Performance comparison survey of multi-walled and single-walled carbon nanotubes for adsorption and desorption of Mercury Vapors in the air

Sampling of toxic mercury vapors (Hg0) is necessary for determination of occupational exposure levels of workers exposed to this contaminant. Given the tendency of carbon nanotubes for mercury adsorption, carbon nanotubes can be expected to be suitable sampling media for mercury. The aim of this study was to compare the performance of multi-walled and single-walled carbon nanotubes (SWCNT, MWCNT) in absorption of mercury vapors in the air. In this experimental study, the efficiency of absorption and different variables that affected on adsorption of mercury vapor such as, adsorption efficiency, desorption mass amounts of mercury, adsorption capacity, the time and temperature of desorption, repeatability, and retention time of mercury were optimized. Statistical method, one way - anova, multiple linear regression and T - test were used for survey of results accuracy. Capacity and adsorption efficiency of adsorbents related to mass amounts of adsorbents, type of carbon nanotubes and mass amounts of mercury. In this method, working range in SWCNT and MWCNT were 0.006 – 0.7 and 0.006 – 3 g respectively. The minimum of adsorption capacity in 80 mg of SWCNT and MWCNT was 0.006 g. The optimum time and temperature desorption for amounts of mercury were 10 minute and 250 °C respectively. The retention time of mercury adsorbed (90%) on carbon nanotubes was more than 3 weeks. Carbon nanotubes have the potential to be used for adsorption/ desorption of mercury vapors in the air.