Transport of Oxygen-Doped Graphitic Carbon Nitride in Saturated Sand: Effects of Concentration, Grain Size, and Ionic Strength

Abstract

In this study, the characteristics and transport of oxygen-doped graphitic carbon nitride (OgCN) were investigated in comparison with multi-walled carbon nanotube (MWCNT), and the transport of OgCN was evaluated under various conditions. OgCN was superior to MWCNT in transport within a quartz sand layer with less attachment and more detachment than MWCNT, which is attributable to more diverse and abundant functional groups, charges, defects, and amorphous graphitic structures. OgCN transport was well described by a one-dimensional advection–dispersion–retention model. The coefficients of retention (Smax), attachment (ka), and detachment (kd) calculated by the model were not always well-correlated with OgCN concentration and the grain size of the medium, suggesting that the OgCN transport was affected by various factors such as attachment, detachment, and pore size. However, it was clearly and significantly inhibited by ionic strength, via improved aggregation of OgCN. It is believed that the results of this study contribute to establish proper sub-surface injection strategies of carbonaceous materials for in situ chemical oxidation.