Enhancement of elemental mercury adsorption by silver supported material
Rattabal Khunphonoi , Pummarin Khamdahsag , Siriluk Chiarakorn , Nurak Grisdanurak
,
Adjana Paerungruang
,
Somrudee Predapitakkun
DOI:10.1016/j.jes.2015.01.008
Received August 21, 2014,Revised January 19, 2015, Accepted January 20, 2015, Available online April 22, 2015
Volume 27,2015,Pages 207-216
Mercury, generally found in natural gas, is extremely hazardous. Although average mercury levels are relatively low, they are further reduced to comply with future mercury regulations, which are stringent in order to avoid releasing to the environment. Herein, vapor mercury adsorption was therefore investigated using two kinds of supports, granular activated carbon (GAC) and titanium dioxide (TiO2). Both supports were impregnated by silver (5 and 15 wt.%), before testing against a commercial adsorbent (sulfur-impregnated activated carbon, SAC). The adsorption isotherm, kinetics, and its thermodynamics of mercury adsorption were reported. The results revealed that Langmuir isotherm provided a better fit to the experimental data. Pseudo second-order was applicable to describe adsorption kinetics. The higher uniform Ag dispersion was a key factor for the higher mercury uptake. TiO2 supported silver adsorbent showed higher mercury adsorption than the commercial one by approximately 2 times. Chemisorption of mercury onto silver active sites was confirmed by an amalgam formation found in the spent adsorbents.
