Pulp acid-insoluble ash refers to the content of inorganic substances in pulp that are insoluble in acid medium except fibers. The commonly used determination method is the acid insoluble matter determination method, and its main steps are as follows:
Sample preparation: Weigh a certain amount of pulp sample and record its weight, and put it into a beaker or ash dish.
Digestion: Add nitric acid and hydrofluoric acid (or hydrochloric acid) for digestion. The digestion temperature is usually between 120°C-130°C and the duration is 1-2 hours.
Precipitation: Precipitate the digested liquid, and usually use centrifugation or filtration to separate the precipitate.
Cleaning: Wash the precipitate, usually alternately with distilled water and ethanol several times.
Drying: Dry the washed precipitate to constant weight. The drying temperature and time are usually the same as the ash method.
Programmed heating: heat the dried precipitate to 550°C-600°C and bake for 2-3 hours to burn the organic matter and leave only the inorganic matter, namely the acid-insoluble ash.
Cooling and weighing: Take out the sample, place it in a Drying Oven to cool naturally, then re-weigh the sample and the beaker or ash dish to obtain the weight of the acid-insoluble ash in the sample.
Calculation: The formula for calculating the acid-insoluble ash content is: acid-insoluble ash content (%)=(sample acid-insoluble ash weight/sample weight)×100%.
NBCHAO reminds you: In order to avoid errors when measuring acid-insoluble ash, attention should be paid to the cleaning of digestion liquid and sediment, the accuracy of weighing, the control of heating temperature and time, and the time of drying and cooling.
NBCHAO reminds you: In order to avoid errors when measuring acid insoluble ash, it is necessary to pay attention to details such as cleaning of the digestion liquid and sediment, accuracy of weighing, control of heating temperature and time, and drying and cooling time.
