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Detecting Chlorine Gases New Method

Chlorine gas, a yellow-green toxic gas, enters the body through the respiratory tract and dissolves in water in the mucous membranes, upper respiratory tract, lungs, skin, and other organs. Hangwei is a professional gas detectors manufacturer in China, this post we will share the knowledge of detecting chlorine gases new method.

Conventional methods for measuring gas chlorine content include methyl orange spectrophotometry and iodine amount. Orange methyl Spectrophotometric Method oxidizes potassium bromide into bromine in the acidic solution of potassium bromide-methyl orange by chlorine gas, then tests it by bromine color development on methyl orange. Iodometric Method oxidizes iodide by chlorine gas to generate iodine, then tests it by titration of standard solution of sodium thiosulfate.

These two methods are time-consuming, require a variety of chemical reagents, and are easily affected by ambient temperature and reaction time, resulting in poor reproducibility and accuracy.

Ion chromatography uses an improved conductivity detector behind an ion exchange resin column to continuously detect chromatographically separated ions. It has good selectivity and high accuracy for inorganic anions and avoids ambient temperature, reaction time, and other factors.

The method is well known for determining the inorganic anion chloride, but indirect chloride determination in gases has not been reported.

Invention Contents

Present invention aims to provide a simple and fast method for gas chlorine detection.

The present invention is realized by using ion chromatography, which has good selectivity for inorganic anions, as a testing means, adopting a fixed volume sampling scheme, combining sodium hydroxide absorption solution absorption through dual gas circuit systems with controlled gas circuit conversion, and using a valve combination scheme to realize fixed volume sampling, gas transfer and absorption, and chlorine gas conversion. The gas chlorine is calculated from the chloride ion concentration.

The present invention relates to a gas chlorine detection method that includes sample collection and processing, testing, and calculation.

Quantitative gas sampling with a constant volume sampling bottle; chlorine gas conversion to chloride ions with a sodium hydroxide absorbent;

Testing and calculation: ion chromatography and formula (1) to calculate gas chlorine content.

Where: C0—gas chlorine content, mol/mol;

Chloride ion content in sample solution, mg/L;

V1; sample solution volume, mL;

Volume of chlorine sampling tube, L;

L/mol gas volume at sampling temperature and pressure.

This invention relates to a method of detecting chlorine content in a gas, which includes sample collection and processing, testing, and calculation. The sample processing uses high purity nitrogen, multi-stage absorption, and 0.1 to 0.2 mol/L sodium hydroxide absorbent solution.

The present invention describes a gas chlorine detection method that includes sample collection and processing, testing, and calculation: The sample processing process carrier gas flow rate is 100–500 mL/min.

The present invention is a gas chlorine detection method with simple operation steps, good repeatability, and high accuracy. Suitable for detecting chlorine content in gases (1-1000 μmol/mol), including atmospheric levels.

Drawing descriptions

FIG. 1 Schematic of the chlorine gas ionization conversion device of the present invention.

FIG. 2 Chlorine gas sampling flow chart for the invention’s chlorine gas ionization conversion device.

Figure 3 Chlorine ionization conversion device pipeline blowing flow chart of the present invention.

Figure 4: Chlorine ionization conversion device absorption conversion flow chart in this invention.

Figure 5 sodium hydroxide absorption solution blank ion chromatogram

Figure 6: Ion chromatogram of 1 μmol/mol chlorine gas that was absorbed and converted.

1 gas to measure, 2 pressure reducing valve for gas to measure, 3-sampling valve, 4-carrier gas, 5-carrier gas valve, Control assembly 6-flow, 7-, 8-, and 9-sampling bottle front and rear valves Control valve 10 parallel, 11th parallel at absorption end, 12-vacuum release valve, 13-washer gas bottle, 15-absorption bottle, 14-absorption valve

Certain examples

The following details specific embodiments but does not limit the invention.

One embodiment

The following method is used to collect a gas sample (1 μmol/mol) from a cylinder.

In FIG. 1, the critical flow venturi nozzle (flow control assembly 6) is connected to the gas to be measured, the carrier gas, the sampling bottle 8, and the parallel control valve 10, and the four-way valve 11 at the parallel point of the absorption end is connected to the absorption bottle 15, tail gas absorption bottle 13, sampling bottle 8, and parallel control valve 10. The sampling bottle 8 is a 1000 ml fixed volume sampling bottle, the absorption bottle 15 is three 25 ml multi-glass plate absorption tubes in series, and the gas washing bottle 13 is 500 mL.

Each multi-glass plate absorption tube 15 holds 15 ml (column height 120 mm) of sodium hydroxide at 0.1 mol/L, and the gas washing bottle 13 holds 250 ml at 1 mol/L.

Close the carrier gas valve 5, parallel control valve 10, and absorption valve 14, open the gas to be measured pressure reducing valve 2, sampling valve 3, sampling bottle before the valve 7 and sampling bottle after the valve 9, and venting valve 12 (sampling pipeline structure as shown in Figure 2 arrow), adjust the outlet pressure of the pressure reducing valve 2 to 0.25MPa, and set the critical flow venturi nozzle to 500mL/min. Complete the sampling by closing the gas to be measured, pressure reducing valve 2, sampling valve 3, and sampling bottle before valve 7, the tube pressure, and atmospheric pressure equilibrium. Close the sampling bottle after valve 9 and venting valve 12.

Complete sampling, open carrier gas valve 5, parallel control valve 10, and venting valve 12, blow pipeline for 5 min.

After pipeline blowing, close parallel control valve 10, air release valve 12, sampling bottle before valve 7, sampling bottle after valve 9, and absorption valve 14, chlorine gas conversion. Adjust pressure reducing valve outlet pressure to 0.25MPa, critical flow venturi nozzle gas flow control to 500mL/min. 15min absorption, close carrier gas 4, carrier gas valve 5, sampling bottle before valve 7, sampling bottle after valve 9, and absorption valve 14. To 100mL, mix three bottles of absorbing solution with distilled water.

2. Formulating chloride ion series standard solution

In six 100mL volumetric flasks, add 0.1mL, 0.2mL, 0.3mL, 0.4mL, 0.5mL, and 0.6mL standard value of 10mg/L chlorine ions standard solution, fixed, shaking, to get 0.01, 0.02, 0.03, 0.04, 0.05, and 0.06mg/L chlorine ions solutions. Standard answer.

3.Test:

Ion chromatography testing procedures:

Ion chromatography column: SKgel Super IC-Anion HS

The conductivity detector

Column temperature: 40℃

Mobile phase: carbonate solution (116.50mg anhydrous sodium carbonate and 630.09mg sodium bicarbonate, dissolved in water and diluted to 1000mL, shaking well).

Fluid flow: 1.0mL/min

Injection volume: 30μL

Sample test and standard curve plotting:

Add 30μL of each chloride ion standard solution to the ion chromatograph, then plot the peak area against the corresponding chloride ion content (mg/L). Measure the sample using standard series operating conditions, calculate the chlorine ion content (CCl-) from the standard curve, and calculate the chlorine content in the standard gas (1.02 μmol/mol) using formula (1).

The chlorine content in the standard gas was tested six times using methyl orange spectrophotometry, iodine quantity method, and ion chromatography. The repeatability was calculated and compared to the standard error. Test results showed that the present invention’s repeatability in determining gas chlorine content was 1.2% and the relative error of measurement was 2%, while the methyl orange spectrophotometric method was 9.2% and 10.1% and the iodometric method was 8.6% and 9.8%.

Example 2

The following method is used to collect a gas sample (nominal content: 500 μmol/mol) in a cylinder.

FIG. 1 shows the gas treatment device’s structure, which is the same as Example 1. Each multi-glass plate absorption tube 15 is injected with 15 ml (column height of 120 mm) of sodium hydroxide at 0.15 mol/L, the critical flow Venturi nozzle gas flow rate is 300 mL/min during sampling and absorption conversion, and the sampling vial 8 is a 100 ml fixed-volume sampling vial. The chloride ion standard solutions were 0.1, 0.5, 1.0, 3.0, 5.0, 7.0 mg/L. The process of sampling, absorption conversion, and test calculation was identical to Example 1, and the chlorine content in the standard gas was calculated as 494 μmol/mol using Equation (1).

Methyl orange spectrophotometry, iodine quantity method, and ion chromatography were used to test the standard gas chlorine content six times, calculate repeatability, and compare error to the standard value. Test results showed that the present invention’s repeatability in determining gas chlorine content was 0.7% and its relative error was 1.2%, while the methyl orange spectrophotometric method was 8.1% and 9.4% and the iodometric method was 8.3% and 9.2%.

Example 3

Here is a method for collecting a gas sample (nominal content: 1000 μmol/mol) in a cylinder. FIG. 1 shows the gas treatment device structure. Each of six series-connected 25 ml multi-glass plate absorption tubes 15 is filled with 10 ml (column height 80 mm) of 0.2 mol/L sodium hydroxide. In the sampling and absorption conversion process, the critical flow Venturi nozzle gas flow rate is controlled at 100 mL/min, the sampling bottle is a 100 ml fixed-volume sampling bottle, and the Chloride ion series standard solution concentration is 0.1, 0.5, 1.0, 3.0, 5.0, 7.0 mg/L. Sampling, absorption conversion, and test calculation were identical to Example 1, and the standard gas chlorine content was calculated as 990 μmol/mol using Equation (1).

For six tests, methyl orange spectrophotometry, iodometry, and ion chromatography measured the chlorine content in the standard gas, calculated repeatability, and compared the error to the standard value. The invention had a 0.5% repeatability and 1% relative error in determining chlorine in gas, while the methyl orange spectrophotometric method had 7.2% and 9.1%, and the iodometric method had 7.6% and 9.3%.

Experiments with different chlorine treatment conditions resulted in less than 2% measurement error and repeatability when the chlorine content was between (1~1000) μmol/mol.

For more information, please visit: https://patents.google.com/patent/CN108152396A/en

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