吸汞载银活性炭纤维和吸汞活性炭纤维的热脱附特性研究

Both silverloaded activated carbon fibre (silver-loaded ACF) with the silver content of 14.07% and activated carbon fibre (ACF) in form of sheet shape were tested to get their saturation adsorption capacities for mercury in a nitrogen stream. Results showed that silver-loaded ACF and ACF had a saturation adsorption capacity of 192.3mg/g and 29.4mg/g at 70℃, which was 48~192 and 7~29 fold that of common activated carbon, respectively. The thermal desorption characteristics of elemental mercury of the two sorbents were investigated by thermogravimetric analysis (TGA). Mercury desorption from silver-loaded ACF occurred in the temperature range of 100℃~650℃, and mercury desorption efficiency was 94.73% as temperature increased from 50℃ to 650℃ within 70min. Mercury desorption from ACF occurred in the temperature range of 100℃~230℃, and mercury desorption efficiency was 69.93% as temperature increased from 50℃ to 350℃ within 40min. Both silver-loaded ACF samples undergoing mercury adsorption and thermal desorption run were analyzed by scanning electron microscope (SEM). Results showed that after mercury adsorption run, the silver enriched in silver amalgam particles and intensively distributed on the junctures of ACF microcrystals. And after thermal desorption run, the enriching silver got to dispersedly distribute on the surface of ACF in form of globular particles in submicronsize or nanosize. The SEM micrographs of ACF after mercury adsorption and thermal desorption run showed that the elemental mercury by physical adsorption disappeared but mercuric oxide particles by chemical adsorption had a little increase. It suggested that elemental mercury can easily be removed by thermal treatment but mercuric oxide can't be removed. Parts of elemental mercury might transform to mercuric oxide during thermal desorption run.