ISSN:
1573-9171
Schlagwort(e):
bound diffusion
;
ultrafine particles
;
nanoparticles
;
Mössbauer spectroscopy
;
polymeric sorbents
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
Abstract Bound diffusion of ultrafine particles of FeIII hydroxide in the pores of a solvated polymeric sorbent has been discovered and investigated by Mössbauer spectroscopy. Particles with diameters of 30 Å 〈-d 〈- 90 Å were precipitated from an aqueous solution in the pores of the poly(divinylbenzene-ethylstyrene) “Porolas A” sorbent. The Mössbauer spectra obtained atyT 〉 250 K (i.e., above the crystallization and glass transition points of the liquid in the pores,viz., water or glycerol) were found to assume the shape of a superposition of broadened and nonbroadened components, which is characteristic of bound diffusion. Experimental data were treated in terms of two alternative models of bound diffusion,viz., in harmonic (Brownian overdamped oscillator) and rectangular potentials. The following values for the parameters of bound diffusion (diffusion coefficientD and diffusion displacementr) at room temperature were found: for glycerol,D = 0.3 · 10−9; 0.5 · 10−9 cm2 s−1 andr = 0.14; 0.38 Å for water,D 〉 2 × 10−8 cm2 s−1 andr = 0.22; 0.45 Å. Unlimited diffusion of particles in the solvated sorbent was not observed. No diffusion of the particles was observed in the dry sorbent.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01431310
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