GB/T 4372.1-2014Methods for chemical analysis of zincoxide produced by direct process - Part 1: Determination of zinc oxide content - Na2EDTA titration method (English PDF)

3.1

ascorbic acid.

3.2

Reference zinc oxide (wZnO>=99.999%). before use at 800 °C burning 2h ~ 3h, removed, placed in a desiccator to cool to room temperature.

3.3

sulfate (rho1.84g/mL).

3.4

ammonia.

3.5

sulfate (13).

3.6

Aqueous ammonia (11).

3.7

hexamethylenetetramine - sulfuric acid buffer solution (pH value 5-6). Weigh 300g hexamine in 2000mL beaker

950mL dissolved in water (if there is a red solution with a cotton filter), then add 50mL sulfuric acid (11), and mix.

3.8 sodium sulfite solution

Weigh 30g of anhydrous sodium sulfite dissolved in 200mL of water was added 50mL sulfurous acid, pH 6 left control

Right (effective today).

3.9 potassium iodide solution (200g/L)

Weigh 20g of potassium iodide was dissolved in 100mL of water, add a little faded to yellow ascorbic acid (when used

Preparation).

3.10

methyl red solution (1.0g/L).

3.11

XO solution (2g/L).

3.12 disodium ethylenediaminetetraacetate (by Na2EDTA) standard solution (c~0.06mol/L)

Preparation. Weigh 22.87gNa2EDTA, add water, heat gently to dissolve, cooled to room temperature and transferred to 1000mL volumetric flask, dilute to the mark with water

Degree and mix thoroughly. Calibration after placing 3d.

Calibration. Accurately weigh in at 800 °C take 0.50000g (accurate to 0.00002g) benchmark zinc (3.2) 3 parts (front oxide in porcelain dish

Burning 2h ~ 3h) in 300mL beaker, calibrated by analyzing step 6.3. Averaged, the difference does not meet the requirements should be re-calibrated.

Along with the calibration for the blank test.

According to formula (1) calculating Na2EDTA standard solution (3.12) of the actual concentration.

c = (V-V0) × 0.08137 (1) […]