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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 (?-XRF) imaging techniques and mathematical modeling. The ?-XRF results revealed that mercury was concentrated at 0-100 ?m from the exterior of the particle after 3 months of treatment with PSR-AC in 10 ppm HgCl(2) aqueous solution. The ?-X-ray absorption near edge spectroscopic (?-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 ?-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 ?-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.

SUBMITTER: Kim EA

PROVIDER: S-EPMC3265622 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature

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Intra-particle migration of mercury in granular polysulfide-rubber-coated activated carbon (PSR-AC).

Kim Eun-Ah EA Masue-Slowey Yoko Y Fendorf Scott S Luthy Richard G RG

Chemosphere 20111130 6

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, a ...[more]

PMID: 22133913

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Project description:Microporous annealed particle (MAP) hydrogels are porous 3D scaffolds generated by interlinking randomly packed microgels (µgels). Particle fraction, hydrogel stiffness, microparticle shape, and crosslinking chemistry are paramount to the microstructure that microgels make within MAP scaffolds. Of these parameters, control over the particle fraction in MAP scaffolds varies greatly by user and drying technique, leading to inconsistent microarchitectures. These inconsistencies have biological ramifications, as the particle fraction of MAP scaffolds determines the void space within the material which strongly impacts cell growth. Here, we describe a method of freeze-drying microgels that leads to consistent and user-defined particle fractions by weighing the dried microgel powder and reconstituting at known volumes. Though freeze-drying hydrogels typically leads to ice crystal and cryogel formation, we report on mediums that result in freeze-dried microgels that retain their original properties when rehydrated. By rehydrating lyophilized microgels to form MAP scaffolds, we demonstrate that particle fraction controls the bulk scaffold stiffness, but not local microgel stiffness. Further, the particle fraction in MAP scaffolds directly affects cell growth and macromolecular diffusion. Using controlled particle fractions in MAP scaffolds, we can now reproducibly assess mechanical properties, diffusion of macromolecules, and cell responses within user-defined microarchitectures. STATEMENT OF SIGNIFICANCE: The porosity of biomaterials is one key characteristic that influences cell infiltration and growth. Granular hydrogels are a class of biomaterials that are comprised of small, building block components that boast a porous architecture in the void space between the particles. Controlling the composition of these granular materials is key to guiding cell responses. In this work, we demonstrate methods for controlling the fraction of the material containing hydrogel versus void space. As a result, we can now reproducibly study the effect of particle fraction on cell responses, mechanical properties, and mass transport in granular hydrogels.

Dataset Information

Intra-particle migration of mercury in granular polysulfide-rubber-coated activated carbon (PSR-AC).

Publications

Intra-particle migration of mercury in granular polysulfide-rubber-coated activated carbon (PSR-AC).

Similar Datasets

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