Modeling interactions of Hg(II) and bauxitic soils.
The adsorptive interactions of Hg(II) with gibbsite-rich soils (hereafter SOIL-g) were modeled by 1-pK surface complexation theory using charge distribution multi-site ion competition model (CD MUSIC) incorporating basic Stern layer model (BSM) to account for electrostatic effects. The model calibrations were performed for the experimental data of synthetic gibbsite-Hg(II) adsorption. When [NaNO(3)] > or = 0.01M, the Hg(II) adsorption density values, of gibbsite, Gamma(Hg(II)), showed a negligible variation with ionic strength. However, Gamma(Hg(II)) values show a marked variation with the [Cl(-)]. When [Cl(-)] > or = 0.01M, the Gamma(Hg(II)) values showed a significant reduction with the pH. The Hg(II) adsorption behavior in NaNO(3) was modeled assuming homogeneous solid surface. The introduction of high affinity sites, i.e., >Al(s)OH at a low concentration (typically about 0.045 sites nm(-2)) is required to model Hg(II) adsorption in NaCl. According to IR spectroscopic data, the bauxitic soil (SOIL-g) is characterized by gibbsite and bayerite. These mineral phases were not treated discretely in modeling of Hg(II) and soil interactions. The CD MUSIC/BSM model combination can be used to model Hg(II) adsorption on bauxitic soil. The role of organic matter seems to play a role on Hg(II) binding when pH>8. The Hg(II) adsorption in the presence of excess Cl(-) ions required the selection of high affinity sites in modeling.
Weerasooriya
Rohan
R
CML, Institute of Fundamental Studies, Hantana Kandy 20000, Sri Lanka. rweerasooriya@hotmail.com
Tobschall
Heinz J
HJ
Bandara
Atula
A
D000327:Adsorption; D000537:Aluminum Oxide / Q000032:analysis*; D007700:Kinetics; D017669:Mercury Compounds / Q000737:chemistry*; D008956:Models, Chemical; D012987:Soil / Q000032:analysis* / Q000592:standards; D012989:Soil Pollutants / Q000737:chemistry*
D017669:Mercury Compounds; D012987:Soil; D012989:Soil Pollutants; D000537:Aluminum Oxide