Effects of pressure on graphene oxide nanoparticle deposition and transport in GCLs

The leakage of graphene oxide nanoparticles (GONPs) in landfills poses a great threat to the environment. A series of column tests were conducted to investigate the effects of hydrostatic pressure, input concentration and bentonite modification on the transport of GONPs in the geosynthetic clay liner (GCL). The experimental results show that pressure affected the mobility of GONPs at high input concentrations, while this effect was smaller at low input concentrations. The retention of GONPs in a GCL containing thermally modified bentonite (TMB) and sodium-modified bentonite (SMB) was greater than that in a GCL containing unmodified bentonite. The type of TMB, SMB and unmodified bentonite was granular bentonite. The sorption and deposition of GONPs in GCLs were also investigated. Pressure affected the deposition of GONPs by decreasing the permeability of the GCL and delaying the transport of GONPs but had little effect on the sorption of GONPs. The dependence of GONP retention on pressure was greater at high input concentrations than that at low input concentrations. The sorption of GONPs in TMB and SMB was much greater than that in unmodified bentonite because of the greater specific surface area and lower negative zeta potentials of TMB and SMB.