Vi. Khromov et al., INVESTIGATION OF BOUND DIFFUSION OF ULTRAFINE PARTICLES OF FE-III HYDROXIDE IN A POLYMERIC SORBENT BY MOSSBAUER-SPECTROSCOPY, Russian chemical bulletin, 45(4), 1996, pp. 841-850
Bound diffusion of ultrafine particles of Fe-III hydroxide in the pore
s of a solvated polymeric sorbent has been discovered and investigated
by Mossbauer spectroscopy. Particles with diameters of 30 Angstrom le
ss than or equal to d less than or equal to 90 Angstrom were precipita
ted from an aqueous solution in the pores of the poly(divinylbenzene-e
thylstyrene) ''Porolas A'' sorbent. The Mossbauer spectra obtained at
T > 250 K (i.e., above the crystallization and glass transition points
of the liquid in the pores, viz., water or glycerol) were found to as
sume the shape of a superposition of broadened and nonbroadened compon
ents, which is characteristic of bound diffusion. Experimental data we
re treated in terms of two alternative models of bound diffusion, viz.
, in harmonic (Brownian overdamped oscillator) and rectangular potenti
als. The following values for the parameters of bound diffusion (diffu
sion coefficient D and diffusion displacement r) at room temperature w
ere found: for glycerol, D = 0.3 . 10(-9); 0.5 . 10(-9) cm(2) s(-1) an
d r = 0.14; 0.38 Angstrom; for water, D > 2 . 10(-8) cm(2) s(-1) and r
= 0.22; 0.45 Angstrom. Unlimited diffusion of particles in the solvat
ed sorbent was not observed. No diffusion of the particles was observe
d in the dry sorbent.