GB/T 37632-2019Man-made fiber—Test method for titanium dioxide content (English PDF)

8.1 Preparation of titanium standard solution 1mg/mL

8.1.1 Add 166.8mg of titanium dioxide (5.2) equivalent to 100mg of titanium, 5g~7g of ammonium sulfate (5.4), and 10mL of concentrated sulfuric acid (5.3) into 100mL beaker; slowly heat in a ventilated case till fully dissolved. Cool off the solution naturally to the room temperature.

8.1.2 Pre-add about 30mL of water into the 100mL volumetric flask. Carefully pour the solution into the volumetric flask. After cooling off slightly, rinse the inner wall of the beaker twice with water; pour the eluent into the volumetric flask also.

8.1.3 Add water for several times; shake horizontally and evenly. After cooling off to the room temperature, dilute to the scale; shake evenly; pay attention to releasing the air from the flask during shaking evenly.

NOTE: Protective equipment such as chemical protective glasses and acid-proof gloves needs to be worn during the operation.

8.2 Preparation of standard colorimetric solutions

8.2.1 Pipette 0mL (reagent blank solution), 0.2mL, 0.4mL, 0.6mL, 0.8mL, 1.0mL of titanium standard solution by a graduated pipette; inject them into 100mL volumetric flask, respectively.

8.2.2 Add 50mL of water and 20mL of sulfuric acid solution (5.6), respectively to the above volumetric flask. After mixing evenly, separately add 10mL of 3% hydrogen peroxide solution (5.7).

8.2.3 Add water for several times; shake horizontally and evenly. After cooling off to the room temperature, dilute to the scale; shake evenly; pay attention to releasing the air from the flask during shaking evenly.

8.3 Determination of absorbance for standard colorimetric solutions

Within 1h, use a 3cm or other suitable size cuvette, at the wavelength of 410nm; take the reagent blank solution as the reference solution; adjust the absorbance of the instrument into zero; then measure the absorbance of the standard colorimetric solutions.

8.4 Draw working curve

8.4.1 Draw the working curve by taking the mass of the titanium in the standard

9.3 Determination of the absorbance of the test solution

9.3.1 Within 1h; use a 3cm or other suitable cuvette at the wavelength of 410nm; take reagent blank solution as the reference solution; adjust the absorbance of the instrument into zero; then measure the absorbance of the test solution.

9.3.2 The measured absorbance of the test solution shall be between 0.2 and 0.8.

Otherwise, the concentration of the test solution needs to be adjusted. For instance, if the absorbance is too low, the weight of the specimen can be increased appropriately; if the absorbance is too high, the test solution can be diluted to n times appropriately.

9.3.3 According to the measured absorbance of the test solution, check the mass of titanium in the test solution from the working curve.

A.1 Principle

After the man-made fiber is sufficiently carbonized, it is burned at a high temperature; then obtain the white ash without black spots. Repeatedly burning, cooling, drying and weighing the ash till it is constant weight.

A.2 Apparatus and materials

A.2.1 Balance, the minimum scale value of 0.1mg.

A.2.2 Porcelain crucible, 50mL or 100mL

A.2.3 Electric furnace, direct-heating type, anti-fire.

A.2.4 Muffle furnace, temperature range of 650°C~1000°C; the temperature control accuracy of ±10°C

A.2.5 Dryer, desiccant: color-changing silica gel.

A.2.6 Others, crucible tongs […]

A.3 Test procedure

A.3.1 Weighing specimen

Accurately weight the dried specimen, accurate to 0.1mg. Take 500mg of semi-dull fiber; and 100mg of full-dull fiber.

A.3.2 Crucible with constant weight

Place the porcelain crucible into the muffle furnace at the temperature of (750±10) °C and burn for 60min. Use the crucible tongs to move the furnace mouth, cool off to the 200°C or so; then take out.

After cooling off the porcelain crucible for 5min the air, move to the dryer. Cool off for more than 3min; weigh the mass of the crucible, accurate to 0.1mg.

Repeat the procedures of burning (30min each time), cooling, and weighing till the difference of two weights after burning is no greater than 0.5mg. Take the final weighing mass as the constant weight of the crucible. […]