Anomalous diffusion and the adsorption-desorption process in anisotropic mediaE. K. Lenzi1, L. R. Evangelista1, G. Barbero2 and F. Mantegazza3
1 Departamento de Física, Universidade Estadual de Maringá - Avenida Colombo, 5790, 87020-900 Maringá, Paraná, Brazil
2 Dipartimento di Fisica del Politecnico di Torino - Corso Duca degli Abruzzi 24, 10129 Torino, Italy, EU
3 DIMESAB, Università di Milano-Bicocca - 20052 Monza (MI), Italy, EU
received 18 November 2008; accepted in final form 22 December 2008; published January 2009
published online 30 January 2009
The diffusive process of dispersed particles in a semi-infinite cell of an anisotropic fluid limited by an adsorbing surface is theoretically investigated. The densities of bulk and surface particles are analytically determined, taking into account the conservation of the number of particles immersed in the sample. It is shown that an anomalous diffusion process can take place according to the time scale considered. For short time interval there is a sub-diffusion process, followed by a super-diffusive regime. For large time interval the diffusive process tends to a normal behavior. The analysis is suitable for the description of the adsorption phenomena of neutral as well as charged particles in anisotropic media.
82.20.Db - Transition state theory and statistical theories of rate constants.
66.10.C- - Diffusion and thermal diffusion.
05.60.-k - Transport processes.
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