Assessment on landfill liners as the barrier against C₆₀ nanoparticles

Owing to the increasing usage of nanomaterials, it is imperative to assess their potential impacts on natural systems, and in particular, investigate if existing barriers can prevent nanomaterial emission in landfills because they will be disposed in landfills at the end of their useful lives. This study inspected the behavior of colloidal fullerene (nC₆₀) in and around landfill liner materials. Sorption isotherm experiments using either natural soil or high density polyethylene geomembrane as sorbents showed that nC₆₀ was readily removed by sorption to soil and precipitation, while there was no sorption to geomembrane. To investigate transport through soil, nC₆₀ was injected into columns of compacted soil layers with a thickness of 3.3-4.2 cm and hydraulic conductivity <1 × 10^-7 cm/s. The nanoparticles rarely passed through the layers owing to self-aggregation and/or screening by the soil layer. When they were detected in the effluent, breakthrough curves of an extraordinary shape were produced, which is presumably attributed to surface modification of collectors by deposited nC₆₀. However, simulation using the obtained mass transport parameters showed that it is unlikely that nC₆₀ from disposed C₆₀-containing products would overcome compacted clay liners; therefore, its migration to the ambient environment would be negligible.