CN111426641A - Method for detecting density distribution state of nano material - Google Patents
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Abstract
The invention discloses a method for detecting the density distribution state of a nano material. The detection method comprises the following steps: providing a detection container; injecting a density gradient solution into the detection container; dispersing the nano material to be detected in the density gradient solution; irradiating the density gradient solution dispersed with the nano material to be detected by using a detection light beam, and performing primary image acquisition on the whole formed by the detection container and the density gradient solution dispersed with the nano material to be detected to obtain a primary image acquisition result; and obtaining the density distribution state of the nano material to be detected according to the first image acquisition result. According to the method for detecting the density distribution state of the nano material, provided by the embodiment of the invention, the nano material to be detected is separated by using the density gradient solution, and the detection light beam is adopted to irradiate the density gradient solution which is formed by the detection container and is dispersed with the nano material to be detected, so that the operation is simple and convenient when the density distribution of the nano material to be detected is obtained, and the method can be applied to high-flux commercial detection application.
Description
Technical Field
The embodiment of the invention relates to the technical field of nano material detection, in particular to a method for detecting the density distribution state of a nano material.
Background
Since the concept of nanomaterials has come about, various new nanomaterials have emerged, and nanomaterials are well known and widely used in various fields today.
Some classical two-dimensional nanomaterials, such as graphene, have been commercially produced in large quantities. However, the quality of commercial nanomaterials on the market is not uniform, and the existing characterization methods cannot realize efficient and convenient detection of nanomaterials in large quantities.
Disclosure of Invention
The invention provides a method for detecting the density distribution state of a nano material, which is used for realizing the detection of the density of the nano material in a large batch and high efficiency.
The embodiment of the invention provides a method for detecting the density distribution state of a nano material, which comprises the following steps:
providing a detection container;
injecting a density gradient solution into the detection vessel; the density gradient solution comprises a plurality of density gradient solution layers which are arranged in a stacked mode, and solutes of the density gradient solution layers are the same; the solute concentration of each density gradient solution layer is increased in sequence along the direction from the free liquid level of the density gradient solution to the bottom surface of the detection container;
dispersing the nano material to be detected in the density gradient solution; the density of the most dense part in the nano material to be detected is rho 1, the density of the density gradient solution layer with the largest solute concentration in the density gradient solution is rho 2, the density of the density gradient solution layer with the smallest solute concentration in the density gradient solution is rho 3, and rho 3 is more than rho 1 and less than rho 2;
irradiating the density gradient solution dispersed with the nano material to be detected by using a detection light beam, and performing first image acquisition on the whole formed by the detection container and the density gradient solution dispersed with the nano material to be detected to obtain a first image acquisition result M1;
and obtaining the density distribution state of the nano material to be detected according to the first image acquisition result.
Further, the step of irradiating the density gradient solution dispersed with the nano material to be detected with the detection light beam, and performing a first image acquisition on the whole body formed by the detection container and the density gradient solution dispersed with the nano material to be detected to obtain a first image acquisition result M1 is performed in a darkroom.
Further, the obtaining the density distribution state of the to-be-detected nano-material according to the first image acquisition result includes:
removing noise information in the first image acquisition result to obtain a first image processing result;
and obtaining the density distribution state of the nano material to be detected based on the first image processing result.
Further, before the step of dispersing the nano material to be detected in the density gradient solution, the method comprises the following steps:
under the condition of no illumination, carrying out secondary image acquisition on the whole body formed by the detection container and the density gradient solution to obtain a secondary image acquisition result M2;
irradiating the density gradient solution by using the detection light beam, and carrying out third image acquisition on the whole body formed by the detection container and the density gradient solution to obtain a third image acquisition result M3;
the removing of the noise information in the first image acquisition result to obtain a first image processing result includes:
according to M4 ═ M1- (M3-M2) -M2, M4 is taken as the first image processing result.
Further, obtaining the density distribution state of the to-be-detected nano-material based on the first image processing result includes:
extracting regional image information corresponding to each density gradient solution layer from the first image processing result;
obtaining the change relation of the gray value along with the concentration of the density gradient solution layer according to the regional image information corresponding to the density gradient solution;
obtaining the change relation of the absorbance along with the concentration of the density gradient solution layer based on the change relation of the gray value along with the concentration of the density gradient solution layer;
and obtaining the density distribution state of the nano material to be detected based on the variation relation of the absorbance along with the concentration of the density gradient solution layer.
Further, the irradiating the density gradient solution dispersed with the nano material to be detected with the detection light beam, and performing a first image acquisition on an entire body formed by the detection container and the density gradient solution dispersed with the nano material to be detected to obtain a first image acquisition result M1 includes:
irradiating the density gradient solution dispersed with the nano material to be detected by using the detection light beam, and performing first image acquisition on the whole formed by the detection container and the density gradient solution dispersed with the nano material to be detected by using a continuous shooting method to obtain a first image acquisition result M1.
Further, the detection container is a transparent centrifuge tube or cuvette.
Further, the material of the detection container comprises quartz, polystyrene, polymethyl methacrylate or optical glass.
Further, the solute of the density gradient solution is cesium chloride or cesium fluoride.
Further, the detection light beam is generated by a laser generator.
According to the method for detecting the density distribution state of the nano material, provided by the embodiment of the invention, the nano material to be detected is separated by using the density gradient solution, the detection light beam is adopted to irradiate the whole body formed by the detection container and the density gradient solution dispersing the nano material to be detected, so that the first image acquisition result is acquired and obtained, and the density distribution state of the nano material to be detected is obtained according to the first image acquisition result.
Drawings
FIG. 1 is a flow chart of a method for detecting a density distribution state of a nanomaterial, provided by an embodiment of the invention;
FIG. 2 is a flow chart of another method for detecting the density distribution of the nanomaterial provided by the embodiment of the invention;
FIG. 3 is a flow chart of detecting a noise signal according to an embodiment of the present invention;
FIG. 4 is a flow chart of another method for detecting the density distribution of the nanomaterial provided by the embodiment of the invention;
FIG. 5 is a pictorial view of a cesium fluoride solution and a detection vessel containing graphene and not reaching sedimentation equilibrium provided in an embodiment of the present invention;
fig. 6 is a pictorial view of a cesium fluoride solution and a detection vessel containing graphene after settling equilibrium as provided by an embodiment of the present invention;
fig. 7 is a schematic diagram of a distribution of gray values of graphene provided in an embodiment of the present invention;
fig. 8 is a schematic diagram of the distribution of optical density of graphene provided by an embodiment of the present invention;
fig. 9 is a schematic distribution diagram of graphene with different densities provided by an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
The invention has the general conception that the density distribution of the nano material is processed by utilizing the principle of a density gradient sedimentation method, the density gradient sedimentation separation method is a method for separating nano particles with different densities by using a stepped or continuous density gradient liquid according to different sedimentation rates, and the layering of the nano material in different density gradients can be realized by utilizing the method. The density gradient sedimentation method is a special density gradient centrifugal separation technology and has the advantages of simple and convenient operation and the like.
After the nano material is layered by using a density gradient sedimentation method, the physicochemical property of the nano material is analyzed by using an optical detection technology. Specifically, the optical measurement technology is used for measuring the nano material subjected to density gradient separation and determining the density distribution of the nano material by analyzing the gray scale of an image based on an optical imaging method.
Based on the principle, the embodiment of the invention provides a method for detecting the density distribution state of a nano material.
Fig. 1 is a flowchart of a method for detecting a density distribution state of a nanomaterial, according to an embodiment of the present invention. Specifically, referring to fig. 1, the detection method includes:
and step 10, providing a detection container.
Specifically, the detection container is used for containing a density gradient solution and the nano material to be detected dispersed in the density gradient solution.
Specifically, the solutes in the plurality of density gradient solution layers in the density gradient solution are the same, but the concentrations of the solutes are different, thereby forming a concentration gradient, and when the nanomaterial to be detected is placed in the density gradient solution, the nanomaterial to be detected having different densities can be distributed in the different density gradient solution layers. In addition, in a case where necessary, the uppermost density gradient solution layer in the density gradient solution may be pure water, that is, the density gradient solution layer forming the free liquid surface may not contain a solute. Generally, the density of the solute is often greater than that of pure water, the density of the solution containing the solute is also greater than that of the pure water, and by arranging the density gradient solution layer not including the solute, the density range of the density gradient solution can be wider, and the density gradient solution can detect more nano materials to be detected with different densities.
Specifically, when the nano material to be detected is dispersed in the density gradient solution, the nano material to be detected can be placed on the free liquid surface lightly; because the density gradient solution layers in the density gradient solution can be rapidly mixed into a single solution with uniform density when the density gradient solution layers are violently vibrated, the light-release standard is to prevent the density gradient solution layers from being mixed due to vibration when the nano material to be detected is placed. It should be understood that, in the experiment, the lighter the operation when the nanomaterial to be detected is placed, the less the influence is exerted on the plurality of density gradient solution layers, and the more the plurality of density gradient solution layers can maintain the layered state for a relatively long time.
The embodiment adopts the principle of gravity to settle and separate the nano material to be detected; in general, the same kind of nanomaterial includes a plurality of components with different densities, the sedimentation rates of the components with different densities in the density gradient solution are different, if the density of the detection nanomaterial is higher, the sedimentation rate in the density gradient solution is faster, and finally, the position in the density gradient solution is relatively closer to the bottom of the detection container. Since the nano material to be detected cannot reach the density gradient solution layer with the density higher than that of the nano material, the nano material to be detected finally stops on the upper layer of the density gradient solution layer with the density slightly higher than that of the nano material. And after a period of stabilization, the nano-materials to be detected with various densities settle and stabilize in the specific density gradient solution layer. If the density of a large amount of nano materials to be detected is greater than that of the density gradient solution layer with the maximum solute concentration in the density gradient solution, a large amount of nano materials to be detected are deposited in the density gradient solution layer with the maximum solute density, and thus, an accurate detection result is difficult to obtain. Therefore, in order to ensure that each density gradient solution layer contains a certain amount of nano-material to be detected, the density of the density gradient solution layer with the minimum solute concentration in the density gradient solution can be close to but slightly smaller than the component with the minimum density in the nano-material to be detected, and meanwhile, the density of the density gradient solution layer with the minimum solute concentration in the density gradient solution is close to but slightly larger than the component with the maximum density in the nano-material to be detected. Before detection, the density distribution of the nano material to be detected can be estimated through an estimation and judgment method, and the density of each density gradient solution layer in the density gradient solution is further determined.
And step 40, irradiating the density gradient solution dispersed with the nano material to be detected by using the detection light beam, and performing first image acquisition on the whole formed by the detection container and the density gradient solution dispersed with the nano material to be detected to obtain a first image acquisition result M1.
Specifically, since the nanomaterial to be detected interacts with light, such as light absorption, the more the nanomaterial to be detected in the density gradient solution layer, the stronger the absorption of light by the nanomaterial to be detected, and the less light that passes through the density gradient solution layer. In order to obtain the distribution of the detection nano-materials in each density gradient solution layer, a first image acquisition result M1 can be obtained according to the acquired first image acquisition.
And step 50, obtaining the density distribution state of the nano material to be detected according to the first image acquisition result.
Specifically, according to the first image acquisition result, the light intensity penetrating through each density gradient solution layer can be known, so that the amount of the nano material to be detected in each density gradient solution layer is determined, and the density distribution of the nano material to be detected is determined.
The method for detecting the density distribution state of the nanomaterial provided by this embodiment separates the nanomaterial to be detected by using the density gradient solution, irradiates the whole body formed by the detection container and the density gradient solution dispersing the nanomaterial to be detected with the detection light beam, further collects and obtains the first image collection result, and obtains the density distribution state of the nanomaterial to be detected according to the first image collection result.
Optionally, the step of irradiating the density gradient solution dispersed with the nano material to be detected with the detection light beam, and performing a first image acquisition on the whole body formed by the detection container and the density gradient solution dispersed with the nano material to be detected to obtain a first image acquisition result M1 is performed in a dark room.
In particular, because only the detection light beam exists in the darkroom, the interference of other light sources on the detection result can be avoided to the greatest extent possible. A dark room, as used herein, is understood to mean that no other light beam is present than the detection light beam. It should be noted that, when the detection beam is used to irradiate the density gradient solution dispersed with the nano-material to be detected, the propagation direction of the detection beam may be parallel to the free liquid level of the density gradient solution, and in order to detect the nano-material to be detected in each density gradient solution layer, the detection beam may be irradiated to each detection solution layer.
Fig. 2 is a flowchart of another method for detecting a density distribution state of a nanomaterial according to an embodiment of the present invention. Optionally, referring to fig. 2, step 50, obtaining a density distribution state of the to-be-detected nanomaterial according to the first image acquisition result, including;
and 51, removing noise information in the first image acquisition result to obtain a first image processing result.
And step 52, obtaining the density distribution state of the nano material to be detected based on the first image processing result.
Specifically, certain noise information often exists in the first image acquisition result, so that in order to obtain a more accurate detection result, the noise information in the first image acquisition result can be removed, a first image processing result can be obtained, and a more accurate density distribution state of the nano material to be detected can be obtained according to the first image processing result.
Fig. 3 is a flow chart of detecting a noise signal according to an embodiment of the present invention. Alternatively, referring to fig. 3, before dispersing the nano-material to be detected in the density gradient solution in step 30, the method includes:
and step 31, carrying out second image acquisition on the whole body formed by the detection container and the density gradient solution under the condition of no illumination to obtain a second image acquisition result M2.
Specifically, a camera can be generally used for image acquisition, and due to the limitation of the current camera technical level, when the camera acquires an image, the camera itself often has a certain dark current, which has a certain interference on the final detection result, so that an interference signal generated by the camera itself can be detected in a dark room without light, and when a noise signal is removed, the signal can be removed.
And step 32, irradiating the density gradient solution by using the detection light beam, and performing third image acquisition on the whole body formed by the detection container and the density gradient solution to obtain a third image acquisition result M3.
Specifically, considering that the detection container and the density gradient solution also interact with the detection beam to some extent, when the noise signal is removed, the interference caused by the detection container and the density gradient solution can also be removed.
Optionally, in step 51, removing noise information in the first image acquisition result to obtain a first image processing result, including: according to M4 ═ M1- (M3-M2) -M2, M4 is taken as the first image processing result.
Since the camera acquires image information under various conditions such as light and no light, interference signals due to the camera itself are present, and thus the third image acquisition result M3 actually includes two major interference signals, one from the camera itself and the other from the detection container and the density gradient solution. M3-M2 in the above formula represents the interference signal that is solely caused by the detection vessel and the density gradient solution.
Fig. 4 is a flowchart of another method for detecting a density distribution state of a nanomaterial, according to an embodiment of the present invention. Optionally, referring to fig. 4, step 52, obtaining a density distribution state of the to-be-detected nanomaterial based on the first image processing result includes:
and step 521, extracting the regional image information corresponding to each density gradient solution layer from the first image processing result.
Specifically, when the detection light beam penetrates through each layer of density gradient solution in a direction parallel to the free liquid level, since the number of the nano materials to be detected in each layer of density gradient solution layer is different, the detection result corresponding to each layer of density gradient solution layer in the first image processing result is different, and therefore, before the density distribution of the nano materials to be detected is determined, the regional image information corresponding to each density gradient solution layer can be extracted first.
And 522, obtaining the change relation of the gray value along with the concentration of the density gradient solution layer according to the regional image information corresponding to the density gradient solution.
Specifically, in general, in order to improve the detection accuracy, a density gradient solution and a detection container which absorb light weakly are generally used; since the density-gradient solution absorbs light very weakly, the difference in absorption of the density-gradient solution layers of different solute concentrations is essentially negligible. Because the density, the quantity and the like of the nano materials to be detected in each density gradient solution layer are different, the light intensity of the same detection light beam after penetrating through the density gradient solution layers containing the nano materials to be detected with different concentrations and densities is different, and the detection light beam is reflected in the first image processing result, and can show that the corresponding gray values of different density gradient solution layers are different, so that the difference of the gray values can be used for reflecting the difference of the density and the concentration of the nano materials to be detected in different density gradient solution layers.
Specifically, the absorption of the nano material to be detected to light is the reason for the difference of the gray value, so that the change relation of the absorbance along with the concentration of the density gradient solution layer can be judged according to the change relation of the gray value along with the concentration of the density gradient solution layer.
And 524, obtaining the density distribution state of the nano material to be detected based on the variation relation of the absorbance along with the concentration of the density gradient solution layer.
Specifically, when the density gradient solution layer contains the nano material to be detected, the light absorption of the density gradient solution layer is mainly determined by the nano material to be detected in the density gradient solution layer, so that the density distribution state of the nano material to be detected can be obtained based on the change relationship of the absorbance along with the concentration of the density gradient solution layer.
Optionally, irradiating the density gradient solution dispersed with the nano material to be detected with a detection light beam, and performing a first image acquisition on an entire body formed by the detection container and the density gradient solution dispersed with the nano material to be detected to obtain a first image acquisition result M1, including: irradiating the density gradient solution dispersed with the nano material to be detected by using a detection light beam, and performing first image acquisition on the whole formed by the detection container and the density gradient solution dispersed with the nano material to be detected by using a continuous shooting method to obtain a first image acquisition result M1.
Specifically, taking the two-dimensional nano material to be detected as an example, which is usually a sheet-like structure, the relationship between the two-dimensional nano material to be detected and the detection light beam may be different at different times under the influence of molecular motion in the density gradient solution. For example, at a certain moment, most of the two-dimensional planes of the nano-materials to be detected may be parallel to the detection beam, and most of the detection beam may transmit the density gradient solution, but at another moment, most of the two-dimensional planes of the nano-materials to be detected may be perpendicular to the detection beam, and most of the detection beam may not transmit the density gradient solution. In order to avoid the phenomenon, a continuous shooting method can be adopted, and the interference caused by accidental factors to the detection result can be avoided by processing a plurality of shooting results and averaging the shooting results.
Optionally, the detection vessel is a transparent centrifuge tube or cuvette.
Specifically, centrifuging tube and cell all have transparent, frivolous and advantage such as with low costs, are good detection container. Further, it should be understood that the detection containers herein include, but are not limited to, the centrifuge tubes and cuvettes described above.
Optionally, the material of the detection vessel comprises quartz, polystyrene, polymethylmethacrylate or optical glass.
It should be noted that, when the container is detected, the interaction between the detection container and the light should be ensured to be weak, and when this condition is satisfied, the present embodiment does not specifically limit the selection of the material of the detection container.
Optionally, the solute of the density gradient solution is cesium chloride or cesium fluoride.
Specifically, in order to obtain accurate and reliable detection results, solutes with weak light absorption can be selected to prepare a density gradient solution. In general, the absorption of visible light by cesium chloride and cesium fluoride solutions is weak, so that the detection light beams can be ensured to be transmitted. Further, cesium chloride and cesium fluoride have a relatively high solubility in water, and can be arranged in a density gradient solution layer having a plurality of concentration gradients. Illustratively, at 291.15K, the solubility of cesium fluoride in water can reach 367g, and cesium fluoride as a medium for preparing a density gradient can prepare a wider density range than other solutes, and is suitable for more inorganic nano materials to form a suspension dispersion system in a solution. In addition, aqueous solutions of cesium fluoride are stable and inactive against most inorganic materials. Also, the solubility of cesium fluoride in methanol was high, reaching 191g at 288.15K. It should be understood that other solute configuration density gradient solutions may be selected under the conditions of weak action with light, high solubility, stable water solution property, and the like, and the embodiment is not particularly limited in this respect.
Optionally, the detection light beam is generated by a laser generator.
Optionally, the laser generator can generate laser beams, and the laser beams have the advantages of high laser brightness, high directivity, high monochromaticity, high coherence and the like, and can be widely applied to the detection of nano materials. In addition, if the nano material to be detected is graphene, cesium fluoride can be selected as a solute of the density gradient solution, and visible light with the wavelength of 633nm is selected as a detection light beam, so that the absorption of the nano material to be detected on the detection light beam is reduced to the greatest extent.
Illustratively, to help the reader understand the technical solution of the present invention, this embodiment further provides a method for detecting a graphene nanomaterial by using a laser beam with a wavelength of 633nm and a cesium fluoride solution, where the detection method is detailed as follows:
firstly, establishing a basic model, specifically as follows:
preparing cesium fluoride aqueous solutions with different mass fractions as density gradient solutions for standby, wherein the density gradient prepared by using the cesium fluoride aqueous solutions can range from 1.00g/ml to 2.70g/ml by adjusting the mass fractions (cesium fluoride concentrations). In the cuvette, gradient liquids with different densities are prepared into step (namely discontinuous) density gradient liquids sequentially from bottom to top according to the density from large to small by adopting an upper paving method. After the density gradient solution is formed, the graphene to be detected may be placed in a cuvette. Fig. 5 is a schematic diagram of a cesium fluoride solution and a detection container provided in an embodiment of the present invention when graphene is just put in but not reaching a sedimentation equilibrium, and fig. 6 is a schematic diagram of a cesium fluoride solution and a detection container provided in an embodiment of the present invention and containing graphene after sedimentation equilibrium. It should be noted that the sedimentation equilibrium is understood that, after the graphene is deposited in the cesium fluoride solution for a certain period of time, graphene with different densities is distributed in the cesium fluoride solution layer with corresponding concentration, and at this time, the solution of cesium fluoride containing graphene is in a relatively stable state.
When the nano material reaches the sedimentation equilibrium in a certain layer of density gradient liquid, a stable and uniform state can be formed. Light flux phi transmitted through the cuvette without taking into account scattering of the materialt＝Φ0-ΦaWherein phi is0Is the luminous flux of the detection beam before incidence on the cuvette, and phiaIs the light flux absorbed by the graphene nanomaterial. Detecting the light transmission of the light beam through the sample as
It follows that the light flux transmitted through the cuvette is related to the absorption capacity of the material for light.
According to the law of lambert beer,
wherein A isiShowing the absorbance of the graphene in the gradient liquid of the ith layer,idenotes the extinction coefficient of graphene, ciAnd (3) the concentration of graphene in the gradient liquid of the ith layer is shown, and the subscript i is a positive integer.
After a camera is used for collecting detection light beams and transmitting cesium fluoride solution containing graphene, and software such as ImageJ and the like is used, a gray level image of the graphene can be obtained, wherein the gray level value meets the following requirements:
wherein I represents a current obtained by photoelectric conversion, ImCurrent in light saturation of photosensitive element, P0The light power irradiated on the photosensitive element when the photosensitive element is in light saturation; symbol [ 2 ]]As a rounding function, e.g. [3.5 ]]3; 256 is related to the length of the data storage byte, and in a general state, the range of the gray scale value can be 0-255, and 256 numbers are provided.
The above formula is arranged to obtain the formula,
in combination with the formula(s),
then, a change curve of material concentration-Distance (c-Distance) can be obtained according to a ═ k · α · c and a ═ lg256-lgY, and what we used is a density gradient liquid, and when the density gradient liquid is within a certain Distance, namely the same gradient, the material concentration is consistent, so that the distribution of the material content in the vertical Distance, namely the density gradient distribution of the material, can be obtained.
It should also be noted that the gray value is effectively the maximum value of the material concentration measured
I.e. in response to current
When I takes 0, the above formula has no practical significance, and therefore, an appropriate method can be selected to solve this problem.
In addition, in consideration of the error influence of the optical system and the photoelectric signal conversion transmission, correction terms are introduced, wherein A is k (α c + B), wherein A represents the absorbance obtained on the basis of the gray scale value, namely the OD value, k represents the proportionality coefficient, α represents the absorption coefficient of graphene, c represents the gradient of the cesium fluoride solution, and B is an error correction term.
Now, the basic model is established, and the following discussion of the image processing and analysis method is performed.
And (5) analyzing and processing data.
For image continuous shooting averaging, i.e. statistical averaging of absorbance based on gray scale values, then
Wherein the content of the first and second substances,
the statistical average of the OD values of the density gradient liquid images taken n times in the absence of the sample and in the presence of the sample respectively, wherein the value of n can be 20-30 times.
In the image information processing stage, optical information integration is carried out on each continuous shooting image through corresponding software, and the integrated image information of the density gradient liquid without the sample is called M0The density gradient liquid image information in the presence of a sample is called M1The final image information is called M'. According to the formula M ═ M1-M0And processing the image information to obtain a final image information result.
Formula M ═ M1-M0Is embodied as
Fig. 7 is a schematic diagram of a distribution of gray scale values of graphene provided by an embodiment of the present invention, and fig. 8 is a schematic diagram of a distribution of optical density of graphene provided by an embodiment of the present invention. Referring to fig. 7 and 8, an abscissa in fig. 7 represents a density of graphene, an ordinate represents a gray level value of the detected nanomaterial obtained by detection, an abscissa in fig. 8 represents a density of graphene, and an ordinate represents an optical density of the detected nanomaterial obtained by detection. It should be noted that the optical density here should be understood that the larger the absorption density is, the less the light beam is transmitted, and the darker the image is, that is, the more the detection light beam is absorbed by the graphene, the more graphene is in the density gradient solution. Therefore, comparing fig. 7 and 8, it is clear that the light density in fig. 8 is smaller at a place where the gradation value is larger in fig. 7. As can be seen from FIG. 8, the density was 1.3g/cm3The amount of graphene on the left and right is the largest.
Fig. 9 is a schematic distribution diagram of graphene with different densities provided by an embodiment of the present invention. Optionally, referring to fig. 9, after the density of the graphene is obtained by using the method for detecting a density distribution state of a nanomaterial provided in this embodiment, a detection result may be drawn into a histogram, so that a clearer and more clear detection result may be obtained. As can be seen from FIG. 9, the density of 72.73% graphene is 1.3g/cm3Left and right.
The embodiment provides a new measuring means for the commercial nano material detection method, and has important significance for quality detection of commercial nano materials, quantitative separation and purification of nano materials and the like.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (10)
1. A method for detecting the density distribution state of a nano material is characterized by comprising the following steps:
providing a detection container;
injecting a density gradient solution into the detection vessel; the density gradient solution comprises a plurality of density gradient solution layers which are arranged in a stacked mode, and solutes of the density gradient solution layers are the same; the solute concentration of each density gradient solution layer is increased in sequence along the direction from the free liquid level of the density gradient solution to the bottom surface of the detection container;
dispersing the nano material to be detected in the density gradient solution; the density of the most dense part in the nano material to be detected is rho 1, the density of the density gradient solution layer with the largest solute concentration in the density gradient solution is rho 2, the density of the density gradient solution layer with the smallest solute concentration in the density gradient solution is rho 3, and rho 3 is more than rho 1 and less than rho 2;
irradiating the density gradient solution dispersed with the nano material to be detected by using a detection light beam, and performing first image acquisition on the whole formed by the detection container and the density gradient solution dispersed with the nano material to be detected to obtain a first image acquisition result M1;
and obtaining the density distribution state of the nano material to be detected according to the first image acquisition result.
2. The method for detecting the density distribution state of nanomaterials of claim 1,
the step of irradiating the density gradient solution dispersed with the nano material to be detected with a detection light beam, and performing a first image acquisition on the whole formed by the detection container and the density gradient solution dispersed with the nano material to be detected to obtain a first image acquisition result M1 is performed in a darkroom.
3. The method for detecting the density distribution state of the nanomaterial according to claim 1, wherein the obtaining the density distribution state of the nanomaterial to be detected according to the first image acquisition result comprises:
removing noise information in the first image acquisition result to obtain a first image processing result;
and obtaining the density distribution state of the nano material to be detected based on the first image processing result.
4. The method for detecting the density distribution state of nanomaterials of claim 3,
before the step of dispersing the nano material to be detected in the density gradient solution, the method comprises the following steps:
under the condition of no illumination, carrying out secondary image acquisition on the whole body formed by the detection container and the density gradient solution to obtain a secondary image acquisition result M2;
irradiating the density gradient solution by using the detection light beam, and carrying out third image acquisition on the whole body formed by the detection container and the density gradient solution to obtain a third image acquisition result M3;
the removing of the noise information in the first image acquisition result to obtain a first image processing result includes:
according to M4 ═ M1- (M3-M2) -M2, M4 is taken as the first image processing result.
5. The method for detecting the density distribution state of nanomaterials of claim 3,
obtaining the density distribution state of the nano material to be detected based on the first image processing result, wherein the obtaining of the density distribution state comprises the following steps:
extracting regional image information corresponding to each density gradient solution layer from the first image processing result;
obtaining the change relation of the gray value along with the concentration of the density gradient solution layer according to the regional image information corresponding to the density gradient solution;
obtaining the change relation of the absorbance along with the concentration of the density gradient solution layer based on the change relation of the gray value along with the concentration of the density gradient solution layer;
and obtaining the density distribution state of the nano material to be detected based on the variation relation of the absorbance along with the concentration of the density gradient solution layer.
6. The method for detecting the density distribution state of nanomaterials of claim 1,
the irradiating the density gradient solution dispersed with the nano material to be detected by using the detection light beam, and performing a first image acquisition on the whole formed by the detection container and the density gradient solution dispersed with the nano material to be detected to obtain a first image acquisition result M1, including:
irradiating the density gradient solution dispersed with the nano material to be detected by using the detection light beam, and performing first image acquisition on the whole formed by the detection container and the density gradient solution dispersed with the nano material to be detected by using a continuous shooting method to obtain a first image acquisition result M1.
7. The method for detecting the density distribution state of nanomaterials of claim 1,
the detection container is a transparent centrifuge tube or cuvette.
8. The method for detecting the density distribution state of nanomaterials of claim 7, wherein the material of the detection container comprises quartz, polystyrene, polymethyl methacrylate, or optical glass.
9. The method for detecting the density distribution state of the nanomaterial according to claim 1, wherein the solute of the density gradient solution is cesium chloride or cesium fluoride.
10. The method as claimed in claim 1, wherein the detection beam is generated by a laser generator.
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