GB/T 4698.12-2017Methods for chemical analysis of titanium sponge, titanium and titanium alloys - Part 12: Determination of vanadium content - Ammonium ferrous sulfate titration and inductively coupled plasma atomic emission spectrometry (English PDF)

2.1 Method summary

The sample is dissolved in sulfuric acid. Vanadium is oxidized with potassium permanganate in a sulfuric acid medium, and in the presence of urea, sodium nitrite is added to reduce excessively high

Potassium manganate, N-phenyl anthranilic acid as an indicator, ammonium ferrous sulfate standard titration titration of vanadium.

2.2 Reagents

Unless otherwise stated, only reagents identified as analytical grade and laboratory grade II water were used in the analysis.

2.2.1

Nitric acid (rho = 1.42g/L).

2.2.2

Sulfuric acid (1 1).

2.2.3

potassium permanganate solution (5g/L).

2.2.4

urea solution (100g/L).

2.2.5

sodium nitrite solution (10g/L).

2.2.6

Vanadium standard storage solution Weigh 1.785g of vanadium pentoxide (>=99.95%) previously dried at 105 °C placed in 250mL burn

Cup, add 50mL sodium hydroxide solution (10g/L), dissolved by heating, acidified with sulfuric acid (2.2.2) and then an excess of 10mL, transferred to 1000mL volume

Bottle, diluted with water to the mark, mix well. 1 mL of this solution contains 1 mg vanadium.

2.2.7

ammonium ferrous sulfate standard titration solution [c (Fe2) ~0.01mol/L].

2.2.7.1

Preparation Weigh ferric ammonium sulfate 4.0g [Fe (SO4) · (NH4) 2SO4 · 6H2O] 500mL beaker, add.200mL

Sulfuric acid (2.2.2) dissolves. Into a 1000mL volumetric flask, diluted with water to the mark, mix well.

2.2.7.2 Calibration

According to Table 1 Pipette three vanadium standard stock solution (2.2.6) were placed in three 300mL Erlenmeyer flask, the following 2.4.4.1 ~

2.4.4.4. Parallel calibration of ammonium ferrous sulfate standard titration solution (2.2.7) the size of the difference should not exceed 0.10mL, take

The average.

Press (1) Calculate the actual concentration of ammonium ferrous sulfate standard titration solution (2.2.7).

c = m1

V1 × 0.05094 (1)

In the formula.

c --- ferrous ammonium sulfate standard titration solution (2.2.7) the actual concentration, expressed in moles per liter (mol/L);

m1 --- vanadium quality, in grams (g);