Temperature Effect on the Sulfur Adsorption-Diffusion Processes from Potassium Pentathionate Solutions by Polycaproamide Film

Abstract

The temperature effect on the sulfur adsorption-diffusion processes by polycaproamide film to 4 h exposed in the
acidified 0.15 mol·dm–3 water solutions of potassium pentathionate, K2S5O6, is investigated by methods of UV, IR
absorption spectroscopy and chemical analysis. The pentathionate anions S5O6
2– were found to sorb into a polymer. IR
absorption spectra were investigated in the region of the wavenumbers 200 cm–1 – 1400 cm–1. The characteristic
absorption peaks were found in the regions 240 – 245, 337 – 385, 416 – 470, 523 – 538, 580 – 611, 1020 – 1022,
1170 – 1268 cm–1 and assigned, respectively, to δ(SSS), γr(SO3), ν(S−S), δas(O−S−O), δs(O−S−O), νs(S−O) and
νas(S−O). The kinetic study of sulfur adsorption-diffusion processes showed that sorbed pentathionate ions concentration
in a polymers film sample increases with increasing temperature of the K2S5O6 solution and the duration of treatment.
Sulfur concentration in the polymer, depends on the conditions for the process of sorption and it varies from 0.94 mg·cm–3
to 7.64 mg·cm–3. The estimated apparent sulfur diffusion coefficients in polycaproamide increase with increasing
temperature of the potassium pentathionate solution. The concentration of sulfur in a polymer film is no limited by the
stage of pentathionate decomposition, since the apparent activation energy of pentathionate diffusion in
polycaproamide is four times smaller than that needed for the polythionate decomposition.