Infrared spectroscopy-based method for detecting the grafting rate of nano-desorption permeabilizers

Abstract

This application relates to the field of percolator grafting rate detection technology, specifically to a method for detecting the grafting rate of nano-desaturated percolators based on infrared spectroscopy. The method includes: preparing multiple percolator samples in batches; dividing each batch of percolator samples into multiple sub-samples of equal mass; washing and drying each sub-sample a different number of times; obtaining the baseline of overlapping peaks in the infrared spectral data; obtaining the true grafting rate of each batch of percolator samples; constructing a grafting rate correction model based on the proportion of the characteristic peak area corresponding to the Si-O-C bond of the silane coupling agent in the overlapping peak area of ​​each percolator sample; and solving the grafting rate correction model using the true grafting rate, observed grafting rate, and infrared spectral data of all batches of percolator samples, thereby calculating the true grafting rate of the percolator sample to be detected. This application improves the accuracy of grafting rate detection by correcting the grafting rate obtained from thermogravimetric analysis using infrared spectral data characteristics.

Description

Technical Field

[0001] This application relates to the field of percolator grafting rate detection technology, specifically to a method for detecting the grafting rate of nano-desaturated percolators based on infrared spectroscopy. Background Technology

[0002] Carbon-based and silicon-based nanoparticles possess characteristics such as small particle size, easy penetration into the micropores and throats of rocks, high specific surface area and chemical activity, and good stability under complex reservoir conditions. Due to the large number of hydroxyl functional groups on their surface, they exhibit strong hydrophilic properties and readily aggregate under the influence of hydrogen bonds, making them prone to agglomeration during dispersion. Therefore, carbon-based and silicon-based percolators prepared using carbon-based and silicon-based nanoparticles have become commonly used oil displacement agents in oilfields.

[0003] Whether the prepared silicon-based or carbon-based percolator has been successfully grafted needs to be determined through certain characterization methods, the most important of which is the quantification of the grafting rate. Conventional detection methods use thermogravimetric analysis (TGA) to quantify the grafting rate by measuring the percentage of mass loss. However, in the actual preparation process of the percolator, there may be additional residues or intermediate products, leading to additional mass loss during TGA and thus causing deviations in the grafting rate measurement results. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a method for detecting the grafting rate of nano-desaturated permeabilizers based on infrared spectroscopy, thereby resolving the existing issues.

[0005] The method for detecting the grafting rate of nano-despairing permeabilizer based on infrared spectroscopy in this application adopts the following technical solution:

[0006] One embodiment of this application provides a method for detecting the grafting rate of nano-despairing permeabilizers based on infrared spectroscopy. The method includes the following steps:

[0007] For any type of percolator, such as silicon-based or carbon-based percolators, multiple percolator samples were prepared in batches, and the infrared spectral data and grafting rate of each percolator sample were obtained. Each batch of percolator samples was divided into multiple sub-samples of equal mass, and each sub-sample was washed and dried a different number of times. The infrared spectral data and grafting rate of each sub-sample were obtained.

[0008] The overlapping peaks in the infrared spectral data of each subsample are extracted, and the baseline of the overlapping peaks is obtained by utilizing the correlation between the overlapping peak area of ​​all subsamples under different baselines and the observed grafting rate.

[0009] Based on the variation characteristics between the number of washing and drying cycles and the observed grafting rate of each batch of subsamples, the true grafting rate of each batch of percolator samples is obtained. Based on the proportion of the characteristic peak area corresponding to the Si-OC bond of the silane coupling agent in the overlapping peak area corresponding to the overlapping peak baseline of each percolator sample, a grafting rate correction model is constructed. The grafting rate correction model is solved by using the true grafting rate, observed grafting rate, overlapping peak area, and infrared absorbance at the peak wavenumber of the Si-OC bond of the silane coupling agent in the infrared spectral data of all batches of percolator samples.

[0010] Using the solved grafting rate correction model, along with the observed grafting rate and infrared spectral data of the absorbent sample to be tested, the true grafting rate of the absorbent sample to be tested is calculated.

[0011] Preferably, silicon-based absorbents are absorbents made using nano-silica as a framework, while carbon-based absorbents are absorbents made using graphene quantum dots as a framework.

[0012] Preferably, the observed grafting rate refers to the grafting rate measured using thermogravimetric analysis.

[0013] Preferably, the method for extracting overlapping peaks in the infrared spectral data of each subsample is as follows:

[0014] If the subsample is a silicon-based penetrant, its overlapping peak refers to the peak formed by the superposition of the characteristic peaks of Si-O-Si bonds, Si-OC bonds and COC bonds in its infrared spectral data;

[0015] If the subsample is a carbon-based percolator, its overlapping peak refers to the peak formed by the superposition of the characteristic peaks of COC bond, Si-O bond and Si-OC bond in its infrared spectral data.

[0016] As a preferred method, the method for calculating the overlapping peak area in the infrared spectral data of each sub-sample is as follows: In the formula, This represents the overlapping peak area of ​​the infrared spectral data of the i-th subsample. The baseline representing the overlapping peaks. This represents the infrared spectral curve corresponding to the overlapping peak of the i-th subsample. , denoted as the wavenumber corresponding to the cross-start point and the cross-end point of the overlapping peak baseline and the overlapping peak of the i-th subsample, respectively.

[0017] Preferably, the process for obtaining the baseline of the overlapping peaks is as follows:

[0018] Within the preset baseline range, each baseline is traversed with a preset step size, and each is substituted into the overlapping peak area calculation formula to calculate the overlapping peak area of ​​each subsample under each baseline.

[0019] Using the overlapping peak area and observed grafting rate of all sub-samples of all batches of percolating agent samples under a single baseline as input, curve fitting is performed using the least squares method, where the observed grafting rate is used as the dependent variable and the overlapping peak area is used as the independent variable, to obtain the fitting function and fitting error corresponding to a single baseline.

[0020] Obtain the fitting function and fitting error corresponding to all baselines, and denote the baseline corresponding to the minimum fitting error as the baseline of the overlapping peak.

[0021] Preferably, the true grafting rate of each batch of percolator samples refers to the observed grafting rate when the overlapping peak area and the observed grafting rate no longer change with the increase of the number of washing and drying cycles for each batch of sub-samples.

[0022] Preferably, the grafting rate correction model is constructed as follows: In the formula, This represents the true grafting rate of the j-th batch of percolator samples; This indicates that in the infrared spectral data of the j-th batch of percolator sample... The infrared absorbance at the wavenumber; The peak wavenumber of the Si-OC bond in the silane coupling agent; Represents the fitting coefficient; The baseline representing the overlapping peaks; This represents the overlapping peak area of ​​the j-th batch of percolating agent samples; This represents the observed grafting rate of the j-th batch of percolator samples.

[0023] Preferably, the solution process for the grafting rate correction model is as follows:

[0024] The true grafting rate, overlapping peak area, and infrared spectral data corresponding to all batches of percolator samples were analyzed. The infrared spectral absorbance at the corresponding wavenumber and the observed grafting rate are used as inputs, with the actual grafting rate as the dependent variable, and the overlapping peak area and the infrared spectral data as inputs. The infrared spectral absorbance at the wavenumber and the observed grafting rate are used as independent variables. After being substituted into the grafting rate correction model, the least squares method is used to perform linear regression fitting to solve for the specific value of the fitting coefficient k, thus obtaining the solved grafting rate correction model.

[0025] Preferably, the method for calculating the true grafting rate of the penetrant sample to be tested is as follows: The overlapping peak area and infrared spectral data of the penetrant sample to be tested are compared and analyzed. The infrared absorbance at the wavenumber and the observed grafting rate are substituted into the solved grafting rate correction model to obtain the true grafting rate of the penetrant sample to be tested.

[0026] This application has at least the following beneficial effects:

[0027] This application addresses the issue that traditional thermogravimetric analysis (TGA) methods for detecting grafting rates in percolators directly quantify the results based on TGA, neglecting the contribution of residual silane coupling agents to the pyrolysis weight loss during the actual process. This leads to an overestimation of the grafting rate. Therefore, this application first analyzes the correlation between the overlapping peak area and the observed grafting rate in infrared spectral data to obtain the overlapping peak baseline, making the subsequent calculations of the overlapping peak area and the characteristic peak area corresponding to the Si-OC bond of the silane coupling agent more accurate. Utilizing the different peak wavenumbers of different chemical bonds in the infrared spectral data of percolator samples, and the proportion of the characteristic peak area corresponding to the Si-OC bond of the silane coupling agent in the overlapping peak area, a grafting rate correction model is constructed. Then, using the parameters corresponding to all batches of percolator samples, the grafting rate correction model is solved, allowing the observed grafting rate of the percolator to be corrected using infrared spectral data, thus improving the accuracy of percolator grafting rate detection. Attached Figure Description

[0028] Figure 1 The flowchart illustrates the steps of the infrared spectroscopy-based method for detecting the grafting rate of nano-desaturated adsorption permeate provided in this application. Detailed Implementation

[0029] Example 1

[0030] This embodiment provides a method for detecting the grafting rate of nano-desorption and permeation agents based on infrared spectroscopy. For details, please refer to [link to relevant documentation]. Figure 1 The method includes the following steps:

[0031] Step 1: Prepare multiple percolator samples in batches and obtain the infrared spectral data and observe the grafting rate of each percolator sample; divide each batch of percolator samples into multiple sub-samples of equal mass, perform washing and drying on each sub-sample a different number of times, and obtain the infrared spectral data and observe the grafting rate of each sub-sample.

[0032] In this embodiment, a silicon-based percolator is prepared using nano-silica particles as a framework and a silane coupling agent-mediated covalent grafting method. The preparation process of the silicon-based percolator is as follows:

[0033] 1) Take 10g of hydrophilic nano-silica (particle size 10nm-50nm, specific surface area 50m²). 2 / g-200m 2The sample (g) was placed in a muffle furnace and heated to 300-500℃ at a rate of 5℃ / min. It was then calcined at this temperature for 2-4 hours and allowed to cool naturally to room temperature (resulting in a 20%-30% increase in silanol content). If the surface contained metallic impurities, 5% dilute hydrochloric acid was added to the calcined sample, and the mixture was stirred at room temperature for 2 hours. The sample was then centrifuged and washed until neutral to obtain activated nano-silica, which was then vacuum dried for later use.

[0034] 2) Take 2g of silane coupling agent KH-560, add 50mL of anhydrous ethanol, and stir well; add glacial acetic acid dropwise to adjust the pH of the system to 3-5; stir at room temperature for 30min-60min to obtain a transparent hydrolysate.

[0035] 3) Disperse 5g of activated nano-silica in 150mL of anhydrous ethanol and sonicate for 30min; slowly add the above transparent hydrolysate, heat to 50℃-60℃, and stir at a constant temperature for 4h-6h; centrifuge and wash 3 times, and vacuum dry to obtain epoxy-modified silica.

[0036] 4) Add 5g of PEG (polyethylene glycol) with a molecular weight of Y to the obtained epoxy-modified silica at a SiO2:PEG mass ratio of 1:1. The value of Y is in the range of 1000, 2000, 3000, 4000, and 3000 in this example. Then add 0.1g of p-toluenesulfonic acid (catalyst), heat to 75℃-80℃, and reflux for 8h-12h.

[0037] 5) Cleaning and drying: Centrifuge the obtained mixture at 5000 r / min for 10 min, wash it 3-5 times with a mixture of ethanol and acetone, and vacuum dry it at 50℃-60℃ for 24 h. The obtained covalent grafted product is named SiO2-PEG permeating agent. This permeating agent belongs to the silicon-based permeating agent category.

[0038] Grafting rate is a key indicator for quantifying the performance of nano-permeabilizers, reflecting the degree of coverage of PEG molecular chains on the surface of silica (SiO2) nanoparticles. There is a negative correlation between grafting rate and water molecule adsorption; the higher the grafting rate, the stronger the steric hindrance effect of the PEG molecular chains, and consequently, the lower the adsorption of water molecules by the silica nanoparticles on the reservoir rock surface.

[0039] In the process of measuring grafting rate using thermogravimetric analysis (TGA, N2 atmosphere), the heating rate was set to 10℃ / min, and the temperature test range was 30℃-800℃, with mass loss curves recorded. The main reason for setting this temperature test range is that pure nano-silica has extremely high thermal stability, with a char residue rate of ≤5% at 800℃, while PEG can completely decompose at 200℃-400℃. After the thermogravimetric analysis, the grafting rate was measured using the formula: The grafting rate of the prepared SiO2-PEG permeabilizer can then be calculated. The method of calculating the grafting rate using thermogravimetric analysis is a well-known technique, and the specific process will not be elaborated further.

[0040] However, in practice, due to incomplete hydrolysis or insufficient washing, residual silane coupling agent may be present in the prepared SiO2-PEG percolator. This causes the KH-560 epoxy group to undergo ring-opening polymerization / decomposition at 280℃~350℃, resulting in additional weight loss and ultimately leading to an overestimation of the grafting rate measured by thermogravimetric analysis.

[0041] In infrared spectroscopy, the peak positions of specific chemical bonds are fixed. However, during covalent grafting, a new Si-OC bond peak (1020 cm⁻¹) can be added. -1 When this characteristic peak appears, it indicates that the SiO2-PEG percolator grafting was successful. In infrared spectroscopy, the grafting rate can be corrected by the ratio of Si-OC bonds.

[0042] Based on the above analysis, using the above method for preparing SiO2-PEG permeating agent, M (M is the preset total number of batches, 20 in this embodiment) SiO2-PEG permeating agent samples were prepared in batches, resulting in SiO2-PEG permeating agent samples with a mass of U (U is the preset mass; to ensure that the mass of each sample after subsequent equal mass division is not less than 2g, its value is greater than or equal to 20g, 30g in this embodiment) per batch.

[0043] Infrared spectroscopy was performed on each batch of samples, with a specific scanning wavenumber range of 4000~400cm. -1 The resolution of the infrared spectrum should be higher than 1 cm⁻¹. -1 Infrared spectral data of each batch of samples were obtained. Simultaneously, thermogravimetric analysis (TGA) was performed on each batch of samples to obtain the grafting rate, which was recorded as the observed grafting rate for each batch.

[0044] In this embodiment, taking any batch of SiO2-PEG permeate sample as an example, it is divided into n (n is a preset number of parts, which is 10 in this embodiment) sub-samples of equal mass, and each sub-sample is numbered; then each sub-sample is cleaned and dried using different numbers of cleaning and drying cycles. For example, sub-sample 1 is cleaned and dried once, sub-sample 2 is cleaned and dried twice, sub-sample 3 is cleaned and dried three times, and so on, to obtain 10 sub-samples with different numbers of cleaning and drying cycles.

[0045] Similarly, infrared spectroscopy measurements were performed on each subsample to obtain the corresponding infrared spectral data. Simultaneously, thermogravimetric analysis (TGA) was performed on each subsample to obtain the grafting rate, which was then recorded as the observed grafting rate for each subsample.

[0046] In addition, in order to calibrate the SiO2-PEG percolator, pure nano-SiO2, pure PEG and silane coupling agent of the same mass as each subsample were selected for infrared spectroscopy measurement to obtain the infrared spectral data of each pure nano-SiO2, pure PEG and silane coupling agent.

[0047] It should be noted that the collected infrared spectral data is susceptible to interference from environmental factors to varying degrees. To achieve interference-resistant alignment of the infrared spectral data, a uniform spectral shift processing was performed on the original infrared spectral data of each batch of SiO2-PEG percolator samples and each subsample. Specifically, firstly, for the infrared spectral data corresponding to any sample, a 4000cm segment was truncated. -1 -3800cm -1 The infrared spectral data is divided into wavenumber ranges, and the average absorbance of these ranges is recorded as the background absorbance of the corresponding infrared spectral data. Then, the corresponding ordinate amplitude of the original infrared spectral data is uniformly subtracted from its background absorbance, outputting the infrared spectral data of the corresponding sample after spectral shifting. Min-maximum normalization is performed on all infrared spectral data to obtain the spectral shifted and normalized infrared spectral data for each sample, which is used for subsequent area integration and absorbance extraction calculations. The minimum and maximum values ​​for normalization are obtained based on the infrared spectral data of all batches of SiO2-PEG percolator samples and all sub-samples.

[0048] Thus, infrared spectral data and observed grafting rate of each batch of percolator samples, as well as infrared spectral data and observed grafting rate of each subsample, were obtained.

[0049] Step 2: Extract overlapping peaks from the infrared spectral data of each subsample, and obtain the baseline of the overlapping peaks by utilizing the correlation between the overlapping peak area of ​​all subsamples under different baselines and the observed grafting rate.

[0050] The SiO2-PEG permeating agent formed after covalent grafting exhibits a new characteristic peak of Si-OC, which can be used to determine whether the grafting was successful. Furthermore, the area ratio of the Si-OC characteristic peak indicates the proportion of successfully grafted chemical bonds, thus indirectly reflecting the grafting rate. However, in practice, the residual silane coupling agent will also contain the Si-OC characteristic peak, making simple identification based on the characteristic peak impossible.

[0051] Although both SiO2-PEG penetrants and silane coupling agents contain characteristic peaks of Si-OC, theoretically the peak positions of the same chemical bonds in infrared spectral data should be the same. However, in practice, due to the electronic effects of the connecting chemical bonds, there will be positional shifts between the characteristic peaks of Si-OC in SiO2-PEG penetrants and silane coupling agents.

[0052] Specifically, in silane coupling agents, Si-OC is a bond connecting silicon atoms to methoxy / ethoxy groups (such as Si-O-CH3), which is an intramolecular chemical bond. The electronegative group (-OCH3) increases the Si-O bond force constant, causing the absorption peak to shift to higher wavenumbers. In contrast, grafted Si-OC is a bond connecting silicon atoms to carbon chains (such as Si-O-C2H4-), which is an intermolecular covalent bond. The carbon chain has weak electronegativity, resulting in a small Si-O bond force constant, causing the absorption peak to shift to lower wavenumbers. Furthermore, the peak shape is broadened due to the influence of the SiO2 framework.

[0053] Furthermore, based on the peak positions of each pure component, the characteristic peaks of each component in the infrared spectral data of each subsample are identified.

[0054] Theoretically, the spectral characteristics of the characteristic peak of pure nano-silica are: 1080 cm⁻¹ -1 The stretching vibration of the nearby Si-O-Si bond, 3400 cm⁻¹ -1 The stretching vibrations of the nearby Si-OH bonds. The spectral characteristics of pure PEG are: 1100 cm⁻¹. -1 Nearby COC ether bond stretching vibration, 2880 cm -1 The near-CH2-CH2 stretching vibration shows an increasing peak intensity with increasing PEG molecular weight. In covalently grafted SiO2-PEG percolators, the Si-OC bond typically has a peak intensity around 1020 cm⁻¹. -1 Characteristic peaks appear nearby, while in pure silane coupling agents, the silicon atoms in the Si-OC bond are connected to the more electronegative methoxy / ethoxy groups, causing the absorption peak to shift to higher wavenumbers. Therefore, the characteristic peak of the Si-OC bond typically appears at 1150 cm⁻¹. -1 ~1250cm -1 Within the range.

[0055] To avoid peak deviation between theoretically labeled peaks and actual measurements, the 1080 cm⁻¹ peak in the infrared spectral data of pure nano-silica was analyzed. -1 Nearby peak values ​​are matched, and the wave number of the corresponding peak value is recorded as . ; 1150 cm⁻¹ in the infrared spectral data of pure silane coupling agents -1 ~1250cm -1 The peak values ​​within the range are matched to characterize the elution positions of Si-OC bonds in silane coupling agents, and the wavenumbers corresponding to the peak values ​​are denoted as follows: Meanwhile, the infrared spectral data of pure PEG showed a value of 1100 cm⁻¹. -1 Nearby matching peaks, the wavenumber corresponding to that peak is denoted as For the different chemical bond peak wavenumbers obtained above, if the prepared SiO2-PEG permeating agent contains the corresponding component, a corresponding characteristic peak will also be generated at the corresponding peak wavenumber position.

[0056] Furthermore, during the preparation of SiO2-PEG permeating agent using the silane coupling agent-mediated covalent grafting method, there may be residual silane coupling agent. Therefore, during the thermogravimetric analysis to determine the grafting rate, the residual silane coupling agent in the SiO2-PEG permeating agent will cause additional mass loss, which will lead to a large deviation in the determination of the grafting rate and interfere with the quantification of the grafting rate of SiO2-PEG permeating agent.

[0057] In the infrared spectral data of each sample, Si-O-Si bonds, Si-OC bonds (including Si-OC bonds in SiO2-PEG permeating agents and Si-OC bonds in silane coupling agents) and COC ether bonds will coexist. At the same time, since the peak wavenumbers of the three are relatively close, the characteristic peaks are difficult to distinguish and further analysis is needed based on the peak distribution of the infrared spectral data.

[0058] In infrared spectral data, the size of the characteristic peak area directly reflects the content of the corresponding component. Obtaining the characteristic peak area requires integrating the infrared spectral curve, which necessitates determining the baseline of the infrared spectrum to identify the integration boundary of the characteristic peak area. The baseline in infrared spectral data is susceptible to fluctuations from external factors and cannot be easily obtained using baseline correction algorithms. The overlapping peaks of Si-O-Si bonds, Si-OC bonds (including those in SiO2-PEG percolators and silane coupling agents), and COC ether bonds in the infrared spectral data of each subsample are denoted as the overlapping peaks of each subsample, specifically at 1000 cm⁻¹. -1 ~1250cm -1 Characteristic peaks within a wavenumber range. The baselines of all characteristic peaks (characteristic peaks formed by the superposition of multiple chemical bonds) within a single overlapping peak are consistent.

[0059] Therefore, the formula for calculating the overlapping peak area in the infrared spectral data of a single subsample is constructed as follows: In the formula, This represents the overlapping peak area of ​​the infrared spectral data of the i-th subsample. The baseline representing the overlapping peaks. This represents the infrared spectral curve corresponding to the overlapping peak of the i-th subsample. , denoted as the wavenumber corresponding to the cross-start point and the cross-end point of the overlapping peak baseline and the overlapping peak of the i-th subsample, respectively.

[0060] It should be noted that the baselines corresponding to the overlapping peaks in the infrared spectral data of all subsamples are the same.

[0061] Furthermore, there are differences in the number of cleaning cycles between the various subsamples. During the cleaning process, only the residual silane coupling agent can be removed, but the chemical bond components corresponding to the SiO2-PEG permeating agent cannot be removed. That is, as the cleaning proceeds, the area of ​​the overlapping peak will gradually decrease, and the portion of the reduced overlapping peak area corresponds to the silane coupling agent that has been cleaned out of the SiO2-PEG permeating agent.

[0062] The presence of silane coupling agents in each subsample introduces interference, leading to additional mass loss during thermogravimetric analysis and increasing the observed grafting rate. Therefore, as the number of washing cycles increases, the observed grafting rate for each subsample gradually decreases.

[0063] During the cleaning process, subsamples cleaned fewer times contained a relatively higher amount of silane coupling agent, making them easier to clean and resulting in the removal of more silane coupling agent components. Therefore, as the number of cleaning cycles increased, the removal difficulty gradually increased, causing the silane coupling agent content in the corresponding subsamples to decrease exponentially; that is, the overlapping peak area of ​​the subsamples gradually decreased exponentially. The change in the overlapping peak area was basically synchronized with the observed grafting rate. That is, when the observed grafting rate no longer changed with the number of cleaning cycles, it indicated that the residue had been largely removed, and the corresponding overlapping peak area would also no longer change.

[0064] However, if the baseline is not selected properly, there may be cases where the silane coupling agent is present but is filtered out by the baseline in advance. This causes the overlapping peak area to no longer change, but the observed grafting rate still decreases with the number of washes, resulting in a worse correlation between the overlapping peak area and the observed grafting rate.

[0065] Based on the relationship between the overlapping peak area of ​​subsamples and the baseline, and the correlation between the observed grafting rate and the overlapping peak area under different baselines, the baseline of the overlapping peak is obtained. The specific acquisition process is as follows:

[0066] 1) Traverse each baseline within the preset baseline range (set to 0.90-0.96 in this embodiment) with a preset step size (0.001 in this embodiment), and substitute each baseline into the overlapping peak area calculation formula to calculate the overlapping peak area of ​​each subsample under each baseline.

[0067] 2) Using the overlapping peak area and observed grafting rate of all subsamples of all batches of percolator samples under a single baseline as input, curve fitting is performed using the least squares method, where the observed grafting rate is used as the dependent variable and the overlapping peak area is used as the independent variable, to obtain the fitting function and fitting error corresponding to a single baseline.

[0068] 3) Obtain the fitting function and fitting error corresponding to all baselines. Record the baseline corresponding to the minimum fitting error as the baseline of the overlapping peak. The fitting function corresponding to the obtained baseline is the functional relationship between the observed grafting rate of the subsample and its overlapping peak area. It should be noted that the overlapping peak baselines are the same for percolator samples from different batches.

[0069] Step 3: Based on the variation characteristics between the number of washing and drying cycles and the observed grafting rate of each batch of sub-samples, obtain the true grafting rate of each batch of percolator samples; based on the proportion of the characteristic peak area corresponding to the Si-OC bond of the silane coupling agent in the overlapping peak area corresponding to the overlapping peak baseline of each percolator sample, construct a grafting rate correction model, and solve the grafting rate correction model using the true grafting rate, observed grafting rate, overlapping peak area, and infrared spectral absorbance at the peak wavenumber of the Si-OC bond of the silane coupling agent in the infrared spectral data of all batches of percolator samples.

[0070] Furthermore, as the number of drying and washing cycles for any batch of subsamples gradually increases, the fewer Si-OC bonds in the silane coupling agent, the less interference it causes to the infrared spectral determination of Si-OC bonds in the SiO2-PEG permeator. If the overlapping peak area and observed grafting rate still decrease after n washing cycles, it indicates that the number of washing cycles is insufficient. In this case, the number of washing and drying cycles for the subsamples needs to be further increased until the overlapping peak area and observed grafting rate no longer change with the increase of washing and drying cycles. The observed grafting rate at which the observed grafting rate no longer changes is recorded as the true grafting rate of the current batch of SiO2-PEG permeator sample.

[0071] Similarly, the true grafting rate of each batch of percolator samples can be obtained using the above method.

[0072] Furthermore, the overlapping peak areas of the percolator samples from each batch contain components contributed by the Si-OC bonds in the silane coupling agent. The Si-OC bonds in the silane coupling agent will overlap with the normal components in the SiO2-PEG percolator, making it impossible to directly determine the characteristic peak area contributed by the Si-OC bonds in the silane coupling agent.

[0073] If the overlapping peak areas corresponding to the infrared spectral data of each batch of percolator samples contain contributions from the Si-OC bonds in the silane coupling agent, then the peak wavenumbers of each batch of percolator samples will be... The corresponding peak value will be proportional to the characteristic peak area contributed by the Si-OC bond in the silane coupling agent.

[0074] Therefore, a grafting rate correction model is constructed: In the formula, This represents the true grafting rate of the j-th batch of percolator samples; This indicates that in the infrared spectral data of the j-th batch of percolator sample... The infrared absorbance at the wavenumber; The peak wavenumber of the Si-OC bond in the silane coupling agent; This represents the fitting coefficient (which is an unknown quantity that needs to be determined through fitting). The baseline representing the overlapping peaks; This represents the overlapping peak area of ​​the j-th batch of percolating agent samples; This represents the observed grafting rate of the j-th batch of percolator samples.

[0075] in, The area of ​​the characteristic peak corresponding to the Si-OC bond in the silane coupling agent in the infrared spectral data used to characterize the j-th batch of percolator samples; the proportion of the actual grafting in the observed grafting rate is quantified by calculating the proportion of the characteristic peak corresponding to the Si-OC bond in the SiO2-PEG percolator sample in the overlapping peak area.

[0076] The true grafting rate, overlapping peak area, and infrared spectral data of all batches of SiO2-PEG percolator samples were obtained. The infrared spectral absorbance at the corresponding wavenumber and the observed grafting rate are used as inputs, with the actual grafting rate as the dependent variable, and the overlapping peak area and the infrared spectral data as inputs. The infrared spectral absorbance at the wavenumber and the observed grafting rate are used as independent variables. After being substituted into the grafting rate correction model, the least squares method is used to perform linear regression fitting. Finally, the specific value of the fitting coefficient k is solved to obtain the solved grafting rate correction model.

[0077] Step 4: Using the solved grafting rate correction model, as well as the observed grafting rate and infrared spectral data of the penetrant sample to be tested, calculate the true grafting rate of the penetrant sample to be tested.

[0078] For the SiO2-PEG percolator sample to be tested, the corresponding infrared spectral data were obtained by infrared spectroscopy measurement, and the infrared spectral data were subjected to spectral shifting and normalization.

[0079] The overlapping peak area can be calculated using the formula for calculating the overlapping peak area in the infrared spectral data of the SiO2-PEG penetrant sample to be tested; the overlapping peak area in the obtained infrared spectral data can then be calculated. The infrared absorbance at the corresponding wavenumber was determined; and the observed grafting rate of the SiO2-PEG percolator sample to be tested was obtained through thermogravimetric analysis. The overlapping peak area and infrared spectral data of the SiO2-PEG percolator sample to be tested were then compared. The infrared absorbance at the wavenumber and the observed grafting rate are substituted into the grafting rate correction model obtained by solving the problem to obtain the true grafting rate of the SiO2-PEG permeabilizer sample to be tested.

[0080] The above method corrects the observed grafting rate by using the overlapping peak characteristics in infrared spectral data, reducing the interference of silane coupling agent residues on thermogravimetric analysis and improving the accuracy of grafting rate detection.

[0081] Example 2

[0082] In another embodiment of this application, a method for detecting the grafting rate of a nano-desorption permeabilizer based on infrared spectroscopy is provided, specifically including the following steps:

[0083] This embodiment uses graphene quantum dots as a framework and employs a silane coupling agent-mediated covalent grafting method to prepare a carbon-based percolator. One method for preparing the carbon-based percolator in this embodiment is as follows:

[0084] 1) An aqueous solution of GQDs (graphene quantum dots) prepared by hydrothermal method (concentration 10 mg / mL) was placed in a dialysis bag (molecular weight cutoff 3500 Da) and dialyzed in deionized water for 48 h, with the water changed every 12 h to remove small molecule impurities. The dialyzed solution was centrifuged at 8000 r / min for 10 min, and a small amount of agglomerated precipitate at the bottom was discarded. The supernatant was collected and freeze-dried under vacuum for 24 h to obtain powdered GQDs. The dried GQDs were dispersed in 30% H2O2 solution, sonicated for 2 h, and centrifuged and washed until neutral.

[0085] 2) Take 1.0g of silane coupling agent KH-560, add 50mL of anhydrous ethanol, and stir well; add glacial acetic acid dropwise to adjust the pH of the system to 3-5; stir at room temperature for 30min to obtain a transparent hydrolysate.

[0086] 3) Disperse 0.5g of purified GQDs in 100mL of anhydrous ethanol and sonicate for 30min; slowly add the above hydrolysate, heat to 60℃, and stir at a constant temperature for 4h to anchor KH-560 on the surface of GQDs; centrifuge and wash 3 times (8000r / min×10min), and vacuum dry (60℃, 12h) to obtain epoxy-modified GQDs.

[0087] 4) Redisperse the epoxy-modified GQDs in 50 mL of anhydrous ethanol, add 0.5 g of PEG with molecular weight Y, add 0.05 g of p-toluenesulfonic acid (catalyst to promote epoxy ring opening), heat to 75 °C, and reflux for 10 h.

[0088] 5) Slowly pour the reaction solution into 200 mL of anhydrous diethyl ether and let it stand for 10 min. GQDs-PEG will precipitate. Centrifuge at 8000 r / min for 10 min and collect the precipitate. Wash three times with an ethanol-diethyl ether mixture (volume ratio 1:1). Place it in a dialysis bag (MWCO 3500 Da) and dialyze with deionized water for 24 h to remove unreacted mPEG-NH2 and catalyst. Freeze dry under vacuum (-50℃, 24 h). The resulting silane coupling agent-mediated covalent grafting product is named GQDs-PEG percolator. This percolator belongs to the carbon-based percolator category.

[0089] When performing infrared spectroscopy on GQDs-PEG permeating agents, a value of 3400 cm⁻¹ will be observed. -1 The nearby -OH stretching vibration, 1600 cm -1 The nearby C=C aromatic ring vibrates at 1100 cm. -1 The stretching vibration of the nearby COC ether bond, 2880 cm⁻¹ -1 The stretching vibration of the nearby CH (-CH2-CH2-) increases, and the peak intensity increases with the increase of PEG molecular weight. The 1080 cm⁻¹ peak of the Si-O bond... -1 Stretching vibrations, and Si-OC bonds in silane coupling agents at 1150 cm⁻¹ -1 ~1250cm -1 Expansion and contraction vibration within a certain range.

[0090] At this point, the overlapping peaks in the infrared spectral data of the GQDs-PEG percolator sample refer to the peaks formed by the superposition of characteristic peaks of COC bonds, Si-O bonds, and Si-OC bonds in the silane coupling agent in the infrared spectral data. The wavenumber range of these overlapping peaks is 1000 cm⁻¹. -1 ~1250cm -1 .

[0091] Similarly, to avoid interference from residual Si-OC bonds in the silane coupling agent on the grafting rate determination of GQDs-PEG permeate, the methods described in steps one and two of Example 1 were used to prepare multiple batches of GQDs-PEG permeate samples using the above-mentioned preparation method. The baseline of overlapping peaks in the infrared spectral data of the GQDs-PEG permeate samples was obtained. The observed grafting rate of the GQDs-PEG permeate samples was corrected by infrared spectroscopy using step three of Example 1 to obtain a grafting rate correction model. Then, the true grafting rate of the GQDs-PEG permeate sample to be tested was calculated using step four of Example 1.

Claims

1. A method for detecting the grafting rate of nano-adsorption and permeation agents based on infrared spectroscopy, characterized in that, The method includes the following steps: For any type of percolator, such as silicon-based or carbon-based percolators, multiple percolator samples were prepared in batches, and the infrared spectral data and grafting rate of each percolator sample were obtained. Each batch of percolator samples was divided into multiple sub-samples of equal mass, and each sub-sample was washed and dried a different number of times. The infrared spectral data and grafting rate of each sub-sample were obtained. The overlapping peaks in the infrared spectral data of each subsample are extracted, and the baseline of the overlapping peaks is obtained by utilizing the correlation between the overlapping peak area of ​​all subsamples under different baselines and the observed grafting rate. Based on the variation characteristics between the number of washing and drying cycles and the observed grafting rate of each batch of subsamples, the true grafting rate of each batch of percolator samples is obtained. Based on the proportion of the characteristic peak area corresponding to the Si-OC bond of the silane coupling agent in the overlapping peak area corresponding to the overlapping peak baseline of each percolator sample, a grafting rate correction model is constructed. The grafting rate correction model is solved by using the true grafting rate, observed grafting rate, overlapping peak area, and infrared absorbance at the peak wavenumber of the Si-OC bond of the silane coupling agent in the infrared spectral data of all batches of percolator samples. Using the solved grafting rate correction model, along with the observed grafting rate and infrared spectral data of the absorbent sample to be tested, the true grafting rate of the absorbent sample to be tested is calculated.

2. The method for detecting the grafting rate of nano-adsorption desorption agents based on infrared spectroscopy as described in claim 1, characterized in that, Silicon-based absorbents are absorbents made using nano-silica as a framework, while carbon-based absorbents are absorbents made using graphene quantum dots as a framework.

3. The method for detecting the grafting rate of nano-adsorption desorption agents based on infrared spectroscopy as described in claim 1, characterized in that, The observed grafting rate refers to the grafting rate measured using thermogravimetric analysis.

4. The method for detecting the grafting rate of nano-desaturating adsorption agents based on infrared spectroscopy as described in claim 1, characterized in that, The method for extracting overlapping peaks in the infrared spectral data of each subsample is as follows: If the subsample is a silicon-based penetrant, its overlapping peak refers to the peak formed by the superposition of the characteristic peaks of Si-O-Si bonds, Si-OC bonds and COC bonds in its infrared spectral data; If the subsample is a carbon-based percolator, its overlapping peak refers to the peak formed by the superposition of the characteristic peaks of COC bond, Si-O bond and Si-OC bond in its infrared spectral data.

5. The method for detecting the grafting rate of nano-adsorption and permeation agents based on infrared spectroscopy as described in claim 1, characterized in that, The method for calculating the overlapping peak area in the infrared spectral data of each subsample is as follows: In the formula, This represents the overlapping peak area of ​​the infrared spectral data of the i-th subsample. The baseline representing the overlapping peaks. This represents the infrared spectral curve corresponding to the overlapping peak of the i-th subsample. , denoted as the wavenumber corresponding to the cross-start point and the cross-end point between the baseline of the overlapping peak and the overlapping peak of the i-th subsample, respectively.

6. The method for detecting the grafting rate of nano-adsorption desorption agents based on infrared spectroscopy as described in claim 5, characterized in that, The process of obtaining the baseline of the overlapping peak is as follows: Within the preset baseline range, each baseline is traversed with a preset step size, and each is substituted into the overlapping peak area calculation formula to calculate the overlapping peak area of ​​each subsample under each baseline. Using the overlapping peak area and observed grafting rate of all sub-samples of all batches of percolating agent samples under a single baseline as input, curve fitting is performed using the least squares method, where the observed grafting rate is used as the dependent variable and the overlapping peak area is used as the independent variable, to obtain the fitting function and fitting error corresponding to a single baseline. Obtain the fitting function and fitting error corresponding to all baselines, and denote the baseline corresponding to the minimum fitting error as the baseline of the overlapping peak.

7. The method for detecting the grafting rate of nano-adsorption desorption agents based on infrared spectroscopy as described in claim 1, characterized in that, The true grafting rate of each batch of percolator samples refers to the observed grafting rate when the overlapping peak area and the observed grafting rate no longer change with the increase of washing and drying times for each batch of subsamples.

8. The method for detecting the grafting rate of nano-desaturating adsorption agents based on infrared spectroscopy as described in claim 1, characterized in that, The grafting rate correction model is constructed as follows: In the formula, This represents the true grafting rate of the j-th batch of percolator samples; This indicates that in the infrared spectral data of the j-th batch of percolator sample... The infrared absorbance at the wavenumber; The peak wavenumber of the Si-OC bond in the silane coupling agent; Represents the fitting coefficient; The baseline representing the overlapping peaks; This represents the overlapping peak area of ​​the j-th batch of percolating agent samples; This represents the observed grafting rate of the j-th batch of percolator samples.

9. The method for detecting the grafting rate of nano-desaturating adsorption agents based on infrared spectroscopy as described in claim 8, characterized in that, The solution process for the grafting rate correction model is as follows: The true grafting rate, overlapping peak area, and infrared spectral data corresponding to all batches of percolator samples were analyzed. The infrared spectral absorbance at the corresponding wavenumber and the observed grafting rate are used as inputs, with the actual grafting rate as the dependent variable, and the overlapping peak area and the infrared spectral data as inputs. The infrared spectral absorbance at the wavenumber and the observed grafting rate are used as independent variables. After being substituted into the grafting rate correction model, the least squares method is used to perform linear regression fitting to solve for the specific value of the fitting coefficient k, thus obtaining the solved grafting rate correction model.

10. The method for detecting the grafting rate of nano-desaturating adsorption agents based on infrared spectroscopy as described in claim 8, characterized in that, The method for calculating the true grafting rate of the penetrant sample to be tested is as follows: The overlapping peak area and infrared spectral data corresponding to the penetrant sample to be tested are compared and analyzed. The infrared absorbance at the wavenumber and the observed grafting rate are substituted into the solved grafting rate correction model to obtain the true grafting rate of the penetrant sample to be tested.

Images