Experimental and numerical investigation of the effect of temporal variation in ionic strength on colloid retention and remobilization in saturated porous media

Krishna, Yerramilli Sai Rama and Seetha, N. and Hassanizadeh, S. Majid (2022) Experimental and numerical investigation of the effect of temporal variation in ionic strength on colloid retention and remobilization in saturated porous media. Journal of Contaminant Hydrology, 251. pp. 1-11. ISSN 0169-7722

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Abstract

Temporal variations in the chemistry of infiltrating water into the subsurface are known to cause remobilization of colloids from the grain surfaces, thereby increasing the travel distance of the colloidal contaminants. Hence, it is essential to thoroughly understand the transport, deposition, and release mechanisms of colloids in the sub-surface, through laboratory experiments and modeling. There are only a few experiments in which the chemistry of inflow water is changed rapidly during colloid transport. Also, although some models have been presented for simulating the effect of transient chemistry on the fate of colloids, there is no consensus in this regard, as the proposed models suffer from shortcomings. In this study, we systematically investigated the effect of temporal variations in ionic strength on the remobilization of deposited colloids in saturated porous media through lab-oratory column experiments and numerical modeling. Four sets of column experiments were performed, in which we injected carboxylate-modified latex colloids at a given ionic strength for a specified period. After break-through of colloids, the ionic strength of inflowing water was decreased in a stepwise manner to 0 mM (DI water). The initial ionic strength values of the four experiments were 100, 50, 25, and 10 mM. We observed partial release of deposited colloids after several steps of ionic strength decrease with significant release observed only when the ionic strength was reduced to below 10 mM. We also found that the fraction of released colloids decreased with increasing value of initial ionic strength of inflow water. We have developed a mathematical model incorporating a novel formulation for ionic strength-dependent deposition and release. The model is found to capture the colloid breakthrough curves reasonably well for all experiments with the same set of parameter values, except the one at the initial ionic strength of 25 mM.

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IITH Creators:

IITH Creators	ORCiD
Seetha, N.	UNSPECIFIED

Item Type:

Article

Additional Information:

The authors acknowledge the funding received from Science and Engineering Research Board (SERB), Government of India (sanction no. VJR/2020/000006) for carrying out this work. SMH acknowledges support form Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy -EXC 2075-390740016 and from the Stuttgart Center for Simulation Science (Sim -Tech). The authors also thank the anonymous reviewers for their valuable comments which helped to improve the manuscript.

Uncontrolled Keywords:

DETACHMENT,MECHANISMS,ADSORPTION

Subjects:

Civil Engineering

Divisions:

Department of Civil Engineering

Depositing User:

. LibTrainee 2021

Date Deposited:

22 Nov 2022 06:46

Last Modified:

22 Nov 2022 06:46