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Contaminant transport in soil: A comparison of the Theory of Porous Media approach with the microfluidic visualisation

Seyedpour, S.M., Janmaleki, M., Henning, C., Sanati-Nezhad, A., Ricken, T.
The Science of the total environment 2019 v.686 pp. 1272-1281
Fourier transform infrared spectroscopy, decision making, environmental fate, fluid mechanics, groundwater flow, hydrophilicity, nanoclays, organ-on-a-chip, polydimethylsiloxane, porous media, remediation, scanning electron microscopy, soil
Visualisation of the groundwater flow and contaminant transport can play a significant role for a better understanding of contaminant fate, which helps decision-makers and contaminated site planners to choose and implement the best remediation strategies. In this paper, a microfluidic chip coated with nanoclay was developed to mimic soil behaviour. Scanning electron microscopy (SEM) images and Fourier-transform infrared spectroscopy (FTIR) analysis confirmed that all the features and surfaces are coated with nanoclay. The change of contact angle for the native polydimethylsiloxane (PDMS) from 151° ± 4° to 73° ± 6° for modified ones is indicative of a considerable shift to hydrophilic behaviour. Moreover, the transport process in the developed chip was simulated utilising the Theory of Porous Media (TPM) and computational fluid dynamic (CFD) approaches. Although the results of both numerical approaches are in good agreement with experiments, the Root Mean Square Error (RMSE) of the predicted contaminant concentration by TPM at two observation points is less than that of CFD.