Vinyl chloride standard solution preparation device and preparation method

Abstract

The invention discloses a vinyl chloride standard solution preparation device and a vinyl chloride standard solution preparation method. The device comprises a vinyl chloride gas source, a vinyl chloride gas source pressure reducing valve, a gas bag inlet valve of a buffer gas bag, a gas bag outlet valve of the buffer gas bag, a gas inlet pipeline of an absorption device, a gas outlet pipeline of the absorption device, a suck-back prevention gas inlet of a suck-back prevention device, a suck-back prevention gas outlet of the suck-back prevention device and a gas path inlet of a gas sampling device. A gas path outlet and an exhaust port of the gas sampling device are sequentially connected through a silica gel hose, and the exhaust port is connected with the atmosphere through an organic gas absorption tank; the weighing device is used for weighing the absorption device filled with methanol, and the temperature control device used for keeping the temperature of liquid in the gas absorption bottle is arranged outside the gas absorption bottle of the absorption device. According to the invention, preparation is carried out through a weight-weight method, and a preparation value is taken as a standard value, so that the accuracy of the quantity value is ensured; and the uncertainty of manual control of the gas sampling amount and the risk of personnel operation contact are reduced to the greatest extent.

Description

Technical Field

[0001] The invention belongs to the technical field of analyzing materials by weighing methods, and specifically relates to a device and a method for preparing a vinyl chloride standard solution. Background Art

[0002] Polyvinyl chloride (PVC) resin is widely used in industry, agriculture, construction, daily necessities, packaging and electricity due to its flame retardancy, chemical corrosion resistance, wear resistance, excellent electrical insulation and high mechanical strength. Vinyl chloride, as the main comonomer of polyvinyl chloride, has a huge output and is an important raw material in the plastics industry. However, vinyl chloride is classified as a class I carcinogen, with liver damage as the main manifestation. If it cannot be properly discharged, it is very likely to cause serious environmental pollution and waste of resources.

[0004] The boiling point of vinyl chloride under normal pressure is -13.4℃, and it is gaseous at room temperature. Therefore, there are great difficulties in the preparation process. Literature reports that the preparation of solutions for gaseous components currently uses syringes and solvent closed absorption methods to transfer gaseous vinyl chloride to liquid solvents. This preparation method is greatly affected by human and environmental factors, the preparation amount is inaccurate, and vinyl chloride is extremely volatile, so operators have a certain risk of exposure. Summary of the invention

[0005] In view of the problems existing in the background technology, the present invention provides a device for preparing a vinyl chloride standard solution, and the technical scheme includes: a vinyl chloride gas source, a buffer air bag, an absorption device, a temperature control device, an anti-backflow device, a weighing device and a gas sampling device; wherein, the vinyl chloride gas source, the vinyl chloride gas source pressure reducing valve, the air bag inlet valve of the buffer air bag, the air bag outlet valve of the buffer air bag, the air inlet pipeline of the absorption device, the air outlet pipeline of the absorption device, the anti-backflow air inlet of the anti-backflow device, the anti-backflow air outlet of the anti-backflow device, the gas path inlet of the gas sampling device, the gas path outlet and the exhaust port of the gas sampling device are connected in sequence through a silicone hose, and the exhaust port is connected to the atmosphere through an organic gas absorption tank; the weighing device is used to weigh the absorption device filled with methanol, and the temperature control device for maintaining the temperature of the liquid in the gas absorption bottle is arranged outside the gas absorption bottle of the absorption device.

[0006] The absorption device includes a gas absorption bottle, a bottle cap, a silicone plug, an air inlet pipeline and an air outlet pipeline, wherein the gas absorption bottle is made of glass with scales, and the length of the air inlet pipeline passing through the bottle cap reaches the bottom of the gas absorption bottle; the gas absorption bottle contains methanol solution, and the air outlet pipeline is installed on the bottle cap so as to be connected with the gas absorption bottle; the silicone plug is used to block the air inlet of the air inlet pipeline and the air outlet of the air outlet pipeline.

[0007] The anti-backflow device comprises: an absorption bottle with color-changing silica gel inside.

[0008] The weighing device comprises: a balance and a wind shield, wherein the wind shield is arranged outside the balance and a closed door is arranged on the side of the wind shield.

[0009] The present invention also provides a method for preparing a vinyl chloride standard solution, and the technical solution comprises:

[0010] Step 1, using a weighing device to weigh the empty absorption bottle with a silicone stopper;

[0011] Step 2, after adding methanol solvent into the absorption bottle, cover the silicone plug, and weigh the weight using a weighing device;

[0012] Step 3: Use silicone hose to connect the components of each device and ensure that the entire device is in a closed state, set the temperature parameters of the temperature control device, set the flow parameters and time parameters of the gas sampling device, and then turn on the temperature control device.

[0013] Step 4: Ensure that the cushion air bag is in a vacuum dry state, ensure that the air bag outlet valve is closed, open the air bag inlet valve and the vinyl chloride gas source pressure reducing valve; fill the air bag with vinyl chloride gas; then close the air bag inlet valve and the vinyl chloride gas source pressure reducing valve;

[0014] Step 5, record the indoor ambient temperature, open the air bag outlet valve after setting the appropriate flow rate and time in the gas sampling device; then open the gas sampling device, and the flow control system in the gas sampling device controls the flow rate through the flow parameters; finally, immediately open the air bag inlet valve, the vinyl chloride gas source pressure reducing valve, and the air bag outlet valve at the same time to prepare the standard solution; the preparation is completed when the set time parameter is reached;

[0015] Step 6: After the preparation is completed, close the air bag outlet valve, air bag inlet valve and vinyl chloride gas source pressure reducing valve in sequence, immediately plug the absorption bottle with a silicone plug, and use a weighing device to weigh;

[0016] Step 7: Record the standard concentration value in the gas absorption bottle and transfer it to a sealed reagent bottle for storage.

[0017] The calculation method of the standard value of the concentration in the gas absorption bottle is:

[0018] Calculate the volume of solvent methanol according to the formula:

[0019] ρ t =ρ 0 ×(1-a×(t-20))

[0020]

[0021] Where: t ——Methanol density at actual temperature, g / cm 3

[0022] ρ 0 ——Density of methanol at 20℃, g / cm 3

[0023] a——temperature coefficient, / ℃

[0024] m——the mass of methanol at actual temperature, g

[0025] V t ——The volume of methanol at actual temperature, mL;

[0026] Calculate the concentration standard value of the solution according to the formula

[0027]

[0028] Where: C——concentration of solution, μg / mL;

[0029] m——mass of raw materials, g;

[0030] V——Constant volume of the solution, mL.

[0031] The temperature range set by the temperature control device is -40°C to -20°C.

[0032] The solution stored in the sealed reagent bottle needs to be prepared and used immediately, and diluted to the target concentration according to the usage.

[0033] The beneficial effects of the present invention are:

[0034] 1. The present invention is prepared by weight-weight method, and the prepared value is used as the standard value, thereby ensuring the accuracy of the measurement value.

[0035] 2. Minimize the uncertainty of manually controlling the gas injection volume and the risk of human operation exposure.

[0036] 3. The waste gas generated by the present invention is discharged into the atmosphere after being treated, thus reducing the possibility of environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The present invention is a schematic structural diagram of a broad embodiment of a device for preparing a vinyl chloride standard solution.

[0038] Figure 2 A schematic diagram of a weighing process of an absorption bottle provided in a broad embodiment of the present invention.

[0039] Figure 3 It is the standard curve of the vinyl chloride standard solution prepared according to the specific implementation method in the present invention.

[0040] Among them, 1-vinyl chloride gas source, 2-buffer air bag, 3-absorption device, 4-temperature control device, 5-anti-backflow device, 6-gas sampling device, 7-weighing device, a1-vinyl chloride gas source pressure reducing valve, b1-air bag inlet valve, b2-air bag outlet valve. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0042] like Figure 1 The broad embodiment of the present invention shown comprises: a vinyl chloride gas source 1, a buffer air bag 2, an absorption device 3, a temperature control device 4, an anti-backflow device 5, a weighing device 7 and a gas sampling device 6; wherein, the vinyl chloride gas source 1, the vinyl chloride gas source pressure reducing valve a1, the air bag inlet valve b1 of the buffer air bag 2, the air bag outlet valve b2 of the buffer air bag 2, the air inlet pipeline of the absorption device 3, the air outlet pipeline of the absorption device 3, the anti-backflow air inlet of the anti-backflow device 5, the anti-backflow air outlet of the anti-backflow device 5, the air path inlet of the gas sampling device 6, the air path outlet and the exhaust port of the gas sampling device 6 are sequentially connected through a silicone hose, and the exhaust port is connected to the atmosphere through an organic gas absorption tank, so that the whole process is guaranteed to be in a good airtight state; the weighing device 7 is used to weigh the absorption device 3 filled with methanol, and the temperature control device 4 for maintaining the temperature of the liquid in the gas absorption bottle is arranged outside the gas absorption bottle of the absorption device 3.

[0043] The absorption device 3 includes a gas absorption bottle, a bottle cap, a silicone plug, an air inlet pipe and an air outlet pipe, wherein the gas absorption bottle is made of glass and has a scale, and the length of the air inlet pipe passing through the bottle cap reaches the bottom of the gas absorption bottle; the gas absorption bottle contains methanol solution, and the air outlet pipe is installed on the bottle cap so as to be connected with the gas absorption bottle; the silicone plug is used to block the air inlet of the air inlet pipe and the air outlet of the air outlet pipe.

[0044] The temperature control device 4 is a refrigeration and heating integrated temperature control device capable of controlling a temperature in the range of -40°C to 100°C. In this embodiment, a DHYF-4002 temperature control device 4 is specifically used.

[0045] The anti-backflow device 5 includes: an absorption bottle with color-changing silica gel inside, including an anti-backflow air inlet and an anti-backflow air outlet, the anti-backflow air inlet is connected to the absorption device through a silicone hose, and the anti-backflow air outlet is connected to the gas sampling device through a silicone hose.

[0046] The gas sampling device 6 needs to be calibrated and traceable to SI units, including: a shell and a temperature sensor, a pressure sensor, a timing device, a flow sensor, a flow control system, a gas path inlet, a gas path outlet and a data display screen installed on the shell; the gas sampling device 6 can collect gas stably and evenly by adjusting the gas flow rate and sampling time, and control the gas flow rate in the range of (1mL / min-500mL / min), and can control the gas flow through the timing and quantitative function. The gas path inlet is connected to the anti-backflow device through a silicone hose, and the gas path outlet is discharged through the vent; in this embodiment, a Laoying 2061 type gas sampling device is specifically used.

[0047] The weighing device 7 comprises: a large-scale balance (with a measuring range of 0.0001g-5100g and an accuracy of 0.0001g), and a windshield, which is arranged outside the balance and has a closed door on the side thereof.

[0048] The operation of the broad embodiment includes the following steps:

[0049] a. Prepare the vinyl chloride gas source 1, buffer gas bag 2, absorption device 3, temperature control device 4, anti-backflow device 5, weighing device 7, gas sampling device 6 and several silicone hoses. The exhaust port of the sampling device enters the organic gas absorption tank through the pipeline, and is discharged to the atmosphere after being processed by the organic gas absorption tank;

[0050] b. Use a weighing device to weigh the empty absorption bottle with a silicone stopper;

[0051] c. After adding methanol solvent to the absorption bottle, cover the silica gel plug and weigh it using a weighing device;

[0052] d. Use a silicone hose to connect the various components of the device and ensure that the entire device is in a closed state, set the parameters of the temperature control device 4 (temperature parameters) and the gas sampling device 6 (flow parameters and time parameters), and then turn on the temperature control device 4. In this embodiment, the temperature parameter range of the temperature control device 4 is -40°C to -20°C;

[0053] e. Ensure that the buffer air bag is in a vacuum dry state, ensure that the air bag outlet valve b2 on the side of the buffer air bag connected to the absorption bottle is closed, open the air bag inlet valve b1 and open the vinyl chloride gas source pressure reducing valve a1; fill the air bag with vinyl chloride gas; then close the air bag inlet valve b1 and the vinyl chloride gas source pressure reducing valve a1;

[0054] f. Record the indoor ambient temperature displayed on the gas sampling device 6, and open the air bag outlet valve b2 after setting the appropriate flow rate and time on the gas sampling device; then open the gas sampling device 6, which calculates the flow rate through the internal flow sensor (flow meter) and controls the flow rate through the flow control system; finally, immediately open the air bag inlet valve b1, the vinyl chloride gas source pressure reducing valve a1, and the air bag outlet valve b2 at the same time; prepare the standard solution; when the time parameter set by the gas sampling device 6 is reached, the preparation ends automatically;

[0055] g. After the preparation is completed, close the air bag outlet valve b2, the air bag inlet valve b1 and the vinyl chloride gas source pressure reducing valve a1 in turn, immediately plug the absorption bottle with a silicone plug, and use a weighing device to weigh.

[0056] h. Calculate the volume of solvent methanol according to the formula:

[0057] ρ t =ρ 0 ×(1-a×(t-20))

[0058]

[0059] Where: t ——Methanol density at actual temperature, g / cm 3

[0060] ρ 0 ——Density of methanol at 20℃, g / cm 3

[0061] a——temperature coefficient, / ℃

[0062] m——the mass of methanol at actual temperature, g

[0063] V t ——The volume of methanol at actual temperature, mL;

[0064] i. Calculate the concentration standard value of the solution according to the formula

[0065]

[0066] Where: C——concentration of solution, μg / mL;

[0067] m——mass of raw materials, g;

[0068] V——Constant volume of the solution, mL.

[0069] j. Record the standard concentration value in the gas absorption bottle and transfer it to a sealed reagent bottle for storage;

[0070] k. The prepared solution must be used immediately and can be diluted to the target concentration according to usage.

[0071] The effect of the present invention is further described below using a specific implementation method:

[0072] 1. Preparation of standard solution

[0073] Place the vinyl chloride gas source 1, the buffer gas bag 2, the absorption device 3, the temperature control device 4, the anti-backflow device 5, the weighing device 7, the gas sampling device 6, several silicone hoses and the organic gas absorption tank according to the test process;

[0074] (2) After the silicone stopper is closed, weigh the empty absorption bottle and record the weight; add 125 mL of methanol solvent, make sure the silicone stopper is closed, weigh again and record the weight;

[0075] (3) Use a silicone hose to connect the vinyl chloride gas source 1, the buffer gas bag 2, the absorption device 3, the temperature control device 4, the anti-backflow device 5, the gas sampling device 6 and the organic gas absorption tank, and check the airtight state; set the temperature of the temperature control device 4 to -20°C; set the flow rate in the gas sampling device 6 to 25 mL / min and the time to 1 min;

[0076] (4) Ensure that the buffer air bag is in a vacuum dry state, ensure that the air bag outlet valve b2 on the side of the buffer air bag connected to the absorption bottle is closed, open the air bag inlet valve b1 and open the vinyl chloride gas source pressure reducing valve a1; fill the air bag with vinyl chloride gas; then close the air bag inlet valve b1 and the vinyl chloride gas source pressure reducing valve a1;

[0077] (5) When the 1 minute set by the gas sampling device 6 is reached, the preparation is automatically completed; after the preparation is completed, the air bag outlet valve b2, the air bag inlet valve b1 and the vinyl chloride gas source pressure reducing valve a1 are closed in sequence, and the absorption bottle is immediately plugged with a silicone plug and weighed.

[0078] (6) taking a solution sample into a sampling vial and testing it on a gas chromatograph;

[0079] (7) Repeat steps (3) to (6) three times to prepare three solution samples for parallel comparison;

[0080] (8) Table 1 Original weighing record (Mass 1 is the mass of the empty absorption bottle; Mass 2 is the mass of the empty absorption bottle + solvent; Mass 3 is the mass of the empty absorption bottle + solvent + vinyl chloride)

[0081]

[0082] (9) Table 2 Test raw data

[0083]

[0084] 2. Preparation of standard curve

[0085] (1) Using sample 1 in Example 1 as the mother liquor, 8 mL, 4 mL, 1.6 mL, 1.3 mL, and 0.8 mL of the mother liquor were taken respectively, and the volume was fixed to 100 mL with methanol solvent and mixed to obtain 5000 μg / mL, 2500 μg / mL, 1000 μg / mL, 800 μg / mL, and 500 μg / mL vinyl chloride standard solutions;

[0086] (2) Take the diluted solutions and test them on the machine;

[0087] like Figure 3 And the linear test raw data shown in Table 3

[0088]

[0089] The preparation results show that the prepared standard solution has good accuracy and repeatability. The standard curve prepared after dilution has good linearity, which can meet the detection needs under different conditions and has broad application prospects in environmental monitoring and quality control.

Claims

1. A device for preparing a vinyl chloride standard solution, characterized in that: include: A vinyl chloride gas source (1), a buffer gas bag (2), an absorption device (3), a temperature control device (4), an anti-backflow device (5), a weighing device (7) and a gas sampling device (6); wherein the vinyl chloride gas source (1), a vinyl chloride gas source pressure reducing valve (a1), an air bag inlet valve (b1) of the buffer gas bag (2), an air bag outlet valve (b2) of the buffer gas bag (2), an air inlet pipeline of the absorption device (3), an air outlet pipeline of the absorption device (3), an anti-backflow air inlet of the anti-backflow device (5), an anti-backflow air outlet of the anti-backflow device (5), an air path inlet of the gas sampling device (6), an air path outlet of the gas sampling device (6) and an exhaust port are sequentially connected via a silicone hose, and the exhaust port is connected to the atmosphere via an organic gas absorption tank; the weighing device (7) is used to weigh the absorption device (3) filled with methanol, and the temperature control device (4) for maintaining the temperature of the liquid in the gas absorption bottle is arranged outside the gas absorption bottle of the absorption device (3).

2. The device for preparing a vinyl chloride standard solution according to claim 1, characterized in that: The absorption device (3) comprises a gas absorption bottle, a bottle cap, a silicone plug, an air inlet pipeline and an air outlet pipeline, wherein the gas absorption bottle is made of glass with scales, and the length of the air inlet pipeline passing through the bottle cap reaches the bottom of the gas absorption bottle; the gas absorption bottle contains methanol solution, and the air outlet pipeline is installed on the bottle cap so as to be connected with the gas absorption bottle; the silicone plug is used to block the air inlet of the air inlet pipeline and the air outlet of the air outlet pipeline.

3. The device for preparing a vinyl chloride standard solution according to claim 1, characterized in that: The anti-backflow device (5) comprises: an absorption bottle with color-changing silica gel inside.

4. The device for preparing a vinyl chloride standard solution according to claim 1, characterized in that: The weighing device (7) comprises: a balance and a wind shield, wherein the wind shield is arranged outside the balance and a sealed door is arranged on the side of the wind shield.

5. A method for preparing a vinyl chloride standard solution preparation device as claimed in claim 1, characterized in that: include: Step 1, using a weighing device to weigh the empty absorption bottle with a silicone stopper; Step 2, after adding methanol solvent into the absorption bottle, cover the silicone plug, and weigh the weight using a weighing device; Step 3: Use silicone hose to connect the components of each device and ensure that the entire device is in a closed state, set the temperature parameters of the temperature control device, set the flow parameters and time parameters of the gas sampling device, and then turn on the temperature control device; Step 4: Ensure that the cushion air bag is in a vacuum dry state, ensure that the air bag outlet valve is closed, open the air bag inlet valve and the vinyl chloride gas source pressure reducing valve; fill the air bag with vinyl chloride gas; then close the air bag inlet valve and the vinyl chloride gas source pressure reducing valve; Step 5, record the indoor ambient temperature, open the air bag outlet valve after setting the appropriate flow rate and time in the gas sampling device; then open the gas sampling device, and the flow control system in the gas sampling device controls the flow rate through the flow parameters; finally, immediately open the air bag inlet valve, the vinyl chloride gas source pressure reducing valve, and the air bag outlet valve at the same time to prepare the standard solution; the preparation is completed when the set time parameter is reached; Step 6: After the preparation is completed, close the air bag outlet valve, air bag inlet valve and vinyl chloride gas source pressure reducing valve in sequence, immediately plug the absorption bottle with a silicone plug, and use a weighing device to weigh; Step 7: Record the standard concentration value in the gas absorption bottle and transfer it to a sealed reagent bottle for storage.

6. The method for preparing a vinyl chloride standard solution according to claim 5, wherein the concentration standard value in the gas absorption bottle is calculated as follows: Calculate the volume of the solvent methanol: r t =ρ0×(1-a×(t-20)) Where: t ——Methanol density at actual temperature, g / cm 3 ρ0——density of methanol at 20℃, g / cm 3 a——temperature coefficient, / ℃ m——the mass of methanol at actual temperature, g V t ——The volume of methanol at actual temperature, mL; Calculate the standard value of the solution concentration: Where: C——concentration of solution, μg / mL; m——mass of raw materials, g; V——Constant volume of the solution, mL.

7. The method for preparing a vinyl chloride standard solution according to claim 5, wherein the temperature range set by the temperature control device is -40°C to -20°C.

8. The method for preparing a vinyl chloride standard solution according to claim 5, wherein the solution stored in the sealed reagent bottle needs to be prepared and used immediately, and is diluted to a target concentration according to usage.

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