GB 28655-2012[GB/T 28655-2012] Ammonium bifluoride for industrial use (English PDF)

4.1 Appearance. white crystal.

4.2 ammonium hydrogen industry should meet the requirements of Table 1.

Table 1

project

index

Premium grade First grade Qualified

Ammonium bifluoride (of NH4HF2) (dry basis) w /% >= 98.0 97.0 96.0

Ammonium fluorosilicate [(NH4) 2SiF6] w /% <= 0.5 1.5 3.0

Loss on drying w /% <= 1.5 3.0 4.0

Residue on ignition w /% <= 0.1 0.2 -

Sulfate (in terms of SO4) w /% <= 0.1 0.1 -

5.1 Safety Tips

Ammonium bifluoride in this test method the sample taken toxic, deliquescent in the air and the solution is strongly acidic, during operation

Try not to be in direct contact with the skin. Reagents used is corrosive, the operator should be careful to avoid contact with the skin, such as

Contact with the skin immediately wash with water, severe cases should seek medical care immediately.

5.2 General Provisions

This standard reagents and water, in the absence of other requirements specified, refer to three predetermined analytical reagents and GB/T 6682-2008 of

Water, used in the test standard titration solution, impurity standard solution, formulations and products, in the absence of other requirements specified, are by HG/T 3696.1,

HG/T 3696.2, preparing a predetermined HG/T 3696.3 is.

5.3 Visual inspection

Determined by visual appearance in natural light.

5.4 Determination of the content of ammonium bifluoride

5.4.1 Method summary

Under the temperature of 0 degrees C, was added a saturated solution of potassium nitrate, in a sample to eliminate the interference of ammonium fluorosilicate, bromine thymol blue - neutral red is

Indicator, titrated titrated with standard sodium hydroxide solution.

5.4.2 Reagents and materials

5.4.2.1 saturated potassium nitrate solution.

5.4.2.2 sodium hydroxide standard titration solution. c (NaOH) ~0.5mol/L.

5.4.2.3 Bromothymol Blue - neutral red mixed indicator solution.

Weigh 0.1g 0.1g of bromothymol blue and neutral red, was dissolved in ethanol 200mL95%.

5.4.2.4 ice. prepared with distilled or deionized water.

5.4.3 Analysis of step

Weigh about 0.8g sample by 5.6 after drying, the nearest 0.0002g, with a small amount of cold water to transfer the sample to a pre-filled with 20mL

Polyethylene beaker, 50g of potassium nitrate and a saturated solution of crushed ice, and stirred to dissolve the sample. Add 5 drops of bromothymol blue - mixing neutral red

Indicator solution, dark green end point titration with standard sodium hydroxide solution to titrate. After the titration solution is mixed with ice water to maintain a state immediately used

Determination of the content of ammonium fluoride.

5.4.4 calculation results

Ammonium fluoride ammonium hydrogen fluoride content (of NH4HF2) w1 mass fraction basis, calculated according to formula (1).

w1 =

(V/1000) cM

m x 100%

(1)

Where.

Sodium hydroxide standard titration solution volume V --- titration test solution consumed value in milliliters (mL);

Accurate value of the concentration of the solution of sodium hydroxide standard titration --- C, in units of moles per liter (mol/L);

Value m --- mass of the sample in grams (G);

--- numerical molar mass M ammonium bifluoride (NH4HF2), in units of grams per mole (g/mol) (M = 57.04).

Parallel to the arithmetic average of the measurement results of the measurement result, the absolute difference determination results parallel to not more than 0.3%.

5.5 Determination of the content of ammonium fluorosilicate

5.5.1 Method summary

After determination of the content of ammonium fluoride was subjected to suction filtration in the cold state. At 80 degrees C, fluorine potassium silicate precipitate was dissolved, to

Phenolphthalein as an indicator, titration is titrated with standard sodium hydroxide solution.

5.5.2 Reagents

5.5.2.1 chloride ethanol solution.

Weigh about 2g of potassium chloride dissolved 100mL50% ethanol.

5.5.2.2 sodium hydroxide standard titration solution. c (NaOH) ~0.1mol/L.

5.5.2.3 phenolphthalein indicator solution. 10g/L.

5.5.3 instruments and equipment

5.5.3.1 polyethylene funnel.

5.5.3.2 polyethylene beaker.

5.5.3.3 constant temperature water bath. capable of controlling a temperature of 80 degrees C ~ 85 degrees C.

5.5.4 Analysis of step

5.4.3 Determination solution was filtered through a polyethylene funnel and slow quantitative filter paper, held by suction filtration at 0 degrees C close state. With pre

KCl was washed thoroughly with ethanol cooled to precipitate, the precipitate together with the original filter into a beaker together. Adding about 100mL temperature

Of water, heated on a water bath to 80 degrees C, add 5 drops of phenolphthalein indicator solution, titrated with standard sodium hydroxide solution was titrated to light red solution.

5.5.5 calculation results

Content fluorosilicate, ammonium fluorosilicate, ammonium [(NH4) 2SiF6] w2 mass fraction basis, according to equation (2).

w2 =

(V/1000) cM

m x 100%

(2)

Where.

Sodium hydroxide standard titration solution volume V --- titration test solution consumed value in milliliters (mL);

Accurate value of the concentration of the solution of sodium hydroxide standard titration --- C, in units of moles per liter (mol/L);

Value m --- mass of the sample in grams (G);

--- M ammonium fluorosilicate [14

Numerical 2SiF6] molar mass (NH4), in units of grams per mole (g/mol) (M = 44.54).

Parallel to the arithmetic average of the measurement results of the measurement result, the absolute difference determination results parallel to no greater than 0.1%.

5.6 Determination of loss on drying

5.6.1 Method summary

The sample was dried in a silica gel desiccator, loss on drying is determined according to the reduction of the sample before and after drying.

5.6.2 instruments and equipment

5.6.2.1 platinum (or polytetrafluoroethylene) crucible.

5.6.2.2 Silicone dryer. indicator using silica gel desiccant.

5.6.3 Analysis of step

Weigh about 1g sample, accurate to 0.0002g, was placed on a silica gel dryer to a constant mass in a covered platinum (or PTFE

Ethylene) crucible, placed in a silica gel desiccator, and dried to open the lid of the crucible, placed immediately weighed 8h, fluorinated sample after drying

Determination of ammonium hydrogen content.

5.6.4 calculation results

Loss on drying w3 mass fraction basis, calculated according to formula (3).

w3 = m1-m2m x 100%

(3)

Where.

Numerical sample before drying and M1 --- crucible crucible mass in grams (G);

--- M2 dried sample values and quality of the crucible crucible in grams (G);

Value m --- mass of the sample in grams (g).

Parallel to the arithmetic average of the measurement results of the measurement result, the absolute difference determination results parallel to not more than 0.2%.

Determination of ignition residue content of 5.7

5.7.1 Method summary

The sample was fired in a high temperature furnace to constant mass, determined according to the ignition residue content reduction before and after burning.

5.7.2 instruments and equipment

5.7.2.1 platinum dish.

5.7.2.2 temperature furnace. temperature control can 700 degrees C +/- 25 degrees C.

5.7.3 Analysis of step

Weigh about 5g sample, accurate to 0.0002g, was placed at 700 degrees C +/- 25 degrees C to constant mass burning platinum dish in ventilated

Good ventilation hood, slowly heated to complete the volatiles were evaporated. The platinum dish was placed 700 degrees C +/- 25 degrees C high temperature burning furnace to constant mass.

5.7.4 calculation results

Residue on ignition w4 mass fraction basis, calculated according to formula (4).

w4 = m1-m2m x 100%

(4)

Where.

The residue on ignition values after M1 --- quality and platinum dish in grams (G);

Numerical empty platinum dish mass m2 ---, in grams (G);

Value m --- mass of the sample in grams (g).

Parallel to the arithmetic average of the measurement results of the measurement result, the absolute difference determination results parallel to 0.02%.

5.8 Determination of the sulfate content

5.8.1 Method summary

Hydrochloric acid and sodium carbonate solution was added a small amount in a sample, again evaporated to dryness on a water bath. After the residue was dissolved barium chloride solution of sulfuric acid

Salt precipitation as barium sulfate, turbidity standard for comparison.

5.8.2 Reagents

5.8.2.1 95% ethanol.

5.8.2.2 hydrochloric acid solution. 21.

5.8.2.3 sodium carbonate solution. 100g/L.

5.8.2.4 barium chloride solution. 100g/L.

5.8.2.5 sulfate standard solution. 1mL solution containing sulfate (SO4) 0.1mg.

Pipette with a pipette 10mL sulfate standard solution according to GB/T 3696.2 formulated, a 100mL volumetric flask, dilute with water

To the mark.

5.8.3 Analysis of step

0.50g +/- 0.01g sample is weighed, placed in a platinum dish, the following operations carried out in a well ventilated hood was added 0.5mL carbonate

Sodium, 10 mL hydrochloric acid solution, evaporated to dryness on a water bath. After the operation was repeated three more times, with about 1mL 20mL aqueous hydrochloric acid solution

The residue was dissolved, the solution was transferred to a 100mL volumetric flask, diluted with water to the mark.

Pipette with a pipette 20mL of the solution (filtered if necessary), a 50mL colorimetric tube, add water to 25mL, was added 3mL

95% ethanol and 2mL barium chloride solution, allowed to stand 1h turbidimetry, turbidity should not be deeper than the standard turbidimetric solution.

Turbidity standard solution was prepared ratio. 0.3mL was added a sodium carbonate solution, 6 mL solution of hydrochloric acid in a porcelain evaporating dish, evaporated on a water bath to

dry. The residue was dissolved with a small amount of water and 0.2mL of hydrochloric acid solution, and the solution was transferred to a 50mL colorimetric tube, labeled sulfate was added 1.00mL

Standard solution, from the "25 mL water was added to the" start, and treated in the same sample simultaneously.

8.2 net weight 25kg, or according to user requirements negotiated net content.

8.3 Industrial ammonium hydrogen fluoride package, the inner four artificial Zhakou with Vinyl rope or other comparable quality rope, or its equivalent with other parties

Sealing; packaging sewn securely, and not leaky jumper phenomenon.

8.4 during the transportation industry ammonium bifluoride should be covered, the temperature should not exceed 50 degrees C, to prevent the sun, rain, moisture; not with acid, alkali

Mixed transportation.

8.5 Industrial ammonium bifluoride should be stored in a cool warehouse dedicated hazardous chemicals, the temperature should not exceed 50 degrees C, to prevent the sun, rain and damp;

Not with acid, alkali mixed storage.