title: Intra-particle migration of mercury in granular polysulfide-rubber-coated activated carbon (PSR-AC).
abstract: The depth profile of mercuric ion after the reaction with polysulfide-rubber-coated activated carbon (PSR-AC) was investigated using micro-X-ray fluorescence (μ-XRF) imaging techniques and mathematical modeling. The μ-XRF results revealed that mercury was concentrated at 0-100 μm from the exterior of the particle after 3 months of treatment with PSR-AC in 10 ppm HgCl(2) aqueous solution. The μ-X-ray absorption near edge spectroscopic (μ-XANES) analyses indicated HgS as a major mercury species, and suggested that the intra-particle mercury transport involved a chemical reaction with PSR polymer. An intra-particle mass transfer model was developed based on either a Langmuir sorption isotherm with liquid phase diffusion (Langmuir model) or a kinetic sorption with surface diffusion (kinetic sorption model). The Langmuir model predicted the general trend of mercury diffusion, although at a slower rate than observed from the μ-XRF map. A kinetic sorption model suggested faster mercury transport, which overestimated the movement of mercuric ions through an exchange reaction between the fast and slow reaction sites. Both μ-XRF and mathematical modeling results suggest mercury removal occurs not only at the outer surface of the PSR-AC particle but also at some interior regions due to a large PSR surface area within an AC particle.
authors: Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305-4020, United States. kimea@stanford.edu
authors: Eun-Ah
authors: EA
authors: Kim
authors: Yoko
authors: Y
authors: Masue-Slowey
authors: Scott
authors: S
authors: Fendorf
authors: Richard G
authors: RG
authors: Luthy
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D004058:Diffusion; D057927:Hydrophobic and Hydrophilic Interactions; D008628:Mercury / Q000032:analysis / Q000737:chemistry*; D008962:Models, Theoretical; D016062:Porosity; D012408:Rubber / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*
chemical_list: D013440:Sulfides; D002244:Carbon; D012408:Rubber; C032915:polysulfide; D008628:Mercury