INVESTIGATION OF BOUND DIFFUSION OF ULTRAFINE PARTICLES OF FE-III HYDROXIDE IN A POLYMERIC SORBENT BY MOSSBAUER-SPECTROSCOPY

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.