Mercury intrusion curve

To bring the two curves into correspondence it is necessary to choose some reference point on the mercury intrusion curve, not too close to the lower... 

For membranes with pore diameters smaller than 3.5 nm, the nitrogen adsorption/desorption method based on the widely used BET theory ean be employed. This measurement technique, however, is good only for pore diameters ranging from 1.5 nm to 100 nm ( = 0.1 micron). Typical data from this method are split into two portions adsorption and desorption. The nitrogen desorption curve is usually used to describe the pore size distribution and corresponds better to the mercury intrusion curve. Given in Figure... 

The apparent density, that is, the volume of a given mass of sample plus voids divided into the sample mass can be calculated as a function of the void and pore volume from a mercury intrusion curve. The ambient to 60000 psia curve for the silica gel sample is illustrated in Fig. 21.2. Using the volume of mercury intruded at various pressures, the volume of the sample including voids and pores, and thus, the apparent density can be obtained, as shown in Table 21.2. The calculated apparent densities are obtained by subtracting the intruded volume from the initial sample volume and dividing the resulting value into the sample weight. 

Fig. 24. (a) Mercury intrusion curves at = 3, 4, and 6. (b) Pore-size distribution solid... 

The value of the contact angle 6 may vary between the intrusion and extrusion of the mercury, making the interpretation of the hysteresis fairly difHcult. Generally speaking, only the mercury intrusion curve is used to determine the pore distribution. 

Mercury intrusion curves of SDDP fractions and bulk exhibit similar profiles (a typical porogram is shown in figure 4). 

Figure 2. Mercury intrusion curve of a typical high-pore-volume silica used in...

It is evident that the permeability of the heated and rehydrated cements was not simply controlled by the pore volume as determined by mercury porosimetry. Howeveri the shape of some of the mercury intrusion curves in Figures 1-4 indicates that at the maximum attainable pressure mercury did not penetrate into the narrowest pores of the heated or rehydrated samples. Furthermore the extensive intrusion-extrusion hysteresis and the large entrapment of mercury are features generally associated with complex pore networks made up of interconnecting channels and cavities of different dimensions. 

Mercury pycnometry experiments allowed to explain these discrepancies by revealing a strong swelling of the CSOs especially in nitrogen. The phenomenon was first strictly established for both ores by comparing the mercury intrusion curves before and after treatment at 700 C in nitrogen the results are given in table 2. 

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