Methods for chemical analysis of lithium carbonate,lithium hydroxide monohydrate and lithium chloride—Part 2:Determination of lithium hydroxide content—Acid-alkali titrimetric method
1 Scope
This part of GB/T 11064 specifies the methods for determining the lithium hydroxide content in the lithium hydroxide monohydrate.
This part is applicable to the determination of the lithium hydroxide content in the lithium hydroxide monohydrate, within a range of over 50.00%.
2 Method summary
A test sample is dissolved in a certain amount of hydrochloric acid standard volumetric solution. With methyl red-bromocresol green as the indicator, the total alkalinity of the test solution continues to be titrated with the hydrochloric acid standard volumetric solution, and the lithium hydroxide content is calculated by the consumed hydrochloric acid standard volumetric solution. The sodium and potassium content in the test sample shall be converted into the lithium hydroxide content and subtracted from the calculated results.
3 Reagents
Unless otherwise specified, analytically-pure reagents and deionized water shall be used for purpose of this part.
3.1 Methyl red-bromocresol green indicator: take 30 mL bromocresol green solution (3.1.1) and 10 mL methyl red solution (3.1.2) and mix them well.
3.1.1 Bromocresol green solution: weigh 0.1 g bromocresol green and dissolve it in 100 mL ethanol (95%) solution.
3.1.2 Methyl red solution: weigh 0.2 g methyl red and dissolve it in 100 mL ethanol (95%) solution.
3.2 Hydrochloric acid standard volumetric solution [c(HCl)=0.25 mol/L].
3.2.1 Preparation: pipette 20.8 mL hydrochloric acid into a 1000 mL volumetric flask, dilute to the scale with water and mix well.
3.2.2 Calibration: weigh three portions of 0.6 g (accurate to 0.0001 g) sodium carbonate which has been ignited in a high temperature furnace at 270°C~300°C for 2 h in advance and cooled to room temperature in a dryer, put them in a 250 mL conical flask respectively, add 50 mL water to dissolve them, add 10 drops of methyl red-bromocresol green indicator (3.1), titrate with hydrochloric acid standard volumetric solution (3.2) until the solution turns from green to wine red, boil for 2 min to remove carbon dioxide, cool it, and continue the titration until the solution turns wine red again. The extreme difference of the volumes of hydrochloric acid standard volumetric solution (3.2) consumed for parallel calibration shall not exceed 0.10 mL, and the mean shall be taken. Carry out blank test along with the calibration.
The actual concentration of the hydrochloric acid standard volumetric solution (3.2) is calculated using Equation (1):
Foreword i
1 Scope
2 Method summary
3 Reagents
4 Test sample
5 Analysis procedures
6 Calculation of analysis results
7 Precision
8 Test report
