Investigation of bound diffusion of ultrafine particles of FeIII, hydroxide in a polymeric sorbent by Mössbauer spectroscopy

Abstract

Bound diffusion of ultrafine particles of FeIII hydroxide in the pores of a solvated polymeric sorbent has been discovered and investigated by Mossbauer spectroscopy. Particles with diameters of 30 A 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 A for water,D > 2 × 10−8 cm2 s−1 andr = 0.22; 0.45 A. Unlimited diffusion of particles in the solvated sorbent was not observed. No diffusion of the particles was observed in the dry sorbent.