Illite spatial distribution patterns dictate Cr(VI) sorption macrocapacity and macrokinetics

Li Wang, Li Li

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

This work examines the largely unexplored role of illite spatial distribution patterns in dictating the sorption of Cr(VI), a ubiquitously occurring contaminant. Flow-through experiments were carried out at 0.6, 3.0, and 15.0 m/day using columns packed with the same illite and quartz mass however with different spatial patterns and permeability contrasts. Column-scale sorption macrocapacity and macrorates were found to decrease with transport connectivity, a quantitative measure of heterogeneity characteristics. At 0.6 and 3.0 m/day, well-connected low permeability illite zones oriented in the flow-parallel direction lead to diffusion-controlled mass transport limitation for accessing sorption sites. This results in up to 1.4 order of magnitude lower macrocapacity and macrorates compared to those in minimally connected columns with well-mixed illite and quartz. At 15.0 m/day, effects of spatial heterogeneities are less significant (up to a factor of 2.8) owing to the close to chemical kinetics-controlled condition. Although the column-scale macrocapacity can reach full sorption capacity under low flow conditions, the macrorates are 10-1 to 10-3 of the microrates measured in well-mixed reactors. Insights gained here bridge gaps between laboratory observations and field applications and advance predictive understanding of reactive transport processes in the naturally heterogeneous subsurface.

Original languageEnglish (US)
Pages (from-to)1374-1383
Number of pages10
JournalEnvironmental Science and Technology
Volume49
Issue number3
DOIs
StatePublished - Feb 3 2015

Fingerprint

illite
Spatial distribution
Sorption
sorption
spatial distribution
Quartz
permeability
quartz
Parallel flow
reactive transport
mass transport
transport process
Reaction kinetics
low flow
connectivity
Mass transfer
Impurities
kinetics
chromium hexavalent ion
pollutant

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry

Cite this

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abstract = "This work examines the largely unexplored role of illite spatial distribution patterns in dictating the sorption of Cr(VI), a ubiquitously occurring contaminant. Flow-through experiments were carried out at 0.6, 3.0, and 15.0 m/day using columns packed with the same illite and quartz mass however with different spatial patterns and permeability contrasts. Column-scale sorption macrocapacity and macrorates were found to decrease with transport connectivity, a quantitative measure of heterogeneity characteristics. At 0.6 and 3.0 m/day, well-connected low permeability illite zones oriented in the flow-parallel direction lead to diffusion-controlled mass transport limitation for accessing sorption sites. This results in up to 1.4 order of magnitude lower macrocapacity and macrorates compared to those in minimally connected columns with well-mixed illite and quartz. At 15.0 m/day, effects of spatial heterogeneities are less significant (up to a factor of 2.8) owing to the close to chemical kinetics-controlled condition. Although the column-scale macrocapacity can reach full sorption capacity under low flow conditions, the macrorates are 10-1 to 10-3 of the microrates measured in well-mixed reactors. Insights gained here bridge gaps between laboratory observations and field applications and advance predictive understanding of reactive transport processes in the naturally heterogeneous subsurface.",
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Illite spatial distribution patterns dictate Cr(VI) sorption macrocapacity and macrokinetics. / Wang, Li; Li, Li.

In: Environmental Science and Technology, Vol. 49, No. 3, 03.02.2015, p. 1374-1383.

Research output: Contribution to journalArticle

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