Modeling the Transport Behavior of Zinc Oxide Nanoparticles in Soil Under Various Environmental Conditions

Transport behavior of zinc oxide nanoparticles (nZnO) has been investigated widely; however, not many studies have identified the transport mechanisms through mathematical modeling by simulating both breakthrough curve (BTC) and retention profile (RP) under varying environmental conditions. Thus, this study focuses on investigating the transport behavior of nZnO in the subsurface under a wide range of environmental conditions through mathematical modeling. A mathematical model is developed to simulate nZnO transport in porous media and the values of the associated parameters are estimated by fitting the model to the experimental data under a broad range of physicochemical conditions reported in the literature. The model performance is assessed by evaluating its ability to simulate both the nZnO BTC and RP, and it demonstrates promising performance. It is found that nZnO retention in the soil is mainly governed by reversible deposition on grain surfaces and straining. Moreover, nZnO transport through coarse-grained soil at high velocity and low ionic strength (IS) in the presence of a dissolved form of natural organic matter (NOM) may lead to an increased risk of groundwater contamination. The nZnO transport behavior can be simulated better by incorporating size-dependent dispersivity in the developed model.