Adsorption of the inhalation anaesthetic isoflurane by activated carbon fibres with reference data on non-porous carbon

Abstract

Activated carbon fibres with a range of pore sizes, prepared from pre-oxidized acrylic fibre by physical activation in carbon dioxide at different temperatures and times, were investigated as adsorbents for the inhalation anaesthetic isoflurane (2-chloro-2-(difluoromethoxy)-1,1,1-trifluoroethane). Adsorption-desorption isotherms of isoflurane were determined at 293 K and were analysed by the alpha-S method using reference adsorption data, determined also at 293 K, on non-porous carbon. One of the samples obtained showed a much higher adsorption uptake at 100 mbar than reported in previous studies on different materials, while another sample not only showed a higher adsorption uptake than reported previously, but also a higher adsorption uptake at a pressure as low as 1 mbar showing potential for the capture of isoflurane. The results indicate that isoflurane does not adsorb in fine ultramicropores, of width less than about 0.5 nm. Comparison of the pore size distributions of these materials indicated that the presence of supermicropores, as well as ultramicropores, is relevant for the adsorption of isoflurane even at trace levels. Reference adsorption data for isoflurane on non-porous carbon is also presented.