Molecularly-Limited Fractal Surface Area of Mineral Powders

Minerals

Vilem Madr¹  Petr Jandacka²  Jaromir Pistora²  Jan Valicek³ 

[1] Department of Natural Sciences and Humanities, College of Logistics, Palackeho 1381/25, 75002 Prerov, Czech Republic;IT4Innovations Centre and Nanotechnology Centre, VSB—Technical University of Ostrava, 17. listopadu 15/2172, 70833 Ostrava, Czech Republic;Institute of Physics, Faculty of Mining and Geology, VSB—Technical University of Ostrava, 17. listopadu 15/2172, 70833 Ostrava, Czech Republic;

关键词: specific surface area;    fractal dimension;    adsorption;    mineral powder;    dissolution;   

DOI  :  10.3390/min6020044

来源: DOAJ

【 摘 要 】

The topic of the specific surface area (SSA) of powders is not sufficiently described in the literature in spite of its nontrivial contribution to adsorption and dissolution processes. Fractal geometry provides a way to determine this parameter via relation SSA ~ x(D − 3)s(2 − D), where x (m) is the particle size and s (m) is a scale. Such a relation respects nano-, micro-, or macro-topography on the surface. Within this theory, the fractal dimension 2 ≤ D < 3 and scale parameter s plays a significant role. The parameter D may be determined from BET or dissolution measurements on several samples, changing the powder particle sizes or sizes of adsorbate molecules. If the fractality of the surface is high, the SSA does not depend on the particle size distribution and vice versa. In this paper, the SSA parameter is analyzed from the point of view of adsorption and dissolution processes. In the case of adsorption, a new equation for the SSA, depending on the term (2 − D)∙(s2 − sBET)/sBET, is derived, where sBET and s2 are effective cross-sectional diameters for BET and new adsorbates. Determination of the SSA for the dissolution process appears to be very complicated, since the fractality of the surface may change in the process. Nevertheless, the presented equations have good application potential.

【 授权许可】

Unknown