Co-transport of Pb(II) and oxygen-content-controllable graphene oxide from electron-beam-irradiated graphite in saturated porous media

Highlights: • GO of different oxygen content was prepared from irradiated graphite. • Surface functional groups may hinder the transport of GO at a certain flow rate and IS. • The more oxygen content, the stronger was the ability of GO to promote Pb(II) transport. • The surface oxygen content promoted the ability of GO to re-release Pb(II). -- Abstract: It is essential to investigate the role of the surface oxygen content of graphene oxide (GO) in transport processes. In this study, GO was prepared using flake graphite with different radiation doses. The effects of the flow rate and ionic strength (IS) on the migration and co-transport of GO and Pb(II) ions were investigated via laboratory packed-column experiments. The experimental results showed that the mobility of GO in saturated porous media decreased with increasing flow rate. Further, the mobility of GO with a radiation dose of 18 kGy was lower than that of GOs with other radiation doses for an IS below 0.01 M. Regarding the co-transport of irradiated GO and Pb(II) in porous media, the greater the radiation dose, the stronger was the ability of GO to promote Pb(II) transport. The surface oxygen content promoted the ability of GO to remove Pb(II). However, radiation doses exceeding a certain range inhibited the release of Pb(II). The transport of GO in saturated porous media was successfully simulated with the advection–dispersion–reaction (ADR) equation. This study is expected to provide a new perspective on the potential risks of GO due to surface changes during its transport in the environment.