operate.

Claims (9)

1. A method for screening the molecular functional group of a coal slime flotation collector is characterized by comprising the following steps:

step 1, placing a plurality of gold-plated probes (6) in ethanol solution of mercapto compounds containing different collector molecular functional groups, soaking for 24 hours, so that different flotation collector molecular functional groups are chemically deposited on the surface of each gold-plated probe (6), modified probes (14) with different flotation collector molecular functional groups deposited on the surface are formed, and labeling each modified probe (14);

step 2, fixing the coal sample (9) with a smooth and flat upper surface on a substrate (10), and then placing the substrate (10) on an AFM (atomic force microscope) objective table (11);

step 3, installing a bottomless annular rubber ring (8) at the bottom of the liquid pool (5), installing a modified probe (14) on a clamp in the middle of the liquid pool (5), and placing the liquid pool (5) on a special supporting table to enable the tip of the modified probe (14) to be suspended on the upper surface of the coal sample (9);

step 4, under the condition that the position of the modification probe (14) is fixed, adjusting the position of the objective table (11) to enable the coal sample (9) to be close to the tip position of the modification probe (14), and then fixing the position of the objective table (11), wherein the rubber ring is located between the bottom surface of the liquid pool (5) and the upper surface of the coal sample (9) and forms a sealed space;

step 5, filling inorganic salt solution into a space surrounded by the rubber ring (8) between the bottom surface of the liquid pool (5) and the upper surface of the coal sample (9); controlling the solution of the inorganic salt solution to ensure that the test conditions are consistent each time;

step 6, continuously inserting the modified probe (14) to the upper surface of the coal sample (9) by utilizing the piezoelectric ceramics, simultaneously collecting elastic deformation information generated by the modified probe (14) in the needle inserting process, deducing needle inserting force information of the modified probe (14) in the needle inserting process according to the elastic deformation information, wherein the needle inserting force is increased along with the approach of the modified probe (14) to the upper surface of the coal sample (9), judging that the end part of the modified probe (14) is in physical contact with the upper surface of the coal sample (9) after the needle inserting force and the distance present a linear relation, withdrawing the needle at the moment, namely, controlling the modified probe (14) to be far away from the coal sample (9), simultaneously collecting needle withdrawing force information corresponding to the modified probe (14), and generating a needle inserting force curve and a needle withdrawing force curve by using the needle inserting force information and the needle withdrawing force information;

and 7, repeating the steps 2 to 6, obtaining a needle inserting force curve and a needle withdrawing force curve of each modified probe (14) with different flotation collector molecule functional groups deposited on the surface and the coal sample (9), comparing needle withdrawing force curve values of all the modified probes (14), wherein the larger the value is, the larger the adhesion force between the flotation collector molecule functional groups on the modified probes (14) and the coal sample (9) is, and the larger the adhesion force is, the better the effect of the collector deposited on the modified probes (14) is.

2. The method for screening the molecular functional groups of the coal slime flotation collector according to claim 1, characterized by comprising the following steps: sorting all different flotation collectors deposited on the gold-plating probes (6) by using the adhesive force of each modified probe (14), so as to screen out the best flotation collector for the coal sample (9); by changing the types of the coal samples (9), the flotation collecting agent with the best flotation recovery effect of different types of coal samples (9) is compared.

3. The method for screening the molecular functional groups of the coal slime flotation collector according to claim 1, characterized by comprising the following steps: the inorganic salt solution and the coal sample (9) in the space surrounded by the rubber ring (8) between the bottom surface of the liquid pool (5) and the upper surface of the coal sample (9) need to be replaced each time the modified probe (14) with different tests is replaced; the quick replacement of the inorganic salt solution is realized by arranging the liquid inlet pipe (12) and the liquid outlet pipe (13) on the rubber ring (8), and the concentration of the inorganic salt solution in each test is controlled to be consistent.

4. The coal slime flotation collector molecular functional group directional screening design method according to claim 1, characterized in that: the nominal modulus of elasticity of the gold-plated probe (6) for preparing the modified probe (14) was 0.08N/m.

5. The method for screening the molecular functional groups of the coal slime flotation collector according to claim 1, characterized by comprising the following steps: before preparing the modified probe (14), the gold-plated probe (6) needs to be placed in a plasma cleaning machine for 10 minutes and soaked in an ethanol solution for 5 minutes to remove pollutants.

6. The method for screening the molecular functional groups of the coal slime flotation collector according to claim 1, characterized by comprising the following steps: after a modified probe (14) with different flotation collector molecular functional groups deposited on the surface is formed on the gold-plated probe (6), the modified probe (14) needs to be sequentially soaked in ethanol and ultrapure water for 10 minutes, and then is placed into a vacuum drying oven to be dried for later use.

7. The method for screening the molecular functional groups of the coal slime flotation collector according to claim 1, characterized by comprising the following steps: the coal sample (9) is cut into a flat structure and the surface is polished smooth and then cleaned to ensure no pollution.

8. The method for screening the molecular functional groups of the coal slime flotation collector according to claim 1, characterized by comprising the following steps: before the modified probe (14) is inserted, the deflection sensitivity of a probe cantilever of the modified probe (14) needs to be measured, the actual elastic coefficient of the probe cantilever is calculated, the elastic coefficient correction is completed, and the accuracy of force test data is ensured; after the correction is completed, the needle insertion of the modified probe (14) is controlled to be close to and far away from the surface of the coal sample (9) through piezoelectric ceramics to obtain force information, the needle insertion and needle withdrawal of each modified probe (14) are repeated at different positions of the coal sample (9) respectively, so that the adhesive force of the modified probe (14) and the different positions of the coal sample (9) is obtained, the average number of the adhesive force collected at the different positions is taken, and the representativeness and the accuracy of a force curve test are guaranteed.

9. The method for screening the molecular functional groups of the coal slime flotation collector according to claim 7, wherein the method comprises the following steps: carrying out normal distribution fitting on the test result of the needle withdrawal curve force, and determining the adhesive force between the modified probe (14) and the coal sample (9); the EDLVO theory was used to fit the needle insertion force curve and determine the components of van der waals, electrostatic and hydrophobic forces in the interaction forces.

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