Mercury injection porosimetry

Fig. 3.6.5 Comparison of mercury injection porosimetry curve with NMR T2 cumulative distribution [25].

The curvature of the interface depends on the relative magnitudes of the adhesive forces between the liquid and the capillary wall and the internal cohesive forces in the liquid. When the adhesive forces exceed the cohesive forces, 9 lies in the range 0° < 9 < 90° when the cohesive forces exceed the adhesive forces, 90° < 9 < 180°. When 9 > 90°, the cos 9 term is negative, resulting in a convex meniscus towards the vapor phase and the liquid level in the capillary falling below the liquid level in the container (capillary depression). This occurs with liquid mercury in glass where 9 = 140° and also with water in capillary tubes coated internally with paraffin wax. Thus, liquid mercury is used in the evaluation of the porosity of solid adsorbents in the mercury injection porosimetry technique (see Section 8.5). 

The primary pore size distributions of the cases A and B in Table 3.5 are experimentally determined by mercury injection porosimetry (MIP) (Fermeglia and Pricl, 2009) on the instrument of PoreMaster GT 60. The MIP enables the measurements of both the pressure required to force mercury into the pores of CLs and the intruded Hg volume at each pressure. The employed equipment operates from 13 kPa to a pressure of 410 MPa, equivalent to the pores with the diameters, d, ranging from 100 [xm to 0.0036 xm. On the other hand, the 3 V method provides a tool to theoretically calculate the agglomerate volume depending on the probe radius. In analogy to the... 

The physical principle is in fact close to porosimetry experiments based on mercury injection. However, because of evident environmental disadvantages of mercury manipulation, it appeared convenient to find other (solid-liquid) systems. This difficulty was overcome by using hydrophobic solids and water [4]. 

A) Pressure-controlled mercury porosimetry procedure. It consists of recording the injected mercury volume in the sample each time the pressure increases in order to obtain a quasi steady-state of the mercury level as P,+i-Pi >dP>0 where Pj+i, Pi are two successive experimental capillary pressure in the curve of pressure P versus volume V and dP is the pressure threshold being strictly positive. According to this protocol it is possible to calculate several petrophysical parameters of porous medium such as total porosity, distribution of pore-throat size, specific surface area and its distribution. Several authors estimate the permeability from mercury injection capillary pressure data. Thompson applied percolation theory to calculate permeability from mercury-injection data. 

In order to visualize the process of non-wetting fluid injection Wood s metal Porosimetry was used [11-16], Wood s metal Impregnation technique is based on the same principles as Mercury Porosimetry, i.e., an immiscible,... 

Because mercury is nonwetting, mercury porosimetry is used to obtain capillary pressure curves during injection (see section on Immiscible Displacement ). This technique allows estimates of pore-size distribution to be made. 

Porosimeter An instrument for the determination of pore size distribution by measuring the pressure needed to force liquid into a porous medium and applying the Young-Laplace equation. If the surface tension and contact angle appropriate to the injected liquid are known, pore dimensions can be calculated. A common liquid for this purpose is mercury hence, the term mercury porosimetry. 

Besides the methods noted above, study of the microstmcture of the surface using SEM, and techniques for studying the fracture surface using the frozen section method (the method whereby soft green sheet containing plastic is chiUed at low temperature and is cut to achieve a brittle fracture surface) are frequently used. Evaluation using mercury porosimetry where mercury is injected into the sample is an effective technique for comparing... 

Mercury Porosimetry and Capillary Flow Porometry - Pore Size Determination In a mercury porosimetry measurement, pressure is used to force mercury into filling the pores and voids of the material. The method is based on the capillary rise phenomenon which exists when a non-wetting liquid climbs up a narrow capillary. As the pressure is increased, mercury infiltrates the pores to occupy a subset of the total pore space, the extent of which depends on the applied external pressure. The injected volume of mercury as a function of pressure is recorded. The pore size and distribution can be resolved using the Young and Laplace model [43]. The pore sizes that can be determined by mercury porosimetry range from a few nanometers to a few hundreds of microns. The method is invasive in that not all the mercury will be expelled from the pores and pores may collapse as a result of the high pressures. Due to this and environmental concerns about mercury pollution mercury porosimetry method is becoming less popular. 

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