GB/T 19282-2014Analytic method for Lithium hexafluorophosphate (English PDF)

3.1 General provisions

The reagents and water, which are used in this standard, refer to the first-grade pure reagents and the first-grade water, which are specified in GB/T 6682-2008, unless other requirements are specified. For the standard solutions for chemical analysis, standard solutions of impurities, preparations and products, which are used in the test, they shall be prepared in accordance with the provisions of HG/T 3696.1, HG/T 3696.2, HG/T 3696.3, unless other requirements are specified.

3.2 Identification test

3.3 Determination of cation content

3.3.1 Standard addition method

3.3.1.1 Method summary

The content of each cation in the specimen is determined, by standard addition method, on an inductively coupled plasma optical emission spectrometer (ICP-OES), which has a hydrofluoric acid-resistant sampling system.

3.3.1.2 Reagents

3.3.1.3 Instruments and equipment

3.3.1.4 Analytical procedures

3.3.1.4.1 Preparation of test solutions

3.3.1.5 Result calculation

The cation content is calculated in mass fraction w1; the value is expressed in mg/kg; it is calculated according to formula (1).

3.3.2 Working curve method

3.3.2.1 Method summary

The content of each cation in the specimen is determined, by the working curve method, on an inductively coupled plasma optical emission spectrometer (ICP-OES), which has a hydrofluoric acid-resistant sampling system.

3.3.2.2 Reagents

It complies with the requirements, which are given in 3.3.1.2.

3.3.2.3 Instruments and equipment

It complies with the requirements, which are given in 3.3.1.3.

3.3.2.4 Analytical procedures

3.3.2.5 Result calculation

The cation content is calculated in mass fraction w1; the value is expressed in mg/kg; it is calculated according to formula (2).

3.4 Determination of anion content

3.4.1 Method summary

The chloride ion and sulfate ion, in lithium hexafluorophosphate, are separated by chromatographic column; detected by conductivity detector. The content of detected anion is calculated by external standard method.

3.4.2 Reagents

3.4.2.1 Water. Deionized water, which has a conductivity (25 °C) not greater than 0.0055 mS/m.

3.4.2.2 Ice water. Add an appropriate amount of ice cubes to the water. Use it, when the water temperature is <= 4 °C.

3.4.2.3 Regeneration fluid. According to the suppressor used and its usage, refer to the instruction manual of the suppressor, to select a suitable regeneration fluid.

3.4.3 Instruments and equipment

3.4.3.1 Ion chromatograph. An analytical system, which is resistant to fluoride corrosion.

3.4.3.1.1 Chromatographic column. The resolution of the detected anion R >= 1.5.

3.4.3.1.2 Filter membrane. <= 0.45 µm.

3.4.3.1.3 Detector. Conductivity detector, or other detectors, if it can be confirmed that it has the same function.

3.4.3.2 Volumetric flask. Polyethylene or other corrosion-resistant materials, which have a volume of 100 mL.

3.4.4 Analytical procedures

3.4.4.1 Preparation of working curve solution

Use a suitable pipette, to pipette each standard use solution into four 100 mL volumetric flasks, according to the provisions of Table 2. Use water to dilute it to the mark. Shake well.

3.4.5 Result calculation

The mass fraction of anion content is calculated in w2; the value is expressed in mg/kg; it is calculated according to formula (3).

3.5 Determination of chloride ion content

3.5.1 Reagents

3.5.1.1 Nitric acid solution. 1 + 2.

3.5.1.2 Silver nitrate solution. 17 g/L.

3.5.1.3 Chloride standard solution. 1 mL solution contains 1 µg of chloride (Cl). Pipette 10 mL of chloride standard solution, which is prepared according to HG/T 3696.2. Put it in a 100 mL volumetric flask. Use water to dilute it to the mark. Shake well. Pipette 1 mL into a 100 mL volumetric flask. Use water to dilute it to the mark. Shake well. Store it at 4 °C. The validity period is 30 days.

3.5.2 Analytical procedures

3.6 Determination of sulfate content

3.6.1 Method principle

In hydrochloric acid medium, barium ions and sulfate ions form insoluble barium sulfate. When the content of sulfate ions is low, barium sulfate will be in suspension, within a certain period of time, making the solution turbid, which can be determined, by the visual turbidimetry.

3.6.2 Reagents

3.6.2.1 Absolute ethanol.

3.6.2.2 Hydrochloric acid solution. 1 + 1.

3.6.2.3 Barium chloride solution. 250 g/L.

3.6.2.4 Sulfate standard solution. 1 mL solution contains 1.0 µg of sulfate (SO4). Pipette 10 mL of sulfate standard solution, which is prepared according to HG/T 3696.2. Put it in a 100 mL volumetric flask. Use water to dilute it to the mark. Shake well. Pipette 1 mL into a 100 mL volumetric flask. Use water to dilute it to the mark. Shake well. Store it at 4 °C. The validity period is 30 days.

3.6.3 Analytical procedures

3.6.3.1 Preparation of standard turbidity solution

Pipette 0.00 mL, 5.00 mL, 10.00 mL, 15.00 mL of sulfate standard solution, into a 25 mL colorimetric tube, respectively. Add 0.3 mL of hydrochloric acid solution and 3 mL of absolute ethanol in sequence. Then use water to dilute it to 25 mL. Shake well. Add 2 mL of chlorine barium chloride solution. Shake well.

3.6.3.2 Determination

Weigh about 5 g of the specimen in the glove box, accurate to 0.01 g. Take it out and place it in a polyethylene beaker, which is filled with 15 mL of water. Dissolve and filter it into a 25 mL colorimetric tube. Then treat it, together with the standard turbidity solution at the same time. The turbidity of the solution is compared with that of the standard turbidity solution.

3.7 Determination of moisture

3.7.1 Method principle

Same as Chapter 3 of GB/T 6283-2008.

3.7.2 Instruments and equipment

3.7.2.1 Automatic moisture analyzer. Coulomb coulometric method.

3.7.2.2 Glove box. dew point < -40 °C.

3.7.3 Analytical procedures

The analytical procedure shall be carried out in a glove box. Weigh about 0.5 g of the specimen, accurate to 0.001 g. Put the specimen into the measuring bottle of the automatic moisture analyzer, until it is completely dissolved. Stir evenly. Then measure its moisture.

3.7.4 Result calculation

The mass fraction w3 of water, expressed in mg/kg, is calculated according to formula (4).

3.8 Determination of dimethyl carbonate (DMC) insoluble content

3.8.1 Method summary

Use dimethyl carbonate to dissolve the specimen. Use a membrane filtration device to filter it. Dry it at 105 °C ± 2 °C, until the mass is constant.

3.8.2 Reagents

Dimethyl carbonate (DMC). Moisture < 0.0010%.

3.8.3 Instruments and equipment

3.8.3.1 Membrane filtration device. 1000 mL, which is matched with a filter membrane with a diameter of 50 mm.

3.8.3.2 Filter membrane. The material is polytetrafluoroethylene or other hydrofluoric acid-resistant filter membrane, which has a pore size of 0.45 µm and a diameter of 50 mm.

3.8.3.3 Vacuum pump and filter equipment.

3.8.3.4 Magnetic stirrer.

3.8.3.5 Beaker. It has lid AND is made of polyethylene or other corrosion-resistant material.

3.8.3.6 Electric heating constant temperature drying box. An explosion-proof constant temperature box, whose temperature can be controlled at 105 °C ± 2 °C.

3.8.5 Result calculation

The insoluble content of dimethyl carbonate (DMC) is calculated in mass fraction w4; the value is expressed in mg/kg; it is calculated according to formula (5).

3.9 Determination of free acid content

3.9.1 Method summary

Use a micro-burette. Use bromothymol blue as an indicator. Use standard titration solution of sodium hydroxide, to titrate the free acid in the specimen.

3.9.2 Reagents

3.9.2.1 Sodium hydroxide standard titration solution. c(NaOH) ~ 0.01 mol/L

Preparation. Pipette 100 mL of sodium hydroxide standard solution, which is prepared according to HG/T 3696.1. Place it in a 1000 mL volumetric flask. Use carbon dioxide-free water to dilute it to the mark. Shake well.

3.9.2.2 Ice water. Add an appropriate amount of ice cubes to the water. Use it when the water temperature is <= 4 °C.

3.9.2.3 Bromothymol blue indicator solution. 1 g/L.

3.9.3 Instruments and equipment

3.9.4 Analytical procedures

Weigh about 10 g of the sample by weight loss method, accurate to 0.0002 g. Quickly pour the sample into a beaker, which contains 100 mL of ice water. Shake the beaker, to dissolve the specimen quickly. Add 10 drops of bromothymol blue indicator solution.

Use sodium hydroxide standard titration solution, to rapidly titrate it to light blue (no color fading in 10 s), which is the end point. At the end point, the temperature of the solution shall still remain <= 4 °C.

3.9.5 Result calculation

The free acid content is calculated in terms of the mass fraction w5 of hydrofluoric acid (HF); the value is expressed in mg/kg; it is calculated according to formula (6). […]