HG/T 2024-1991 Determination of scale inhibition performance of water treatment agents - Bubble method
Some standard content:
Chemical Industry Standard of the People's Republic of China
HG/T2024-91
Measurement Method for Scale Inhibition Performance of Water Treatment Agents
Published on June 27, 1991
Published by the Ministry of Chemical Industry of the People's Republic of China and implemented on January 1, 1992
Chemical Industry Standard of the People's Republic of China
Measurement Method for Scale Inhibition Performance of Water Treatment Agents
1 Subject Content and Scope of Application
HG/T2024-91bzxz.net
This standard specifies the laboratory method for determining the scale inhibition performance of water treatment agents to inhibit the precipitation of calcium carbonate scale by bubbling method. In principle, this standard is also applicable to the determination of the scale inhibition performance of water treatment agents to inhibit the precipitation of strontium carbonate or barium carbonate scale. 2 Reference standards
Preparation of standard solutions for titration analysis (volume analysis) of chemical reagents GB601
Preparation of standard solutions for determination of impurities
GB602 Chemical reagents
GB603 Preparation of preparations and products used in test methods of chemical reagents 3 Method summary
Scaling in cooling water is caused by the decomposition of calcium bicarbonate in water under heating and aeration conditions to form insoluble calcium carbonate scale. The reaction formula can be expressed as:
Ca(HCO,)2CaCOs+CO,++H2O
. (1)
This method uses prepared water containing Ca(HCOs)2 and water treatment agents to prepare a test solution (simulated cooling water). In order to simulate the two processes of cooling water being heated in the heat exchanger and being degassed in the cooling tower, this method blows a certain flow of air into the test solution at an elevated temperature to take away the carbon dioxide therein, so that the equilibrium of reaction formula (1) moves to the right, prompting calcium bicarbonate to decompose into calcium carbonate at an accelerated rate, and the test solution quickly reaches its natural equilibrium pH. Then the stable concentration of calcium ions in the test solution is determined. The greater the stable concentration of calcium ions, the better the scale inhibition performance of the water treatment agent.
4 Reagents and Materials
In the test method, except for special provisions, only analytical reagents and distilled water or water of equal purity should be used. The standard solutions, preparations and products required in the test shall be prepared in accordance with the provisions of GB601, GB602 and GB603 unless otherwise specified.
4.1 Potassium hydroxide (GB2306): 200g/L solution. 4.2 Disodium ethylenediaminetetraacetate (EDTA) (GB1401): c (EDTA) = 0.01 mol/L standard solution. 4.3 Hydrochloric acid (GB622): c (HCI) = 0.1 mol/L standard solution. 4.4 Calcein-phenol mixed indicator: weigh 0.20g calcein, 0.070g phenolic acid (GB10729), put in a glass mortar, add 20g potassium nitride (GB646) dried at 120℃, grind and mix, store in a brown ground-mouth bottle. 4.5 Bromocresol green-methyl red mixed indicator: 3 volumes of 1.00g/L bromocresol green (HG3-1220) ethanol solution and 1 volume of 2.00g/L methyl red (HG3-958) ethanol solution. 4.6 Sodium bicarbonate (GB640).
4.7 Sodium bicarbonate solution (GB640): about 25.3g/L solution. Approved by the Ministry of Chemical Industry of the People's Republic of China on June 27, 1991 and implemented on January 1, 1992
HG/T2024-91
Preparation: Weigh 25.3g sodium bicarbonate (4.6) in a 100mL beaker, dissolve in water, transfer quantitatively to a 1000mL volumetric flask, dilute to the mark with water, and shake.
Calibration: Transfer 5.00mL of sodium bicarbonate solution to a 250mL conical flask, add about 50mL of water and 4 drops of bromocresol green-methyl red mixed indicator (4.5), and titrate with hydrochloric acid standard titration solution (4.3) until the solution changes from light blue to light purple, which is the end point. Record the volume Y of the hydrochloric acid standard titration solution (4.3) consumed. 4.8 Anhydrous calcium chloride.
4.9 Calcium chloride solution: about 16.7g/L solution. Preparation: weigh 16.7g of anhydrous calcium chloride (4.8) in a 100mL beaker, dissolve it in water, transfer it quantitatively to a 1000mL volumetric flask, dilute it to the mark with water, and shake it well.
Calibration: transfer 2.00mL of calcium chloride solution to a 250mL conical flask, add about 80mL of water, 5mL of potassium hydroxide solution (4.1), and about 30mB of calcein-phenol mixed indicator (4.4). Under a black background, use a burette (5.2) to transfer the EDTA standard titration solution (4.2) and titrate until the yellow-green fluorescence of the solution suddenly disappears and red appears, which is the end point. Record the volume V of the consumed EDTA standard titration solution (4.2).
5 Instruments and equipment
5.1 Experimental device (see Figure 1):
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Figure 1 Experimental device
One-drum gas loading.? -Gas rotor flowmeter.-Temperature controller.4. Constant temperature water bath + 5 electric heaters, 6 temperature probes! Glassware
Neck flask temperature
Anti-connector
Bubber head
5.1.1 Gas rotor flowmeter: 16~160L/h; 5.1.2 Temperature controller: 0~100℃,
HG/T2024-91
5.1.3 Constant temperature water bath: temperature controlled at 60±0.2℃, 5.1.4 Glass condenser: internal cooling, ground mouth 29mm /32mm, length 300mm5.1.5 Three-necked flask, ground mouth 29mm/32mm, 500mL, 5.1.6 Thermometer: 50~100℃, scale 0.1℃, 5.1.7 Bubble head: sand core, spherical (diameter 25mm) or cylindrical (diameter 20mm, length 24mm), 5.2 Burette (acid type): 50mL,
5.3 Burette (acid type): 10mL.
6 Water treatment agent sample
6.1 Water treatment agent sample solution: 1.00mL contains 0.500mg water treatment agent (on a dry basis), and can also be prepared into other concentrations as needed.
Preparation: Weigh α grams of water treatment agent sample using the reduction method, accurate to 0.0002g, in a 500mL volumetric flask; add water to dissolve, dilute with water to the scale, and shake well.
The value is calculated according to formula (1)
0.500X500
Where: X is the percentage of solid content in the sample, %. 7 Determination steps
7.1 Preparation of test solution
(1)
Use a burette (5.2) to add sodium bicarbonate solution (4.7) azmL to a 500mL volumetric flask. Transfer 5.00mL of water treatment agent sample solution (6.1), add 250mL of water, and shake well. Use a burette (5.2) to slowly add calcium chloride solution (4.9) asml, dilute to the scale with water, and shake well to prepare a test solution containing 5.00mg of water treatment agent, 240mg (6.00mmol) of calcium ions (Ca2+) and 732mg (12.0mmol) of bicarbonate ions (HCO-) in 1L.
the values of a2 and αs can be calculated according to formula (2) and formula (3) respectively: a2
wherein: V.-
0.0120×500
V+C1/5.00
the volume of standard hydrochloric acid solution consumed when standardizing sodium bicarbonate solution, mL; -the concentration of standard hydrochloric acid solution when standardizing sodium bicarbonate solution, mol/L; 0.0120——the concentration of bicarbonate in the test solution, mol/L, 5.00the volume of sodium bicarbonate solution (4.7) transferred during calibration, mL. as
0.00600×500
Vz*c/2.00
The volume of EDTA standard titration solution consumed when calibrating calcium oxide solution, mL Wherein. V2
The concentration of EDTA standard titration solution when calibrating calcium chloride solution, mol/L; 0.00600--The concentration of calcium ions in the test solution, mol/L; 2.00--The volume of calcium chloride solution (4.9) pipetted during calibration, mL. 7.2 Determination of scale inhibition performance
\ (2)
(3)
Put about 450mL of test solution (7.1) in a 500mL three-necked flask. Pour the flask into a constant temperature water bath at 60±0.2℃ and install it according to (5.1). At the same time, blow air in at a flow rate of 80L/h. After 6 hours, stop blowing air, take out the three-necked flask, and let it cool to room temperature. This solution is the calcium ion stable concentration solution. Transfer 25.00mL of this solution to a 250mL conical flask, add about 80mL of water, and use a 10mL burette (5.3) In addition, the stable concentration of calcium ions is determined by the method of calibrating calcium nitride solution. The volume V of the consumed EDTA standard titration solution (42) is recorded.
8 Expression of the measurement results
HG/T2024-91
The scale inhibition performance of water treatment agents is expressed as the stable concentration of calcium ions X (mg/L), calculated according to formula (4): X=:2X40.08×1000=1603×V.
Where: V: - the volume of the EDTA standard titration solution consumed when determining the stable concentration of calcium ions, mL; the concentration of the EDTA standard titration solution, mol/L, 25.00 - the volume of the solution with stable concentration of calcium ions, mL40.08 - the mass of the
son.
+（4）
Equivalent to 1.00mL EDTA standard titration solution [c（EDTA）)=1.000moi/L), the result of calcium ion expressed in milligrams should be expressed to two decimal places.
9Tolerance difference
Take the arithmetic mean of the two determination results as the measurement result. Case Acrylic acid and its sodium salt, the absolute difference between the two determination results: the stable calcium ion concentration is within the range of 25-50mg/L, not more than 1.5mg/L, and the difference between the determination results of different laboratories is not more than 3.4mg/L. Additional remarks:
This standard was proposed by the Science and Technology Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Tianjin Chemical Industry Research Institute of the Ministry of Chemical Industry. This standard was drafted by Nanjing Institute of Chemical Technology. The main drafters of this standard are Zhou Bensheng, Yang Jinxiang, Lu Jianying, and Feng Zhiying. People's Republic of China
Measurement method for scale inhibition performance of water treatment agents
HG/T2024-91
Editorial Department of Chemical Industry Standards
(Institute of Standardization, Ministry of Chemical Industry)
Postal Code: 100013
Copyright reserved. No reproduction allowed
Format 880×12301/16 Printing Sheet 1/2
Word Count 7800
First Edition in September 1991
Reverse, First Printing in September 1991
Print Quantity 1-500
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