Method for detecting content of bio-based carbon in bio-based coating product

Abstract

The invention relates to the technical field of bio-based carbon detection, in particular to a method for detecting the content of bio-based carbon in a bio-based coating product, which comprises the following steps: step 1, removing a solvent in a bio-based coating sample and eliminating the influence of volatile organic compounds (VOC) by adopting a freeze-drying technology; step 2, measuring the organic carbon content of the bio-based coating sample, the reference sample oxalic acid 4990C and the blank sample pulverized coal, quantifying the mass of the bio-based coating sample and the pulverized coal according to the organic carbon measurement result by taking the organic carbon content of the oxalic acid 4990C as a reference, and performing a programmed temperature control oxidative combustion test; and 3, after the oxidative combustion test is finished, collecting the sample at the absorption end, and carrying out a measurement test by adopting a liquid flash counter to obtain the bio-based carbon content in the sample. According to the method, the pretreatment process is combined with freeze-drying pretreatment and programmed oxidation combustion, and the detection process is optimized, so that the detection accuracy and repeatability are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bio-based carbon detection, and particularly relates to a method for detecting the content of bio-based carbon in a bio-based coating product. BACKGROUND

[0002] Bio-based coating refers to the main components in the coating, such as resin film-forming substances, curing agents or related auxiliary agents, which are produced from renewable resources such as castor oil, corn starch, sugar, etc., which are different from traditional coating raw materials extracted from petroleum chemical industry, thereby reducing carbon dioxide emissions and dependence on petroleum.

[0003] In the prior art, there is no clear and effective method for qualitative detection of bio-based carbon in bio-based coating products and determination of the content thereof. At present, the detection of bio-based carbon mainly aims at 14 qualitative detection of C isotopes, and the detection methods mainly include accelerator mass spectrometry (AMS method), BI method and ultra-low background liquid scintillation counting method (LSC method). The AMS method has the advantages of high precision, but its operation is extremely complex, and the cost of a single machine is tens of millions of yuan, which limits its large-scale use. The BI method not only has very high requirements for the test environment, but also has relatively complex operation, which also limits its actual application. In summary, the LSC method is simple in operation, relatively low in cost, low in requirements for the test environment, and suitable for large-scale practical application. However, the precision of the LSC method is greatly affected by the detection process and operation, so it is necessary to establish a systematic detection method for the content of bio-based carbon in coating products. SUMMARY

[0004] In view of the above deficiencies in the prior art, the present application aims to provide a method for detecting the content of bio-based carbon in a bio-based coating product, which more accurately measures the content of bio-based carbon in the bio-based coating product by optimizing the pretreatment process and combining an ultra-low background liquid scintillation counter.

[0005] In order to achieve the above-mentioned application purposes, the technical scheme adopted by the present application is as follows: A method for detecting the content of bio-based carbon in a bio-based coating product is provided, which comprises the following steps: Step 1: using freeze-drying technology to remove the solvent in the bio-based coating sample without destroying the structure of the sample and eliminating the influence of volatile organic compounds (VOCs); Step 2: measuring the organic carbon content of the bio-based coating sample, the reference sample oxalic acid 4990C and the blank sample coal powder by the solid-state measurement module of the total organic carbon / total carbon analyzer, and quantifying the mass of the bio-based coating sample and the coal powder according to the organic carbon measurement results, taking the organic carbon content of the oxalic acid 4990C as the reference, and performing an oxidation combustion test; Step 3, after the end of the oxidation combustion test, the sample at the absorption end is collected and measured by liquid scintillation counting to obtain the bio-based carbon content in the sample.

[0006] Further, in step 1, the freeze-drying temperature is set to -60 DEG C, and the vacuum degree is 0 MPa.

[0007] Further, in step 2, the oxidation combustion uses a programmed temperature three-stage combustion, mainly including a programmed temperature zone, an intermediate zone and a catalytic zone, so that the carbon in the sample is fully converted into CO2, and the temperature range is room temperature-900 DEG C.

[0008] Further, the temperature of the catalytic zone during the combustion process is set to 800 DEG C, the programmed temperature zone is set to 100 DEG C for 20 minutes to make the moisture fully volatilize, 100-200 DEG C for carbonization, 200 DEG C for 40 minutes, 200-400 DEG C for carbonization and oxidation, 400 DEG C for 40 minutes, 400-600 DEG C for oxidation combustion, 600 DEG C for 40 minutes, so that the sample is fully converted into CO2, 900 DEG C for 10 minutes, and the catalytic zone is kept at 800 DEG C during the oxidation combustion process.

[0009] Further, a cold trap, a desiccant tube and a Carbo-sorb absorption liquid tube are connected to the tail pipe of the oxidation combustion furnace to absorb the moisture, and the absorption liquid tube is placed in an ice bath, and the gas outlet of the absorption liquid tube is connected to the ice bath by a rubber tube to reduce the temperature and prevent the Carbo-sorb absorption liquid from volatilizing.

[0010] Further, in the oxidation combustion test, the flow ratio of oxygen and nitrogen is 1:1, and the pressure is 0.15 MPa.

[0011] Further, in step 3, the sample collected after the oxidation combustion is taken into a low potassium glass bottle, Permafluor E+ scintillation liquid is added, and the low potassium glass bottle is shaken thoroughly, then the surface of the low potassium glass bottle is wiped with an ethanol solution to remove static electricity.

[0012] Further, the detection time is set to 300 minutes, and the energy window range is 4-156 keV.

[0013] The beneficial effects of the present application are: The present application significantly improves the detection accuracy and repeatability of the bio-based carbon content in the bio-based coating product by the pretreatment process combined with freeze-drying pretreatment and programmed oxidation combustion, and the optimization of the detection process. DETAILED DESCRIPTION

[0014] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0015] Experimental Example 1 Testing of water-based acrylic resin-based bio-based coatings: (1) Sample preparation Weigh 20g of water-based acrylic resin-based bio-based coating sample and place it in the lower freeze dryer of a freeze dryer. Freeze for 24 hours, then immediately place it in the upper freeze dryer and evacuate for 72 hours. The freeze-drying temperature was set at -60℃ and the vacuum degree was 0MPa.

[0016] After vacuum drying, the freeze-dried sample is placed in a glass desiccator and brought to room temperature.

[0017] The freeze-dried sample was ground into powder and sieved through a 12-mesh sieve. The sieved sample was then collected and stored in a low-potassium glass bottle.

[0018] This experimental example uses freeze-drying technology to remove solvents from samples and eliminate the effects of volatile organic compounds (VOCs) without damaging the sample structure.

[0019] (2) Determination of organic carbon content Three parallel samples, each 60 mg, were weighed into a ceramic combustion boat and hydrochloric acid solution was added. After the hydrochloric acid evaporated, the organic carbon content of the samples was measured using the solid-state measurement module of the total organic carbon / total carbon analyzer.

[0020] The reference sample oxalic acid 4990C and the blank sample coal powder were set up. The test method for the organic carbon content of the reference sample oxalic acid 4990C and the blank sample coal powder was the same as above.

[0021] (3) Oxidative combustion Based on the organic carbon measurement results, using the organic carbon content of oxalic acid 4990C as a benchmark, the mass of pulverized coal powder samples and blank samples was quantified. The quantification process can refer to the definition of bio-based carbon content in GB / T 29649-2013 (the percentage of the ratio of the radioactivity of organic carbon per gram of sample to the radioactivity of organic carbon per gram of modern carbon reference material). For example, if the organic carbon content of standard oxalic acid is determined to be 266 g / kg by an organic carbon analyzer, and 2 g of oxalic acid standard sample is taken, the organic carbon content of pulverized coal powder is measured to be 684 g / kg. To ensure that the organic carbon content of pulverized coal powder is consistent with that of standard oxalic acid, the sample amount of blank pulverized coal powder is 0.778 g. The sample amount can refer to that of blank pulverized coal powder. The quantified oxalic acid standard sample, bio-based coating sample, and blank pulverized coal powder were subjected to an oxidative combustion test, using a segmented combustion method.

[0022] Specifically, the oxidation combustion employs a programmed temperature-controlled three-stage combustion process, mainly comprising a programmed temperature control zone, an intermediate zone, and a catalytic zone, ensuring the complete conversion of carbon in the sample into CO2. The temperature range is room temperature to 900℃. The programmed temperature control zone is the oxidation combustion zone, the intermediate zone is the buffer zone, and the catalytic zone is the high-temperature reduction zone. During combustion, the catalytic zone temperature is set to 800℃. The oxidation process in the programmed temperature control zone begins with 100℃ for 20 minutes to allow for sufficient moisture evaporation, followed by carbonization at 100-200℃, maintained at 200℃ for 40 minutes, then carbonization and oxidation at 200℃ for 40 minutes, and finally, oxidation combustion at 400℃ for 40 minutes. To ensure complete conversion of the sample into CO2, the temperature is maintained at 900℃ for 10 minutes.

[0023] The combustion temperature and time settings in the above combustion process are for the programmed temperature control zone. No temperature is set in the intermediate buffer zone, and the temperature in the catalytic zone is continuously set to 800 degrees Celsius to achieve the reduction effect.

[0024] Open the main valves of the nitrogen and oxygen tanks, and adjust the gas flow rate in each quartz tube using the suspension flow meter on the instrument. Set the flow rate ratio of oxygen to nitrogen to 1:1 and the pressure to 0.15 MPa during the oxidation combustion test.

[0025] A cold trap, a desiccant tube, and a Carbo-sorb absorbent tube are connected to the tailpipe of the oxidation combustion furnace to absorb moisture. The absorbent tube is placed in an ice bath, and the outlet of the absorbent tube is connected to a rubber tube and placed in the ice bath to reduce the temperature and prevent the Carbo-sorb absorbent from evaporating.

[0026] The oxidation combustion process is as follows: Turn on the catalytic zone switch and set the catalytic zone temperature to 800℃.

[0027] When the temperature in the catalytic zone reaches 300 degrees Celsius, the temperature is controlled by adjusting the program settings.

[0028] After the program settings are complete, change the Status to Run state to start the instrument combustion program.

[0029] After combustion is complete, when the instrument temperature drops below 50°C, close the oxygen and nitrogen tank valves and turn off the power switch. Collect the sample from the absorption end for liquid scintillation counter measurement.

[0030] (4) Liquid scintillation counter measurement test Take 8 mL of the sample collected after oxidation and combustion into a low-potassium glass bottle, add 12 mL of Permafluor E+ scintillation solution, shake well, and then wipe the surface of the low-potassium glass bottle with ethanol solution to remove the effect of static electricity.

[0031] Place the prepared sample into the liquid scintillation counter instrument chamber, move the label to the far left, and close the sample chamber lid.

[0032] Connect the equipment to the power supply and open the QuantaSmart operating software. Set the sample counting program according to the specific sample requirements. In this experimental example, the counting time is set to 300 minutes, and the energy window range is 4-156 keV to reduce the background effect.

[0033] After counting is complete, open and view the data in the corresponding result saving path. The bio-based carbon content of the sample is calculated to be 27.2%.

[0034] Experimental Example 2 Testing of bio-based waterborne wood coatings: (1) Sample preparation Weigh 20g of water-based acrylic resin-based bio-based coating sample and place it in the lower freeze dryer of a freeze dryer. Freeze for 24 hours, then immediately place it in the upper freeze dryer and evacuate for 72 hours. The freeze-drying temperature was set at -60℃ and the vacuum degree was 0MPa.

[0035] After vacuuming, the freeze-dried sample is placed in liquid nitrogen and frozen for 20 minutes.

[0036] The sample, after being freeze-dried in liquid nitrogen, was ground into powder in a grinder with a sieve particle size of 1 mm. The ground sample was then collected directly into a combustion boat and sealed in a self-sealing bag for storage.

[0037] This experimental example uses freeze-drying technology to remove solvents from samples and eliminate the effects of volatile organic compounds (VOCs) without damaging the sample structure.

[0038] (2) Determination of organic carbon content Three parallel samples, each 60 mg, were weighed into a ceramic combustion boat and hydrochloric acid solution was added. After the hydrochloric acid evaporated, the organic carbon content of the samples was measured using the solid-state measurement module of the total organic carbon / total carbon analyzer.

[0039] The reference sample oxalic acid 4990C and the blank sample coal powder were set up. The test method for the organic carbon content of the reference sample oxalic acid 4990C and the blank sample coal powder was the same as above.

[0040] (3) Oxidative combustion Based on the organic carbon measurement results, the mass of pulverized coal powder samples and blank samples was quantified using the organic carbon content of oxalic acid 4990C as a benchmark. Oxidative combustion tests were then conducted on the quantified oxalic acid standard samples, bio-based coating samples, and blank pulverized coal powder samples, employing a segmented combustion method.

[0041] Specifically, the oxidation combustion employs a programmed temperature-controlled three-stage combustion process, mainly comprising a programmed temperature control zone, an intermediate zone, and a catalytic zone, ensuring the complete conversion of carbon in the sample into CO2. The temperature range is room temperature to 900℃. The programmed temperature control zone is the oxidation combustion zone, the intermediate zone is a buffer zone, and the catalytic zone is a high-temperature reduction zone. During combustion, the catalytic zone temperature is set to 800℃. The oxidation process in the programmed temperature control zone begins with 100℃ for 20 minutes to allow for sufficient moisture evaporation, followed by carbonization at 100-200℃, maintained at 200℃ for 40 minutes, then carbonization and oxidation at 200℃ for 40 minutes, and finally, oxidation combustion at 400℃ for 40 minutes, followed by 600℃ for 40 minutes. To ensure complete conversion of the sample into CO2, the temperature is maintained at 900℃ for 10 minutes.

[0042] Open the main valves of the nitrogen and oxygen tanks, and adjust the gas flow rate in each quartz tube using the suspension flow meter on the instrument. Set the flow rate ratio of oxygen to nitrogen to 1:1 and the pressure to 0.15 MPa during the oxidation combustion test.

[0043] A desiccant tube and a Carbo-sorb absorbent tube are connected to the tailpipe of the oxidation combustion furnace to absorb moisture. The absorbent tube is placed in an ice bath, and the outlet of the absorbent tube is connected to a rubber tube and placed in the ice bath to reduce the temperature and prevent the Carbo-sorb absorbent from evaporating.

[0044] Turn on the catalytic zone switch and set the catalytic zone temperature to 800℃.

[0045] When the temperature in the catalytic zone reaches 300 degrees Celsius, the temperature is controlled by adjusting the program settings.

[0046] After the program settings are complete, change the Status to Run state to start the instrument combustion program.

[0047] After combustion is complete, when the instrument temperature drops below 50°C, close the oxygen and nitrogen tank valves and turn off the power switch. Collect the sample from the absorption end for liquid scintillation counter measurement.

[0048] (4) Liquid scintillation counter measurement test Take 8 mL of the sample collected after oxidation and combustion into a low-potassium glass bottle, add 12 mL of Permafluor E+ scintillation solution, shake well, and then wipe the surface of the low-potassium glass bottle with ethanol solution to remove the effect of static electricity.

[0049] Place the prepared sample into the liquid scintillation counter instrument chamber, move the label to the far left, and close the sample chamber lid.

[0050] Connect the equipment to the power supply and open the QuantaSmart operating software. Set the sample counting program according to the specific sample requirements. In this experimental example, the counting time is set to 300 minutes, and the energy window range is 4-156 keV to reduce the background effect.

[0051] After the counting is completed, open and view the data in the corresponding result saving path. The bio-based carbon content of the sample is calculated to be 35.2%.

[0052] The oxalic acid standard sample 4990C (theoretical biobased carbon content of 100%) was tested using the optimized test method A and the conventional unoptimized test method B. The deviation of the mean measured value from the theoretical value (Bias, measuring accuracy), and the relative standard deviation (RSD, measuring repeatability) of 6 parallel measurements are shown in Table 1 below: Table 1: Comparison of measurement results for oxalic acid standard sample (4990C) Note: Method B involves drying the sample in an oven, grinding it into powder, and then directly performing the oxidation combustion process. The oxidation combustion process is not temperature-controlled; the temperature is directly raised from room temperature to 900℃ after the sample is placed in the oxidation combustion furnace, and then maintained at 900℃ for 30 minutes. The counting time during the counting process is set to 120 minutes, and the energy window range is 0-156 keV. Other procedures are the same as in Method A.

[0053] As shown in the table above, the measured values ​​of the method of this invention are in high agreement with the theoretical values, and the deviation is much smaller than that of conventional methods, proving its extremely high accuracy. At the same time, the RSD is much lower than that of conventional methods, proving its stable repeatability.

[0054] This invention significantly improves the accuracy and repeatability of detecting bio-based carbon content in bio-based coating products by combining freeze-drying pretreatment with programmed oxidation combustion and optimizing the detection process. Specifically, freeze-drying avoids carbon loss and fractionation during pretreatment, while programmed oxidation combustion ensures quantitative and complete carbon recovery, guaranteeing measurement accuracy from the source. The optimized absorption scintillation system and ultra-low background liquid scintillation counting program maximize the signal-to-noise ratio, reduce measurement uncertainty, and ultimately improve detection accuracy and repeatability.

[0055] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0056] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for detecting the biobased carbon content in a biobased coating product, characterized by, The method comprises the following steps: Step 1: removing the solvent in the bio-based coating sample by freeze-drying technology and eliminating the influence of volatile organic compounds (VOCs); Step 2: measuring the organic carbon content of the bio-based coating sample, the reference sample oxalic acid 4990C and the blank sample coal powder, quantifying the mass of the bio-based coating sample and the coal powder according to the organic carbon measurement result, and performing a programmed temperature oxidation combustion test based on the organic carbon content of the oxalic acid 4990C; Step 3: after the oxidation combustion test is completed, the sample at the absorption end is collected and measured by liquid scintillation counting to obtain the bio-based carbon content in the bio-based coating sample.

2. The method for detecting the biobased carbon content in a biobased coating product according to claim 1, characterized in that, In step 1, the freeze-drying temperature is set to -60°C, and the vacuum degree is 0 MPa.

3. The method for detecting the biobased carbon content in a biobased coating product according to claim 1, characterized in that, In step 2, the oxidation combustion adopts a programmed temperature three-stage combustion, including a programmed temperature zone, an intermediate zone and a catalytic zone, so that the carbon in the sample is fully converted into CO2, and the temperature range is room temperature-900°C.

4. The method for detecting the biobased carbon content in a biobased coating product according to claim 3, characterized in that, During the combustion process, the temperature of the catalytic zone is set to 800°C, the programmed temperature zone is set to 100°C for 20 minutes to make the water fully volatilize, 200°C for 40 minutes for carbonization, 200-400°C for carbonization and oxidation, 400°C for 40 minutes, 400-600°C for oxidation combustion, 600°C for 40 minutes, 900°C for 10 minutes to make the sample fully converted into CO2, and the catalytic zone is kept at 800°C during the oxidation combustion process.

5. The method for detecting the bio-based carbon content in a bio-based coating product according to claim 3, characterized in that, At the tail pipe of the oxidation combustion furnace, a cold trap, a desiccant tube and a Carbo-sorb absorption liquid tube are connected to absorb water, and the absorption liquid tube is placed in an ice bath to reduce the temperature and prevent the Carbo-sorb absorption liquid from volatilizing.

6. The method for detecting the biobased carbon content in a biobased coating product according to claim 3, characterized in that, In the oxidation combustion test, the flow ratio of oxygen and nitrogen is 1:1, and the pressure is 0.15 MPa.

7. The method for detecting the biobased carbon content in a biobased coating product according to claim 1, characterized in that, In step 3, the collected sample after oxidation combustion is placed in a low potassium glass bottle, Permafluor E+ scintillation liquid is added, and the low potassium glass bottle is shaken thoroughly, then ethanol solution is used to wipe the surface of the low potassium glass bottle to remove static electricity.

8. The method for detecting the biobased carbon content in a biobased coating product according to claim 7, characterized in that, The detection time is set to 300 minutes, and the energy window range is 4-156 keV.

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