A device and method for high-precision determination of solubility of hydrophobic organic matter in subcritical water

Abstract

The invention discloses a device and method for measuring the solubility of hydrophobic organic matter in subcritical water with high precision. The device of the invention comprises a quartz capillary balance kettle, a temperature controller, a circulating water system, a hot and cold stage, a camera, a microscope and a computer. The quartz capillary balance kettle is loaded with a quartz capillary with an outer diameter smaller than the inner diameter of the capillary balance kettle; the hydrophobic organic matter is absorbed in the quartz capillary and is open at both ends, and solvent water is injected into the quartz capillary balance kettle. The microscope is used to observe the images of the water in the quartz capillary balance kettle and the hydrophobic organic matter in the quartz capillary, and the camera is used to collect the images of the water and hydrophobic organic matter observed by the microscope, and transmit the image data to the computer. The method of the invention can accurately measure the solubility of different hydrophobic organic matter in subcritical water, and the device of the invention is simple, has high measurement accuracy, and is safe and efficient.

Description

Technical Field

[0001] The invention belongs to the field of chemistry, chemical engineering and environmental technology, and particularly relates to a device and method for high-precision determination of the solubility of hydrophobic organic matter in subcritical water. Background Art

[0002] Subcritical water technology has the advantages of being non-toxic, cheap and easily accessible, and has been gradually applied to the degradation and resource utilization of waste, the extraction of compounds such as polycyclic aromatic hydrocarbons and polychlorinated biphenyls from soil, and the preparation of microparticles of hydrophobic drugs and hydrophobic materials. Despite the huge advantages of subcritical water treatment technology, many potential applications remain untapped due to the lack of basic data. Solubility studies of hydrophobic organics in subcritical water are essential for separation and extraction process design because they quantify the ability of subcritical water to act as a solvent, thereby determining the feasibility and economic benefits of a particular process.

[0003] Due to the complexity and difficulty of phase equilibrium determination under high temperature and high pressure conditions, there are few solubility data of hydrophobic organics in the range of 100℃~374℃. At present, there are many methods and technologies that can be used for experimental research on high temperature and high pressure phase equilibrium, which can be divided into two categories: analytical method and synthetic method. The analytical method involves the analytical determination of the composition of coexisting phases. At the beginning of the experiment, when the equilibrium kettle is filled with various components, the mixture is separated into two or more phases under certain temperature and pressure conditions. Samples are taken from each phase and analyzed at the ambient pressure outside the equilibrium chamber or the phase composition in the equilibrium chamber is analyzed by physical and chemical methods. The synthetic method is to add a mixture of precisely known components to the equilibrium kettle, then observe the phase behavior in the equilibrium kettle, and measure the properties (such as pressure and temperature) under equilibrium state, without sampling. The synthetic method can be divided into visual synthesis method and non-visual synthesis method. Among the solubility determination methods of high temperature and high pressure systems, the visual synthesis method is the most commonly used method type. Researchers have established a variety of visual synthesis research devices, mainly using sapphire, quartz or glass equilibrium kettles or observation windows, and the analysis methods of phase equilibrium data are also different. For example, Fonseca et al. (Jose MS Fonseca, R Ohrn, S Peper. Journal of Supercritical Fluids, 2014, 86: 49-56) used visual synthesis to establish a stainless steel equilibrium kettle experimental device with a sapphire window to measure the solubility data of methane and carbon dioxide in water at a temperature of 243-353K and a pressure of 20MPa. The sapphire window is added with a scale, and after calibration, the volume occupied by each phase can be determined. The gas cylinder is separated from the reactor and weighed to determine the amount of gas added to the equilibrium kettle. Based on the volume and density of the gas phase at equilibrium, the solubility of the gas in the liquid phase can be calculated. This method has problems such as large equilibrium kettle volume and long equilibrium time. Summary of the invention

[0004] In view of the problems of complex and inefficient existing measurement technology devices, this application, based on the previous patent application CN202110247139.6, proposed a device and method for high-precision measurement of the solubility of hydrophobic organic matter in subcritical water through improved invention, which increases the measurement temperature range from 0-100°C to 100-374°C, and can withstand a maximum high pressure of 120MPa. Compared with the existing technology for measuring the solubility of hydrophobic inorganic substances in high-temperature and high-pressure subcritical water systems, the device of the present invention is simple, has high measurement accuracy, and is safe and efficient.

[0005] The device for high-precision determination of the solubility of hydrophobic organic matter in subcritical water comprises a quartz capillary balance kettle, a temperature controller, a circulating water system, a hot and cold stage, a camera, a microscope and a computer; wherein the quartz capillary balance kettle is loaded with a quartz capillary whose outer diameter is smaller than its inner diameter; the hydrophobic organic matter is absorbed in the quartz capillary and both ends are open, the solvent water is injected into the quartz capillary balance kettle and both ends are sealed, the temperature controller, the circulating water system and the hot and cold stage are used to regulate the temperature of the quartz capillary balance kettle, the microscope is used to observe the images of water in the quartz capillary balance kettle and the hydrophobic organic matter in the quartz capillary, the camera and the computer are connected by a circuit, the camera is used to collect the images of water and hydrophobic organic matter observed by the microscope, and transmit the image data to the computer.

[0006] The method for high-precision determination of the solubility of hydrophobic organic matter in subcritical water is characterized by comprising the following steps:

[0007] S1: One end of the quartz capillary balance kettle is open and the other end is sealed. After water is injected into the quartz capillary balance kettle using a micro syringe, the water is centrifuged to the bottom seal of the quartz capillary balance kettle using a capillary centrifuge, and then the image of the water in the quartz capillary balance kettle is observed using a microscope, and the volume of the injected water is recorded and calculated using an online image acquisition and detection device and a computer;

[0008] S2: placing the quartz capillary tube with the hydrophobic organic matter absorbed therein into the quartz capillary tube balance kettle treated in step S1, and sealing one end opening of the quartz capillary tube balance kettle with a hydrogen-oxygen flame, and cooling; placing the quartz capillary tube balance kettle horizontally, with the water in the quartz capillary tube balance kettle just covering the two end openings of the quartz capillary tube, and then observing the length image of the hydrophobic organic matter in the quartz capillary tube with a microscope, and measuring the length of the hydrophobic organic matter in the quartz capillary tube with an online image acquisition and detection device and a computer, and calculating the initial volume of the solute hydrophobic organic matter;

[0009] S3: Finally, the quartz capillary balance kettle filled with quartz capillaries is placed on the hot and cold stage of the temperature control device, and the temperature of the quartz capillary balance kettle is increased. During this period, the phase behavior of the hydrophobic organic matter in the quartz capillary is observed, and the change of the residual amount of the hydrophobic organic matter in the quartz capillary is recorded. The temperature T when it is just completely dissolved and the system reaches a uniform state is recorded, and the solubility of the hydrophobic organic matter at this temperature is calculated.

[0010] The manufacturing method of the quartz capillary with hydrophobic organic matter absorbed inside is as follows: a certain length of the quartz capillary is cut, the organic coating on the outer surface thereof is burned off with a hydrogen-oxygen flame to form a transparent visible tube body, and then a certain amount of hydrophobic organic matter is absorbed by the transparent visible quartz capillary, and a small amount of solvent water is absorbed at both ends of the quartz capillary after the organic matter is absorbed, so as to block the organic matter in the quartz capillary.

[0011] Furthermore, as the temperature increases, the solubility of hydrophobic organic matter in water will also gradually increase. Therefore, quartz capillaries loaded with different contents of hydrophobic organic matter can be made, and the quartz capillaries are respectively loaded in a quartz capillary balance kettle, and the above-mentioned operation methods of S1 to S3 are repeated to test the temperature data corresponding to the solubility data of different volumes of hydrophobic organic matter in water.

[0012] The method for high-precision determination of the solubility of hydrophobic organic matter in subcritical water is characterized in that the inner diameter of the quartz capillary balance kettle is 0.250-0.350 mm, and the outer diameter is 0.375-0.665 mm; the inner diameter of the quartz capillary is 0.020-0.080 mm, and the outer diameter is 0.100-0.200 mm; the length of the quartz capillary is less than the length of the quartz capillary balance kettle.

[0013] The method for high-precision determination of the solubility of hydrophobic organic matter in subcritical water is characterized in that in step S3, the temperature range of the quartz capillary equilibrium kettle for heating determination is 100-374°C, and the pressure in the quartz capillary equilibrium kettle is the saturated vapor pressure of the hydrophobic organic matter-water system.

[0014] The method for high-precision determination of the solubility of hydrophobic organic matter in subcritical water is characterized in that in step S3, the total time measured to reach the dissolution equilibrium is 0.5 to 2 days.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. Both the present invention and the previously applied patent CN202110247139.6 are for determining the amount of organic matter dissolved in water. Compared with patent CN202110247139.6, which can measure the solubility data of multiple temperature points with one reactor, the present invention is to address the problem that "under subcritical water temperature and pressure conditions, organic matter will undergo obvious volume changes (absorption of water and thermal expansion)", that is, in order to avoid the influence of volume changes of organic matter under subcritical water temperature and pressure conditions, the test method of "making the organic matter just completely dissolved to obtain the solubility under the temperature and pressure conditions at that moment" is adopted, which can significantly improve the detection accuracy and reduce errors.

[0017] 2. The present invention is based on the basic principle of visual synthesis method, uses quartz capillary as equilibrium reactor, and can measure the high temperature and high pressure system of subcritical water; uses smaller quartz capillary to absorb solute (i.e. hydrophobic organic matter), calculates solubility data, and improves the accuracy of solubility measurement.

[0018] 3. No sampling is required during the measurement process, the equilibrium reactor is small in size and easy to operate, which improves the measurement efficiency of the visual synthesis method and further reduces the experimental cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the quartz capillary and the quartz capillary balance reactor of the present invention;

[0020] Figure 2 The schematic diagram of the structure of the device for measuring the solubility of hydrophobic organic matter in subcritical water according to the present invention. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0022] Example: Control Figure 1-2

[0023] The device for measuring the solubility of hydrophobic organic matter in subcritical water with high precision comprises: a quartz capillary balancing kettle 1, a temperature controller 3, a circulating water system 4, a cold and hot stage 5, a camera 6, a microscope 7 and a computer 8. The quartz capillary balancing kettle 1 is loaded with a quartz capillary 2 whose outer diameter is smaller than the inner diameter of the quartz capillary balancing kettle, the hydrophobic organic matter is absorbed in the quartz capillary 2 and the two ends are open, the quartz capillary balancing kettle 1 is injected with solvent water, and the two ends of the quartz capillary balancing kettle 1 are sealed; The temperature controller 3, the circulating water system 4 and the hot and cold table 5 are used to control the temperature of the quartz capillary balancing kettle; the microscope 7 is used to observe the images of the water in the quartz capillary balancing kettle 1 and the hydrophobic organic matter in the quartz capillary 2; the camera 6 and the computer 8 are connected by a circuit, and the camera 6 is used to collect the images of the water and the hydrophobic organic matter observed by the microscope 7, and transmit the image data to the computer 7; the solvent water in the quartz capillary balancing kettle 1 can just immerse the openings at both ends of the quartz capillary 2.

[0024] The temperature control device uses a hot and cold stage to accurately control the temperature. Furthermore, the device of the present application also includes a micro injection needle, so that solvent water can be injected into the quartz capillary balance kettle through the micro injection needle.

[0025] Comparison Figure 2 In the present application, the device further includes a hot and cold table 5, the quartz capillary balance kettle 1 is placed in the hot and cold table 5, and the temperature of the hot and cold table 5 is adjusted by the temperature controller 3 and the circulating water system 4, so that the quartz capillary balance kettle 1 is at a desired temperature. The hot and cold table 5 is placed under a microscope 7, and the quartz capillary balance kettle 1 can be directly observed through the microscope 7.

[0026] The specific process flow of the present invention for determining the solubility of hydrophobic organic matter in subcritical water comprises the following steps:

[0027] S1: Cut a certain length of quartz capillary 2, burn off the organic coating on its outer surface with hydrogen-oxygen flame to form a transparent visible tube body, then absorb a certain amount of hydrophobic organic matter into the transparent visible quartz capillary 2, and then absorb a small amount of solvent water at both ends of the quartz capillary after absorbing the organic matter to block, so as to prevent the organic matter in the quartz capillary 2 from being squeezed out due to capillary action;

[0028] S2: Separately cut a certain length of a relatively large quartz capillary tube, first weld and seal one end of the quartz capillary tube with a hydrogen-oxygen flame, and leave the other end open to use as a quartz capillary balancing kettle. After injecting water into the quartz capillary balancing kettle with a micro-syringe, use a capillary centrifuge to centrifuge the water to the sealed bottom end of the quartz capillary balancing kettle, then use a microscope to observe the image of the water in the quartz capillary balancing kettle, and use an online image acquisition and detection device and a computer to record and calculate the volume of the injected water;

[0029] The quartz capillary tube with hydrophobic organic matter absorbed therein obtained in step S1 is placed in the quartz capillary tube balancing kettle after the above treatment, and one end opening of the quartz capillary tube balancing kettle is sealed with hydrogen-oxygen flame welding and cooled, thereby obtaining a quartz capillary tube balancing kettle 1 filled with solvent, solute and quartz capillary tube 2. The quartz capillary tube balancing kettle is placed horizontally, and the water in the quartz capillary tube balancing kettle just covers the two end openings of the quartz capillary tube.

[0030] S3: Then, a microscope is used to observe the length image of the hydrophobic organic matter in the quartz capillary, and an online image acquisition detection device and a computer are used to measure the length of the hydrophobic organic matter in the quartz capillary, and the initial volume of the solute hydrophobic organic matter is calculated;

[0031] S4: Finally, the quartz capillary balance kettle filled with quartz capillaries is placed on the hot and cold stage of the temperature control device, and the temperature of the quartz capillary balance kettle is increased. During this period, the phase behavior of the hydrophobic organic matter in the quartz capillary is observed, and the change of the residual amount of the hydrophobic organic matter in the quartz capillary is recorded. The temperature T when it is completely dissolved and the system reaches a uniform state is recorded, and the solubility of the hydrophobic organic matter at this temperature is calculated.

[0032] Furthermore, the inner diameter of the quartz capillary balancing kettle is 0.250-0.350 mm, and the outer diameter is 0.375-0.665 mm; the inner diameter of the quartz capillary is 0.020-0.080 mm, and the outer diameter is 0.100-0.200 mm; the length of the quartz capillary is less than the length of the quartz capillary balancing kettle.

[0033] In the above step S2, the volume of water injected into the quartz capillary balance kettle is calculated. The calculation method can refer to the doctoral dissertation (Micro-capillary balance kettle and in-situ Raman spectroscopy combined to study the expansion law of CO2-petroleum model compounds under simulated geological conditions, author Baker et al., Zhejiang University of Technology). The specific calculation method is: use a camera and a computer to record the image of water in the quartz capillary, divide the image approximately into regular shapes of cones, truncated cones, cylinders and spherical segments, and measure the volume of each image respectively:

[0034] The radius of the cone base r1 and height h1; the radius of the cone base R2, the radius of the top r2 and the height h2; the length of the cylinder l3 and the radius of the base r3; and the height h4 of the spherical segment and the radius r4 of the corresponding sphere, and then according to the liquid density, calculate the volume and mass of the injected water to obtain the initial solvent water volume V 水 The calculation formula is as follows:

[0035]

[0036]

[0037] V 圆柱=πr3 2 l3........................(3)

[0038]

[0039] V 水 =V 圆锥 +V 圆台 +V 圆柱 -V 球缺 .................(5)

[0040] The above formulas (1) to (5) are respectively the volume of a cone, the volume of a truncated cone, the volume of a cylinder, the volume of a spherical segment and the volume of water.

[0041] In step S4, the temperature range of the quartz capillary balance kettle is 100-374°C, and the pressure in the quartz capillary balance kettle is the saturated vapor pressure of the hydrophobic organic matter-water system. In step S4, the total time measured to reach the dissolution equilibrium is 0.5-2 days.

[0042] In the above step S4, when the quartz capillary balance kettle is heated, as the residual amount of hydrophobic organic matter in the quartz capillary gradually decreases, the heating rate can be reduced accordingly. For example, when the residual amount of undissolved hydrophobic organic matter in the quartz capillary is less than 5%, the heating rate is adjusted to 0.5-2°C / h, and the temperature is kept for 1-3 hours for each 0.5-2°C increase in temperature.

[0043] When the hydrophobic organic matter in the quartz capillary is about to reach the end point of dissolving in the solvent water (for example, the remaining amount of undissolved hydrophobic organic matter is less than 5%), the heating rate is reduced accordingly, and the temperature is kept for a certain time every time the temperature is raised to a certain level. In this way, the temperature at which the hydrophobic organic matter is completely dissolved can be monitored more accurately with a small error.

[0044] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as being limited to the specific forms described in the embodiments.

Claims

1. A method for high-precision determination of the solubility of hydrophobic organic matter in subcritical water, characterized in that The following steps are involved: S1: One end of the quartz capillary balance kettle is open and the other end is sealed. After water is injected into the quartz capillary balance kettle using a micro syringe, the water is centrifuged to the bottom seal of the quartz capillary balance kettle using a capillary centrifuge, and then the image of the water in the quartz capillary balance kettle is observed using a microscope, and the volume of the injected water is recorded and calculated using an online image acquisition and detection device and a computer; S2: placing the quartz capillary tube with the hydrophobic organic matter absorbed therein into the quartz capillary tube balance kettle treated in step S1, and sealing one end opening of the quartz capillary tube balance kettle with a hydrogen-oxygen flame, and cooling; placing the quartz capillary tube balance kettle horizontally, with the water in the quartz capillary tube balance kettle just covering the two end openings of the quartz capillary tube, and then observing the length image of the hydrophobic organic matter in the quartz capillary tube with a microscope, and measuring the length of the hydrophobic organic matter in the quartz capillary tube with an online image acquisition and detection device and a computer, and calculating the initial volume of the solute hydrophobic organic matter; S3: Finally, the quartz capillary balance kettle filled with quartz capillaries is placed on the hot and cold stage of the temperature control device, and the temperature of the quartz capillary balance kettle is increased. During this period, the phase behavior of the hydrophobic organic matter in the quartz capillary is observed, and the change of the residual amount of the hydrophobic organic matter in the quartz capillary is recorded. The temperature T when the hydrophobic organic matter is completely dissolved and the system reaches a uniform state is recorded, and the solubility of the hydrophobic organic matter at this temperature is calculated; In step S3, the temperature range of the quartz capillary balance kettle temperature rise measurement is 100-374°C, and the pressure in the quartz capillary balance kettle is the saturated vapor pressure of the hydrophobic organic matter-water system; When the quartz capillary balance kettle is heated, as the residual amount of hydrophobic organic matter in the quartz capillary gradually decreases, the heating rate is correspondingly reduced. When the residual amount of undissolved hydrophobic organic matter in the quartz capillary is less than 5%, the heating rate is adjusted to 0.5-2°C / h, and the temperature is kept for 1-3 hours for each 0.5-2°C increase in temperature; The inner diameter of the quartz capillary balancing kettle is 0.250-0.350 mm, and the outer diameter is 0.375-0.665 mm; the inner diameter of the quartz capillary is 0.020-0.080 mm, and the outer diameter is 0.100-0.200 mm; the length of the quartz capillary is less than the length of the quartz capillary balancing kettle; In step S2, the method for making the quartz capillary tube with hydrophobic organic matter absorbed inside is as follows: a certain length of quartz capillary tube is cut, and the organic coating on the outer surface thereof is burned off with a hydrogen-oxygen flame to form a transparent visible tube body, and then a certain amount of hydrophobic organic matter is absorbed by the transparent visible quartz capillary tube, and a small amount of solvent water is absorbed at both ends of the quartz capillary tube after the organic matter is absorbed, so as to block the organic matter in the quartz capillary tube.

2. A method for high-precision determination of the solubility of hydrophobic organic matter in subcritical water as claimed in claim 1, characterized in that In step S3, the total time measured to reach dissolution equilibrium is 0.5 to 2 days.

3. The device used in the method for high-precision determination of solubility of hydrophobic organic matter in subcritical water according to claim 1 is characterized in that The invention comprises a quartz capillary balancing kettle (1), a temperature controller (3), a circulating water system (4), a hot and cold stage (5), a camera (6), a microscope (7) and a computer (8); wherein the quartz capillary balancing kettle (1) is loaded with a quartz capillary (2) whose outer diameter is smaller than its inner diameter; the quartz capillary (2) absorbs hydrophobic organic matter and has two open ends; the quartz capillary balancing kettle (1) is injected with solvent water and has two sealed ends; the temperature controller, the circulating water system and the hot and cold stage are used to control the temperature of the quartz capillary balancing kettle (1); the microscope is used to observe images of water in the quartz capillary balancing kettle (1) and hydrophobic organic matter in the quartz capillary (2); the camera and the computer are connected by a circuit; the camera is used to collect images of water and hydrophobic organic matter observed by the microscope and transmit the image data to the computer.

Images