Development of a scalable model for predicting arsenic transport coupled with oxidation and adsorption reactions
journal contribution
posted on 2017-09-29, 14:11authored byTanja RaduTanja Radu, Anjani Kumar, T. Prabhakar Clement, Gautham Jeppu, Mark O. Barnett
Understanding the fundamentals of arsenic adsorption and oxidation reactions is critical for predicting its transport dynamics in groundwater systems. We completed batch experiments to study the interactions of arsenic with a common MnO 2 (s) mineral, pyrolusite. The reaction kinetics and adsorption isotherm developed from the batch experiments were integrated into a scalable reactive transport model to facilitate column-scale transport predictions. We then completed a set of column experiments to test the predictive capability of the reactive transport model. Our batch results indicated that the commonly used pseudo-first order kinetics for As(III) oxidation reaction neglects the scaling effects with respect to the MnO 2 (s) concentration. A second order kinetic equation that explicitly includes MnO 2 (s) concentration dependence is a more appropriate kinetic model to describe arsenic oxidation by MnO 2 (s) minerals. The arsenic adsorption reaction follows the Langmuir isotherm with the adsorption capacity of 0.053μmol of As(V)/g of MnO 2 (s) at the tested conditions. The knowledge gained from the batch experiments was used to develop a conceptual model for describing arsenic reactive transport at a column scale. The proposed conceptual model was integrated within a reactive transport code that accurately predicted the breakthrough profiles observed in multiple column experiments. The kinetic and adsorption process details obtained from the batch experiments were valuable data for scaling to predict the column-scale reactive transport of arsenic in MnO 2 (s)-containing sand columns.
History
School
Architecture, Building and Civil Engineering
Published in
Journal of Contaminant Hydrology
Volume
95
Issue
1-2
Pages
30 - 41
Citation
RADU, T. ... et al., 2008. Development of a scalable model for predicting arsenic transport coupled with oxidation and adsorption reactions. Journal of Contaminant Hydrology, 95 (1-2), pp.30-41.
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