Rapid determination of ash content in the hottest

Rapid determination of ash content of calcium carbonate filling paper

key words: calcium carbonate filler; Ash; Rapid determination

with the development of alkaline (neutral) papermaking, calcium carbonate is widely used as a cheap, high-quality and easily available papermaking filler. For example, the production cost has decreased significantly. He Jianjie, accurately measuring the ash content of calcium carbonate in paper products (as the basis for adjusting the dosage of calcium carbonate), is the method this paper attempts to elaborate

1 method principle

based on the principle that calcium carbonate can completely react with hydrochloric acid, the content of calcium carbonate can be calculated by reacting excess hydrochloric acid solution with calcium carbonate and dripping the remaining hydrochloric acid with sodium hydroxide solution

2 determination operation process

accurately weigh about 2g (± 0.0002g) of paper samples with length and width of about 1cm into a 250ml conical flask (another part is weighed for moisture test), add 50ml of distilled water, shake well and wet the paper sample, and accurately add 20ml of 0.5000mol/l hydrochloric acid (the amount of hydrochloric acid can be increased or decreased depending on the ash content); Plug the conical bottle mouth with a rubber plug with a straight glass condensing tube (1m long and 10mm in diameter), and carefully heat and boil the sample on the electric stove for 1min; Stop heating, cool the outer wall of the conical flask with tap water, remove the straight glass condensing tube, wash the inner wall of the condensing tube with a little distilled water (at least twice), and incorporate the washing solution into the conical flask of the sample to be tested; Add 3 drops of 1% phenolphthalein indicator, titrate with 0.5000mol/l sodium hydroxide standard solution until the solution turns pink, and the reaction equivalent point is that it does not fade for 30s, and record the consumed volume V1

while determining the sample, conduct the blank test according to the same conditions and operation steps as the test sample, and the volume of sodium hydroxide standard solution consumed is v0

3 calculate

the CaCO3 ash content of the paper sample is calculated by the following formula:

caco3%= [C (v0-v1) × zero point zero five zero × 100]/[g (1-A)]

c - molar concentration of sodium hydroxide solution for titration, mhv-50a Vickers hardness tester testing diamond ol/L

v1 - volume of sodium hydroxide standard solution consumed by the dripping sample, ML

v0 - volume of sodium hydroxide standard solution consumed by the blank test, ML

a - sample moisture,%

0.050 - mass of 0.5caco3 unit in millimoles 2, polysulfone PSF or PSUR, G

g - the weighed mass of the sample (including water), g

4 notes

4.1 hydrochloric acid is not used for the test sample, mainly because the solubility of calcium sulfate, the reaction product of sulfuric acid and calcium carbonate, is small, which is not suitable for the dissolution reaction of calcium carbonate

4.2 the purpose of using straight glass condensing tubes when testing samples is to enable the acid to fully react with the sample and discharge carbon dioxide when heating the samples, and to quickly cool the HCl escaping with water vapor (at this concentration, the boiling point of hydrochloric acid is basically close to pure water). Attention should be paid to strengthening the construction of product safety department. After washing, the washing solution should be incorporated into the solution to be tested