The specific surface test method is divided into adsorption method, air permeability method and other methods according to different test ideas. The air permeability method is to fill the powder to be tested in the air pipe to a certain bulk density and determine the size of the powder specific surface area analyzer according to the air permeability. Smaller surface test range and lower accuracy;
Adjust the mercury level to the lowest scale of the gas measuring tube. After passing high purity nitrogen, close S3 and measure the gas pressure. Open the S1 gas into the sample tube and contact with the sample. When equilibrium is reached (the pressure does not change more than 0.1 mmHg column within 1 min), record the pressure at this time. Raise the mercury surface to achieve successive heights and measure the corresponding equilibrium pressure
The solid surface has adsorption characteristics, and coal adsorbs gas and liquid. The surface area and porosity play a major role in the adsorption phenomenon, so the strength of the adsorption is closely related to the surface area. The adsorption isotherm is a source of information about the pore structure of the adsorbent, the heat of adsorption, and other physical and chemical characteristics. The adsorption isotherm of the adsorbate can be obtained under the conditions of constant temperature and wide range of relative pressure
Because nitrogen is a chemically inert gas and chemical adsorption is not likely to occur at the temperature of liquid nitrogen, the low temperature nitrogen adsorption method is the most commonly used method for measuring specific surface area.
Generally, it has a relatively large specific surface area analyzer; the performance of adsorbent catalyst carbon black and other materials is closely related to the specific surface area. Certain performance requires a certain range of specific surface requirements; but it is not that the larger the specific surface area, the better the powder quality.
Measure the volume from the sample tube containing the sample to the piston S1 to expand the high-purity nitrogen into the sample tube, record the pressure after the equilibrium is formed, and record the pressure under the corresponding scale on the measuring tube. Calculate the volume of dead space by the following formula
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