Sustainable Recovery of Gaseous Mercury by Adsorption and Electrothermal Desorption Using Activated Carbon Fiber Cloth

摘要

The present work aims to develop a novel and sustainable approach to adsorb and recover low-concentration Hg~0 in the off-gas downstream a distillation/condensation system in the recycling processes for waste Hg-containing devices.Hg~0 adsorption and regeneration efficiencies of raw and HNO_3-treated activated carbon fiber cloth (ACFC) were examined.The adsorption experiments were conducted with an initial Hg~0 concentration of 260-300 μg/m~3 at room temperature.The regeneration of ACFC was done by an electrothermal swing process with 20,40,and 60 W direct currents.The experimental results showed that the Hg~0 adsorption efficiency of raw ACFC increased to approximately 90% after the 60 W electrothermal regeneration.After HNO_3 treatment,the content of oxygen functional groups on HNO_3-treated ACFC increased,which enhanced the Hg~0 adsorption performance and resulted in over 90% adsorption efficiency for the samples before and after electrothermal regeneration.Importantly,both raw and HNO_3-treated ACFCs retained the high adsorption efficiency after nine cycles of adsorption/regeneration,indicating that both raw and HNO_3-treated ACFCs were effective and renewable adsorbents for low-concentration Hg~0 adsorption and recovery.A Hg adsorption/regeneration mechanism was proposed to explain the increasing adsorption efficiency after electrothermal regeneration and the great adsorption efficiency of HNO_3-treated ACFC.